4 resultados para Step-stress accelerated life testing

em DigitalCommons@The Texas Medical Center


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The causes and contexts of food insecurity among children in the U.S. are poorly understood because the prevalence of food insecurity at the child level is low compared to the prevalence of household food insecurity. In addition, caregivers may be reluctant to admit their children may not be getting enough food due to shame or fear they might lose custody of their children. Based on our ongoing qualitative research with mothers of young children, we suggest that food security among children is related to adverse childhood experiences of caregivers. This translates into poor mental and physical health in adolescence and adulthood, which can lead to inability to secure and maintain meaningful employment that pays a living wage. In this paper we propose that researchers shift the framework for understanding food insecurity in the United States to adopt a life course approach. This demands we pay greater attention to the lifelong consequences of exposure to trauma or toxic stress—exposure to violence, rape, abuse and neglect, and housing, food, and other forms of deprivation—during childhood. We then describe three case studies of women from our ongoing study to describe a variety of toxic stress exposures and how they have an impact on a woman’s earning potential, her mental health, and attitudes toward raising children. Each woman describes her exposure to violence and deprivation as a child and adolescent, describes experiences with child hunger, and explains how her experiences have shaped her ability to nourish her children. We describe ways in which we can shift the nature of research investigations on food insecurity, and provide recommendations for policy-oriented solutions regarding income support programs, early intervention programs, child and adult mental health services, and violence prevention programs.

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Objective. The purpose of this study was to examine the association of perceived stress and passing the fitness test in a cohort of Department of Defense active duty members. Reports of this association have been suggested in numerous articles. Methods. The 2005 DoD Survey of Health Related Behaviors Among Active Duty Military Personnel was used to examine the association between the participants’ perceived levels of stress from family and/or work related sources and the respondents’ last required fitness test taking into account potential confounder of the association. Measures of association were obtained from logistic regression models. Results. Participants who experienced “some” or “a lot” of stress either from work sources (OR 0.69, 95% CI: 0.58-0.87) or from personal/family sources (OR 0.70, 95% CI: 0.57-0.86) were less likely to pass the fitness test when compared to their counterparts who experienced “none” or “a little” stress. Additionally, those who reported “some” or “a lot” of stress either from work sources (OR 0.54, 95% CI: 0.41-0.70) or from personal/family sources (OR 0.54, 95% CI: 0.44-0.67) that interfered with their military duties were also less likely to pass the fitness test. The multivariate adjustment only slightly reduced the unadjusted association. Conclusions . An association exists between perceived stress levels and outcome of fitness testing. The higher the level of stress perceived, the less likely the person will be to pass the fitness test. Stress-related intervention might be useful to help the military members to achieve the level of fitness needed to perform their duties.^

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Viral invasion of the central nervous system (CNS) and development of neurological symptoms is a characteristic of many retroviruses. The mechanism by which retrovirus infection causes neurological dysfunction has yet to be fully elucidated. Given the complexity of the retrovirus-mediated neuropathogenesis, studies using small animal models are extremely valuable. Our laboratory has used a mutant moloney murine leukemia retrovirus, ts1-mediated neurodegneration. We hypothesize that astrocytes play an important role in ts1-induced neurodegeneration since they are retroviral reservoirs and supporting cells for neurons. It has been shown that ts1 is able to infect astrocytes in vivo and in vitro. Astrocytes, the dominant cell population in the CNS, extend their end feet to endothelial cells and neuronal synapse to provide neuronal support. Signs of oxidative stress in the ts1-infected CNS have been well-documented from previous studies. After viral infection, retroviral DNA is generated from its RNA genome and integrated into the host genome. In this study, we identified the life cycle of ts1 in the infected astrocytes. During the infection, we observed reactive oxygen species (ROS) upregulations: one at low levels during the early infection phase and another at high levels during the late infection phase. Initially we hypothesized that p53 might play an important role in ts1-mediated astrocytic cell death. Subsequently, we found that p53 is unlikely to be involved in the ts1-mediated astrocytic cell death. Instead, p53 phosphorylation was increased by the early ROS upregulation via ATM, the protein encoded by the ataxia-telangiectasia (A-T) mutated gene. The early upregulation of p53 delayed viral gene expression by suppressing expression of the catalytic subunit of NADPH oxidase (NOX). We further demonstrated that the ROS upregulation induced by NOX activation plays an important role in establishing retroviral genome into the host. Inhibition of NOX decreased viral replication and delayed the onset of pathological symptoms in ts1-infected mice. These observations lead us to conclude that suppression of NOX not only prevents the establishment of the retrovirus but also decreases oxidative stress in the CNS. This study provides us with new perspectives on the retrovirus-host cell interaction and sheds light on retrovirus-induced neurodegeneration as a result of the astrocyte-neuron interaction.