The Effects of Twelve Weeks of Combined Resistance and Aerobic Training on Arm Lean Mass in Post-Menopausal, Obese Women

ABSTRACT Sarcopenia, a loss in muscle mass as a result of aging, is an independent risk factor for disability and is significantly associated with self-reported physical disability in both men and women. Strength training reverses the loss of, or maintains muscle mass in individuals as they age. PURPOSE: To examine the potential change in lean muscle mass of the arms in response to a 12-week combination strength and aerobic exercise training intervention in post-menopausal (55-75 years), obese women. METHODS: Forty-one women were randomly assigned to either an exercise (EX, n=22 ) or education (ED, n=19) group. For twelve weeks (12 WT), the EX group participated in resistance and aerobic training three days per week. Participants performed 2 sets of the following 8 resistance exercises at 8-12 RM: “lat” pulldown, chest press, seated row, leg press, leg extension, leg curl, hip adduction, and hip abduction. The first set consisted of 8 repetitions, while the second set was to failure. The participants then walked on a treadmill at 75 - 85% heart rate reserve for 30 min. The ED group participated in education sessions twice per week and were restricted from exercise. Lean muscle mass of the arms was measured before (BT) and after (AT) 12 WT via dual-energy X-ray absorptiometry (DEXA). Strength was measured using eight repetition maximum (8RM) on chest press BT and AT. VO2max was estimated using a treadmill exercise bout where participants exercised to 85% of their heart rate reserve (BT & AT). RESULTS: There was a group x training interaction for left arm lean mass (EX BT: 2.24 ± 0.086, EX AT: 2.38 ± 0.092; ED BT: 2.11 ± 0.092, ED AT: 2.12 ± 0.100 kg, p=0.018) and total arm lean mass (EX BT: 4.54 ± 0.164, EX AT: 4.76 ± 0.177; ED BT: 4.379 ± 0.177, ED AT: 4.30 ± 0.191 kg, p=0.048). We observed a group x training interaction for VO2 max (EX BT: 21.1 ± 0.82, EX AT: 23.8 ± 0.80; ED BT: 19.9 ± 0.88, ED AT: 20.1 ± 0.86 ml·kg-1·min-1 p=0.006) and chest press 8RM (EX BT: 28.1 ± 1.16, EX AT: 38.9 ± 1.53; ED BT: 25.10 ± 1.4, ED AT: 23.9 ± 0.1.9 kg, pCONCLUSION: An increase in lean mass of the arms, strength, and aerobic fitness can be associated with a decrease in disability. The results of this study provide further evidence that strength training can be used as an intervention to combat age related sarcopenia. Furthermore, the training intervention utilized in this study can serve a population who does not normally meet the physical activity guidelines outlined by the American College of Sports Medicine in order to increase arm lean mass, VO2 max, and strength

Target cell availability, rather than breast milk factors, dictates mother-to-infant transmission of SIV in sooty mangabeys and rhesus macaques.

Mother-to-infant transmission (MTIT) of HIV is a serious global health concern, with over 300,000 children newly infected in 2011. SIV infection of rhesus macaques (RMs) results in similar rates of MTIT to that of HIV in humans. In contrast, SIV infection of sooty mangabeys (SMs) rarely results in MTIT. The mechanisms underlying protection from MTIT in SMs are unknown. In this study we tested the hypotheses that breast milk factors and/or target cell availability dictate the rate of MTIT in RMs (transmitters) and SMs (non-transmitters). We measured viral loads (cell-free and cell-associated), levels of immune mediators, and the ability to inhibit SIV infection in vitro in milk obtained from lactating RMs and SMs. In addition, we assessed the levels of target cells (CD4+CCR5+ T cells) in gastrointestinal and lymphoid tissues, including those relevant to breastfeeding transmission, as well as peripheral blood from uninfected RM and SM infants. We found that frequently-transmitting RMs did not have higher levels of cell-free or cell-associated viral loads in milk compared to rarely-transmitting SMs. Milk from both RMs and SMs moderately inhibited in vitro SIV infection, and presence of the examined immune mediators in these two species did not readily explain the differential rates of transmission. Importantly, we found that the percentage of CD4+CCR5+ T cells was significantly lower in all tissues in infant SMs as compared to infant RMs despite robust levels of CD4+ T cell proliferation in both species. The difference between the frequently-transmitting RMs and rarely-transmitting SMs was most pronounced in CD4+ memory T cells in the spleen, jejunum, and colon as well as in central and effector memory CD4+ T cells in the peripheral blood. We propose that limited availability of SIV target cells in infant SMs represents a key evolutionary adaptation to reduce the risk of MTIT in SIV-infected SMs

IL-7 is a potent and proviral strain–specific inducer of latent HIV-1 cellular reservoirs of infected individuals on virally suppressive HAART

The persistence of HIV-1 in virally suppressed infected individuals on highly active antiretroviral therapy (HAART) remains a major therapeutic problem. The use of cytokines has been envisioned as an additional therapeutic strategy to stimulate latent proviruses in these individuals. Immune activation therapy using IL-2 has shown some promise. In the present study, we found that IL-7 was significantly more effective at enhancing HIV-1 proviral reactivation than either IL-2 alone or IL-2 combined with phytohemagglutinin (PHA) in CD8-depleted PBMCs. IL-7 also showed a positive trend for inducing proviral reactivation from resting CD4(+) T lymphocytes from HIV-1–infected patients on suppressive HAART. Moreover, the phylogenetic analyses of viral envelope gp120 genes from induced viruses indicated that distinct proviral quasispecies had been activated by IL-7, as compared with those activated by the PHA/IL-2 treatment. These studies thus demonstrate that different activators of proviral latency may perturb and potentially deplete only selected, specific portions of the proviral archive in virally suppressed individuals. The known immunomodulatory effects of IL-7 could be combined with its ability to stimulate HIV-1 replication from resting CD4(+) T lymphocytes, in addition to other moieties, to potentially deplete HIV-1 reservoirs and lead to the rational design of immune-antiretroviral approaches

Clinical features of nonhuman primate infants.

<p>Clinical features of nonhuman primate infants.</p

Similar cell-free and cell-associated SIV levels in blood and milk from RMs and SMs following pharmacologic induction of lactation.

<p>Lactation was induced using intramuscular injections of estradiol and medroxyprogesterone along with oral haloperidol followed by oxytocin injections to stimulate the milk ejection reflex. Over the 20 weeks of this study, plasma viral loads were measured via SIV RNA real time RT-PCR every 2 weeks (A). Breast milk was collected from RMs and SMs and cell-free SIV RNA was quantified in the de-fatted milk fraction by RT-PCR (B). Cell-associated SIV DNA was then measured in both PBMCs (C) and breast milk cells (D) with simultaneous albumin detection to determine cell number per reaction. Dashed lines represented the lower limit of detection for the assay. Undetectable values were plotted as half the lower limit of detection. Area under the curve analyses followed by nonparametric Mann-Whitney test was used to assess significance.</p

Memory and effector CD4+ and CD8+ T cell subsets in SM milk.

<p>The cellular fraction of breast milk was stained with monoclonal antibodies to identify the relative proportions of T cell subsets. Gating strategy was as follows: CD45 vs CD3 to identify hematopoietic T cells, then CD20 vs CD14 to exclude B cells and monocytes/macrophages, respectively, then CD4 vs CD8. The CD4+ and CD8+ populations were stained with CD28 and CD95 to identify naïve (CD28+CD95−) and memory (CD28+/−CD95+) subsets. The memory population was further differentiated into effector (CCR7−) and central (CCR7+) memory subsets.</p

T cell differentiation and proliferation in infant SM and RM tissues.

<p>(A) The proportion of naïve (CD28+CD95−) and memory (CD28+/−CD95+) CD4+ T cells in lymphoid and gastrointestinal tissues of infant SMs and RMs was measured at necropsy. For each tissue site, the total may not add to 100% because of minor populations excluded in gating. (B) The level of cell activation/proliferation was measured in CD4+ T cells isolated from multiple tissues of infant RMs and SMs using the marker Ki-67. Mann-Whitney test was used to determine significance. Comparisons without p value shown were non-significant.</p