Search PubMed⌕ Search

Biomedical subjects

C M Winget

Publications and source records attributed to C M Winget.

At least 37 records · Page 2Linked to original sources
PubMed1976

Psychologic and psychophysiologic response to 105 days of social isolation.

The responses of nine subjects to 105 d of social isolation are reported. The study reveals that crew selection plus ongoing support by psychiatric staff permits continued function in an exotic milieu. Prediction of psychophysiologic symptoms was possible using paper and pencil tests. Trait anxiety was altered by the isolation in a psychologically healthy direction. Sudden time shifts of 8 h led to an immediate significant increase in depression, aggression, and hostility, and are accompanied by marked increases in physical symptoms. During the first free-running phase of the experiment, significant shifts were found on four psychological measures. The shifts indicate that subjects became less trusting, more orderly, more routinized, less energetic, and more depressed. A reducer-augmenter scale predicted the number of psychophysiologic complaints reported by individual subjects while isolated. A group interaction effect on circadian rhythms was isolated but needs further examination.

Adult↗
PubMed1975

Response of mice to repeated photoperiod shifts: susceptibility to stress and barbiturates.

Three inbred strains of mice selected for their spontaneous aggressive behavior and differential susceptibility to stress were exposed to a controlled environment where on an average of once every 4 days for 76 days and subsequently on an average of once every 2 days for an additional 55 days a 12L:12D photoperiod was reversed by 180 degrees. This procedure did not affect the growth of the mice and appeared to reduce fighting. However, plasma corticosterone concentrations in all three strains of mice were high, and their response to a 24-hr cold stress was no longer evident. The most pronounced effect of the altered photoperiod was on the barbiturate-induced sleeping time which showed a 40% reduction in all strains in spite of differential suceptibility to the drug among strains. It is concluded that repeated random phase shifting by varying the photoperiod is a stressful experience to which animals do not adapt and that the ability to respond to an additional stimulus or drugs may be greatly altered.

Aggression↗
PubMed1970

Diurnal rhythm of the pituitary-adrenocortical response to stress: effect of constant light and constant darkness.

The existence of a biological rhythm in the response of animals to noxious stimuli and drugs is well known. However, the mechanism of this response is not well understood. This study was undertaken to describe the existence of a diurnal rhythm in the hypothalamic-pituitary-adrenocortical system before and after stress in female rats kept in controlled environmental conditions in 12L:12D, 24L:OD, or OL:24D. Plasma ACTH and plasma corticosterone concentrations were compared in unstressed animals. The time pattern in the response to stress was determined at four hourly intervals during a 24 hr period in which plasma ACTH and plasma corticosterone were measured at different time intervals. The stress response varied considerably with time of day in both magnitude and duration. The adrenals of rats exposed to constant light for 45 days atrophied, whereas the adrenals of animals kept in constant dark for the same period did not differ significantly from those of controls kept in 12L:12D. The increase in plasma ACTH in response to stress was greater both in the animals maintained in constant light and in constant dark than in the 12L:12D controls. Homeostatic mechanisms involved in these changes are discussed.

Adrenal Glands↗
PubMed1970

Mechanisms of action of light on circadian rhythms in the monkey.

Light is considered by many investigators to be the primary Zeitgeber for most physiologic rhythms. In order to study the effects on biorhythms of changing photoperiods and to provide information on the nature of the wave forms and the mechanisms of entrainment, unrestrained male monkeys (Cebus albifrons, Macaca nemestrina) were maintained in a sound-proofed environmental chamber. The Cebus was initially maintained on a 12L:12D schedule; it was subjected to a 180 degrees phase shift for 14 days, then returned to the original photoperiod. In two experiments (24 days; 27 days each) the same monkey was again maintained on a 12L:12D schedule which was gradually altered to a constant light environment. Deep body temperature (DBT) data were obtained with miniature radiotransmitters. Locomotor activity (LMA) was measured by strain gauges. Under the 12L:12D regimens the Macaca DBT cycles were uniform as to phase and wave form for over 60 weeks. These wave forms were analyzed by the use of periodogram and correlogram analyses and by fitting to the Volterra Integro-Differential Equation. Phase angle relationships between Zeitgeber and physiologic parameters were characterized. After the photoperiod phase shift the DBT cycle rephased in about 9 days. During the rephasing process the wave form changed. The shapes of the wave forms of DBT and activity were maintained with increasing light until an 18L:6D photoperiod was reached. The rhythms were entrained to the onset of darkness rather than lights on. Major and minor periods of LMA were detected. Hysteresis diagrams showed that DBT led the onset of major LA by 6 hr and the end of major activity by 2 hr.

Animals↗
PubMed1967

Daily rhythm changes associated with variations in light intensity and color.

Asynchronosis with its symptoms of fatigue, confusion, and discomfort is perhaps the most frequently experienced problem of jet travel; and without synchronization it will represent a major problem with supersonic and interplanetary travel. Current observations suggest that light is the most important environmental factor for the regulation of daily rhythms. Therefore, the purpose of this study was to quantitatively evaluate daily rhythm changes associated with changes in light intensity at given wavelengths of light. Biological rhythm data of birds have been useful for the interpretation of data collected on man. Two normal chickens were used to study three daily physiological rhythms in a controlled environment for approximately 80 days. Variables included the light intensity and wavelength. Heart rate, deep body temperature, and activity were recorded at 6 min intervals. The first two measurements were received from miniature radio transmitters and the third directly from the cage floor. The presence of the cycles was established by periodogram and correlogram analysis. The data were described further by harmonic regression analysis and cross correlations between the three daily rhythms. The physiologic systems studied are arrhythmic in continuous red light. There was no change observed in the periods of the daily rhythms with an increase in light intensity. Deep body temperature oscillations were greater at the higher light intensities and appeared to dissociate from heart rate. Activity and heart rate have a high degree of correlation even at the higher intensities.

Animals↗