[Cosmonauts' tolerance of the chest-back G-loads during ballistic and automatically controlled descents of space vehicles].

Analysis of cosmonauts' +Gx tolerance on the stage of ballistic or automatically controlled Soyuz descent after missions to the International space station of varying duration was performed. As compared with automatically controlled descents, tolerance of descent re-entry +G(x) following short (8-14 d) missions was marked by reliably more frequent instances of visual disorders, difficult breathing, sensation of a lump in the throat and vestibulovegetative disorders (p < 0.05). The ballistic but not controlled re-entry after long-term mission provoked visual disorders, difficulties with breathing and speech, and vestibulovegetative disorders more often (p < 0.05). A considerable HR rise due to the ballistic rather than control descent was associated with re-entry and the main parachute re-hooking for symmetrical suspension; respiration rate was the highest during parachuting. By and large, these factual data infer that the ballistic descent after various periods in spaceflight microgravity, especially after extended space missions (164-169 d), led to a dramatic loss in the body functional reserves.

[Analysis of polymorphism of bone metabolism genes and evaluation of the risk of osteopenia in cosmonauts].

Densitometry of cosmonauts following long-duration missions shows reduction of bone mineral density (BMD). On the average, post-flight BMD remains within the normal range and the broad variability of individual BMD values sometimes is qualified as local osteopenia. Individual reactions are typed by similarity of amount and rate of BMD loss. At present, analysis of functionally significant polymorphism of bone metabolism genes is the most effective instrument for diagnostics of susceptibility to osteopenia and osteoporosis. The investigation was aimed to analyze polymorphism of genes of vitamin-D and (VDR) and calcitonin (CALCR) receptors, and of collagen-1 alpha-1-chain (Col1a-1) in candidate cosmonauts and cosmonauts returned from 5 to 7-mo. missions. According to the results of analysis, in the majority of cosmonauts rapid BMD loss correlated with TT genotype by VDR gene but not with genotypes Tt and tt and associated with carriage of incomplete s-allele in the Col1a1 gene. Yet, in several instances high BMD loss rates were personified with carriers of VDR gene alleles (homo- and heterozygote states--tt and Tt) and heterozygote by Col1a1 gene (Ss).