The exchange rates of radioactive magnesium in various tissues of the rat were compared in normal and hypothermic animals ( 20° C}. The temperature effect was similar to that measured in isolated rat muscles incubated at 37° and 20° C, and the Q10 was 1. 7 in each case. Frog muscles were incubated at various temperatures, and the Q10 of Mg28 influx was calculated to be 1. 8; the Q10 of the concurrent efflux was 1. 2. These data suggest that the magnesium concentration in the cells is maintained by an active transport mechanism, and that the rise in serum magnesium in hypothermia is in part due to inhibition of this transport mechanism. The exchange rates of radioactive magnesium are less in the tissues of cold adapted rats than in normal controls, and the difference applies principally to the more rapid components of the exchange. Magnesium uptake by the rat liver is increased by administration of glucose and insulin, but this is evidently not a stoichiometric relationship between liver magnesium and liver glycogen.
A study was carried out to establish whether or not rats could be regularly carried to deep hypothermia and then rewarmed without an excessively high mortality rate. A technique for inducing deep hypothermia is described. Rats were cooled to deep hypothermia and revived in a high enough percentage to permit quantitative estimates of other experimental situations. Hypoxia during cooling and warming is apparently important in the improvement of mortality figures. Circulatory arrest of 60 minutes or less is well tolerated during deep hypothermia.
Human cold adaptation was studied by comparing maximal body insulations (I values) of Korean diving women, non-diving women and men,, and of American men and women. The diving women had significantly larger I values than Korean men, due to thicker subcutaneous fat. There was no difference in I value or subcutaneous fat thickness between the diving women and the non-diving women. The Koreans had 30 per cent higher I values than Americans of comparable subcutaneous fat thickness, signifying greater vasoconstriction and a thicker shell of non-perfused tissue. The "critical water temperature" at which shivering occurred was 30° C or lower for the diving women. For other subjects of comparable fat thickness it was 31° to 34° C. This elevated shivering threshold of the diving women was the only evidence of acquired cold adaptation. The thicker subcutaneous fat of women offers more protection to cold and may be the reason why women and not men engage in diving.
Radioautography of peripheral blood subsequent to Fe59 administration was employed to determine the rate of erythrocyte formation in male Sprague-Dawley rats maintained at 24° C and after exposure to 5° C for 4, 5, and 6 weeks. The rate at which newly-formed labeled cells appeared in the blood was approximately 3 per cent per day of the total circulating erythrocyte population for both control and experimental animals. This rate was the same for animals of two body weight ranges, 150 to 200 grams and 300 to 400 grams. Assuming that the rate of new red cell formation is equal to the rate of red cell destruction, the circulating life span of the rat erythrocytes is estimated to be approximately 33 days.
The effect of induced hypoxia on body temperature regulation and cardiopulmonary function is assessed in anesthetized dogs under warm, neutral and cold environments. Hypoxia acts differently to heat conservation (shivering) and heat dissipation (thermal panting) mechanisms: the former is suppressed, while the latter is facilitated. It is also found that the suppression of shivering is partly due to the hypocapnia which is produced under hypoxia. The lethal threshold of acutely induced hypoxia is at the inspiratory O2 level of approximately 3 per cent in the neutral and cold environments, whereas it is at 5 per cent in the warm environment. Under hypoxia, the total ventilation is increased two- to threefold. The alveolar ventilation, however, is augmented to a lesser degree with a progressive increase in physiological dead space. Contrary to respiration, the cardiac output is only slightly increased (less than 30 per cent over the control value) under hypoxia.
Shivering and heat loss in the cold were determined in 46 cats several weeks or months after bilateral destruction of various septal and hypothalamic regions. Septal lesions had no effect on either parameter. The tremor was abolished or markedly reduced in cats with lesions in the dorsomedial region of the posterior hypothalamus, but postural, pilomotor and behavioral responses to cooling persisted. Lesions of the dorsolateral region of the posterior hypothalamus increased heat loss despite the presence of shivering, huddling and piloerection. These results confirmed our previous electrical stimulation data that the primary region controlling the efferent (motor) aspect of shivering is the dorsomedial region of the posterior hypothalamus and additionally indirectly suggested that the dorsolateral region of the posterior hypothalamus is implicated in cold-induced cutaneous vasoconstriction.
The levels of oxidized and reduced di- and triphosphopyridine nucleotide were measured in liver tissue from rats that had been exposed to cold (4° ± 1° C) for one month. These animals exhibited about 65% more TPNH and total triphosphopyridine nucleotide than control animals maintained at an ambient temperature of 25° ± 1° C. The significance of these alterations to the efficiency of oxidative phosphorylation is discussed.
A small carbon filter was investigated to determine the effectiveness of removing color from surface waters at remote Air Force radar sites in Alaska. The raw water was characterized by color ranging from 50 to 90 units, pH near 6, temperature 5° Celsius, and low turbidity. When using carbon with a particle size high enough to provide low pressure losses, the color removed was less than 50 per cent. With powdered activated carbon, pressure losses and carbon carryover caused the system to be considered unacceptable even though color removal was high.
During recent years much effort has been expended in attempting to develop principles, techniques, and instrumentation leading to the ultimate goal of utilizing photosynthetic organisms for the support of man in an extraterrestrial environment. This study was designed to determine if solar illuminated photosynthetic gas exchange systems would be feasible, and to provide sufficient data to determine if further consideration of this approach would be warranted.
Comparative growth and photosynthetic data of two species of algae under various conditions are presented. Chlorella pyrenoidosa, strain TX 71105, and the 52° C strain of Synechococcus lividus were cultured in thin films in hemispherical domes and solar oriented flat panels during the long Alaskan days of June and July 1961. Growth and photosynthetic rates were measured in cultures having film depths of 1, 2 and 4 cm under solar illumination. The maximum production rate observed in the flat panels was over 50 grams of algae and approximately I00 liters (STP) of oxygen per square meter of illuminated surface per day. Based on the observed data, it is estimated that the illuminated area of algal suspension required for a one man gas exchanger will be six square meters or less. The maximum volume of the illuminator will be 60 liters. A small additional volume must be added for pumping and for gas exchange.
This presents a critical discussion and interpretation of principles of leadership and management with particular reference to the problems of AC&W sites in Alaska. It is based on a review of scientific research in the fields of psychology, sociology and management science, primarily. The major topics covered include relations of management and leadership, group-centered vs. production- centered management, organizational relations, .organizational control, and leadership in formal organizations: Selected references are cited and reference is made to an annotated bibliography containing abstracts of significant studies: AAL Reports 61-18 to 61-24, incl.
This review is part of a bibliographic study of research on factors related to the effectiveness of Aircraft Control and Warning (AC&W) sites in Alaska. The literature surveyed has previously been summarized in a series of annotated bibliographies (Reports AAL TR 61-19 to 61-24). The critical reviews based on this literature have been prepared as a series of five reports, covering the following topics: I. Informal, Natural Groups: Development, Structure, and Function; II. Dimensions of Group Structure and Group Behavior; III. Environmental Stress and Behavior Ecology; IV. Organizational Staffing; and V. Psychological Principles of Management and Leadership. The assistance of Mr. George Haven is acknowledged in the preparation of these reviews.
A critical research review of behavioral effects of isolation, cold, and general stress, with particular reference to AC& W sites in Alaska. On the basis of the literature, environmental stress does not appear as a major threat to adjustment of troops stationed at AC& W sites. Human engineering has contributed greatly to the comfortization and control of the environment, and there appears to be a wide difference between conditions of the area and conditions of the specific work and living environment, except in cases of emergency. The possibility of such emergencies may be a threat, but few have occurred. The positive values of motivation, training 1 and group dynamics (including leadership) as factors which offset the disorganizing effects of environmental stress are pointed out.
This report covers a summary of 300 animal experiments during profound hypothermia which stresses (1) the acceptable animal survival rate, (2) the favorable metabolic state afforded by this technique and (3) the protective action of profound hypothermia against even severe oxygen deprivation. The technique of profound hypothermia induced and controlled with a pump oxygenator has been shown to be feasible by these studies and has now been widely accepted for clinical application. It has become increasingly evident that, though long periods of circulatory arrest can be achieved, flow of oxygenated blood ought not to be stopped unless the operation demands it. The basis for this statement rests upon the observations that oxygen is utilized during profound hypothermia. There are few cardiac operations where prolonged circulatory arrest is ever needed.
Human subjects were used to test the effects of two simple diets of varying fat content on thiamine excretion. plasma cholesterol, ketone excretion and the oxygen cost of exercise. After subsistence on the high fat diet (60% of Calories) for two weeks, the subjects basal excretion of thiamine and their load dose returns of urinary thiamine were significantly less than on the low fat diet (18% of Calories). This was considered to be evidence that a high fat diet ha.s a sparing effect on the thiamine requirement of humans.
In the 2-week period plasma cholesterol levels were significantly increased by subsistence on the low fat diet; no change was observed when the subjects ate the high fat diet. These effects were attributed to the predominately saturated nature of the fat in the low-fat diet, in contrast to the high fat diet in which 69% of the fat was unsaturated corn oil. No changes were observed in ketone excretion or in the oxygen cost of exercise during these experimental periods.
Cold exposure increases the secretion of catechol amines and enhances the effect of these hormones on metabolism. Whether the sensitivity of peripheral vessels to epinephrine and norepinephrine is altered by cold exposure has not been reported. Warm- adapted (27° ± 1° C) and cold-adapted (5° ± 1 ° C) rabbits were studied under chloralose and urethane anesthesia. Epinephrine and norepinephrine were infused (3 gamma/kg/min) through an ear vein. Rectal plus ear temperature, EKG, blood flow and venous pressure in the ear were measured. Compliance of veins was calculated from the ?V / ?P at pressures between 20 and 30 mm Hg.
After prolonged cold exposure rabbits responded to catechol amine infusion (adrenaline and noradrenaline) with less change in heart rate during infusion and a more rapid return to control levels following infusion; with less decrease in ear temperature during infusion and a more rapid return to control levels following infusion; less increase in peripheral resistance, and less effect on compliance of the capacitance vessels (veins).
Adult male albino rabbits challenged intratesticularly with viable Spirochaete pallida suspension and kept at 3° C .or 21° C developed syphilomata at the same rates. Adverse environmental temperatures apparently do not enhance or decrease the rabbit's resistance to the challenge. Rectal temperature measurements during the experimental period show no gross differences in animals kept at 3° C or 21° C, and the temperatures remained quite constant throughout the experiment.
Normal and immunized mice were subjected to acute and chronic stress of 2° C ambient temperature. The mice were challenged with varying doses of Staphylococcus aureus, strain Fritchie. Immunization offered significant protection to mice kept at 21° C and to mice that were immunized, challenged and acutely exposed to 2° C in groups. No protection was observed in mice that were immunized, challenged and exposed as individuals to 2° C. Also, immunized mice that were chronically cold exposed at 2° C were not protected against subsequent challenge and showed equivocal mortality ratios compared to the normal controls challenged under the same conditions.
In acute experiments on 38 lightly anesthetized cats, the septal region of the forebrain and the hypothalamus were explored for loci whose activation by electrical stimulation produced, suppressed or failed to affect shivering. Shivering was consistently and repeatedly produced by stimulation of the dorso-medial region of the posterior hypothalamus, and sometimes by stimulation of the ventrolateral region of the septum. A greater intensity of stimulus was needed to produce more latent and less intense shivering during septal than during hypothalamic stimulation. Similarly, more intense stimulation was necessary to suppress shivering during ventromedial septal stimulation than during anterior, or ventrolateral posterior hypothalamic stimulation. The most effective stimulation frequency for both activation and suppression of shivering was 50 pulses/sec, i.e. fivefold the evoked or suppressed limb tremor frequency. On the basis of these results it was concluded that septa! influences on shivering are secondary to a primary hypothalamic modulation of this tremor. Such modulation appears to be more concerned with initiation and maintenance than with the rhythm of shivering.
The effects of decerebration and decortication on the metabolic intensity of shivering in cats were determined. There was neither shivering nor an appreciable rise in the oxygen consumption rate of chronic decerebrate cats during rapid cooling. The intermittent somatomotor activity that was induced by rapid cooling was occasionally tremulous but it was also evoked by rapid warming and was absent during slow cooling and warming. This suggested that the motor activity of decerebrate cats during rapid cooling was more a generalized avoidance response to nociceptive stimulation than a temperature regulating mechanism. In decorticate cats shivering was depressed three days after surgery, the mean shivering to nonshivering ratio in oxygen consumption rate being 1.6 ± 0.12 (S. D. ), while the same ratio before operation was 2.6 ± 0.48 (S. D. ). One month after decortication shivering had returned to its pre-operative intensity. This suggested that the net telencephalic influences on shivering could hardly be suppresive, as suggested by some earlier investigators.