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Rambaut, P. C.

Publications and source records attributed to Rambaut, P. C..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Biochemical responses of the Skylab crewmen: An overview

Continuous metabolic and endocrinic monitoring of Skylab crewmen established significant biochemical changes that varied in magnitude and direction but disappeared shortly after return to earth. These changes indicate adaptation by the body to the combined stresses of weightlessness. Transient changes in fluid and electrolyte metabolisms lead to the conclusion that a homeostasis condition had been achieved. Unstable states persisted in the metabolisms of bone mineral, protein, and carbohydrates.

Leach, C. S.↗
NASA NTRS1977

Metabolic energy requirements during manned orbital Skylab missions

The metabolic balance of nine Skylab astronauts was studied during the course of 28-, 59-, and 84-day flights. Control periods of at least three weeks preceding each flight and at least 18 days following each flight were included in the metabolic studies. Results of the investigation indicated that all members lost mass in flight without experiencing an increase in body density. Analysis of bone density, blood and urinary nitrogen levels, and overall calcium and nitrogen balances suggested that lean body mass declined through loss of protein. It thus appeared that despite adequate energy intake, the crew members did not reach equilibrium with the weightless environment within the time periods studied.

Rambaut, P. C.↗
NASA NTRS1977

Skylab nutritional studies

Precise nutritional specifications arising from both physiological and experimental requirements necessitated a comprehensive study of the chemical composition of the Skylab food supply. Each of the approximately seventy different food items was analyzed for digestible and non-digestible carbohydrate, and for protein, amino acids, fat, fatty acids, vitamins and minerals. Menus were formulated to provide at least the National Research Council's Recommended Dietary Allowance of all essential nutrients and, in addition, to provide constant daily intakes of calcium, phosphorus, magnesium, sodium, potassium and protein. In general, the crew members adhered to their programmed menus. The ability to swallow and digest food was unaffected by prolonged weightlessness. Taste acuity also appeared to be undiminished in flight. The bone and muscle changes which occurred in previous flights were more pronounced in Skylab. It is concluded that these changes did not develop as a result of nutritional deficit. If such changes are nutritionally related, they point to the existence of nutritional requirements in weightlessness which differ quantitatively from those observed on earth.

long duration↗
NASA NTRS1976

Changes in glucose, insulin, and growth hormone levels associated with bedrest

Changes in plasma glucose, insulin, and growth hormone (HGH) resulting from exposure to 56 d of bedrest were determined in five healthy young male subjects. Changes in the daily levels of these factors for each subject were expressed as the mean of six blood samples per 24-h period. The level of HGH dropped after 10 d of bedrest, then showed a 1.5-fold increase at 20 d and subsequently decreased gradually reaching levels of 2.5 mg/ml/24 h, well below pre-bedrest controls of 4.2 mg/ml/24 h, by the 54th d. In spite of a marked increase in the daily plasma insulin levels during the first 30 d of bedrest, glucose levels remained unchanged. Beyond 30 d of bedrest, insulin began decreasing toward pre-bedrest levels and glucose followed with a similar reduction to below the control levels of 75 mg/100 ml/24 h on day 54. The daily mean changes reflect a change in the amplitude of the diurnal variation. The daily peak in plasma insulin shifted progressively to the late evening during the bedrest period.

Vernikos-Danellis, J.↗
NASA NTRS1976

Skylab nutritional studies

Precise nutritional specifications arising from both physiological and experimental requirements necessitated a comprehensive study of the chemical composition of the Skylab food supply. Each of the approximately 70 different food items was analyzed for digestible and nondigestible carbohydrate, and for protein, amino acids, fat, fatty acids, vitamins, and minerals. Menus were formulated to provide at least the National Research Council's Recommended Dietary Allowance of all essential nutrients and, in addition, to provide constant daily intakes of calcium, phosphorus, magnesium, sodium, potassium and protein. In general, the crewmembers adhered to their programmed menus. The ability to swallow and digest food was unaffected by prolonged weightlessness. Taste acuity also appeared to be undiminished inflight. The bone and muscle changes which occurred in previous flights were more pronounced in Skylab. It is concluded that these changes did not develop as a result of nutritional deficit. If such changes are nutritionally related, they point to the existence of nutritional requirements in weightlessness which differ quantitatively from those observed on earth.

Rambaut, P. C.↗
NASA NTRS1976

Mineral and nitrogen balance study observations - The second manned Skylab mission

A metabolic study of important body elements, particularly those of the musculoskeletal system, was carried out on the astronauts of the Skylab 3 mission during the preflight, inflight, and postflight phases. An elevation in the level of urinary calcium similar to that observed in the 28-d Skylab flight continued throughout the flight. Significant nitrogen and phosphorus losses, apparently associated with muscle tissue loss, occurred in spite of inflight exercise programs. On the basis of these results it is predicted that capable musculoskeletal function is likely to occur in flights longer than about 9 months in duration.

Whedon, G. D.↗
NASA NTRS1976

Metabolic and endocrine studies - The second manned Skylab mission

Complete metabolic collections were performed on the Skylab 3 crew in the preflight, inflight, and postflight phases of the mission. Changes in fluid and electrolyte balance have been correlated with weight loss, changes in the excretion of aldosterone, vasopressin, and fluid compartments. The initial changes observed were consistent with an increase in thoractic blood volume upon transition to a zero gravity environment, producing a net fluid loss. Compensatory mechanisms reestablished positive water balance. The indicators investigated returned to thin preflight levels during the recovery period postflight

Leach, C. S.↗
NASA NTRS1975

Endocrine responses in long-duration manned space flight

Endocrine measurements to assess the physiological cost of the combined stresses of space flight are considered from two aspects. First, fluid and electrolyte balance are correlated with weight loss, changes in the excretion of aldosterone and vasopressin and fluid compartments. The second area involves 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 is demonstrated for most experimental indices measured. The measured changes are consistent with the hypothesis that a relative increase in thoracic blood volume upon transition to the zero-gravity environment can be interpreted as a true volume expansion resulting in an osmotic diuresis.

Leach, C. S.↗
NASA NTRS1975

Effect of potassium depletion in normal males - An Apollo 15 simulation

In the course of Apollo 15, physiologic abnormalities, manifested by ectopic activity on the ECG and unusual alterations in exercise tolerance, occurred in the crew of the Lunar Excursion Module. These were associated with decreases in total body potassium, measured by K-42, of 10% and 15%. The possibility of inadequate potassium (K+) intake existed. A simulation study was performed prior to Apollo 16, corresponding in duration to Apollo 15. Subjects endured the same sleep aberrations and caloric expenditure as the Apollo 15 astronauts. Subjects consumed a diet containing only 15 mEq/d of K+ during the entire 12 days of absolute bedrest. Study implications and reasons for discrepancies between K+ loss measured by balance techniques and K-42 are reviewed.

Hyatt, K. H.↗
NASA NTRS1974

Biochemical responses of the Skylab crewman

The biochemical investigations of the Skylab crewmen were designed to study the physiological changes that were observed on flight crews returning from previous space flight missions as well as to study those changes expected to result from prolonged weightless exposure. These studies can be divided into two broad categories. One category included routine blood studies similar to those used in clinical medical practice. The second included research-type endocrine analyses used to investigate more thoroughly the metabolic/endocrine responses to the space flight environment. The premission control values indicated that all Skylab crewmen were healthy and were free from biochemical abnormalities. The routine results during and after flight showed slight but significant changes in electrolytes, glucose, total protein, osmolality, uric acid, cholesterol, and creatinine. Plasma hormal changes included adrenocorticotrophic hormone, cortisol, angiotensin I, aldosterone, insulin, and thyroxine. The 24-hour urine analyses results revealed increased excretion of cortisol, catecholamines, antidiuretic hormone, and aldosterone as well as excretion of significant electrolyte and uric acid during the Skylab flights.

Leach, C. S.↗
NASA NTRS1974

Apollo experience report: Food systems

Development, delivery, and use of food systems in support of the Apollo 7 to 14 missions are discussed. Changes in design criteria for this unique program as mission requirements varied are traced from the baseline system that was established before the completion of the Gemini Program. Problems and progress in subsystem management, material selection, food packaging, development of new food items, menu design, and food-consumption methods under zero-gravity conditions are described. The effectiveness of various approaches in meeting food system objectives of providing flight crews with safe, nutritious, easy to prepare, and highly acceptable foods is considered. Nutritional quality and adequacy in maintaining crew health are discussed in relation to the establishment of nutritional criteria for future missions. Technological advances that have resulted from the design of separate food systems for the command module, the lunar module, The Mobile Quarantine Facility, and the Lunar Receiving Laboratory are presented for application to future manned spacecraft and to unique populations in earthbound situations.

Smith, M. C., Jr.↗
NASA NTRS1974

Adrenocortical responses of the Apollo 17 crew members

Changes in adrenal activity of the three Apollo 17 crew members were studied during the 12.55-day mission and during selected post-recovery days. Aldosterone excretion was normal early and elevated later in the mission, probably causing a loss in total body exchangeable potassium. There was decreased 17-hydroxycorticosteroid excretion only during the early mission days for the two moon landers and throughout the mission for the other astronaut. Cortisol excretion was elevated on physically stressful mission days. At recovery, plasma ACTH was elevated without a similar increase in plasma cortisol. Angiotensin I activity was elevated at recovery in only one crewman. This crewman was the only one with a decreased extracellular fluid volume. These results indicate that the mission and its activities affect adrenal function of the crewmen.

Leach, C. S.↗
NASA NTRS1974

Circadian, endocrine, and metabolic effects of prolonged bedrest: Two 56-day bedrest studies

Two bedrest studies of 56 days each have been conducted to evaluate the effects of prolonged bedrest on circadian synchrony and endocrine and metabolic function. Measurements included the pituitary-adrenal, thyroid, parathyroid, insulin-glucose-growth hormones, catecholamine excretion, body temperature, and heart rate. The results indicated that a rigorous regimen of exercise did not prevent the endocrine and metabolic effects of prolonged bedrest. Changes in circadian, endocrine, and metabolic functions in bedrest appear to be due to changes in hydrostatic pressure and lack of postural cues rather than to inactivity, confinement, or the bleeding schedule. Prolonged bedrest, particularly beyond 24 days, resulted in rhythm desynchronization in spite of well regulated light/dark cycles, temperature, humidity, activity, and meal times and meal composition and in increased lability of all endocrine parameter measured. It also resulted in an apparent insensitivity of the glucose response to insulin, of cortisol secretion to ACTH, and of growth hormone secretion to hypoglycemia.

Vernikos-Danellis, J.↗
NASA NTRS1974

Bone mineral measurement from Apollo experiment M-078

Loss of mineral from bone during periods of immobilization, recumbency, or weightlessness is examined. This report describes the instrumentation, technique, and bone mineral changes observed preflight and postflight for the Apollo 14, 15, and 16 missions. The bone mineral changes documented during the Apollo Program are reviewed, and their relevance to future missions is discussed.

Vogel, J. M.↗
NASA NTRS1973

The effect of bedrest on adrenal function

Eight male subjects were subjected to continuous bedrest for 24-80 weeks for the purpose of studying metabolic responses. Three of the subjects did supine exercises daily during part of the study. Adrenal function was examined in relation to adrenal cortical and medullary excretions. The results reveal an increase in hydrocortisone throughout the test period, a decrease in norepinephrine and no change in epinephrine. These data suggest that exercise could decrease the severity of deconditioning caused by bedrest.

Leach, C. S.↗
NASA NTRS1973

Estimates of fluid and energy balances of Apollo 17

Fluid and caloric balance has been calculated for the Apollo 17 crew. This included measurement of nitrogen, water, and caloric value of the ingested food and the volume and nitrogen content of the excreted urine and feces. Body composition changes were determined from total body water and extracellular fluid volume differences. The body composition measurements made it possible to divide the weight loss into lean body mass and adipose tissue losses. From this division a caloric equivalent was calculated. These tissue losses indicated that the caloric requirements of the mission were considerably greater than the actual caloric intake. The 3.3 kilo mean loss of body weight represented 1 kilo of lean body mass and 2.3 kilos of adipose tissue. Calculated fluid balance was more positive during the mission than during the control period. These changes are unlike the body composition and fluid balance changes reported in bedrested subjects.

Johnson, P. C.↗
NASA NTRS1973

Caloric balance during simulated and actual space flight

The in-flight caloric intakes of all Apollo astronauts are examined and shown to average about 25 kcal per kg per day. Measurement of weight changes following recovery indicates that about 0.15 kg of fat was lost per man per day in-flight for an average deficit of about 19 kcal per kg per day. Measurement of the caloric intake of astronauts under ground-based conditions and during hypobaric exposure indicated a caloric requirement which was not significantly different from the in-flight requirement adjusted for weight loss. Partial metabolic balance data and measurements of bone loss and body volume revealed that protein and mineral losses also occurred to an extent which would reduce the size of estimated in-flight caloric deficits.

Rambaut, P. C.↗