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.

Reconstructing Native American population history

Abstract: The peopling of the Americas has been the subject of extensive genetic, archaeological and linguistic research; however, central questions remain unresolved. One contentious issue is whether the settlement occurred by means of a single migration or multiple streams of migration from Siberia. The pattern of dispersals within the Americas is also poorly understood. To address these questions at a higher resolution than was previously possible, we assembled data from 52 Native American and 17 Siberian groups genotyped at 364,470 single nucleotide polymorphisms. Here we show that Native Americans descend from at least three streams of Asian gene flow. Most descend entirely from a single ancestral population that we call 'First American'. However, speakers of Eskimo-Aleut languages from the Arctic inherit almost half their ancestry from a second stream of Asian gene flow, and the Na-Dene-speaking Chipewyan from Canada inherit roughly one-tenth of their ancestry from a third stream. We show that the initial peopling followed a southward expansion facilitated by the coast, with sequential population splits and little gene flow after divergence, especially in South America. A major exception is in Chibchan speakers on both sides of the Panama isthmus, who have ancestry from both North and South America.

Learning hatching for pen-and-ink illustration of surfaces

Abstract: This article presents an algorithm for learning hatching styles from line drawings. An artist draws a single hatching illustration of a 3D object. Her strokes are analyzed to extract the following per-pixel properties: hatching level (hatching, cross-hatching, or no strokes), stroke orientation, spacing, intensity, length, and thickness. A mapping is learned from input geometric, contextual, and shading features of the 3D object to these hatching properties, using classification, regression, and clustering techniques. Then, a new illustration can be generated in the artist's style, as follows. First, given a new view of a 3D object, the learned mapping is applied to synthesize target stroke properties for each pixel. A new illustration is then generated by synthesizing hatching strokes according to the target properties.

Cardiac outcomes after screening for asymptomatic coronary artery disease in patients with type 2 diabetes: the DIAD study: a randomized controlled trial.

Abstract: Context Coronary artery disease (CAD) is the major cause of mortality and morbidity in patients with type 2 diabetes. But the utility of screening patients with type 2 diabetes for asymptomatic CAD is controversial. Objective To assess whether routine screening for CAD identifies patients with type 2 diabetes as being at high cardiac risk and whether it affects their cardiac outcomes. Design, Setting, and Patients The Detection of Ischemia in Asymptomatic Diabetics (DIAD) study is a randomized controlled trial in which 1123 participants with type 2 diabetes and no symptoms of CAD were randomly assigned to be screened with adenosine-stress radionuclide myocardial perfusion imaging (MPI) or not to be screened. Participants were recruited from diabetes clinics and practices and prospectively followed up from August 2000 to September 2007. Main Outcome Measure Cardiac death or nonfatal myocardial infarction (MI). Results The cumulative cardiac event rate was 2.9% over a mean (SD) follow-up of 4.8 (0.9) years for an average of 0.6% per year. Seven nonfatal MIs and 8 cardiac deaths (2.7%) occurred among the screened group and 10 nonfatal MIs and 7 cardiac deaths (3.0%) among the not-screened group (hazard ratio [HR], 0.88; 95% confidence interval [CI], 0.44-1.88; P = .73). Of those in the screened group, 409 participants with normal results and 50 with small MPI defects had lower event rates than the 33 with moderate or large MPI defects; 0.4% per year vs 2.4% per year (HR, 6.3; 95% CI, 1.9-20.1; P = .001). Nevertheless, the positive predictive value of having moderate or large MPI defects was only 12%. The overall rate of coronary revascularization was low in both groups: 31 (5.5%) in the screened group and 44 (7.8%) in the unscreened group (HR, 0.71; 95% CI, 0.45-1.1; P = .14). During the course of study there was a significant and equivalent increase in primary medical prevention in both groups. Conclusion In this contemporary study population of patients with diabetes, the cardiac event rates were low and were not significantly reduced by MPI screening for myocardial ischemia over 4.8 years. Trial Registration clinicaltrials.gov Identifier: NCT00769275

Frataxin is Reduced in Friedreich Ataxia Patients and is Associated with Mitochondrial Membranes

Abstract: Friedreich ataxia is a progressive neurodegenerative disorder caused by loss of function mutations in the frataxin gene. In order to unravel frataxin function we developed monoclonal antibodies raised against different regions of the protein. These antibodies detect a processed 18 kDa protein in various human and mouse tissues and cell lines that is severely reduced in Friedreich ataxia patients. By immunocytofluorescence and immunocytoelectron microscopy we show that frataxin is located in mitochondria, associated with the mitochondrial membranes and crests. Analysis of cellular localization of various truncated forms of frataxin expressed in cultured cells and evidence of removal of an N-terminal epitope during protein maturation demonstrated that the mitochondrial targetting sequence is encoded by the first 20 amino acids. Given the shared clinical features between Friedreich ataxia, vitamin E deficiency and some mitochondriopathies, our data suggest that a reduction in frataxin results in oxidative damage.