Skunk River Review 2012-2013, Vol 25

https://openspace.dmacc.edu/skunkriver/1021/thumbnail.jp

Why Don't CD8+ T Cells Reduce the Lifespan of SIV-Infected Cells In Vivo?

In January 2010 two groups independently published the observation that the depletion of CD8+ cells in SIV-infected macaques had no detectable impact on the lifespan of productively infected cells. This unexpected observation led the authors to suggest that CD8+ T cells control SIV viraemia via non-lytic mechanisms. However, a number of alternative plausible explanations, compatible with a lytic model of CD8+ T cell control, were proposed. This left the field with no consensus on how to interpret these experiments and no clear indication whether CD8+ T cells operated primarily via a lytic or a non-lytic mechanism. The aim of this work was to investigate why CD8+ T cells do not appear to reduce the lifespan of SIV-infected cells in vivo

Can Non-lytic CD8+T Cells Drive HIV-1 Escape?

The CD8+ T cell effector mechanisms that mediate control of HIV-1 and SIV infections remain poorly understood. Recent work suggests that the mechanism may be primarily non-lytic. This is in apparent conflict with the observation that SIV and HIV-1 variants that escape CD8+ T cell surveillance are frequently selected. Whilst it is clear that a variant that has escaped a lytic response can have a fitness advantage compared to the wild-type, it is less obvious that this holds in the face of non-lytic control where both wild-type and variant infected cells would be affected by soluble factors. In particular, the high motility of T cells in lymphoid tissue would be expected to rapidly destroy local effects making selection of escape variants by non-lytic responses unlikely. The observation of frequent HIV-1 and SIV escape poses a number of questions. Most importantly, is the consistent observation of viral escape proof that HIV-1- and SIV-specific CD8+ T cells lyse infected cells or can this also be the result of non-lytic control? Additionally, the rate at which a variant strain escapes a lytic CD8+ T cell response is related to the strength of the response. Is the same relationship true for a non-lytic response? Finally, the potential anti-viral control mediated by non-lytic mechanisms compared to lytic mechanisms is unknown. These questions cannot be addressed with current experimental techniques nor with the standard mathematical models. Instead we have developed a 3D cellular automaton model of HIV-1 which captures spatial and temporal dynamics. The model reproduces in vivo HIV-1 dynamics at the cellular and population level. Using this model we demonstrate that non-lytic effector mechanisms can select for escape variants but that outgrowth of the variant is slower and less frequent than from a lytic response so that non-lytic responses can potentially offer more durable control

21-6-25, [stade de] Colombes, championnat de Paris, passage du 1500 [mètres, Bontemps (15) en tête, Baraton (49)] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 102007Appartient à l’ensemble documentaire : Pho20RolImage de press

Positive views of aging reduce risk of developing later-life obesity

The obesity epidemic among older adults is expected to continue increasing unless public-health efforts address this age group. Yet, little is known about psychosocial determinants of obesity that relate specifically to older persons. In this study, we investigated for the first time whether self-perceptions of aging (SPA), defined as beliefs about oneself as an older person that are assimilated from society, relate to new cases of obesity. This seemed plausible because older persons who report more-positive SPA tend to engage in more health-promoting behaviors. Our sample consisted of 5702 Americans in the nationally representative Health and Retirement Study who were aged 60 years or older and not obese at baseline. The participants were followed from 2008 to 2014. As predicted, older persons with more-positive SPA, compared to those with more-negative SPA, were significantly less likely to become obese over the next 6 years, after adjusting for relevant covariates. For example, according to our model, a participant with the most-positive SPA score was 27% less likely to become obese than a same-aged peer with an average score on the SPA measure. These findings suggest that interventions aimed at reducing the prevalence of obesity in later life could benefit from targeting SPA. Keywords: Ageism, Stereotyping, Healthy aging, Obesity, Self perceptions of aging, Views of aging, Behaviors, Preventive healt

Factor loadings, communalities, means, and standard deviations for the Pettiness Scale in Study 1 (N = 1720).

<p>Factor loadings, communalities, means, and standard deviations for the Pettiness Scale in Study 1 (N = 1720).</p

Healthcare Quality and Dementia Risk

Low healthcare quality has been found to predict the development of several illnesses in older adults, while the evidence on dementia is still lacking. This study assesses whether and to what extent experiencing low healthcare quality can be associated with developing dementia in people 60-years-old and greater. Participants in the Health and Retirement Study (HRS), without dementia and 60-years-old and greater at baseline, were followed 2006 through 2019. Experiencing low healthcare quality was assessed at baseline through healthcare discrimination and dissatisfaction with healthcare services. The outcome, development of new cases of dementia, was determined through physician diagnosis or a cognition score compatible with dementia (assessed by the Telephone Interview for Cognitive Status). Cox regression is used to estimate the hazard ratio (HR) of dementia, adjusting for participants' demographic, health, and socioeconomic factors. Experiencing low healthcare quality is associated with increased dementia risk over 12 years (unadjusted HR: 1.68, 95% CI: 1.27 - 2.21, p-value< 0.001; fully adjusted HR: 1.50, 95% CI: 1.12 - 2.01, p- value: 0.006). Healthcare discrimination and dissatisfaction with the healthcare quality received are independently associated with increased dementia risk. To date, most measures to reduce dementia have focused on individual-level behaviors. Our findings suggest that implementing structural changes to improve healthcare quality delivery for older persons may reduce dementia prevalence

Healthcare Quality and Dementia Risk

Low healthcare quality has been found to predict the development of several illnesses in older adults, while the evidence on dementia is still lacking. This study assesses whether and to what extent experiencing low healthcare quality can be associated with developing dementia in people 60-years-old and greater. Participants in the Health and Retirement Study (HRS), without dementia and 60-years-old and greater at baseline, were followed 2006 through 2019. Experiencing low healthcare quality was assessed at baseline through healthcare discrimination and dissatisfaction with healthcare services. The outcome, development of new cases of dementia, was determined through physician diagnosis or a cognition score compatible with dementia (assessed by the Telephone Interview for Cognitive Status). Cox regression is used to estimate the hazard ratio (HR) of dementia, adjusting for participants' demographic, health, and socioeconomic factors. Experiencing low healthcare quality is associated with increased dementia risk over 12 years (unadjusted HR: 1.68, 95%CI: 1.27 - 2.21, p-value< 0.001; fully adjusted HR: 1.50, 95%CI: 1.12 - 2.01, p-value: 0.006). Healthcare discrimination and dissatisfaction with the healthcare quality received are independently associated with increased dementia risk. To date, most measures to reduce dementia have focused on individual-level behaviors. Our findings suggest that implementing structural changes to improve healthcare quality delivery for older persons may reduce dementia prevalence