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Biomedical subjects

Y Shapiro

Publications and source records attributed to Y Shapiro.

At least 91 records · Page 5Linked to original sources
PubMed1980

Dynamic changes in acid base balance during heatstroke in dogs.

The dynamic changes in acid base balance and respiratory metabolism during the development of heatstroke in dogs were studied. Three groups of five unanesthetized dogs each were exposed to different climatic conditions while at rest: A) 24 degrees C, 50% relative humidity (RH); B) 35 degrees C, 35% RH, and C) 45 degrees C , 25% RH. These conditions were maintained for 4 h or until the dogs collapsed. The heatstroke dogs were cooled in tap water bathes and were observed for another 4 h. Dogs of groups A and B did not show any notable changes in rectal temperature (Tre) and acid base balance. All dogs in group C developed heatstroke. Their peak mean Tre (44.1 degrees C) was reached after a mean of 111 min of exposure, with respiratory alkalosis followed by increasingly severe metabolic acidosis above Tre of 42 degrees C. At peak Tre mean arterial pH was 7.26. Acidosis increased (pHa = 7.17) following cooling, as panting subsided. At Tre above 42 degrees C blood lactate increased and bicarbonate decreased significantly, attaining mean values of 58 mg% and 8 mEq/l, respectively. Bicarbonate changes correlated linearly with lactate changes. During recovery lactate decreased and blood pH increased approximating normal by the end of the experiment. The results illustrate the body's ability to spontaneously correct arterial pH without therapeutic means.

Acid-Base Equilibrium↗
PubMed1980

Tap water, an efficient method for cooling heatstroke victims--a model in dogs.

Forty experimentally heatstroke dogs were cooled by immersion in water at temperatures varying from 1-25 degrees C. At all water temperatures, cooling occurred at a much slower rate in comatose dogs in conscious ones. Dogs cooled in tap water (15-16 degrees C) had the same cooling rate as those cooled in ice water (1-3 degrees C). At water temperatures above 18 degrees C, cooling rates were considerably decreased. Since tap water cooled as efficiently as ice water, its use may prove the method of choice for human heatstroke victims. Its advantages are ready availability, simplicity of use, and its failure to cause shivering.

Animals↗
PubMed1980

Physiological responses of men and women to prolonged dry heat exposure.

Heat-acclimated men (n = 10) and women (n = 9) were exposed to hot-dry conditions (49 degrees C, 20% rh) for 4h to determine the effect of prolonged work in the heat on physiological differences between the sexes. Hourly exposures consisted of 10 min resting and 50 min walking at 1.34 m . s-1 (time-weighted metabolic rate = 175 and 151 W . m-2 for men and women, respectively). No significant difference in rectal temperature (Tre) was found between the sexes for each hour (h) of exposure. Heart rate (HR) of women, however, averaged 10-17 beats . min-1 higher than men. Mean skin temperature (Tsk) was also significantly higher in women throughout the exposure. For both sexes, the 4th-h Tre, HR, and Tsk were significantly higher than the preceding 3h. No sex related differences in total sweat rate (msw) or sweat sensitivity, as indicated by msw/delta Tre, were evident. It was concluded that: a) prolonged exposure to dry heat does not accentuate physiological differences between the sexes; b) women sweat at rates comparable to men over a 4-h period; c) 2-h acclimation sessions do not necessarily acclimate individuals for work of longer duration.

Acclimatization↗
PubMed1979

The effect of exposure to heat on intraocular pressure.

During exposure to heat there is an increase of the intraocular pressure in nonacclimatized persons. This increase is not found after heat acclimatization has been carried out. The increase of the intraocular pressure in the nonacclimatized persons can be attributed to the increase of the body temperature due to insufficient sweating.

Acclimatization↗
PubMed1979

Heat intolerance in former heatstroke patients.

Nine young men who had suffered from heatstroke on previous occasions (heat-intolerant subjects) and 10 young volunteers (control subjects) were examined to determine their physiologic responses to exercise in temperate (23 degrees C) and hot environments (40 degrees C). The tests included an orthostatic test, work loads of 40 W and 80 W, and oxygen consumption (Vo2) determination. Although all the control subjects completed the exercise under severe heat load (3 h), none of the heat-intolerant subjects succeeded in completing this test due to high rectal temperatures and high heart rates. Sweat rates were similar in both groups, with Vo2 slightly higher in the control subjects. Orthostatic responses were similar in each group. The results suggest that inefficient thermoregulation, possibly due to decreased heat conductance from core to periphery, contributes to heat intolerance in former heatstroke patients.

Adult↗
PubMed1978

The effect of standardised submaximal work load on intraocular pressure.

A relatively small decrease in intraocular pressure secondary to submaximal work can be demonstrated when factors other than the work load itself are eliminated--diurnal variation, body position, and the effect of repeated examinations. A feedback mechanism that causes a return of IOP towards its normal value after work-induced decreases is postulated.

Adult↗
PubMed1978

Age and sex difference in response to short exposure to extreme dry heat.

Sixty volunteers, 33 males and 27 females (18-63 yr), were divided according to age and sex. They were exposed for 10 min to extreme dry heat: 80-90 degrees C dry bulb temperature and 3-4% relative humidity. Their rectal temperature, skin temperature at eight different points, weight, and heart rate were recorded prior to and immediately following the exposure. A mean rise of only 0.5 degrees C in rectal temperature was recorded following exposure as compared to a mean rise of 5.2 degrees C in mean weighted skin temperature (MWST). Female subjects showed a significantly higher rise in MWST than the male subjects. Similarly, a significantly higher rise in MWST was observed in elderly male subjects as compared to the youngest male group (P less than 0.05). The differences in MWST possibly resulted from differences in mean skin blood flow causing differences in skin conductance. Large individual variation in heat response was recorded in rectal temperature, as well as in weighted skin temperatures. The increase in skin temperature during the first 10 min of exposure to extreme dry heat may serve as an indicator for heat tolerance time, and may help predicting heatstroke susceptible individuals.

Adaptation, Physiological↗
PubMed1978

Rehabilitation of patients with NCA (neurocirculatory asthenia) through a short term training program.

Twenty-two patients, 18 years old, with the predominant somatic type of NCA, and a control group of 22 healthy subjects participated in a short term training course lasting three weeks. Following the training the NCA subjects showed a significant change in the systolic and diastolic blood pressure after 5 minutes of recumbency as well as in the systolic blood pressure after 5 minutes of standing, diastolic pressures during 50 W load and submaximal effort (100-150 W) - all the values being significantly lower following the training, except the diastolic pressure during 50 W load which was higher following the course. The prominent training effect was on the heart rate during light work loads (50 W) in which a decrease from a mean of 151.2 +/- 13.9 to 118.3 +/- 16.3 beats/min was recorded. This decrease indicates the better adaptation of the NCA patients to physical effort. Similarly, a significant increase in the mean VO2max from 31.5 +/- 6.1 to 37.7 +/- 5.9 ml O2/kg B.W./min was observed. No changes were recorded in the ECG after the short training course. Following the training all the symptoms typical of the NCA syndrome vanished. A short physical training of 3 weeks can start the procedure of rehabilitation of a well selected group of NCA patients with predominant somatic complaints. The rehabilitation must be continued throughout life by continued physical training.

Adolescent↗
PubMed1978

Orthostatic hypotension in amputees and subjects with spinal cord injuries.

Orthostatic examinations were performed with a tilt table on 64 male volunteers, of whom 21 had sustained amputation of one or both lower limbs and 23 were paraplegic due to spinal cord injuries (SCI), with 20 healthy subjects as controls. Following tilting, signs and symptoms of fainting appeared in five of the SCI subjects, four of whom had spinal injuries above the level of D5. These phenomena appeared in only two of the controls and in none of the amputees. The mean systolic and diastolic blood pressures of the amputees at rest and standing were higher than those recorded in the other two groups. The mean pulse pressures were lower in the amputees than in the other two groups. The changes in the systolic, diastolic, and pulse pressures were more profound in those subjects with high spinal cord injuries than in subjects with lower cord injuries. ECG changes and fainting were more frequent among the SCI subjects than in the other two groups.

Adult↗
PubMed1978

Optimal back-pack load for short distance hiking.

Twenty young men marched 6 and 12 km with a well-fitted back-pack load of 30 or 35 kg. Each subject served as his own control. No significant increase in mean heart rate, rectal temperature, or decrease in mean VO2 max and serum levels of glucose and muscle enzymes were recorded in the groups marching 6 km with 30 and 35 kg. Significant differences in the increases in mean heart rate, the decreases in VO2 max and the changes in blood glucose were noted between the two groups carrying 30 and 35 kg for 12 km. These significant differences were also supported by the subjective feelings of the volunteers. The present study shows the optimal back-pack load for healthy young men, marching at 6 km/hr on a paved level road to be 30 kg for 12 km and 35 kg for 6 km without considering the task too difficult and with no significant decrease in VO2 max. The results are relevant to hiking, rescue assignments, and military missions.

Adolescent↗
PubMed1978

Maximal oxygen uptake, heat tolerance and rectal temperature.

To determine the relation of rectal temperature (Tre) to Vo2max and heat tolerance, eight untrained, eight trained and five heat acclimated subjects (respective means +/- SE for Vo2max in ml/kg.min of 37.5 +/- 1.6; 55.7 +/- 1.5; and 54.5 +/- 3.2) were tested in 3 conditions: 60 min of exercise at a fixed load of 35 W at room temperature of 23 degrees C; 60 min of exercise at 35% Vo2max also at 23 degrees C, and 3-hr of exercise in heat (40 degrees C DB, 30 degrees C WB). The heat-acclimated group showed the best heat tolerance, while the untrained group showed the poorest responses in heat. Exercise at 35 W resulted in higher heart rates shown by the untrained, compared with the other subjects, while equilibrium Tre were 37.6, 37.9, and 38.2 degrees C, in the heat-acclimated, trained and untrained groups, respectively, with corresponding differences for resting Tre (36.7, 36.9, and 37.1 degrees C). During exercise at 35% Vo2max, the heat-acclimated group showed lower Tre than the trained group despite working at the same relative loads. Tre during exercise at 35 W at 23 degrees C correlated r = -70 with Vo2max and r = 0.80 with Tre during exercise in heat. These results show that Vo2max accounts for only part of the variability which determines the level of Tre in cool conditions with heat acclimatization accounting for the remainder of this relationship.

Acclimatization↗