Abstract

Ten macaque monkeys were trained on a complex behavioral program containing both aversively and appetively rewarded tasks. A 2-phase experimental design was utilized. During Phase I all subjects were repeatedly exposed at I of 2 dose levels of monomethylhydrazine and pyridoxine HCI. The monomethylhydrazine (i.p.) and pyridoxine HC1 (i.m.) injections were administered simultaneously. Phase II was a replication without pyridoxine HCI. Data included behavior on a Sidman avoidance schedule, FR 100, and 3-stimuhs oddity for food, as well as discrete avoidance with both visual and auditory cues. Gross clinical signs were noted. Dose-response and temporal relationships were investigated. Appetitive responding was found to be most sensitive and the differences between Phase I and Phase II provide some evidence that pyridoxine HCI is effective as a therapeutic agent in situations involving exposure to low levels of monomethylhydrazine.

Abstract

The effects of some inert gases at pressures slightly less than one atmosphere on the respiration rate of rat liver slices at various partial pressures of oxygen have been studied. Contrary to some previous publications they have no detectable effect.

Abstract

The hemolytic effect of 100 percent oxygen under hyperbaric pressures has been recognized for several years. In order to elucidate the mechanism of this biologic phenomenon, mice deficient in tocopherd, a lipid antioxidant, were subjected to oxygen under high pressure, and erythrocytes were examined for alterations in fatty acid composition. The results showed that, in contrast to total saturated fatty acids which showed no change after OHP, there was significant decrease in the percent composition of total unsaturated fatty acids when compared with controls. Furthermore, the specific fatty acids involved also appear to be altered by fn vitro incubation of red cell suspensions with hydrogen peroxide vapor. These studies are the first in vfvo demonstration of alterations in fatty acid composition of red cells by hyperoxia. They suggested that peroxidation of erythrocyte lipid does occur in vivo and that this event precedes hemolysis. The relationship between hemolysis and lipid peroxidation was discussed.

Abstract

Two groups of 6 dogs each were exposed continuously for 9 days to an environment having a total barometric pressure of 260 nun. Hg, a partial pressure of 140 mm. Hg Oz, and either 60 or 90 man. Hg CO₂ Arterial samples were collected daily from a previously exteriorized carotid artery. Exposure to the 60 mm. Hg P_co2= resulted in a drop in arterial pH from 7.42 to 7.32 followed by recovery after 4/-5 days to between 7.36 and 7.39. Exposure to 90 man. Hg P_co2 resulted in a pH drop. to 7.21 with recovery to about 7.30. Arterial standard bicarbonate levels increased from 23 to 28 mM./liter during exposure to 60 ram. Hg CO₂ and to near 31 mM./liter, during exposure to 90 mm. Hg P_co2. A comparison of data from the present experiment with that obtained by Schwartz, et al. 4 with chronic hypercapnic dogs at ground level pressure suggested that our hypobarlc exposed dogs exhibited a slightly higher arterial standard bicarbonate resulting in a slightly greater arterial pH for a given arterlal P_co2 level.

Abstract

Although the galactic radiation level at SST altitudes is such that, from a radiological standpoint, exposure appears entirely unobjectionable, the prospect of large-scale commercial passenger operations calls for accurate assessment of the radiation load to the individual crew member and passenger and to the population as a whole. The maximum dose rate of about 1 millirem/hour at 65,000 feet in the polar region for 600 hours per year at altitude leads to a yearly dose of 0.6 rein, which exceeds the Maximum Permissible Dose (MPD) for “Members of the Public”(0.5 rem/year) by 20 per cent but constitutes only 12 per cent of the MPD for “Kadlatiou Workers” (5 rein/year) in terms of official regulations. On the other hand, shifting all jet travel to SST altitudes would still keep the additional radiation burden for the total population at the level of a few per cent of the fallout exposure although the individual passenger would accumulate the yearly fallout dose in about 25 hours at altitude. Radiobiologically, special consideration has to be given to heavy nuclei because of their high values of Linear Energy Transfer (“mlcrobeams”). However, the small fraction of the heavy flux, which carries the “microbeam” effects, undergoes a substantially higher absorption in the atmosphere than does the total flux. The mierobeam effectiveness of galactic primaries, therefore, is virtually extinguished at SST altitudes.

Abstract

Three colors of aircraft instrument illumination (aviation red, unfiltered white, blue-filtered white) were compared to determine their effects on (1) post-exposure, scotopic absolute and acuity thresholds, and (2) legibility for the reading of instruments. A simulated T-38 instrument panel, illuminated by light from incandescent instrument lamps, was used for light exposure. Results were: (1) at a low instrument panel luminance of 0.01 ft-L,absolute thresholds did not differ after exposure to the three colors of lighting, but scotopic acuity thresholds were somewhat lower after exposure to red light than after exposure to either unfiltered or blue-filtered white; (2) at a lumiance of 0.05 ft-L, both absolute and acuity thresholds were lower after exposure to red light than after exposure to unfiltered and blue-filtered white; and (3) the luminances required for the legibility of transillumihated letters of various sizes were about the same for red, unfiltered white and blue-filtered white instrument lighting. When extraneous sources of illumination can be controlled, it is recommended that those aircraft which might be used in night-tlme visual reconnaissance mission be equipped with a dual red/white instrument lighting system.

Abstract

Thirty-six young men were exposed for two hours to environmental temperatures of 10° 26.7° or 46°C Measurements of rectal, and skin temperatures, heart rate and respiratory rate were made, and average skin and average body temperatures were calculated. Manual performance consisted of standardized peg tests for hand and finger dexterity, and a written motor coordination test. Converted scores showed no significant differences in peg placing at any of the thermal states studied. Men exposed to the neutral environment scored highest in the finger dexterity tests, but values for motor coordination were greater in the heat than in the other two environments. These data suggest that coarse hand movements are independent of body thermal state, but that nmre discrete tasks involving hand and finger dexterity, and motor coordination, can be most efficiently performed in warmer environments which promote at least thermally neutral values of skin and deep body temperature.

Abstract

Whole-body supralethal doses of radiation produce a significant decrease in blood pressure and cerebral blood flow within minutes following irradiation. Nine Macaca mulatta monkeys were exposed to a head only dose of 2,500 rads of 6 Mev X-ray at a dose rate of 644 r/min. Five animals served as sham-irradlated controls. Cerebral blood flow, blood pressure, and systemic arterial and cerebral venous blood gas measurements were made just prior to and during the hour following irradiation.Cerebral blood flow was calculated from desaturation curves using the inert radioactive isotope Krypton 85. A small but significant decline in blood pressure was found immediately after irradiation with no significant change in cerebral blood flow. It was concluded that the hypotension and decreased cerebral blood flow observed after whole-body radiation exposure are not due primarily to a direct effect of radiation on the central nervous system.

Abstract

Slow time-varying pressure changes in the external auditory meatus were correlated with a variety of eye movements, including nystagmus, in the guinea pig. These responses were eliminated following eighth nerve section but were retained after destruction of the cochlea by loud sound. The observations are interpreted as supporting the hypothesis that acoustical stimuli may activate the receptors of the vestibular apparatus. Various possible mechanisms of acoustical vestibular stinmlation are discussed.

Abstract

To determine how severely the desert sun may affect aircrews and maintenance crews, experiments were done in and around parked F-10Ws and B-57’s on five, different days with clear skies from 0800 to 1600. Globe temperatures were measured in the cockpits as were surface temperatures around the cockpits. Temperatures of separate squares of aircraft skin painted black,green, orange and white were also measured. These data were compared to weather station data taken under standard meteorological conditions. Weather station temperatures did not exceed 32 C (90°F) but globe temperatures in closed cockpits reached 71° C (160 ° F) and temperatures of black paint and green camouflage paint exceeded 60 ,C (140 ° F). Globe temperatures in air 0.6 m above the parking raanp and all aircraft temperatures including that of unpainted surfaces exceeded the thermal pain and burn threshold (45 ° 'C, 113 ° F) for most of the daylight hours. Only white painted surfaces remained below 40 C (104 ° F). Shading reduced all temperatures to those of the ambient air. These data show that routine meteorological reports, which include only air temperature, hmnldity, wind and sky conditions, are grossly inadequate for predicting thermal stress under the eonditlons of the experiment. Aircrews and maintenance crews experience substantial heat stress and' discomfort that might be easily prevented by shading. Painting aircraft any color other than white markedly increases the heat content increasing the heat stress on occupants or personnel working on the plane.

Abstract

Indentation tonometry has been included routinely in the annual medical evaluation of senior flight personnel at United Air Lines for the past decade. During this period, more than fourteen thousand individual examinations have been accomplished on 2,046 pilots between 40 and 60 years of age. Fortynine cases of confirmed ocular hypertension were detected for a cumulative 10 year incidence of 2.4 percent. Among these cases, nine were eventually diagnosed as chronic simple glaucoma representing only 0.44 percent of those studied. Drug therapy, where indicated, was well tolerated with effective pressure control, and visual field losses were minimal in extent and well contained. There were no cases in which grounding was required. The results confirm the value and safety of routine tonometry in aviation medicine, but indicate that the prevalence of occult pathology which can be demonstrated thereby has been exaggerated in the commercial pilot population.

Abstract

Pacific Air Forces' experience with over 200,000 patient movements on combat airlift aircraft, both in Vietnam and throughout the Pacific theater, is reviewed. Over 40 percent of the movements were of individuals with combat incurred wounds.Specific criteria used for screening patients at casualty staging facilities to assure successful evacuation and prevent complications give special attention to: proper lung expansion after surgery in thoracic wounds, prevention of distention and ileus in abdomlnal wounds, the availability of suction for laryngeal, thoracic and abdominal wounds, the provision of adequate drainage, the proper hydration of all patients, the assurance of clear lungs and no constrictive circular dressings in burn cases. Special provisions must also be made for craniocerebral injuries, for the change of dirty dressings and for the bivalvlng of all casts if not already done. Only 13 deaths occurred in flight, all in moribund patients.

Abstract

The effectiveness of a drug in reducing susceptibility to acute motion sickness is readily determined in a Slow Rotation Room (SRR) where the stressful Coriolis accelerations are under quantitative control and the experimenter and subject can collaborate under laboratory conditions. Fifty subjects were used, each serving as his own control in evaluating 16 representative antimotion sickness drugs. Only the drugs with a sympathomimetic or parasympatholytic action and some of the antihistamines were notably effective. The summation effect of dextroamphetamine sulfate and 1-scopolamine hydrobromide provided far better protection than any single drug. Other classes of drugs had either a slightly favorable or slightly unfavorable action.

Abstract

Four cases of aseptic bone necrosis are presented. These cases, plus those of other authors, are analyzed in relation to distribution of lesions, previous history of decompression sickness, diving history, and other possible contributing factors. The author recommends abandoning the notion that this disease does not occur with the use of accepted diving procedures until a sdentlfie investigation of the occurrence of this disease is made.

Abstract

Aviation accidents attributable to coronary artery disease have always generated undue publicity and alarm. Some workers in the field believe that flying (total hours flown) as well as type of aircraft affect the health of the coronary arteries. The present study concerns 206 autopsied military pilots with varying degrees of coronary atheroselerosls. The data demonstrate that the amount of flying time (when the age factor is considered) and type of aircraft are neither statistically related nor contributory to the severity of coronary atheroselerosls in pilots. Furthermore, a 10 per cent random sample of all nfilitary aviation accidents aecessioned at the Armed Forces Institute of Pathology from 1958 through 1963 demonstrates that coronary artery disease has a causal relationship to 0.4 per cent of military aviation accidents. A plea is made for extreme conservatism in implicating coronary artery disease in an otherwise unexplained aviation accident. Drastic elimination of older aircrew will not significantly reduce aviation accidents.

Abstract

The rapid filling period of the left ventricle can be studied in intact individuals by apexcardiography. Its duration is of particular diagnostic and functional importance in assessing flow across the mitral valve. Yet, even cardiac catheterization records it only in the presence of diastolic restriction syndromes.

Data on the normal rapid filling period (KFP) are scant and disparate. The RFP was measured from the rapid filling wave of the apexcardiogram in 47 normal, active male subjects, aged 22 to 3.5 years. Values obtained were: 80-120 msec, mean, 99.8 ± 14.2 msec (1 S.D.).