Body composition and maximum alactic anaerobic performance during a one month stay at high altitude

Prolonged altitude exposure usually leads to considerable weight loss of which a large part is from muscle tissue. This loss reduces maximum alactic anaerobic muscle power. It was hypothesized that most of the weight loss may simply be the result of malnutrition due to lack of palatable food in an uncomfortable environment. To test this hypothesis eight healthy male subjects (age 33.7 \ub1 4.6 S.C. yr), well acclimatized to prevent symptoms of acute mountain sickness, were exposed for 4 weeks to an altitude of 5050 m with access to a large choice of palatable food in comfortable conditions. Body weight (with a scale), body composition (from skinfolds), arm muscle plus bone cross-sectional area (Am + b) and muscle plus bone leg volume (Vm + b) (from skinfolds and circumferences), maximum voluntary contraction force of the elbow flexors (MVC, with a load cell) and maximum jumping height (Hmax, on a platform) were measured before departure (SL) and in the first (ALT1), second (ALT2) and fourth week (ALT4) of their altitude sojourn. Three-day dietary records were obtained at SL and at ALT4. Body mass had decreased significantly at ALT2 (-3.8%) and at ALT4 (-4.6%) likely reflecting changes in body water homeostasis. No changes were found in \ufat, Am + b, Vm + b, MVC or Hmax. Average dietary intake at SL was 8.96 \ub1 1.45 MJ and had increased to 13.59 \ub1 3.07 MJ at ALT4. In conclusion, up to an altitude of 5050 m loss of body mass from fat and muscle tissue, and hence impairment of maximum anaerobic muscle power (alactic) appears to be avoidable by food intake matched to energy expenditure. The latter may be achieved simply by proper acclimatization, sufficient comfort and availability of palatable food

Single cytokine CD4 and CD8 T-cell responses to polyclonal stimulation with SEB.

<p>The magnitude of CD4 (A) and CD8 (B) T-cell IFN-γ, IL-2, TNF-α or any cytokine (Any) responses following short-term stimulation with SEB in HIV-unexposed (HU) and HIV- exposed uninfected (HEU) infants in month 3 (M3) and month 12 (M12) age groups. The black line is the median frequency of T-cells expressing the indicated cytokine or any cytokine. The Mann Whitney U test was used to assess differences between the two groups.</p

Single cytokine CD4 and CD8 T-cell responses to vaccine antigens.

<p>The magnitude of CD4 (A) and CD8 (B) T-cell IFN-γ, IL-2, TNF-α or any cytokine (Any) responses following short term stimulation with PPD in HIV-unexposed (HU) and HIV-exposed uninfected (HEU) infants in month 3 (M3) and month 12 (M12) age groups. Similarly, the magnitude of cytokine responses to TT are shown in (C) for CD4 T-cells only. The horizontal black line is the median frequency of T-cells expressing the indicated cytokine or any cytokine. The Mann Whitney U test was used to assess differences between the two groups.</p

Memory phenotype of vaccine antigen responsive CD4 T-cells.

<p>(A) Analysis of the memory phenotype of CD4 T-cells that express any cytokine (IFN-γ, IL-2 or TNF-α) in response to short-term stimulation with PPD. (B) A similar analysis was carried out following short-term stimulation with TT. Comparisons were made between HIV-unexposed (HU) and HIV-exposed uninfected (HEU) infants at month 3 (M3) and month 12 (M12) age groups. The horizontal line in the box and whisker plots is the median percentage of cytokine secreting T-cells with a particular surface memory phenotype, the box is the interquartile range and the whiskers the 10^th and 90^th percentiles. T_CM: central memory, T_EM: effector memory, T_EMRA: effector memory that re-express CD45RA. The Mann Whitney U test was used to assess differences between the two groups.</p

Polyfunctional CD4 T-cell responses to stimulation with vaccine antigens and following polyclonal stimulation with SEB.

<p>(A) CD4 T-cells expressing combinations of IFN-γ, IL-2 and/or TNF-α were analysed using Boolean gating following short-term stimulation with PPD in HIV-unexposed (HU) and HIV-exposed uninfected (HEU) infants in the month 3 (M3) age group. (B) A similar analysis is shown assessing TT responses in the month 12 (M12) age group. Similarly, polyfunctional SEB responses in M3 (C) and M12 (D) age groups are shown. The black line is the median frequency of T cells expressing the indicated cytokine combination, the box is the interquartile range and the whiskers the 10^th and 90^th percentiles. The Mann Whitney U test was used to assess differences between the two groups.</p