IBMC Institute for Molecular and Cell Biology

Vila Franca do Campo, Portugal

IBMC Institute for Molecular and Cell Biology

Vila Franca do Campo, Portugal
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Sousa J.L.R.,IBMC Institute for Molecular and Cell Biology | Mendes J.F.F.,University of Aveiro | Machado R.J.,University of Minho
Information Systems Development: Transforming Organisations and Society Through Information Systems - Proceedings of the 23rd International Conference on Information Systems Development, ISD 2014 | Year: 2014

Business/IT Alignment is an information systems research field with a long existence and a high number of researchers and represents a central thinking direction over the entanglement between business and information systems. It aims to achieve a paradigm, on which there is a high degree of visibility and availability of information about the information systems sociomateriality. Complex-networks constitute an approach to the study of the emergent properties of complex-systems that strongly focuses and relies on models and measures, through which the system interdependence is built. Several characteristics of complexnetworks are: structural or functional topology; domain independent; quantification of elements' relationships; visibility and capture of emergent properties. We introduce a set of models and measures through the dimensions of a profiling framework illustrated with an exploratory case. The introduced models and measures intend to derive information systems effects in Business/IT Alignment.

Afonso R.,University of Porto | Afonso R.,IBMC Institute for Molecular and Cell Biology | Gales L.,IBMC Institute for Molecular and Cell Biology | Gales L.,Abel Salazar Biomedical Sciences Institute | Mendes A.,University of Porto
Microporous and Mesoporous Materials | Year: 2016

A new thermodynamic approach is proposed to interpret adsorption equilibrium in ultramicropores with single-file adsorption. By considering the adsorbed phase as a one-dimensional fluid, phase equilibria thermodynamics can be used to derive a one-dimensional analogue of the monocomponent Gibbs adsorption isotherm. Equations such as Langmuir, Volmer, Fowler-Guggenheim or Hill-de Boer can thus be used as representations of phenomenological models of the one-dimensional adsorption system, rather than just as mathematical correlations. The bidirectional relation between the equations of state characterising the adsorbed phase and the adsorption isotherm equations allow great insight to be had simply by adsorption isotherm determination. In order to show the potential and limitations of this approach, the adsorption isotherms of Xe and CO2 in four crystalline hydrophobic dipeptides of the VA-class are analysed with this approach. It was possible to assess that adsorbate-adsorbate interactions are relevant for adsorption of both species, being attractive for Xe and repulsive for CO2; Xe adsorption is mainly distributed while CO2 adsorption is mainly localised. © 2016 Elsevier Inc.

Cavaleiro F.I.,University of Porto | Pina S.,University of Porto | Russell-Pinto F.,University of Porto | Rodrigues P.,IBMC Institute for Molecular and Cell Biology | And 3 more authors.
Parasitology Research | Year: 2012

The morphology, ultrastructure, genetics, and morphometrics of a species of Diplostomum von Nordmann 1832 (Digenea: Diplostomidae), isolated from the European flounder (Platichthys flesus (L.)) caught off the northwest coast of Portugal, are characterized. The metacercarial stage was found unencysted in the lens capsule of the eye. Light microscopical observations revealed the existence of some variability in specimen shape and size, with two morphotypes, referred to as "round" and "long", being apparent. Scanning electron microscopy revealed a smooth, unarmed tegument, with the lappet region being the most irregular and porose. Both the oral and ventral suckers were provided with a series of papillae, which presented very distinctive ultrastructural features and were particularly conspicuous in the case of the ventral sucker. The two morphotypes detected were found to have 100% genetic correspondence in the 18S+ITS1+5.8S region of the rDNA. Since the genetic data for this metacercaria differed from those of the species of Diplostomum available in GenBank, a description of a new genotype (accession number GQ370809) is provided. The molecular phylogenetic analyses, in conjunction with principal components and cluster analyses based on morphometric data, revealed the existence of consistent differences between the Diplostomum sp. metacercariae from flounder compared with Diplostomum spathaceum, Diplostomum mergi, Diplostomum pseudospathaceum, and Diplostomum paracaudum. The latter of these species was found to be the most similar to the present material. Our results do not support an evolutionary separation of the European and North American species of Diplostomum. © Springer-Verlag 2011.

Afonso R.,IBMC Institute for Molecular and Cell Biology | Afonso R.,University of Porto | Mendes A.,University of Porto | Gales L.,IBMC Institute for Molecular and Cell Biology | Gales L.,Abel Salazar Biomedical Sciences Institute
Physical Chemistry Chemical Physics | Year: 2014

The adsorption isotherms of nitrogen, oxygen and argon in four VA-class hydrophobic dipeptides are presented. Isotherms were determined at 5, 20 and 35°C, for a pressure range of 0-6 bar. Under these conditions, adsorption is still in the Henry region. For all materials and temperatures, the sequence of preferential adsorption is Ar > O2 > N2, a highly abnormal result. At 5 °C, the dipeptide with the smallest pores, VI, has Ar/O2 adsorption equilibrium selectivities up to 1.30, the highest ever measured in Ag-free adsorbents. Gas uptakes, at 1 bar and 20 °C, are ∼0.05 mol kg-1, very low relative values that are partially explained by the low porosity of the solids (<10%). The significance of these results for the development of new materials for the process of O2 generation by pressure swing adsorption (PSA) is discussed. The results indicate some of the structural and chemical properties that prospective Ag-free adsorbents should have in order to have Ar/O2 selectivity, hydrophobic pores, less than 0.5 nm-wide, and porosity of, at least, 20%. © 2014 The Owner Societies.

Afonso R.,University of Porto | Afonso R.,IBMC Institute for Molecular and Cell Biology | Gales L.,IBMC Institute for Molecular and Cell Biology | Gales L.,Abel Salazar Biomedical Sciences Institute | Mendes A.,University of Porto
Adsorption | Year: 2016

The Langmuir equation is one of the most successful adsorption isotherm equations, being widely used to fit Type I adsorption isotherms. In this article we show that the kinetic approach originally used by Langmuir for 2D monolayer surface adsorption can also be used to derive a 1D analogue of the equation, applicable in ultramicropores with single-file diffusion. It is hoped that such a demonstration helps dispel the idea that the Langmuir isotherm equation cannot apply to some micropores as more than a mathematical correlation. We furthermore seek to extend the insight provided by the simple kinetic derivation of the Langmuir equation to other isotherm equations capable of modelling Type I isotherms. The same kinetic approach is thus also used to derive the Volmer, Fowler–Guggenheim and Hill–de Boer equations, both for surface (2D adsorbed phase) and micropore adsorption (1D and 3D adsorbed phases). It is hoped that this will help make more intuitively clear that these equations can be used as phenomenological models in some instances of adsorption in micropores. © 2016 Springer Science+Business Media New York

Pires R.H.,Semmelweis University | Saraiva M.J.,IBMC Institute for Molecular and Cell Biology | Saraiva M.J.,Abel Salazar Biomedical Sciences Institute | Damas A.M.,IBMC Institute for Molecular and Cell Biology | And 2 more authors.
Journal of Molecular Recognition | Year: 2011

Transthyretin (TTR) is an important human transport protein present in the serum and the cerebrospinal fluid. Aggregation of TTR in the form of amyloid fibrils is associated with neurodegeneration, but the mechanisms of cytotoxicity are likely to stem from the presence of intermediate assembly states. Characterization of these intermediate species is therefore essential to understand the etiology and pathogenesis of TTR-related amyloidoses. In the present work we used atomic force microscopy to investigate the morphological features of wild-type (WT) TTR amyloid protofibrils that appear in the early stages of aggregation. TTR protofibrils obtained by mild acidification appeared as flexible filaments with variable length and were able to bind amyloid markers (thioflavin T and Congo red). Surface topology and contour-length distribution displayed a periodic pattern of â15ânm, suggesting that the protofibrils assemble via an end-binding oligomer fusion mechanism. The average height and periodic substructure found in protofibrils is compatible with the double-helical model of the TTR amyloid protofilament. Over time protofibrils aggregated into bundles and did not form mature amyloid-like fibrils. Unlike amyloid fibrils that are typically stable under physiological conditions, the bundles dissociated into component protofibrils with axially compacted and radially dilated structure when exposed to phosphate-buffered saline solution. Thus, WT TTR can form metastable filamentous aggregates that may represent an important transient state along the pathway towards the formation of cytotoxic TTR species. Copyright © 2011 John Wiley & Sons, Ltd.

Abreu C.,Hospital S Joao | Abreu C.,University of Porto | Magro F.,Hospital S Joao | Magro F.,University of Porto | And 9 more authors.
Journal of Crohn's and Colitis | Year: 2013

Listeria monocytogenes is an aerobic gram positive intracellular bacillus, predominantly affecting pregnant women, immunocompromised patients and old individuals. Invasive listeriosis, meningitis and meningoencephalitis, bacteraemia with or without joint, eye or heart focalization are clinical manifestations of the disease. Anti-TNF-α drugs blocking the host's response against various microorganisms, particularly intracellular agents like Listeria monocytogenes, increase the risk of disease. We report two cases of L. monocytogenes meningitis in ulcerative colitis patients under infliximab plus steroids. One patient is HIV-1 infected. A review of reported invasive listeriosis cases under anti-TNF drugs is also showed. © 2012 European Crohn's and Colitis Organisation.

Santinha D.R.,University of Coimbra | Marques D.R.,University of Aveiro | Maciel E.A.,University of Aveiro | Simoes C.S.O.,University of Aveiro | And 6 more authors.
Analytical and Bioanalytical Chemistry | Year: 2012

Lipids are important in several biological processes because they act as signalling and regulating molecules, or, locally, as membrane components that modulate protein function. This paper reports the pattern of lipid composition of dendritic cells (DCs), a cell type of critical importance in inflammatory and immune responses. After activation by antigens, DCs undergo drastic phenotypical and functional transformations, in a process known as maturation. To better characterize this process, changes of lipid profile were evaluated by use of a lipidomic approach. As an experimental model of DCs, we used a foetal skin-derived dendritic cell line (FSDC) induced to mature by treatment with lipopolysaccharide (LPS). The results showed that LPS treatment increased ceramide (Cer) and phosphatidylcholine (PC) levels and reduced sphingomyelin (SM) and phosphatidylinositol (PI) content. Mass spectrometric analysis of a total lipid extract and of each class of lipids revealed that maturation promoted clear changes in ceramide profile. Quantitative analysis enabled identification of an increase in the total ceramide content and enhanced Cer at m/z 646.6, identified as Cer(d18:1/24:1), and at m/z 648.6, identified as Cer(d18:1/24:0). The pattern of change of these lipids give an extremely rich source of data for evaluating modulation of specific lipid species triggered during DC maturation. © Springer-Verlag 2012.

PubMed | Applied Photophysics Ltd., University of Coimbra, IBMC Institute for Molecular and Cell Biology, Biocant Biotechnology Innovation Center and 2 more.
Type: Journal Article | Journal: The Biochemical journal | Year: 2016

Laforin is a human dual-specificity phosphatase (DSP) involved in glycogen metabolism regulation containing a carbohydrate-binding module (CBM). Mutations in the gene coding for laforin are responsible for the development of Lafora disease, a progressive fatal myoclonus epilepsy with early onset, characterized by the intracellular deposition of abnormally branched, hyperphosphorylated insoluble glycogen-like polymers, called Lafora bodies. Despite the known importance of the CBM domain of laforin in the regulation of glycogen metabolism, the molecular mechanism of laforin-glycogen interaction is still poorly understood. Recently, the structure of laforin with bound maltohexaose was determined and despite the importance of such breakthrough, some molecular interaction details remained missing. We herein report a thorough biophysical characterization of laforin-carbohydrate interaction using soluble glycans. We demonstrated an increased preference of laforin for the interaction with glycans with higher order of polymerization and confirmed the importance of tryptophan residues for glycan interaction. Moreover, and in line with what has been described for other CBMs and lectins, our results confirmed that laforin-glycan interactions occur with a favourable enthalpic contribution counter-balanced by an unfavourable entropic contribution. The analysis of laforin-glycan interaction through the glycan side by saturation transfer difference (STD)-NMR has shown that the CBM-binding site can accommodate between 5 and 6 sugar units, which is in line with the recently obtained crystal structure of laforin. Overall, the work in the present study complements the structural characterization of laforin and sheds light on the molecular mechanism of laforin-glycan interaction, which is a pivotal requisite to understand the physiological and pathological roles of laforin.

PubMed | IBMC Institute for Molecular and Cell Biology, Institute Parasitologia y Biomedicina Lopez Neyra and University of Granada
Type: Journal Article | Journal: International journal for parasitology. Drugs and drug resistance | Year: 2016

Visceral leishmaniasis (VL) caused by the protozoan parasite Leishmania infantum, is one of the most important zoonotic diseases affecting dogs and humans in the Mediterranean area. The presence of infected dogs as the main reservoir host of L. infantum is regarded as the most significant risk for potential human infection. We have studied the susceptibility profile to antimony and other anti-leishmania drugs (amphotericin B, miltefosine, paromomycin) in Leishmania infantum isolates extracted from a dog before and after two therapeutic interventions with meglumine antimoniate (subcutaneous Glucantime(), 100mg/kg/day for 28 days). After the therapeutic intervention, these parasites were significantly less susceptible to antimony than pretreatment isolate, presenting a resistance index of 6-fold to Sb(III) for promastigotes and >3-fold to Sb(III) and 3-fold to Sb(V) for intracellular amastigotes. The susceptibility profile of this resistant L. infantum line is related to a decreased antimony uptake due to lower aquaglyceroporin-1 expression levels. Additionally, other mechanisms including an increase in thiols and overexpression of enzymes involved in thiol metabolism, such as ornithine decarboxylase, trypanothione reductase, mitochondrial tryparedoxin and mitochondrial tryparedoxin peroxidase, could contribute to the resistance as antimony detoxification mechanisms. A major contribution of this study in a canine L. infantum isolate is to find an antimony-resistant mechanism similar to that previously described in other human clinical isolates.

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