| || Frostbite : Suspectibility Prevention and Immediate Treatment
Author : Selvamurthy, W. ;Purkayastha, S.S.
Source : Defence Science Journal ; Vol:49(5) ; 1999 ; pp 371-380
Subject : 612 Physiology;61 Medical Sciences
Keywords : Acclimatisation ;Cold induced vasodilatation;Cold injury;Frostbite
Abstract : "Frostbite, the severest form of cold injury, is a major health hazard and a serious medical problem for the Armed Forces operating in snow-bound areas at high altitudes. Detailed experiments on susceptibility, prevention and treatment were conducted to find out suitable measures to prevent, treat and ameliorate cold injuries. Experiments conducted on monkeys have shown that animals with higher peripheral vascular response are better protected against cold injury. Measurements of cold-induced vasodilatation (CIVD), heat output and peripheral blood f1ow under local cold stress can be used to screen out highly prone individuals to frostbite. Cold acclimatisation was effective in raising the peripheral vascular response and thereby lessening the degree of injury. Frostbite having occurred, its treatment is not very satisfactory. This is primarily due to the time lag between occurrence of frostbite and initiation of therapy, which plays a vital role in its curative action. Keeping this in view, many experiments have been conducted on this treatment. Pilot studies were carried out using various drugs and vitamins, and also procedures like rapid rewarming in warm water, tea decoction, turnip (shalgum) decoction, etc., singly as well as in combination, for treatment. The most encouraging result was obtained by the procedure of rapid rewarming in tea decoction maintained at 37-39 °C immediately after cold exposure, followed by combined therapy of aspirin (5 mg/kg) and pentoxifylline (40.mg/kg) along with vitamin C (50 mg/kg) twice daily for 7 days. "
| || Soldier at High Altitude: Problems and Preventive Measures
Author : Purkayastha, S.S.;Selvamurthy, W.
Source : Defence Science Journal ; Vol:50(2) ; 2000 ; pp 183-198
Subject : 57.089 Biomedical Sciences ;612 Physiology;61 Medical Sciences
Keywords : High altitude;Pulmonary oedema;Hypoxia
Abstract : "Due to military and strategic reasons, a large body of troops is being regularly deployed in the snowbound areas throughout Himalayan regions to guard the frontiers. The mountain environment at high altitude (HA) consists of several factors alien to plain dwellers, which evoke a series of physiological responses in human system. Some of the sea level residents on induction to HA suffer from several untoward symptoms of HA ailments varying from mild-to-severe degrees. Sudden exposure is detrimental to physical and mental performance of the low landers and in certain cases, may even lead to dreaded condition like high altitude pulmonary oedema (HAPO). These may make a man disturbed physically and mentally. So, there is a need to prevent such hazards which is possible if the individual is aware of the problems and preventive measures of HA ailments in advance, before going to HA for a safe and happy living there. Hence, a noble effort has been made to provide guidelines to create awareness about physical and physiological problems of life at HA and the methods of protection against its ill-effects for the soldiers, mountaineers and soldiers journers conducting scientific trials at HA. In this review, an attempt has been made to describe vital aspects of HA in a popular way, starting with its concept and various environmental factors which exert considerable effects on human body functions, health and performance on exposure to such environment, on the basis of a series of studies conducted at It the Defence Institute of Physiology & Allied sciences, Delhi, over the years. The most important featurel of HA (3,000 m and above) is hypoxia or deficiency of oxygen in the body. Other environmental factors are: severe cold, high velocity wind, low relative humidity, high solar radiation, increased ultraviolet radiation and difficult terrain. These factors are responsible for various HA and cold syndromes, viz., acute mountain sickness, HAPO, dehydration, sunburn, snow-blindness, CO-poisoning, hypothermia and cold injury of the extremities. "
| || Changes in plasma leptin and zinc status of women mountaineers at high altitude
Author : Suri, Shobha ;Salhan, Ashok ;Singh, Som Nath ;Selvamurthy, W.
Source : Defence Science Journal ; Vol:52(2) ; 2002 ; pp 173-179
Subject : 61 Medical Sciences
Keywords : Leptin ;Medical science ;Alkaline phosphatase
Abstract : "The loss of body weight due to suppressed appetite at high altitude is very common. The hormone leptin and trace metal zinc have key roles in appetite regulation. In the present study, changes in leptin and zinc status of female mountaineers with and without supplementation with zinc have been investigated. Plasma leptin, zinc and enzyme activities of alkaline phosphatase (EC 220.127.116.11) and 5' nucleotidase (EC 18.104.22.168) of 25 women mountaineers between age group 17-25 yr were studied. The women mountaineers were divided into two groups, i.e., placebo control (n = 7) and supplemented with zinc at dose 15 mg/day for 21 days (n = 18) and all variables were analysed initially at 1981 m, at high altitude (4572-5182 m) and on return to initial altitude. The basal leptin level for both the groups combined was 3.12 ± 0.57 ng/ml (mean ± SD). Plasma leptin levels were found increased by 24 per cent and 58 per cent, respectively at high altitude and after return in case of control group, whereas in case of zinc-supplemented group, there was a statistically non-significant decrease of 20 per cent at high altitude in comparison to basal values. Thereafter, levels were maintained at baseline. There was no significant change in zinc status of control group as indicated by plasma zinc as well as maintained activities of alkaline phosphatase and 5' nucleotidase in the present study. On the other hand, zinc-supplemented group showed increase in zinc status at high altitude, which was evident by increased plasma zinc levels. On return from high altitude, plasma zinc levels were low in comparison to high altitude but still higher than that of basal. Results indicate beneficial effects of zinc supplementation by decreasing leptin levels at high altitude. "
| || Regression of Body Density on Skinfold Thicknesses in High Altitude Natives: Decline in the Predictive Efficiency on De-Acclimatisation to Low Altitude
Author : Selvamurthy, W. ;Rao, T.L.;Dimri, G.P.;Chaudhary, K.L.;Prasad, J.;Pramanik, S.N.;Kishnani, S.;Zachariah, T.;Bharadwaj, H.
Source : Defence Science Journal ; Vol:45(3) ; 1995 ; pp 237-242
Subject : 57.089 Biomedical Sciences
Keywords : De acclimatisation ;Anthropometric measurements
Abstract : Body density, stature, body weight and skinfold thickness at 11 sites were experimentally measured on two groups of high altitude natives (HAN) of Ladakh. Group 1, consisting of 38 similar volunteers was studied after 4-week stay at an altitude of 3658 m and Group 2, consisting of 38 similar volunteers was studied after 4-week stay at Delhi (altitude, 200m). Although, there was a strong relationship between skinfolds, other anthropometric measurements and body density (R=0.898) at high altitude (HA), this relationship was significantly reduced at Delhi (R=0.642). Appropriate regression equations predicting body density from skinfold thicknesses, stature and body weight are given for HAN at both the locations. It is concluded that hyperhydration of the lean body and the adipose tissue may be responsible for the weakening of the multiple Rs on de-acclimatisation to low altitude.
| || Cold Acclimatization of Tropical Men during Short and Long Term Sojourn to Polar Environment
Author : Selvamurthy, W. ;Majumdar, D.;Purkayastha, S.S.
Source : Defence Science Journal ; Vol:47(2) ; 1997 ; pp 149-158
Subject : 61 Medical Sciences;612 Physiology
Keywords : Cold stress ;Cold acclimatization
Abstract : This study was undertaken to assess the status of cold acclimatization (CA) resulting from short- and long-term exposure of tropical men to severely cold environment of the Arctic and the Antarctic regions. Five Groups (seven each) of male subjects participated in this study. Cold-induced vasodilatation (CIVD) response was elicited during immersion of the right hand in cold water at 4 degree centigrade for 30 min at both the polar regions to evaluate peripheral CA. The 'standard cold test' at 10 degree centigrade for 2 hr was administered at the Arctic region on tropical and arctic residents and the data were compared with those for tropical men monitored at Delhi to ascertain the level of general CA. Group A (control) was studied at Delhi (29 degreeN, 77 degreeE) while Groups B and C were sailed to Antarctica (70 degreeS,11.5 degreeE). Their CIVD responses were monitored during thirteenth month and seventh to eighth week of stay, respective1y .There was no deliberate cold exposure, except during their 'occupation demand' outdoor duties. However, outdoor exposure for Group C was more. Group D was airlifted to the Arctic (70 degreeN, 38 degreeE) and studied during the seventh week of acclimatization. The subjects had regular deliberate cold exposure. For comparison, Group E of arctic residents was studied at the Arctic Group B did not show any adaptive modification to cold even after an year of sojourn in antarctic environment compared to Group A; while Group C subject, despite their short stay showed better CIVD response. Group D subjects recorded significant improvement in the response of general cold exposure as well as peripheral vascular response to local cold stress; their responses were comparable to those of the arctic residents (Group E). It is evident that human CA is impossible just by living in the coldest region of the globe even for prolonged periods. Deliberate regular exposure to atmospheric cold is the mandatory factor in developing human CA, the degree of which is related to the intensity of cold exposure.
| || Biomedical Applications of Simulated Environments
Author : Selvamurthy, W.
Source : Defence Science Journal ; Vol:43(3) ; 1993 ; pp 253-258
Subject : 57.089 Biomedical Sciences
Keywords : Environmental physiology;Human decomposition chamber;Portable oxygen regenerator
Abstract : Environmental physiology assumes great significance in our national context of the diverse climatic conditions prevailing in different regions. Troops have to operate in diverse environmental conditions guarding the frontiers. Hence, the research in this area has been focused on the usage of field studies in the natural environments or simulated environments in the laboratory. Besides, the application of the simulation chambers in the research on the physiological effects of diverse environments, these studies may have applications in the control and management of certain clinical disorders. Some simulation chambers and specilised set-ups have been designed and developed at the Defence Institute of Physiology and Allied Sciences to carry out simulation studies. This paper describes these developments and the potentials of these biomedical applications of simulated environments.
| || Neurophysiological Problems in Snow Bound High Altitude Areas
Author : Selvamurthy, W.
Source : Defence Science Journal ; Vol:34(4) ; 1984 ; pp 397-415
Subject : 61 Medical Sciences;612 Physiology
Keywords : Neurophysiological Response;Western Himalayas ;High Altitude Areas
Abstract : A series of studies have been conducted to evaluate the neurophysiological response in young healthy soldiers acclimatization at 3,500m altitude in Western Himalayas. The response of autonomic nervous system, electroencephalogram hypothalamic thermoregulatory efficiency, orthostatic tolerance, sleep profile and effects of sleep deprivation have been studied in fresh compared during three to five weeks of acclimatization at high altitude and compared with those of one year acclimatized lowlanders and high altitude natives. Physiological significance of these neurophysiological responses in the process of altitude adaptation is discussed in the light of current knowledge in the field.
| || Chemoreceptor sensitivity in women mountaineering trainees of different altitudes inducted by trekking to 4350 m
Author : Bhaumik, G.;Purkayastha, S. S.;Sharma, R. P.;Sharma, Y. K.;Selvamurthy, W.;Banerjee, P. K.
Source : Defence Science Journal ; Vol:55(4) ; 2005 ; pp 427-435
Subject : 57.089 Biomedical Sciences ;61 Medical Sciences;612 Physiology
Keywords : Hypoxic ventilatory response;Hypercapnic ventilatory response;High altitude;Chemoreceptor sensitivity
Abstract : This study was conducted on women mountaineering trainees to evaluate the hypoxic and hypercapnic ventilatory responses, and the precise nature of changes in the sensitivity of chemoreceptors on induction by trekking to 4350 m. Two groups of women belonging to different ethnic origins and residents of different altitudes, ie, moderate-altitude women (MAW- Mongolians) and low-altitude women (LAW-Caucasians) were the subjects in this study. Tests of sensitivity to hypoxia and hypercapnia were carried out initially at 2100 m, then during 4 to7 days of sojourn at 4350 m following induction by trekking, and re-tested on return to 2100 m. The results indicate that there is a significant difference (P < 0.05) of hypoxic ventilatory response in women of two different ethnic groups. Both hypoxic and hypercapnic ventilatory responses increased significantly (P < 0.05) on induction to high altitude. On descent, hypoxic values reverted back to pre-induction levels, whereas hypercapnic ventilatory response showed relatively higher values (P < 0.05).