Biomedical Applications of Simulated Environments .

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

A series of studies have been conducted to evaluate the neurophysiological responses in young healthy soldiers during acclimatization at 3,500m altitude in Western Himalayas. The responses of autonomic nervous system, electroencephalogram hypothalamic thermoregulatory efficiency, orthostatic tolerance, sleep profile and effects of sleep deprivation have been studied in fresh inductees 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

Frostbite - susceptibility, Prevention and Immediate Treatment

Frostbite, the severest form of cold injury, is a major health hazard and a serious medical problem for theArmed Forces operating in snow-bound areas at high altitudes. Detailed experiments on susceptibility, preventionand treatment were conducted to find out suitable measures to prevent, treat and ameliorate wld injuries.Experiments conducted on monkeys have shown that animals with higher  peripheral vascular response me betterprotected against cold injury. Measurements of cold-induced vasodilatation (CIVD), heat output and peripheralblood flow under local cold stress can be used to screen out highly prone individuals to frostbite. Coldacclimatisation was effective in raising the peripheral vascular response and thereby lessening the degree ofinjury. Frostbite having occurred, its treatment is not very satisfactory. This is primarily due to the time lagbetween occurrence of frostbite and initiation of therapy, which plays a vital role in its curative action. Keepingthis in view, many experiments have been wnductedon this treatment. Pilot studies were carriedoutusing variousdrugs 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 theprocedure of rapid rewarming in tea decoction maintained at 37-39 "C immediately after cold exposure, followedby combined therapy of aspirin (5 mgtkg) and pentoxifylline (40 mgkg) along with vitamin C (50 mglkg) twicedaily for 7 days

Chemoreceptor Sensitivity ‘in Women Mountaineering Trainees of Different Altitudes Inducted by Trekking to 4350 m

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 (MAWMongolians) 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 2 100 m. The results indicate that there is a significant difference (P c 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)

MORINDA COREIA HAS AN ANTI-HELICOBACTER PYLORI EFFECT AGAINST THE MULTIDRUG-RESISTANT CLINICAL ISOLATE OF NORTH-EAST INDIA

Objective: Antimicrobial resistance is a growing problem in Helicobacter pylori eradication which is a microaerophilic bacterium causing various gastroduodenal diseases. The present study has been designed to test the efficacy of Morinda coreia against the metronidazole clarithromycin and levofloxacin-resistant H. pylori strains isolated from the biopsy taken from the patient suffering from gastric erosion in Guwahati, Assam.Method: The antimicrobial activity of n-hexane and chloroform extract of M. coreia was tested against multidrug-resistant H. pylori isolate of Guwahati, Assam, by agar well method and microdilution method.Result: In the present study, the H. pylori strain resistant for metronidazole (minimal inhibitory concentration [MIC] >64 μg/mL), clarithromycin at (MIC >0.5 μg/mL), and levofloxacin at (MIC >1 μg/mL) was tested against the n-hexane and chloroform extract of M. coreia. Both the extracts of M. coreia showed good efficacy against the multidrug-resistant strain of H. pylori shown inhibition at 1.2 μg/mL with n-hexane extract and 2 μg/mL with chloroform extract of M. coreia. Conclusion: The prevalence of metronidazole-resistant ranges between 50% and 90% in the developing countries, including India, clarithromycin ranges from 0% to 15% in India, and levofloxacin ranges between 50% and 70% in India, so there is a need of alternative therapy for the eradication of this bacterium from the stomach. Hence, this study suggests that M. coreia, which has been used traditionally as a folk medicine for the treatment of many gastric diseases, has also shown good efficacy against the multidrug-resistant H. pylori strain of North-east India

Variations in angiotensin-converting enzyme gene insertion/deletion polymorphism in Indian populations of different ethnic origins

The pattern of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism in the Indian population is poorly known. In order to determine the status of the polymorphism, young unrelated male army recruits were screened. The population had cultural and linguistic differences and lived in an environment that varied significantly from one region to another. Analysis of the genotype, showed higher frequency of the insertion allele in four of the five groups i.e. I allele frequency was significantly higher (P<005) in Dogras, Assamese and Kumaonese. The deletion allele frequency was comparatively higher in the fifth group that belonged to Punjab. A correlation was observed between the genotype and enzyme activity. Involvement of a single D allele in the genotype enhanced the activity up to 37.56 ± 313%. The results suggested ethnic heterogeneity with a significant gene cline with higher insertion allele frequency. Such population-based data on various polymorphisms can ultimately be exploited in pharmacogenomics

Regression of Body Density on Skinfold Thicknesses in High Altitude Natives: Decline in the Predictive Efficiency on De-Acclimatisation to Low Altitude

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

Angiotensin converting enzyme insertion allele in relation to high altitude adaptation

Angiotensin converting enzyme (ACE) gene I/D polymorphism has been associated with high altitude (HA) disorders as well as physical performance. We, however, envisage that the polymorphism may be associated with adaptation to the hypobaric hypoxia of altitude, thus facilitating physical performance. For this purpose, three unrelated adult male groups, namely (1) the Ladakhis (HLs), who reside at and above a height of 3600 m, (2) lowlanders, who migrated to Ladakh (MLLs), and (3) resident lowlanders (LLs), have been investigated. The HLs had significantly (p<0.001) greater numbers of the II homozygotes and the ID heterozygotes than the DD homozygotes, the genotype distribution being 0.46, 0.43 and 0.11 for II, ID and DD genotypes respectively. The MLLs comprised 60% II homozygotes, which was higher (p<0.001) than the HLs (46%). In the LLs, the heterozygotes were greater (p<0.001) in number than the II and DD homozygotes. The I allele frequency was 0.72 in the MLLs, 0.67 in the HLs and 0.55 in the LLs. Polymorphism study suggested that the II genotype could be associated with altitude adaptation, which might influence physical efficiency

Arterial oxygen saturation under hypoxic environment of high-altitude associates with routine physical activities of natives

Per cent oxygen saturation of arterial haemoglobin levels (SaO2), a measure of hypoxemia has been analysed in the permanent residents of Ladakh. The population recognized as high-altitude controls (HAC) and high-altitudemonks (HAM), resided at the same altitude of 3600 m but differed in their routines. SaO2 was measured with a Finger-Pulse Oximeter. The HAM had 3.08% higher SaO2 (P<0.001) compared to the HAC, with mean SaO2 of 91.8°6.1% and 89.0°2.6%, respectively. Furthermore, the younger HAM also revealed an elevation of 4.55% SaO2 than the HAC of identical age (P<0.001). The HAM, who are less hypoxemic than their counterparts are physically more active, which may be a selective advantage in the extreme environment of higher altitudes

Does practicing hatha yoga satisfy recommendations for intensity of physical activity which improves and maintains health and cardiovascular fitness?

Background: Little is known about the metabolic and heart rate responses to a typical hatha yoga session. The purposes of this study were 1) to determine whether a typical yoga practice using various postures meets the current recommendations for levels of physical activity required to improve and maintain health and cardiovascular fitness; 2) to determine the reliability of metabolic costs of yoga across sessions; 3) to compare the metabolic costs of yoga practice to those of treadmill walking. Methods: In this observational study, 20 intermediate-to-advanced level yoga practitioners, age 31.4 ± 8.3 years, performed an exercise routine inside a human respiratory chamber (indirect calorimeter) while wearing heart rate monitors. The exercise routine consisted of 30 minutes of sitting, 56 minutes of beginner-level hatha yoga administered by video, and 10 minutes of treadmill walking at 3.2 and 4.8 kph each. Measures were mean oxygen consumption (VO2), heart rate (HR), percentage predicted maximal heart rate (%MHR), metabolic equivalents (METs), and energy expenditure (kcal). Seven subjects repeated the protocol so that measurement reliability could be established. Results: Mean values across the entire yoga session for VO2, HR, %MHR, METs, and energy/min were 0.6 L/kg/min; 93.2 beats/min; 49.4%; 2.5; and 3.2 kcal/min; respectively. Results of the ICCs (2,1) for mean values across the entire yoga session for kcal, METs, and %MHR were 0.979 and 0.973, and 0.865, respectively. Conclusion: Metabolic costs of yoga averaged across the entire session represent low levels of physical activity, are similar to walking on a treadmill at 3.2 kph, and do not meet recommendations for levels of physical activity for improving or maintaining health or cardiovascular fitness. Yoga practice incorporating sun salutation postures exceeding the minimum bout of 10 minutes may contribute some portion of sufficiently intense physical activity to improve cardio-respiratory fitness in unfit or sedentary individuals. The measurement of energy expenditure across yoga sessions is highly reliable