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Yamashita S.,University of Iowa | Tai P.,University of Iowa | Charron J.,UniversiteLaval | Ko C.,University of Kentucky | Ascoli M.,University of Iowa
Molecular Endocrinology | Year: 2011

MAPK kinase (MEK)1 and MEK2 were deleted from Leydig cells by crossing Mek1f/f;Mek2-/- and Cyp17iCre mice. Primary cultures of Leydig cell from mice of the appropriate genotype (Mek1f/f; Mek2-/-;iCre+) show decreased, but still detectable, MEK1 expression and decreased or absent ERK1/2 phosphorylation when stimulated with epidermal growth factor, Kit ligand, cAMP, or human choriogonadotropin (hCG). The body or testicular weights of Mek1f/f;Mek2-/-;iCre+ mice are not significantly affected, but the testis have fewer Leydig cells. The Leydig cell hypoplasia is paralleled by decreased testicular expression of several Leydig cell markers, such as the lutropin receptor, steroidogenic acute regulatory protein, cholesterol side chain cleavage enzyme, 17α- hydroxylase, and estrogen sulfotransferase. The expression of Sertoli or germ cell markers, as well as the shape, size, and cellular composition of the seminiferous tubules, are not affected. cAMP accumulation in response to hCG stimulation in primary cultures of Leydig cells from Mek1f/f; Mek2-/-;iCre+ mice is normal, but basal testosterone and testosterone syntheses provoked by addition of hCG or a cAMP analog, or by addition of substrates such as 22-hydroxycholesterol or pregnenolone, are barely detectable. The Mek1f/f;Mek2-/-;iCre+ males show decreased intratesticular testosterone and display several signs of hypoandrogenemia, such as elevated serum LH, decreased expression of two renal androgen-responsive genes, and decreased seminal vesicle weight. Also, in spite of normal sperm number and motility, the Mek1f/f;Mek2-/-;iCre+ mice show reduced fertility. These studies show that deletion of MEK1/2 in Leydig cells results in Leydig cell hypoplasia, hypoandrogenemia, and reduced fertility. © 2011 by The Endocrine Society. Source


Drainville A.C.,UniversiteLaval
Globalizations | Year: 2011

Inquiries into global discipline and dissent are apt to carry thinking from the most situated and specific instances of power and counter-power to broad structural orders, in a manner that is remarkably independent of political mediation and thus respectful of the ways in which actually existing human beings negotiate lives sutured at the intersection of the local and the global. This article is part of a broader theoretical project that is informed by historical research on a wide variety of movements of resistance against world ordering-from slave revolts at the beginning of the nineteenth century, to coolies uprisings in the twentieth, to gas and water wars at the beginning of the twenty-first. In it, I come to distinguish between two modes of relation to the world economy. In creative dislocation, situated life gets resolved before being carried off, neat and bereft of possibilities, into the global. In the process, a putative subject gets made that carries a reified sense of itself. In the dialectics of presence, the unresolved lot of situated life gets taken whole to the world economy. Wars of position give way to wars of movement. Dialectically, positions come to be charged with a sense of context and possibilities. World-historical subjects sometimes make themselves for a while, from conditions that were not of their choosing. © 2011 Copyright Taylor and Francis Group, LLC. Source


Bier N.,Laval University | Bier N.,Universite de Sherbrooke | Macoir J.,Laval University | Macoir J.,UniversiteLaval
Journal of Clinical and Experimental Neuropsychology | Year: 2010

The purpose of this article is to present current evidence regarding the role of semantic memory in everyday actions. First we describe key models of everyday actions. We then discuss current evidence regarding the role of semantic memory in everyday actions. We reviewed articles reporting on the execution and representation of everyday actions in populations with semantic-memory deficits and single-object use in patients with semantic dementia. Although the evidence is sparse, the general conclusion of this review is that semantic memory seems necessary to support everyday actions. Finally, future challenges and research perspectives are discussed. © 2009 Psychology Press. Source


Aryanpour G.,UniversiteLaval | Mashl S.,Michigan Technological University | Warke V.,Bodycote Hot Isostatic Pressing Inc.
Powder Metallurgy | Year: 2013

A constitutive model is proposed for the densification of metal powder during hot isostatic pressing. The model considers an inelastic deformation resulting from time dependent (viscoplastic) and time independent (plastic) mechanisms during loading. With employing the Abouaf's formalism for viscoplastic part, the paper is focused mainly on the plasticity contribution including the hardening effects of both relative density and the equivalent plastic strain. The proposed plastic-viscoplastic model is summarised to an equation expressing the densification rate under hydrostatic loading. The gas atomised 316LN stainless steel powder was used in this study. Model parameters necessary for simulation of HIP process during a given pressure ramp at constant temperature are identified using previously published data. The identified model is then verified using experimental data obtained from HIP trials performed at another fixed temperature but with varied pressure ramp rates. A good agreement was found between the model prediction and the experimental results. © 2013 Institute of Materials, Minerals and Mining. Source


Bilcke J.,University of Antwerp | Beutels P.,University of Antwerp | Brisson M.,UniversiteLaval | Brisson M.,University of Quebec | Jit M.,Public Health England
Medical Decision Making | Year: 2011

Accounting for uncertainty is now a standard part of decision-analytic modeling and is recommended by many health technology agencies and published guidelines. However, the scope of such analyses is often limited, even though techniques have been developed for presenting the effects of methodological, structural, and parameter uncertainty on model results. To help bring these techniques into mainstream use, the authors present a step-by-step guide that offers an integrated approach to account for different kinds of uncertainty in the same model, along with a checklist for assessing the way in which uncertainty has been incorporated. The guide also addresses special situations such as when a source of uncertainty is difficult to parameterize, resources are limited for an ideal exploration of uncertainty, or evidence to inform the model is not available or not reliable. Methods for identifying the sources of uncertainty that influence results most are also described. Besides guiding analysts, the guide and checklist may be useful to decision makers who need to assess how well uncertainty has been accounted for in a decision-analytic model before using the results to make a decision. Source

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