The effect of high-altitude on human skeletal muscle energetics: 31P-MRS results from the caudwell xtreme everest expedition

Many disease states are associated with regional or systemic hypoxia. The study of healthy individuals exposed to high-altitude hypoxia offers a way to explore hypoxic adaptation without the confounding effects of disease and therapeutic interventions. Using 31P magnetic resonance spectroscopy and imaging, we investigated skeletal muscle energetics and morphology after exposure to hypobaric hypoxia in seven altitude-naïve subjects (trekkers) and seven experienced climbers. The trekkers ascended to 5300 m while the climbers ascended above 7950 m. Before the study, climbers had better mitochondrial function (evidenced by shorter phosphocreatine recovery halftime) than trekkers: 16±1 vs. 22±2 s (mean ± SE, p<0.01). Climbers had higher resting [Pi] than trekkers before the expedition and resting [Pi] was raised across both groups on their return (PRE: 2.6±0.2 vs. POST: 3.0±0.2 mM, p<0.05). There was significant muscle atrophy post-CXE (PRE: 4.7±0.2 vs. POST: 4.5±0.2 cm2, p<0.05), yet exercising metabolites were unchanged. These results suggest that, in response to high altitude hypoxia, skeletal muscle function is maintained in humans, despite significant atrophy

OBSERVATION OF THE D, E AND delta MESONS IN pi- p INTERACTIONS AT 12-GeV/c AND 15-GeV/c

The authors have observed the D(1285), E(1420) and delta (975) mesons produced in 12 and 15 GeV/c pi /sup -/p interactions at the CERN Omega Spectrometer. Production cross sections and decay branching ratios are presented. Analysis of the decay D(1285) to delta (975) pi favours a spin parity assignment of 1/sup +/. (24 refs)

AN AMPLITUDE ANALYSIS OF pi pi SCATTERING FROM NEW DATA ON THE REACTION pi- p ---> pi+ pi- n

We have carried out a partial-wave analysis of ππ scattering in the mass range 1.0 to 2.08 GeV/c2. We find solutions similar to those obtained in previous analyses below 1.8 GeV/c2 but, in addition, we obtain a new solution which does not suffer from violations of unitarity and is compatible with data from other channels. This solution, when continued to 2.08 GeV/c2, shows a g meson with mass and width of 1.734± 0.010 GeV/c2and 0.322±0.035 GeV/c2 respectively, and an h meson with mass 1.935±0.013 GeV/c2and width 0.263±0.057 GeV/c2. The L = 2 partial wave contains the f meson and an additional resonance with parameters m = 1.502±0.025 Gev/c2, Γ = 0.165±0.042 GeV/c2and x = 0.19±0.03. If we associate this state with the f′(1514), our ππ branching fraction is considerably higher than previous determinations. An SU(3) fit to the 2+ nonet yields a mixing angle of 38.4± 1.3°. © 1979

PRODUCTION OF A20 AND omega-prime (1675) IN THE REACTION pi- p ---> pi+ pi- pi0 n AT 12-GeV/c AND 15-GeV/c

Data on the reaction pi /sup -/p to pi /sup +/ pi /sup -/ pi /sup 0/n have been taken at 12 and 15 GeV/c with the CERN Omega multiparticle spectrometer. In a 3-pion partial-wave analysis strong production of A /sub 2//sup 0/ (1310) and omega * (1675) is observed. Total and differential cross sections are determined and density matrix elements presented as a function of t in the t- and s-channel frames. The energy dependence of A/sub 2//sup 0/ production is studied, and a comparison of omega (780), A/sub 2//sup 0/ (1310) and omega * (1675) production is made. (15 refs)

F0 (1270) PRODUCTION IN THE REACTION PI- P ---> PI+ PI- N AT 12-GEV/C AND 15-GEV/C

The production of the f0 (1270) has been studied in the reaction π-p → π+π-n at 12 and 15 GeV/c in the momentum transfer range 0.02 to 0.80 GeV2. Differential and total cross sections for the reaction π-p → f0n have been determined. The f0 decay density matrix elements have been evaluated requiring all the matrix eigenvalues to be non-negative. The relative unnatural and natural parity exchange contributions to the f0 production have been studied. The results are compared with a Regge exchange model formulated in terms of the pion and A2 exchanges including cut contributions. © 1977