Disseminated Intravascular Coagulation in Experimental Heatstroke

Heatstroke was induced experimentally in dogs, in order to clarify the mechanism of haemorrhage in that disorder.

Controls were provided both by dogs subjected to maximal effort at normal ambient temperatures and by dogs exposed to high enviromental temperature without exercise.

It was found that above a critical temperature (43.3° C), dogs show a typical clinical and laboratory picture of heatstroke, similar to that occurring in human beings.

Quick value and platelets dropped markedly, as did most of the clotting factors including factor V, II, VII and X.

Factor VIII was sometimes raised, but also fell terminally. Significant fibrinolysis and shortened half life of labelled fibrinogen were further strong indications of general defibrination.

The post-mortem presence of thrombi, provided confirmatory evidence of diffuse intravascular clotting (consumption coagulopathy).

Peripartum anesthetic management of a patient with brittle cornea syndrome

Brittle cornea syndrome (BCS) is a rare autosomal recessive disease that affects the connective tissue. The syndrome is caused by genetic changes in the 4.7-Mb interval between the D16S3423 and D16S3425 markers on the 16q24 chromosome and mutations in the Zinc-Finger 469 gene (ZNF469). BCS is characterized by thin and fragile cornea that tends to perforate spontaneously or as a result of minor trauma to the eye. In addition, the patient usually suffers from hearing loss, mental retardation, hyperextensibility of skin and joints, as well as varying degrees of scoliosis. This phenotypical expression presents an interesting challenge to anesthetic care. We briefly present the perioperative management of a patient with BCS who underwent three cesarean sections.

The association between the renin-angiotensin-aldosterone system and arterial stiffness in young healthy subjects

Aldosterone might affect arterial stiffening, in both the short- and long-term. We investigated a possible association between excess aldosterone, reflected by an increased aldosterone : renin ratio (ARR) and pulse wave velocity (PWV) in young healthy adults. In a single-centre study, 60 subjects were evaluated for lipid profile, glucose, hs-CRP, renin and aldosterone. PWV was performed as a simple non-invasive recording and computer analysis of the two artery sites pressure waveform using SphygmoCor (version 7.1, AtCor Medical, Sydney, Australia). The ARR was significantly, positively associated with PWV: r = 0.298, P = 0.02. ARR was not associated with anthropometric variables, blood pressure (BP), metabolic and inflammatory parameters. In conclusion, the ARR was significantly associated with PWV and may exhibit direct effects of aldosterone on the vascular wall, which are not related to changes in conventional cardiovascular risk factors.

Psoriasis and diabetes: a population-based cross-sectional study

BACKGROUND

Previous reports have shown an association between psoriasis and the metabolic syndrome, but there are only a few studies on the association between psoriasis and diabetes.

OBJECTIVES

To study the association between psoriasis and diabetes.

METHODS

A cross-sectional study was performed utilizing the database of Clalit Health Services (CHS). Patients who were diagnosed with psoriasis were compared with CHS enrolees without psoriasis regarding the prevalence of diabetes. Patients with diabetes were identified using the CHS chronic diseases registry. Chi-squared tests were used to compare categorical parameters. Logistic regression models were used for multivariate analyses.

RESULTS

The study included 16 851 patients with psoriasis and 74 987 subjects without psoriasis (control patients). The proportion of diabetes was significantly higher in patients above 35 years (P < 0.05). The age-adjusted proportion of diabetes was significantly higher in psoriasis patients as compared to the control group [odds ratio (OR), 1.38, P < 0.05] and was similar in men and women (OR, 1.32, 1.45, respectively). A multivariate logistic regression model showed that psoriasis was significantly associated with diabetes, independently of age and gender (OR, 1.58, P < 0.001).

CONCLUSIONS

Our study supports previous reports of an association between psoriasis and diabetes. Dermatologists taking care of patients with psoriasis should be aware of this association and advise the patients to reduce additional risk factors such as smoking, hypertension or dyslipidemia.

Changes in heart rate variability following acclimation to heat

We studied the sympatho-vagal balance during acclimation to heat in eight healthy individuals. The subjects, dressed in shorts and tennis shoes, underwent a 10 d procedure of acclimation. Daily exposure lasted 115 min--5 min rest followed by 2 bouts of 50 min exercise (walking on a treadmill at a work load of approximately 350 watt) separated by 10 min rest-at 40 degrees C and 40% relative humidity. We analyzed the time and frequency domains of 256 R-R intervals, toward the end of the second bout of exercise, on the first and tenth days of acclimation. Typical changes for heat acclimation (a reduction in rectal temperature and heart rate, an increase in sweat rate) were observed. Concomitant to a decrease in the final heart rate on the tenth day, sympathetic tone increased. We suggest that, except for the chronotropic response, changes in the sympatho-vagal balance may reflect several adaptive mechanisms of the cardiovascular system. Peripheral factors rather than intrinsic cardiac factors are of relatively greater importance in the direct control of cardiac function.

Peripheral target contact regulates Ca2+ channels in the cell bodies of bullfrog sympathetic ganglion B-neurons

Tyrosine-hydroxylase immunohistochemistry demonstrated that a single injection of 120 mg/kg 6-hydroxydopamine (6-OHDA) reversibly disconnected bullfrog sympathetic ganglia from their peripheral targets. This was correlated with a decrease in sympathetic outflow to the eyes and a reversible decrease in pupil diameter. 6-OHDA did not damage the cell bodies of ganglionic neurons. Calcium channel current in ganglionic B-neurons, (measured at -10 mV; holding potential -60 mnV; Ba2+ as charge carrier; IBa) was reduced. It reached a minimum of about 40% of control amplitude 7-14 days after 6-OHDA injection and recovered to 73% of control amplitude after 63 days. 6-OHDA induced loss and recovery of functional sympathetic innervation of peripheral target tissues, as determined by measurement of pupil diameter, occurred at a similar rate. Thus, pupil diameter attained mininum values 7-14 days after 6-OHDA treatment and recovered to 81% of control after 63 days. The properties of Ca2+ channels in sympathetic neurons are, therefore, determined by continuity of contact with peripheral target. 6-OHDA also decreased the peak amplitude and duration of the afterhyperpolarization (a.h.p) that follows the action potential (a.p.). The rate of recovery of a.h.p duration was more rapid than the rate of recovery of peak a.h.p. amplitude. This may reflect known differences in properties of two types of Ca2+-sensitive K currents. IC and IAHP, IC, which is responsible for the peak amplitude of the a.h.p has a low affinity for Ca2+, whereas IAHP, which determines a.h.p. duration, has higher Ca2+ affinity.

The cumulative heat strain index--a novel approach to assess the physiological strain induced by exercise-heat stress

The cumulative heat strain index (CHSI) is a new approach for assessing the total physiological strain experienced by subjects exposed to an exercise-heat stress. The index is based on inherent physiological logic that combines the thermoregulatory strain, which is described by the area under the hyperthermic curve, and the circulatory strain, which is characterized by heart-beat count. According to this model, the index reflects the dynamics of changes in the thermoregulatory and cardiovascular components and accounts for the complementary nature of the interaction between them. Mathematically, the index is calculated as follows: CHSI =[ sigma(0-t) hb-fc(0) x t] x l0(-3) x [ integral (0-t) Tre x dt-Tre(0) x t] (units) Where: hb=heart beats, fc(0)=initial lowest heart rate (bpm), Tre = rectal temperature (Tre(0) = baseline Tre) (degrees C) and t = time (min) from the onset of measurements. Four sets of data, from various former studies, have been used to demonstrate the index's applicability and its sensitivity to differentiate between levels of stain under various stressful conditions (e.g. clothing insulation, acclimation to heat and levels of tolerance to heat). In all cases, the index was found to be a sensitive tool for assessing the level of strain. Furthermore, the CHSI can be used to predict potential strain. The index's high sensitivity arises from its nature, which reflects miniature differences in the pattern of changes in the dynamics of physiological responses and therefore is a powerful and practical tool for evaluating even minor changes in strain.

Exertional heat stroke--the prevention of a medical emergency

In most cases, exertional heat stroke (EHS) can be prevented in the military setting. The actions taken by the Israel Defense Forces (IDF) and their outcome prove this well. Unfortunately, despite the available information, there are still incidents of failure of command in conducting physical exercise, leading to EHS. In our experience, most incidences are a consequence of disregarding safety regulations. The application of simple and reasonable measures will not only prevent accidents from happening, but will also result in better trained soldiers.

[Prediction of physiological response from mathematical models]

The ability to predict the physiological responses of workers exposed to extreme environmental conditions, has been a challenge to environmental physiologists for more than 3 decades. Therefore, mathematical models have been developed to predict metabolic rate under various levels of work intensity and dynamic changes in body temperature and heart rate. Based on the effect of exercise on the cardiovascular system, a model was developed to predict mean arterial blood pressure as a function of heart rate. Physiological strain could also be estimated on the basis of thermoregulatory and cardiovascular strains. This paper summarizes knowledge accumulated during 25 years of studies in the field of mathematical modeling of physiological parameters. Besides analyzing the logic underlying each model, it explains the scientific approach in developing a model from its early concept to the model's application in the field.

[Man in a hot climate--early studies of the Institute of Military Physiology]

In the 1950's many IDF soldiers were hospitalized for heat stroke--about 25% of whom died. Analyzing these cases revealed that commanders misinterpreted human ability to perform in the heat and ignored basic concepts of fluid and electrolyte balance and heat load. In the early 1960's a series of studies was conducted with regard to soldiers' performance in the heat. The first study (1959), which later became a classic, was conducted during a 21-day march from Eilat to Metula, crossing all climatic zones of Israel. The study was followed by other investigations which approached the issues of voluntary dehydration, fluid consumption vs sweat loss, salt additives, and the effect of heat load on performance. Based on these early studies, proper regulations were issued to field officers. Over the years, the lessons learned from these studies saved many lives. The number of cases of heat stroke and of other climate-related injuries was dramatically reduced, and performance was enhanced.

[Physiological aspects of women in combat]

Since military service is physically demanding, soldiers must maintain high levels of physical fitness for optimal performance of their duties. Women are at a physiological disadvantage when competing against men: they have a smaller muscle mass, more body fat, lower red blood cell counts, lower hemoglobin levels and smaller cardiac outputs. Women are slower and weaker than men and more prone to exercise-induced skeletal injuries. Fewer women than men meet the standards of physically demanding jobs. Therefore integrating women into physically demanding military-oriented jobs requires redesigning or modifying the tasks (different pace, mechanical aids, teamwork). While physical training can increase the physical capacity of women, training cannot completely eliminate gender differences. Thus the data presented do not imply that women cannot be integrated into combat units, but highlight gender-related differences which might have an effect on the ability of women to compete equally with men at the same task.

Can gender differences during exercise-heat stress be assessed by the physiological strain index?

A physiological strain index (PSI) based on rectal temperature (Tre) and heart rate (HR) was recently suggested to evaluate exercise-heat stress. The purpose of this study was to evaluate PSI for gender differences under various combinations of exercise intensity and climate. Two groups of eight men each were formed according to maximal rate of O2 consumption (VO2 max). The first group of men (M) was matched to a group of nine women (W) with similar (P > 0.001) VO2 max (46.1 +/- 2.0 and 43.6 +/- 2.9 ml. kg-1. min-1, respectively). The second group of men (MF) was significantly (P < 0. 001) more fit than M or W with VO2 max of 59.1 +/- 1.8 ml. kg-1. min-1. Subjects completed a matrix of nine experimental combinations consisting of three different exercise intensities for 60 min [low, moderate, and high (300, 500, and 650 W, respectively)] each at three climates (comfortable, hot wet, and hot dry [20 degrees C 50% relative humidity (RH), 35 degrees C 70% RH, and 40 degrees C 35% RH, respectively]). No significant differences (P > 0.05) were found between matched genders (M and W) at the same exposure for sweat rate, relative VO2 max (%VO2 max), and PSI. However, MF had significantly (P < 0.05) lower strain than M and W as reflected by %VO2 max and PSI. In summary, PSI applicability was extended for exercise-heat stress and gender. This index continues to show potential for wide acceptance and application.

Exertional heat stroke: a case series

Exertional heat stroke (EHS) is a state of extreme hyperthermia that occurs when excess heat that is generated by muscular exercise exceeds the body's ability to dissipate it at the same rate. EHS is thought to coincide with previously healthy, highly motivated, and relatively untrained individuals exerting in hot environments for long periods.

PURPOSE

To establish this notion, the present study was aimed to follow the trends in the incidence of EHS in the period 1988-1996.

METHODS

During these years, 150 cases of male soldiers (age = 20+/-3 yr) were reported to our institute as suffering from heat illnesses. According to the files, 82 cases were definitely diagnosed as EHS.

RESULTS

More than 50% of the cases occurred during the first 6 months in service. Most of the cases occurred during the summer season (June-September), but 30% of the cases occurred during the spring. EHS was not related to time in the day. Many cases occurred during the night or early morning, even under mild heat load. Forty percent of the cases occurred during very short activities, and about 60% occurred already during the first 2 h of exercise. The results were discussed in view of the regulations which prevail in the Israeli army.

CONCLUSIONS

It seems that almost all EHS cases occurred when regulations were not strictly followed.

How significant is magnesium in thermoregulation?

Nine apparently healthy male subjects, mean age 22.8 yr, SD 4.1, free from disease, medication or addiction who gave informed consent, underwent acclimation process in a heat chamber; exposed during 2 h daily for 10 consecutive days to a temperature of 40 degrees C and 40% relative humidity while walking on a treadmill elevated by 3 degrees at a speed of 5 km/h (VO2 1.2 1.min-1). Serum, mononuclear and erythrocyte magnesium (S-Mg, M-Mg and E-Mg, respectively) were monitored on day 1, 5 and 10 before and after the heat exposure. S-Mg decreased while M-Mg increased after the heat exposures, suggesting a shift of S-Mg to mononuclear cells. The decrease of S-Mg was sustained at the end of the acclimation process. E-Mg increased up to day 5 and decreased gradually approximating the baseline by day 10. Mg appears to play a significant role in heat acclimation.

Acclimatization strategies--preparing for exercise in the heat

More than 200 years ago, in 1768, Lind in his monograph: "An assay on diseases incidental to Europeans in hot climate" pointed out that habituation to hot climates reduced the danger to health. Two centuries later, Lind and Bass in a classical study which was carried out under hot/dry climatic conditions (49 degrees C and 20% rh) demonstrated that the adaptation to heat may be described as the series of physiological adjustments that occur when a person who is accustomed of living in a cool environment is transferred to a hot climate. This adaptation is a process which is fully achieved after 10 to 14 days of exposure to heat, but two thirds or even 75% of the adaptation is obtained already within 5 days (1). According to this study improved tolerance to heat is related to typical physiological changes: heightened sweating response, lowered heart rate, and lowered rectal temperature during exercise in the heat.

Heat intolerance induced by antidepressants

A case in which prescription medications induced heat intolerance which led to heat stroke is presented. A subject who suffered from depression and was treated with fluoxetine HCL (prozac) and lithium carbonate was engaged in mild intermittent work for 4 hours under hot/dry climatic conditions (Ta = 37 degrees C, rh = 15%). The subject lost consciousness, was hyperthermic and suffered from disseminated intravascular coagulation. A year later residual cerebellar symptoms were still evident and severe atrophy of the cerebellar tissue was demonstrated in a CT scan. It is suggested that drug-induced heat intolerance was the predisposing factor that reduced the patient ability to sustain exercise-heat stress, and under the favorable environmental circumstances led to excessive heat accumulation which ultimately caused heat stroke. This is the first description, to our knowledge, of heat intolerance of a patient treated by a combination of fluoxetine and lithium carbonate.

Heat acclimation: cardiovascular response to hot/dry and hot/wet heat loads in rats

Body temperature, blood pressure (BP) and heart rate (HR) of rats before and after acclimation to heat were studied in chronically cannulated sedentary conscious rats in different hot environmental conditions [hot/dry: 40 degrees C, 20% relative humidity (RH) and hot/wet: 35 degrees C, 70% RH]. During exposure to heat stress, acclimated rats showed an attenuated increase in colonic temperature (Tc) compared to non-acclimated rats. Concomitantly, an abrupt decrease in HR, delayed and attenuated elevation in mean arterial BP and improved cardiac efficiency were recorded. Differences were observed upon exposure to the hot/wet and hot/dry climates: the hot/dry climate imposed a greater physiological burden than the hot/wet climate. The data suggest that for sedentary rats dry heat produces a greater load than humid heat. Thus, the conventional heat load indices do not apply universally but have a thermoregulatory pattern specificity.

Calculation of mean arterial pressure during exercise as a function of heart rate

Mean arterial blood pressure (MAP) is a common characteristic of the cardiac cycle. Usually it is evaluated by assuming that the left ventricular ejection time (systole) constitutes a constant proportion of the cardiac cycle (i.e. 1/3), regardless of the heart rate (HR). However, elevation of HR during exercise results in a reduction of the duration of the ejection period and even a greater reduction of the ventricular filling period. Therefore, a constant diastole/systole proportion at various heart rates may be misleading. The purpose of this study was therefore to evaluate the accurate proportion of the systolic period from the cardiac cycle at different metabolic rates and calculate MAP accordingly. Twenty healthy subjects (age: 20-50 yr.) exercised at different work intensities on a cycle ergometer to elicit HR in the range of 55-180 bpm. During the ride the mitral and aortic flow velocity wave form were recorded by Doppler echocardiography; the mitral flow from the apical view and the aortic flow from the apical long axis view. Blood pressure was measured using a sphygmomanometer. The fraction of systole (St) from the heart cycle was related to HR and was described in mathematical terms as: St = 0.01exp(4.14-40.74/HR) MAP was then calculated from the diastolic blood pressure (dBP) and the pulse pressure (PP) adjusted for St as follows: MAP = dBP+St.PP; (mmHg) The use of the suggested model reduces errors in the evaluation of various cardiac parameters which are related to arterial pressure, such as peripheral resistance, especially under exercise-heat stress.

Glucose utilization in morbidly obese subjects before and after weight loss by gastric bypass operation

OBJECTIVE

To investigate the effect of weight reduction induced by gastric bypass operation (GBO), on the peripheral resistance to insulin in extremely obese subjects.

DESIGN

A three-stage euglycemic clamp was applied to assess the metabolic clearance rate of glucose (g-MCR) in lean controls and in obese subjects, prior to and 6-12 months post operation.

SUBJECTS

Six obese subjects (four obese normoglycemics-ON and two obese non-insulin dependent diabetics-OD) before and after GBO and six healthy, lean controls (LC) were compared.

MAIN OUTCOME MEASURES

Body mass index after GBO, metabolic clearance rate of glucose under increasing insulin concentrations.

RESULTS

GBO resulted in a significant change in body mass index from a pre-operation value (mean +/- s.d.) of 45.0 +/- 8.5 to 30.4 +/- 5.9 kg m-2 and remained significantly greater than controls (23.3 +/- 2.3 kg m-2). Glucose MCR increased from a mean baseline value of 3.0 +/- 1.6 to 6.7 +/- 3.9 ml kg-1 min-1 at post GBO (P) (P < 0.02). Similar effects were obtained under the two higher insulin concentration.

CONCLUSIONS

GBO resulted in a massive reduction in BMI, that still remained above normal controls. This could explain the effect of weight reduction to decrease, but not completely reverse, peripheral resistance to insulin associated with obesity.

Exertional heatstroke: a preventable condition

Exertional heatstroke is a syndrome occurring in the young and active population when homeostatic thermoregulatory mechanisms are unable to meet the demands of heat stress. In most cases its occurrence is sporadic and it is regarded as an extreme medical emergency that might result in death if not immediately diagnosed and properly treated. Following some simple regulations and providing proper instructions have proven efficient in preventing this serious disease.

Validation and adjustment of the mathematical prediction model for human sweat rate responses to outdoor environmental conditions

Under outdoor conditions this model was over estimating sweat loss response in shaded (low solar radiation) environments, and underestimating the response when solar radiation was high (open field areas). The present study was conducted in order to adjust the model to be applicable under outdoor environmental conditions. Four groups of fit acclimated subjects participated in the study. They were exposed to three climatic conditions (30 degrees, 65% rh; 31 degrees C, 40% rh; and 40 degrees C, 20% rh) and three levels of metabolic rate (100, 300 and 450 W) in shaded and sunny areas while wearing shorts, cotton fatigues (BDUs) or protective garments. The original predictive equation for sweat loss was adjusted for the outdoor conditions by evaluating separately the radiative heat exchange, short-wave absorption in the body and long-wave emission from the body to the atmosphere and integrating them in the required evaporation component (Ereq) of the model, as follows: Hr = 1.5SL0.6/I(T) (watt) H1 = 0.047Me.th/I(T) (watt), where SL is solar radiation (W.m-2), Me.th is the Stephan Boltzman constant, and I(T) is the effective clothing insulation coefficient. This adjustment revealed a high correlation between the measured and expected values of sweat loss (r = 0.99, p < 0.0001).

Validation and adjustment of the mathematical prediction model for human rectal temperature responses to outdoor environmental conditions

Models to predict rectal temperature (Tre) have been based on indoor laboratory studies. The present study was conducted to validate and adjust a previously suggested model for outdoor environmental conditions. Four groups of young male volunteers were exposed to three different climatic conditions (30 degrees C, 65% rh; 31 degrees C, 41% rh; 40 degrees C, 20% rh). They were tested both in shaded and open field areas (radiation: 80 and 900 W.m-2, respectively) at different work loads (100, 300 and 450 watt). Exercise consisted of two bouts of 10 minutes rest and 50 minutes walking on a treadmill, at a constant speed (1.4 m.s-1) and different grades. The subjects were tested wearing cotton fatigues and protective garments. Their Tre and heart rate were monitored every 5 min and skin temperature every 15 min, oxygen uptake was measured towards the end of each bout of exercise; concomitantly, ambient temperature, relative humidity and solar load were monitored. We concluded that: (a) the corrected model to predict rectal temperature overestimates the actual measurements when applied outdoors; (b) radiative and convective heat exchanges should be considered separately when using the model outdoors; (c) radiative heat exchange should also be considered separately for short-wave radiation (solar radiation) and long-wave emission from the body to the atmosphere. Finally, an adjusted model to be used outdoors was suggested.

Predicting heart rate response to various metabolic rates, environments, and clothing

A mathematical model that describes heart rate (HR) responses to different combinations of metabolic levels, climatic conditions, and clothing ensembles was developed. The database that served to construct the model consisted of 48 variations representing a wide range of environmental conditions, clothing ensembles, and metabolic rates. The model, which correlates highly with the observed values (r = 0.88, P < 0.0001), is based on physiological and environmental parameters: HR = 57.1 + 0.6HRi + [0.07M - 19.06 - 0.011(Emax - Ereq)] log t, where HRi is initial HR in beats per minute (at rest before the exposure), t is the time of exposure in minutes, M is the metabolic rate in watts, Ereq is the required sweat evaporation for thermal equilibrium in watts, and Emax is the maximal evaporative capacity of the environment in watts. The model's validity was tested by using two independent databases representing wide ranges of conditions; the correlation between measured and predicted values was found to be highly significant (r = 0.83, P < 0.001 and r = 0.77, P < 0.001, respectively). In summary, the present study suggests a valid predictive model for HR that overcomes some of the difficulties observed in other models.

Behavioral evidence for the existence of two pools of cellular inositol

Lithium reduces brain inositol levels by inhibiting inositol monophosphatase. In a previous study it was found that administration of pilocarpine to Li-treated rats causes limbic seizure behavior which can be reversed by i.c.v. myo-inositol but not chiro-inositol, suggesting that this behavior is related to inositol depletion in the PI cycle. Hyponatremia can lower brain inositol and hypernatremia can raise brain inositol. We now report that induction of low brain inositol by hyponatremia followed by pilocarpine did not cause limbic seizures. Induction of high brain inositol using hypernatremia followed by Li-pilocarpine administration did not reverse limbic seizures. These data support the concept that inositol available for P1 synthesis and inositol for osmotic function are sequestered in different cellular pools.

High-dose peripheral inositol raises brain inositol levels and reverses behavioral effects of inositol depletion by lithium

Lithium (Li) reduces brain inositol levels. Berridge has suggested that this effect is related to Li's mechanism of action. It had previously been shown that pilocarpine causes a limbic seizure syndrome in lithium treated rats, and that these lithium-pilocarpine seizures are reversible by intracerebroventricular inositol administration to rats. We now show that although inositol passes the blood-brain barrier poorly, large doses of intraperitoneal (IP) inositol can also reverse Li-pilocarpine seizures. Using gas chromatography, IP inositol can raise brain inositol levels. Demonstration that inositol enters brain after peripheral administration provides a basis for possible pharmacological intervention in psychiatric disorders at the level of second messengers linked to the phosphatidylinositol cycle.

The effects of the modified intermittent sequential pneumatic device (MISPD) on exercise performance following an exhaustive exercise bout

The Lymphapress, a pneumatic sequential intermittent device is recognized as one of the most effective conservative treatments for lymphoedema, due to its effective 'milking mechanism'. This led us to hypothesize that accelerated removal of fatigue-causing metabolites by mechanical massage could improve an athlete's performance capacity. We conducted trials with 11 men who exercised at a constant workload, on a cycle ergometer, until exhaustion. During a 20-min recovery period a new modified pneumatic sequential intermittent device (the MISPD) was applied to the subjects' legs. The men then performed a second constant load exercise bout. Cardiorespiratory parameters were measured during exercise and blood was withdrawn during recovery for the determination of lactate, pyruvate, ammonia, bicarbonate and pH. No difference was found in the blood levels of the 'fatigue causing metabolites' during passive recovery (PR) and recovery with the MISPD (MR). However, the MISPD effected a 45% improvement in the subjects' ability to perform the subsequent exercise bout. The accumulation of fluid in the interstitial space after exercise and its disappearance after the use of the MISPD offers one possible explanation for these results, although psychological effects cannot be discounted.

Seasonal changes in red blood cell parameters

Seasonal changes in blood count (haematocrit and haemoglobin values) have been described in studies of small samples. Since Israel is characterized by high summer temperatures, we attempted to determine whether there are circannual changes in blood count, and how they are influenced by mean monthly temperature. In a cross-sectional study, venous blood was drawn from 4317 male employees in industry aged 20-64 years. Blood count values were analysed by month. To estimate possible changes in serum osmolality, serum electrolytes were also examined. Values of haemoglobin and haematocrit in August were significantly lower than during the rest of the year. Circannual rhythms explained between 10% and 57% of the variances of all the variables as assessed by cosinor rhythmometry, although they had wide confidence intervals and most were not statistically significant. The lower mean haematocrit in August reflected reduction in mean corpuscular volume (MCV) rather than a decrease in red blood cell count (RBC). The change observed in haematocrit and haemoglobin in August is possibly related to heat acclimatization rather than to endogenous sinusoidal circannual rhythms. Both plasma and red cell volume expansion appear to occur. Possible seasonal changes should be taken into account in evaluation of blood counts.

Glucose uptake by adipocytes of obese rats: effect of one bout of acute exercise

The effect of one bout of acute exercise on impaired glucose metabolism was studied in obese (480 +/- 20 g), untrained rats, at rest (n = 10) and after 60 min of swimming (n = 5). Using the euglycemic, hyperinsulinemic (10 mU.kg-1 x min-1) clamp, glucose clearance rate increased from 7.6 +/- 0.9 at rest to 9.7 +/- 0.5 mL.kg-1 x min-1 after exercise (p < 0.05). Glucose (3-O-[14C]methylglucose) transport (GT) into epididymal adipocytes were incubated with or without insulin. In the absence of insulin, GT was 0.13 +/- 0.02 and 0.26 +/- 0.07 fmol.cell-1 x min-1 at rest and after exercise, respectively. In the presence of insulin (25-1000 microU.mL-1) GT increased at rest from 0.97 +/- 0.08 to 1.13 +/- 0.07 fmol.cell-1 x min-1, and after exercise from 1.35 +/- 0.05 to 1.87 +/- 0.11 fmol.cell-1 x min-1. GT was significantly higher after exercise compared with rest (p < 0.004). At rest, maximal insulin effect was achieved at 100 microU.mL-1, whereas with exercise, GT increased gradually with the insulin dosage. The following may be concluded: (i) the biological effect of insulin is amplified in obese rats by one bout of exercise and (ii) exercise affects GT into enlarged adipocytes by enhancing tissue responsiveness to insulin and by a cellular mechanism unrelated to the insulin action.

[Glucose polymer solutions and prolonged exertion in the heat]

The effect of glucose polymer solutions on physical performance has been extensively investigated, mainly under controlled laboratory conditions. The influence of such beverages on fluid balance and on glycemic state in the field, during prolonged exercise of moderate intensity (a 134 km march) in the heat (32-41 degrees C, 60-14% relative humidity) was therefore studied. 48 endurance-trained men were randomly assigned to drink either a 7.2% glucose polymer (GP) electrolyte beverage or tap water (TW); there were 24 in each group. Each group was then divided into subgroups that either consumed fluid ad libitum, or were instructed to consume 1000 ml/hr. Mean fluid consumption of all subgroups was similar. There was a greater change in plasma volume for the TW than for the GP group (+7.9% vs. +4.8%, respectively; p less than 0.05). However, in neither the GP nor the TP group did dehydration exceed 2% of body weight. Blood glucose concentration increased significantly in subjects ingesting GP (p less than 0.01) while it decreased on each day of march in those drinking TW. It is concluded that the fluid intake recommended at present by the IDF is adequate to maintain hydration within the normal range during physical effort in the heat. The differences between the GP and the TW groups in this study do not justify the substitution of glucose-polymer solutions for water during prolonged, moderate exercise.

Community coordination and information centers during the Persian Gulf war

During a time of crisis, community information centers provide valuable data to the public and help to avoid confusion and misinformation. During the Persian Gulf war, Kupat Holim (sick fund of the General Federation of Labor) established a national casualty information center in Tel Aviv as well as numerous coordination and information centers throughout the country, which included district, geriatric, psychological and emergency centers, as well as one for new immigrants. These centers had not been planned in advance, but because of the obvious need, they were established in the few months prior to the outbreak of the war and during the war itself. The locations of the centers were publicized through the media. In this article we report on the different centers and their activities, and additional community measures are described. The plan of establishing information centers throughout the country proved itself a vital necessity and will be incorporated in future Kupat Holim plans for war or any other emergency situation.

Medical aspects of the Iraqi missile attacks on Israel

During the period 18 January-28 February 1991, a total of 39 Iraqi modified Scud missiles landed in Israel, most of them in the densely populated Tel Aviv area. There were 23 missile attack alerts. These attacks caused 1,059 cases of injury; there were two deaths and 232 patients were admitted to emergency rooms for injuries directly related to the explosions, only one of which was severe. A survey among 91 of the injured showed that 46.6% of the wounds were caused by glass splinters, 31.1% were blunt contusions, and 22.2% were acute psychological reactions. No case of blast injury was reported. Inappropriate injection of atropine was reported in 230 cases. Acute anxiety was the reason for admission of 544 patients to emergency rooms. Another 40 patients sustained various traumas while rushing to the sealed room. The relatively low number of injured people is striking in view of the density of population in the areas hit. Various explanations are discussed.

Are psoriatic patients at risk of heat intolerance?

Sixteen young male subjects with psoriasis (mean of 4.9% of skin surface area involvement) and 10 healthy controls underwent a heat exercise test (40 degrees C, 40% r.h.) for 2 h. Rectal temperature (Tr), mean skin temperature (Tsk), heart rate (HR) and heat storage (dS) were measured and calculated. A sharper rise was found for all parameters in the psoriatic patients as compared with controls. Statistically significant differences were found in Tr after 60 min (37.9 +/- 0.1 degrees C and 37.5 +/- 0.1 degrees C in patients and controls, respectively) and at termination of the exercise (38.3 +/- 0.1 degrees C and 37.5 +/- 0.1 degrees C). Heat storage at the end of the first hour was 78 +/- 9 and 30 +/- 7 kcal in patients and controls, respectively. At the end of 120 min, heat storage in the study group increased to 87 +/- 14 kcal, while the control group stored only 30 +/- 7 kcal. Sweat rate was lower in the psoriatic patients (590 +/- 49 g/h) than in controls (691 +/- 42 g/h), even when corrected for healthy skin area (337 +/- 26 g/h/m2 compared with 370 +/- 24 g/h/m2). It is suggested that psoriatic patients have a reduced ability to dissipate extra heat during exposure to exercise in the heat. Psoriasis should therefore be considered as a risk factor for heat intolerance.

The effects of glucose polymer beverage ingestion during prolonged outdoor exercise in the heat

The aim of this study was to examine the effect of ingestion of a glucose polymer drink on fluid and metabolic balance during a 30 km outdoor march in the heat (ambient temperature, 26-31 degrees C; relative humidity, 53-34%). The subjects were randomly assigned to one of three groups: 7.2% glucose polymer-electrolyte beverage (GP) (N = 16), flavored sweetened placebo drink (SP) (N = 15), and tap water (TW) (N = 18). The subjects in the three groups consumed similar volumes of fluid, and no differences were found in sweat rate and percent dehydration. Changes in plasma volume were smaller, though not statistically significant, for GP than for SP and TW (-2.8%, -5.4%, -9.4%, respectively). Changes in sodium concentrations and serum osmolality were similar in the three groups. Subjects consuming GP maintained during exercise a significantly higher (P less than 0.001) blood glucose concentration (range: 6.5-7.4 mmol.l-1) than the SP and TW groups. They were also found to have increased levels of serum insulin (29.3 +/- 18.5 mU.l-1) and no change in serum free fatty acids (0.52 +/- 0.19 mmol.l-1). In contrast, subjects ingesting SP or TW had significantly elevated (P less than 0.001) concentrations of free fatty acids (range: 1.35-1.74 mmol.l-1) compared with subjects consuming GP (0.35-0.52 mmol.l-1), with no significant change in blood glucose and serum insulin levels over the exercise period. We conclude that highly trained endurance athletes may maintain a higher blood glucose level by consuming GP during prolonged exercise in the heat without impairing fluid replacement.

Long term effects of peak strenuous effort on serum magnesium, lipids, and blood sugar in apparently healthy young men

Earlier findings showed a sustained lowering of serum magnesium concentration (S-Mg) which indicated the presence of Mg deficit, and a parallel, delayed rise of blood sugar and serum lipids as a sequel to strenuous effort. S-Mg was still significantly decreased 3 months after termination of peak effort. To gain further perspective, we followed the biochemical sequels of exertion over an extended period of observation, while maintaining the same experimental conditions used earlier, which mimicked those employed in the training of military recruits. We examined two groups of military recruits, n = 15 (group 1), n = 16 (group 2), mean age 18.6, SD 1.3 and 18.7, SD 0.6, years respectively, who underwent a graded training programme of 7 months' duration culminating in a 120 km forced march. Blood was sampled for estimation of S-Mg in 20 soldiers on recruitment, 6 and 10 months after the 120 km march in group 1, and 9, 11 and 15 months after the march in group 2. Blood sugar and serum lipids were screened on recruitment and up to 11 months after the 120 km march. A significant lowering of mean S-Mg was found as late as 10 months after completion of the march in group 1, and 11 months in group 2 (P less than 0.01). Mean serum cholesterol and triglycerides showed a delayed rise, especially in group 2 (P less than 0.05 and P less than 0.001, respectively), whereas blood sugar decreased in group 1, but increased in group 2 (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)