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Biomedical subjects

C S Leach

Publications and source records attributed to C S Leach.

71 records · Page 4Linked to original sources
PubMedDate not supplied

Endocrine responses in long-duration manned space flight.

The bioassay of body fluids experiment is designed to evaluate the biochemical adaptation resulting from extended exposure to space flight environment by identifying changes in hormonal and associated fluid and electrolyte parameters reflected in the blood and urine of the participating crewmen. The combined stresses of space flight include weightlessness, acceleration, confinement, restraint, long-term maintenance of high levels of performance, and possible desynchronosis. Endocrine measurements to assess the physiological cost of these stresses have been considered from two aspects. Fluid and electrolyte balance have been correlated with weight loss, changes in the excretion of aldosterone and vasopressin and fluid compartments. The second area involves the estimation of the physiological cost of maintaining a given level of performance during space flight by analysis of urinary catecholamines and cortisol. Inter-individual variability was demonstrated in most experimental indices measured; however, constant patterns have emerged which include: body weight change; increases in plasma renin activity; elevations in urinary catecholamines, ADH, aldosterone and cortisol concentrations. Plasma cortisol decreases in immediate postflight samples with subsequent increase in 24-hour urines. The measured changes are consistent with the prediction that a relative increase in thoracic blood volume upon transition to the zero-gravity environment is interpreted as a true volume expansion resulting in an osmotic diuresis. This diuresis in association with other factors ultimately results in a reduction in intravascular volume, leading to an increase in renin and a secondary aldosteronism. Once these compensatory mechanisms are effective in reestablishing positive water balance, the crewmen are considered to be essentially adapted to the null-gravity environment. Although the physiological cost of this adaptation must reflect the electrolyte deficit and perhaps other factors, it is assumed that the compensated state is adequate for the demands of the environment; however, this new homeostatic set is not believed to be without physiological cost and could, except with proper precautions, reduce the functional reserve of exposed individuals.

Adaptation, Physiological↗
PubMedDate not supplied

An overview of the endocrine and metabolic changes in manned space flight.

In the years since the Skylab Program, endocrinology and metabolism have gone through stages of development that can be characterized as descriptive, both physiological and biochemical. At the present time, this area demonstrates a significant increase in knowledge of endocrine and metabolic function in physiology and pathology at the biochemical level. The development of sensitive techniques for the measurement of hormones, their precursors and metabolites and the increasing amount of information on integrated endocrine responses in various physiologic processes make it valuable for us to retrospectively consider our space flight findings especially in considering future work.

Adaptation, Physiological↗
PubMedDate not supplied

Collagen breakdown and nitrogen dioxide inhalation.

Measurements of urinary hydroxylysine glycosides indicate that considerable collagen degradation occurred during the reentry into the earth's atmosphere of the American astronauts of the Apollo-Soyuz mission. Since the crew accidentally inhaled nitrogen dioxide, a recognized pulmonary irritant, and showed clinical and roentgenographic signs of diffuse chemical pneumonitis, it is likely that collagen degradation occurred in the pulmonary parenchyma.

Collagen↗
PubMedDate not supplied

Collagen breakdown and ammonia inhalation.

Measurement of several urinary metabolites of hydroxylysine indicates that considerable collagen degradation occurred in four individuals immediately after they had inhaled concentrated ammonia vapors. Since clinical and/or radiological evidence of intense upper respiratory and pulmonary inflammation were evident, it is likely that collagen degradation occurred at the level of the respiratory system.

Adolescent↗
PubMedDate not supplied

[Principles of NASA longitudinal medical studies].

This paper describes approaches to longitudinal studies of the changes in the health status of the US astronauts. The methods include acquisition and analysis of biomedical data accumulated in one and repeated space missions, detection of potential occupational diseases inflight and evaluation of mortality cases associated with them. It is suggested to use pilots and flight controllers as controls. It is indicated that annual physical examinations can be an important source of relevant scientific information.

Adult↗
PubMedDate not supplied

[Medical results from STS 1-4: analysis of body fluids].

Venous blood was drawn from the eight crewmembers of Space Shuttle flights STS-1 through STS-4 three times before lift-off and twice after landing, and the characteristics of biomedical blood components were evaluated. Twenty-four-hour urine pools were collected 30 days before flight and on landing day or day 4 after landing, and electrolytes, selected hormones and other components were measured. The results indicated that although fluid and electrolyte losses occur during space flight, conservation of these substances is begun almost immediately upon cessation of weightlessness. Enzyme and hormone measurements indicated that landing may have caused some stress on crewmembers.

Blood Chemical Analysis↗