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Beljan, J. R.

Publications and source records attributed to Beljan, J. R..

11 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

The effect of low light intensity on the maintenance of circadian synchrony in human subjects

The light-intensity threshold for humans is not known. In past space flights owing to power restrictions, light intensities have been minimal and reported to be as low as 15 ft. c. This study was conducted to determine whether the light (L)/dark (D) environment of 16L : 8D at the relatively low light intensity of 15 ft. c. was adequate for the maintenance of circadian synchrony in human subjects. Six healthy male subjects aged 20-23 years were exposed for 21 days to a 16L : 8D photoperiod. During the first 7 days the light intensity was 100 ft. c.; it was reduced to 15 ft. c. during the next 7 days and increased again to 100 ft. c. during the last 7 days of the study. Rectal temperature (RT) and heart rate (HR) were recorded continuously throughout the 21 days of the study. In the 100 ft. c. 16L : 8D the RT and HR rhythms remained stable and circadian throughout. When the light intensity was decreased to 15 ft. c. the periodicity of the HR rhythm was significantly decreased and this rhythm showed marked instability. In contrast the period of the RT rhythm did not change but a consistent phase delay occurred due to a delay in the lights-on associated rise in RT. These divergent effects on these two rhythms in internal desynchronization and performance decrement during the 15 ft. c. exposure. The data emphasize the need for establishing accurately the minimal lighting requirements for the maintenance of circadian rhythms of humans in confined environments.

Circadian Rhythm/physiology/radiation effects↗
NASA NTRS1977

Space motion sickness medications: interference with biomedical parameters

The possibility that drugs administered to Skylab 3 (SL-3) and 4 (SL-4) crewmen for space motion sickness may have interfered with their biomedical evaluation in space was investigated. Healthy volunteers received combinations of Scopolamine/Dexedrine for four days in regimens similar to those used in these missions. Urine samples, heart rate, body temperature, mood and performance were analyzed for drug-related changes. Twenty-four hour urine samples were analyzed by the same procedures as those used to analyze the flight samples. Hormone concentrations determined included cortisol, epinephrine, norepinephrine, aldosterone and antidiuretic hormone (ADH). In addition, volume, specific gravity, osmolarity, sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), chloride (Cl), inorganic phosphate, uric acid and creatinine were measured. Performance was not affected by the Scopolamine/Dexedrine. The drug combination increased daily mean heart rate (HR) significantly in all the subjects and daily mean rectal temperature (RT) in some of the subjects. A 2-4 hr phase shift in the HR circadian rhythm was also observed which indicates that internal circadian synchrony was disturbed by the drugs. Psychological and subjective evaluation indicated that the subjects could usually identify which days they were given the drugs by an increase in tension and anxiety, decreased patience, restlessness, decreased appetite, difficulty in sleeping and feelings of increased heart rate and body temperature. Urinary electrolytes were not changed significantly by the drug, but marked and significant changes occurred in urine volume and hormone excretion patterns. Scopolamine/Dexedrine caused consistent elevations in urinary cortisol and epinephrine and a transient elevation in ADH. Norepinephrine excretion was decreased, but there was no significant change in aldosterone excretion or in 24 hr urine volume. A comparison of these findings with the first four days of inflight data from the SL-3 and SL-4 missions leads to the conclusion that the dramatic increases in aldosterone excretion during the first three days of spaceflight probably can be directly attributed to weightlessness, whereas the antimotion sickness medication could have substantially contributed to the early increased excretion of epinephrine and cortisol during these missions.

manned↗
NASA NTRS1976

Space motion sickness medications - Interference with biomedical parameters

The possibility that drugs administered to Skylab 3 and 4 crewmen for space motion sickness may have interfered with their biomedical evaluation in space is investigated. The mixture of scopolamine and dextroamphetamine produced changes which allow a more valid interpretation of the early biomedical changes ocurring in weightlessness. There is no doubt that the dramatic increase in aldosterone excretion is not attributable to the drug, while the drug could have contributed to the in-flight changes observed in cortisol, epinephrine, heart rate and possibly urine volume.

Vernikos-Danellis, J.↗
NASA NTRS1976

The effect of low light intensity on the maintenance of circadian synchrony in human subjects

Experiments were conducted on six healthy male subjects aged 20-23 yr and exposed for 21 days in a confined regulated environment to 16L:8D light:dark cycle with a view toward determining whether the light environment of 16L:8D at the relatively low light intensity of 15 ft.c. is adequate for the maintenance of circadian synchrony in man. The light intensity was 100 ft.c. during the first seven days, reduced to 15 ft.c. during the next seven days, and increased again to 100 ft.c. during the last seven days. Rectal temperature (RT) and heart rate (HR) were recorded throughout the three phases. In the 100 ft.c. regime, the RT and HR rhythms remained stable and circadian throughout. It is shown that 15 ft.c. light intensity is at or below threshold for maintaining circadian synchrony of human physiologic rhythms marked by instability and internal desynchronization with degradation of performance and well-being.

Winget, C. M.↗
NASA NTRS1973

Flexible temperature probe for biological systems

Probe is sufficiently flexible so that it can be worn comfortably for long periods of time, but relatively rigid to permit easy insertion. Body and electrical leads of small thermistor are imbedded in flexible fluorosilicone matrix contained in vinyl plastic tubing.

Haro, P. J.↗
NASA NTRS1971

Effect of altered 'weight' upon animal tolerance to restraint.

The effect of altered weight upon animal tolerance to restraint was determined by simulating various accelerative forces with directed lead weights using restrained and nonrestrained domestic fowl (chickens). Weighting (increased weight) and conterweighting (reduced weight) produced a stressed condition - reduced relative lymphocyte counts, loss of body mass, and/or the development of a disorientation syndrome - in both restrained and nonrestrained (caged only) birds. The animal's tolerance to altered weight appeared to be a function of its body weight. Unrestrained birds were stressed by counterweighting (mean plus or minus standard error) 58.3 plus or minus 41% of their body weight, whereas restrained birds tolerated only 32.2 plus or minus 2.6% reduction in body weight. A training regimen for restrained birds was not effective in improving their tolerance to a reduced weight environment. It was concluded that domestic fowl living in a weightless (space) environment should be restrained minimally and supported by ventrally directed tension equivalent to approximately 50% of their body mass (their weight in a 1 G environment).

Burton, R. R.↗