The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Donald M Mock - One of the best experts on this subject based on the ideXlab platform.
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red blood cell life span in the ovine fetus
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2000Co-Authors: Robert A Brace, Christiane Langendorfer, Taebok Song, Donald M MockAbstract:Red cell life span within the fetal circulation has not been reported, although erythrocyte life span has been studied in the adult and newborn. The present study quantified red cell life span in 1...
William R Sterner - One of the best experts on this subject based on the ideXlab platform.
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Integrating Existentialism and Super's Life‐Span, Life‐Space Approach
The Career Development Quarterly, 2012Co-Authors: William R SternerAbstract:As workers face a changing and ever-complex employment landscape, traditional career theories and approaches may not be sufficient in meeting career challenges. Calls for integrated career theories have emerged as more people seek meaning and purpose in their lives and careers. This article proposes a career counseling option that integrates existentialism and Super's (1990) Life-Span, life-space approach to establish a foundation for a broader approach to career development that views clients holistically by exploring life and career meaning and purpose from a developmental perspective. A case example and interventions are provided to demonstrate practical application and a contextual framework, along with implications for counselors. Keywords: existentialism. Super's approach, career, career development Existential therapy evolved to address angst often associated with living in a postagrarian society. As the workforce became increasingly industrialized, a sense of isolation, alienation, and meaninglcssness emerged as part of the human condition (Corey, 2009). Existentialism describes a yearning for deeper understanding of the human condition and searching for significance, meaning, and purpose of one's life. May (1961) indicated that existential therapy focuses on the existing person as he or she is emerging or becoming. The central question asked from an existential perspective is, "What is the source of meaning for me in life?" According to Yalom ( 1 980), existentialism is difficult to define and often subjective in its meaning. In his view, because of the subjectivity associated with defining this construct, existential themes (e.g., freedom, meaning, and death) create common ground. Yalom explained that existential therapy is not derived from a specific theory but rather is a psychotherapeutic approach with well-established roots in existential philosophy. Existentialism has gained momentum in the counseling literature (e.g., Chen, 2001; Cohen, 2003; Maglio, Buttcrfield, & Borgen, 2005) as counselors seek treatment that aligns with client values, beliefs, and life meaning and purpose. Existential therapy has been used in counseling to address various problems such as life adjustment concerns, acute and chronic illnesses, grief and loss, cross-cultural issues, and end-of-life realities. One area in which existential therapy may have important applications is in career counseling. Given the changing employment landscape, integrating existentialism into traditional career counseling models can provide a comprehensive approach to addressing complex employment issues. Unfortunately, existential therapy has not fully manifested in career counseling despite its practical approaches and specific application in career decision making across the life span (Cohen, 2003). Several scholars (Krumboltz, 1998; Mitchell, Levin, & Krumboltz, 1999; Savickas, 2000) have advocated establishing new career counseling models that reflect the postmodern workforce in which workers place less emphasis on career opportunities that align with specific traits and instead seek meaning, purpose, and value in the career development process (Thorngren & Feit, 2001). Integrating existential therapy with Super's (1990) Life-Span, life-space approach may have potential applications given that meaning and values associated with career development continually evolve across the life span. This article introduces an approach that integrates existential therapy and Super's developmental approach. Existentialism and Career Counseling: Staring the Problem Historically, traditional career counseling focused on matching clients' work values, skills, abilities, and interests with occupational opportunities. Job placement or career clarification was often the end goal. Guindon and Harina (2002) indicated that even though there is movement toward an integrative and holistic view in counseling, many career counselors continue to draw from traditional career counseling theories. …
Benjamin T. Kile - One of the best experts on this subject based on the ideXlab platform.
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The Regulation of Platelet Life Span
Platelets, 2013Co-Authors: Emma C. Josefsson, Mark R. Dowling, Marion Lebois, Benjamin T. KileAbstract:The human body produces approximately 100 billion platelets per day. At steady state, only a small fraction of these are consumed in hemostatic processes. The majority are cleared by the reticuloendothelial system in the liver and spleen. Their time in the circulation is relatively brief; up to 10 days in humans and 5 days in mice. In recent years it has become apparent that platelets contain an apoptotic program that regulates their survival. Genetic or pharmacological manipulation of the program can reduce or extend platelet life span in vivo . This chapter reviews the history of platelet life span research, highlights recent developments, and outlines some emerging themes in the field.
Stephen L Helfand - One of the best experts on this subject based on the ideXlab platform.
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sir2 mediates longevity in the fly through a pathway related to calorie restriction
Proceedings of the National Academy of Sciences of the United States of America, 2004Co-Authors: Blanka Rogina, Stephen L HelfandAbstract:Calorie restriction can extend life span in a variety of species including mammals, flies, nematodes, and yeast. Despite the importance of this nearly universal effect, little is understood about the molecular mechanisms that mediate the Life-Span-extending effect of calorie restriction in metazoans. Sir2 is known to be involved in life span determination and calorie restriction in yeast mother cells. In nematodes increased Sir2 can extend life span, but a direct link to calorie restriction has not been demonstrated. We now report that Sir2 is directly involved in the calorie-restriction Life-Span-extending pathway in Drosophila. We demonstrate that an increase in Drosophila Sir2 (dSir2) extends life span, whereas a decrease in dSir2 blocks the Life-Span-extending effect of calorie reduction or rpd3 mutations. These data lead us to propose a genetic pathway by which calorie restriction extends life span and provides a framework for genetic and pharmacological studies of life span extension in metazoans.
Trudy F. C. Mackay - One of the best experts on this subject based on the ideXlab platform.
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Context-dependent genetic architecture of Drosophila life span
PLoS biology, 2020Co-Authors: Wen Huang, Terry Campbell, Mary Anna Carbone, W. Elizabeth Jones, Desiree Unselt, Robert R. H. Anholt, Trudy F. C. MackayAbstract:Understanding the genetic basis of variation in life span is a major challenge that is difficult to address in human populations. Evolutionary theory predicts that alleles affecting natural variation in life span will have properties that enable them to persist in populations at intermediate frequencies, such as late-life–specific deleterious effects, antagonistic pleiotropic effects on early and late-age fitness components, and/or sex- and environment-specific or antagonistic effects. Here, we quantified variation in life span in males and females reared in 3 thermal environments for the sequenced, inbred lines of the Drosophila melanogaster Genetic Reference Panel (DGRP) and an advanced intercross outbred population derived from a subset of DGRP lines. Quantitative genetic analyses of life span and the micro-environmental variance of life span in the DGRP revealed significant genetic variance for both traits within each sex and environment, as well as significant genotype-by-sex interaction (GSI) and genotype-by-environment interaction (GEI). Genome-wide association (GWA) mapping in both populations implicates over 2,000 candidate genes with sex- and environment-specific or antagonistic pleiotropic allelic effects. Over 1,000 of these genes are associated with variation in life span in other D. melanogaster populations. We functionally assessed the effects of 15 candidate genes using RNA interference (RNAi): all affected life span and/or micro-environmental variance of life span in at least one sex and environment and exhibited sex-and environment-specific effects. Our results implicate novel candidate genes affecting life span and suggest that variation for life span may be maintained by variable allelic effects in heterogeneous environments.
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The Complex Genetic Architecture of Drosophila Life Span
Experimental aging research, 2002Co-Authors: Jeff Leips, Trudy F. C. MackayAbstract:Continuous phenotypic variation in life span results from segregating genetic variation at multiple loci, the environmental sensitivity of expression of these loci, and the history of environmental variation experienced by the organism throughout its life. We have mapped quantitative trait loci (QTL) that produce variation in the life span of mated Drosophila melanogaster using a panel of recombinant inbred lines (RIL) that were backcrossed to the parental strains from which they were derived. Five QTL were identified that influence mated life span, three were male-specific, one was female-specific, and one affected life span in both sexes. The additive allelic effects and dominance of QTL were highly sex-specific. One pair of QTL also exhibited significant epistatic effects on life span. We summarize all of the QTL mapping data for Drosophila life span, and outline future prospects for disentangling the genetic and environmental influences on this trait.
