Ontario Veterinary College
Ontario Veterinary College
News Article | July 7, 2017
Frogs legs have sprung a big surprise – contrary to textbook biology, they have primitive kneecaps. The kneecaps are made of dense, fibrous cartilage rather than bone, and appear to be much better suited to soaking up the strains of leaping and jumping than the bony human patella. They may have been missed until now because they are not clearly visible on frog leg bones, even with a microscope, says Virginia Abdala of Argentina’s Institute of Neotropical Biodiversity, who led the investigation. The researchers analysed full skeletons of 20 species, but they were only able to see kneecaps in the eight specimens from which they took tissue slices for analysis. One implication of the discovery is that kneecaps like this began to evolve in the Devonian period 400 million years ago, when the first four-legged animals reached land, the researchers say. “Until now it was thought that the evolution of kneecaps coincided with the arrival of tetrapods that lay eggs on land or retain fertilised eggs in the body,” says Abdala. This investigation shows that the process really started with fibrocartilage in frogs, she says. “It could be related to locomotion on land, which may have required reinforcement of precise limb points,” she says. The frogs’ fibrous kneecaps have a lot of elasticity, and so are suited to soaking up the large forces exerted during the act of jumping or leaping once tetrapods reached land. Animals later evolved to walk rather than relying so heavily on jumping, and so developed bony kneecaps better suited to this. “The resting position in frogs is analogous to the jumping position in humans, so the knees of frogs are under constant stress, and the fibrocartilaginous kneecap might alleviate this,” says Abdala. “It does matter what kneecaps are made out of,” says John Hutchinson, also at the Royal Veterinary College. “Bone is a good lever, better at resisting compression than fibrocartilage, so animals using their kneecaps as levers rather than cushions would benefit from bony kneecaps.” “Fibrocartilage is a good cushion, and might be the original state of kneecaps, possibly inherited by all legged land vertebrates.” Abdala agrees: “The structures are probably protecting the knee from the huge mechanical effort necessary for the jumping of frogs”. In contrast, when humans jump, there’s not enough elasticity in the bony patella to soak up these forces, leading to injury and inflammation of the underlying tendons, as in “jumper’s knee”. “I think it’s very exciting to have potentially discovered a patella in frogs,” says Sophie Regnault of the Royal Veterinary College in London. There are hints of non-bony kneecaps in frogs, crocodiles and turtles, and a non-bony kneecap or similar structure is well-documented in marsupials, she adds. Not everyone believes the structures qualify as kneecaps, however. “The authors convincingly demonstrate that some frog species have one, sometimes two, fibrocartilagenous elements adjacent to the knee joint, but it’s premature to identify them as patellae,” says Matthew Vickaryous of Ontario Veterinary College in Canada. He says that similar features – called patelloids – have been found in some mammals, in some cases alongside clearly genuine kneecaps, as in rabbits. Vickaryous also points out that there are around 7000 species of frogs and toads worldwide, so it may not be justified to infer that they all have these features after analysing only eight species. “The data represent more of a starting point for future investigations aimed at resolving the evolutionary origins of these confusing elements,” he says. Richard Essner of Southern Illinois University feels similarly. He recommends analysing tailed frogs and New Zealand frogs, because they branched off from other frogs 200 million years ago. If they too have fibrous kneecaps, it would reinforce the argument that the earliest frogs had them too, he says.
Hajszan T.,Yale University |
Hajszan T.,Hungarian Academy of Sciences |
Szigeti-Buck K.,Yale University |
Sallam N.L.,Yale University |
And 5 more authors.
Biological Psychiatry | Year: 2010
Background: Despite the fact that women are twice as likely to develop depression as men, our understanding of depression neurobiology in female subjects is limited. We have recently reported in male rats that development of helpless behavior is associated with a severe loss of hippocampal spine synapses, which is reversed by treatment with the antidepressant desipramine. Considering that estradiol has a hippocampal synaptogenic effect similar to those of antidepressants, the presence of estradiol during the female reproductive life might influence behavioral and synaptic responses to stress and depression. Methods: With electron microscopic stereology, we analyzed hippocampal spine synapses in association with helpless behavior in ovariectomized female rats (n = 70), under different conditions of estradiol exposure. Results: Stress induced an acute and persistent loss of hippocampal spine synapses, whereas subchronic treatment with desipramine reversed the stress-induced synaptic loss. Estradiol supplementation given either before stress or before escape testing of nonstressed animals increased the number of hippocampal spine synapses. Correlation analysis demonstrated a statistically significant negative correlation between the severity of helpless behavior and hippocampal spine synapse numbers. Conclusions: These findings suggest that hippocampal spine synapse remodeling might be a critical factor underlying learned helplessness and, possibly, the neurobiology of depression. © 2010 Society of Biological Psychiatry.
Otten A.M.,Public Health Agency of Canada |
Reid-Smith R.J.,University of Guelph |
Fazil A.,Ontario Veterinary College |
Weese J.S.,Public Health Agency of Canada
Epidemiology and Infection | Year: 2010
Participating researchers and public health personnel at a Canadian workshop in 2007, noted considerable gaps in current understanding of community-associated Clostridium difficile infection (CA-CDI), specifically infection sources and risk factors. A disease transmission model for CA-CDI was requested as an initial step towards a risk assessment, to analyse infection sources and risk factors, addressing priority research areas. The developed model contains eight infection states (susceptible, gastrointestinal exposure, colonized, diseased, deceased, clinically resolved colonized, relapse diseased, and cleared) and notes directional transfers between the states. Most published research used focused on hospital-associated C. difficile infection (HA-CDI) and further studies are needed to substantiate the use of HA-CDI knowledge in the transmission of CA-CDI. The aim was to provide a consistent framework for researchers, and provide a theoretical basis for future quantitative risk assessment of CA-CDI. Copyright © 2009 Cambridge University Press.
Keithlin J.,University of Guelph |
Keithlin J.,Ontario Veterinary College |
Sargeant J.,University of Guelph |
Sargeant J.,Ontario Veterinary College |
And 2 more authors.
Foodborne Pathogens and Disease | Year: 2014
Objective: This was a systematic review and meta-analysis to determine the proportion of Escherichia coli O157 cases that develop chronic sequelae. Data Sources: We conducted a systematic review of articles published prior to July 2011 in Pubmed, Agricola, CabDirect, or Food Safety and Technology Abstracts. Study Selection: Studies were selected that reported the number of E. coli O157 cases that developed reactive arthritis (ReA), hemolytic uremic syndrome (HUS), irritable bowel syndrome, inflammatory bowel disease, or Guillain Barré syndrome. Methods: Three levels of screening and data extraction of articles were conducted using predefined data fields. Meta-analysis was performed on unique outcome measures using a random-effects model, and heterogeneity was assessed using the I2 value. Meta-regression was used to explore the influence of nine study-level variables on heterogeneity. Results: A total of 82 studies were identified reporting 141 different outcome measures; 81 reported on HUS and one reported on ReA. Depending on the number of cases of E. coli O157, the estimate for the proportion of E. coli O157 cases that develop HUS ranged from 17.2% in extra-small studies (<50 cases) to 4.2% in extra-large studies (>1000 cases). Heterogeneity was significantly associated with group size (p<0.0001); however, the majority of the heterogeneity was unexplained. Conclusions: High unexplained heterogeneity indicated that the study-level factors examined had a minimal influence on the variation of estimates reported. © Mary Ann Liebert, Inc.
McIlwraith C.W.,Colorado State University |
Frisbie D.D.,Colorado State University |
Kawcak C.E.,Colorado State University |
Fuller C.J.,University of Bristol |
And 2 more authors.
Osteoarthritis and Cartilage | Year: 2010
Objective: Equine models of osteoarthritis (OA) have been used to investigate pathogenic pathways of OA and evaluate therapeutic candidates for naturally occurring equine OA which is a significant clinical disease in the horse. This review focuses on the macroscopic and microscopic criteria for assessing naturally occurring OA in the equine metacarpophalangeal joint as well as the osteochondral fragment-exercise model of OA in the equine middle carpal joint. Methods: A review was conducted of all published OA studies using horses and the most common macroscopic and microscopic scoring systems were summarized. Recommendations regarding methods of OA assessment in the horse have been made based on published studies. Results: A modified Mankin scoring system is recommended for semi-quantitative histological assessment of OA in horses due to its already widespread use and similarity to other scoring systems. Recommendations are also provided for histological scoring of synovitis and macroscopic lesions of OA as well as changes in the calcified cartilage and subchondral bone of naturally occurring OA. Conclusions: The proposed system for assessment of equine articular tissues provides a useful method to quantify OA change. It is believed that addition of quantitative tracing onto plastic and macroscopic measurement as recently described would be an improvement for overall assessment of articular cartilage change. © 2010 Osteoarthritis Research Society International.
Smadi H.,University of Guelph |
Smadi H.,McMaster University |
Sargeant J.M.,University of Guelph |
Sargeant J.M.,Ontario Veterinary College
Risk Analysis | Year: 2013
The current quantitative risk assessment model followed the framework proposed by the Codex Alimentarius to provide an estimate of the risk of human salmonellosis due to consumption of chicken breasts which were bought from Canadian retail stores and prepared in Canadian domestic kitchens. The model simulated the level of Salmonella contamination on chicken breasts throughout the retail-to-table pathway. The model used Canadian input parameter values, where available, to represent risk of salmonellosis. From retail until consumption, changes in the concentration of Salmonella on each chicken breast were modeled using equations for growth and inactivation. The model predicted an average of 318 cases of salmonellosis per 100,000 consumers per year. Potential reasons for this overestimation were discussed. A sensitivity analysis showed that concentration of Salmonella on chicken breasts at retail and food hygienic practices in private kitchens such as cross-contamination due to not washing cutting boards (or utensils) and hands after handling raw meat along with inadequate cooking contributed most significantly to the risk of human salmonellosis. The outcome from this model emphasizes that responsibility for protection from Salmonella hazard on chicken breasts is a shared responsibility. Data needed for a comprehensive Canadian Salmonella risk assessment were identified for future research. © 2012 Society for Risk Analysis.
Selokar N.L.,Ontario Veterinary College |
Selokar N.L.,National Dairy Research Institute |
St. John L.,Ontario Veterinary College |
Revay T.,Ontario Veterinary College |
And 3 more authors.
Cellular Reprogramming | Year: 2013
In this study, we tested the effects of valproic acid (VPA), a known histone deacetylase inhibitor (HDACi), on the growth characteristics, apoptosis, and cell cycle stages distribution of donor cells, as well as cloning efficiency, embryo development, and histone methylation. Our results showed that treatment of donor cells with VPA (2.5 mM, 5.0 mM, 7.5 mM, or 10 mM) for 24 h resulted in altered cell proliferation, extent of apoptosis and necrosis, and cell cycle stage distribution, whereas no changes in cell viability and chromosomal complements were observed. Measurement of relative gene expression using real-time PCR of a few developmentally important genes in treated donor cells showed decreased expression of HDAC1 and increased expression of BAX (p<0.05). No change in relative expression of HDAC2 and Bcl2 was noticed. Treatment of donor cells with VPA for 24 h before electrofusion significantly (p<0.05) increased the blastocyst formation rate of somatic cell nuclear transfer (SCNT) embryos compared to the control embryos. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive nuclei in SCNT blastocysts derived from VPA-treated donor cells were significantly decreased compared to the control blastocysts (p<0.05). Immunolocalization studies revealed that the levels of histone H3 at lysine 9 (H3K9me3) were lower in VPA-treated donor cells derived cloned blastocysts than nontreated cloned embryos, and was at the level of in vitro fertilization (IVF) counterparts, although no effects of treatments were found in donor cells. Our study demonstrates that the use of VPA in SCNT has been beneficial for efficient reprogramming of donor cells. Its effect on histone methylation in cloned embryos correlates with their developmental potential and may be a useful epigenetic marker to predict the efficiency of SCNT. © 2013, Mary Ann Liebert, Inc.
King N.,Ontario Veterinary College |
Dewey C.,Ontario Veterinary College |
Dewey C.,University of Guelph |
Borish D.,Ontario Veterinary College
PLoS ONE | Year: 2015
Background: Education is a key element in the socioeconomic development required to improve quality of life in Kenya. Despite the introduction of free primary education, primary school enrollment and attendance levels remain low. Drawing on qualitative and quantitative data, this study explores the determinants of non-enrollment and absenteeism in rural western Kenya and potential mitigation strategies to address these issues. Methods: The study was conducted in Bwaliro village in rural western Kenya. A random sample of 64 students was obtained by blocking the village primary school's student population according to grade level, gender, and orphan status. Qualitative and quantitative data were collected through interviews with parents, guardians, and key informants, and focus group discussions with students. Quantitative data were compared using chi-square tests, Student's T-test, and Poisson regressions. Qualitative data were analyzed using thematic content analysis. Results: Malaria, menstruation, and lack of money were among the most notable determinants of primary school dropout and absenteeism, and these factors disproportionately impacted orphans and female students. Potential mitigation strategies suggested by the community included provision of malaria treatment or prevention, reduction in education costs, expansion of the established school-feeding program, and provision of sanitary pads. Conclusion: Despite free primary education, numerous factors continue to prevent children in rural western Kenya from attending primary school. The findings suggest that interventions should primarily target orphaned and female students. Prior to implementation, suggested mitigation strategies should be assessed for cost-effectiveness. © 2015 King et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Meehan M.P.,Ontario Veterinary College |
Menniti M.F.,University of Guelph
Journal of Veterinary Medical Education | Year: 2014
Veterinary graduates require effective communication skills training to successfully transition from university into practice. Although the literature has supported the need for veterinary student communication skills training programs, there is minimal research using learning theory to design programs and explore students' perceptions of such programs. This study investigated veterinary students' perceptions of (I) their communication skills and (2) the usefulness of a communication skills training program designed with Kolb's Experiential Learning Theory (ELT) as a framework and implemented in a primary care setting. Twenty-nine final-year veterinary students from the Ontario Veterinary College attended a 3-Week communication skills training rotation. Pre- and post-training surveys explored their communication objectives, confidence in their communication skills, and the usefulness of specific communication training strategies. The results indicated that both before and after training, students were most confident in building rapport, displaying empathy, recognizing how bonded a client is with his or her pet, and listening. They were least confident in managing clients who were angry or not happy with the charges and who monopolized the appointment. Emotionally laden topics, such as breaking bad news and managing euthanasia discussions, were also identified as challenging and in need of improvement Interactive small-group discussions and review of video-recorded authentic client appointments were most valuable for their learning and informed students' self-awareness of their non-verbal communication. These findings support the use of Kolb's ELT as a theoretical framework and of video review and reflection to guide veterinary students' learning of communication skills in a primary care setting. © 2014 AAVMC.
Mackenzie S.D.,Ontario Veterinary College |
Caswell J.L.,Ontario Veterinary College |
Brisson B.A.,Ontario Veterinary College |
Gaitero L.,Ontario Veterinary College |
Chalmers H.J.,Ontario Veterinary College
Veterinary Radiology and Ultrasound | Year: 2014
A minimally invasive method for delivering injectable therapeutic agents would be desirable for the treatment of intervertebral disc disease in dogs. The purpose of this study was to compare computed tomography (CT), ultrasonography (US), and fluoroscopy modalities for guiding percutaneous injection into canine intervertebral discs. Intervertebral discs of 14 dog cadavers were injected with a gelified ethanol therapeutic agent. Successful injectate placement and injectate leakage were determined based on necropsy inspection of discs. Injection into the nucleus pulposus was successful in 55 of 78 (71%) of all injected discs. Injections guided using CT and fluoroscopy were significantly more successful than US-guided injections. Odds of successful injection without leakage were greater for CT vs. US (P = 0.0026) but there was no significant difference between CT and fluoroscopy (P = 0.0620). Injection success rates did not differ among vertebral sites or dog cadavers of varying weights. Forty-nine (63%) of injection sites had injectate leakage outside the disc and 10 of these involved structures within the vertebral canal. The highest rate of injection success with the least amount of leakage was achieved with CT guidance. Findings indicated that CT, fluoroscopy, and US are feasible modalities for guiding percutaneous injection of a gelified ethanol therapeutic agent into the canine intervertebral disc, with moderate to high success rates for different regions of the spine. However, a moderately high rate of injectate leakage occurred outside of the disc and this should be taken into consideration for future safety and efficacy studies. © 2014 American College of Veterinary Radiology.