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.

The origin and early evolution of mitochondria

Abstract: Complete sequences of numerous mitochondrial, many prokaryotic, and several nuclear genomes are now available. These data confirm that the mitochondrial genome originated from a eubacterial (specifically α-proteobacterial) ancestor but raise questions about the evolutionary antecedents of the mitochondrial proteome.

The Impact of Empowerment on Customer Contact Employees’ Roles in Service Organizations:

Abstract: A pilot study was conducted to test a hierarchical model in which empowerment of contact personnel is presented as an antecedent condition to role conflict, role ambiguity, adaptability, self-effic...

Species associations: the Kendall coefficient of concordance revisited

Abstract: The search for species associations is one of the classical problems of community ecology. This article proposes to use Kendall’s coefficient of concordance (W) to identify groups of significantly associated species in field survey data. An overall test of independence of all species is first carried out. If the null hypothesis is rejected, one looks for groups of correlated species and, within each group, tests the contribution of each species to the overall statistic, using a permutation test. A field survey of oribatid mites in the peat blanket surrounding a bog lake is presented as an example. In the permutation framework, an a posteriori test of the contribution of each “judge” (species) to the overall W concordance statistic is possible; this is not the case in the classical testing framework. A simulation study showed that when the number of judges is small, which is the case in most real-life applications of Kendall’s test of concordance, the classical χ2 test is overly conservative, whereas the permutation test has correct Type 1 error; power of the permutation test is thus also higher. The interpretation and usefulness of the a posteriori tests are discussed in the framework of environmental studies. They can help identify groups of concordant species that can be used as indices of the quality of the environment, in particular in cases of pollution or contamination of the environment.

HIV-1 Viremia Prevents the Establishment of Interleukin 2–producing HIV-specific Memory CD4+ T Cells Endowed with Proliferative Capacity

Abstract: CD4+ T cell responses are associated with disease control in chronic viral infections. We analyzed human immunodeficiency virus (HIV)-specific responses in ten aviremic and eight viremic patients treated during primary HIV-1 infection and for up to 6 yr thereafter. Using a highly sensitive 5-(and-6)-carboxyfluorescein diacetate-succinimidyl ester-based proliferation assay, we observed that proliferative Gag and Nef peptide-specific CD4+ T cell responses were 30-fold higher in the aviremic patients. Two subsets of HIV-specific memory CD4+ T cells were identified in aviremic patients, CD45RA- CCR7+ central memory cells (Tcm) producing exclusively interleukin (IL)-2, and CD45RA- CCR7- effector memory cells (Tem) that produced both IL-2 and interferon (IFN)-gamma. In contrast, in viremic, therapy-failing patients, we found significant frequencies of Tem that unexpectedly produced exclusively IFN-gamma. Longitudinal analysis of HIV epitope-specific CD4+ T cells revealed that only cells that had the capacity to produce IL-2 persisted as long-term memory cells. In viremic patients the presence of IFN-gamma-producing cells was restricted to periods of elevated viremia. These findings suggest that long-term CD4+ T cell memory depends on IL-2-producing CD4+ T cells and that IFN-gamma only-producing cells are short lived. Our data favor a model whereby competent HIV-specific Tcm continuously arise in small numbers but under persistent antigenemia are rapidly induced to differentiate into IFN-gamma only-producing cells that lack self-renewal capacity.