Université de Montréal

About: Université de Montréal is a education organization based out in Montreal, Quebec, Canada. It is known for research contribution in the topics: Population & Poison control. The organization has 45641 authors who have published 100476 publications receiving 4004007 citations. The organization is also known as: University of Montreal & UdeM.

Oral Contraceptives and the Risk of Hereditary Ovarian Cancer

Abstract: Background Women with mutations in either the BRCA1 or the BRCA2 gene have a high lifetime risk of ovarian cancer. Oral contraceptives protect against ovarian cancer in general, but it is not known whether they also protect against hereditary forms of ovarian cancer. Methods We enrolled 207 women with hereditary ovarian cancer and 161 of their sisters as controls in a case–control study. All the patients carried a pathogenic mutation in either BRCA1 (179 women) or BRCA2 (28 women). The control women were enrolled regardless of whether or not they had either mutation. Lifetime histories of oral-contraceptive use were obtained by interview or by written questionnaire and were compared between patients and control women, after adjustment for year of birth and parity. Results The adjusted odds ratio for ovarian cancer associated with any past use of oral contraceptives was 0.5 (95 percent confidence interval, 0.3 to 0.8). The risk decreased with increasing duration of use (P for trend, <0.001); use for six or...

Characterizing the profile of obese patients who are metabolically healthy

Abstract: The presence of obesity-related metabolic disturbances varies widely among obese individuals. Accordingly, a unique subset of obese individuals has been described in the medical literature, which seems to be protected or more resistant to the development of metabolic abnormalities associated with obesity. These individuals, now known as 'metabolically healthy but obese' (MHO), despite having excessive body fatness, display a favorable metabolic profile characterized by high levels of insulin sensitivity, no hypertension as well as a favorable lipid, inflammation, hormonal, liver enzyme and immune profile. However, recent studies have indicated that this healthier metabolic profile may not translate into a lower risk for mortality. Mechanisms that could explain the favorable metabolic profile of MHO individuals are poorly understood. However, preliminary evidence suggests that differences in visceral fat accumulation, birth weight, adipose cell size and gene expression-encoding markers of adipose cell differentiation may favor the development of the MHO phenotype. Despite the uncertainty regarding the exact degree of protection related to the MHO status, identification of underlying factors and mechanisms associated with this phenotype will eventually be invaluable in helping us understand factors that predispose, delay or protect obese individuals from metabolic disturbances. Collectively, a greater understanding of the MHO individual has important implications for therapeutic decision making, the characterization of subjects in research protocols and medical education.

REM sleep behavior disorder and REM sleep without atonia in Parkinson's disease.

Abstract: Objective: To determine the frequency of REM sleep behavior disorder (RBD) among patients with PD using both history and polysomnography (PSG) recordings and to further study REM sleep muscle atonia in PD. Background: The reported occurrence of RBD in PD varies from 15 to 47%. However, no study has estimated the frequency of RBD using PSG recordings or analyzed in detail the characteristics of REM sleep muscle atonia in a large group of unselected patients with PD. Methods: Consecutive patients with PD (n = 33) and healthy control subjects (n = 16) were studied. Each subject underwent a structured clinical interview and PSG recording. REM sleep was scored using a method that allows the scoring of REM sleep without atonia. Results: One third of patients with PD met the diagnostic criteria of RBD based on PSG recordings. Only one half of these cases would have been detected by history. Nineteen (58%) of 33 patients with PD but only 1 of 16 control subjects had REM sleep without atonia. Of these 19 patients with PD, 8 (42%) did not present with behavioral manifestations of RBD, and their cases may represent preclinical forms of RBD associated with PD. Moreover, the percentage of time spent with muscle atonia during REM sleep was lower among patients with PD than among healthy control subjects (60.1% vs 93.2%; p = 0.003). Conclusions: RBD and REM sleep without atonia are frequent in PD as shown by PSG recordings.

Plasma sterilization. Methods and mechanisms

Abstract: Utilizing a plasma to achieve sterilization is a possible alternative to conventional sterilization means as far as sterilization of heat-sensitive materials and innocuity of steriliz- ing agents are concerned. A major issue of plasma sterilization is the respective roles of ultra- violet (UV) photons and reactive species such as atomic and molecular radicals. At reduced gas pressure (≤10 torr) and in mixtures containing oxygen, the UV photons dominate the inactivation process, with a significant contribution of oxygen atoms as an erosion agent. Actually, as erosion of the spore progresses, the number of UV photons successfully inter- acting with the genetic material increases. The different physicochemical processes at play during plasma sterilization are identified and analyzed, based on the specific characteristics of the spore survival curves.

The nitrogen : phosphorus relationship in lakes

Abstract: Published data on mean annual epilimnetic total N (TN) and P (TP) were analyzed to find how TN : TP varies with lake trophic status. TN : TP is high in oligotrophic lakes and very low in eutrophic lakes, declining in a curvilinear fashion with increased TP. Comparison of this trend with published N : P in lake nutrient sources suggests that TN : TP reflects the source of nutrients: the ratio is high in oligotrophic lakes because they receive their N and P from natural, undisturbed watersheds which export much less P than N; mesotrophic and eutrophic lakes receive various mixtures of nutrient sources that have lower average N : P, and very eutrophic lakes have N : P that correspond very nearly to the N : P of sewage. Two inflection points were identified in the TN : TP relationship (-20 and - 100 wg TP liter-l) the first probably reflecting the large difference between TN : TP in nutrient export from undisturbed terrestrial ecosystems and that of meso- and eutrophic sources such as urban and pasture land runoff and sewage, and the second probably reflecting increased rates of denitrification in eutrophic lakes. Analysis of published manipulation experiments shows that N limitation is not only significantly more frequent in lakes of low ambient TN: TP (TN: TP mass ratio 5 14) but is also significantly more frequent in lakes with TP > 30 wg liter’.