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Montreal, Canada

The Université de Montréal is a public research university in Montreal, Quebec, Canada. The francophone institution comprises thirteen faculties, more than sixty departments and two affiliated schools: the École Polytechnique and HEC Montréal . It offers more than 650 undergraduate programmes and graduate programmes, including 71 doctoral programmes. The Times Higher Education World University Rankings of 2012-2013 ranks the Université de Montréal at 84th place globally.The university has Quebec's largest sponsored research income and the third largest in Canada, allocating close to $524.1 million to research conducted in more than 150 research centres as of 2011. It is also part of the U15 universities. More than 55,000 students are enrolled in undergraduate and graduate programs, making it the second-largest university in Canada in terms of student enrolment. Wikipedia.

Carnis L.,French Institute of Science and Technology for Transport | Blais E.,University of Montreal
Accident Analysis and Prevention | Year: 2013

This article presents the results of an evaluation of the speed camera program implemented in France in November 2003. The effects of this program on traffic casualties were estimated using interrupted time-series analyses. Various parametizations were attempted in order to capture changes in the constant and the slope of our traffic injury series. Results of the study reveal significant decreases in both fatal and non-fatal traffic injuries on the whole road network following deployment of the speed camera program. The fatality rate per 100,000 vehicles fell by 21% whereas the decrease in non-fatal traffic injuries displayed a decay function: a 26.2% reduction was recorded in the first month but dropped to 0.8% for the last observation of the series. © 2012 Elsevier Ltd.

Expatriate health care professionals frequently participate in international responses to natural disasters and humanitarian emergencies. This field of practice presents important clinical, logistical and ethical challenges for clinicians. This paper considers the ethics of health care practice in humanitarian contexts. It examines features that contribute to forming the moral landscape of humanitarian work, and discusses normative guidelines and approaches that are relevant for this work. These tools and frameworks provide important ethics resources for humanitarian settings. Finally, it elaborates a set of questions that can aid health care professionals as they analyse ethical issues that they experience in the field. The proposed process can assist clinicians as they seek to establish their moral bearings in situations of ethical complexity and uncertainty. Identifying and developing ethics resources and vocabulary for clinical practice in humanitarian work will help health care professionals provide ethically sound care to patients and communities. © Overseas Development Institute, 2011.

Addressing adolescent sexual and reproductive health issues are central to efforts for reducing childhood and maternal mortality embedded in MDG4 and MDG5. This paper reviews these issues in Africa and uses statistical methods for measuring changes to analyze recent and comparable time series data from 51 African countries. The contribution of adolescent fertility to total fertility and mortality remains quite high. Delayed marriage is occurring concomitantly with postponement of sexual debut among unmarried adolescents. Six African countries are likely to achieve the MGD4 and five are likely to reach the target for the MDG5; the majority of sub-Saharan African countries will fall short of achieving these goals, not even by 2100 for many at current rates of change in progress indicators. Implementing ground-breaking nationally owned mortality-reduction schemes covering preconceptional and interconceptional periods and well-functioning comprehensive health-care system secured by sustained commitments and financial investments in health and social services are urgently needed, in order to repeal trends of further undoing successes achieved so far or slowing recent progress, thus hastening the pace of child and maternal mortality decline.

Context: The contribution of anaesthesia itself to post-operative cognitive dysfunction (POCD) or the potential protective effect of one specific type of anaesthesia on the occurrence of POCD is unclear. Aims: This is a meta-analysis evaluating the effects of the anaesthetic technique (regional vs. general anaesthesia) on POCD of patients undergoing non-cardiac surgery. Settings and Design: Meta-analysis performed in a University affiliated hospital. Methods: A search for randomized controlled trials (RCT) comparing regional anaesthesia to general anaesthesia for surgery was done in PUBMED, MEDLINE, EMBASE, EBM Reviews-Cochrane Central Register of Controlled Trials, PsychINFO and Current Contents/all editions in 2009. Statistical Analysis: Data were analyzed with comprehensive Meta-analysis Version 2.2.044. Results: Twenty-six RCTs including 2365 patients: 1169 for regional anaesthesia and 1196 for general anaesthesia were retained. The standardized difference in means for the tests included in the 26 RCTs was -0.08 (95% confidence interval: -0.17-0.01; P value 0.094; I-squared = 0.00%). The assessor was blinded to the anaesthetic technique for 12 of the RCTs including only 798 patients: 393 for regional anaesthesia and 405 for general anaesthesia. The standardized difference in means for these 12 studies is 0.05 (-0.10-0.20; P=0.51; I-squared = 0.00%). Conclusions: The present meta-analysis does not support the concerns that a single exposure to general anaesthesia in an adult would significantly contribute to permanent POCD after non-cardiac surgery.

Geitmann A.,University of Montreal
Current Opinion in Plant Biology | Year: 2010

Plant cell growth is a fundamental process during plant development whose spatial and temporal dynamics are controlled by the cell wall. Modeling mechanical aspects of cell growth therefore requires the integration of structural cell wall details with quantitative biophysical parameters. Recent advances in microscopic techniques and mechanical modeling have made significant contributions to the field of cell wall biomechanics. Live observation of cellulose microfibrils at high z-resolution now enables determining the dynamic orientation of these polymers in the different wall layers of growing cells. Mechanical modeling approaches have been developed to operate at the scale of individual molecules and will thus be able to exploit the availability of the high-resolution structural data. The combination of these techniques has the potential to make a significant and quantitative contribution to our understanding of plant growth and development. © 2010 Elsevier Ltd.

Mailhot G.,University of Montreal
Nutrition Reviews | Year: 2012

Despite the inclusion of extra vitamin D in their regimen of fat-soluble vitamin supplementation, cystic fibrosis patients remain chronically depleted of vitamin D. The persistence of suboptimal vitamin D status is often blamed on the maldigestion and malabsorption of fat. However, the mitigated success of recent clinical trials with high-dose vitamin D supplementation suggests that vitamin D bioavailability might be impaired in these patients. Given the growing understanding of the importance of this vitamin in the regulation of multiple biological functions beyond skeletal health, the present review analyzes the current literature by addressing each step of vitamin D metabolism and action in the context of this life-limiting pathology. In addition, it highlights the importance of vitamin D in relation to organs and or conditions affected by cystic fibrosis. © 2012 International Life Sciences Institute.

Yang H.,McGill University | Metera K.L.,University of Montreal | Sleiman H.F.,McGill University
Coordination Chemistry Reviews | Year: 2010

DNA has recently emerged as a useful building block for higher order nanostructures, such as extended two-dimensional surfaces and discrete two- and three-dimensional structures. Transition metal complexes can introduce functionality to these otherwise passive nanostructures. This review examines the synthetic strategies used to introduce metals in a site-specific manner to DNA: either by attaching preformed metal complexes to DNA, or by metal coordination to unmodified or modified DNA. The applications of metal-DNA complexes in building higher order nanostructures and the utility of attaching luminescent or electrochemical labels are discussed. © 2010.

Fakhoury M.,University of Montreal
Journal of Neurology | Year: 2016

Neurodegeneration is a pathological condition that predominantly affects neurons. It represents a large spectrum of disorders with heterogeneous symptoms and distinct clinical features. In addition to the devastating effects it can have on the affected individual, it constitutes a heavy burden to the society in terms of health care costs. Although the exact cause of neurodegeneration is not known, there are plenty of evidences supporting the notion that the immune system is strongly associated with various forms of neurodegenerative diseases. Given the numerous functions of immune cells, a change in their expression can either be beneficial or deleterious to the host. A better understanding of the molecular and cellular processes in neurodegeneration is therefore needed. This could facilitate the development of new therapeutic targets and provide effective means to dampen the progression of neurodegenerative disorders. The overarching aim of this paper is to provide an overview of the roles that the innate and adaptive immune systems play in the central nervous system, and to discuss their beneficial or detrimental effects during neurodegeneration. This paper also critically examines the contribution of immune and inflammatory-mediated responses in the development of neurodegenerative diseases including Alzheimer’s disease (AD), Parkinson’s disease (PD), multiple sclerosis (MS), and amyloid lateral sclerosis by illustrating key findings from animal and human studies. © 2016 Springer-Verlag Berlin Heidelberg

Spano F.C.,Temple University | Silva C.,University of Montreal | Silva C.,Imperial College London
Annual Review of Physical Chemistry | Year: 2014

Aggregates of conjugated polymers exhibit two classes of fundamental electronic interactions: those occurring within a given chain and those occurring between chains. The impact of such excitonic interactions on the photophysics of polymer films can be understood using concepts of J- and H-aggregation originally developed by Kasha and coworkers to treat aggregates of small molecules. In polymer assemblies, intrachain through-bond interactions lead to J-aggregate behavior, whereas interchain Coulombic interactions lead to H-aggregate behavior. The photophysics of common emissive conjugated polymer films are determined by a competition between intrachain, J-favoring interactions and interchain, H-favoring interactions. We review formalisms describing absorption and photoluminescence lineshapes, based on intra- and intermolecular excitonic coupling, electron-vibrational coupling, and correlated energetic disorder. Examples include regioregular polythiophenes, pheneylene-vinylenes, and polydiacetylene. Copyright © 2014 by Annual Reviews.

Mignotte M.,University of Montreal
Journal of Electronic Imaging | Year: 2010

We propose an efficient regularized restoration model associating a spatial and a frequential regularizer in order to better model the intrinsic properties of the original image to be recovered and to obtain a better restoration result. An adaptive and rescaling scheme is also proposed to balance the influence of these two different regularization constraints, preventing an overwhelming importance for one of them from prevailing over the other, enabling them to be efficiently fused during the iterative deconvolution process. This hybrid regularization approach, mixing these two constraints and, more precisely, favoring a solution image that is both efficiently denoised [due to the denoising ability of a thresholding procedure in the discrete cosine transform (DCT) domain] and edge-preserved [due to the generalized Gaussian Markov random field (GGMRF) constraint]; yields significant improvements in terms of image quality and higher signal-to-noise ratio improvement results compared to a single GGMRF or DCT prior model and leads to competitive restoration results in benchmark tests, for various levels of blur, blurred signal to noise ratio (BSNR), and noise degradations. © 2010 SPIE and IS&T.

Marigold D.S.,Simon Fraser University | Drew T.,University of Montreal
Journal of Neurophysiology | Year: 2011

In the present study, we determined whether cells in the posterior parietal cortex (PPC) may contribute to the planning of voluntary gait modifications in the absence of visual input. In two cats we recorded the responses of 41 neurons in layer V of the PPC that discharged in advance of the gait modification to a 900-ms interruption of visual information (visual occlusion). The cats continued to walk without interruption during the occlusion, which produced only minimal changes in step cycle duration and paw placement. Visual occlusion applied during the period of cell discharge was without significant effect on discharge frequency in 57% of cells. In the other cells, the visual occlusion produced either significant decreases (18%) or increases (21%) of discharge activity (in 1 cell there was both an increase and a decrease). The mean latency of the changes was 356 ms for decreases and 252 ms for increases. In most neurons, discharge frequency, when modified, returned to the same levels as during unoccluded locomotion when vision was restored. In some cells, there were significant changes in discharge activity after the restoration of vision; these were associated with corrections of gait. These results suggest that the PPC is more involved in the visuomotor transformations necessary to plan gait modifications than in continual sensory processing of visual information. We further propose that cells in the PPC contribute both to the planning of gait modifications on the basis of only intermittent visual sampling and to visually guided online corrections of gait. © 2011 the American Physiological Society.

Awissi D.-K.,HOpital Maisonneuve Rosemont | Lebrun G.,HOpital Maisonneuve Rosemont | Fagnan M.,HOpital Maisonneuve Rosemont | Skrobik Y.,University of Montreal
Critical Care Medicine | Year: 2013

Objectives: The neurophysiology, risk factors, and screening tools associated with alcohol withdrawal syndrome in the ICU are reviewed. Alcohol withdrawal syndrome assessment and its treatment options are discussed. Description of nicotine withdrawal and related publications specific to the critically ill are also reviewed. A brief comment as to sedative and opiate withdrawal follows. Data and Summary: The role of currently published alcohol withdrawal syndrome pharmacologic strategies (benzodiazepines, ethanol, clomethiazole, antipsychotics, barbiturates, propofol, and dexmedetomidine) is detailed. Studies on nicotine withdrawal management in the ICU focus mainly on the safety (mortality) of nicotine replacement therapy. Study characteristics and methodological limitations are presented. Conclusion: We recommend a pharmacologic regimen titrated to withdrawal symptoms in ICU patients with alcohol withdrawal syndrome. Benzodiazepines are a reasonable option; phenobarbital appears to confer some advantages in combination with benzodiazepines. Propofol and dexmedetomidine have not been rigorously tested in comparative studies of drug withdrawal treatment; their use as additional or alternative strategies for managing withdrawal syndromes in ICU patients should therefore be individualized to each patient. Insufficient data preclude recommendations as to nicotine replacement therapy and management of iatrogenic drug withdrawal in ICU patients. © 2013 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins.

Lariviere V.,University of Montreal | Lariviere V.,University of Quebec at Montreal
Scientometrics | Year: 2012

Using the participation in peer reviewed publications of all doctoral students in Quebec over the 2000-2007 period, this paper provides the first large scale analysis of their research effort. It shows that PhD students contribute to about a third of the publication output of the province, with doctoral students in the natural and medical sciences being present in a higher proportion of papers published than their colleagues of the social sciences and humanities. Collaboration is an important component of this socialization: disciplines in which student collaboration is higher are also those in which doctoral students are the most involved in peer-reviewed publications. In terms of scientific impact, papers co-signed by doctorate students obtain significantly lower citation rates than other Quebec papers, except in natural sciences and engineering. Finally, this paper shows that involving doctoral students in publications is positively linked with degree completion and ulterior career in research. © 2011 Akadémiai Kiadó, Budapest, Hungary.

Poitout V.,Montreal Diabetes Research Center | Poitout V.,University of Montreal
Diabetologia | Year: 2013

The incretin hormones glucagon-like peptide-1 and glucose-dependent insulinotropic peptide are secreted by enteroendocrine cells and augment glucose-induced insulin secretion in response to food ingestion in a glucose-dependent manner. This mechanism forms the basis for incretin-based therapies in type 2 diabetes. However, the insulinotropic effect of incretins is diminished in type 2 diabetic patients, due in part to reduced expression of incretin receptors as a consequence of glucotoxicity. In this issue of Diabetologia, Kang et al (DOI: 10.1007/s00125-012-2776-x) provide evidence that in addition to glucotoxicity, lipotoxicity also affects incretin receptor expression and signalling in insulin-secreting cells and isolated islets. In animal models of diabetes, the authors show that co-administration of a lipid-lowering drug with a dipeptidyl peptidase-4 inhibitor or a glucagon-like peptide-1 agonist improved glucose tolerance and beta cell mass. These novel findings provide convincing support for the notion that restoring normal circulating lipid levels in type 2 diabetes might help improve the efficacy of incretin-based therapies. © 2012 Springer-Verlag Berlin Heidelberg.

Woszczyk W.,University of Montreal
Archives of Acoustics | Year: 2011

Active acoustics offers potential benefits in music halls having acoustical shortcomings and is a relatively inexpensive alternative to physical modifications of the enclosures. One critical benefit of active architecture is the controlled variability of acoustics. Although many improvements have been made over the last 60 years in the quality and usability of active acoustics, some problems still persist and the acceptance of this technology is advancing cautiously. McGill's Virtual Acoustic Technology (VAT) offers new solutions in the key areas of performance by focusing on the electroacoustic coupling between the existing room acoustics and the simulation acoustics. All control parameters of the active acoustics are implemented in the Space Builder engine by employing multichannel parallel mixing, routing, and processing. The virtual acoustic response is created using low-latency convolution and a three-way temporal segmentation of the measured impulse responses. This method facilitates a sooner release of the virtual room response and its radiation into the surrounding space. Field tests are currently underway at McGill University involving performing musicians and the audience in order to fully assess and quantify the benefits of this new approach in active acoustics.

Pearson J.M.,University of Montreal | Goriely S.,Free University of Colombia | Chamel N.,Free University of Colombia
Physical Review C - Nuclear Physics | Year: 2011

We have calculated the zero-temperature properties of the outer crust of neutron stars for four nuclear-mass models based on the Hartree-Fock-Bogoliubov method: the three most recent Skyrme-force models (HFB-19, HFB-20, and HFB-21) and the Gogny-force model D1M. While the equation of state is substantially the same for the four models, the nuclidic composition varies considerably from one model to another. We solve the Tolman-Oppenheimer-Volkoff equations by integrating inward from the surface and thereby determine the abundance of each nuclide in the outer crust of a typical neutron star of mass 1.5MTM and radius 13 km. Although the total mass of the outer crust is slightly model dependent, its thickness is essentially the same for all four models. © 2011 American Physical Society.

Ling H.,Clinical Research Institute of Montreal | Jolicoeur P.,Clinical Research Institute of Montreal | Jolicoeur P.,McGill University | Jolicoeur P.,University of Montreal
Oncogene | Year: 2013

In a previous work, we reported that young transgenic (Tg) mice expressing the intracellular domain of Notch1 (N1 IC) showed expansion of lin - CD24 + CD29 high mammary cells enriched for stem cells and later developed mammary tumors. Mammary tumor formation was abolished or greatly reduced in cyclin D1 -/- or cyclin D1 +/- N1 IC Tg mice, respectively. Here, we studied the epithelial cell subsets present in N1 IC -induced tumors. CD24 - CD29 int and CD24 + CD29 high cells were found to be present at low numbers in tumors. The latter had the same properties as those expanded in young Tg females, and neither cell population showed tumor-initiating potential nor were they required for maintenance of tumors after transplantation. CD24 int CD29 int cells were identified as tumor-initiating and mammosphere-forming cells and represent a large percentage tumor cells in this model. Their number was significantly lower in tumors from cyclin D1 +/- N1 IC Tg mice. Using cyclin D1 shRNA knockdown, we also show that N1 IC -induced tumor cells remain addicted to cyclin D1 for growth and survival. Interestingly, at lower levels of cyclin D1 or after transplantation in the presence of normal mammary cells, these N1 IC -expressing tumor cells reverted to a state of low malignancy and differentiate into duct-like structures. They seem to adopt the fate of bi-potential stem/progenitor cells similar to that of the expanded CD24+ CD29 high stem/progenitor cells from which they are likely to be derived. Our data indicate that decreasing cyclin D1 levels would be an efficient treatment for tumors induced by N1 signaling. © 2013 Macmillan Publishers Limited All rights reserved.

Jacquemet V.,University of Montreal
IEEE Transactions on Biomedical Engineering | Year: 2010

Microscale electrical propagation in the heart can be modeled by a reactiondiffusion system, describing cell and tissue electrophysiology. Macroscale features of wavefront propagation can be reproduced by an eikonal model, a reduced formulation involving only wavefront shape. In this paper, these two approaches are combined to incorporate global information about reentrant pathways into a reactiondiffusion model. The eikonal-diffusion formulation is generalized to handle reentrant activation patterns and wavefront collisions. Boundary conditions are used to specify pathways of reentry. Finite-element-based numerical methods are presented to solve this nonlinear equation on a coarse triangular mesh. The macroscale eikonal model serves to construct an initial condition for the microscale reactiondiffusion model. Electrical propagation simulated from this initial condition is then compared to the isochrones predicted by the eikonal model. Results in 2-D and thin 3-D test-case geometries demonstrate the ability of this technique to initiate anatomical and functional reentries along prescribed pathways, thus facilitating the development of dedicated models aimed at better understanding clinical case reports. © 2006 IEEE.

To investigate the feasibility, accuracy, and effect on conversion rates of intracavitary video-assisted thoracoscopic surgery ultrasonography (VATS-US) for localization of difficult to visualize pulmonary nodules. The study consisted of a prospective cohort of VATS-US for localization of intraparenchymal peripheral pulmonary nodules. Patients with pulmonary nodules not touching the visceral pleura on the computed tomography scan, who were scheduled for VATS wedge resection, were prospectively enrolled. The lobe of interest was examined: visually, using finger palpation when possible, and using the instrument sliding method. The nodule was then sought using a sterile ultrasound transducer. The primary outcome measure was the prevention of conversion to thoracotomy or lobectomy secondary to positive VATS-US findings in patients with nodules that were not identifiable using standard VATS techniques. Four different surgeons performed 45 individual VATS-US procedures during a 13-month period. Intracavitary VATS-US was able to detect 43 of 46 nodules. The sensitivity of VATS-US was 93%, and the positive predictive value was 100%. The lung nodules were visualized by thoracoscopic lung examination in 12 cases (27%), palpable by finger in 18 cases (40%), and palpable using the instrument sliding technique in 17 cases (38%). In 20 cases, lung nodules were not identifiable using any of the traditional techniques and were identified only with VATS-US. VATS-US, therefore, prevented conversion to thoracotomy or lobectomy without tissue diagnosis in 43% (20/46) of cases. Intracavitary VATS-US is a real-time, feasible, reliable, and effective method of localization of intraparenchymal pulmonary nodules during selected VATS wedge resection procedures and can decrease the conversion rates to thoracotomy or lobectomy. Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Cote-Boucher K.,University of Montreal
British Journal of Criminology | Year: 2016

This article challenges the assumption that border officers enjoy a high level of discretion. By studying customs, it provides insight into how the policing of goods and transport workers is less concerned with 'risky' individuals than it is with promoting international trade flows. In this context, border officer discretion may be seen as a hindrance that must be channeled or curtailed. Interviews with Canadian customs officers demonstrate that technologies facilitate the redistribution of compliance and risk management responsibilities among border policing actors. Such alterations in customs operations have reconfigured discretion in paradoxical ways, both extending and reducing officers' hold on decision-making. This article considers the effects of these changes on officers' use, experience and perception of discretion as well as on their occupational identity. © 2015 The Author 2015. Published by Oxford University Press on behalf of the Centre for Crime and Justice Studies (ISTD). All rights reserved.

Jeebhay M.F.,University of Cape Town | Cartier A.,University of Montreal
Current Opinion in Allergy and Clinical Immunology | Year: 2010

PURPOSE OF REVIEW: This review focuses on seafood workers engaged in harvesting, processing and food preparation. These groups are increasingly at risk of developing occupational allergy and respiratory disease as a result of seafood handling and processing activities. This review provides an update of a previous review conducted a decade ago. RECENT FINDINGS: Exposure characterization studies have demonstrated that aerosolization of seafood (muscle, visceral organs, skin/mucin) during canning and fishmeal operations result in highly variable levels of airborne particulate (0.001-11.293 mg/m) and allergens (0.001-75.748 ug/m). Occupational asthma is more commonly associated with shellfish (4-36%) than with bony fish (2-8%). Other seafood-associated biological (Anisakis) and chemical agents (protease enzymes, toxins and preservatives) have also been implicated. Atopy, smoking and level of exposure to allergens are significant risk factors for sensitization and the development of occupational asthma. Molecular studies of the allergens suggest that aside from tropomyosin and parvalbumin, other as yet uncharacterized allergens are important. SUMMARY: Future research needs to focus on detailed characterization of allergens in order to standardize exposure assessment techniques, which are key to assessing the impact of interventions. The clinical relevance of agents such as serine proteases and endotoxins in causing asthma through nonallergic mechanisms needs further epidemiological investigation. © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins.

Battinelli P.,National institute for astrophysics | Demers S.,University of Montreal
Astronomy and Astrophysics | Year: 2012

Context. Carbon stars are among the brightest intermediate-age stars. Over one hundred have been identified in the Galactic halo. Since the halo consists essentially in an old stellar population, we believe that these C stars are trespassers and belong to streams left over by disrupted dwarf spheroidal galaxies. Aims. By performing photometric monitoring we intend to detect long-period variables among halo carbon stars. We should be in position to identify Mira, semi-regular, and irregular variables and determine their period and age group. Methods. We obtained, over several semesters, K, J, and I images centered on the C stars in order to determine their variation and periodicity. Results. We establish the period of 14 program stars and discover 13 Miras among them. Most of them belong to the 1-3 Gyr age group. Conclusions. The period distribution of the halo Miras closely matches that of the Miras of Fornax. The lack of old Miras suggests that the majority of the halo Miras likely do not originate from the Sagittarius dwarf spheroidal galaxy, which is believed to be older than 5 Gyr. © 2012 ESO.

Bengio Y.,University of Montreal
Journal of Machine Learning Research | Year: 2011

Larochelle and Murray have introduced a new probailistic model, Neural Autoregressive Distribution Estimator (NADE), which is inspired by the Restricted Boltzmann Machine (RBM). The model is is a fully visible directed graphical model without any latent variable and with a left-to-right connectivity, in which each variable gets to be predicted by the previous ones in some order. NADE is compared with several other models for which the likelihood can be computed tractably, including small RBMs, FVSBNs, mixtures of multivariate Bernoulli's, the RBM multinomial, and the RBForest. The results show that the improvements in terms of log-likelihood are not just statistically significant, they are plainly large. It was found that NADE yields similar likelihoods, suggesting that tractability was achieved at almost no cost in generalization performance.

Cadotte M.,University of Toronto | Albert C.H.,CNRS Alpine Ecology Laboratory | Albert C.H.,McGill University | Walker S.C.,University of Montreal
Ecology Letters | Year: 2013

Species enter and persist in local communities because of their ecological fit to local conditions, and recently, ecologists have moved from measuring diversity as species richness and evenness, to using measures that reflect species ecological differences. There are two principal approaches for quantifying species ecological differences: functional (trait-based) and phylogenetic pairwise distances between species. Both approaches have produced new ecological insights, yet at the same time methodological issues and assumptions limit them. Traits and phylogeny may provide different, and perhaps complementary, information about species' differences. To adequately test assembly hypotheses, a framework integrating the information provided by traits and phylogenies is required. We propose an intuitive measure for combining functional and phylogenetic pairwise distances, which provides a useful way to assess how functional and phylogenetic distances contribute to understanding patterns of community assembly. Here, we show that both traits and phylogeny inform community assembly patterns in alpine plant communities across an elevation gradient, because they represent complementary information. Differences in historical selection pressures have produced variation in the strength of the trait-phylogeny correlation, and as such, integrating traits and phylogeny can enhance the ability to detect assembly patterns across habitats or environmental gradients. © 2013 John Wiley & Sons Ltd/CNRS.

Chapais B.,University of Montreal
Evolutionary Anthropology | Year: 2013

Human social evolution has most often been treated in a piecemeal fashion, with studies focusing on the evolution of specific components of human society such as pair-bonding, cooperative hunting, male provisioning, grandmothering, cooperative breeding, food sharing, male competition, male violence, sexual coercion, territoriality, and between-group conflicts. Evolutionary models about any one of those components are usually concerned with two categories of questions, one relating to the origins of the component and the other to its impact on the evolution of human cognition and social life. Remarkably few studies have been concerned with the evolution of the entity that integrates all components, the human social system itself. That social system has as its core feature human social structure, which I define here as the common denominator of all human societies in terms of group composition, mating system, residence patterns, and kinship structures. The paucity of information on the evolution of human social structure poses substantial problems because that information is useful, if not essential, to assess both the origins and impact of any particular aspect of human society. © 2013 Wiley Periodicals, Inc.

Maillard D.,Columbia University | Kumar S.K.,Columbia University | Rungta A.,University of South Carolina | Benicewicz B.C.,University of South Carolina | Prud'Homme R.E.,University of Montreal
Nano Letters | Year: 2011

We have studied the surface behavior of nanoparticles, which are lightly grafted with polymer chains, when they are mixed with matrix chains of the same architecture as the grafts. We consider the particular case where the nanoparticle core and the grafted polymer chains energetically dislike each other and show that the extent of surface segregation of these "hairy" nanoparticles and their self-assembly into a variety of structures can be tuned by varying the number and the length of the grafted chains and the matrix chain length. These results unequivocally show that grafted nanoparticles in polymer matrices behave akin to block copolymers (or amphiphiles) in selective solvents, with readily controllable surface behavior. © 2011 American Chemical Society.

Mandl J.N.,U.S. National Institutes of Health | Mandl J.N.,McGill University | Ahmed R.,Emory University | Barreiro L.B.,University of Montreal | And 4 more authors.
Cell | Year: 2015

Zoonotic viruses, such as HIV, Ebola virus, coronaviruses, influenza A viruses, hantaviruses, or henipaviruses, can result in profound pathology in humans. In contrast, populations of the reservoir hosts of zoonotic pathogens often appear to tolerate these infections with little evidence of disease. Why are viruses more dangerous in one species than another? Immunological studies investigating quantitative and qualitative differences in the host-virus equilibrium in animal reservoirs will be key to answering this question, informing new approaches for treating and preventing zoonotic diseases. Integrating an understanding of host immune responses with epidemiological, ecological, and evolutionary insights into viral emergence will shed light on mechanisms that minimize fitness costs associated with viral infection, facilitate transmission to other hosts, and underlie the association of specific reservoir hosts with multiple emerging viruses. Reservoir host studies provide a rich opportunity for elucidating fundamental immunological processes and their underlying genetic basis, in the context of distinct physiological and metabolic constraints that contribute to host resistance and disease tolerance. © 2015 Elsevier Inc. All rights reserved.

Charbonneau P.,University of Montreal
Living Reviews in Solar Physics | Year: 2010

This paper reviews recent advances and current debates in modeling the solar cycle as a hydromagnetic dynamo process. Emphasis is placed on (relatively) simple dynamo models that are nonetheless detailed enough to be comparable to solar cycle observations. After a brief overview of the dynamo problem and of key observational constraints, we begin by reviewing the various magnetic field regeneration mechanisms that have been proposed in the solar context. We move on to a presentation and critical discussion of extant solar cycle models based on these mechanisms. We then turn to the origin and consequences of fluctuations in these models, including amplitude and parity modulation, chaotic behavior, intermittency, and predictability. The paper concludes with a discussion of our current state of ignorance regarding various key questions relating to the explanatory framework offered by dynamo models of the solar cycle. © Max-Planck-Gesellschaft.

Gaudreault F.,University of Montreal
Anesthesia and Analgesia | Year: 2015

BACKGROUND:: Even though current perception threshold (CPT) has been used for evaluating the effectiveness of sensory block in patients before surgery, its reliability under controlled conditions has not been investigated. Two independent investigations were performed. The primary objective of the first study was to determine the test-retest reliability of CPT measures after repeated stimulations in a group of healthy volunteers. The primary objective of the second study was to evaluate the clinical applicability of this technique to assess the sensory onset of a femoral nerve block in patients undergoing knee surgery.RESULTS:: Within-day ICC values ranged (% confidence interval [CI]) from 0.66 to 0.95 with a CVSEM of approximately 39% (% CI: 17%–58%). Between-day ICC values, ranging from 0.57 to 0.94 (CVSEM: approximately 45%, % CI: 13%–71%), indicated that day-to-day CPT measurements are also variable. The current intensity needed for sensory perception in orthopedic patients significantly increased, varying from a mean CPT value of 82.5 ± 66.5 μA (SD) at time zero to an average of 481 ± 338 μA, 22 ± 8 minutes after the administration of the local anesthetic.METHODS:: Thirty healthy subjects participated in 2 identical sessions, separated by at least 24 hours, in which CPTs were measured after 5 consecutive stimulations over the anteromedial aspect of the thigh. Similar measures were obtained in 15 orthopedic patients receiving a femoral nerve block with 20 mL of ropivacaine 0.5%. Test-retest reliability was assessed using intraclass correlation (ICC) and standard error of measurement (expressed as coefficient of variation [CVSEM]), whereas Student t test (P < 0.05) compared the increase in CPTs over baseline.CONCLUSIONS:: CPT proved to be a reliable assessment tool for within-day sensory perception in healthy volunteers. Our study also suggests that CPT can be applied to characterize, in a quantitative manner, the sensory onset of a peripheral nerve block in a clinical setting, thereby supporting its use in future studies comparing different regional anesthetic modalities or approaches. © 2015 International Anesthesia Research Society

Foraging speed is a key determinant of fitness affecting both foraging success and predator attack survival. In a scramble for food, for instance, evolutionary stable strategy models predict that speed should increase with competitor density and decrease when the risk of attack by predators increases. Foraging speed should also decrease in richer food patches where the level of competition is reduced. I tested these predictions in fall staging flocks of semipalmated sandpipers (Calidris pusilla) foraging for an evasive prey. Capture rate of these prey decreased with sandpiper density as the presence of competitors reduced the availability of resources for those behind. Foraging speed was evaluated indirectly by measuring the time needed to cross fixed boundaries on mudflats over 6 years. As predicted, foraging speed increased with sandpiper density and decreased with food density, but, unexpectedly, increased closer to obstructive cover where predation risk was deemed higher. When foraging closer to cover, from where predators launch surprise attacks, the increase in foraging speed may compensate for an increase in false alarms that interrupted foraging. While foraging in denser flocks decreases foraging success, joining such flocks may also increase safety against predators. In semipalmated sandpipers that occupy an intermediate position in the food chain, foraging behavior is influenced simultaneously by the evasive responses of their prey and by the risk of attack from their own predators. © 2012 Springer-Verlag.

Nicoli F.,Marseille University Hospital Center | Lafaye De Micheaux P.,University of Montreal | Girard N.,Marseille University Hospital Center
American Journal of Neuroradiology | Year: 2013

BACKGROUND AND PURPOSE: Recent studies highlight the role of CC in preserving ischemic penumbra. Some authors suggested the quality of CC could also impact recanalization. The purpose of this study is to test this hypothesis in patients who were treated with IV thrombolysis for MCA-M1 occlusion. MATERIALS AND METHODS: A normalized index derived from Tmax maps (MR-PWI) was defined to quantify the CC deficit (nCCD) in 64 patients with stroke who underwent IV thrombolysis. Correlations between nCCD and parameters that may be altered by CC quality were tested (baseline NIHSS, volume of diffusion abnormalities, modified Rankin Scale at 3 months). The correlation between baseline nCCD and MCA-M1 recanalization rate at 24 hours was tested. RESULTS: The nCCD is significantly correlated with NIHSS and with lesional volume (Pearson correlation test, positive correlations, respectively, 0.40, 0.57; P=.00089, P=8.7e-07). The nCCD also has a significant predictive value on the full recanalization at 24 hours that decreases as TTT increases (logistic regression, P = .021). Furthermore, among patients who were treated within 3 hours, nCCD and recanalization are significantly correlated (correlation ratio test, eta2 = 0.23, P = .0023): Patients who did not achieve full recanalization have significantly higher nCCD than fully recanalized patients (Mann-Whitney U test, P = .007). In addition, the probability of full recanalization decreases as the nCCD increases (P=.021). nCCD (OR 0.988, 95% CI 0.977-0.999, P=.042) and full recanalization at 24 hours (OR 4.539, 95% CI 1.252-16.456, P = .021) are independent predictors of functional independence at 3 months. CONCLUSIONS: The nCCD index is a predictor of full MCA-M1 recanalization in patients treated with IV thrombolysis.

Legendre P.,University of Montreal | Fortin M.,University of Toronto
Molecular Ecology Resources | Year: 2010

The Mantel test is widely used to test the linear or monotonic independence of the elements in two distance matrices. It is one of the few appropriate tests when the hypothesis under study can only be formulated in terms of distances; this is often the case with genetic data. In particular, the Mantel test has been widely used to test for spatial relationship between genetic data and spatial layout of the sampling locations. We describe the domain of application of the Mantel test and derived forms. Formula development demonstrates that the sum-of-squares (SS) partitioned in Mantel tests and regression on distance matrices differs from the SS partitioned in linear correlation, regression and canonical analysis. Numerical simulations show that in tests of significance of the relationship between simple variables and multivariate data tables, the power of linear correlation, regression and canonical analysis is far greater than that of the Mantel test and derived forms, meaning that the former methods are much more likely than the latter to detect a relationship when one is present in the data. Examples of difference in power are given for the detection of spatial gradients. Furthermore, the Mantel test does not correctly estimate the proportion of the original data variation explained by spatial structures. The Mantel test should not be used as a general method for the investigation of linear relationships or spatial structures in univariate or multivariate data. Its use should be restricted to tests of hypotheses that can only be formulated in terms of distances. © 2010 Blackwell Publishing Ltd.

Teitelbaum S.,University of Montreal
Journal of Environmental Management | Year: 2014

In Canada, there are few structured evaluations of community forestry despite more than twenty years of practice. This article presents a criteria and indicator framework, designed to elicit descriptive information about the types of socio-economic results being achieved by community forests in the Canadian context. The criteria and indicators framework draws on themes proposed by other researchers both in the field of community forestry and related areas. The framework is oriented around three concepts described as amongst the underlying objectives of community forestry, namely participatory governance, local economic benefits and multiple forest use. This article also presents the results of a field-based application of the criteria and indicators framework, comparing four case studies in three Canadian provinces. All four are community forests with direct tenure rights to manage and benefit from forestry activities. Results reveal that in terms of governance, the case studies adhere to two different models, which we name 'interest group' vs. 'local government'. Stronger participatory dimensions are evident in two case studies. In the area of local economic benefits, the four case studies perform similarly, with some of the strongest benefits being in employment creation, especially for those case studies that offer non-timber activities such as recreation and education. Two of four cases have clearly adopted a multiple-use approach to management. © 2013 Elsevier Ltd.

Carpentier N.,University of Montreal | Grenier A.,McGill University
Qualitative Health Research | Year: 2012

Health interventions are currently being revamped to address the specific needs of chronic illness and population aging. In this context, focus has increasingly turned to Alzheimer-type dementia, an illness that is considered to mobilize a large number of social actors into long-term involvement of varying intensity. Linkage problems between families and professional systems have been well documented, yet the reasons for this remain relatively unexplored. In this article, we outline how we used social network data and narrative methods to better understand the linkage processes between formal and informal care systems. We present the trajectories of four caregivers of people suffering from Alzheimer's disease who were able to establish relationships with resources outside the family. In each of the cases, the dimensions of trust and recognition were central to establishing and maintaining supportive relationships, and must therefore be understood in light of social network dynamics and the broader environment. Although preliminary, this study contributes to the state of knowledge on linkage problems by proposing "bottom-up" solutions that are client centered. © The Author(s) 2012.

Donati F.,University of Montreal
Canadian Journal of Anesthesia | Year: 2013

Purpose: Over the past three decades, many studies have shown a high proportion of patients in the recovery room with residual neuromuscular blockade after anesthesia. The purpose of this Continuing Professional Development module is to present the physiological consequences of residual paralysis, estimate the extent of the problem, and suggest solutions to prevent its occurrence. Principal findings: Residual paralysis is defined as a train-of-four ratio (TOFR) < 0.9 at the adductor pollicis. While tidal volume and, to a lesser extent, vital capacity are well preserved as the intensity of blockade increases, the probability of airway obstruction, impaired swallowing, and pulmonary aspiration increases markedly as TOFR decreases. In recent studies, incidences of residual paralysis from 4-57% have been reported, but surveys indicate that anesthesiologists estimate the incidence of the problem at 1% or less. The decision to administer neostigmine or sugammadex should be based on the degree of spontaneous recovery at the adductor pollicis muscle (thumb), not on recovery at the corrugator supercilii (eyebrow). The most important drawback of neostigmine is its inability to reverse profound blockade, which is a consequence of its ceiling effect. When spontaneous recovery reaches the point where TOFR > 0.4 or four equal twitch responses are seen, reduced doses of neostigmine may be given. The dose of sugammadex required in a given situation depends on the intensity of blockade. Conclusion: Careful monitoring and delaying the administration of neostigmine until four twitches are observed at the adductor pollicis can decrease the incidence of residual paralysis. The clinical and pharmacoeconomic effects of unrestricted sugammadex use are unknown at this time. © 2013 Canadian Anesthesiologists' Society.

Pennestri M.H.,University of Montreal
Sleep medicine | Year: 2013

Periodic leg movements during sleep (PLMS) are associated with important blood pressure (BP) increases in restless legs syndrome (RLS) patients. These movements also are highly prevalent in the healthy elderly population. The aims of our study were to evaluate if heart rate (HR) and BP changes associated with PLMS are present in healthy subjects with no report of health concerns and to compare the amplitude of cardiovascular changes in healthy subjects to that of RLS subjects. Fourteen healthy subjects (six men, eight women; 46.6±9.7 y) and 14 RLS subjects (six men, eight women; 47.6±11.8 y) matched for age and gender participated in our study. Beat-to-beat noninvasive BP was continuously recorded during one night of polysomnography. HR, systolic BP (SBP) and diastolic BP (DBP) were measured for 10 beats before and 15 beats after onset of PLMS with and without microarousals (MA). PLMS were associated with sudden and significant increases of HR, SBP and DBP in both groups; however, cardiovascular increases were more pronounced in RLS subjects than in healthy subjects. Because PLMS index increases with age in healthy subjects and aging is associated with higher cardiovascular risk, further studies should investigate the impact of PLMS-related BP changes on the development of cardiovascular diseases in healthy elderly populations. Copyright © 2013 Elsevier B.V. All rights reserved.

Archambault V.,University of Montreal | Carmena M.,University of Edinburgh
Cell Cycle | Year: 2012

The events of cell division are regulated by a complex interplay between kinases and phosphatases. Cyclin-dependent kinases (Cdks), Polo-like kinases (Plks) and Aurora kinases play central roles in this process. Polo kinase (Plk1 in humans) regulates a wide range of events in mitosis and cytokinesis. To ensure the accuracy of these processes, Polo activity itself is subject to complex regulation. Phosphorylation of Polo in its T loop (or activation loop) increases its kinase activity several-fold. It has been shown that Aurora A kinase, with its co-factor Bora, activates Plk1 in G2, and that this is essential for recovery from cell cycle arrest induced by DNA damage. In a recent article published in PLoS Biology, we report that Drosophila Polo is activated by Aurora B kinase at centromeres, and that this is crucial for Polo function in regulating chromosome dynamics in prometaphase. Our results suggest that this regulatory pathway is conserved in humans. Here, we propose a model for the collaboration between Aurora B and Polo in the regulation of kinetochore attachment to microtubules in early mitosis. Moreover, we suggest that Aurora B could also function to activate Polo/Plk1 in cytokinesis. Finally, we discuss recent findings and open questions regarding the activation of Polo and Polo-like kinases by different kinases in mitosis, cytokinesis and other processes. © 2012 Landes Bioscience.

Yergeau E.,National Research Council Canada | Sanschagrin S.,National Research Council Canada | Maynard C.,National Research Council Canada | St-Arnaud M.,University of Montreal | Greer C.W.,National Research Council Canada
ISME Journal | Year: 2014

The goal of phytoremediation is to use plants to immobilize, extract or degrade organic and inorganic pollutants. In the case of organic contaminants, plants essentially act indirectly through the stimulation of rhizosphere microorganisms. A detailed understanding of the effect plants have on the activities of rhizosphere microorganisms could help optimize phytoremediation systems and enhance their use. In this study, willows were planted in contaminated and non-contaminated soils in a greenhouse, and the active microbial communities and the expression of functional genes in the rhizosphere and bulk soil were compared. Ion Torrent sequencing of 16S rRNA and Illumina sequencing of mRNA were performed. Genes related to carbon and amino-acid uptake and utilization were upregulated in the willow rhizosphere, providing indirect evidence of the compositional content of the root exudates. Related to this increased nutrient input, several microbial taxa showed a significant increase in activity in the rhizosphere. The extent of the rhizosphere stimulation varied markedly with soil contamination levels. The combined selective pressure of contaminants and rhizosphere resulted in higher expression of genes related to competition (antibiotic resistance and biofilm formation) in the contaminated rhizosphere. Genes related to hydrocarbon degradation were generally more expressed in contaminated soils, but the exact complement of genes induced was different for bulk and rhizosphere soils. Together, these results provide an unprecedented view of microbial gene expression in the plant rhizosphere during phytoremediation.

Thomas F.,IRD Montpellier | Poulin R.,University of Otago | Brodeur J.,University of Montreal
Oikos | Year: 2010

The diversity of ways in which parasites manipulate the phenotype of their hosts to increase their transmission has been well-documented during the past decades. Parasites clearly have the potential to alter a broad range of phenotypic traits in their hosts, extending from behaviour and colour to morphology and physiology. While the vast majority of studies have concentrated on few, often only one, host characters, there is increasing evidence that manipulative parasites alter multiple characteristics of their host's phenotype. These alterations can occur simultaneously and/or successively through time, making parasitically modified organisms undoubtedly more complex than traditionally viewed. Here, we briefly review the multidimensionality of host manipulation by parasites, discuss its possible significance and evolution, and propose directions for further research. This view should prove to be an extremely useful approach, generating a series of testable hypotheses regarding the ecology of parasitized hosts, and leading to a better comprehension of complex host-parasite relationships. © 2009 The Authors.

Bhandari P.,University of Washington | Song M.,University of Washington | Chen Y.,University of Washington | Burelle Y.,University of Montreal | Dorn G.W.,University of Washington
Circulation Research | Year: 2014

Rationale: Dysfunctional Parkin-mediated mitophagic culling of senescent or damaged mitochondria is a major pathological process underlying Parkinson disease and a potential genetic mechanism of cardiomyopathy. Despite epidemiological associations between Parkinson disease and heart failure, the role of Parkin and mitophagic quality control in maintaining normal cardiac homeostasis is poorly understood. Objective: We used germline mutants and cardiac-specific RNA interference to interrogate Parkin regulation of cardiomyocyte mitochondria and examine functional crosstalk between mitophagy and mitochondrial dynamics in Drosophila heart tubes. Methods and Results: Transcriptional profiling of Parkin knockout mouse hearts revealed compensatory upregulation of multiple related E3 ubiquitin ligases. Because Drosophila lack most of these redundant genes, we examined heart tubes of parkin knockout flies and observed accumulation of enlarged hollow donut mitochondria with dilated cardiomyopathy, which could be rescued by cardiomyocyte-specific Parkin expression. Identical abnormalities were induced by cardiomyocyte-specific Parkin suppression using 2 different inhibitory RNAs. Parkin-deficient cardiomyocyte mitochondria exhibited dysmorphology, depolarization, and reactive oxygen species generation without calcium cycling abnormalities, pointing to a primary mitochondrial defect. Suppressing cardiomyocyte mitochondrial fusion in Parkin-deficient fly heart tubes completely prevented the cardiomyopathy and corrected mitochondrial dysfunction without normalizing mitochondrial dysmorphology, demonstrating a central role for mitochondrial fusion in the cardiomyopathy provoked by impaired mitophagy. Conclusions: Parkin deficiency and resulting mitophagic disruption produces cardiomyopathy in part by contamination of the cardiomyocyte mitochondrial pool through fusion between improperly retained dysfunctional/ senescent and normal mitochondria. Limiting mitochondrial contagion by inhibiting organelle fusion shows promise for minimizing organ dysfunction produced by defective mitophagic signaling. © 2013 American Heart Association, Inc.

Davidson C.,University of Montreal
Construction Innovation | Year: 2013

Purpose - This paper aims to present an overview of innovation in the construction sector, its forms, its inherent pitfalls and difficulties, and some underlying reasons for them. The familiar distinction between technical and organisational innovation is inapplicable in the fragmented construction industry. Design/methodology/approach - This paper is based on systematic observation, accompanying many years' hands-on experience. Findings - The processes of innovation in construction require that the innovator (possibly starting from a narrow idea or opportunity) broaden his/her view to take into account the impacts of the intended innovation on the priorities of other stakeholders, in an iterative process. In other words, orchestrated organisational changes must accompany - if not precede - technical innovation. Research limitations/implications - This paper specifically describes the processes and constraints of innovation in the context of the construction sector. Practical implications - Failure to take into account the dual obligation to innovate simultaneously on the organisational and technical fronts will lead to yet one more failed attempt. Such a failure represents a waste of time and effort, and a missed opportunity to contribute to improved construction. Originality/value - This paper is based on a uniquely broad experience-based view of innovation, covering a period of more than five decades; this feedback from experience can help innovators directly and provide evidence for subsequent research. © Emerald Group Publishing Limited.

Objective: To determine whether therapeutic yoga improves the quality of life of patients with cancer. Data sources: Search of MEDLINE database (1950-2010) using key words yoga, cancer, and quality of life. Study selection: Priority was given to randomized controlled clinical studies conducted to determine the effect of yoga on typical symptoms of patients with cancer in North America. Synthesis: Initially, 4 randomized controlled clinical studies were analyzed, then 2 studies without control groups were analyzed. Three studies conducted in India and the Near East provided interesting information on methodologies. The interventions included yoga sessions of varying length and frequency. The parameters measured also varied among studies. Several symptoms improved substantially with yoga (higher quality of sleep, decrease in symptoms of anxiety and depression, improvement in spiritual well-being, etc). It would appear that quality of life, or some aspects thereof, also improved. Conclusion: The variety of benefits derived, the absence of side effects, and the cost-benefit ratio of therapeutic yoga make it an interesting alternative for family physicians to suggest to their patients with cancer. Certain methodologic shortcomings, including the limited size of the samples and varying levels of attendance on the part of the subjects, might have reduced the statistical strength of the studies presented. It is also possible that the measurement scales used did not suit this type of situation and patient population, making it impossible to see a significant effect. However, favourable comments by participants during the studies and their level of appreciation and well-being suggest that further research is called for to fully understand the mechanisms of these effects.

Shechter A.,McGill University | Varin F.,University of Montreal | Boivin D.B.,McGill University
Sleep | Year: 2010

Study Objectives: Women experience insomnia more frequently than men. Menstrual cycle changes in reproductive hormones and circadian rhythms may contribute to sleep disruptions. Our aim, therefore, was to clarify the interaction between menstrual and circadian processes as it affects sleep. Design: Participants entered the laboratory during the mid-follicular (MF) and mid-luteal (ML) phases of their menstrual cycle for an ultra-rapid sleep-wake cycle (URSW) procedure, consisting of 36 cycles of 60-min wake episodes alternating with 60-min nap opportunities. This procedure concluded with an ad libitum nap episode. Setting: Time-isolation suite. Participants: Eight unmedicated, physically and mentally healthy females with regular ovulatory menstrual cycles. Interventions: N/A Measurements: Polysomnographic sleep from nocturnal sleep episodes and 60-min naps; subjective alertness; core body temperature (CBT); salivary melatonin; urinary estradiol; and urinary progesterone. Results: Increased CBT values at night and decreased CBT amplitude were observed during ML compared to MF. Circadian phase of CBT and the circadian melatonin profile were unaffected by menstrual phase. All analyzed sleep parameters showed a circadian variation throughout the URSW procedure, with no menstrual phase differences observed for most, including slow wave sleep (SWS). The circadian variation of REM sleep duration, however, was sensitive to menstrual phase, with reduced REM sleep during ML at circadian phase 0° and 30°. Conclusions: Moderate but significant changes in REM sleep across the menstrual and circadian cycles were observed. These results support an interaction between circadian and menstrual processes in the regulation of REM sleep.

Cartier A.,University of Montreal
Current Opinion in Allergy and Clinical Immunology | Year: 2015

Purpose of review The objective of this study was to review all new causes of well documented immunologic occupational asthma (IOA) published in the English and French medical literature between January 2012 and mid-2014.Recent findings Ten case reports of new causes of IOA were reported during that period. The diagnosis was either confirmed by specific inhalation challenges (n = 5) or a combination of peak expiratory flow monitoring at and off work, confirmation of specific sensitisation, and asthma (n = 3). These involved both high (mites contaminating cured ham, various enzymes used as detergents and food additives, aquarium fish food, and orange allergens) and low-molecular-weight agents (spruce wood dust, a biocide, and an halogenated platinum compound used in cytotoxic drugs). Furthermore, eight studies reported cases of IOA with agents already known as airway sensitizers but in working environments that were unusual and reported for the first time.Summary There are more than 400 known causes of IOA and the list grows continuously with the development of new technologies and better recognition of the diagnosis by physicians. IgE-mediated sensitization was confirmed in all new cases involving high-molecular-weight agents and in two of the three new cases involving low-molecular-weight agents. Symptoms of rhinitis were often associated with both types of agents. Physicians should stay alert and suspect occupational asthma in any adult with new-onset asthma or with newly uncontrolled asthma. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.

Nielsen T.,University of Montreal
Behavioral and Brain Sciences | Year: 2013

Certain method of loci (MoL) prerequisites-familiar, coherently ordered locations-should appear during dreaming if the latter is, in fact, elaborative memory encoding as hypothesized by Llewellyn. A review of the literature suggests that dreamed locations are neither familiar nor coherently ordered and thus unsuitable for facilitating memory in this sense. This conclusion converges with other evidence that episodic memory is dependent upon non-rapid eye movement (NREM), rather than REM, sleep. © 2013 Cambridge University Press.

Banquy X.,University of Montreal | Burdynska J.,Carnegie Mellon University | Lee D.W.,University of California at Santa Barbara | Matyjaszewski K.,Carnegie Mellon University | Israelachvili J.,University of California at Santa Barbara
Journal of the American Chemical Society | Year: 2014

We report the design of a bottle-brush polymer whose architecture closely mimics the lubricating protein lubricin. Interaction forces, assessed using a Surface Forces Apparatus (SFA), between two mica surfaces fully covered by the polymer demonstrate that the polymer adopts a loop conformation giving rise to a weak and long-range repulsive interaction force between the surfaces. Under high compression, stronger repulsive forces appear due to the strong compression of the grafted pendant chains of the polymer. When submitted to shear, the system shows extremely low frictional forces dependent on the salinity of the medium. Friction coefficients measured for this system were as low as ∼10-3. Interestingly, the confined lubricating fluid obeys all three Amontons? laws. We explain this peculiar observation by the strong shear thinning of the confined fluid and the osmotic repulsive forces that dominate the overall (dynamic and equilibrium) surface interactions. © 2014 American Chemical Society.

Renaut S.,University of British Columbia | Renaut S.,University of Montreal | Rieseberg L.H.,University of British Columbia | Rieseberg L.H.,Indiana University Bloomington
Molecular Biology and Evolution | Year: 2015

For populations to maintain optimal fitness, harmful mutations must be efficiently purged from the genome. Yet, under circumstances that diminish the effectiveness of natural selection, such as the process of plant and animal domestication, deleteriousmutations are predicted to accumulate. Here, we compared the load of deleterious mutations in 21 accessions from natural populations and 19 domesticated accessions of the common sunflower using whole-transcriptome single nucleotide polymorphism data. Although we find that genetic diversity has been greatly reduced during domestication, the remaining mutations were disproportionally biased toward nonsynonymous substitutions. Bioinformatically predicted deleteriousmutations affecting protein function were especially strongly over-represented.We also identify similar patterns in two other domesticated species of the sunflower family (globe artichoke and cardoon), indicating that this phenomenon is not due to idiosyncrasies of sunflower domestication or the sunflower genome. Finally, we provide unequivocal evidence that deleterious mutations accumulate in low recombining regions of the genome, due to the reduced efficacy of purifying selection. These results represent a conundrum for crop improvement efforts. Although the elimination of harmful mutations should be a long-term goal of plant and animal breeding programs, it will be difficult to weed them out because of limited recombination. © 2015 The Author.

Idili A.,University of Rome Tor Vergata | Idili A.,Italian National Institute of Biosystems and Biostructures | Vallee-Belisle A.,University of Montreal | Ricci F.,University of Rome Tor Vergata | Ricci F.,Italian National Institute of Biosystems and Biostructures
Journal of the American Chemical Society | Year: 2014

We have designed programmable DNA-based nanoswitches whose closing/opening can be triggered over specific different pH windows. These nanoswitches form an intramolecular triplex DNA structure through pH-sensitive parallel Hoogsteen interactions. We demonstrate that by simply changing the relative content of TAT/CGC triplets in the switches, we can rationally tune their pH dependence over more than 5 pH units. The ability to design DNA-based switches with tunable pH dependence provides the opportunity to engineer pH nanosensors with unprecedented wide sensitivity to pH changes. For example, by mixing in the same solution three switches with different pH sensitivity, we developed a pH nanosensor that can precisely monitor pH variations over 5.5 units of pH. With their fast response time (<200 ms) and high reversibility, these pH-triggered nanoswitches appear particularly suitable for applications ranging from the real-time monitoring of pH changes in vivo to the development of pH sensitive smart nanomaterials. © 2014 American Chemical Society.

Hilgert J.A.,University of Montreal
American Journal of Industrial Medicine | Year: 2012

Background: This article introduces the idea of human rights to the topic of workers' compensation in the United States. It discusses what constitutes a human rights approach and explains how this approach conflicts with those policy ideas that have provided the foundation historically for workers' compensation in the United States. Methods: Using legal and historical research, key international labor and human rights standards on employment injury benefits and influential writings in the development of the U.S. workers' compensation system are cited. Results: Workers' injury and illness compensation in the United States does not conform to basic international human rights norms. Conclusions: A comprehensive review of the U.S. workers' compensation system under international human rights standards is needed. Examples of policy changes are highlighted that would begin the process of moving workers' compensation into conformity with human rights standards. © 2012 Wiley Periodicals, Inc.

Sankoff D.,University of Ottawa | Zheng C.,University of Montreal | Zhu Q.,Princeton University
BMC Genomics | Year: 2010

Background: Genome amplification through duplication or proliferation of transposable elements has its counterpart in genome reduction, by elimination of DNA or by gene inactivation. Whether loss is primarily due to excision of random length DNA fragments or the inactivation of one gene at a time is controversial. Reduction after whole genome duplication (WGD) represents an inexorable collapse in gene complement.Results: We compare fifteen genomes descending from six eukaryotic WGD events 20-450 Mya. We characterize the collapse over time through the distribution of runs of reduced paralog pairs in duplicated segments. Descendant genomes of the same WGD event behave as replicates. Choice of paralog pairs to be reduced is random except for some resistant regions of contiguous pairs. For those paralog pairs that are reduced, conserved copies tend to concentrate on one chromosome.Conclusions: Both the contiguous regions of reduction-resistant pairs and the concentration of runs of single copy genes on a single chromosome are evidence of transcriptional co-regulation, dosage sensitivity or other functional interaction constraining the reduction process. These constraints and their evolution over time show a consistent pattern across evolutionary domains and a highly reproducible pattern, as replicates, for the several descendants of a single WGD. © 2010 Sankoff et al; licensee BioMed Central Ltd.

Thomas A.,University of Lausanne | Chaurand P.,University of Montreal
Bioanalysis | Year: 2014

Enriched by a decade of remarkable developments, matrix-assisted laser desorption ionization imaging mass spectrometry (MALDI IMS) has witnessed a phenomenal expansion. Initially introduced for the mapping of peptides and intact proteins from mammalian tissue sections, MALDI IMS applications now extend to a wide range of molecules including peptides, lipids, metabolites and xenobiotics. Technology and methodology are quickly evolving to push the limits of the technique forward. Within a short period of time, numerous protocols and concepts have been developed and introduced in tissue section preparation, nonexhaustively including in situ tissue chemistries and solvent-free matrix depositions. Considering the past progress and current capabilities, this Review aims to cover the different aspects and challenges of tissue section preparation for MALDI IMS. © 2014 Future Science Ltd.

Galazyuk A.,Northeast Ohio Medical University | Hebert S.,University of Montreal
Frontiers in Neurology | Year: 2015

The progress in the field of tinnitus largely depends on the development of a reliable tinnitus animal model. Recently, a new method based on the acoustic startle reflex modification was introduced for tinnitus screening in laboratory animals. This method was enthusiastically adopted and now widely used by many scientists in the field due to its seeming simplicity and a number of advantages over the other methods of tinnitus assessment. Furthermore, this method opened an opportunity for tinnitus assessment in humans as well. Unfortunately, multiple modifications of data collection and interpretation implemented in different labs make comparisons across studies very difficult. In addition, recent animal and human studies have challenged the original "filling-in" interpretation of the paradigm. Here, we review the current literature to emphasize on the commonalities and differences in data collection and interpretation across laboratories that are using this method for tinnitus assessment. We also propose future research directions that could be taken in order to establish whether or not this method is warranted as an indicator of the presence of tinnitus. © 2015 Galazyuk and Hébert.

Fakhoury M.,University of Montreal
Reviews in the Neurosciences | Year: 2015

Spinal cord injury affects more than 2.5 million people worldwide and can lead to paraplegia and quadriplegia. Anatomical discontinuity in the spinal cord results in disruption of the impulse conduction that causes temporary or permanent changes in the cord's normal functions. Although axonal regeneration is limited, damage to the spinal cord is often accompanied by spontaneous plasticity and axon regeneration that help improve sensory and motor skills. The recovery process depends mainly on synaptic plasticity in the preexisting circuits and on the formation of new pathways through collateral sprouting into neighboring denervated territories. However, spontaneous recovery after spinal cord injury can go on for several years, and the degree of recovery is very limited. Therefore, the development of new approaches that could accelerate the gain of motor function is of high priority to patients with damaged spinal cord. Although there are no fully restorative treatments for spinal injury, various rehabilitative approaches have been tested in animal models and have reached clinical trials. In this paper, a closer look will be given at the potential therapies that could facilitate axonal regeneration and improve locomotor recovery after injury to the spinal cord. This article highlights the application of several interventions including locomotor training, molecular and cellular treatments, and spinal cord stimulation in the field of rehabilitation research. Studies investigating therapeutic approaches in both animal models and individuals with injured spinal cords will be presented. © 2015 by De Gruyter 2015.

Araya R.,University of Montreal
Frontiers in Neuroanatomy | Year: 2014

In the mammalian brain, most inputs received by a neuron are formed on the dendritic tree. In the neocortex, the dendrites of pyramidal neurons are covered by thousands of tiny protrusions known as dendritic spines, which are the major recipient sites for excitatory synaptic information in the brain. Their peculiar morphology, with a small head connected to the dendritic shaft by a slender neck, has inspired decades of theoretical and more recently experimental work in an attempt to understand how excitatory synaptic inputs are processed, stored and integrated in pyramidal neurons. Advances in electrophysiological, optical and genetic tools are now enabling us to unravel the biophysical and molecular mechanisms controlling spine function in health and disease. Here I highlight relevant findings, challenges and hypotheses on spine function, with an emphasis on the electrical properties of spines and on how these affect the storage and integration of excitatory synaptic inputs in pyramidal neurons. In an attempt to make sense of the published data, I propose that the raison d'etre for dendritic spines lies in their ability to undergo activity-dependent structural and molecular changes that can modify synaptic strength, and hence alter the gain of the linearly integrated sub-threshold depolarizations in pyramidal neuron dendrites before the generation of a dendritic spike. © 2014 Araya.

Cameron C.B.,University of Montreal | Bishop C.D.,St. Francis Xavier University
Proceedings of the Royal Society B: Biological Sciences | Year: 2012

Here, we report the discovery and characterization of biominerals in the acorn worms Saccoglossus bromophenolosus and Ptychodera flava galapagos (Phylum:Hemichordata).Using electron microscopy, X-ray microprobe analyses and confocal Raman spectroscopy, we show that hemichordate biominerals are small CaCO3 aragonitic elements restricted to specialized epidermal structures, and in S. bromophenolosus, are apparently secreted by sclerocytes. Investigation of urchin biomineralizing proteins in the translated genome and expressed sequence tag (EST) libraries of Saccoglossus kowalevskii indicates that three members of the urchin MSP- 130 family, a carbonic anhydrase and a matrix metaloprotease are present and transcribed during the development of S. kowalevskii. The SMfamily of proteins is absent from the hemichordate genome. These results increase the number of phyla known to biomineralize and suggest that some of the gene-regulatory 'toolkit', if not mineralized tissue themselves, may have been present in the common ancestor to hemichordates and echinoderms. © 2012 The Royal Society.

Beauchamp G.,University of Montreal
Animal Behaviour | Year: 2012

How animals in groups coordinate their movements to produce cohesive collective patterns has been the subject of many models but remains poorly documented empirically in the field. I investigated waves of escape in flocks of a shorebird roosting on beaches to pinpoint factors that influence coordination in the initiation of group movements. In roosting flocks of semipalmated sandpipers, . Calidris pusilla, the escape of a single alarmed bird triggered similar responses in nearby companions, eventually propagating through the whole flock as a wave. Among flocks, wave speed through the whole flock increased with size but decreased with density over nearly three orders of magnitude in size and density. Large flocks are attacked more often by predators, and individuals in such groups may therefore respond more quickly to the escape of companions. The negative effect of density suggests that birds escaped more slowly in denser flocks to avoid collision. This interpretation is bolstered by the fact that wave speed increased with density at the edges of the flock, where the risk of collision is reduced. Waves propagated faster at the edges of the flock than through the whole flock, suggesting a selfish herd mechanism whereby edge individuals try to avoid being left behind or overtaken by others. Findings suggest that birds can integrate a host of factors to adjust escapes in a coherent fashion very rapidly. © 2012 The Association for the Study of Animal Behaviour.

Bertrand S.,University of Montreal
Journal of Physics: Conference Series | Year: 2016

The main aim of this paper is twofold. One is the construction and analysis of supersymmetric (bosonic and fermionic) versions of the structural equations for conformally parametrized surfaces. The other is the investigation of integrability in the sense of soliton theory via a comparison of the symmetries of the system of differential equations and those of the associated linear problem. This paper consists of an overview of the results obtained in two previous works [1, 2]. © Published under licence by IOP Publishing Ltd.

Barthelemy D.,Copenhagen University | Barthelemy D.,University of Montreal | Nielsen J.B.,Copenhagen University
Journal of Physiology | Year: 2010

When we walk, our arm muscles show rhythmic activity suggesting that the central nervous system contributes to the swing of the arms. The purpose of the present study was to investigate whether corticospinal drive plays a role in the control of arm muscle activity during human walking. Motor evoked potentials (MEPs) elicited in the posterior deltoid muscle (PD) by transcranial magnetic stimulation (TMS) were modulated during the gait cycle in parallel with changes in the background EMG activity. There was no significant difference in the size of the MEPs at a comparable level of background EMG during walking and during static PD contraction. Short latency intracortical inhibition (SICI; 2 ms interval) studied by paired-pulse TMS was diminished during bursts of PD EMG activity. This could not be explained only by changes in background EMG activity and/or control MEP size, since SICI showed no correlation to the level of background EMG activity during static PD contraction. Finally, TMS at intensity below the threshold for activation of corticospinal tract fibres elicited a suppression of the PD EMG activity during walking. Since TMS at this intensity is likely to only activate intracortical inhibitory interneurones, the suppression is in all likelihood caused by removal of a corticospinal contribution to the ongoing EMG activity. The data thus suggest that the motor cortex makes an active contribution, through the corticospinal tract, to the ongoing EMG activity in arm muscles during walking. © 2010 The Authors. Journal compilation © 2010 The Physiological Society.

Juul K.V.,Medical Science Urology | Bichet D.G.,University of Montreal | Nielsen S.,University of Aarhus | Norgaard J.P.,Medical Science Urology
American Journal of Physiology - Renal Physiology | Year: 2014

The arginine vasopressin (AVP) type 2 receptor (V2R) is unique among AVP receptor subtypes in signaling through cAMP. Its key function is in the kidneys, facilitating the urine concentrating mechanism through the AVP/V2 type receptor/aquaporin 2 system in the medullary and cortical collecting ducts. Recent clinical and research observations strongly support the existence of an extrarenal V2R. The clinical importance of the extrarenal V2R spans widely from stimulation of coagulation factor in the endothelium to as yet untested potential therapeutic targets. These include V2R-regulated membranous fluid turnover in the inner ear, V2R-regulated mitogensis and apoptosis in certain tumor tissues, and numerous other cell types where the physiological role of V2Rs still requires further research. Here, we review current evidence on the physiological and pathophysiological functions of renal and extrarenal V2Rs. These functions of V2R are important, not only in rare diseases with loss or gain of function of V2R but also in relation to the recent use of nonpeptide V2R antagonists to treat hyponatremia and possibly retard the growth of cysts and development of renal failure in autosomal dominant polycystic kidney disease. The main functions of V2R in principal cells of the collecting duct are water, salt, and urea transport by modifying the trafficking of aquaporin 2, epithelial Na+ channels, and urea transporters and vasodilation and stimulation of coagulation factor properties, mainly seen with pharmacological doses of 1-desamino-8-D-AVP. The AVPR2 gene is located on the X chromosome, in a region with high probability of escape from inactivation; this may lead to phenotypic sex differences, with females expressing higher levels of transcript than males. © 2014 the American Physiological Society.

Borden K.L.B.,University of Montreal
Cancer Research | Year: 2014

Cancer cells rapidly evolve a multitude of defense mechanisms to evade the effects of the oncologist's drug arsenal. Unfortunately, clinical strategies to overcome these lag far behind. This mismatch likely underlies our inability to implement new durable treatment strategies. Here, a new form of multidrug resistance, inducible drug glucuronidation, is discussed. This form was discovered while developing means to target a specific oncogene, the eukaryotic translation initiation factor 4E (eIF4E), with its inhibitor ribavirin. In two clinical studies, ribavirin treatment led to substantial clinical responses, but all responding patients eventually relapsed. In most cases, this was due to the overexpression of the sonic hedgehog transcription factor Gli1, which elevated the UDP glucuronsyltransferase UGT1A enzymes. UGT1As add glucuronic acid to many drugs. Indeed, these cells are resistant to not only ribavirin, but also Ara-C, and likely other drugs. Inhibition of Gli1 reduced UGT1As, eliminated drug glucuronides, and renewed sensitivity to ribavirin and Ara-C. These studies highlight that cancer cells and their resistant counterparts metabolize drugs differently from each other as well as from normal cells. Likely, these inducible modifications go beyond glucuronidation. Understanding the extent of inducible drug modifications and the pathways that drive expression of the corresponding enzymatic machinery will better position us to finally make resistance futile. © 2014 AACR.

Cohen E.A.,University of Montreal
Cell Host and Microbe | Year: 2014

HIV Vpr induces a cell-cycle arrest at the G2-to-M transition through a poorly understood mechanism. In a recent issue of Cell, Laguette et al. (2014) demonstrate that untimely activation of the structure-specific endonuclease regulator SLX4 complex by Vpr promotes G2/M arrest and escape from innate immune sensing. © 2014 Elsevier Inc.

Skeldon A.M.,McGill University | Faraj M.,University of Montreal | Saleh M.,McGill University
Immunology and Cell Biology | Year: 2014

Inflammation is an important contributor to the development of metabolic disease. Recent work has strongly implicated the inflammasome and caspase-1 as having a pivotal role in the regulation of metabolism, obesity, insulin resistance and cardiovascular disease. Through multiple murine and human studies we now know that the inflammasome can be activated by metabolic triggers in vivo. Clinical studies also reveal the inflammasome to be a potential candidate for therapeutic intervention and provide a clear incentive for future work on this inflammatory pathway. © 2014 Australasian Society for Immunology Inc. All rights reserved.

Charbonneau P.,University of Montreal
Annual Review of Astronomy and Astrophysics | Year: 2014

The Sun's magnetic field is the engine and energy source driving all phenomena collectively defining solar activity, which in turn structures the whole heliosphere and significantly impacts Earth's atmosphere down at least to the stratosphere. The solar magnetic field is believed to originate through the action of a hydromagnetic dynamo process operating in the Sun's interior, where the strongly turbulent environment of the convection zone leads to flow-field interactions taking place on an extremely wide range of spatial and temporal scales. Following a necessarily brief observational overview of the solar magnetic field and its cycle, this review on solar dynamo theory is structured around three areas in which significant advances have been made in recent years: (a) global magnetohydrodynamical simulations of convection and magnetic cycles, (b) the turbulent electromotive force and the dynamo saturation problem, and (c) flux transport dynamos, and their application to model cycle fluctuations and grand minima and to carry out cycle prediction. Copyright © 2014 by Annual Reviews.

Hunt M.R.,McGill University | Godard B.,University of Montreal
Global Public Health | Year: 2013

Interest in global health is growing among students across many disciplines and fields of study. In response, an increasing number of academic programmes integrate and promote opportunities for international research, service or clinical placements. These activities raise a range of ethical issues and are associated with important training needs for those who participate. In this paper, we focus on research fieldwork conducted in lower income nations by students from more affluent countries and the ethics preparation they would benefit from receiving prior to embarking on these projects. Global health research is closely associated with questions of justice and equity that extend beyond concerns of procedural ethics. Research takes place in and is shaped by matrices of political, social and cultural contexts and concerns. These realities warrant analysis and discussion during research ethics training. Training activities present an opportunity to encourage students to link global health research to questions of global justice, account for issues of justice in planning their own research, and prepare for 'ethics-in-practice' issues when conducting research in contexts of widespread inequality. Sustained engagement with questions of justice and equity during research ethics training will help support students for involvement in global health research. © 2013 © 2013 The Author(s). Published by Routledge.

Kobayashi T.,New York University | Tsang W.Y.,New York University | Tsang W.Y.,University of Montreal | Tsang W.Y.,McGill University | And 4 more authors.
Cell | Year: 2011

We have identified a protein, Kif24, that shares homology with the kinesin-13 subfamily of motor proteins and specifically interacts with CP110 and Cep97, centrosomal proteins that play a role in regulating centriolar length and ciliogenesis. Kif24 preferentially localizes to mother centrioles. Loss of Kif24 from cycling cells resulted in aberrant cilia assembly but did not promote growth of abnormally long centrioles, unlike CP110 and Cep97 depletion. We found that loss of Kif24 leads to the disappearance of CP110 from mother centrioles, specifically in cycling cells able to form cilia. Kif24 is able to bind and depolymerize microtubules in vitro. Remarkably, ectopically expressed Kif24 specifically remodels centriolar microtubules without significantly altering cytoplasmic microtubules. Thus, our studies have identified a centriolar kinesin that specifically remodels a subset of microtubules, thereby regulating cilia assembly. These studies also suggest mechanistic differences between the regulation of microtubule elongation associated with centrioles and cilia. © 2011 Elsevier Inc. All Rights Reserved.

Nolan C.J.,Australian National University | Ruderman N.B.,Boston University | Kahn S.E.,University of Washington | Pedersen O.,Novo Nordisk AS | Prentki M.,University of Montreal
Diabetes | Year: 2015

Stratifying the management of type 2 diabetes (T2D) has to take into account marked variability in patient phenotype due to heterogeneity in its pathophysiology, different stages of the disease process, and multiple other patient factors including comorbidities. The focus here is on the very challenging subgroup of patients with T2D who are overweight or obese with insulin resistance (IR) and the most refractory hyperglycemia due to an inability to change lifestyle to reverse positive energy balance. For this subgroup of patients with T2D, we question the dogma that IR is primarily harmful to the body and should be counteracted at any cost. Instead we propose that IR, particularly in this high-risk subgroup, is a defense mechanism that protects critical tissues of the cardiovascular system from nutrient-induced injury. Overriding IR in an effort to lower plasma glucose levels, particularly with intensive insulin therapy, could therefore be harmful. Treatments that nutrient off-load to lower glucose are more likely to be beneficial. The concepts of "IR as an adaptive defense mechanism" and "insulin-induced metabolic stress" may provide explanation for some of the unexpected outcomes of recent major clinical trials in T2D. Potential molecular mechanisms underlying these concepts; their clinical implications for stratification of T2D management, particularly in overweight and obese patients with difficult glycemic control; and future research requirements are discussed. © 2015 by the American Diabetes Association.

Caesarean section rates are over 20% in many developed countries. The main diagnosis contributing to the high rate in nulliparae is dystocia or prolonged labour. The present review assesses the effects of a policy of early amniotomy with early oxytocin administration for the prevention of, or the therapy for, delay in labour progress. To estimate the effects of early augmentation with amniotomy and oxytocin for prevention of, or therapy for, delay in labour progress on the caesarean birth rate and on indicators of maternal and neonatal morbidity. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 May 2013), MEDLINE (1966 to 4 July 2013), Embase (1980 to 4 July 2013), CINAHL (1982 to 4 July 2013), MIDIRS (1985 to 4 July 2013) and contacted authors for data from unpublished trials. Randomized and quasi-randomized controlled trials that compared oxytocin and amniotomy with expectant management. Three review authors extracted data independently. We stratified the analyses into 'Prevention Trials' and 'Therapy Trials' according to the status of the woman at the time of randomization. Participants in the 'Prevention Trials' were unselected women, without slow progress in labour, who were randomized to a policy of early augmentation or to routine care. In 'Treatment Trials' women were eligible if they had an established delay in labour progress. For the 2013 update, we identified and excluded one new clinical trial. This updated review includes 14 trials, randomizing a total of 8033 women. The unstratified analysis found early intervention with amniotomy and oxytocin to be associated with a modest reduction in the risk of caesarean section; however, the confidence interval (CI) included the null effect (risk ratio (RR) 0.89; 95% CI 0.79 to 1.01; 14 trials; 8033 women). In prevention trials, early augmentation was associated with a modest reduction in the number of caesarean births (RR 0.87; 95% CI 0.77 to 0.99; 11 trials; 7753). A policy of early amniotomy and early oxytocin was associated with a shortened duration of labour (average mean difference (MD) - 1.28 hours; 95% CI -1.97 to -0.59; eight trials; 4816 women). Sensitivity analyses excluding four trials with a full package of active management did not substantially affect the point estimate for risk of caesarean section (RR 0.87; 95% CI 0.73 to 1.05; 10 trials; 5165 women). We found no other significant effects for the other indicators of maternal or neonatal morbidity. In prevention trials, early intervention with amniotomy and oxytocin appears to be associated with a modest reduction in the rate of caesarean section over standard care.

Carmant L.,University of Montreal
Acta neurologica Scandinavica. Supplementum | Year: 2011

Infantile spasms (IS) are a unique and severe form of epilepsy associated with poor neurologic and developmental outcomes. The refractory spasms and abnormal electroencephalogram (EEG) patterns associated with the condition are believed to have a progressively detrimental impact. Therefore, rapid and complete control of spasms is the primary goal of treatment. Well-controlled clinical trials in Europe, Canada, and the United States have demonstrated that vigabatrin is efficacious and generally well-tolerated as monotherapy for IS. Several key studies, including pivotal trials that led to United States approval of vigabatrin in 2009, as well as comparative trials of vigabatrin and hormonal treatment, are the focus of this review. All studies assessed spasm cessation - usually as the primary endpoint - and adverse events. Vigabatrin dosages generally ranging from 100 to 150 mg/kg/day demonstrated efficacy to decrease or eradicate spasms and eliminate hypsarrhythmic EEG in patients with newly diagnosed IS. Several studies demonstrated long-term sustainability of spasm freedom with no negative impact on developmental outcomes. Vigabatrin was generally well-tolerated with few severe adverse events. Visual field defects cannot be adequately assessed in infants and young children, so this potential adverse effect was not evaluated in children with spasms. Notably, the time to response with vigabatrin was very rapid, generally occurring within 2 weeks of initial treatment. This allows for early treatment modification as needed. For infants who respond well to vigabatrin, treatment duration up to 6 months appears to be appropriate for realizing spasm freedom while limiting potential risks of adverse events and recurrences. © 2011 John Wiley & Sons A/S.

Fakhoury M.,University of Montreal
International Journal of Developmental Neuroscience | Year: 2015

Autism spectrum disorder (ASD) is a set of neurodevelopmental disorders that is among the most severe in terms of prevalence, morbidity and impact to the society. It is characterized by complex behavioral phenotype and deficits in both social and cognitive functions. Although the exact cause of ASD is still not known, the main findings emphasize the role of genetic and environmental factors in the development of autistic behavior. Environmental factors are also likely to interact with the genetic profile and cause aberrant changes in brain growth, neuronal development, and functional connectivity. The past few years have seen an increase in the prevalence of ASD, as a result of enhanced clinical tests and diagnostic tools. Despite growing evidence for the involvement of endogenous biomarkers in the pathophysiology of ASD, early detection of this disorder remains a big challenge. This paper describes the main behavioral and cognitive features of ASD, as well as the symptoms that differentiate autism from other developmental disorders. An attempt will be made to integrate all the available evidence which point to reduced brain connectivity, mirror neurons deficits, and inhibition-excitation imbalance in individuals with ASD. Finally, this review discusses the main factors involved in the pathophysiology of ASD, and illustrates some of the most important markers used for the diagnosis of this debilitating disorder. © 2015 Elsevier Ltd.

Rath S.,Universitaetsstrasse 5 9 | Rath S.,University of Montreal | Gutjahr W.J.,Universitaetsstrasse 5 9
Computers and Operations Research | Year: 2014

We consider a problem faced by international aid organizations after the occurrence of a natural disaster. A supply system with intermediate warehouses has to be established to provide affected people with relief goods. A three-objective optimization model with a medium-term economic, a short-term economic, and a humanitarian objective function is used. We apply the epsilon constraint method to determine the Pareto frontier. To solve the single-objective constrained optimization problem, we propose an exact solution method as well as a "math-heuristic" technique building on a MILP formulation with a heuristically generated constraint pool. As a subproblem, the multiple-depot, multiple-trip capacitated team orienteering problem is solved. We present a MIP formulation and a VNS procedure for this problem. Synthetically generated instances and a real-world illustration case are used for our computational studies. The results of the math-heuristic technique are compared to those obtained from an application of the NSGA-II metaheuristic and, where possible, to those of the exact solution approach. © 2011 Elsevier Ltd.

Bichet D.G.,University of Montreal
Kidney International | Year: 2012

A nephrogenic defect in urine concentration is well established in patients with polycystic kidney disease, but Ho et al. report a defect in the increase of plasma vasopressin in response to dehydration. On a cellular level, transient receptor potential channels responsible for osmoperception could interact with TRPPs encoded by the polycystic genes PKD1 and PKD2. © 2012 International Society of Nephrology.

Augustyniak M.,University of Montreal
Computational Statistics and Data Analysis | Year: 2014

The Markov-switching GARCH model offers rich dynamics to model financial data. Estimating this path dependent model is a challenging task because exact computation of the likelihood is infeasible in practice. This difficulty led to estimation procedures either based on a simplification of the model or not dependent on the likelihood. There is no method available to obtain the maximum likelihood estimator without resorting to a modification of the model. A novel approach is developed based on both the Monte Carlo expectation-maximization algorithm and importance sampling to calculate the maximum likelihood estimator and asymptotic variance-covariance matrix of the Markov-switching GARCH model. Practical implementation of the proposed algorithm is discussed and its effectiveness is demonstrated in simulation and empirical studies. © 2013 Elsevier B.V. All rights reserved.

Ridde V.,Unite de sante internationale | Ridde V.,University of Montreal | Ridde V.,Institute Of Recherche En Science Of La Sante Du Cnrst | Morestin F.,Unite de sante internationale
Health Policy and Planning | Year: 2011

In Africa, user fees constitute a financial barrier to access to health services. Increasingly, international aid agencies are supporting countries that abolish such fees. However, African decision-makers want to know if eliminating payment for services is effective and how it can be implemented. For this reason, given the increase in experiences and the repeated requests from decision-makers for current knowledge on this subject, we surveyed the literature. Using the scoping study method, 20 studies were selected and analysed. This survey shows that abolition of user fees had generally positive effects on the utilization of services, but at the same time, it highlights the importance of implementation processes and our considerable lack of knowledge on the matter at this time. We draw lessons from these experiences and suggest avenues for future research. © The Author 2010; all rights reserved.

Hybrid models combine multiple modelling approaches to represent complex, integrated systems of human and biophysical components. These models are highly data driven, and serve to aid in pattern extraction and knowledge synthesis, providing an important link between data sources and decision support. By allowing the simulation of the many emergent plausible futures for complex systems, hybrid models will become increasingly important decision-support tools. © 2010 Elsevier B.V.

Bockenhauer D.,University College London | Bichet D.G.,University of Montreal
Nature Reviews Nephrology | Year: 2015

Healthy kidneys maintain fluid and electrolyte homoeostasis by adjusting urine volume and composition according to physiological needs. The final urine composition is determined in the last tubular segment: the collecting duct. Water permeability in the collecting duct is regulated by arginine vasopressin (AVP). Secretion of AVP from the neurohypophysis is regulated by a complex signalling network that involves osmosensors, barosensors and volume sensors. AVP facilitates aquaporin (AQP)-mediated water reabsorption via activation of the vasopressin V2 receptor (AVPR2) in the collecting duct, thus enabling concentration of urine. In nephrogenic diabetes insipidus (NDI), inability of the kidneys to respond to AVP results in functional AQP deficiency. Consequently, affected patients have constant diuresis, resulting in large volumes of dilute urine. Primary forms of NDI result from mutations in the genes that encode the key proteins AVPR2 and AQP2, whereas secondary forms are associated with biochemical abnormalities, obstructive uropathy or the use of certain medications, particularly lithium. Treatment of the disease is informed by identification of the underlying cause. Here we review the clinical aspects and diagnosis of NDI, the various aetiologies, current treatment options and potential future developments. © 2015 Macmillan Publishers Limited.

The author's reflections on knowledge transfer/translation highlight the importance of the circular process between science and practice knowledge, leading to the notion of "knowledge exchange." She addresses the dilemmas of translating knowledge into clinical practice by describing her academic contributions to knowledge exchange within Family Systems Nursing (FSN). Teaching and research strategies are offered that address the circularity between science and practice knowledge. The evolution of 20 years of teaching, research, and clinical experience has resulted in the recent creation of a Center of Excellence in Family Nursing at the University of Montreal. The three main objectives of the Center uniquely focus on knowledge exchange by providing (a) a training context for skill development for nurses specializing in FSN, (b) a research milieu for knowledge "creation" and knowledge "in action" studies to further advance the practice of FSN, and (c) a family healing setting to support families who experience difficulty coping with health issues. © The Author(s) 2010.

Klein R.,Max Planck Institute of Neurobiology | Klein R.,Synergy Systems | Kania A.,Institute Of Recherches Cliniques Of Montreal Ircm | Kania A.,University of Montreal | Kania A.,McGill University
Current Opinion in Neurobiology | Year: 2014

Ephrin ligands and their Eph receptors hold our attention since their link to axon guidance almost twenty years ago. Since then, they have been shown to be critical for short distance cell-cell interactions in the nervous system. The interest in their function has not abated, leading to ever-more sophisticated studies generating as many surprising answers about their function as new questions. We discuss recent insights into their functions in the developing nervous system, including neuronal progenitor sorting, stochastic cell migration, guidance of neuronal growth cones, topographic map formation, as well as synaptic plasticity. © 2014 Elsevier Ltd.

Bockenhauer D.,University College London | Bichet D.G.,University of Montreal
Pediatric Nephrology | Year: 2014

Nephrogenic diabetes insipidus (NDI) provides an excellent model for the benefits and insights that can be gained from studying rare diseases. The discovery of underlying genes identified key molecules involved in urinary concentration, including the type 2 vasopressin receptor AVPR2 and the water channel AQP2, which constitute obvious pharmacologic targets. Subsequently developed drugs targeting AVPR2 not only provide potential benefit to some patients with NDI, but are now used for much more common clinical applications as diverse as nocturnal enuresis and heart failure. Yet, the story is still evolving: clinical observations and animal experiments continue to discover new ways to affect urinary concentration. These novel pathways can potentially be exploited for therapeutic gain. Here we review the (patho)physiology of water homoeostasis, the current status of clinical management, and potential new treatments. © 2013 IPNA.

Tarchini B.,Institute Of Recherches Cliniques Of Montreal Ircm | Jolicoeur C.,Institute Of Recherches Cliniques Of Montreal Ircm | Cayouette M.,Institute Of Recherches Cliniques Of Montreal Ircm | Cayouette M.,University of Montreal | Cayouette M.,McGill University
Developmental Cell | Year: 2013

Sound perception relies on the planar polarization of the mechanosensory hair cell apex, which develops aV-shaped stereocilia bundle pointing toward an eccentric kinocilium. It remains unknown how intrinsically asymmetric bundles arise and are concomitantly oriented in the tissue. We report here that mInsc, LGN, and Gαi proteins, which classically regulate mitotic spindle orientation, are polarized in a lateral microvilli-free region, or "bare zone," at the apical hair cell surface. By creating and extending the bare zone, these proteins trigger a relocalization of the eccentric kinocilium midway toward the cell center. aPKC is restrained medially by mInsc/LGN/Gαi, resulting in compartmentalization of the apical surface that imparts the V-shaped distribution of stereocilia and brings the asymmetric bundle in register with the relocalized kinocilium. Gαi is additionally required for lateral orientation of cochlear hair cells, providing a possible mechanism to couple the emergence of asymmetric stereocilia bundles with planar cell polarity. © 2013 Elsevier Inc.

Winship L.J.,Hampshire College | Obermeyer G.,University of Salzburg | Geitmann A.,University of Montreal | Hepler P.K.,University of Massachusetts Amherst
Trends in Plant Science | Year: 2011

The primary goal of our previous opinion paper (Winship, L.J. et al. (2010) Trends Plant Sci. 15, 363-369) [1] was to put two models for the control of pollen tube growth on the same theoretical and biophysical footing, and to then test both for consistency with basic principles and with experimental data. Our central thesis, then and now, is that the biophysical and biochemical mechanisms that enable pollen tubes to grow and to respond to their environment evolved in a physical context constrained by known, inescapable principles. First, pressure is a scalar, not a vector quantity. Second, the water movement in and out of plant cells that generates pressure is passive, not active, and is controlled by differences in water potential. Here we respond to the issues raised by Zonia and Munnik (Trends Plant Sci. 2011; this issue) [2] in the light of new evidence concerning turgor pressure and pollen tube growth rates. © 2011 Elsevier Ltd.

Touchette D.,University of Montreal
Proceedings of the Annual ACM Symposium on Theory of Computing | Year: 2015

We define a new notion of information cost for quantum protocols, and a corresponding notion of quantum information complexity for bipartite quantum tasks. These are the fully quantum generalizations of the analogous quantities for bipartite classical tasks that have found many applications recently, in particular for proving communication complexity lower bounds and direct sum theorems. Finding such a quantum generalization of information complexity was one of the open problems recently raised by Braver-man (STOC'12). Previous attempts have been made to define such a quantity for quantum protocols, with particular applications in mind; our notion differs from these in many respects. First, it directly provides a lower bound on the quantum communication cost, independent of the number of rounds of the underlying protocol. Secondly, we provide an operational interpretation for quantum information complexity: we show that it is exactly equal to the amortized quantum communication complexity of a bipartite task on a given input. This generalizes a result of Braverman and Rao (FOCS'11) to quantum protocols. Along the way to prove this result, we even strengthens the classical result in a bounded round scenario, and also prove important structural properties of quantum information cost and complexity. We prove that using this definition leads to the first general direct sum theorem for bounded round quantum communication complexity. Previous direct sum results in quantum communication complexity either held for some particular classes of functions, or were general but only held for single-round protocols. We also discuss potential applications of the new quantities to obtain lower bounds on quantum communication complexity.

Zhang Z.,Carleton University | Liu J.,Carleton University | Gu J.,Carleton University | Su L.,Massachusetts Institute of Technology | Cheng L.,University of Montreal
Energy and Environmental Science | Year: 2014

Polymer electrolyte fuel cells (PEFCs) are promising power sources in portable and transportation applications because of their high energy densities, low operating temperatures and ease of transportation and storage. However, high cost, low activity and short durability of electrocatalysts are restricting the commercialization of PEFCs. Metal oxides have abundant sources, low cost, high chemical and electrochemical stability, abundant hydroxyl groups on their surfaces, and strong interactions with metal nanoparticles, and thus are promising to reduce the current problems of PEFCs. In this review, binary metal oxides such as titanium oxide, tungsten oxide, molybdenum oxide, ruthenium oxide, tin oxide, cerium oxide and manganese oxide, and multi-component perovskite oxides are chosen based on the selection criteria of metal oxides and introduced as independent electrocatalysts, co-catalysts and supports for various anode oxidation and cathode reduction reactions in PEFCs. The effects of composition, morphology, doping and mixing of metal oxides on their electrocatalytic performance in PEFCs have also been summarized. Finally, several of the most promising metal oxides and possible research trends of metal oxides are recommended for future PEFCs. This journal is © the Partner Organisations 2014.

Fakhoury M.,University of Montreal
Journal of Psychiatric Research | Year: 2016

Schizophrenia is a mental disorder that affects close to 1% of the population. Individuals with this disorder often present signs such as hallucination, anxiety, reduced attention, and social withdrawal. Although antipsychotic drugs remain the cornerstone of schizophrenia treatment, they are associated with severe side effects. Recently, the endocannabinoid system (ECS) has emerged as a potential therapeutic target for pharmacotherapy that is involved in a wide range of disorders, including schizophrenia. Since its discovery, a lot of effort has been devoted to the study of compounds that can modulate its activity for therapeutic purposes. Among them, cannabidiol (CBD), a non-psychoactive component of cannabis, shows great promise for the treatment of psychosis, and is associated with fewer extrapyramidal side effects than conventional antipsychotic drugs. The overarching goal of this review is to provide current available knowledge on the role of the dopamine system and the ECS in schizophrenia, and to discuss key findings from animal studies and clinical trials investigating the antipsychotic potential of CBD. © 2016 Published by Elsevier Ltd.

Trudel J.G.,University of Toronto | Leduc N.,University of Montreal | Dumont S.,Laval University
Psycho-Oncology | Year: 2014

Objective Communication between cancer patients and healthcare providers is recognized as an important aspect of these patients' health-related quality of life (HRQOL). Nevertheless, no study has examined whether perceived communication between physicians and breast cancer patients is a determining factor in their HRQOL along the disease's trajectory. This longitudinal study aimed to ascertain whether such communication influenced the HRQOL of such women at three points in time. Methods The sample consisted of 120 French-speaking women with stage I or II breast cancer aged 18years or over (mean=55years) who underwent a lumpectomy with adjuvant treatment. The women filled out questionnaires at three different times: around the time of diagnosis, halfway through radiotherapy and at follow-up. Either at the hospital or at home, they completed demographic and medical data questionnaires, the Medical Outcomes Study-Social Support Survey, an HRQOL questionnaire (EORTC QLQ-C30/BR23) and the Medical Communication Competence Scale. Results Generalized estimated equations analyses indicated that the women's perceptions of their own communication skills towards physicians had a greater impact on their HRQOL than the women's perception of physicians' communication skills. The women had better global health and better role, emotional, cognitive and sexual functioning as well as fewer side effects and symptoms during radiotherapy and at follow-up when they perceived themselves as competent communicators at diagnosis and during radiotherapy. Conclusions The results underscore the importance for breast cancer patients of being proactive in information seeking and in the socio-emotional aspect of their relationship with physicians to enhance their HRQOL. Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd.

Therien J.-P.,University of Montreal
Global Policy | Year: 2012

Building on the work of the United Nations Intellectual History Project, this article argues that the ideology of human development has now become the driving normative force behind the global policies supported by the UN in the area of development. The first part focuses on the UN's official discourse of the past two decades, and shows how it has been influenced by the concept of human development. The second section examines a set of global policies that illustrate how the UN has sought to put the principles of human development into practice. The article concludes that while human development ideology has represented for twenty years the most credible critique of mainstream development policies, its impact - like that of the UN in world affairs - remains nonetheless limited. © 2012 London School of Economics and Political Science and John Wiley & Sons Ltd.

Hallenbeck P.C.,University of Montreal
Biofuels | Year: 2011

Hydrogen technologies are under intense research and development at present, to enable their future use as a fuel, in particular for the transportation sector. Whilst the engineering of hydrogen storage and use is relatively well developed, with prototype cars already on the road, a viable, sustainable means of renewable hydrogen production is lacking. A number of options for the biological production of hydrogen from abundantly available substrates - water, waste streams and, potentially, lignocellulosic materials - are available. Thus, solar energy can either be directly converted to hydrogen in some scenarios, or fixed carbon compounds generated through conventional photosynthesis can subsequently be converted to hydrogen in others. Much is already known about the underlying biological principles, but each microbial path to hydrogen production presents technical barriers to realization on a practical scale. Here, the key limiting factors in each approach are highlighted and future perspectives for biological hydrogen production are discussed. © 2011 Future Science Ltd.

Leblond J.,University of Montreal | Petitjean A.,Queens University
ChemPhysChem | Year: 2011

Taken to the molecular level, the concept of "tweezers" opens a rich and fascinating field at the convergence of molecular recognition, biomimetic chemistry and nanomachines. Composed of a spacer bridging two interaction sites, the behaviour of molecular tweezers is strongly influenced by the flexibility of their spacer. Operating through an "induced-fit" recognition mechanism, flexible molecular tweezers select the conformation(s) most appropriate for substrate binding. Their adaptability allows them to be used in a variety of binding modes and they have found applications in chirality signalling. Rigid spacers, on the contrary, display a limited number of binding states, which lead to selective and strong substrate binding following a "lock and key" model. Exquisite selectivity may be expressed with substrates as varied as C 60, nanotubes and natural cofactors, and applications to molecular electronics and enzyme inhibition are emerging. At the crossroad between flexible and rigid spacers, stimulus-responsive molecular tweezers controlled by ionic, redox or light triggers belong to the realm of molecular machines, and, applied to molecular tweezing, open doors to the selective binding, transport and release of their cargo. Applications to controlled drug delivery are already appearing. The past 30 years have seen the birth of molecular tweezers; the next many years to come will surely see them blooming in exciting applications. Feeling the pinch: Aimed at controlled substrate binding, molecular tweezers have been engineered to offer a range of flexibility degrees and a variety of interaction sites for substrate binding (see picture). Applications ranging from molecular recognition, molecular electronics and enzyme inhibition to the assembly of complex topological systems and drug carriers are emerging, and show the promise of this very rich field. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mignotte M.,University of Montreal
Pattern Analysis and Applications | Year: 2014

In this paper, we address the problem of estimating a segmentation map into regions from a soft (or possibly probabilistic) boundary representation. For this purpose, we have defined a simple non-stationary MRF model with long-range pairwise interactions whose potentials are estimated from the likelihood of the presence of an edge at each considered pair of pixels. Another contribution of this paper is also to demonstrate that an efficient and interesting alternative strategy to complex and elaborate region-based segmentation models consists in averaging several (quickly estimated) soft contour maps (obtained, for example, with simpler edge-based segmentation models) and to use this MRF reconstruction model to achieve a reliable and accurate segmentation map into regions. This model has been successfully applied on the Berkeley image database. The experiments reported in this paper demonstrate that the proposed segmentation model from an edge map is reliable and that this segmentation strategy is efficient (in terms of visual evaluation and quantitative performance measures) and performs well compared with the best existing state-of-the-art segmentation methods recently proposed in the literature. © 2012 Springer-Verlag London Limited.

Schneiderman M.,McGill University | Balayla J.,University of Montreal
Journal of Maternal-Fetal and Neonatal Medicine | Year: 2013

Objective: Currently, no ACOG guidelines address the issue of the optimal timing of delivery in placenta previa. Though there is an increased risk of neonatal morbidity and mortality when electively delivered preterm, it is unclear whether adverse neonatal outcomes exist when these pregnancies make it beyond term. By comparing neonatal outcomes amongst pregnancies with placenta previa versus those from cesarean for another indication at term, the objective of this study was to determine whether placenta previa is an independent risk factor for adverse neonatal outcomes at term. Methods: We conducted a population-based cohort-study using the CDC's Linked Birth-Infant Death data from the United States. The effect of placenta previa on the risk of adverse neonatal outcomes was estimated using unconditional logistic regression analysis, adjusting for relevant confounders. Results: Our cohort consisted of 3550842 deliveries meeting inclusion criteria. The incidence of placenta previa at term was 1.3/1000 (n=4,492), accounting for 40.6% of all previa cases. Relative to cesareans for other indications, pregnancies with placenta previa had an increased risk of IUGR 3.20 [2.50-4.10], SGA 2.70 [2.45-2.97], respiratory distress 3.82 [2.91-5.00], prolonged ventilation 3.41 [2.70-4.32] and neonatal anemia 6.87 [4.43-10.65]. Rates of meconium aspiration syndrome, seizures, birth injury and overall infant mortality do not appear to be affected by this condition. Conclusion: Relative to cesareans for other indications, placenta previa is associated with increased morbidity, but not mortality, at term. This information might be helpful in the development of future guidelines, which are currently needed to guide and standardize clinical practice regarding the optimal timing of delivery in placenta previa. © 2013 Informa UK Ltd.

Mignotte M.,University of Montreal
IEEE Transactions on Geoscience and Remote Sensing | Year: 2010

In this paper, we present a nonstationary Markov random field (MRF) fusion model for the color display of hyperspectral images. The proposed fusion or dimensionality reduction model is derived from the preservation of spectral distance criterion. This quantitative metric of good dimensionality reduction and meaningful visualization allows us to derive an appealing fusion model of high-dimensional spectral data, expressed as a Gibbs distribution or a nonstationary MRF model defined on a complete graph. In this framework, we propose a computationally efficient coarse-to-fine conjugate-gradient optimization method to minimize the cost function related to this energy-based fusion model. The experiments reported in this paper demonstrate that the proposed visualization method is efficient (in terms of preservation of spectral distances and discriminality of pixels with different spectral signatures) and performs well compared to the best existing state-of-the-art multidimensional imagery color display methods recently proposed in the literature. © 2010 IEEE.

Ernzerhof M.,University of Montreal
Journal of Chemical Physics | Year: 2011

Theories of molecular electronic devices (MEDs) are quite involved in general. However, various prominent features of MEDs can be understood drawing only on elementary quantum theory. To support this point of view, we provide a two component orbital theory that enables one to reproduce various important features of MEDs. In this theory, the device orbitals are divided into two components, each of which is obtained from simple rules. To illustrate our two-component model, we apply it to explain, among other things, the conductance suppression in cross-conjugated systems and the dependence of the conductance on the contact position in aromatic systems. © 2011 American Institute of Physics.

Telford M.J.,University College London | Budd G.E.,Uppsala University | Philippe H.,French National Center for Scientific Research | Philippe H.,University of Montreal
Current Biology | Year: 2015

Animals make up only a small fraction of the eukaryotic tree of life, yet, from our vantage point as members of the animal kingdom, the evolution of the bewildering diversity of animal forms is endlessly fascinating. In the century following the publication of Darwin's Origin of Species, hypotheses regarding the evolution of the major branches of the animal kingdom - their relationships to each other and the evolution of their body plans - was based on a consideration of the morphological and developmental characteristics of the different animal groups. This morphology-based approach had many successes but important aspects of the evolutionary tree remained disputed. In the past three decades, molecular data, most obviously primary sequences of DNA and proteins, have provided an estimate of animal phylogeny largely independent of the morphological evolution we would ultimately like to understand. The molecular tree that has evolved over the past three decades has drastically altered our view of animal phylogeny and many aspects of the tree are no longer contentious. The focus of molecular studies on relationships between animal groups means, however, that the discipline has become somewhat divorced from the underlying biology and from the morphological characteristics whose evolution we aim to understand. Here, we consider what we currently know of animal phylogeny; what aspects we are still uncertain about and what our improved understanding of animal phylogeny can tell us about the evolution of the great diversity of animal life. © 2015 Elsevier Ltd All rights reserved.

Audet M.,University of Montreal
Cell | Year: 2012

G-protein-coupled receptors serve as key signal transduction conduits, linking extracellular inputs with diverse cellular responses. These receptors eluded structural characterization for decades following their identification. A landmark structure of rhodopsin provided a basis for structure-function studies and homology modeling, but advances in receptor biology suffered from a lack of receptor-specific structural insights. The recent explosion in GPCR structures confirms some features predicted by rhodopsin-based models, and more importantly, it reveals unexpected ligand-binding modes and critical aspects of the receptor activation process. The new structures also promise to foster studies testing emerging models for GPCR function such as receptor dimerization and ligand-biased signaling. Copyright © 2012 Elsevier Inc. All rights reserved.

Joly S.,University of Montreal
Molecular Ecology Resources | Year: 2012

I introduce the software jml that tests for the presence of hybridization in multispecies sequence data sets by posterior predictive checking following Joly, McLenachan and Lockhart (2009, American Naturalist e54). Although their method could potentially be applied on any data set, the lack of appropriate software made its application difficult. The software jml thus fills a need for an easy application of the method but also includes improvements such as the possibility to incorporate uncertainty in the species tree topology. The jml software uses a posterior distribution of species trees, population sizes and branch lengths to simulate replicate sequence data sets using the coalescent with no migration. A test quantity, defined as the minimum pairwise sequence distance between sequences of two species, is then evaluated on the simulated data sets and compared to the one estimated from the original data. Because the test quantity is a good predictor of hybridization events, departure from the bifurcating species tree model could be interpreted as evidence of hybridization. Software performance in terms of computing time is evaluated for several parameters. I also show an application example of the software for detecting hybridization among native diploid North American roses. © 2011 Blackwell Publishing Ltd.

Westberg K.-G.,Umea University | Kolta A.,University of Montreal
International Review of Neurobiology | Year: 2011

Mastication is a vital function that ensures that ingested food is broken down into pieces and prepared for digestion. This review outlines the masticatory behavior in terms of the muscle activation patterns and jaw movements and gives an overview of the organization and function of the trigeminal neuronal circuits that are known to take part in the generation and control of oro-facial motor functions. The basic pattern of rhythmic jaw movements produced during mastication is generated by a Central Pattern Generator (CPG) located in the pons and medulla. Neurons within the CPG have intrinsic properties that produce a rhythmic activity, but the output of these neurons is modified by inputs that descend from the higher centers of the brain, and by feedback from sensory receptors, in order to constantly adapt the movement to the food properties. © 2011 Elsevier Inc.

Purpose: Whenever possible, neuraxial anesthesia is the preferred technique for Cesarean delivery; however, under certain circumstances, general anesthesia remains the most appropriate choice. The purpose of this Continuing Professional Development module is to review the key issues regarding general anesthesia for Cesarean delivery. Principal findings: In developed countries, anesthesia-related maternal mortality and morbidity are both low. Mortality following Cesarean delivery under general anesthesia is attributable chiefly to failed intubation or other induction-related issues. Extubation can also be a danger period. The various methods of preventing difficult intubation and the associated consequences include airway assessment, fasting during obstetric labour, and pharmacological prophylaxis for aspiration. The traditional rapid sequence induction has been slightly modified because of the increased use of propofol and remifentanil. Difficult airway management algorithms specific to the pregnant woman are being developed and tend to recommend the use of supraglottic devices for unanticipated difficult intubation. The prevention of intraoperative awareness is another major consideration. Maintenance with halogenated agents at > 0.7 minimum alveolar concentration (MAC) is recommended; however, propofol maintenance can be an interesting option when uterine atony is present. Multimodal postoperative analgesia is recommended. Conclusion: A general anesthetic for Cesarean delivery should be based on the following principles: preventing aspiration, anticipating a difficult intubation, maintaining oxygenation, insuring materno-feto-placental perfusion and maintaining a deep level of anesthesia to avoid intraoperative awareness while minimizing neonatal effects. © 2014 Canadian Anesthesiologists' Society.

Badjagbo K.,University of Montreal
Clinical Chemistry and Laboratory Medicine | Year: 2012

Volatile biomarker analysis in exhaled breath is becoming one of the desirable strategies for cancer detection because it may offer a relatively inexpensive, rapid, and non-invasive screening method for early diagnosis. Breath analysis has attracted a considerable amount of scientific and clinical interest over the past decade. However, breath is not yet used for routine medical diagnostic purposes. Challenges faced in the development of breath analysis for cancer diagnosis include developing techniques that can measure biomarkers in exhaled breath at ultratrace levels, providing definitive evidence for their presence and for the relationship between the proposed biomarker and the underlying condition. Various analytical methods are used for the detection of breath biomarkers. Gas chromatography-based methods which involve sample collection, analyte preconcentration, desorption, and separation steps are the most popular. However, direct-sampling mass spectrometry techniques have been proven more reliable for air analysis without prior sample pretreatment or chromatographic separation. This review focuses on the most commonly used direct mass spectrometry methods for the direct online analysis of endogenous cancer biomarkers in exhaled breath, with particular attention to principle of detection, method performance, advantages, shortcomings, recent advances, and applications within health-related studies for cancer biomarkers research. The principle behind the science of breath analysis for cancer diagnosis is also discussed. © 2012 by Walter de Gruyter Berlin Boston.

Frohlich K.L.,University of Montreal | Abel T.,University of Bern
Sociology of Health and Illness | Year: 2014

While empirical evidence continues to show that people living in low socio-economic status neighbourhoods are less likely to engage in health-enhancing behaviour, our understanding of why this is so remains less than clear. We suggest that two changes could take place to move from description to understanding in this field; (i) a move away from the established concept of individual health behaviour to a contextualised understanding of health practices; and (ii) a switch from focusing on health inequalities in outcomes to health inequities in conditions. We apply Pierre Bourdieu's theory on capital interaction but find it insufficient with regard to the role of agency for structural change. We therefore introduce Amartya Sen's capability approach as a useful link between capital interaction theory and action to reduce social inequities in health-related practices. Sen's capability theory also elucidates the importance of discussing unequal chances in terms of inequity, rather than inequality, in order to underscore the moral nature of inequalities. We draw on the discussion in social geography on environmental injustice, which also underscores the moral nature of the spatial distribution of opportunities. The article ends by applying this approach to the 'Interdisciplinary study of inequalities in smoking' framework. © 2013 Foundation for the Sociology of Health & Illness/John Wiley & Sons Ltd.

Cornely O.A.,University of Cologne | Crook D.W.,Microbiology and Infectious Diseases | Esposito R.,Clinica delle Malattie Infettive e Tropicali | Poirier A.,Center Hospitalier Regional Of Trois Rivieres | And 5 more authors.
The Lancet Infectious Diseases | Year: 2012

Background: Infection with Clostridium difficile is the primary infective cause of antibiotic-associated diarrhoea. We aimed to compare efficacy and safety of fidaxomicin and vancomycin to treat patients with C difficile infection in Europe, Canada, and the USA. Methods: In this multicentre, double-blind, randomised, non-inferiority trial, we enrolled patients from 45 sites in Europe and 41 sites in the USA and Canada between April 19, 2007, and Dec 11, 2009. Eligible patients were aged 16 years or older with acute, toxin-positive C difficile infection. Patients were randomly allocated (1:1) to receive oral fidaxomicin (200 mg every 12 h) or oral vancomycin (125 mg every 6 h) for 10 days. The primary endpoint was clinical cure, defined as resolution of diarrhoea and no further need for treatment. An interactive voice-response system and computer-generated randomisation schedule gave a randomisation number and medication kit number for each patient. Participants and investigators were masked to treatment allocation. Non-inferiority was prespecified with a margin of 10%. Modified intention-to-treat and per-protocol populations were analysed. This study is registered with ClinicalTrials.gov, number NCT00468728. Findings: Of 535 patients enrolled, 270 were assigned fidaxomicin and 265 vancomycin. After 26 patients were excluded, 509 were included in the modified intention-to-treat (mITT) population. 198 (91·7%) of 216 patients in the per-protocol population given fidaxomicin achieved clinical cure, compared with 213 (90·6%) of 235 given vancomycin, meeting the criterion for non-inferiority (one-sided 97·5% CI -4·3%). Non-inferiority was also shown for clinical cure in the mITT population, with 221 (87·7%) of 252 patients given fidaxomicin and 223 (86·8%) of 257 given vancomycin cured (one-sided 97·5% CI -4·9%). In most subgroup analyses of the primary endpoint in the mITT population, outcomes in the two treatment groups did not differ significantly; although patients receiving concomitant antibiotics for other infections had a higher cure rate with fidaxomicin (46 [90·2%] of 51) than with vancomycin (33 [73·3%] of 45; p=0·031). Occurrence of treatment-emergent adverse events did not differ between groups. 20 (7·6%) of 264 patients given at least one dose of fidaxomicin and 17 (6·5%) of 260 given vancomycin died. Interpretation: Fidaxomicin could be an alternative treatment for infection with C difficile, with similar efficacy and safety to vancomycin. Funding: Optimer Pharmaceuticals. © 2012 Elsevier Ltd.

Lortie A.,University of Montreal
Handbook of Clinical Neurology | Year: 2013

Psychogenic nonepileptic seizures (PNES) are clinical events resembling epileptic seizures but lacking abnormal cortical electrical discharges. They are involuntary manifestations of a psychological distress. PNES are less frequent in the pediatric population than in adults, they represent from 3.5 to 9% of patients admitted for prolonged video-EEG (PV-EEG). Diagnosis is rarely made on history only and PV-EEG is mandatory to obtain a definitive diagnosis. Children as young as 5 years can present with PNES. They are more frequent in girls except in school age children where boys are identically or more represented than girls. PNES can either present with subtle signs, even unresponsiveness, or prominent motor activity. Major differential diagnosis is absences, day dreaming, and complex partial seizures including hyperkinetic frontal seizures. PNES are usually rapidly registered during PV-EEG and provocative methods have not been thoroughly studied in children. Major risk factors are psychological stressors, such as school or family problems. Psychiatric conditions are less frequent than in adults though they should be looked for. Prognosis is better than in adults, and most children become PNES-free. There are no guidelines for treatment, however stressors should be addressed. In general, it should be clearly explained that PNES are not epileptic seizures. © 2013 Elsevier B.V.

Lessard J.A.,University of Montreal | Crabtree G.R.,Stanford University
Annual Review of Cell and Developmental Biology | Year: 2010

Stem cells of all types are characterized by a stable, heritable state permissive of multiple developmental pathways. The past five years have seen remarkable advances in understanding these heritable states and the ways that they are initiated or terminated. Transcription factors that bind directly to DNA and have sufficiency roles have been most easy to investigate and, perhaps for this reason, are most solidly implicated in pluripotency. In addition, large complexes of ATP-dependent chromatin-remodeling and histone-modification enzymes that have specialized functions have also been implicated by genetic studies in initiating andor maintaining pluripotency or multipotency. Several of these ATP-dependent remodeling complexes play non-redundant roles, and the esBAF complex facilitates reprogramming of induced pluripotent stem cells. The recent finding that virtually all histone modifications can be rapidly reversed and are often highly dynamic has raised new questions about how histone modifications come to play a role in the steady state of pluripotency. Another surprise from genetic studies has been the frequency with which the global effects of mutations in chromatin regulators can be largely reversed by a single target gene. These genetic studies help define the arena for future mechanistic studies that might be helpful to harness pluripotency for therapeutic goals. Copyright © 2010 by Annual Reviews. All rights reserved.

Ferland G.,University of Montreal
BioFactors | Year: 2012

Historically discovered for its role in blood coagulation, there is now convincing evidence that vitamin K has important actions in the nervous system. As a unique cofactor to the γ-glutamyl carboxylase enzyme, vitamin K contributes to the biological activation of proteins Gas6 and protein S, ligands for the receptor tyrosine kinases of the TAM family (Tyro3, Axl, and Mer). Functionally, Gas6 has been involved in a wide range of cellular processes that include cell growth, survival, and apoptosis. In brain, vitamin K also participates in the synthesis of sphingolipids, an important class of lipids present in high concentrations in brain cell membranes. In addition to their structural role, sphingolipids are now known to partake in important cellular events such as proliferation, differentiation, senescence and cell-cell interactions. In recent years, studies have linked alterations in sphingolipid metabolism to age-related cognitive decline and neurodegenerative diseases such as Alzheimer's disease (AD). Emerging data also point to unique actions of the K vitamer menaquinone-4 (MK-4) against oxidative stress and inflammation. Finally, there is now data to suggest that vitamin K has the potential to influence psychomotor behavior and cognition. This review presents an overview of what is known of the role of vitamin K in brain function. © 2012 International Union of Biochemistry and Molecular Biology, Inc.

Bujold A.,University of Montreal | Craig T.,University of Toronto | Jaffray D.,University of Toronto | Dawson L.A.,University of Toronto
Seminars in Radiation Oncology | Year: 2012

Cancer control and toxicity outcomes are the mainstay of evidence-based medicine in radiation oncology. However, radiotherapy is an intricate therapy involving numerous processes that need to be executed appropriately in order for the therapy to be delivered successfully. The use of image-guided radiation therapy (IGRT), referring to imaging occurring in the radiation therapy room with per-patient adjustments, can increase the agreement between the planned and the actual dose delivered. However, the absence of direct evidence regarding the clinical benefit of IGRT has been a criticism. Here, we dissect the role of IGRT in the radiotherapy (RT) process and emphasize its role in improving the quality of the intervention. The literature is reviewed to collect evidence that supports that higher-quality dose delivery enabled by IGRT results in higher clinical control rates, reduced toxicity, and new treatment options for patients that previously were without viable options. © 2012.

Lacroix A.,University of Montreal
Journal of Clinical Endocrinology and Metabolism | Year: 2010

Adrenocortical cancer (ACC) is a rare and often aggressive malignancy that requires multidisciplinary expertise for optimal management. It can present with symptoms of rapidly appearing excess steroid secretion or an abdominal mass, or it can be discovered incidentally. Thorough imaging and endocrine evaluations can identify the majority of ACCs among stadrenal tumors; however, somesmaller ACCs are better identified using fluorodeoxyglucose-positron emission tomography/ computed tomography scan. Complete resection by an expert surgeon is the only potentially curative treatment for ACC, and tumor spillage should be avoided. Histopathology is important for diagnosis, but immunohistochemistry markersandgene profiling of the resected tumormaybecomesuperior to current staging systems to stratify prognosis. Despite complete resection in stage I-III tumors, approximately 40% of patients develop metastasis within 2 yr. Some retrospective studies indicate that adjuvant mitotane therapy prolongs disease-free survival, leading several centers to recommend its administration; prospective studies are under way to provide future evidence-based recommendations. For locally invading ACC, extensive en bloc resection is attempted, followed by adjuvant mitotane and, in selected cases, adjuvant radiotherapy. When ACC is not surgically resectable, mitotane therapy is adjusted to reach serum levels of 14-20 μg/ml. Careful replacement of glucocorticoid and mineralocorticoid deficiency after surgery or mitotane therapy is important; steroid excess from remaining tumor burden should also be controlled to avoid its morbidities. For metastatic disease, combination chemotherapy should be administered, if possible, in the context of multicenter collaborative research protocols. New insights in the molecular pathogenesis of ACC should allow the development of improved targeted therapies. Copyright © 2010 by The Endocrine Society.

Schiller P.W.,Clinical Research Institute of Montreal | Schiller P.W.,University of Montreal
Life Sciences | Year: 2010

Strategies for the design of bi- or multifunctional drugs are reviewed. A distinction is made between bifunctional drugs interacting in a monovalent fashion with two targets and ligands containing two distinct pharmacophores binding in a bivalent mode to the two binding sites in a receptor heterodimer. Arguments are presented to indicate that some of the so-called "bivalent" ligands reported in the literature are unlikely to simultaneously interact with two binding sites. Aspects related to the development of bi- or multifunctional drugs are illustrated with examples from the field of opioid analgesics. The drug-like properties of the tetrapeptide Dmt1[DALDA] with triple action as a μ opioid agonist, norepinephrine uptake inhibitor and releaser of endogenous opioid peptides to produce potent spinal analgesia are reviewed. Rationales for the development of opioid peptides with mixed agonist/antagonist profiles as analgesics with reduced side effects are presented. Progress in the development of mixed μ opioid agonist/δ opioid antagonists with low propensity to produce tolerance and physical dependence is reviewed. Efforts to develop bifunctional peptides containing a μ opioid agonist and a cholecystokinin antagonist or an NK1 receptor antagonist as analgesics expected to produce less tolerance and dependence are also reviewed. A strategy to improve the drug-like properties of bifunctional opioid peptide analgesics is presented. © 2009 Elsevier Inc.

Brodeur J.,University of Montreal
Evolutionary Applications | Year: 2012

Host/prey specificity is a significant concern in biological control. It influences the effectiveness of a natural enemy and the risks it might have on non-target organisms. Furthermore, narrow host specificity can be a limiting factor for the commercialization of natural enemies. Given the great diversity in taxonomy and mode of action of natural enemies, host specificity is a highly variable biological trait. This variability can be illustrated by opportunist fungi from the genus Lecanicillium, which have the capacity to exploit a wide range of hosts - from arthropod pests to fungi causing plant diseases - through different modes of action. Processes determining evolutionary trajectories in host specificity are closely linked to the modes of action of the natural enemy. This hypothesis is supported by advances in fungal genomics concerning the identity of genes and biological traits that are required for the evolution of life history strategies and host range. Despite the significance of specificity, we still need to develop a conceptual framework for better understanding of the relationship between specialization and successful biological control. The emergence of opportunistic pathogens and the development of 'omic' technologies offer new opportunities to investigate evolutionary principles and applications of the specificity of biocontrol agents. © 2012 Blackwell Publishing Ltd.

Tremblay R.E.,University College Dublin | Tremblay R.E.,University of Montreal | Tremblay R.E.,French Institute of Health and Medical Research
Journal of Child Psychology and Psychiatry and Allied Disciplines | Year: 2010

This paper reviews publications on developmental trajectories of disruptive behaviour (DB) problems (aggression, opposition-defiance, rule breaking, and stealing-vandalism) over the past decade. Prior to these studies two theoretical models had strongly influenced research on DB: social learning and disease onset. According to these developmental perspectives, children learn DB from their environment and onset of the disease is triggered by accumulated exposition to disruptive models in the environment, including the media. Most of the evidence came from studies of school age children and adolescents. Longitudinal studies tracing developmental trajectories of DB from early childhood onwards suggest an inversed developmental process. DB are universal during early childhood. With age, children learn socially acceptable behaviours from interactions with their environment. A 'disease' status is given to children who fail to learn the socially acceptable behaviours. The mechanisms that lead to deficits in using socially accepted behaviours are strongly intergenerational, based on complex genetic and environmental contributions, including epigenetic mechanisms. Prevention of these deficits requires early, intensive and long-term support to parents and child. Newly discovered epigenetic mechanisms suggest that intensive perinatal interventions will have impacts on numerous aspects of physical and mental health, including DB. This review also concludes that: a) subtypes of disruptive behaviours should not be aggregated because they have different developmental trajectories and require specific corrective interventions; b) the overt-covert and destructive- nondestructive dimensions appear the most useful to create DB subtypes; c) overt DB onset before covert DB because the latter require more brain maturation; d) DB subtype taxonomies are more useful for clinicians than developmental taxonomies because the latter are post mortem diagnoses and clinicians' retrospective information is unreliable; e) we need large-scale collaborative preventive experimental interventions starting during early pregnancy to advance knowledge on causes and prevention of DB problems. © 2010 The Author. Journal compilation © 2010 Association for Child and Adolescent Mental Health.

Borden K.L.B.,University of Montreal
Clinical and Investigative Medicine | Year: 2011

Identifying and targeting specific oncogenes, with the hope that the resultant therapies may eventually prove to exert positive clinical effects, is a major effort in the area of cancer therapeutics. The eukaryotic translation initiation factor, eIF4E, is overexpressed in many cancers, including acute myeloid leukemia. ?e role of eIF4E in oncogenic transformation and the development of a means to directly target its activity with ribavirin are discussed here. Results from early stage clinical trials and factors contributing to the development of clinical resistance to ribavirin are also described. © 2011 CIM.

Mignotte M.,University of Montreal
IEEE Transactions on Neural Networks | Year: 2011

In this paper, we present an efficient coarse-to-fine multiresolution framework for multidimensional scaling and demonstrate its performance on a large-scale nonlinear dimensionality reduction and embedding problem in a texture feature extraction step for the unsupervised image segmentation problem. We demonstrate both the efficiency of our multiresolution algorithm and its real interest to learn a nonlinear low-dimensional representation of the texture feature set of an image which can then subsequently be exploited in a simple clustering-based segmentation algorithm. The resulting segmentation procedure has been successfully applied on the Berkeley image database, demonstrating its efficiency compared to the best existing state-of-the-art segmentation methods recently proposed in the literature. © 2010 IEEE.

Mignotte M.,University of Montreal
Information Fusion | Year: 2014

This paper proposes a new and reliable segmentation approach based on a fusion framework for combining multiple region-based segmentation maps (with any number of regions) to provide a final improved (i.e., accurate and consistent) segmentation result. The core of this new combination model is based on a consensus (cost) function derived from the recent information Theory based variation of information criterion, proposed by Meila, and allowing to quantify the amount of information that is lost or gained in changing from one clustering to another. In this case, the resulting consensus energy-based segmentation fusion model can be efficiently optimized by exploiting an iterative steepest local energy descent strategy combined with a connectivity constraint. This new framework of segmentation combination, relying on the fusion of inaccurate, quickly and roughly calculated, spatial clustering results, emerges as an appealing alternative to the use of complex segmentation models existing nowadays. Experiments on the Berkeley Segmentation Dataset show that the proposed fusion framework compares favorably to previous techniques in terms of reliability scores. © 2013 Elsevier B.V. All rights reserved.

Marquette I.,University of Montreal
Journal of Physics A: Mathematical and Theoretical | Year: 2010

We present a method to obtain higher order integrals and polynomial algebras for two-dimensional quantum superintegrable systems separable in Cartesian coordinates from ladder operators. All systems with a second- and a third-order integral of motion separable in Cartesian coordinates were studied. The integrals of motion of two of them do not generate a cubic algebra. We construct for these Hamiltonians a higher order polynomial algebra from their ladder operators. We obtain quintic and seventh-order polynomial algebras. We also give for the polynomial algebras of order 7 realizations in terms of deformed oscillator algebras. These realizations and finite-dimensional unitary representations allow us to obtain the energy spectrum. We also apply the construction to the caged anisotropic harmonic oscillator and a system involving the fourth Painlevé transcendent. © 2010 IOP Publishing Ltd.

Hanessian S.,University of Montreal
Natural Products in Medicinal Chemistry | Year: 2014

The Ebers Papyrus, originating from about 1500 BC, is one of the oldest documents that describe the use of natural products for healing diseases. Several herbs are described in its about 700 remedies and magical formulas, for example, the squill (Urginea maritima) against dropsy (edema caused by cardiac insufficiency). Indeed, this plant contains cardiac glycosides that are beneficial in such a condition. Another important document, from the first century AD, is the book De Materia Medica of the Greek physician Dioscurides. It lists about 600 medicinal plants, 35 animal products, and 90 minerals. Obviously, these collections of remedies resulted from the accumulated experience of earlier millennia. Not all contained information is reliable; in later centuries, the wheat had to be separated from the chaff, a task that still today is not completely accomplished if we consider so many marketed herbal preparations without proven therapeutic value. On the other hand, opium, the feverlowering bark of the Cinchona tree, the foxglove (Digitalis purpurea), and many other herbal drugs remained in therapy, later being replaced by the isolated active principles morphine, quinine, digitoxin, and others. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Boschstr. All rights reserved.

Derelle R.,University Pompeu Fabra | Lang B.F.,University of Montreal
Molecular Biology and Evolution | Year: 2012

By exploiting the large body of genome data and the considerable progress in phylogenetic methodology, recent phylogenomic studies have provided new insights into the relationships among major eukaryotic groups. However, confident placement of the eukaryotic root remains a major challenge. This is due to the large evolutionary distance separating eukaryotes from their closest relatives, the Archaea, implying a weak phylogenetic signal and strong long-branch attraction artifacts. Here, we apply a new approach to the rooting of the eukaryotic tree by using a subset of genomic information with more recent evolutionary origin-mitochondrial sequences, whose closest relatives are α-Proteobacteria. For this, we identified and assembled a data set of 42 mitochondrial proteins (mainly encoded by the nuclear genome) and performed Bayesian and maximum likelihood analyses. Taxon sampling includes the recently sequenced Thecamonas trahens, a member of the phylogenetically elusive Apusozoa. This data set confirms the relationships of several eukaryotic supergroups seen before and places the eukaryotic root between the monophyletic "unikonts" and "bikonts." We further show that T. trahens branches sister to Opisthokonta with significant statistical support and question the bikont/excavate affiliation of Malawimonas species. The mitochondrial data set developed here (to be expanded in the future) constitutes a unique alternative means in resolving deep eukaryotic relationships. © 2011 The Author.

Kroeger J.,Raymor Nanotech | Geitmann A.,University of Montreal
Current Opinion in Plant Biology | Year: 2012

The polar growth process characterizing pollen tube elongation has attracted numerous modeling attempts over the past years. While initial models focused on recreating the correct cellular geometry, recent models are increasingly based on experimentally assessed cellular parameters such as the dynamics of signaling processes and the mechanical properties of the cell wall. Recent modeling attempts have therefore substantially gained in biological relevance and predictive power. Different modeling methods are explained and the power and limitations of individual models are compared. Focus is on several recent models that use closed feedback loops in order to generate limit cycles representing the oscillatory behavior observed in growing tubes. © 2012 Elsevier Ltd.

Behrmann J.,University of Montreal
Journal of School Nursing | Year: 2010

Food allergy in children is a growing public health problem that carries a significant risk of anaphylaxis such that schools and child care facilities have enacted emergency preparedness policies for anaphylaxis and methods to prevent the inadvertent consumption of allergens. However, studies indicate that many facilities are poorly prepared to handle the advent of anaphylaxis and policies for the prevention of allergen exposure are missing essential components. Furthermore, certain policies are inappropriate because they are blatantly discriminatory. This article aims to provide further guidance for school health officials involved in creating food allergy policies. By structuring policies around ethical principles of confidentiality and anonymity, fairness, avoiding stigmatization, and empowerment, policy makers gain another method to support better policy making. The main ethical principles discussed are adapted from key values in the bioethics and public health ethics literatures and will be framed within the specific context of food allergy policies for schools. © 2010 The Author(s).

Ferland G.,University of Montreal
Annals of Nutrition and Metabolism | Year: 2012

Vitamin K was discovered fortuitously in 1929 as part of experiments on sterol metabolism and was immediately associated with blood coagulation. In the decade that followed, the principal K vitamers, phylloquinone and the menaquinones, were isolated and fully characterized. In the early 1940s, the first vitamin K antagonists were discovered and crystallized with one of its derivatives, warfarin, still being widely used in today's clinical setting. However, major progress in our understanding of the mechanisms of action of vitamin K came in the 1970s with the discovery of γ-carboxyglutamic acid (Gla), a new amino acid common to all vitamin K proteins. This discovery not only provided the basis to understanding earlier findings about prothrombin but later led to the discovery of vitamin K-dependent proteins (VKDPs) not involved in hemostasis. The 1970s also saw an important breakthrough with respect to our understanding of the vitamin K cycle and marked the discovery of the first bone VKDP, osteocalcin. Important studies relating to the role of vitamin K in sphingolipid synthesis were also underway at that time and would pave the way to further work 15 years later. The decades that followed saw the discovery of additional VKDPs showing wide tissue distribution and functional scope, the latest members having been identified in 2008. The 1990s and 2000s were also marked by important epidemiological and intervention studies that focused on the translational impact of recent vitamin K discoveries, notably with respect to bone and cardiovascular health. This short review presents an overview of the history of vitamin K and of its recent developments. Copyright © 2012 S. Karger AG, Basel.

Sicotte C.,University of Montreal
Telemedicine journal and e-health : the official journal of the American Telemedicine Association | Year: 2011

To assess the impact of a home telemonitoring technology on patients with chronic obstructive pulmonary disease in terms of care satisfaction, patient empowerment, improved quality of life, and utilization of hospital and home care. A quasi-experimental retrospective and prospective design was developed with a matched control group to compare the effects of telemonitoring (the experimental group, n=23) with the traditional homecare offering (the control group, n=23). Satisfaction, patient empowerment, and quality of life were measured using validated Likert scales, whereas the data on care utilization were collected from the participating patients' medical record. Mixed results were observed. The clinical effects of home telemonitoring were very positive in terms of patients' satisfaction and empowerment. The perceptions of care providers as well as those of patients were congruent in this respect. Also, the study suggests that telemonitoring may have a positive effect on quality of life for patients with chronic obstructive pulmonary diseases. In contrast, the results were disappointing in terms of resource savings for the use of both homecare and hospital care. Capturing the full potential of these new technologies will require a much more fundamental reorganization of work than just a simple deployment of the technology.

Mac-Thiong J.M.,University of Montreal
European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society | Year: 2011

Many studies suggest the importance of the sagittal sacropelvic balance and morphology in spinal and hip disorders. This study describes the normal age- and sex-related changes in sacropelvic morphology and balance in a prospective cohort of asymptomatic adults without spinal disorder. A prospective cohort of 709 asymptomatic adults without spinal pathology was recruited. There were 354 males and 355 females aged 37.9 ± 14.7 and 35.7 ± 13.9 years, respectively. For each subjects, pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS) were measured from standing lateral radiographs. Ratios of SS to PI (SS/PI), PT to PI (PT/PI), and PT to SS (PT/SS) were also calculated. There was no significant difference in PI (pelvic incidence), SS (sacral slope), PT (pelvic tilt), PT/PI, SS/PI, or PT/SS between males and females. The mean ± 2 standard deviations (SD) range was 32°-74°, 0°-27°, and 24°-55° for PI, PT and SS, respectively. The mean ± 2 SD range was greater than 0.5 for SS/PI and less than 0.5 for PT/PI. PI was not related to age in either sex group. PT, SS, PT/PI, SS/PI, and PT/SS presented only weak correlation coefficients (r ≤ 0.21) with respect to age. The current study presents the largest cohort of asymptomatic adults in the literature dedicated to the evaluation of sagittal sacropelvic morphology and balance. The range of values corresponding to the mean ± 2 SD can provide invaluable information to clinicians about the normal range of values expected in 95% of the normal population.

Carpentier J.,University of Quebec at Trois - Rivieres | Proulx J.,University of Montreal
Sexual Abuse: Journal of Research and Treatment | Year: 2011

The present study investigates the recidivism rates of a sample of 351 male adolescents who sexually offended, and were assessed at an outpatient psychiatric clinic in Montreal, Canada, between 1992 and 2002. The mean age of the participants was 15.8 years (SD = 1.8). Data on adolescent and adult recidivism were collected in Summer 2005 from official criminality sources in Canada. Over an 8-year follow-up period, 45% (n = 158) of the participants were charged with a new criminal offense, 30% (n = 104) were charged with a violent offense, and 10% (n = 36) were charged with a sexual offense. Cox regression results suggest that overall, violent, and sexual recidivism can be predicted by a variety of developmental, social, and criminological factors. Paternal abandonment, childhood sexual victimization, association with significantly younger children, and having victimized a stranger were associated with a higher risk of sexual recidivism. Previous delinquency, attention deficit disorder, and childhood sexual victimization were found to increase the risk for both violent and overall recidivism. Also, the use of violence during a sex crime and victimizing a stranger were associated with violent recidivism, and school delay and association with delinquent peers were predictive of overall recidivism. The results confirm that a significant proportion of adolescents who have sexually offended pursue a criminal activity beyond adolescence, although few specialize in sexual offending. © The Author(s) 2011.

Ducharme F.M.,University of Montreal
Cochrane database of systematic reviews (Online) | Year: 2010

BACKGROUND: Long-acting inhaled ss(2)-adrenergic agonists (LABAs) are recommended as 'add-on' medication to inhaled corticosteroids (ICS) in the maintenance therapy of asthmatic adults and children aged two years and above. OBJECTIVES: To quantify in asthmatic patients the safety and efficacy of the addition of LABAs to ICS in patients insufficiently controlled on ICS alone. SEARCH STRATEGY: We identified randomised controlled trials (RCTs) through electronic database searches (the Cochrane Airways Group Specialised Register, MEDLINE, EMBASE and CINAHL), bibliographies of RCTs and correspondence with manufacturers until May 2008. SELECTION CRITERIA: We included RCTs if they compared the addition of inhaled LABAs versus placebo to the same dose of ICS in children aged two years and above and in adults. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed studies for methodological quality and extracted data. We obtained confirmation from the trialists when possible. The primary endpoint was the relative risk (RR) of asthma exacerbations requiring rescue oral corticosteroids. Secondary endpoints included pulmonary function tests (PFTs), rescue beta2-agonist use, symptoms, withdrawals and adverse events. MAIN RESULTS: Seventy-seven studies met the entry criteria and randomised 21,248 participants (4625 children and 16,623 adults). Participants were generally symptomatic at baseline with moderate airway obstruction despite their current ICS regimen. Formoterol or salmeterol were most frequently added to low-dose ICS (200 to 400 microg/day of beclomethasone (BDP) or equivalent) in 49% of the studies. The addition of a daily LABA to ICS reduced the risk of exacerbations requiring oral steroids by 23% from 15% to 11% (RR 0.77, 95% CI 0.68 to 0.87, 28 studies, 6808 participants). The number needed to treat with the addition of LABA to prevent one use of rescue oral corticosteroids is 41 (29, 72), although the event rates in the ICS groups varied between 0% and 38%. Studies recruiting adults dominated the analysis (6203 adult participants versus 605 children). The subgroup estimate for paediatric studies was not statistically significant (RR 0.89, 95% CI 0.58 to 1.39) and includes the possibility of the superiority of ICS alone in children.Higher than usual dose of LABA was associated with significantly less benefit. The difference in the relative risk of serious adverse events with LABA was not statistically significant from that of ICS alone (RR 1.06, 95% CI 0.87 to 1.30). The addition of LABA led to a significantly greater improvement in FEV(1) (0.11 litres, 95% 0.09 to 0.13) and in the proportion of symptom-free days (11.88%, 95% CI 8.25 to 15.50) compared to ICS monotherapy. It was also associated with a reduction in the use of rescue short-acting ss(2)-agonists (-0.58 puffs/day, 95% CI -0.80 to -0.35), fewer withdrawals due to poor asthma control (RR 0.50, 95% CI 0.41 to 0.61), and fewer withdrawals due to any reason (RR 0.80, 95% CI 0.75 to 0.87). There was no statistically significant group difference in the risk of overall adverse effects (RR 1.00, 95% 0.97 to 1.04), withdrawals due to adverse health events (RR 1.04, 95% CI 0.86 to 1.26) or any of the specific adverse health events. AUTHORS' CONCLUSIONS: In adults who are symptomatic on low to high doses of ICS monotherapy, the addition of a LABA at licensed doses reduces the rate of exacerbations requiring oral steroids, improves lung function and symptoms and modestly decreases use of rescue short-acting ss(2)-agonists. In children, the effects of this treatment option are much more uncertain. The absence of group difference in serious adverse health events and withdrawal rates in both groups provides some indirect evidence of the safety of LABAs at usual doses as add-on therapy to ICS in adults, although the width of the confidence interval precludes total reassurance.

De Leener B.,Ecole Polytechnique de Montreal | Kadoury S.,Ecole Polytechnique de Montreal | Cohen-Adad J.,Ecole Polytechnique de Montreal | Cohen-Adad J.,University of Montreal
NeuroImage | Year: 2014

Spinal cord segmentation provides measures of atrophy and facilitates group analysis via inter-subject correspondence. Automatizing this procedure enables studies with large throughput and minimizes user bias. Although several automatic segmentation methods exist, they are often restricted in terms of image contrast and field-of-view. This paper presents a new automatic segmentation method (PropSeg) optimized for robustness, accuracy and speed. The algorithm is based on the propagation of a deformable model and is divided into three parts: firstly, an initialization step detects the spinal cord position and orientation using a circular Hough transform on multiple axial slices rostral and caudal to the starting plane and builds an initial elliptical tubular mesh. Secondly, a low-resolution deformable model is propagated along the spinal cord. To deal with highly variable contrast levels between the spinal cord and the cerebrospinal fluid, the deformation is coupled with a local contrast-to-noise adaptation at each iteration. Thirdly, a refinement process and a global deformation are applied on the propagated mesh to provide an accurate segmentation of the spinal cord. Validation was performed in 15 healthy subjects and two patients with spinal cord injury, using T1- and T2-weighted images of the entire spinal cord and on multiecho T2*-weighted images. Our method was compared against manual segmentation and against an active surface method. Results show high precision for all the MR sequences. Dice coefficients were 0.9 for the T1- and T2-weighted cohorts and 0.86 for the T2*-weighted images. The proposed method runs in less than 1min on a normal computer and can be used to quantify morphological features such as cross-sectional area along the whole spinal cord. © 2014 Elsevier Inc.

Gagnon Y.,University of Montreal
BMC bioinformatics | Year: 2012

The "small phylogeny" problem consists in inferring ancestral genomes associated with each internal node of a phylogenetic tree of a set of extant species. Existing methods can be grouped into two main categories: the distance-based methods aiming at minimizing a total branch length, and the synteny-based (or mapping) methods that first predict a collection of relations between ancestral markers in term of "synteny", and then assemble this collection into a set of Contiguous Ancestral Regions (CARs). The predicted CARs are likely to be more reliable as they are more directly deduced from observed conservations in extant species. However the challenge is to end up with a completely assembled genome. We develop a new synteny-based method that is flexible enough to handle a model of evolution involving whole genome duplication events, in addition to rearrangements, gene insertions, and losses. Ancestral relationships between markers are defined in term of Gapped Adjacencies, i.e. pairs of markers separated by up to a given number of markers. It improves on a previous restricted to direct adjacencies, which revealed a high accuracy for adjacency prediction, but with the drawback of being overly conservative, i.e. of generating a large number of CARs. Applying our algorithm on various simulated data sets reveals good performance as we usually end up with a completely assembled genome, while keeping a low error rate. All source code is available at http://www.iro.umontreal.ca/~mabrouk.

Wang Z.,University of Montreal
Journal of Cardiovascular Pharmacology | Year: 2010

Cardiomyocytes are excitable cells that can generate and propagate excitations; excitability is a fundamental characteristic of these cells, which is reflected by action potential; the changes of transmembrane potential as a function of time; and orchestrated by ion channels, transporters, and cellular proteins. The electrical excitation evoked in muscles must be transformed into mechanical contraction through the so-called excitation-contraction coupling mechanism, and the proper contraction of cardiac muscles then drives pumping of blood to the body circulation. Arrhythmias are electrical disturbances that can result in irregular heart beating with consequent insufficient pumping of blood. Arrhythmias are often lethal, constituting a major cause for cardiac death, particularly sudden cardiac death, in myocardial infarction and heart failure. Recent studies have led to discovery of microRNAs (miRNAs) as a new player in the cardiac excitability by fine-tuning expression of ion channels, transporters, and cellular proteins, which determines the arrhythmogenicity in many conditions. This review article will give a comprehensive summary on the data available in the literature. The basics of cardiac excitability will first be introduced, followed by a brief introduction to the basics of miRNAs. Then, studies on regulation of cardiac excitability by miRNAs will be described and analyzed. Finally, concluding remarks will be provided. Copyright © 2010 by Lippincott Williams & Wilkins.

Reinharz V.,McGill University | Major F.,University of Montreal | Waldispuhl J.,McGill University
Bioinformatics | Year: 2012

Motivation: The prediction of RNA 3D structures from its sequence only is a milestone to RNA function analysis and prediction. In recent years, many methods addressed this challenge, ranging from cycle decomposition and fragment assembly to molecular dynamics simulations. However, their predictions remain fragile and limited to small RNAs. To expand the range and accuracy of these techniques, we need to develop algorithms that will enable to use all the structural information available. In particular, the energetic contribution of secondary structure interactions is now well documented, but the quantification of non-canonical interactions-those shaping the tertiary structure-is poorly understood. Nonetheless, even if a complete RNA tertiary structure energy model is currently unavailable, we now have catalogues of local 3D structural motifs including non-canonical base pairings. A practical objective is thus to develop techniques enabling us to use this knowledge for robust RNA tertiary structure predictors. Results: In this work, we introduce RNA-MoIP, a program that benefits from the progresses made over the last 30 years in the field of RNA secondary structure prediction and expands these methods to incorporate the novel local motif information available in databases. Using an integer programming framework, our method refines predicted secondary structures (i.e. removes incorrect canonical base pairs) to accommodate the insertion of RNA 3D motifs (i.e. hairpins, internal loops and k-way junctions). Then, we use predictions as templates to generate complete 3D structures with the MC-Sym program. We benchmarked RNA-MoIP on a set of 9 RNAs with sizes varying from 53 to 128 nucleotides. We show that our approach (i) improves the accuracy of canonical base pair predictions; (ii) identifies the best secondary structures in a pool of suboptimal structures; and (iii) predicts accurate 3D structures of large RNA molecules. © The Author(s) 2012. Published by Oxford University Press.

Daneman R.,University of California at San Diego | Prat A.,University of Montreal
Cold Spring Harbor Perspectives in Biology | Year: 2015

Blood vessels are critical to deliver oxygen and nutrients to all of the tissues and organs throughout the body. The blood vessels that vascularize the central nervous system (CNS) possess unique properties, termed the blood–brain barrier, which allow these vessels to tightly regulate the movement of ions, molecules, and cells between the blood and the brain. This precise control of CNS homeostasis allows for proper neuronal function and also protects the neural tissue from toxins and pathogens, and alterations of these barrier properties are an important component of pathology and progression of different neurological diseases. The physiological barrier is coordinated by a series of physical, transport, and metabolic properties possessed by the endothelial cells (ECs) that form the walls of the blood vessels, and these properties are regulated by interactions with different vascular, immune, and neural cells. Understanding how these different cell populations interact to regulate the barrier properties is essential for understanding how the brain functions during health and disease. © 2015 Cold Spring Harbor Laboratory Press; all rights reserved.

Ferbeyre G.,University of Montreal | Moriggl R.,Ludwig Boltzmann Research Institute
Biochimica et Biophysica Acta - Reviews on Cancer | Year: 2011

Stat5 is constitutively activated in many human cancers affecting the expression of cell proliferation and cell survival controlling genes. These oncogenic functions of Stat5 have been elegantly reproduced in mouse models. Aberrant Stat5 activity induces also mitochondrial dysfunction and reactive oxygen species leading to DNA damage. Although DNA damage can stimulate tumorigenesis, it can also prevent it. Stat5 can inhibit tumor progression like in the liver and it is a tumor suppressor in fibroblasts. Stat5 proteins are able to regulate cell differentiation and senescence activating the tumor suppressors SOCS1, p53 and PML. Understanding the context dependent regulation of tumorigenesis through Stat5 function will be central to understand proliferation, survival, differentiation or senescence of cancer cells. © 2010 Elsevier B.V.

Pelletier R.-M.,University of Montreal
Progress in Histochemistry and Cytochemistry | Year: 2011

The elucidation of how individual components of the Sertoli cell junctional complexes form and are dismantled to allow not only individual cells but whole syncytia of germinal cells to migrate from the basal to the lumenal compartment of the seminiferous epithelium without causing a permeability leak in the blood-testis barrier is amongst the most enigmatic yet, challenging and timely questions in testicular physiology. The intriguing key event in this process is how the barrier modulates its permeability during the periods of formation and dismantling of individual Sertoli cell junctions. The purpose of this review is therefore to first provide a reliable account on the normal formation, maintenance and dismantling process of the Sertoli cells junctions, then to assess the influence of the expression of their individual proteins, of the cytoskeleton associated with the junctions, and of the lipid content in the seminiferous tubules on the regulation of the their permeability barrier function. To help focus on the formation and dismantling of the Sertoli cell junctions, several considerations are based on data gleaned not only from rodents but from seasonal breeders as well because these animal models are characterized by exhaustive periods of junction assembly during development and the onset of the seasonal re-initiation of spermatogenesis as well as by an extensive junction dismantling period at the beginning of testicular regression, something unavailable in normal physiological conditions in continual breeders. Thus, the modulation of the permeability barrier function of the Sertoli cell junctions is analyzed in the physiological context of the blood-epidydimis barrier and in particular of the blood-testis barrier rather than in the context of a detailed account of the molecular composition and signalisation pathways of cell junctions. Moreover, the considerations discussed in this review are based on measurements performed on seminiferous tubule-enriched fractions gleaned at regular time intervals during development and the annual reproductive cycle. © 2011 Elsevier GmbH.

Dang-Vu T.T.,University of Liege | Dang-Vu T.T.,University of Montreal
NeuroMolecular Medicine | Year: 2012

Recent functional neuroimaging studies have investigated brain activity patterns during sleep in humans, beyond the conventionally defined sleep stages. These works have characterized the neural activations related to the major brain oscillations of sleep, that is, spindles and slow waves during non-rapid-eye-movement sleep and ponto-geniculo-occipital waves during rapid-eye-movement sleep. These phasic events have been found associated with increases of brain activity in specific neural networks, which identify structures involved in the generation of sleep oscillations. Most importantly, these results confirm that, even during the deepest stages of sleep, neuronal network activities are sustained and organized by spontaneous brain oscillations of sleep. The understanding of the neural mechanisms underlying sleep oscillations is fundamental since increasing evidence suggests a pivotal role for these rhythms in the functional properties of sleep. In particular, interactions between the sleeping brain and the surrounding environment are closely modulated by neuronal oscillations of sleep. Functional neuroimaging studies have demonstrated that spindles distort the transmission of auditory information to the cortex, therefore isolating the brain from external disturbances during sleep. In contrast, slow waves evoked by acoustic stimulation-and also termed K-complexes-are associated with larger auditory cortex activation, thus reflecting an enhanced processing of external information during sleep. Future brain imaging studies of sleep should further explore the contribution of neuronal oscillations to the off-line consolidation of memory during sleep. © 2012 Springer Science+Business Media, LLC.

Seidah N.G.,University of Montreal
Current Opinion in Lipidology | Year: 2016

PURPOSE OF REVIEW: High levels of LDL-cholesterol (LDL-C) are directly associated with devastating cardiovascular complications. Statins downregulate cholesterol synthesis and upregulate hepatic mRNA levels of LDL receptor (LDLR) and proprotein convertase subtilisin–kexin 9 (PCSK9), a validated enhancer of LDLR protein degradation. Herein, we summarize recent discoveries of the biological properties of PCSK9 in both health and disease states. RECENT FINDINGS: PCSK9 downregulation of the LDLR protein likely explains the observed protective effect of the loss of PCSK9 in reducing lipoprotein(a) and incidence of septic shock. Injectable inhibitory PCSK9 monoclonal antibodies are now prescribed to hypercholesterolemic patients that do not reach target levels of LDL-C with available drugs. PCSK9 also reduces the levels of other receptors, for example, VLDL receptor (VLDLR), ApoER2, CD36, and CD81. The efficacy of the upregulation of LDLR and VLDLR cell surface levels in the absence of PCSK9 is both tissue and sex dependent. As LDLR, CD81, and VLDLR are hepatitis C receptors, PCSK9 may protect against certain viral infections. SUMMARY: New functions of PCSK9 and other receptor targets are beginning to emerge to explain the observed changes in LDL-C and triglycerides. The effect of PCSK9 loss-of-function on glucose metabolism, factors that regulate the expression of PCSK9, and the roles of PCSK9 in other tissues, for example, intestine, kidney, and brain require further investigations. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.

Simonet F.,University of Montreal
International journal of circumpolar health | Year: 2012

The objective was to assess trends in Inuit, First Nations and non-Aboriginal birth outcomes in the rural and northern regions of Quebec. In a birth cohort-based study of all births to residents of rural and northern Quebec from 1991 through 2000 (n = 177,193), we analyzed birth outcomes and infant mortality for births classified by maternal mother tongue (Inuit, First Nations or non-Aboriginal) and by community type (predominantly First Nations, Inuit or non-Aboriginal). From 1991-1995 to 1996-2000, there was a trend of increasing rates of preterm birth for all 6 study groups. In all rural and northern areas, low birth weight rates increased significantly only for the Inuit mother tongue group [RR1.45 (95% CI 1.05-2.01)]. Stillbirth rates showed a non-significant increase for the Inuit mother tongue group [RR1.76 (0.64-4.83)]. Neonatal mortality rates decreased significantly in the predominantly non-Aboriginal communities and in the non-Aboriginal mother tongue group [RR0.78 (0.66-0.92)], and increased non-significantly for the First Nations mother tongue group [RR2.17 (0.71-6.62)]. Perinatal death rates increased for the First Nations mother tongue grouping in northern areas [RR2.19 (0.99-4.85)]. There was a disconcerting rise of some mortality outcomes for births to First Nations and Inuit mother tongue women and to women in predominantly First Nations and Inuit communities, in contrast to some improvements for births to non-Aboriginal mother tongue women and to women in predominantly non-Aboriginal communities in rural or northern Quebec, indicating a need for improving perinatal and neonatal health for Aboriginal populations in rural and northern regions.

Gagnon A.,University of Montreal
American Journal of Human Biology | Year: 2012

Objectives: Individuals with fetal growth restrictions may become unhealthy as adult if they live in a nutritionally rich environment. Yet, there is little evidence for the counterpart that profuse resources during early development may prove detrimental in an impoverished adult environment. Using birth season as a proxy for nutrition in utero, this study tests whether early life effects on longevity are conditional on the environment in which people reside during adulthood. Methods: I used Cox proportional hazard models of mortality after the age of 60 years among historical cohorts of French Canadian women born before 1750. Models are stratified by siblings to adjust the results for unobserved factors shared by family members. Results: A birth during winter conferred the best-survival prospects in the south of the Saint-Lawrence River but the worse prospects in the north, where a birth during the fall was associated with the lowest mortality. Women who migrated to live on the other side of the river lost whatever advantage or disadvantage they had from their birth season and faced increases or decreases in risk that were specific to their new location. Conclusions: Based on Hales and Barker's thrifty phenotype hypothesis, and adding the "hopeful phenotype" counterpart, this study suggests that cues from the external environment during development are highly specific to that environment and that the slightest change of location may affect the chances for survival into old age. I finally address the role of fertility as a possible mediator or modifier of the effect of birth season on longevity. © 2012 Wiley Periodicals, Inc.

Lartillot N.,University of Montreal | Lartillot N.,CNRS Montpellier Laboratory of Informatics, Robotics and Microelectronics
Molecular Biology and Evolution | Year: 2013

According to the nearly-neutral model, variation in long-term effective population size among species should result in correlated variation in the ratio of nonsynonymous over synonymous substitution rates (dN/dS). Previous empirical investigations in mammals have been consistent with this prediction, suggesting an important role for nearly-neutral effects on protein-coding sequence evolution. GC-biased gene conversion (gBGC), on the other hand, is increasingly recognized as a major evolutionary force shaping genome nucleotide composition. When sufficiently strong compared with random drift, gBGC may significantly interfere with a nearly-neutral regime and impact dN/dS in a complex manner. Here, we investigate the phylogenetic correlations between dN/dS, the equilibrium GC composition (GC*), and several life-history and karyotypic traits in placental mammals. We show that the equilibrium GC composition decreases with body mass and increases with the number of chromosomes, suggesting a modulation of the strength of biased gene conversion due to changes in effective population size and genome-wide recombination rate. The variation in dN/dS is complex and only partially fits the prediction of the nearly-neutral theory. However, specifically restricting estimation of the dN/dS ratio on GC-conservative transversions, which are immune from gBGC, results in correlations that are more compatible with a nearly-neutral interpretation. Our investigation indicates the presence of complex interactions between selection and biased gene conversion and suggests that further mechanistic development is warranted, to tease out mutation, selection, drift, and conversion. © The Author 2012.

ABSTRACT: The genetic metabolic disease mucopolysaccharidosis III type C (MPS IIIC, Sanfilippo disease type C) causes progressive neurodegeneration in infants and children, leading to dementia and death before adulthood. MPS IIIC stands out among lysosomal diseases because it is the only one caused by a deficiency not of a hydrolase but of HGSNAT (heparan--glucosaminide N-acetyltransferase), which catalyzes acetylation of glycosaminoglycan heparan sulfate (HS) prior to its hydrolysis. © 2016 Taylor & Francis.

Gong Y.-K.,Northwest University, China | Winnik F.M.,University of Montreal | Winnik F.M.,Japan National Institute of Materials Science
Nanoscale | Year: 2012

Engineered nanoparticles (NPs) play an increasingly important role in biomedical sciences and in nanomedicine. Yet, in spite of significant advances, it remains difficult to construct drug-loaded NPs with precisely defined therapeutic effects, in terms of release time and spatial targeting. The body is a highly complex system that imposes multiple physiological and cellular barriers to foreign objects. Upon injection in the blood stream or following oral administation, NPs have to bypass numerous barriers prior to reaching their intended target. A particularly successful design strategy consists in masking the NP to the biological environment by covering it with an outer surface mimicking the composition and functionality of the cell's external membrane. This review describes this biomimetic approach. First, we outline key features of the composition and function of the cell membrane. Then, we present recent developments in the fabrication of molecules that mimic biomolecules present on the cell membrane, such as proteins, peptides, and carbohydrates. We present effective strategies to link such bioactive molecules to the NPs surface and we highlight the power of this approach by presenting some exciting examples of biomimetically engineered NPs useful for multimodal diagnostics and for target-specific drug/gene delivery applications. Finally, critical directions for future research and applications of biomimetic NPs are suggested to the readers. © 2012 The Royal Society of Chemistry.

Du Souich P.,University of Montreal
Pharmacology and Therapeutics | Year: 2014

Symptomatic Slow Acting Drugs for Osteoarthritis (SYSADOA), such as hyaluronic acid (HA), chondroitin sulfate (CS) and glucosamine (GlcN) are natural compounds, composed of repeating disaccharides, used to treat patients with osteoarthritis (OA). Many questions about the kinetics and mechanism of action of SYSADOA remain poorly answered. This review examines the data supporting oral absorption and body distribution of SYSADOA, and discusses their mechanism of action. SYSADOA are absorbed in the small intestine with a bioavailability ranging from 5 to 45% and accumulate in articular tissues. The mechanism of action of HA and CS differs in several aspects from that of GlcN. Being large molecules, HA and CS do not penetrate into chondrocytes, synoviocytes, osteoblast, osteoclast and osteocytes, and so elicit the anti-inflammatory effect by engaging membrane receptors, e.g. CD44, TLR4, and ICAM1, with a resulting dual effect: impede the fragments of extracellular matrix engaging these receptors, cause of inflammatory reaction, and block the signal transduction pathways activated by the fragments and so diminish the nuclear translocation of pro-inflammatory transcription factors. GlcN penetrates into cells by means of glucose transporters. The primary effect of GlcN is associated to its ability to O-GlcNAcylate proteins and as a consequence, modulates their activity, e.g. decrease nuclear factor-κB nuclear translocation. GlcN may also affect the transcription of pro-inflammatory cytokines by epigenetic mechanisms. The characteristics of the mechanism of action support the use of CS combined with GlcN, and suggest that HA and CS shall be more effective in initial phases of OA. © 2014 Elsevier Inc. All rights reserved.

Goriely S.,Free University of Colombia | Chamel N.,Free University of Colombia | Pearson J.M.,University of Montreal
Physical Review C - Nuclear Physics | Year: 2013

We present a new Hartree-Fock-Bogoliubov nuclear mass model based on standard forms of Skyrme and pairing functionals, which corresponds to the most accurate mass model we ever achieved within the framework of the nuclear energy density functional theory. Our new mass model is characterized by a model standard deviation σmod=0.500 MeV with respect to essentially all the 2353 available mass data for nuclei with neutron and proton numbers larger than 8. At the same time, the underlying Skyrme functional yields a realistic description of infinite homogeneous nuclear matter properties, as determined by realistic calculations and by experiments; these include in particular the incompressibility coefficient, the pressure in charge-symmetric nuclear matter, the neutron-proton effective mass splitting, the stability against spin and spin-isospin fluctuations, as well as the neutron-matter equation of state. © 2013 American Physical Society.

Butterworth R.F.,University of Montreal
Journal of Clinical and Experimental Hepatology | Year: 2015

Neuropathologic investigations in acute liver failure (ALF) reveal significant alterations to neuroglia consisting of swelling of astrocytes leading to cytotoxic brain edema and intracranial hypertension as well as activation of microglia indicative of a central neuroinflammatory response. Increased arterial ammonia concentrations in patients with ALF are predictors of patients at risk for the development of brain herniation. Molecular and spectroscopic techniques in ALF reveal alterations in expression of an array of genes coding for neuroglial proteins involved in cell volume regulation and mitochondrial function as well as in the transport of neurotransmitter amino acids and in the synthesis of pro-inflammatory cytokines. Liver-brain pro-inflammatory signaling mechanisms involving transduction of systemically-derived cytokines, ammonia neurotoxicity and exposure to increased brain lactate have been proposed. Mild hypothermia and N-Acetyl cysteine have both hepato-protective and neuro-protective properties in ALF. Potentially effective anti-inflammatory agents aimed at control of encephalopathy and brain edema in ALF include etanercept and the antibiotic minocycline, a potent inhibitor of microglial activation. Translation of these potentially-interesting findings to the clinic is anxiously awaited. © 2014 INASL.

Huneault L.,Laval University | Mathieu M.-E.,University of Montreal | Tremblay A.,Laval University
Obesity Reviews | Year: 2011

Animal research has well established that a link exists between variations in corticosteroids and the proneness to excess body fat accumulation. Accordingly, it is known that adrenalectomy is an efficient approach to counteract weight gain in most animal models of obesity. In humans, the association between variations in corticosteroids, its stress-related environmental effects and the predisposition to obesity is more difficult to demonstrate. In this paper, we propose that this relationship is accentuated by globalization and modernization which favour a labour context imposing additional stress and changes in life habits promoting a positive energy balance. Our main hypothesis is that the increase in knowledge-based work, and the decrease of quality and duration of sleep both induce an increase in cortisolaemia and glycaemia instability, which results in an increase in food intake, a reduction in energy expenditure and body fat gain. The authors of this paper believe that, from a socioeconomic perspective, globalization leads every nation of the world in conflict with itself and may consequently represent a real problem. On one hand, there are preoccupations related to productivity and money making. On the other hand, people have to adopt a daily lifestyle leading to hyperphagia and decreased energy expenditure in order to maintain their economic competitiveness. © 2011 The Authors. obesity reviews © 2011 International Association for the Study of Obesity.

Tremblay-Savard O.,University of Montreal
BMC bioinformatics | Year: 2012

Understanding the history of a gene family that evolves through duplication, speciation, and loss is a fundamental problem in comparative genomics. Features such as function, position, and structural similarity between genes are intimately connected to this history; relationships between genes such as orthology (genes related through a speciation event) or paralogy (genes related through a duplication event) are usually correlated with these features. For example, recent work has shown that in human and mouse there is a strong connection between function and inparalogs, the paralogs that were created since the speciation event separating the human and mouse lineages. Methods exist for detecting inparalogs that either use information from only two species, or consider a set of species but rely on clustering methods. In this paper we present a graph-theoretic approach for finding lower bounds on the number of inparalogs for a given set of species; we pose an edge covering problem on the similarity graph and give an efficient 2/3-approximation as well as a faster heuristic. Since the physical position of inparalogs corresponding to recent speciations is not likely to have changed since the duplication, we also use our predictions to estimate the types of duplications that have occurred in some vertebrates and drosophila.

Swenson K.M.,University of Montreal
BMC bioinformatics | Year: 2012

Reconciliation is the classical method for inferring a duplication and loss history from a set of extant genes. It is based upon the notion of embedding the gene tree into the species tree, the incongruence between the two indicating evidence for duplication and loss. However, results obtained by this method are highly dependent upon the considered species and gene trees. Thus, painstaking attention has been given to the development of methods for reconstructing accurate gene trees. This paper highlights the fact that errors in gene trees are not the only reasons for the inference of an erroneous duplication-loss history. More precisely, we prove that, under certain reasonable hypotheses based on the widely accepted link between function and sequence constraints, even a well-supported gene tree yield a reconciliation that does not correspond to the true history. We then provide the theoretical underpinnings for a conservative approach to infer histories given such gene trees. We apply our method to the mammalian interleukin-1 (IL) gene tree, that has been used as a model example to illustrate the role of reconciliation.

Lecun Y.,Facebook | Lecun Y.,New York University | Bengio Y.,University of Montreal | Hinton G.,Google | Hinton G.,Kings College
Nature | Year: 2015

Deep learning allows computational models that are composed of multiple processing layers to learn representations of data with multiple levels of abstraction. These methods have dramatically improved the state-of-the-art in speech recognition, visual object recognition, object detection and many other domains such as drug discovery and genomics. Deep learning discovers intricate structure in large data sets by using the backpropagation algorithm to indicate how a machine should change its internal parameters that are used to compute the representation in each layer from the representation in the previous layer. Deep convolutional nets have brought about breakthroughs in processing images, video, speech and audio, whereas recurrent nets have shone light on sequential data such as text and speech. © 2015 Macmillan Publishers Limited. All rights reserved.

Riglioni D.,University of Montreal
Journal of Physics A: Mathematical and Theoretical | Year: 2013

The N-dimensional generalization of Bertrand spaces as families of maximally superintegrable (M.S.) systems on spaces with a nonconstant curvature is analyzed. Considering the classification of two-dimensional radial systems admitting three constants of motion at most quadratic in momenta, we will be able to generate a new class of spherically symmetric M.S. systems by using a technique based on coalgebra. The three-dimensional realization of these systems provides the entire classification of classical spherically symmetric M.S. systems admitting periodic trajectories. We show that in dimension N > 2, these systems (classical and quantum) admit, in general, higher order constants of motion and turn out to be exactly solvable. Furthermore, it is possible to obtain non-radial M.S. systems by introducing the projection of the original radial system to a suitable lower dimensional space. © 2013 IOP Publishing Ltd.

Bibeau G.,University of Montreal
Journal of Medicine and Philosophy | Year: 2011

Genomics has brought biology, medicine, agriculture, psychology, anthropology, and even philosophy to a new threshold. In this new context, the question about "what is human in humans" may end up being answered by geneticists, specialists of technoscience, and owners of biotech companies. The author defends, in this article, the idea that humanity is at risk in our age of genetic engineering, biotechnologies, and market-geared genetic research; he also argues that the values at the very core of our postgenomic era bring to its peak the science-based ideology that has developed since the time of Galileo, Newton, Descartes, and Harvey; finally, it shows that the bioindustry has invented a new genomythology that goes against the scientific evidence produced by the research in human sciences in which life is interpreted as a language. © 2011 The Author.

Tannenbaum C.,University of Montreal | Johnell K.,Karolinska Institutet
Drugs and Aging | Year: 2014

Up to 50 % of heart failure patients suffer from lower urinary tract symptoms. Urinary incontinence has been associated with worse functional status in patients with heart failure, occurring three times more frequently in patients with New York Heart Association Class III and IV symptoms compared with those with milder disease. The association between heart failure and urinary symptoms may be directly attributable to worsening heart failure pathophysiology; however, medications used to treat heart failure may also indirectly provoke or exacerbate urinary symptoms. This type of drug-disease interaction, in which the treatment for heart failure precipitates incontinence, and removal of medications to relieve incontinence worsens heart failure, can be termed therapeutic competition. The mechanisms by which heart failure medication such as diuretics, angiotensin-converting enzyme (ACE) inhibitors and β-blockers aggravate lower urinary tract symptoms are discussed. Initiation of a prescribing cascade, whereby antimuscarinic agents or β3-agonists are added to treat symptoms of urinary urgency and incontinence, is best avoided. Recommendations and practical tips are provided that outline more judicious management of heart failure patients with lower urinary tract symptoms. Compelling strategies to improve urinary outcomes include titrating diuretics, switching ACE inhibitors, treating lower urinary tract infections, appropriate fluid management, daily weighing, and uptake of pelvic floor muscle exercises. © 2013 The Author(s).

Saad F.,University of Montreal
Nature Reviews Gastroenterology and Hepatology | Year: 2015

The past 5 years have seen some of the most significant changes in the way we view and treat prostate cancer. 2014 continues in the same spirit and will be remembered as a landmark year for practice changing studies reporting their results in surgery, chemotherapy and novel medical therapies. © 2015 Macmillan Publishers Limited.

Cloutier P.,Institute Of Recherches Cliniques Of Montreal Ircm | Lavallee-Adam M.,McGill University | Faubert D.,Institute Of Recherches Cliniques Of Montreal Ircm | Blanchette M.,McGill University | And 2 more authors.
PLoS Genetics | Year: 2013

Methylation is a post-translational modification that can affect numerous features of proteins, notably cellular localization, turnover, activity, and molecular interactions. Recent genome-wide analyses have considerably extended the list of human genes encoding putative methyltransferases. Studies on protein methyltransferases have revealed that the regulatory function of methylation is not limited to epigenetics, with many non-histone substrates now being discovered. We present here our findings on a novel family of distantly related putative methyltransferases. Affinity purification coupled to mass spectrometry shows a marked preference for these proteins to associate with various chaperones. Based on the spectral data, we were able to identify methylation sites in substrates, notably trimethylation of K135 of KIN/Kin17, K561 of HSPA8/Hsc70 as well as corresponding lysine residues in other Hsp70 isoforms, and K315 of VCP/p97. All modification sites were subsequently confirmed in vitro. In the case of VCP, methylation by METTL21D was stimulated by the addition of the UBX cofactor ASPSCR1, which we show directly interacts with the methyltransferase. This stimulatory effect was lost when we used VCP mutants (R155H, R159G, and R191Q) known to cause Inclusion Body Myopathy with Paget's disease of bone and Fronto-temporal Dementia (IBMPFD) and/or familial Amyotrophic Lateral Sclerosis (ALS). Lysine 315 falls in proximity to the Walker B motif of VCP's first ATPase/D1 domain. Our results indicate that methylation of this site negatively impacts its ATPase activity. Overall, this report uncovers a new role for protein methylation as a regulatory pathway for molecular chaperones and defines a novel regulatory mechanism for the chaperone VCP, whose deregulation is causative of degenerative neuromuscular diseases. © 2013 Cloutier et al.

INTRODUCTION:: Proprotein convertase subtilisin/kexin type 9 (PCSK9) targets lipoprotein receptors for degradation, thereby reducing hepatic lipid clearance. PCSK9 inhibition reduces mortality in septic mice, presumably through increased hepatic clearance of pathogen lipids due to increased lipoprotein receptor concentrations. However, PCSK9 overexpression in vivo has not been studied in sepsis. Therefore, this study aimed to evaluate the effects of differential PCSK9 expression on systemic infection, inflammation and coagulation in sepsis. METHODS:: Wild-type, PCSK9 knockout (KO), and transgenic (Tg) mice that overexpress PCSK9 were subjected to sham surgery or cecal ligation and puncture (CLP). Bacterial loads were measured in lungs, peritoneal cavity fluid, and blood. Organ pathology was assessed in lungs, liver and kidneys. Lung myeloperoxidase activity, and plasma concentrations of alanine aminotransferase (ALT), creatinine, cell-free DNA (cfDNA), protein C, thrombin-antithrombin (TAT) complexes, interleukin (IL)-6, and IL-10 were also measured six hours post-operatively. Morbidity was assessed for 16?hours following CLP. RESULTS:: Overexpression of PCSK9 in mice increased liver and kidney pathology, plasma IL-6, ALT, and TAT concentrations during sepsis, whereas PCSK9 KO mice exhibited reduced bacterial loads, lung and liver pathology, myeloperoxidase activity, and plasma IL-10, cfDNA during CLP-induced sepsis. All septic mice had reduced plasma levels of protein C, but the protein C ratio relative to normal was significantly decreased in PCSK9 Tg mice. Dyspnea, cyanosis, and overall grimace scores were greatest in septic mice overexpressing PCSK9, whereas PCSK9 KO mice retained core body temperature during sepsis. CONCLUSION:: These findings demonstrate that PCSK9 deficiency confers protection against systemic bacterial dissemination, organ pathology and tissue inflammation, particularly in the lungs and liver, while PCSK9 overexpression exacerbates multi-organ pathology as well as the hypercoagulable and pro-inflammatory states in early sepsis. © 2016 by the Shock Society

Pascanu R.,University of Montreal | Jaeger H.,Jacobs University Bremen
Neural Networks | Year: 2011

Neurodynamical models of working memory (WM) should provide mechanisms for storing, maintaining, retrieving, and deleting information. Many models address only a subset of these aspects. Here we present a rather simple WM model in which all of these performance modes are trained into a recurrent neural network (RNN) of the echo state network (ESN) type. The model is demonstrated on a bracket level parsing task with a stream of rich and noisy graphical script input. In terms of nonlinear dynamics, memory states correspond, intuitively, to attractors in an input-driven system. As a supplementary contribution, the article proposes a rigorous formal framework to describe such attractors, generalizing from the standard definition of attractors in autonomous (input-free) dynamical systems. © 2010 Elsevier Ltd.

Bockenhauer D.,University College London | Bichet D.G.,University of Montreal
American Journal of Physiology - Renal Physiology | Year: 2013

The study of human physiology is paramount to understanding disease and developing rational and targeted treatments. Conversely, the study of human disease can teach us a lot about physiology. Investigations into primary inherited nephrogenic diabetes insipidus (NDI) have contributed enormously to our understanding of the mechanisms of urinary concentration and identified the vasopressin receptor AVPR2, as well as the water channel aquaporin-2 (AQP2), as key players in water reabsorption in the collecting duct. Yet, there are also secondary forms of NDI, for instance as a complication of lithium treatment. The focus of this review is secondary NDI associated with inherited human diseases, such as Bartter syndrome or apparent mineralocorticoid excess. Currently, the underlying pathophysiology of this inherited secondary NDI is unclear, but there appears to be true AQP2 deficiency. To better understand the underlying mechanism(s), collaboration between clinical and experimental physiologists is essential to further investigate these observations in appropriate experimental models.© 2013 the American Physiological Society.

Music N.,University of Montreal
Animal health research reviews / Conference of Research Workers in Animal Diseases | Year: 2010

Porcine reproductive and respiratory syndrome (PRRS) is an economically devastating viral disease affecting the swine industry worldwide. The etiological agent, PRRS virus (PRRSV), possesses a RNA viral genome with nine open reading frames (ORFs). The ORF1a and ORF1b replicase-associated genes encode the polyproteins pp1a and pp1ab, respectively. The pp1a is processed in nine non-structural proteins (nsps): nsp1α, nsp1β, and nsp2 to nsp8. Proteolytic cleavage of pp1ab generates products nsp9 to nsp12. The proteolytic pp1a cleavage products process and cleave pp1a and pp1ab into nsp products. The nsp9 to nsp12 are involved in virus genome transcription and replication. The 3' end of the viral genome encodes four minor and three major structural proteins. The GP(2a), GP and GP (encoded by ORF2a, 3 and 4), are glycosylated membrane associated minor structural proteins. The fourth minor structural protein, the E protein (encoded by ORF2b), is an unglycosylated membrane associated protein. The viral envelope contains two major structural proteins: a glycosylated major envelope protein GP(encoded by ORF5) and an unglycosylated membrane M protein (encoded by ORF6). The third major structural protein is the nucleocapsid N protein (encoded by ORF7). All PRRSV non-structural and structural proteins are essential for virus replication, and PRRSV infectivity is relatively intolerant to subtle changes within the structural proteins. PRRSV virulence is multigenic and resides in both the non-structural and structural viral proteins. This review discusses the molecular characteristics, biological and immunological functions of the PRRSV structural and nsps and their involvement in the virus pathogenesis.

Carra M.C.,University of Montreal
Journal of orofacial pain | Year: 2012

Sleep bruxism, a well-known burden for dentists, is commonly observed in pediatric populations. Dentists are responsible for the detection and prevention of the detrimental consequences on the stomatognathic system that may occur in some patients with sleep bruxism. However, sleep bruxism is much more than tooth wear, since it is frequently associated with orofacial pain, headaches, and other more severe sleep disorders, such as sleep-disordered breathing. Although the mechanisms underlying the possible interactions among sleep bruxism, headaches, and sleep-disordered breathing need further research, these conditions are often concomitant. A literature search was performed to identify relevant publications related to the topic, which have been integrated in this topical review. The aim of this article was to provide a brief overview on sleep bruxism, headaches, and sleep-disordered breathing in pediatric patients and to promote a multispecialist approach (including dentists, sleep specialist physicians, and psychologists) in the diagnosis and management of these frequently associated disorders.

Peronnet F.,University of Montreal
Deutsche Zeitschrift fur Sportmedizin | Year: 2010

During high intensity short duration exercise, lactate (LA) accumulates at high concentrations ([LA]) because the contribution of anaerobic glycolysis to the ATP yield is large and LA clearance is much higher than LA production. Hydrolysis of glycolytic ATP releases H+ which reduces muscle and arterial pH but in this type of exercise, higher [LA] is associated with better performances. For longer exercises at lower intensity the contribution of anaerobic metabolism to ATP yield is low but [LA] also increases and, for a given workload, is higher when O2 availability and/or delivery is low and/or mitochondrial ATP production is impaired, and it has been suggested that LA accumulation during prolonged exercise reflects a deficit in aerobic ATP, and production of anaerobic ATP. An alternate explanation is that [LA] reflects the magnitude of homeostasis disturbances which translate into "error signals" for the stimulation of mitochondrial respiration: increase in redox potential and reduction in phosphate potential.This hypothesis is consistent with the observation that lower [LA] (hence smaller homeostasis disturbances) is associated with better endurance performances (although LA per se probably doesh not contribute to fatigue). LA produced in some working muscles during prolonged exercise, is released into the blood and taken up to be oxidized in other working muscles and/or other organs and tissues (lactate shuttle), thus sustaining aerobic metabolism. A portion can also be converted into glucose in the liver (Cori cycle) to sustain plasma glucose concentration. A great deal of attention has been paid to the relationship between [LA] and power output during ramp exercise, and a lot of effort and ingenuity have been invested to identify anaerobic and/or lactate thresholds which remain elusive and putative.

Mignotte M.,University of Montreal
IEEE Transactions on Image Processing | Year: 2010

This paper presents a novel segmentation approach based on a Markov random field (MRF) fusion model which aims at combining several segmentation results associated with simpler clustering models in order to achieve a more reliable and accurate segmentation result. The proposed fusion model is derived from the recently introduced probabilistic Rand measure for comparing one segmentation result to one or more manual segmentations of the same image. This non-parametric measure allows us to easily derive an appealing fusion model of label fields, easily expressed as a Gibbs distribution, or as a nonstationary MRF model defined on a complete graph. Concretely, this Gibbs energy model encodes the set of binary constraints, in terms of pairs of pixel labels, provided by each segmentation results to be fused. Combined with a prior distribution, this energy-based Gibbs model also allows for definition of an interesting penalized maximum probabilistic rand estimator with which the fusion of simple, quickly estimated, segmentation results appears as an interesting alternative to complex segmentation models existing in the literature. This fusion framework has been successfully applied on the Berkeley image database. The experiments reported in this paper demonstrate that the proposed method is efficient in terms of visual evaluation and quantitative performance measures and performs well compared to the best existing state-of-the-art segmentation methods recently proposed in the literature. © 2010 IEEE.

Fillion-Gourdeau F.,University of Montreal | Lorin E.,Carleton University | Bandrauk A.D.,Universite de Sherbrooke
Physical Review Letters | Year: 2013

A new mechanism for the production of electron-positron pairs from the interaction of a laser field and a fully ionized diatomic molecule in the tunneling regime is presented. When the laser field is turned off, the Dirac operator has resonances in both the positive and the negative energy continua while bound states are in the mass gap. When this system is immersed in a strong laser field, the resonances move in the complex energy plane: the negative energy resonances are pushed to higher energies while the bound states are Stark shifted. It is argued here that there is a pair production enhancement at the crossing of resonances by looking at a simple one-dimensional model: the nuclei are modeled simply by Dirac delta potential wells while the laser field is assumed to be static and of finite spatial extent. The average rate for the number of electron-positron pairs produced is evaluated and the results are compared to the one and zero nucleus cases. It is shown that positrons are produced by the resonantly enhanced pair production mechanism, which is analogous to the resonantly enhanced ionization of molecular physics. This phenomenon could be used to increase the number of pairs produced at low field strength, allowing the study of the Dirac vacuum. © 2013 American Physical Society.

Boc A.,University of Quebec at Montreal | Philippe H.,University of Montreal | Makarenkov V.,University of Quebec at Montreal
Systematic Biology | Year: 2010

Horizontal gene transfer (HGT) is one of the main mechanisms driving the evolution of microorganisms. Its accurate identification is one of the major challenges posed by reticulate evolution. In this article, we describe a new polynomial-time algorithm for inferring HGT events and compare 3 existing and 1 new tree comparison indices in the context of HGT identification. The proposed algorithm can rely on different optimization criteria, including least squares (LS), Robinson and Foulds (RF) distance, quartet distance (QD), and bipartition dissimilarity (BD), when searching for an optimal scenario of subtree prune and regraft (SPR) moves needed to transform the given species tree into the given gene tree. As the simulation results suggest, the algorithmic strategy based on BD, introduced in this article, generally provides better results than those based on LS, RF, and QD. The BD-based algorithm also proved to be more accurate and faster than a well-known polynomial time heuristic RIATA-HGT. Moreover, the HGT recovery results yielded by BD were generally equivalent to those provided by the exponential-time algorithm LatTrans, but a clear gain in running time was obtained using the new algorithm. Finally, a statistical framework for assessing the reliability of obtained HGTs by bootstrap analysis is also presented.

Ragsdale D.W.,University of Minnesota | Landis D.A.,Michigan State University | Brodeur J.,University of Montreal | Heimpel G.E.,University of Minnesota | Desneux N.,French National Institute for Agricultural Research
Annual Review of Entomology | Year: 2011

The soybean aphid, Aphis glycines Matsumura, has become the single most important arthropod pest of soybeans in North America. Native to Asia, this invasive species was first discovered in North America in July 2000 and has rapidly spread throughout the northcentral United States, much of southeastern Canada, and the northeastern United States. In response, important elements of the ecology of the soybean aphid in North America have been elucidated, with economic thresholds, sampling plans, and chemical control recommendations widely adopted. Aphid-resistant soybean varieties were available to growers in 2010. The preexisting community of aphid natural enemies has been highly effective in pressing aphid populations in many situations, and classical biological control efforts have focused on the addition of parasitoids of Asian origin. The keys to sustainable management of this pest include understanding linkages between the soybean aphid and other introduced and native species in a landscape context along with continued development of aphid-resistant varieties. © 2011 by Annual Reviews. All rights reserved.

Gronau M.,Technion - Israel Institute of Technology | London D.,University of Montreal | Rosner J.L.,University of Chicago
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Several B and Bs decays have been observed that have been cited as evidence for exchange (E), penguin annihilation (PA), and annihilation (A) processes, such as b̄d→ūu, b̄s→ūu, and b̄u→W*→c̄s, respectively. These amplitudes are normally thought to be suppressed, as they involve the spectator quark in the weak interaction and thus should be proportional to the B-meson decay constant fB. However, as pointed out a number of years ago, they can also be generated by rescattering from processes whose amplitudes do not involve fB, such as color-favored tree amplitudes. In this paper we investigate a number of processes such as B0→K+K-, Bs→π+π-, and B +→Ds+φ, and identify promising states from which they can be generated by rescattering. We find that E-and PA-type processes are characterized, respectively, by amplitudes ranging from 5% to 10% and from 15% to 20% with respect to the largest amplitude from which they can rescatter. Based on this regularity, using approximate flavor SU(3) symmetry in some cases and time-reversal invariance in others, we predict the branching fractions for a large number of as-yet-unseen B and Bs decays in an extensive range from order 10-9 to 10-4. © 2013 American Physical Society.

Jacques M.,University of Montreal
Animal health research reviews / Conference of Research Workers in Animal Diseases | Year: 2010

Bacterial biofilms are structured communities of bacterial cells enclosed in a self-produced polymer matrix that is attached to a surface. Biofilms protect and allow bacteria to survive and thrive in hostile environments. Bacteria within biofilms can withstand host immune responses, and are much less susceptible to antibiotics and disinfectants when compared with their planktonic counterparts. The ability to form biofilms is now considered a universal attribute of micro-organisms. Diseases associated with biofilms require novel methods for their prevention, diagnosis and treatment; this is largely due to the properties of biofilms. Surprisingly, biofilm formation by bacterial pathogens of veterinary importance has received relatively little attention. Here, we review the current knowledge of bacterial biofilms as well as studies performed on animal pathogens.

5-Aza-2′-deoxycytidine (5-AZA-CdR, decitabine, Dacogen®) and 5-azacytidine (5-AC, Vidaza®) are epigenetic agents that have been approved for the clinical treatment of the hematological malignancy myelodysplastic syndrome (MDS) and are currently under clinical evaluation for the treatment of acute myeloid leukemia (AML). Most investigators currently classify 5-AZA-CdR and 5-AC as inhibitors of DNA methylation, which can reactivate tumor suppressor genes silenced by this epigenetic event. Examination of the pharmacology of these analogues reveals important differences with respect to their molecular mechanism of action. The action of 5-AZA-CdR is due to its incorporation into DNA. 5-AC is a riboside analogue that is incorporated primarily into RNA. A small fraction of 5-AC is converted to its deoxyribose form by ribonucleotide reductase and subsequently incorporated into DNA. The incorporation of 5-AC into RNA can interfere with the biological function of RNA and result in an inhibition protein synthesis. Microarray analysis revealed that both these analogues target the expression of different cohorts of genes. Preclinical studies show that 5-AZA-CdR is a more effective antileukemic agent than 5-AC. One explanation for this observation is that 5-AC blocks the progression of some leukemic cells from G 1 into S phase, and this protects these cells from the chemotherapeutic action of this riboside analogue related to its incorporation into DNA. However, differences in chemotherapeutic efficacy of these related analogues have not been clearly demonstrated in clinical trials in patients with hematological malignancies. These observations should be taken into consideration in the design of new clinical trials using 5-AZA-CdR or 5-AC in patients with MDS and AML. © 2012 by the authors; licensee MDPI, Basel, Switzerland.

Chaurand P.,University of Montreal
Journal of Proteomics | Year: 2012

Imaging mass spectrometry (MS) allows to monitor the spatial distribution and abundance of endogenous and administered compounds present within tissue specimens. Several different but complementary imaging MS technologies have been developed allowing the analysis of a wide variety of compounds including inorganic elementals, metabolites, lipids, peptides, proteins and xenobiotics with spatial resolutions from micrometer to nanometer scales. In the past decade, an enormous collective body of work has been done to develop and improve the imaging MS technology. This article gives a historical perspective, an overview of the principle and status of the technology and lists the main fields of applications. It also enumerates some of the critical challenges we need to collectively address for imaging MS to be considered a mainstream analytical method.This article is part of a Special Issue entitled: Imaging Mass Spectrometry: A User's Guide to a New Technique for Biological and Biomedical Research. © 2012 Elsevier B.V.

Price C.A.,University of Montreal
Journal of Endocrinology | Year: 2016

Fibroblast growth factors (FGFs) have been shown to alter growth and differentiation of reproductive tissues in a variety of species. Within the female reproductive tract, the effects of FGFs have been focused on the ovary, and the most studied one is FGF2, which stimulates granulosa cell proliferation and decreases differentiation (decreased steroidogenesis). Other FGFs have also been implicated in ovarian function, and this review summarizes the effects of members of two subfamilies on ovarian function; the FGF7 subfamily that also contains FGF10, and the FGF8 subfamily that also contains FGF18. There are data to suggest that FGF8 and FGF18 have distinct actions on granulosa cells, despite their apparent similar receptor binding properties. Studies of non-reproductive developmental biology also indicate that FGF8 is distinct from FGF18, and that FGF7 is also distinct from FGF10 despite similar receptor binding properties. In this review, the potential mechanisms of differential action of FGF7/FGF10 and FGF8/FGF18 during organogenesis will be reviewed and placed in the context of follicle development. A model is proposed in which FGF8 and FGF18 differentially activate receptors depending on the properties of the extracellular matrix in the follicle. © 2016 Society for Endocrinology.

Picard M.,McGill University | Hepple R.T.,McGill University | Burelle Y.,University of Montreal
American Journal of Physiology - Cell Physiology | Year: 2012

In skeletal muscle, two major types of muscle fibers exist: slow-twitch oxidative (type I) fibers designed for low-intensity long-lasting contractions, and fast-twitch glycolytic (type II) fibers designed for high-intensity short-duration contractions. Such a wide range of capabilities has emerged through the selection across fiber types of a narrow set of molecular characteristics suitable to achieve a specific contractile phenotype. In this article we review evidence supporting the existence of distinct functional phenotypes in mitochondria from slow and fast fibers that may be required to ensure optimal muscle function. This includes differences with respect to energy substrate preferences, regulation of oxidative phosphorylation, dynamics of reactive oxygen species, handling of Ca 2+, and regulation of cell death. The potential physiological implications on muscle function and the putative mechanisms responsible for establishing and maintaining distinct mitochondrial phenotype across fiber types are also discussed. © 2012 the American Physiological Society.

Roy G.,University of Montreal
Seminars in Reproductive Medicine | Year: 2010

Injectable contraception has many advantages and is a popular birth control method worldwide. Its efficacy is independent of a daily action or an intervention around the time of coitus. It is highly efficacious and well tolerated in general. In the United States, the available injectable contraceptive is depot medroxyprogesterone acetate (DMPA). Its use is associated with a decrease in bone mineral density (BMD) that is largely if not completely reversible over time and very comparable to the BMD loss associated with pregnancy and breastfeeding. The available knowledge on the impact of BMD loss on the risks of fractures later in life is incomplete, but in the light of the small magnitude of impact of DMPA on BMD and its reversibility, any increase in the risk of osteoporotic fractures is likely to be small. This article reviews the recent evidence on DMPA's efficacy, risks and benefits, and side effects with a focus on bone health issues. © 2010 by Thieme Medical Publishers, Inc.

Ashton-Beaucage D.,University of Montreal
Fly | Year: 2011

Alternative splicing provides one of the major mechanisms by which eukaryotic genomes can increase the diversity of transcripts and protein products encoded by a limited amount of genes. The spliceosome is involved in recognizing and removing intronic sequences and it is guided in this activity by splicing regulatory factors that determine the particular splice sites that are to be recognized and used for intron removal. Thus, by modulating the spliceosome's activity, these factors can cause different mRNA transcripts to be generated from the same precursor mRNA. In a recent RNAi screen for factors modulating RAS/MAPK signaling, we identified the Drosophila exon junction complex (EJC) as one of the components regulating the splicing of mapk transcripts. We showed that removal of EJC components caused multiple consecutive mapk exons to be skipped. Moreover, we determined that other fly genes that, like mapk, had particularly large introns, were also sensitive to disruption of the EJC. The importance of intron length in determining sensitivity to EJC disruption suggests that the EJC is functioning in exon definition, a splicing mechanism that occurs for long introns in particular.

Cruite I.,University of Washington | Tang A.,University of Montreal | Sirlin C.B.,University of California at San Diego
American Journal of Roentgenology | Year: 2013

OBJECTIVE. Noninvasive imaging plays critical roles in the treatment of patients with cirrhosis or other risk factors for the development of hepatocellular carcinoma. In recognition of the critical roles played by imaging, numerous international scientific organizations and societies have, in the past 12 years, proposed diagnostic systems for the interpretation of liver imaging examinations performed of at-risk patients. CONCLUSION. Although these imaging-based diagnostic systems represent important advances, they have limitations and they are not perfectly consistent with each other. The limitations and inconsistencies potentially cause confusion and may impair the integration of the systems into clinical practice as well as their utilization in research studies. The purpose of this article is to synthesize and critically appraise the current published imaging-based diagnostic systems endorsed by major societies for the noninvasive diagnosis and staging of hepatocellular carcinoma and to propose future directions that we hope may be helpful in further advancing the field. © American Roentgen Ray Society.

Beauchamp G.,University of Montreal
Biology Letters | Year: 2010

Disentangling the relative contribution of predation avoidance and increased foraging efficiency in the evolution of sociality in animals has proven difficult given that the two types of benefits often operate concurrently. I identified different types of refuges from predation in birds related to morphological and ecological traits, providing an opportunity to examine concomitant changes in sociality over evolutionary times. Results of a matched-species comparative analysis indicated a reduction in the size of foraging or non-foraging groups but not complete disappearance under negligible predation risk. The results suggest that while predation avoidance is an important component in the evolution of sociality in birds, it is most probably not acting alone but rather in conjunction with other benefits such as increased foraging efficiency. © 2010 The Royal Society.

Parrott L.,University of Montreal | Meyer W.S.,University of Adelaide
Frontiers in Ecology and the Environment | Year: 2012

A regional landscape is a complex social-ecological system comprising a dynamic mosaic of land uses. Management at this scale requires an understanding of the myriad interacting human and natural processes operating on the landscape over a continuum of spatial and temporal scales. Complexity science, which is not part of traditional management approaches, provides a valuable conceptual framework and quantitative tools for dealing with cross-scale interactions and non-linear dynamics in social-ecological systems. Here, we identify concepts and actions arising from complexity science that can be learned and applied by ecosystem managers and discuss how they might be implemented to achieve sustainable future landscapes. © The Ecological Society of America.

BACKGROUND: Studies of trends in population changes and epidemiological profiles in the developing world have overwhelmingly relied upon the concepts of demographic, epidemiological, and health transitions, even though their usefulness in describing and understanding population and health trends in developing countries has been repeatedly called into question. The issue is particularly relevant for the study of population health patterns in Africa and sub-Saharan Africa, as the history and experience there differs substantially from that of Western Europe and North America, for which these concepts were originally developed.OBJECTIVE: The aim of this study is two-fold: to review and clarify any distinction between the concepts of demographic transition, epidemiological transition and health transition and to identify summary indicators of population health to test how well these concepts apply in Africa.RESULTS: Notwithstanding the characteristically diverse African context, Africa is a continent of uncertainties and emergencies where discontinuities and interruptions of health, disease, and mortality trends reflect the enduring fragility and instability of countries and the vulnerabilities of individuals and populations in the continent. Africa as a whole remains the furthest behind the world's regions in terms of health improvements and longevity, as do its sub-Saharan African regions and societies specifically. This study documents: 1) theoretically and empirically the similarities and differences between the demographic transition, epidemiological transition, and health transition; 2) simple summary indicators that can be used to evaluate their descriptive and predictive features; 3) marked disparities in the onset and pace of variations and divergent trends in health, disease, and mortality patterns as well as fertility and life expectancy trajectories among African countries and regions over the past 60 years; 4) the rapid decline in infant mortality and gains in life expectancy from the 1950s through the 1990s in a context of preponderant communicable diseases in all African countries; 5) the salient role of adult mortality, mostly ascribed to HIV/AIDS and co-morbidities, since the 1990s in reversing trends in mortality decline, its interruption of life expectancy improvements, and its reversal of gender differences in life expectancies disadvantaging women in several countries with the highest prevalence of HIV/AIDS; 6) the huge impact of wars in reversing the trends in under-five mortality decline in sub-Saharan countries in the 1990s and beyond. These assessments of these transition frameworks and these phenomena were not well documented to date for all five regions and 57 countries of Africa.CONCLUSION: Prevailing frameworks of demographic, epidemiological, and health transitions as descriptive and predictive models are incomplete or irrelevant for charting the population and health experiences and prospects of national populations in the African context.

Delisle H.,University of Montreal
The British journal of nutrition | Year: 2012

A rising prevalence of CVD and diabetes has been observed in sub-Saharan Africa, particularly in cities. The aim of the present study conducted in Benin was to examine the mediating role of nutrition transition in the relationship of urbanisation level and socio-economic status (SES) to cardiometabolic risk markers. A total of 541 subjects in apparent good health were randomly selected from the main city of Cotonou, a small town and its surrounding rural areas. SES was assessed based on a proxy for income and on education. Dietary intake and physical activity were assessed with at least two non-consecutive 24 h recalls. Scores for micronutrient adequacy and preventive diet were used as indicators of diet quality. Cardiometabolic risk markers were BMI, waist circumference (WC), blood pressure, serum cholesterol and insulin resistance according to homeostasis model assessment. A more advanced stage of nutrition transition, which correlated with lower diet quality scores and less physical activity, was observed in the large city compared with less urbanised locations. More obesity and more adverse cholesterol profiles, but also lower blood pressure, were present in the large city. Urbanisation, income, sedentary lifestyle and alcohol consumption, but not diet quality, independently contributed to higher BMI and WC. Higher micronutrient adequacy was independently associated with a better cholesterol profile. The study confirmed the positive rural-urban gradient in nutrition transition and cardiometabolic risk, except for blood pressure. This risk could be mitigated by a more adequate diet, particularly micronutrient intake, and a more active lifestyle.

Hanessian S.,University of Montreal
Journal of Organic Chemistry | Year: 2012

A retrospective account of natural products synthesis adopting the Chiral Synthon (Chiron) Approach and spanning nearly 50 years of personal research activity is presented highlighting the interplay between the eye and the mind's eye. Synthesis planning is discussed in terms of visual relational and visual reflexive thinking modalities relying on the recognition of naturally occurring nonracemic starting materials such as amino acids, carbohydrates, hydroxy acids, and terpenes in the carbon framework of target molecules. Lessons learned and synthetic methods developed are discussed in the context of selected natural products covered in this Perspective. © 2012 American Chemical Society.

Nielsen T.,University of Montreal
Journal of Biological Rhythms | Year: 2010

Relations between common nightmares and chronobiological factors remain poorly understood. The possibility that nightmare frequency and distress are associated with chronotype ("morningness-eveningness") was investigated in a sample of respondents to an Internet questionnaire. Over a 41/2-year period, a total of 3978 subjects (mean age = 26.5 ± 11.6 yrs; age range = 10-69; 2933 female, 1045 male) submitted responses to single items about chronotype and nightmares as well as to other demographic variables. Analyses of chronotype and nightmares items by age and gender replicated most previous findings for these measures-validating their further assessment-and uncovered abrupt increases in nightmare distress between ages 10-19 and 20-29 for females and ages 30-39 and 40-49 for males. Most important, there was a strong association between nightmares and eveningness for female subjects. The latter was expressed as a linear association between nightmare frequency and increasing eveningness and a cubic association between nightmare distress and increasing eveningness; the definite evening types displayed the most severe nightmares. The effect for nightmare frequency was independent of age and sleep duration but was eliminated when nightmare distress was covaried. For females, the nightmare/eveningness association appeared at ages 20 to 29 for the definite evening type and only later, at ages 30 to 39, for the moderate evening type. Findings are consistent with the possibility that nightmares are the expression of a more general pathological factor that is characteristic of eveningness and that is responsible for affective symptoms such as neuroticism and depression. This pathological factor appears to be expressed in late adolescence/ early adulthood, and relative morningness may be a protective factor delaying its onset. The well-established circadian modulations of cognitive, social, and affective tasks that are influenced by chronotype may extend to the memory and affective processes of sleep-including dreaming. This chronotypic influence, together with a likely gender difference in the neurophysiological substrate of emotional processing, may result in the differential occurrence of nightmares for female evening types. © 2010 SAGE Publications.

Pabayo R.,University of Montreal
Social science & medicine (1982) | Year: 2011

In light of geographical and epidemiological research suggesting that the socioeconomic environment beyond the family may influence children's physical activity, this study investigated the extent to which neighbourhood socioeconomic conditions predict change in physical activity from ages 10 through 15 years, controlling for the attributes of the individual child and family. Data came from 889 children participating in the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development cohort study. Accelerometers measured Moderate-to-Vigorous Physical Activity (MVPA) during the week and weekend, when the children were aged 10, 11, and 15 years. Selected US census block variables were used to create 'independent' area measures of economic deprivation and social fragmentation scores for child's area of residence at age 10 years. Also, parents' perception of neighbourhood social cohesion was measured in terms of relationships with neighbours. All analyses controlled for participant characteristics: gender, ethnicity, household income-to-needs ratio, maternal education, and for United States region of residence. Growth curve analyses indicated that whereas social fragmentation did not predict MVPA over time, greater area deprivation at age 10 years was associated with lower weekday MVPA for boys at 10 years (β=-0.5, p=0.03) and these differences persisted to age 11 and 15 years. This relationship was reversed for girls. Weekend MVPA was not significantly associated with the level of deprivation in the place of residence at age 10 years. Although the census measure of social fragmentation in the area of residence showed no significant association with MVPA, parent-reported neighbourhood social cohesion was positively associated with weekday (β=2.0, p<0.01) and weekend (β=3.1, p<0.01) MVPA minutes across time. This association was most pronounced for boys. Area level factors may be determinants of physical activity among children and youth in complex ways and parental perception of area social environment may be as important for children's activity levels as 'independently assessed' socioeconomic conditions. Copyright © 2010 Elsevier Ltd. All rights reserved.

Lettre G.,Montreal Heart Institute | Lettre G.,University of Montreal
Human Genetics | Year: 2011

Adult height is a classic polygenic trait of high narrow-sense heritability (h2 = 0.8). In the late nineteenth to early twentieth century, variation in adult height was used as a model to set the foundation of the fields of statistics and quantitative genetics. More recently, with our increasing knowledge concerning the extent of genetic variation in the human genome, human geneticists have used genome-wide association studies to identify hundreds of loci robustly associated with adult height, providing new insights into human growth and development, and into the architecture of complex human traits. In this review, I highlight the progress made in the last 2 years in understanding how genetic variation controls height variation in humans, including non-Caucasian populations and children. © 2011 Springer-Verlag.

Shapiro B.J.,University of Montreal | Polz M.F.,Massachusetts Institute of Technology
Trends in Microbiology | Year: 2014

We propose that microbial diversity must be viewed in light of gene flow and selection, which define units of genetic similarity, and of phenotype and ecological function, respectively. We discuss to what extent ecological and genetic units overlap to form cohesive populations in the wild, based on recent evolutionary modeling and on evidence from some of the first microbial populations studied with genomics. These show that if recombination is frequent and selection moderate, ecologically adaptive mutations or genes can spread within populations independently of their original genomic background (gene-specific sweeps). Alternatively, if the effect of recombination is smaller than selection, genome-wide selective sweeps should occur. In both cases, however, distinct units of overlapping ecological and genotypic similarity will form if microgeographic separation, likely involving ecological tradeoffs, induces barriers to gene flow. These predictions are supported by (meta)genomic data, which suggest that a 'reverse ecology' approach, in which genomic and gene flow information is used to make predictions about the nature of ecological units, is a powerful approach to ordering microbial diversity. © 2014 Elsevier Ltd.

Goriely S.,Free University of Colombia | Chamel N.,Free University of Colombia | Pearson J.M.,University of Montreal
Physical Review C - Nuclear Physics | Year: 2013

Our family of three Hartree-Fock-Bogoliubov (HFB) mass models, labeled BSk19, BSk20, and BSk21, is here extended by (a) refitting to the 2012 Atomic Mass Evaluation (AME), and (b) varying the symmetry coefficient J. Five new models, labeled BSk22 to BSk26, along with their mass tables, HFB-22 to HFB-26, respectively, are presented. These models are characterized by unconventional Skyrme forces containing t4 and t5 terms, i.e., density-dependent generalizations of the usual t1 and t2 terms, respectively. Highly realistic contact pairing forces are used. The Skyrme forces are constrained to fit realistic equations of state of neutron matter stiff enough to support the massive neutron stars PSR J1614-2230 and PSR J0348+0432. Unphysical spin and spin-isospin instabilities of homogeneous nuclear matter, including the transition to a polarized state in neutron-star matter, are eliminated with the new forces. The best fits to the new database of 2353 nuclei are found for models BSk24 (J=30 MeV) and BSk25 (J=29 MeV), for which the root-mean square (rms) deviations are 0.55 and 0.54 MeV, respectively. Despite the larger database this is even better than the rms deviation of 0.58 MeV that we found with our fits to the 2003 AME. With J=32 MeV the rms deviation rises to 0.63 MeV. The neutron-skin thicknesses derived from antiproton scattering are shown to be consistent with the conclusions that we have drawn from masses. © 2013 American Physical Society.

Rota-Stabelli O.,National University of Ireland, Maynooth | Rota-Stabelli O.,Research and Innovation Center | Lartillot N.,University of Montreal | Philippe H.,University of Bristol | And 2 more authors.
Systematic Biology | Year: 2013

Phylogenomic analyses of ancient relationships are usually performed using amino acid data, but it is unclear whether amino acids or nucleotides should be preferred. With the 2-fold aim of addressing this problem and clarifying pancrustacean relationships, we explored the signals in the 62 protein-coding genes carefully assembled by Regier et al. in 2010. With reference to the pancrustaceans, this data set infers a highly supported nucleotide tree that is substantially different to the corresponding, but poorly supported, amino acid one. We show that the discrepancy between the nucleotide-based and the amino acids-based trees is caused by substitutions within synonymous codon families (especially those of serine-TCN and AGY). We show that different arthropod lineages are differentially biased in their usage of serine, arginine, and leucine synonymous codons, and that the serine bias is correlated with the topology derived from the nucleotides, but not the amino acids. We suggest that a parallel, partially compositionally driven, synonymous codon-usage bias affects the nucleotide topology. As substitutions between serine codon families can proceed through threonine or cysteine intermediates, amino acid data sets might also be affected by the serine codon-usage bias. We suggest that a Dayhoff recoding strategy would partially ameliorate the effects of such bias. Although amino acids provide an alternative hypothesis of pancrustacean relationships, neither the nucleotides nor the amino acids version of this data set seems to bring enough genuine phylogenetic information to robustly resolve the relationships within group, which should still be considered unresolved. © 2012 The Author(s).

Infantile spasms (IS) are a unique and severe form of epilepsy associated with poor neurologic and developmental outcomes. The refractory spasms and abnormal electroencephalogram (EEG) patterns associated with the condition are believed to have a progressively detrimental impact. Therefore, rapid and complete control of spasms is the primary goal of treatment. Well-controlled clinical trials in Europe, Canada, and the United States have demonstrated that vigabatrin is efficacious and generally well-tolerated as monotherapy for IS. Several key studies, including pivotal trials that led to United States approval of vigabatrin in 2009, as well as comparative trials of vigabatrin and hormonal treatment, are the focus of this review. All studies assessed spasm cessation - usually as the primary endpoint - and adverse events. Vigabatrin dosages generally ranging from 100 to 150mg/kg/day demonstrated efficacy to decrease or eradicate spasms and eliminate hypsarrhythmic EEG in patients with newly diagnosed IS. Several studies demonstrated long-term sustainability of spasm freedom with no negative impact on developmental outcomes. Vigabatrin was generally well-tolerated with few severe adverse events. Visual field defects cannot be adequately assessed in infants and young children, so this potential adverse effect was not evaluated in children with spasms. Notably, the time to response with vigabatrin was very rapid, generally occurring within 2weeks of initial treatment. This allows for early treatment modification as needed. For infants who respond well to vigabatrin, treatment duration up to 6months appears to be appropriate for realizing spasm freedom while limiting potential risks of adverse events and recurrences. © 2011 John Wiley & Sons A/S.

Bertola M.,University of Montreal | Cafasso M.,Concordia University at Montreal
Physica D: Nonlinear Phenomena | Year: 2012

We prove that matrix Fredholm determinants related to multi-time processes can be expressed in terms of determinants of integrable kernels à la Its-Izergin-Korepin-Slavnov (IIKS) and hence related to suitable Riemann-Hilbert problems, thus extending the known results for the single-time case. We focus on the Airy and Pearcey processes. As an example of applications we re-deduce a third order PDE, found by Adler and van Moerbeke, for the two-time Airy process. © 2011 Elsevier B.V. All rights reserved.

Rixen T.,University of Montreal
Global Governance | Year: 2011

This article presents the normative case for global tax governance. Contrary to an influential part of the literature, national tax policy choices cause significant externalities for other nation-states. Focusing on business taxation, the article shows that tax competition undermines the integrity and distributive principles of domestic tax systems and aggravates the inequality between developed and developing countries. Further, it demonstrates that the effects of international tax competition are unjust irrespective of whether a globalist or less demanding internationalist perspective on justice is adopted. The minimum requirement of justice is to devise global rules that ensure that national tax systems remain capable of implementing distributive justice as they see fit. Finally, the article presents and discusses a concrete proposal for the global governance of business tax competition, namely, unitary taxation with formula apportionment.

Montpetit E.,University of Montreal
Policy Studies Journal | Year: 2011

One of the original objectives of the advocacy coalition framework (ACF) was to shed light on the role of science in policymaking. The ACF depicts subsystem scientists as political actors just like any other. Unfortunately, science has never become a major theme of research within the framework and, as a consequence, its role in policymaking remains under-theorized, leaving ample room for interpretation. This article seeks to explore the validity of three propositions about the role of science in policy. The first two are derived from the ACF: (i) the capacity of scientists to provide credible advice is affected by the harshness of the political debates dividing the policy subsystem; and (ii) agreement among scientists is just as common as among other groupings of policy actors. The third is derived from an "error costs" argument: (iii) Disagreements among scientists are even more pronounced than disagreements among other policy actors. Using the results of a survey of policy actors in 17 biotechnology subsystems, this article finds support for the first and third propositions. Indeed, scientists' participation in political divisions might even be underestimated by the ACF. The article concludes with attempts to clarify the role of scientists within the ACF, including discussions of ambiguity regarding the role of professional forums and of scientists in between-coalition learning within policy subsystems. © 2011 Policy Studies Organization.

Domon G.,University of Montreal
Landscape and Urban Planning | Year: 2011

While the economy of rural areas has always been strongly dependent on natural resource exploitation, recent technological advancements in exploitation, loss of rural livelihood, and increased social demand for the amenity aspects of these resources have dramatically changed rural economies. The result of these interrelated phenomena is such that the configuration of rural landscapes is literally being re-drawn, and areas rich in amenities such as visual quality are the object of strong development pressures while " ordinary" landscapes are threatened with a new kind of devitalization. This paper describes how these phenomena challenge landscape designers, planners, and researchers at methodological and heuristic as well as ethical levels, and place them in a privileged role of great responsibility in guiding the future of the rural landscape. © 2011 Elsevier B.V.

Metnani A.,University of Montreal | Jaumard B.,Concordia University at Montreal
IEEE/ACM Transactions on Networking | Year: 2013

Application opportunities associated with video, voice, and data triple-play result in a dramatic demand increase in metro transport networks, with traffic patterns becoming increasingly dynamic and difficult to predict. This is driving the need of core networks with a high degree of flexibility and multigranularities to carry traffic. We propose to investigate the question of what this means in terms of dynamic protection provisioning. In other words, we want to study how stable are the protection structures under dynamic traffic, i.e., how much and how often they need to be updated in a dynamic survivable WDM network. While most studies on the stability of protection structures have been conducted on p-cycles and link shared protection, we propose to investigate here the stability of failure-independent path-protecting (FIPP) p-cycles under dynamic traffic. For doing so, we design and develop an original scalable mathematical model that we solve using large-scale optimization tools. Numerical results show that FIPP p-cycles are remarkably stable under the evaluation of the number of required optical bypass reconfigurations under dynamic traffic. © 1993-2012 IEEE.

Theoret C.L.,University of Montreal | Wilmink J.M.,Woumarec
Wound Repair and Regeneration | Year: 2013

Impaired wound healing represents an enormous clinical and financial problem for companion animals and humans alike. Unfortunately, most models used to study healing rely on rodents, which have significant differences in the healing and scarring process and rarely develop complications. In order to better simulate impaired healing, the model should strive to reproduce the natural processes of healing and delayed healing. Wounds on the limbs of horses display similarities to wounds in humans in their epithelialization/contraction ratio, genetic influence as well as dysregulated cytokine profile and the spontaneous development of fibroproliferative disorders. Veterinarians have access to advanced wound therapies that are often identical to those provided to human patients. Wound research in large animals has resulted in new wound models as well as a better understanding of the physiology, immunology, and local environmental impact on both normal and aberrant wound healing. One such model reproduces the naturally occurring fibroproliferative disorder of horses known as exuberant granulation tissue. Comparisons between the normally healing and impaired wounds provide insight into the repair process and can facilitate product development. A better understanding of the wound healing physiopathology based on clinically accurate animal models should lead to the development of novel therapies thereby improving outcomes in both human and veterinary patients. © 2013 by the Wound Healing Society.

Lizarralde G.,University of Montreal
Habitat International | Year: 2011

Subsidized housing projects in developing countries are constrained by important challenges. Up-front subsidies are often insufficient to solve the housing needs of beneficiaries and subsidized units are considered too small. However, the delivery of 'finished' units might be neither necessary nor desirable. The qualitative examination of two subsidized housing projects in Colombia and South Africa shows how the challenges related with the size and quality of the units can be efficiently faced adopting an approach based on incremental growth of housing units. In South Africa, the project emphasized the participation of beneficiaries from construction to occupation, while in Colombia the project assumed an incremental housing approach. In the Colombian case, beneficiaries were not early involved in construction activities, but instead, the project anticipated user-driven additions and upgrading, recognizing the role of beneficiaries during the post-occupancy phase. The comparison of the two projects shows the advantages of optimizing the investment of up-front subsidies in an incremental construction. It also highlights that the size and quality of units depend, in reality, on early decisions made during the planning and design of the project, which have a considerable influence on the participation of stakeholders during the post-occupancy phase. Even though much attention is often given to the participation of beneficiaries during project construction, the results suggest that the success of a subsidized housing project is strongly related with the appropriate coordination of formal and informal stakeholders after the occupation of units. © 2010 Elsevier Ltd.

Lartillot N.,University of Montreal | Lartillot N.,Montpellier University
Molecular Biology and Evolution | Year: 2013

GC-biased gene conversion (gBGC) is a major evolutionary force shaping genomic nucleotide landscapes, distorting the estimation of the strength of selection, and having potentially deleterious effects on genome-wide fitness. Yet, a global quantitative picture, at large evolutionary scale, of the relative strength of gBGC compared with selection and random drift is still lacking. Furthermore, owing to its dependence on the local recombination rate, gBGC results in modulations of the substitution patterns along genomes and across time which, if correctly interpreted, may yield quantitative insights into the long-term evolutionary dynamics of recombination landscapes. Deriving a model of the substitution process at putatively neutral nucleotide positions from population-genetics arguments, and accounting for among-lineage and among-gene effects, we propose a reconstruction of the variation in gBGC intensity at the scale of placental mammals, and of its scaling with body-size and karyotypic traits. Our results are compatible with a simple population genetics model relating gBGC to effective population size and recombination rate. In addition, among-gene variation and phylogenetic patterns of exon-specific levels of gBGC reveal the presence of rugged recombination landscapes, and suggest that short-lived recombination hot-spots are a general feature of placentals. Across placental mammals, variation in gBGC strength spans two orders of magnitude, at its lowest in apes, strongest in lagomorphs, microbats or tenrecs, and near or above the nearly neutral threshold in most other lineages. Combined with among-gene variation, such high levels of biased gene conversion are likely to significantly impact midly selected positions, and to represent a substantial mutation load. Altogether, our analysis suggests a more important role of gBGC in placental genome evolution, compared with what could have been anticipated from studies conducted in anthropoid primates. © 2012 The Author.

Legendre P.,University of Montreal
Global Ecology and Biogeography | Year: 2014

Aim: The variation in species composition among sites, or beta diversity, can be decomposed into replacement and richness difference. A debate is ongoing in the literature concerning the best ways of computing and interpreting these indices. This paper first reviews the historical development of the formulae for decomposing dissimilarities into replacement, richness difference and nestedness indices. These formulae are presented for species presence-absence and abundance using a unified algebraic framework. The indices decomposing beta play different roles in ecological analysis than do beta-diversity indices. Innovation: Replacement and richness difference indices can be interpreted and related to ecosystem processes. The pairwise index values can be summed across all pairs of sites; these sums form a valid decomposition of total beta diversity into total replacement and total richness difference components. Different communities and study areas can be compared: some may be dominated by replacement, others by richness/abundance difference processes. Within a region, differences among sites measured by these indices can then be analysed and interpreted using explanatory variables or experimental factors. The paper also shows that local contributions of replacement and richness difference to total beta diversity can be computed and mapped. A case study is presented involving fish communities along a river. Main conclusions: The different forms of indices are based upon the same functional numerators. These indices are complementary; they can help researchers understand different aspects of ecosystem functioning. The methods of analysis used in this paper apply to any of the indices recently proposed. Further work, based on ecological theory and numerical simulations, is required to clarify the precise meaning and domain of application of the different forms. The forms available for presence-absence and quantitative data are both useful because these different data types allow researchers to answer different types of ecological or biogeographic questions. © 2014 John Wiley & Sons Ltd.

Baron C.,University of Montreal
Current Opinion in Microbiology | Year: 2010

The rise of resistance of pathogenic bacteria to antibiotics constitutes an increasing risk to public health. Environmental bacteria constitute a large reservoir of resistance determinants and it is predictable that resistance to more antibiotics will be acquired by even more pathogens in future. Innovative strategies are therefore needed to discover novel antibiotic targets as well as alternatives to classical antibiotics. This review will discuss recent advances toward the development of an alternative to classical antibiotics, antivirulence drugs targeting bacterial secretion systems that would disarm rather than kill bacteria. Important progress has been made especially targeting type III secretion systems that are used by many different Gram-negative pathogens. Antivirulence drugs that disarm bacterial pathogens have the potential to be an important alternative or addition to classical antibiotics in future. © 2009 Elsevier Ltd. All rights reserved.

Lefebvre H.,University of Montreal
Journal of trauma nursing : the official journal of the Society of Trauma Nurses | Year: 2012

Traumatic brain injury (TBI) is an important public health concern that presents real challenges for health care systems throughout the world. Through an international partnership between Canadian and French researchers, a vast qualitative study aimed to explore the needs of individuals with TBIs and their loved ones throughout the continuum of care and services. The study was first conducted in 3 regions of Quebec (Canada) and subsequently replicated in 3 regions of France. Overall, the data were collected from focus groups with 150 participants: individuals with TBIs, their loved ones, and health care professionals. Despite regional differences, the results demonstrate participants' very similar perceptions regarding the needs such as information, support, and a collaborative relationship with health care professionals experienced by individuals with TBIs and their loved ones. These needs change throughout the stages of care. The fulfillment of these needs play a determining role throughout the adaptation process of individuals with TBIs and their loved ones. Health care professionals must adopt a personalized approach to respond to needs related to the evolution of information, support, and relationships.

Tannenbaum C.,University of Montreal
American journal of men's health | Year: 2011

Masculinity is a social construction that defines itself according to context. Older men constitute an unseen minority when it comes to their health, and thus the study of masculinity as it relates to health in older men requires deeper understanding. This article offers insights into how gender, health, and ageing interact for older men and explores how men negotiate the concept of masculinity in later life. The findings from two complementary studies are presented and discussed. The first study, a qualitative analysis of focus group discussions held with 48 community-dwelling older men, indicates that the desire to uphold hegemonic ideals of independence, self-reliance, and imperviousness to pain and illness are embedded in older men's health-related beliefs and behaviors. Ill health and help seeking are often perceived as a threat to the masculine identity, and taking action for health is considered only when health status jeopardizes independence. In the second study, more than 2,000 men aged 55 to 97 years responded to a postal survey on health behaviors and masculinity. Results of the survey indicated that age predicts health behaviors and health care seeking better than scores on a masculinity index, which tended to remain stable regardless of age. Both the qualitative and quantitative findings support the hypothesis that with age men will succeed in incorporating actions into their daily lives in a way that does not conflict with their perceived resilience to frailty and weakness, even if such actions involve seeking help for illness or adopting healthier lifestyle behaviors.

Lee J.,University of California at Los Angeles | Gosselin F.,University of Montreal | Wynn J.K.,University of California at Los Angeles | Green M.F.,University of California at Los Angeles
Schizophrenia Bulletin | Year: 2011

Impairment in recognizing facial emotions is a prominent feature of schizophrenia patients, but the underlying mechanism of this impairment remains unclear. This study investigated the specific aspects of visual information that are critical for schizophrenia patients to recognize emotional expression. Using the Bubbles technique, we probed the use of visual information during a facial emotion discrimination task (fear vs. happy) in 21 schizophrenia patients and 17 healthy controls. Visual information was sampled through randomly located Gaussian apertures (or "bubbles") at 5 spatial frequency scales. Online calibration of the amount of face exposed through bubbles was used to ensure 75% overall accuracy for each subject. Least-square multiple linear regression analyses between sampled information and accuracy were performed to identify critical visual information that was used to identify emotional expression. To accurately identify emotional expression, schizophrenia patients required more exposure of facial areas (i.e., more bubbles) compared with healthy controls. To identify fearful faces, schizophrenia patients relied less on bilateral eye regions at high-spatial frequency compared with healthy controls. For identification of happy faces, schizophrenia patients relied on the mouth and eye regions; healthy controls did not utilize eyes and used the mouth much less than patients did. Schizophrenia patients needed more facial information to recognize emotional expression of faces. In addition, patients differed from controls in their use of high-spatial frequency information from eye regions to identify fearful faces. This study provides direct evidence that schizophrenia patients employ an atypical strategy of using visual information to recognize emotional faces. © 2011 The Author.

Lafreniere D.,University of Montreal | Lafreniere D.,University of Toronto | Jayawardhana R.,University of Toronto | Van Kerkwijk M.H.,University of Toronto
Astrophysical Journal | Year: 2010

Giant planets are usually thought to form within a few tens of AU of their host stars, and hence it came as a surprise when we found what appeared to be a planetary mass (∼0.008M⊙) companion around the 5 Myr old solar mass star 1RXS J160929.1-210524 in the Upper Scorpius association. At the time, we took the object's membership in Upper Scorpius-established from near-infrared, H- and K-band spectroscopy-and its proximity (2.″2 or 330 AU) to the primary as strong evidence for companionship, but could not verify their common proper motion. Here, we present follow-up astrometric measurements that confirm that the companion is indeed commoving with the primary star, which we interpret as evidence that it is a truly bound planetary mass companion. We also present new J-band spectroscopy and 3.0-3.8 μm photometry of the companion. Based on a comparison with model spectra, these new measurements are consistent with the previous estimate of the companion effective temperature of 1800 ± 200 K. We present a new estimate of the companion mass based on evolution models and the calculated bolometric luminosity of the companion; we obtain a value of 0.008+0.003 -0.002M⊙, again consistent with our previous result. Finally, we present angular differential imaging observations of the system allowing us to rule out additional planets in the system more massive than 1 M Jup, 2 MJup, and 8 MJup at projected separations larger than 3″ (∼440 AU), 0. ″7 (∼100 AU), and 0. ″35 (∼50 AU), respectively. This companion is the least massive known to date at such a large orbital distance; it shows that objects in the planetary mass range exist at orbital separations of several hundred AU, posing a serious challenge for current formation models. © 2010. The American Astronomical Society. All rights reserved.

Daniel Dubreuil J.,University of Montreal
Critical Reviews in Microbiology | Year: 2010

Escherichia coli enterotoxigenic strains produce one or more toxins which action result in production of diarrhea in animals including Man. One of these toxins, STb, has been mainly associated with colibacillosis in swine. Although highly prevalent in pigs with diarrhea, a relation between STb and disease was arduous to establish. With the recent recognition of a new adhesin, originally found in human E. coli isolates, named AIDA (adhesin involved in diffuse adherence) and its association with new E. coli pathotypes to which STb is linked, new light was shed on STb toxic potency. In this review, the association of STb and AIDA is examined according to the recent knowledge gained with newly described E. coli pathotypes. © 2010 Informa UK Ltd.

Mukaddam-Daher S.,University of Montreal
Canadian Journal of Cardiology | Year: 2012

The centrally-acting sympatholytic imidazoline compound, moxonidine, prevents the development of left ventricular hypertrophy and attenuates maladaptive proliferative signalling as well as downstream apoptotic pathways in spontaneously hypertensive rat and cardiomyopathic hamster hearts. The actions are selectively mediated by imidazoline type-1 receptor (I1-receptor, also named nischarin), nonadrenergic neurotransmitter receptors mainly found in the brainstem medulla. We identified cardiac I1-receptors/nischarin and showed that they are upregulated in cardiovascular disorders, and are functional without the central nervous system's contribution. Molecular characterization revealed that I1-receptor/nischarin has a unique structure with multifunctional domains allowing it to perform a number of cell signalling roles as a scaffolding protein. Nischarin has been associated with integrin α5 and inhibition of Rac1 and was shown to interact with insulin receptor substrates. However, very little is known about cardiac I1-receptor/nischarin and its role(s) in normal physiology and pathophysiology, specifically in cardiac remodelling. Our studies have shown that I1-receptor is expressed in cardiac fibroblasts and myocytes and that in vitro I1-receptor activation inhibits norepinephrine-induced cardiomyocyte apoptosis and fibroblast proliferation, through differential effects on mitogen-activated protein kinases and Akt. Accordingly, apart from centrally-mediated sympatholytic function, I1-receptor in the heart may control cell growth and death. I1-receptor may be implicated in cardiac remodelling and dysfunction, through the inhibition of apoptotic pathways and/or activation of survival pathways, in a cell-specific manner. Identification of the cardioprotective mechanisms of cardiac I1-receptor could result in specifically-tailored cell/gene-driven I1-receptor treatments, and/or treatments that target cardiac I1-receptor, which could eventually be important for patients with hypertrophic heart disease. © 2012 Canadian Cardiovascular Society.

Labelle H.,University of Montreal
European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society | Year: 2011

In L5-S1 spondylolisthesis, it has been clearly demonstrated over the past decade that sacro-pelvic morphology is abnormal and that it can be associated to an abnormal sacro-pelvic orientation as well as to a disturbed global sagittal balance of the spine. The purpose of this article is to review the work done within the Spinal Deformity Study Group (SDSG) over the past decade, which has led to a classification incorporating this recent knowledge. The evidence presented has been derived from the analysis of the SDSG database, a multi-center radiological database of patients with L5-S1 spondylolisthesis, collected from 43 spine surgeons in North America and Europe. The classification defines 6 types of spondylolisthesis based on features that can be assessed on sagittal radiographs of the spine and pelvis: (1) grade of slip, (2) pelvic incidence, and (3) spino-pelvic alignment. A reliability study has demonstrated substantial intra- and inter-observer reliability similar to other currently used classifications for spinal deformity. Furthermore, health-related quality of life measures were found to be significantly different between the 6 types, thus supporting the value of a classification based on spino-pelvic alignment. The clinical relevance is that clinicians need to keep in mind when planning treatment that subjects with L5-S1 spondylolisthesis are a heterogeneous group with various adaptations of their posture. In the current controversy on whether high-grade deformities should or should not be reduced, it is suggested that reduction techniques should preferably be used in subjects with evidence of abnormal posture, in order to restore global spino-pelvic balance and improve the biomechanical environment for fusion.

Butterworth R.F.,University of Montreal | Butterworth R.F.,Neuroscience Research Unit
Metabolic Brain Disease | Year: 2013

Acquired hepatolenticular degeneration, also known as "Parkinsonism in cirrhosis" is characterized by extrapyramidal symptoms including hypokinesia, dystonia and rigidity that are rapidly progressive and may be independent of the severity of cognitive dysfunction. Magnetic resonance imaging reveals T1-weighted hyperintense signals in both globus pallidus and substantia nigra. Estimates of the prevalence of Parkinsonism in cirrhosis have been reported as high as 21 %. The cause of Parkinsonism in cirrhosis has been attributed to manganese deposition in basal ganglia structures, leading to the dysfunction of the dopaminergic neurotransmitter system. In particular, there is evidence from both spectroscopic and biochemical investigations for damage to (or dysfunction of) presynaptic dopamine transporters together with a loss of post-synaptic dopamine receptors in basal ganglia of affected patients. Therapeutic options are limited; ammonia-lowering strategies are without substantial benefit, and an effective manganese chelator is not available. In many patients, L-Dopa replacement therapy and the dopamine receptor agonist bromocriptine are beneficial, and liver transplantation is generally effective. However, reports of post-transplant residual extrapyramidal symptoms suggest an element of irreversibility in some cases. © 2012 Springer Science+Business Media New York.

Vidal T.,University of Montreal | Crainic T.G.,University of Quebec at Montreal | Gendreau M.,Ecole Polytechnique de Montreal | Lahrichi N.,Ecole Polytechnique de Montreal | Rei W.,University of Quebec at Montreal
Operations Research | Year: 2012

We propose an algorithmic framework that successfully addresses three vehicle routing problems: the multidepot VRP, the periodic VRP, and the multidepot periodic VRP with capacitated vehicles and constrained route duration. The metaheuristic combines the exploration breadth of population-based evolutionary search, the aggressive-improvement capabilities of neighborhood-based metaheuristics, and advanced population-diversity management schemes. Extensive computational experiments show that the method performs impressively in terms of computational efficiency and solution quality, identifying either the best known solutions, including the optimal ones, or new best solutions for all currently available benchmark instances for the three problem classes. The proposed method also proves extremely competitive for the capacitated VRP. © 2012 INFORMS.

Alberts I.,Cogniva Information Science Research Institute | Forest D.,University of Montreal
Journal of the American Society for Information Science and Technology | Year: 2012

This paper presents a two-phased research project aiming to improve email triage for public administration managers. The first phase developed a typology of email classification patterns through a qualitative study involving 34 participants. Inspired by the fields of pragmatics and speech act theory, this typology comprising four top level categories and 13 subcategories represents the typical email triage behaviors of managers in an organizational context. The second study phase was conducted on a corpus of 1,703 messages using email samples of two managers. Using the k-NN (k-nearest neighbor) algorithm, statistical treatments automatically classified the email according to lexical and nonlexical features representative of managers' triage patterns. The automatic classification of email according to the lexicon of the messages was found to be substantially more efficient when ka=2 and na=2,000. For four categories, the average recall rate was 94.32%, the average precision rate was 94.50%, and the accuracy rate was 94.54%. For 13 categories, the average recall rate was 91.09%, the average precision rate was 84.18%, and the accuracy rate was 88.70%. It appears that a message's nonlexical features are also deeply influenced by email pragmatics. Features related to the recipient and the sender were the most relevant for characterizing email. © 2012 ASIS&T.

Daher F.B.,University of Montreal
Plant signaling & behavior | Year: 2012

An important player in actin remodeling is the actin depolymerizing factor (ADF) which increases actin filament treadmilling rates. Previously, we had prepared fluorescent protein fusions of two Arabidopsis pollen specific ADFs, ADF7 and ADF10. These had enabled us to determine the temporal expression patterns and subcellular localization of these proteins during male gametophyte development. Here we generated stable transformants containing both chimeric genes allowing for simultaneous imaging and direct comparison. One of the striking differences between the two proteins was the localization profile in the growing pollen tube apex. Whereas ADF10 was associated with the filamentous actin array forming the subapical actin fringe, ADF7 was present in the same cytoplasmic region, but in diffuse form. This suggests that ADF7 is involved in the high actin turnover that is likely to occur in the fringe by continuously and efficiently depolymerizing filamentous actin and supplying monomeric actin to the advancing end of the fringe. The possibility to visualize both of these pollen-specific ADFs simultaneously opens avenues for future research into the regulatory function of actin binding proteins in pollen.

In this paper, high quality spectropolarimetric observations of the Wolf-Rayet (WR) star WR1 (HD 4004) obtained with ESPaDOnS at the Canada-France-Hawaii Telescope are presented. All major emission lines present in the spectrum show depolarization in the relative Stokes parameters Q/I and U/I. From the behavior of the amount of line depolarization as a function of line strength, the intrinsic continuum light polarization of WR1 is estimated to be P/I = 0.443% ± 0.028% with an angle of θ = -26.°2. Although such a level of polarization could in principle be caused by a wind flattened by fast rotation, the scenario in which it is a consequence of the presence of corotating interaction regions (CIRs) in the wind is preferred. This is supported by previous photometric and spectroscopic observations showing periodic variations with a period of 16.9 days. This is now the third WR star thought to exhibit CIRs in its wind that is found to have line depolarization. Previous authors have found a strong correlation between line depolarization and the presence of an ejected nebula, which they interpret as a sign that the star has relatively recently reached the WR phase since the nebula are thought to dissipate very fast. In cases where the presence of CIRs in the wind is favored to explain the depolarization across spectral lines, the above-mentioned correlation may indicate that those massive stars have only very recently transited from the previous evolutionary phase to the WR phase. © 2013. The American Astronomical Society. All rights reserved..

Beauchamp G.,University of Montreal
Biology Letters | Year: 2011

How individuals migrate over long distances is an enduring mystery of animal migration. Strong selection pressure for travelling in groups has been suggested in long-distance migrating species. Travelling in groups can reduce the energetic demands of long migration, increase navigational accuracy and favour group foraging at migratory halts. Nevertheless, this hypothesis has received scant attention. I examined evolutionary transitions in migration distance in all North American breeding species of birds. I documented 72 evolutionary shifts inmigrationdistance in thepool of 409 species. In contrasting clades, long-distance migration, as opposed to short-distance migration, was associated with a larger travelling group size. No other transitions occurred alongside in other traits such as group size in the non-breeding season or body mass. The results suggest that larger group sizes have been beneficial in the evolution of long-distance migration in a large clade of birds. © 2011 The Royal Society.

Botev Z.I.,University of Montreal | Kroese D.P.,University of Queensland
Statistics and Computing | Year: 2012

We describe a new Monte Carlo algorithm for the consistent and unbiased estimation of multidimensional integrals and the efficient sampling from multidimensional densities. The algorithm is inspired by the classical splitting method and can be applied to general static simulation models. We provide examples from rare-event probability estimation, counting, and sampling, demonstrating that the proposed method can outperform existing Markov chain sampling methods in terms of convergence speed and accuracy. © 2010 Springer Science+Business Media, LLC.

Winnik F.M.,University of Montreal | Winnik F.M.,Japan International Center for Materials Nanoarchitectonics | Maysinger D.,McGill University
Accounts of Chemical Research | Year: 2013

The dramatic increase in the use of nanoparticles (NP) in industry and research has raised questions about the potential toxicity of such materials. Unfortunately, not enough is known about how the novel, technologically- attractive properties of NPs correlate with the interactions that may take place at the nano/bio interface. The academic, industrial, and regulatory communities are actively seeking answers to the growing concerns on the impact of nanotechnology on humans. In this Account we adopt quantum dots (QDs) as an illustrative example of the difficulties associated with the development of a rational science-based approach to nanotoxicology.The optical properties of QDs are far superior to those of organic dyes in terms of emission and absorption bandwidths, quantum yield, and resistance to photobleaching. Moreover, QDs may be decorated with targeting moieties or drugs and, therefore, are candidates for site-specific medical imaging and for drug delivery, for example in cancer treatment. Earlier this year researchers demonstrated that QD-based imaging using monkeys caused no adverse effects although QDs accumulated in lymph nodes, bone marrow, liver, and spleen for up to 3 months after injection. Such persistence of QDs in live animals does, however, raise concerns about the safety of using QDs both in the laboratory and in the clinic.Researchers anticipate that QDs will be increasingly used not only in clinical applications but also in various manufactured products. For example, QD-solar cells have emerged as viable contenders to complement or replace dye-sensitized solar cells; CdTe/CdS thin film cells have already captured approximately 10 percent of the global market, and in addition, QDs can serve as components of sensors and as emitting materials in LEDs. Given the clear indications that QDs will inevitably become components of a wide range of manufactured and consumer products, researchers and policy makers need to understand the possible health risks associated with exposure to QDs.In this Account, we initially review the known mechanisms by which QDs can damage cells, including oxidative stress elicited by reactive oxygen species (ROS). We discuss lesser-known impairments induced in cells by nanomolar to picomolar concentrations of QDs, which imply that cadmium-containing QDs can exert genotoxic, epigenetic, and metalloestrogenic effects. These observations strongly suggest that minute concentrations of QDs could be sufficient to cause long lasting, even transgenerational, effects. We also consider various modes by which humans could be exposed to QDs in their work or through the environment. Although considerable advances have been made in enhancing the stability and overall quality of QDs, over time they can partially degrade in the environment or in biological systems, and eventually cause small, but cumulative undesirable effects.A combination of toxicological, genetic, epigenetic and imaging approaches is required to create comprehensive guidelines for evaluating the nanotoxicity of nanomaterials, including QDs. Prior to biological investigations with these materials, an indispensible step must be the full characterization of NPs by complementary techniques. Specifically, the concentration, size, charge, and ligand stability of NPs in biological media must be known if we are to understand fully how the properties of nanoparticles and of their biological environment contribute to cytotoxicity. © 2012 American Chemical Society.

Lamothe V.,University of Montreal
Journal of Physics A: Mathematical and Theoretical | Year: 2012

A group analysis of a system describing an ideal plastic flow is made in order to obtain analytical solutions. The complete Lie algebra of point symmetries of this system are given. Two of the infinitesimal generators that span the Lie algebra are original to this paper. A classification into conjugacy classes of all one- and two-dimensional subalgebras is performed. Invariant and partially invariant solutions corresponding to certain conjugacy classes are obtained using the symmetry reduction method. Solutions of algebraic, trigonometric, inverse trigonometric and elliptic type are provided as illustrations and other solutions expressed in terms of one or two arbitrary functions have also been found. For some of these solutions, a physical interpretation allows one to determine the shape of feasible extrusion dies corresponding to these solutions. The corresponding tools could be used to curve rods or slabs, or to shape a ring in an ideal plastic material by an extrusion process. © 2012 IOP Publishing Ltd.

Robert M.-C.,Notre Dame Hospital | Pomerleau V.,University of Montreal | Harissi-Dagher M.,Notre Dame Hospital
British Journal of Ophthalmology | Year: 2013

Background/aims To compare the complications leading to best-corrected visual acuity (BCVA) loss in patients with Boston keratoprosthesis type 1 (KPro) and glaucoma drainage device (GDD) and those with KPro alone. Methods Retrospective case series of all patients who underwent KPro surgery at the Centre Hospitalier de l'Université de Montréal between 2008 and 2011. Preoperative diagnoses, BCVA and complications were tabulated and analysed. Results KPro surgery was performed in 96 eyes: 18 eyes (19%) had KPro and GDD while 78 eyes (81%) had KPro only. Median BCVA at postoperative 6 months was 20/150 in both groups. Seven eyes (39%) with KPro and GDD experienced vision loss due to complications such as glaucoma progression (three eyes, 22%), tube occlusion (four eyes, 22%) and choroidal haemorrhage (three eyes, 17%). Vitreous incarceration was the most common cause of tube occlusion. Vitreoretinal, glaucoma and infectious complications caused BCVA loss in 16 eyes (21%) with KPro alone ( p=0.13). Conclusions Glaucoma progression is a major cause of visual decline post-KPro. However, GDD implantation should only be performed in carefully selected patients. Because of a high risk of vitreous incarceration within the tube, a complete pars plana vitrectomy should be performed prior to GDD implantation.

Lamothe V.,University of Montreal
Journal of Mathematical Physics | Year: 2012

In this paper, we study a finite-dimensional Lie point symmetry group of a system describing an ideal plastic plane flow in two dimensions in order to find analytical solutions. The infinitesimal generators that span this Lie algebra are given. We completely classify the subalgebras of codimension up to two into conjugacy classes under the action of the symmetry group. Based on invariant forms, we use Ansätze to compute symmetry reductions in such a way that the obtained solutions simultaneously cover many invariant and partially invariant solutions. We calculate solutions of algebraic, trigonometric, inverse trigonometric and elliptic type. Some solutions depending on one or two arbitrary functions of one variable have also been found. In some cases, the shape of a potentially feasible extrusion die corresponding to the solution is deduced. These tools could be used to thin, curve, undulate or shape a ring in an ideal plastic material. © 2012 American Institute of Physics.

Rodrigue N.,University of Ottawa | Philippe H.,University of Montreal
Trends in Genetics | Year: 2010

The physical sciences have long recognized the distinction between formal descriptions of observations versus explanations for observations, with the canonical example embodied in the axiom statistical mechanics explains thermodynamics. Descriptive models are often said to be phenomenologically motivated whereas explanatory models are said to be mechanistically motivated. In molecular evolutionary modeling the two approaches can typically be classified as dealing with either the inference of phylogenies - the phenomenological approach, lacking particular interest in evolutionary mechanisms per se, or focused on explaining the evolutionary process itself - the mechanistic approach. Here we emphasize that both phenomenological and mechanistic approaches are inherently present in any model. Focusing on the field of codon substitution modeling we point out that this area, traditionally viewed as being mechanistically motivated, has itself been imbued with phenomenological underpinnings. Using practical examples we stress that clarifying phenomenological and mechanistic motivations can help guide model developments, and suggest future work directions. © 2010 Elsevier Ltd.

The quantification of neuropeptides may play a significant role in future drug development targeting central nervous system functions. Adequate method precision and accuracy is essential, and sample stability is an important factor. This study compares three sample preparation protocols and assesses the stability of targeted neuropeptides under standard laboratory conditions. The results show that the concentrations of substance P, dynorphin A, and calcitonin gene-related peptide (CGRP) change significantly in time when spinal cord tissues are homogenized in phosphate-buffered saline (PBS) buffer or PBS buffer containing a mammalian protease inhibitor cocktail but is stabilized when tissues are homogenized in a 0.25% trifluoroacetic acid solution. © 2010.

Chene A.-N.,National Research Council Canada | St-Louis N.,University of Montreal
Astrophysical Journal | Year: 2010

We present the results of an intensive photometric and spectroscopic monitoring campaign of the WN4 Wolf-Rayet (WR) star WR 1 = HD 4004. Our broadband V photometry covering a timespan of 91 days shows variability with a period of P = 16.9+0.6 -0.3 days. The same period is also found in our spectral data. The light curve is non-sinusoidal with hints of a gradual change in its shape as a function of time. The photometric variations nevertheless remain coherent over several cycles and we estimate that the coherence timescale of the light curve is of the order of 60 days. The spectroscopy shows large-scale line-profile variability which can be interpreted as excess emission peaks moving from one side of the profile to the other on a timescale of several days. Although we cannot unequivocally exclude the unlikely possibility that WR 1 is a binary, we propose that the nature of the variability we have found strongly suggests that it is due to the presence in the wind of the WR star of large-scale structures, most likely corotating interaction regions (CIRs), which are predicted to arise in inherently unstable radiatively driven winds when they are perturbed at their base. We also suggest that variability observed in WR6, WR 134, and WR 137 is of the same nature. Finally, assuming that the period of CIRs is related to the rotational period, we estimate the rotation rate of the four stars for which sufficient monitoring has been carried out, i.e., v rot = 6.5, 40, 70, and 275 km s -1 for WR 1, WR6, WR 134, and WR 137, respectively. © 2010. The American Astronomical Society. All rights reserved.

Bengio Y.,University of Montreal
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

Learning algorithms related to artificial neural networks and in particular for Deep Learning may seem to involve many bells and whistles, called hyper-parameters. This chapter is meant as a practical guide with recommendations for some of the most commonly used hyperparameters, in particular in the context of learning algorithms based on back-propagated gradient and gradient-based optimization. It also discusses how to deal with the fact that more interesting results can be obtained when allowing one to adjust many hyper-parameters. Overall, it describes elements of the practice used to successfully and efficiently train and debug large-scale and often deep multi-layer neural networks. It closes with open questions about the training difficulties observed with deeper architectures. © Springer-Verlag Berlin Heidelberg 2012.

There is no research on the timing, sequencing and number of changes in family environment and their influences on sexual and reproductive health outcomes in Africa. Using a population-based survey with data on family structure at three points in the life course, this paper examines the influences of these family structure dynamics on the timing of first sex among unmarried males and females aged 12-24 years in Cameroon. The number and timing of family transitions significantly impacted the timing of sexual debut for both males and females. The median age at first sex (18.7 years) is higher among young people without family transition than among those with one transition (18.2 years) or two transitions (17.7 years). Family transitions occurring during childhood were significantly associated with premature sexual initiation for females but not for males. Reproductive health and social development interventions for young people in Africa should integrate the changing contexts and transitions in family structure.

Butterworth R.F.,University of Montreal
Molecular Genetics and Metabolism | Year: 2014

Ineffective hepatic clearance of excess ammonia in the form of urea, as occurs in urea cycle enzymopathies (UCDs) and in liver failure, leads to increases in circulating and tissue concentrations of glutamine and a positive correlation between brain glutamine and the severity of neurological symptoms. Studies using 1H/13C Nuclear Magnetic Resonance (NMR) spectroscopy reveal increased de novo synthesis of glutamine in the brain in acute liver failure (ALF) but increases of synthesis rates per se do not correlate with either the severity of encephalopathy or brain edema. Skeletal muscle becomes primarily responsible for removal of excess ammonia in liver failure and in UCDs, an adaptation that results from a post-translational induction of the glutamine synthetase (GS) gene. The importance of muscle in ammonia removal in hyperammonemia accounts for the resurgence of interest in maintaining adequate dietary protein and the use of agents aimed at the stimulation of muscle GS. Alternative or additional metabolic and regulatory pathways that impact on brain glutamine homeostasis in hyperammonemia include (i) glutamine deamination by the two isoforms of glutaminase, (ii) glutamine transamination leading to the production of the putative neurotoxin alpha-ketoglutaramate and (iii) alterations of high affinity astrocytic glutamine transporters (SNATs). Findings of reduced expression of the glutamine transporter SNAT-5 (responsible for glutamine clearance from the astrocyte) in ALF raise the possibility of "glutamine trapping" within these cells. Such a trapping mechanism could contribute to cytotoxic brain edema and to the imbalance between excitatory and inhibitory neurotransmission in this disorder. © 2014.

There is evidence that some atypical antipsychotics, including olanzapine, can produce unwanted metabolic side effects, weight gain and diabetes. However, neuronal correlates of change related to food information processing have not been investigated with these medications. We studied the effect of a pharmacological manipulation with an antipsychotic known to cause weight gain on metabolites, cognitive tasks and neural correlates related to food regulation. We used functional magnetic resonance imaging in conjunction with a task requiring visual processing of appetitive stimuli in schizophrenic patients and healthy controls before and after 16 weeks of antipsychotic medication with olanzapine. In patients, the psychological and neuronal changes associated following the treatment correlated with appetite control measures and metabolite levels in fasting blood samples. After 16 weeks of olanzapine treatment, the patients gained weight, increased their waist circumference, had fewer positive schizophrenia symptoms, a reduced ghrelin plasma concentration and an increased concentration of triglycerides, insulin and leptin. In premotor area, somatosensory cortices as well as bilaterally in the fusiform gyri, the olanzapine treatment increased the neural activity related to appetitive information in schizophrenic patients to similar levels relative to healthy individuals. However, a higher increase in sensitivity to appetitive stimuli after the treatment was observed in insular cortices, amygdala and cerebellum in schizophrenic patients as compared with healthy controls. Furthermore, these changes in neuronal activity correlated with changes in some metabolites and cognitive measurements related to appetite regulation.

Schiettekatte F.,University of Montreal
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2014

Monte Carlo simulation software applied to ion beam analysis use the main scattering event (MSE) approximation. This approximation consist in generating ion trajectories in different directions, making the detection rate independent of the cross-section dependence on the scattering angle, therefore speeding up calculations by a factor 104-106. The event generated bear a probability weight proportional to the cross-section, so in the case of Rutherford backscattering spectrometry (RBS), events generated with a small scattering angle bear a very large weight, sometimes producing few events with a very large amplitude in the spectrum. They are avoided by setting a cut-off angle, but the signal they represent is in fact an actual contribution to the background signal. Here, it is shown that experimental spectra that include a significant contribution from several wide-angle scattering, such as tails or background signal in heavy ion RBS can be reproduced by a combination of two simulations: one featuring at least one wide-angle scattering, simulated accurately within the MSE approximation, and a background signal part, corresponding to trajectories featuring a series of small-angle scattering, simulated without the MSE approximation; this second simulation is achieved in a few minutes by increasing the detector size and mean free path by large factors, typically 100 each. The events included from the two parts of the simulation are discriminated by the minimum angle of the MSE. © 2014 Elsevier B.V. All rights reserved.

Dang M.T.,French National Center for Scientific Research | Hirsch L.,French National Center for Scientific Research | Wantz G.,French National Center for Scientific Research | Wantz G.,University of Montreal
Advanced Materials | Year: 2011

In the field of polymer-based photovoltaic cells, poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]C 61 (PCBM) are, to date, the most-studied active materials around the world for the bulk-heterojunction structure. Various power-conversion efficiencies are reported up to approximately 5%. This Research News article is focused on a survey of the tremendous literature published between 2002 and 2010 that exhibits solar cells based on blends of P3HT and PCBM. This Research News article is a survey of the tremendous amount of literature published from 2002 to 2010 that exhibits polymeric solar cells based on the well-known bulk heterojunction based on P3HT and PCBM. The power-conversion-efficiency discrepancy is correlated with the solar-cell-fabrication parameters. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bhattacharya B.,University of Montreal | Gronau M.,Technion - Israel Institute of Technology | Rosner J.L.,University of Chicago
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

The LHCb Collaboration has recently reported evidence for a CP asymmetry approaching the percent level in the difference between D0→π +π - and D0→K +K -. We analyze this effect as if it is due to a penguin amplitude with the weak phase of the standard model c→b→u loop diagram, but with a CP-conserving enhancement as if due to the strong interactions. In such a case the magnitude and strong phase of this amplitude P b are correlated in order to fit the observed CP asymmetry, and one may predict CP asymmetries for a number of other singly-Cabibbo-suppressed decays of charmed mesons to a pair of pseudoscalar mesons. Nonzero CP asymmetries are expected for D +→K +K ̄0 (the most promising channel for which a nonzero CP asymmetry has not yet been reported), as well as D0→π0π0, Ds+→π +K0, and D s→π 0K +. No CP asymmetry is predicted for D +→π +π0 or D0→K0K ̄0 in this framework. © 2012 American Physical Society.

Segura M.,University of Montreal
Expert Review of Vaccines | Year: 2015

Streptococcus suis is a major swine pathogen and an emerging zoonotic agent of human meningitis and streptococcal toxic shock-like syndrome. S. suis is a well-encapsulated pathogen and multiple serotypes have been described based on the capsular polysaccharide antigenic diversity. In addition, high genotypic, phenotypic and geographic variability exits among strains within the same serotype. Besides, S. suis uses an arsenal of virulence factors to evade the host immune system. Together, these characteristics have challenged the development of efficacious vaccines to fight this important pathogen. In this careful and comprehensive review, clinical field information and experimental data have been compiled and compared for the first time to give a precise overview of the current status of vaccine development against S. suis. The candidate antigens and vaccine formulations under research are examined and the feasibility of reaching the goal of a "universal" cross-protective S. suis vaccine discussed. © 2015 Taylor & Francis.

Momparler R.L.,University of Montreal
Frontiers in Oncology | Year: 2013

Epigenetic analysis shows that many genes that suppress malignancy are silenced by aberrant DNA methylation in lung cancer. Many of these genes are interesting targets for reactivation by the inhibitor of DNA methylation, decitabine (5-aza-2'-deoxycytidine, DAC). A pilot study on intense dose DAC showed promising results in patients with metastatic non-small cell lung cancer (NSCLC). However, subsequent clinical studies using low dose DAC were not very effective against NSCLC and interest in this therapy diminished. Recently, interesting responses were observed in a patient with NSCLC following treatment with a combination of the related inhibitor of DNA methylation, 5-azacytidine, and an inhibitor of histone deacetylation. This finding has generated a renewed interest in the epigenetic therapy of lung cancer. Preclinical studies indicate that DAC has remarkable chemotherapeutic potential for tumor therapy. This epigenetic agent has a delayed and prolonged epigenetic action on tumor cells. This delayed action should be taken into consideration in the design and evaluation of clinical studies on DAC. Future research should be directed at finding the optimal dose-schedule of de DAC for the treatment of NSCLC. © 2013 Momparler.

Angiogenesis is a necessary process for tumor progression and is driven through molecular interactions between cancer cells and neighboring vascular endothelial cells. The primary mediators of angiogenesis are the vascular endothelial growth factors and their respective receptors on endothelial cells. There are several U.S. Food and Drug Administration-approved anti-angiogenic agents in clinical use. In head and neck cancer there are clinical trials assessing the efficacy of anti-angiogenic agents in combination with chemoradiation therapy. Although the aforementioned growth factors and receptors have been traditionally viewed as anti-angiogenic targets, there are concomitant efforts to understand the role these molecules play within the tumor cells. In this review, we first discuss the biology of angiogenic proteins and the targeting of angiogenic molecules for cancer treatment. We summarize the current clinical trials of anti-angiogenic therapies in head and neck squamous cell carcinoma. Finally, the additional role these molecules play in tumor progression independent of angiogenesis is discussed. Copyright © 2010 Wiley Periodicals, Inc.

Saad F.,University of Montreal | Miller K.,Charite - Medical University of Berlin
Urologic Oncology: Seminars and Original Investigations | Year: 2014

Background: Docetaxel-based chemotherapy remains the standard of care for metastatic castration-resistant prostate cancer (mCRPC) and it is the only globally approved first-line therapy. Although docetaxel offers improved survival for this patient population, it is also associated with toxicity and resistance in many patients, representing a need for more efficacious therapies. Preclinical advances have led to improved understanding of the molecular biology of prostate cancer, and targeted therapies that exploit the signaling pathways and molecular targets that underscore the disease are being clinically investigated in combination with docetaxel. Design: This article briefly highlights recent data from phase III trials in mCRPC that have led to agent approval. This article also reviews phase II and III trials in which docetaxel-based regimens have been investigated in mCRPC. Results: Recently approved agents, including sipuleucel-T, cabazitaxel, abiraterone acetate, and enzalutamide, have diversified the mCRPC treatment landscape. Phase III trials evaluating docetaxel in combination with targeted therapies, including potent oral tyrosine kinase inhibitor, dasatinib, in the READY trial and clusterin inhibitor, custirsen, in the SYNERGY trial, are currently ongoing. Conclusions: In combination with docetaxel, targeted agents dasatinib and custirsen will likely expand the existing treatment paradigm for mCRPC if results from phase III trials are positive. © 2014 Elsevier Inc.

Jenson J.,University of Montreal
Global Social Policy | Year: 2010

By the mid-1990s neo-liberalism had begun to reach its economic, social and political limits. International as well national and even sub-national social policymakers in and concerned with Latin America and Europe began to converge around new ideas about doing social policy, characterized here as the social investment perspective. The first section of the article documents this convergence across two regions. The second section then identifies three social mechanisms that supported this convergence. The first began in the heyday of neo-liberalism, and involved opening space for legitimate alternatives. A second was the polysemic character of social investment as a quasi-concept that could penetrate and link numerous policy communities. The third was boundary-crossing, as distinctions that had separated analysis and action in the two regions fell away. © The Author(s), 2010.

In societies with a high level of population aging, the ability to live autonomously is a major goal of public health. The present article examines recent population-based studies analyzing a possible reduction in the prevalence of disability and provides evidence on the unmet needs of dependent individuals.In the last few decades, disability and reduced mobility have decreased in elderly persons living in high-income countries, including Spain. This decrease is clear in persons aged less than 85 years old but the trends in persons older than 85 years are difficult to study due to the lack of information. These trends depend on greater education among the population, a reduction in social and gender inequalities and the adoption of healthy lifestyle habits. A reduction in dependency also depends on changes in the physical and social environment to encourage active aging. The health gains in the generation aged between 40 and 65 years do not seem high. The reductions in disability in the next 25 years will not be as great as those observed between 1990 and the present time, except for a possible reduction in disability in women due to a decrease in gender roles. Dependence on help from third persons will tend to decrease, except in dementia. Use of technical aids is increasing and will continue to do so. © 2011 SESPAS.

Infections with encapsulated bacteria cause serious clinical problems. Besides being poorly immunogenic, the bacterial capsu