Showing papers by "Université de Sherbrooke published in 2004"

Clostridium difficile-associated diarrhea in a region of Quebec from 1991 to 2003: a changing pattern of disease severity

Abstract: Background: Recent reports suggest that Clostridium difficile colitis may be evolving into a more severe disease. During the second half of 2002 we noted an increase in the number of patients with severe C. difficile -associated diarrhea (CDAD) in our institution. We describe cases of CDAD at our institution over a 13-year period and investigate changes in illness severity. Methods: We undertook a retrospective chart review of all cases of CDAD diagnosed at the Centre hospitalier universitaire de Sherbrooke from Jan. 1, 1991, to Dec. 31, 2003. Because the hospital serves a well-defined population of Quebec, we were also able to calculate population-based incidence during this period. We abstracted data on individual patients from patient charts and from hospital and pharmacy computer databases. We defined cases of CDAD as having a positive C. difficile cytotoxicity assay result, or endoscopic or histopathological evidence of pseudomembranous colitis. A case was considered complicated if one or more of the following was observed: megacolon, perforation, colectomy, shock requiring vasopressor therapy, or death within 30 days after diagnosis. Results: A total of 1721 cases of CDAD were diagnosed during the study period. The incidence increased from 35.6 per 100 000 population in 1991 to 156.3 per 100 000 in 2003; among patients aged 65 years or more, it increased from 102.0 to 866.5 per 100 000. The proportion of cases that were complicated increased from 7.1% (12/169) in 1991–1992 to 18.2% (71/390) in 2003 ( p p 9 /L or greater) and an elevated creatinine level (200 μmol/L or greater) were strongly associated with adverse outcomes: in 2003, 45 (40.9%) of 110 patients with a high leukocyte count or creatinine level, or both, had complicated CDAD and 28 (25.5%) died within 30 days after diagnosis. After adjustment for age and other confounding factors, patients initially given oral vancomycin therapy had a risk of progression to complicated CDAD that was 79% lower than the risk among patients initially treated with metronidazole (adjusted odds ratio 0.2, 95% confidence interval 0.06–0.8, p = 0.02). Interpretation: An epidemic of CDAD with an increased case-fatality rate has had important consequences on the elderly population of our region. Our observational data suggest that the equivalence of vancomycin and metronidazole in the treatment of CDAD needs to be questioned.

Multimorbidity and quality of life in primary care: a systematic review

Abstract: Background Many patients with several concurrent medical conditions (multimorbidity) are seen in the primary care setting. A thorough understanding of outcomes associated with multimorbidity would benefit primary care workers of all disciplines. The purpose of this systematic review was to clarify the relationship between the presence of multimorbidity and the quality of life (QOL) or health-related quality of life (HRQOL) of patients seen, or likely to be seen, in the primary care setting.

DNA strand breaks induced by 0-4 eV electrons: the role of shape resonances.

Abstract: Collisions of 0--4 eV electrons with thin DNA films are shown to produce single strand breaks. The yield is sharply structured as a function of electron energy and indicates the involvement of ${\ensuremath{\pi}}^{*}$ shape resonances in the bond breaking process. The cross sections are comparable in magnitude to those observed in other compounds in the gas phase in which ${\ensuremath{\pi}}^{*}$ electrons are transferred through the molecule to break a remote bond. The results therefore support aspects of a theoretical study by Barrios et al. [J. Phys. B 106, 7991 (2002)] indicating that such a mechanism could produce strand breaks in DNA.

REVIEW: The management of wild large herbivores to meet economic, conservation and environmental objectives

Abstract: Summary 1. Wild large herbivores provide goods and income to rural communities, have major impacts on land use and habitats of conservation importance and, in some cases, face local or global extinction. As a result, substantial effort is applied to their management across the globe. To be effective, however, management has to be science-based. We reviewed recent fundamental and applied studies of large herbivores with particular emphasis on the relationship between the spatial and temporal scales of ecosystem response, management decision and implementation. 2. Long-term population dynamics research has revealed fundamental differences in how sex/age classes are affected by changes in density and weather. Consequently, management must be tailored to the age and sex structure of the population, rather than to simple population counts. 3. Herbivory by large ungulates shapes the structure, diversity and functioning of most terrestrial ecosystems. Recent research has shown that fundamental herbivore/vegetation interactions driving landscape change are localized, often at scales of a few metres. For example, sheep and deer will selectively browse heather Calluna vulgaris at the edge of preferred grass patches in heather moorland. As heather is vulnerable to heavy defoliation, in the long term this can lead to loss of heather cover despite the average utilization rate of heather in a management area being low. Therefore, while herbivore population management requires a large-scale approach, management of herbivore impacts on vegetation may require a much more flexible and site-specific approach. 4. Localized impacts on vegetation have cascading effects on biodiversity, because changes in vegetation structure and composition, induced by large herbivores affect habitat suitability for many other species. As such, grazing should be considered as a tool for broader biodiversity management requiring a more sophisticated approach than just, for example, eliminating grazing from conservation areas through the use of exclosures. 5. Synthesis and applications . The management of wild large herbivores must consider different spatial scales, from small patches of vegetation to boundaries of an animal population. It also requires long-term planning based on a deep understanding of how population processes, such a birth rate, death rate and age structure, are affected by changes in land use and climate and how these affect localized herbivore impacts. Because wild herbivores do not observe administrative or political boundaries, adjusting their management to socio-political realities can present a challenge. Many developing countries have established co-operative management groups that allow all interested parties to be involved in the development of management plans; developed countries have a lot to learn from the developing world’s example.

Preparation of Azobenzene-Containing Amphiphilic Diblock Copolymers for Light-Responsive Micellar Aggregates

Abstract: Diblock copolymers composed of a side-chain liquid crystalline azobenzene-containing polymethacrylate and poly(tert-butyl acrylate) (PAzoMA-b-PtBA) were prepared using atom-transfer radical polymerization (ATRP). After subsequent selective hydrolysis of PtBA yielding poly(acrylic acid) (PAA), amphiphilic diblock copolymers of PAzoMA-b-PAA were obtained. Aggregation of either PAzoMA or PAA block occurs in solvents selective for one of the blocks. Adding water into dioxane solution of PAzoMA-b-PAA forms micellar aggregates due to the hydrophobic PAzoMA block. Under alternating UV and visible light illumination, reversible changes in micellar aggregates, for both core-shell micelles and vesicles, took place as a result of the reversible trans-cis photoisomerization of azobenzene mesogens in PAzoMA.

Mutations in ARFGEF2 implicate vesicle trafficking in neural progenitor proliferation and migration in the human cerebral cortex

Abstract: Mutations in ARFGEF2 implicate vesicle trafficking in neural progenitor proliferation and migration in the human cerebral cortex

Image Retrieval from the World Wide Web: Issues, Techniques, and Systems

Abstract: With the explosive growth of the World Wide Web, the public is gaining access to massive amounts of information. However, locating needed and relevant information remains a difficult task, whether the information is textual or visual. Text search engines have existed for some years now and have achieved a certain degree of success. However, despite the large number of images available on the Web, image search engines are still rare. In this article, we show that in order to allow people to profit from all this visual information, there is a need to develop tools that help them to locate the needed images with good precision in a reasonable time, and that such tools are useful for many applications and purposes. The article surveys the main characteristics of the existing systems most often cited in the literature, such as ImageRover, WebSeek, Diogenes, and Atlas WISE. It then examines the various issues related to the design and implementation of a Web image search engine, such as data gathering and digestion, indexing, query specification, retrieval and similarity, Web coverage, and performance evaluation. A general discussion is given for each of these issues, with examples of the ways they are addressed by existing engines, and 130 related references are given. Some concluding remarks and directions for future research are also presented.

Design, synthesis, and biological evaluation of the first selective nonpeptide AT2 receptor agonist.

Abstract: The first druglike selective angiotensin II AT(2) receptor agonist (21) with a K(i) value of 0.4 nM for the AT(2) receptor and a K(i) > 10 microM for the AT(1) receptor is reported. Compound 21, with a bioavailability of 20-30% after oral administration and a half-life estimated to 4 h in rat, induces outgrowth of neurite cells, stimulates p42/p44(mapk), enhances in vivo duodenal alkaline secretion in Sprague-Dawley rats, and lowers the mean arterial blood pressure in anesthetized, spontaneously hypertensive rats. Thus, the peptidomimetic 21 exerts a similar biological response as the endogenous peptide angiotensin II after selective activation of the AT(2) receptor. Compound 21, derived from the prototype nonselective AT(1)/AT(2) receptor agonist L-162,313 will serve as a valuable research tool, enabling studies of the function of the AT(2) receptor in more detail.

Studies of the Hydrogen Evolution Reaction on Raney Nickel—Molybdenum Electrodes

Abstract: The hydrogen evolution reaction was studied in 1 M KOH at 25 °C on two types of electrodes:(i) pressed powders of Ni or NiMo with Al, heated at 700 °C; (ii) Ni—Al—Mo powders deposited by vacuum plasma spraying. These materials were treated with alkaline solution to leach out aluminum. Very active and stable Raney nickel—molybdenum electrodes were obtained from Al rich alloys. Adding molybdenum significantly improved catalytic activity. Electrochemical impedance spectroscopy was used to determine the apparent and intrinsic activities. Different ac models were tested and the appropriate one was selected. Intrinsic activities of these electrodes are smaller or equal to that of polycrystalline Ni and the origin of high apparent activities is related to the increase in real surface area.

Signal transduction and functional changes in neutrophils with aging

Abstract: It is well known that the immune response decreases during aging, leading to a higher susceptibility to infections, cancers and autoimmune disorders Most widely studied have been alterations in the adaptive immune response Recently, the role of the innate immune response as a first-line defence against bacterial invasion and as a modulator of the adaptive immune response has become more widely recognized One of the most important cell components of the innate response is neutrophils and it is therefore important to elucidate their function during aging With aging there is an alteration of the receptor-driven functions of human neutrophils, such as superoxide anion production, chemotaxis and apoptosis One of the alterations underlying these functional changes is a decrease in signalling elicited by specific receptors Alterations were also found in the neutrophil membrane lipid rafts These alterations in neutrophil functions and signal transduction that occur during aging might contribute to the significant increase in infections in old age

Complications of tension-free vaginal tape surgery: a multi-institutional review.

Abstract: OBJECTIVE To analyse the complications of tension-free vaginal tape (TVT) surgery, a minimally invasive alternative for treating patients with stress urinary incontinence (SUI), at six institutions, and to review the management of these complications and their effect on patient outcome. PATIENTS AND METHODS In all, 241 patients who had a TVT procedure by six urologists at six hospitals (two university and four community) were reviewed retrospectively by the same urologist. Complications during and after surgery, and their management, were analysed. RESULTS Complications during surgery included bladder perforation in 48 patients (5.8%) and blood loss > 500 mL in 16 (2.5%). Immediate complications after surgery were urinary retention (>24 h after) in 47 patients (19.7%), pelvic haematoma in four (1.9%) and suprapubic wound infection in one (0.4%). Of the 47 patients in retention, 32 were in retention for <48 h and treated with an indwelling catheter. The 15 remaining patients were treated with an indwelling catheter (one) or clean intermittent catheterization for a mean of 22 days. To correct the retention the TVT was released in seven patients and the tape sectioned in three. Late complications were de novo urgency, persistent suprapubic discomfort and intravaginal tape erosion in 36 (15%), 18 (7.5%) and one (0.4%) patient, respectively. Most of these complications resolved with observation and medical management, but intravaginal tape erosion required partial resection of the tape with closure and repair of the vaginal mucosa. CONCLUSIONS The present TVT complication rates were slightly higher than reported previously. This multi-institutional review in both academic and community hospitals may better reflect the morbidity of TVT insertion in clinical practice. TVT is a highly effective, minimally invasive method for treating SUI. A stricter definition of each complication and a better understanding of the mechanism of these complications may further improve the surgical outcome and decrease patient morbidity.

Transient DNA Strand Breaks During Mouse and Human Spermiogenesis:New Insights in Stage Specificity and Link to Chromatin Remodeling

Abstract: In the course of mammalian spermiogenesis, a unique chromatin remodeling process takes place within elongating and condensing spermatid nuclei. The histone-to-protamine exchange results in efficient packaging and increased stability of the paternal genome. Although not fully understood, this change in chromatin architecture must require a global but transient appearance of endogenous DNA strand breaks because most of the DNA supercoiling is eliminated in the mature sperm. To establish the extent of DNA strand breakage and the stage specificity at which these breaks are created and repaired, we performed a sensitive terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) assay to detect in situ DNA strand breaks on both mice and human testis cross sections. In the mouse, we established that DNA strand breaks are indeed detected in the whole population of elongating spermatids between stages IX and XI of the seminiferous epithelium cycle perfectly coincident with the chromatin remodeling as revealed by histone H4 hyperacetylation. Similarly, TUNEL analyses performed on human testis sections revealed an elevated and global increase in the levels of DNA strand breaks present in nuclei of round-shaped spermatids also coincident with chromatin remodeling. The demonstration of the global character of the transient DNA strand breaks in mammalian spermiogenesis suggests that deleterious consequences on genetic integrity of the male gamete may arise from any disturbance in the process. In addition, this investigation may shed some light on the origin of the low success rate that has been encountered so far with intracytoplasmic injection procedures making use of round spermatids in humans.

Comparison between the unscented Kalman filter and the extended Kalman filter for the position estimation module of an integrated navigation information system

Abstract: An integrated navigation information system must know continuously the current position with a good precision. The required performance of the positioning module is achieved by using a cluster of heterogeneous sensors whose measurements are fused. The most popular data fusion method for positioning problems is the extended Kalman filter. The extended Kalman filter is a variation of the Kalman filter used to solve non-linear problems. Recently, an improvement to the extended Kalman filter has been proposed, the unscented Kalman filter. This paper describes an empirical analysis evaluating the performances of the unscented Kalman filter and comparing them with the extended Kalman filter's performances.

σ Factors and Global Gene Regulation in Mycobacterium tuberculosis

Abstract: Tuberculosis remains a worldwide threat despite the availability of the BCG vaccine and antibiotic treatment. It is estimated that its etiologic agent, Mycobacterium tuberculosis , infects almost a third of the human population and kills two million people every year ([27][1]). The recent human

Measuring social participation: reliability of the LIFE-H in older adults with disabilities

Abstract: Purpose: Much more attention should be paid to instruments documenting social participation as this area is increasingly considered a pivotal outcome of a successful rehabilitation. The purpose of this study was to document the reliability of a participation measure, the Assessment of Life Habits (LIFE-H), in older adults with functional limitations.Methods: Eighty-four individuals with physical disabilities living in three different environments were assessed twice with the LIFE-H, an instrument that documents the quality of social participation by assessing a person's performance in daily activities and social roles (life habits).Results: The intraclass correlation coefficients (ICC) computed for intrarater reliability exceeded 0.75 for seven out of the 10 life habits categories. For interrater reliability, the total score and daily activities subscore are highly reliable (ICC ⩽ 0.89), and the social roles subscore is moderately reliable (ICC = 0.64). ‘Personal care’ is the category with the highest ICC...

Transactional sex is the driving force in the dynamics of HIV in Accra Ghana.

Abstract: OBJECTIVE: To delineate the population attributable fraction (PAF) of transactional sex in prevalent cases of HIV infection in the male adult population of Accra, Ghana. DESIGN AND METHODS: Cross-sectional study of clients who visited a sex worker (SW), of boyfriends of SW and of male personnel in prostitution venues. A questionnaire was administered and urine obtained for detection of anti-HIV antibodies. The PAF of prevalent HIV acquired from SW was calculated using a combination of data from this survey of clients, from on-going SW surveys, the national HIV surveillance system and the national census. RESULTS: HIV prevalence was 4.9% (8/162) among clients of mobile SW, 15.8% (53/335) among clients of home-based SW, 17.5% (10/57) among personnel and 32.1% (9/28) among boyfriends. A condom was used in 90% of intercourses, according to clients. Non-use of a condom was clustered in selected locations and independently associated with older age of client, frequency of intercourse with SW in the last year and current urethritis. Among the male population of Accra aged 15-59 years, 84% of prevalent cases of HIV were attributable to transactional sex. A sensitivity analysis showed that under various assumptions PAF varied between 47% and 100%. CONCLUSIONS: In Accra, approximately four-fifths of prevalent cases of HIV in adult males were acquired from SW. Comprehensive interventions providing education, condoms and treatment for sexually transmitted diseases for SW and their clients should be approached as other public health priorities and provided in all cities, large and small, of West Africa.

Toward the definition of cerebral arteriopathies of childhood.

Abstract: Purpose of review To facilitate and standardize the diagnosis of cerebrovascular conditions in childhood, particularly in the field of arterial ischemic diseases. Recent findings Progress in diagnostic techniques in the past decade have led to newly established etiologies for childhood stroke, most of which represent some form of vascular pathology. These advances must be integrated into a modern nomenclature system with revised definitions of stroke and arterial wall diseases-arteriopathies-in childhood. Summary This nomenclature system is intended to facilitate and enhance clinical research in childhood stroke, particularly multicenter collaborative studies.

Properties of LYSO and recent LSO scintillators for phoswich PET detectors

Abstract: The luminescence and nuclear spectroscopic properties of the new cerium-doped rare-earth scintillator lutetium-yttrium oxyorthosilicate (Lu/sub 0.6/Y/sub 1.4/Si/sub 0.5/:Ce, LYSO) were investigated and compared to those of both recent and older LSO crystals. UV-excited luminescent spectra outline important similarities between LYSO and LSO scintillators. The two distinct Ce1 and Ce2 luminescence mechanisms previously identified in LSO are also present in LYSO scintillators. The energy and timing resolutions were measured using avalanche photodiode (APD) and photomultiplier tube (PMT) readouts. The dependence of energy resolution on gamma-ray energy was also assessed to unveil the crystal intrinsic resolution parameters. In spite of significant progress in light output and luminescence properties, the energy resolution of these scintillators appears to still suffer from an excess variance in the number of scintillation photons. Pulse-shape discrimination between LYSO and LSO scintillators has been successfully achieved in phoswich assemblies, confirming LYSO, with a sufficient amount of yttrium to modify the decay time, to be a potential candidate for depth-of-interaction determination in multicrystal PET detectors.

Transition nuclear proteins are required for normal chromatin condensation and functional sperm development.

Abstract: Summary: The histone-to-protamine transition is important in the formation of spermatozoa. In mammals this involves two steps: replacement of histones by transition nuclear proteins (TPs) and replacement of TPs by protamines. To determine the functions of the TPs and their importance for sperm development, we generated mice lacking both TPs, since mice lacking only TP1 or TP2 were fertile. Our results indicated that TP1 and TP2 had partially complemented each other. In mice lacking both TPs, nuclear shaping, transcriptional repression, histone displacement, and protamine deposition proceeded relatively normally, but chromatin condensation was irregular in all spermatids, many late spermatids showed DNA breaks, and protamine 2 was not posttranslationally processed. Nevertheless, genomic integrity was maintained in mature spermatids, since efficient fertilization and production of offspring were achieved by intracytoplasmic sperm injection. However, many mature spermatids were retained in the testis, epididymal spermatozoa were drastically reduced in number and were highly abnormal, and the mice were sterile. Most epididymal spermatozoa were incapable of fertilization even using intracytoplasmic sperm injection. Thus, in mammals TPs are required for normal chromatin condensation, for reducing the number of DNA breaks, and for preventing the formation of secondary defects in spermatozoa, eventual loss of genomic integrity, and sterility. genesis 38:200–213, 2004. © 2004 Wiley-Liss, Inc.

Is social participation associated with quality of life of older adults with physical disabilities

Abstract: Purpose: To explore the relationships between subjective quality of life and social participation of older adults with physical disabilities.Method: A cross-sectional design was used with a convenience sample of 46 people aged 60 to 90 living in the community. Subjective quality of life was estimated with the Quality of Life Index and social participation with the Assessment of Life Habits.Results: Only a weak relationship was found between total scores of quality of life and social participation. Interpersonal relationships, responsibilities, fitness and recreation were the categories of social participation most associated with quality of life. Social roles were more associated with quality of life than daily activities. Finally, satisfaction with the accomplishment of life habits was also more associated with quality of life than the performance itself.Conclusions: The importance of social participation in regard to the quality of life of older persons with physical disabilities living in the community...

Climate forcing and density dependence in a mountain ungulate population

Abstract: Population models in ecology are rarely validated by comparing their pre- dictions to long-term observations of changes in population size. We have used a variety of analytical tools to examine a 45-year time series of annual censuses of Alpine ibex (Capra ibex) in the Gran Paradiso National Park in northwestern Italy. This ibex population grew from about 3300 to almost 5000 individuals in the 1980s during a decade of anom- alously mild winters, and then began to decline in the 1990s. By 1997, the population size had returned to previous levels. Adult survival apparently increased and adult sex ratio may have changed to slightly favor males during the increase in population density. Yearly changes in total population were correlated with seasonal average snow depth and population density over the 39 years for which climate data were available. Our results show that the ibex population size was limited by both density dependence and deep snow. A model based on these factors fit to the first 19 years of data was used to forecast subsequent changes in total population based on initial population size and yearly snow depth. The model was able to predict the increase and subsequent decline in total population size over the final 20 years of the study but failed to reproduce population levels after the eruption. Our results suggest that the 1980s episode of population growth was primarily driven by increased adult survival, rather than increased recruitment.

The effect of habitat quality on foraging patterns, provisioning rate and nestling growth in Corsican Blue Tits Parus caeruleus

Abstract: Many bird species face seasonal and spatial variation in the availability of the specific food required to rear chicks. Caterpillar availability is often identified as the most important factor determining chick quality and breeding success in forest birds, such as tits Parus spp. It is assumed that parents play an important role in mediating the effect of environment on chick development. A reduction in prey availability should therefore result in increased foraging effort to maintain the amount of food required for optimal chick development. To investigate the capacity of adults to compensate for a reduction in food supply, we compared the foraging behaviour of Blue Tits Parus caeruleus breeding in rich and poor habitats in Corsica. We monitored the foraging effort of adults using radiotelemetry. We also identified and quantified prey items provided to nestlings by using a video camera mounted on the nest. We found that the mean travelling distance of adults was twice as great in the poor habitat as it was in the rich. Despite the marked difference in foraging distance, the proportion of optimal prey (caterpillars) in the diet of the chicks and the total biomass per hour per chick did not differ between the two habitats. We argue that relationships between habitat richness, offspring quality and breeding success cannot be understood adequately without quantifying parental effort.

Polysaccharides : Structural Diversity and Functional Versatility, Second Edition

Abstract: Completely revised and expanded to reflect the latest advancements in the field, Polysaccharides: Structural Diversity and Functional Versatility, Second Edition outlines fundamental concepts in the structure, function, chemistry, and stability of polysaccharides and reveals new analytical techniques and applications currently impacting the cosmeti