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Biomedical subjects

J J Hauser

Publications and source records attributed to J J Hauser.

5 recordsLinked to original sources
PubMed1991

Influence of ventilation of the face on thermoregulation in man during hyper- and hypothermia.

It has been suggested that a thermal countercurrent exchange may occur in the cerebral vascular bed of humans, thereby creating for the brain a state of relative thermal independence with regard to the rest of the body. However, worrying questions have arisen concerning this suggestion. Experiments were carried out on seven young male volunteers. Hyper- and hypothermic conditions were produced by immersion in water at 38.5 degrees C and 25 degrees C, respectively. During the last few minutes of immersion, the face was cooled or warmed by ventilation with a 200 l.min-1 air flow at 5 degrees C or 40 degrees C, respectively. Internal and peripheral temperatures were recorded. Blood flow in the anastomotic vessels between face and brain was measured by Doppler techniques associated with computerized frequency analysis. The general responses were as classically described, i.e. an increase in peripheral and central temperatures during immersion in the warm bath and a decrease in these variables in the cold bath. The reactions produced by cooling or warming the face were small and easily explained by the direct changes of the heat load they induced. Whatever the thermal conditions, the blood flow in the anastomotic vessels between the vascular bed of the face and that of the brain was never reversed. It was concluded that there was no experimental evidence for an efficient thermal counter-current exchange in the vascular bed of the human head.

Adult↗
PubMed1987

Effect of voluntary dehydration on thermoregulatory responses to heat in men and women.

The effects of dehydration prior to heat exposure on sweating and body temperature were tested in 8 men and 8 women, dehydration being 1.3 and 1.0% of body weight, respectively. The subjects were exposed to 40 degrees C for 60 min. Compared with controls (C), in the dehydrated men (D) there was a longer delay in the onset of sweating (C, 7.8, D, 11.6 min, p less than 0.05), a lower total sweat loss (C, 153, D, 127 g X m-2 X h-1, p less than 0.001), and a greater increase in Tre (C, 0.31, D, 0.43 degree C, p less than 0.002). In women, dehydration did not influence the control time course of sweating significantly, nor were these significant body temperature increases during heat exposure. Delay in the onset of sweating in women (C, 18.1, D, 18.7 min) was generally longer than in men (C, 7.8, D, 11.6 min), [F(1,14) = 7.41, p less than 0.05]. A significant correlation was found between the inertia time of sweating and delta Tre in both control and dehydration conditions in the men (r = 0.81, p less than 0.01). The rectal temperature increases in men were also related to the inertia time of electrical skin resistance (r = 0.83, p less than 0.01). It is concluded that dehydration affects sweating and body temperature in men more severely than in women.

Adult↗
PubMed1985

Dynamics of sweating in men and women during passive heating.

The dynamics of sweating was investigated at rest in 8 men and 8 women. Electrical skin resistance (ESR), rectal temperature (Tre) and mean skin temperature (Tsk) were measured in subjects exposed to 40 degrees C environmental temperature, 30% relative air humidity, and 1 m X s-1 air flow. Sweat rate was computed from continuous measurement of the whole body weight loss. It was found that increases in Tre, Tsk and mean body temperature (Tb) were higher in women than in men by 0.16, 0.38 and 0.21 degrees C, but only the difference in delta Tb was significant (p less than 0.05). The dynamics of sweating in men and women respectively, was as follows: delay (td) 7.8 and 18.1 min (p less than 0.01), time constant (tau) 7.5 and 8.8 min (N.S.), inertia time (ti) 15.3 and 26.9 min (p less than 0.002), and total body weight loss 153 and 111 g X m-2 X h-1 (p less than 0.001). Dynamic parameters of ESR did not differ significantly between men and women. Inertia times of ESR and sweat rate correlated in men (r = 0.93, p less than 0.001), and in women (r = 0.76, p less than 0.02). In men, delta Tre correlated with inertia time of sweat rate (r = 0.81, p less than 0.01) as well as with the inertia time of ESR (r = 0.83, p less than 0.001). No relation was found between delta Tre and the dynamics of sweating in women. It is concluded that the dynamics of sweating plays a decisive role in limiting delta Tre in men under dry heat exposure. The later onset of sweating in women does not influence the rectal temperature increase significantly. In women, delta Tre is probably limited by a complex interaction of sweating, skin blood flow increase, and metabolic rate decrease.

Adult↗
PubMed1984

A closed anesthetic system for small laboratory animals.

An anesthetic unit was developed that maintained adequate anesthetic levels, removed carbon dioxide, and contained gases. The device produced inhalation anesthesia in both small mammals and birds by using either halothane or methoxyflurane.

Anesthesia, Inhalation↗