Circadian changes in man's thermoregulating responses were studied in two experimental runs during which 7 volunteer subjects were exposed at 8 equally spaced time points of the 24-h span to a quick rise in temperature (To = 40 degrees C, v = 1 m/sec, P H2O less than 1 kPa) or to progressive cooling, the final temperature being reached after 45 min (To = 20 degrees C, v = 0.2 m/sec, P H2O less than 1 kPa). Under heat exposure, a circadian rhythm was observed in the period preceding the onset of sweating, and also in rectal temperature and mean body temperature, both at the onset of sweating and at its steady state. The time constant of the sweating rate and the sweating rate at the steady state show no apparent changes. Under cold exposure there is no detectable circadian rhythm in the mean body temperature at the onset of shivering, however, a circadian evolution appears in rectal temperature at the onset of shivering and at the end of the experiment. A circadian rhythm also appears for the metabolic response at the end of the experiment. These results suggest the presence of a circadian rhythm of the set point with no change in the gain of sweat responses. They also imply that thermoregulating responses to cold follow circadian changes.

Body Temperature↗

PubMedDate not supplied

Circadian rhythm of temperature in man. Comparative study with two experiment protocols.

The circadian rhythm of rectal and skin temperature was studied in man at rest and at thermal neutrality according to two different protocols, to make allowance for the experimental conditions. In the first case, ambient temperature (To) was maintained at a constant value close to thermal neutrality and mean skin temperature (Ts) could evolve freely for 24 h. In the second case, Ts was maintained at 34 degrees C by adequately adjusting To during 90 min-periods divided into 8 equidistant points of the 24-h spans. The results were comparable and brought out a rhythm of rectal temperature (Tre) of a low amplitude, non sinusoidal, with a day-time plateau and a night-time minimum. The Ts and body conductance rhythm, the lack of metabolism and evaporative thermolysis rhythm led to us to confer a major role to the circulatory phenomena to explain the Tre rhythm in these experiments.

Adult↗

PubMedDate not supplied

[Airports malaria: findings of a survey in Paris airports (author's transl)].

From 1976 to 1978, thirteen cases of malaria have been reported from France. Ten of them occurred in the vicinity of the airport Roissy-Charles de Gaulle. The entomological investigation which is described there have been performed to evaluate risk of local transmission and to plan prophylactic measures.

Aircraft↗