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The issues of thermal physiology, protection, modeling, survival, and injury have been addressed in thousands of publications over the decades, and the topic of thermal protection and survival has been the subject of several NATO DRG and AGARD symposia. Therefore, rather than review the current state of the art of the field which is the subject of the many papers that will be presented at this Symposium, this paper re-examines some of the pioneer work in cold physiology that has laid the foundations of our current understanding as to how humans have adapted to severe cold climates, often without modem technology or clothing. Scholander, Hammel, Elsner, Andersen, and Hart are some of the scientific pioneers that have provided evidence from field trials that a variety of physiological adaptations can develop in the human species exposed to different climatic extremes ranging from one Pole to the other Pole. From these classical field studies, several different types of cold acclimatization of native races were identified. This paper reviews how some of these acclimatizations can be or have been applied to modern man. In conclusion, it appears that a rapid technique using intermittent exposure to severe cold for inducing cold adaptation or cold habituation does exist and does induce beneficial effects in soldiers required to subsequently perform and sleep under arctic conditions. It appears to be a hypothermic type of adaptation and eliminates the negative effects of cold diuresis. Furthermore, this technique appears to persist over a significant period of time even in a temperature environment making it even more of a desirable military technique. One sees a shift of the shivering threshold to a lower temperature, a shorter period of adaptation, and an increase in cold tolerance. It appears to be more akin to the type of adaptation demonstrated by the Australian aborigine and Kalahari bushman, that is, an Insulative Acclimatization., 8 Oct 2001 to 10 Oct 2001, "The original document contains color images" Papers presented at the RTO Human Factors and Medicine Panel (HFM) Symposium held in Dresden, Germany, 8-10 Oct 2001, pKN1-1/KN1-19. This article is from ADA403853 Blowing Hot and Cold: Protecting Against Climatic Extremes (Souffler le chaud et le froid: comment se proteger contre les conditions climstiques extremes)

The purpose of the present report is to summarize the main findings of our research in the area of inner ear decompression sickness in deep diving environments. From these observations, a plausible theory has been developed which explains many of the results that were obtained. Furthermore, interpretation of the results suggests what procedures constitute acceptable therapeutic treatment for the successful management of inner ear decompression sickness.

Presented at the Annual Meeting (5oth) of the Aerospace Medical Association, May 79.

Plasma and urinary levels of lactic acid were measured in rats exposed to simulated altitudes of 18,000, 24,000 and 26,000 ft for six hr periods. Acute exposure (six hr) to 18,000 ft. did not alter the basal level of lactic acid excretion but 5-fold and 50-fold increases were found in animals after six hr at 24,000 and 26,000 ft, respectively. A large interindividual variability in lactic acid excretion was observed at 24,000 and 26,000 ft with values ranging from 4 to 1,000mg/25mg urinary creatinine. Injection of adrenalin increased urinary lactate levels at altitude whereas prior fasting eliminated altitude-induced increases in lactic acid. It is suggested that at altitude, lactic acid formation from liver glycogen is, in part, mediated by increased adrenalin secretion and that when blood lactate exceeds a critical level (14 - 19mg percent), lactic acid increases in the urine. (Modified author abstract)

The two components of lipovitellin and the three major components of yolk granules, phosvitin, alpha and beta-lipovitellin, were separated by gradient elution chromatography on TEAE-cellulose. A 0.2 M phosphate buffer (pH 6.8) had the necessary ionic strength to dissolve these proteins and when applied in this solvent all components except beta-lipovitellin were retained by the column. A linear gradient of ionic strength (limit buffer 0.2 M phosphate plus 0.5 M NaCl) was used to remove the other components. Recovery was essentially complete and the composition and properties of the individual components were similar to those obtained by previous chromatographic methods that gave only partial recovery.

Lithium, which has been used in the treatment of certain hyperexcitable states in humans, was tested at various doses and pretreatment times for its effectiveness against the convulsions and lung damage induced by hypervaric oxygen (OHP) (5.5 ata). Changes in brain gamma-aminobutyric acid (GABA) prior to the onset of OHP convulsions were also monitored. Lithium at 9.4 mmol/kg proved to be highly effective in inhibiting the development of OHP-induced convulsions and lung edema in rats. Lithium also prevented the decrease in brain GABA which invariably precedes convulsions in control animals. Protection was evident only at peak serum levels of lithium (15-60 min postinjection) but was absent 24 hr postinjection at which time brain levels of lithium were maximal. The evidence suggests that the anti-convulsive property of lithium in the animal exposed to OHP is related to its effects on central neuroinhibitory processes and on brain GABA metabolism. (Modified author abstract)

A linear correlation was obtained between the relative rate of y-aminobutyric acid (GABA) metabolism in chicks of different ages during a period of rapid brain development and the susceptibility of the birds to seizures induced by hyperbaric oxygen (O.H.P.). Since the changes taking place with age in the activities of the two enzymes involved in GABA metabolism (glutamic acid decarboxylase and GABA-alpha-ketoglutarate transaminase) were similar, the enzyme system primarily responsible for the O.H.P.-induced decreases in cerebral GABA levels and accompanying seizures could not be identified. Both enzyme systems may be involved. The possible involvement of an increased transport of GABA through cellular memebranes in the production of low cerebral GABA levels could not be demonstrated in the present experiments. (Author), Prepared in Cooperation with Saskatchewan Univ; Saskatoon. Dept. of Biochemistry.

The effect of the parenteral administration of various metal ions on the su ceptibility of rats to the toxic effects of oxygen at high pressures (OHP, 75 psig) has been studied. The incidence of seizures and degree of lung damage in the treated animals were monitored. Cobalt, potassium, and calcium were without effect on oxygen toxicity in the rat. Magnesium (0.5-2.0 mmoles/kg) strongly protected rats against OHP-seizures with zinc and manganese showing marginal protection. The anticonvulsant effect of magnesium was eliminated by simultaneous injection of calcium. The development of lung edema in the exposed animals was prevented by certain doses of manganese and zinc while magnesium had no effect on this syndrome. Although no cation tested was equally effective against both syndromes of oxygen toxicity, a mixed ion treatment of magnesium and manganese alleviated both convulsions and lung damage, (Author), Prepared in cooperation with Saskatechwan Univ., Saskatoon, Dept. of Biology.

The correlation observed in these experiments between the retention of the extracellular cations, sodium and calcium, and the partial pressure of nitrogen implicates the narcotic properties of nitrogen in these changes. This view is strengthened by the lack of any effect with helium, which is non-narcotic at similar partial pressures. Furthermore, the reversibility of these electrolyte changes upon decompression is in accord with the reversible nature of nitrogen narcosis. Similar changes in electrolyte excretion have been reported during general anaesthesia and alcohol inebriation (Papper and Ngai, 1956). The electrolyte retention observed may be a homeostatic adjustment by the body to compensate for the type of electrolyte imbalance that has been reported to occur with inert gas narcosis (Bennett and Hayward, 1967). (Author)

Experiments on an isolated canal in the living animal have shown that blocking of the vascular supply results in a decrease in endolymph potassium concentration in this canal. In three hours of vascular blockade, the concentration falls to that of the surrounding perilymph. If the isolated canal has been filled with artificial perilymph and its vascular supply intact, the potassium concentration increases, indicating a selective ion-transport function of the canal epithelium which, under normal conditions, might contribute to maintaining the high potassium concentration of the endolymph in the canals as well as in the rest of the membranous labyrinth. (Author)

The effect of cold exposure and choline deficiency on the levels of liver lipids of male albino rats was studied at four dietary intakes of methionine (20-100 mg per rat per day). After exposure of the animals to cold (2-3 degrees C) for a 10-day period, the liver lipids were analyzed for total and free cholesterol, phospholipid, and triglyceride. In choline-fed animals, cold exposure did not affect triglyceride or total cholesterol levels but elevated phospholipid and free cholesterol and decreased ester cholesterol. The increase in phospholipid levels occurred at all methionine intakes with the changes in the cholesterol fractions occurring only at methionine intakes >40 mg per day. In choline-deficient rats, there was evidence that the lipotropic action of cold exposure was related to dietary methionine intake. At methionine intakes <60 mg per rat per day, fatty infiltration of the livers of the choline-deficient cold-exposed rats occurred, as evidenced by the accumulation of triglyceride and ester cholesterol. Concomitantly, phospholipid levels decreased. The data suggest that cold increases the capacity of the animal to synthesize choline from endogenous sources. (Author), Pub. in Canadian Journal of Physiology and Pharmacology v42 p769-77 1964 (Copies available only to DDC users).

The ADP/O ratios of single-sedimented liver mitochondria from heat-acclimated Sprague-Dawley rats were greater than control and cold-acclimated ratios (heat>control>cold). These differences were abolished by washing the mitochondria. EDTA in the homogenate reduced to a greater extent the magnesium and calcium content in mitochondria of cold- than heat-acclimated preparations. Elevation of magnesium in the medium increased ADP/O values and reduced respiratory rates in all mitochondrial populations. During calcium respiration ADP/O ratios were decreased significantly in cold-acclimated mitochondria. (Author)