Body composition & cardiovascular functions in healthy males acclimatized to desert & high altitude.

BACKGROUND & OBJECTIVES: Several physiological changes affecting physical fitness occur in humans whenever they are exposed to extremes of environments such as heat, cold and high altitude (HA). The present study was undertaken to evaluate effect of stay in desert and HA on physical fitness and body composition of physically active individuals. METHODS: Study was conducted on three groups of male soldiers (n=30 in each group) at different climatic conditions i.e., temperate (plains of north India), hot desert (Rajasthan), and HA (3600 m) in Western Himalayas. Subjects were acclimatized to hot and HA environments and had similar BMI (body mass index). Body fat, lean body mass, haemoglobin levels were determined along with, blood pressure and physical fitness index (PFI). RESULTS: The body fat of subjects at temperate, desert and HA was found to be 15.4, 12.8 and 16.9 per cent respectively. The resting heart rate and blood pressure were higher in altitude group in comparison to others. PFI score of volunteers at temperate, desert and HA were found to be 97.4 +/- 10.3, 92.4+/- 14.4 and 83.8 +/- 6.2 respectively. INTERPRETATION & CONCLUSION: A combination of different factors i.e., higher resting pulse rate, increased blood pressure and body fat may be responsible for lower PFI at HA. The observed differences in body fat content of different groups could be an adaptive feature to the environment.

Effect of simulated ascent to 3500 meter on neuro-endocrine functions.

Ascent to extreme High Altitude (HA) is in steps and it entails acclimatization at moderately HA locations. In terms of acclimatization, it is pertinent to understand the physiological changes, which occur on immediate ascent to moderate HA. The study aimed to evaluate the effect of ascent to 3500 m on neuro-endocrine responses in the first hour of induction. The plasma levels of catecholamines and cortisol were measured before and after one hour of ascent to high altitude. The peripheral oxygen saturation (SpO2), Galvanic Skin Resistance (GSR), Heart Rate (HR) and Blood Pressure (BP) were simultaneously monitored. The plasma epinephrine, norepinephrine, dopamine and cortisol were increased after one-hour exposure to 3500 m altitude as compared to before exposure. The SpO2 showed a significant decrease during and after high altitude induction. The heart rate and diastolic BP increased at 3500 m whereas the GSR did not show significant changes. There are changes in neuroendocrine responses, which reflect a sympathetic over activity in the first hour of exposure to 3500 m.

Effect of hypobaric hypoxia on visual evoked potential at high altitude.

The effect of hypobaric hypoxia on visual evoked potential (VEP) was studied in 27 male volunteers at sea level (SL), during the 1st and 3rd weeks of their stay at high altitude (HA) of 3,500 m and in the 1st week of their return to the sea level (RSL). Exposure to high altitude (HA) led to significant changes in VEP. The N1 wave latency of both right and left eye was significantly increased (P<0.05) during 3rd week of stay at the altitude which persisted even after the return to the sea level. The latency of P1 wave of both right and left eye was higher in 3rd week at high altitude but not significant statistically. But the delay in P1 latency persisted in 1st week of their return to sea level which was significant (p<0.05) statistically as compared to sea level. The latency of N2 wave was significantly decreased (P<0.05) during the 1st week of stay at HA and returned back to basal value in the 3rd week of stay at HA in both right and left eye. However, the changes observed in NPN complex in terms of wave latencies were within the physiological limits. The amplitude of wave N1-P1 of both the right and left eye did not show any change. The changes observed reflect the process of acclimatisation to 3500m high altitude.

Changes in visual evoked potentials on acute induction to high altitude.

BACKGROUND & OBJECTIVES: Induction to high altitude leads to altered central nervous system (CNS) functions induced by hypobaric hypoxia. The sensory systems like visual and auditory systems are reported to be affected by hypoxia. The present study was undertaken to assess the effects of hypobaric hypoxia on visual evoked potentials (VEPs) at 3200 m and 4300 m. METHODS: The VEP of 30 human volunteers were recorded at sea level (SL) and then at high altitude (HA) of 3200 m (HA I) and 4300 m (HA II) in eastern Himalayas and on return to sea level (RSL). The absolute latencies and amplitude of positive and negative waves were recorded. RESULTS: High altitude of 3200 m did not alter the latency of major wave N1, P1 and N2 of the VEPs. At HA II (4300 m), there was a statistically significant increase (P < 0.01) in the latency of NI wave as compared to the SL value and HA I (3200 m) in both left and right eye. There was a slight increase in latenty of P1 wave in both left and right eye at HA II. INTERPRETATION & CONCLUSION: From these results it may be concluded that induction to HA causes increase in latency of N1 wave at 4300 m which is still within physiological limits. This increase in wave latency of N1 wave in both eyes may be due to synaptic delay and/or altered neuronal processing at HA.

Auditory evoked functions in ground crew working in high noise environment of Mumbai airport.

The continuous exposure to the relatively high level of noise in the surroundings of an airport is likely to affect the central pathway of the auditory system as well as the cognitive functions of the people working in that environment. The Brainstem Auditory Evoked Responses (BAER), Mid Latency Response (MLR) and P300 response of the ground crew employees working in Mumbai airport were studied to evaluate the effects of continuous exposure to high level of noise of the surroundings of the airport on these responses. BAER, P300 and MLR were recorded by using a Nicolet Compact-4 (USA) instrument. Audiometry was also monitored with the help of GSI-16 Audiometer. There was a significant increase in the peak III latency of the BAER in the subjects exposed to noise compared to controls with no change in their P300 values. The exposed group showed hearing loss at different frequencies. The exposure to the high level of noise caused a considerable decline in the auditory conduction upto the level of the brainstem with no significant change in conduction in the midbrain, subcortical areas, auditory cortex and associated areas. There was also no significant change in cognitive function as measured by P300 response.

Effect of chronic hypobaric hypoxia on components of the human event related potential.

BACKGROUND & OBJECTIVES: Induction to high altitude (HA) leads to deterioration in cognitive functions. The event related potentials (ERPs) like P300 are reported to be affected by hypoxia and bring about impairments in cognitive performance. The aim of the study was to investigate the effect of hypobaric hypoxia on event related potentials at two different altitudes i.e., 3200 m (HA I) and 4300 m (HA II) in ascending order to see how ERPs change with increasing altitude. METHODS: The study was carried out on 20 healthy male volunteers at sea level (SL) and thereafter at high altitude (HA) in Eastern Himalayas and on return to sea level (RSL). The P300 was recorded by using standard auditory odd ball paradigm with compact -4 (Nicolet, USA). RESULTS: The N1, N2 and P2 latencies were not significantly affected at HA I and HA II in comparison with SL indicating no effect of hypobaric hypoxia on sensory conduction. However, at HA II, most of the subjects showed an increase in latency of P3 component reflecting sensory discrimination and delay in evaluation process at 4300 m. At HA I, only 10 out of 20 subjects showed an increase in P3 wave latency and 3 did not show any change in N2-P3 components. INTERPRETATION & CONCLUSION: The results of the present study showed an increase in P300 wave latency at 3200 and 4300 m of high altitude. The observations suggest that hypoxia causes slowing of the signal processing at 4300 m, and magnitudes of the effects are altitude dependent with higher level of decline observed with increasing altitude.

Effect of high altitude on human auditory brainstem responses.

The effect of hypobaric hypoxia on Brain Stem Auditory evoked potentials (BAERs) were studied. BAERs were recorded in 30 volunteers at sea level (SL) and then at high altitude (HA) of 3200 m (HA I) and 4300 m (HA II) in Eastern Himalayas and on return to sea level (RSL). The BAERs were recorded using Nicolet Compact - 4 (USA) in response to monaural auditory stimuli consisting of clicks of 100 ps square pulse at a rate of 15/sec. The BAERs were recorded on day 4 of their stay at 3200 m and 4300 m respectively. Findings indicated an increase in absolute peak latencies of wave V at 3200 m, which was statistically significant. On further ascent to 4300 m there was an increase in absolute peak latencies of wave I and III indicating delay in sensory conduction at the medullo-pontine auditory pathways.

Effects of periodic weight support in a simulated weightless environment in preventing bone demineralisation.

Anti Orthostatic Hypokinetic posture in rats by tail suspension for 15 days (d) simulates the deconditioning effects of weightlessness on the weight bearing bones. The present study evaluates the effects of daily 4 hour (h) weight support (WS) during simulated weightlessness (S-W) in preventing these changes. Adult male albino rats were divided into three groups as (i) Control (CON, n = 12), (ii) Hind limb unweighing by tail suspension for 15 d (HU, n = 18), (iii) HU with daily 4 h WS (4 HRWS, n = 11). After 15 d tibia from all the animals were removed and subsequently dried, ashed and then calcium content of the bones were determined. HU showed reductions in the water content by 35.8%, organic matrix by 12.2% and calcium content by 33.4% of tibia. 4 h WS during S-W resulted in complete prevention of water loss and organic matrix loss and partial prevention of the loss of calcium content. Calcium content of tibia in 4 HRWS remained 15.2% less as compared to CON. These findings indicate that 4 h WS is partially successful in preventing the demineralisation effects of S-W on weight bearing bone tibia.

Oxygen saturation response to exercise VO2 at 2100 m and 4350 m in women mountaineering trainees.

Human work performances decreases at high altitude (HA). This decrement does not appear to be similar for every individual, may be due to variety of factors like elevation, mode of induction, work intensity, physical condition and specificity of the subjects. The purpose of the study was to evaluate the effects of alteration in responses of oxygen saturation (SaO2) and oxygen consumption (VO2) to a standard exercise in women mountaineering trainees under hypobaric hypoxia. Experiments were conducted in 2 groups (10 each) of females and compared the difference in responses of native women of moderate altitude with those of the plains/low altitude. A standard exercise test (Modified Harvard Step-Test for women) was performed on a 30 cm stool with 24 cycles/min for 5 min, initially at 2100 m and then at 4350 m. The exercise VO2 values for plains dwelling women achieved apparently VO2max level at both altitude locations with significant reduction in SaO2 during standard exercise. Exercise VO2 values decreased on exposure to 4350 m with further reduction in SaO2. Whereas with same work intensity, under same situation the exercise VO2 values of the moderate altitude women did not appear to have reached VO2max. They also maintained comparatively higher level of SaO2. It may be concluded that hypoxic exposure along with mountaineering training, the moderate altitude women maintained a higher level of SaO2 during standard exercise at both altitude locations, compared to low altitude women who might have lost a compensatory reserve to defend the hypoxic stress to exercise. Thus, moderate altitude women are proved to be better fit for hypoxic tolerance/HA performance.

Immediate treatment of frostbite using rapid rewarming in tea decoction followed by combined therapy of pentoxifylline, aspirin & vitamin C.

BACKGROUND & OBJECTIVES: Frostbite, the severest form of cold injury is a serious medical problem for our Armed Forces operating in the snow bound areas at high altitude. Effects of treatment by rapid rewarming in tea decoction followed by combined therapy of pentoxifylline, aspirin and vitamin C were evaluated in amelioration of tissue damage due to experimentally induced frostbite in rats. METHODS: Experiments were conducted in 2 groups (25 each) of albino rats (control i.e., untreated and experimental i.e., treated). Frostbite was produced experimentally in all the animals by exposing one of the hind limbs at -12 +/- 1 degree C with wind flow 25-30 lit/min for 30 min in a freezing-machine, with simultaneous recordings of rectal and ambient temperatures. The degree of tissue damage was assessed after 10 days. Following cold exposure, neither external thawing nor any medication was given to the animals of the control group; while the exposed limb of the experimental animals was rewarmed in tea decoction maintained at 37-39 degrees C for 30 min immediately after cold exposure, with simultaneous oral ingestion of warm tea decoction. These animals were also given pentoxifylline (40 mg/kg), aspirin (5 mg/kg) and vitamin C (50 mg/kg) twice daily orally for the next 7 days. RESULTS: In the control group, 68 per cent animals suffered from severe (56%) to very severe (12%) frostbite, while the remaining 32 per cent had moderate frostbite. No animals of this group could escape injury or suffered anything less than moderate frostbite; whereas 52 per cent of experimental animals escaped injury (no frostbite) and 32 and 16 per cent suffered only with primary and moderate degree of injury, respectively. None from this group suffered from severe or very severe frostbite. INTERPRETATION & CONCLUSION: It is evident from the study that this combined therapy resulted in significant improvement in the degree of tissue preservation and proved to be highly beneficial as an immediate treatment of frostbite in rats. The combined pharmacological properties of these drugs might have altered the haemorrheologic status of blood and produced curative beneficial effect in improving tissue survival. Clinical studies are required for confirmation of these beneficial effects in humans, which has already been taken up.

Sleep and performance--recent trends.

Sleep and sleep deprivation are intimately related to performance. Sleep management of people working in different sectors of the society like multi shift workers, nurses, doctors, students in professional schools and the armed forces has a great bearing on performance, health and safety of the subject population. The detrimental effects of sleep deprivation on psychological performance are indicated as increased lapsing, cognitive slowing, memory impairment, decrease in vigilance and sustained attention and shift in optimum response capability. Its effects on physical performance are manifested as decline in ability to perform maximal exercise, self-selected walking pace and increase in perceived exertion. Sleep deprivation appears to have no effect in respect of muscle contractile properties and maximum anaerobic power. At high altitude (HA), there is a reduction in NREM sleep with frequent awakening due to hypoxia as a physiological adaptive measure to prevent accentuation of hypoxemia due to sleep-hypoventilation. Total sleep deprivation for 48 hours at high altitude can affect the acclimatization status, thermoregulation efficiency and cognitive functions. The concept of 'sleepiness' has also been studied, as it is an emerging concept for better understanding of the effects of sleep deprivation and its effects on performance. A special mention of sustained operations in the armed forces has been made keeping in mind its uniqueness in challenging the normal sleep-work schedule and its deployment in extreme environment and operational condition. This article reviews in detail the functions of sleep, its requirement and the effects of sleep deprivation on human performance.

Treatment of chronic anal fissure with topical glyceryl trinitrate: a double-blind, placebo-controlled trial.

BACKGROUND: Topical glyceryl trinitrate (GTN) may produce healing of anal fissure by decreasing the high resting anal sphincter pressure in these patients. The present study assessed the efficacy of GTN in chronic anal fissure in a double-blind placebo-controlled trial. METHOD: Patients with chronic anal fissure (for more than 8 weeks) underwent measurement of maximum anal resting pressure (MARP) before and 12 minutes after application of either 0.2% GTN or placebo ointment in a randomized manner. They then received twice-daily local application of their respective ointment for 6 weeks. Symptoms and healing of fissure were assessed; patients were evaluated at 3 months for evidence of relapse. RESULTS: 19 adult patients (12 men) were studied; 10 received GTN and 9 placebo. Mean (SD) MARP decreased from 131.0 (32.3) cm H2O to 93.5 (28.4) cm H2O (p<0.05) with GTN and from 150.5 (36.9) cm H2O to 142.8 (35.0) cm H2O (p=ns) with placebo. Fissure healed in 7 of 10 patients treated with GTN and 2 of 9 patients treated with placebo (p<0.05). There was no relapse of fissure in either group. CONCLUSION: Local application of GTN was effective in healing chronic anal fissure.

Etiology and management of obscure gastrointestinal bleed--an appraisal from eastern India.

OBJECTIVES AND METHOD: Forty patients (mean age 45 years; 24 men) attending a tertiary care hospital in eastern India during the period 1996-2000 were investigated to evaluate the etiology and clinical spectrum of obscure gastrointestinal bleed. RESULTS: The patients presented to hospital after mean symptom duration of 2.5 years. They had received an average of 15 units of blood transfusion. Most patients presented with recurrent melena (85%); all had iron-deficiency anemia. A total of 230 investigations (89 gastroscopies, 54 colonoscopies, 25 double-contrast meal and follow-through studies, 14 small bowel enemas, 24 radionuclide scans, 16 mesenteric angiographies and 8 intraoperative endoscopies) yielded positive diagnosis in 87.5% of cases. The diseases encountered were small bowel and colonic angiodysplasias (32.5%), ileal Crohn's disease (20%), intestinal tuberculosis (10%), intestinal tumors (10%), nonspecific small bowel ulcers and strictures (7.5%), Meckel's diverticulum (5%) and hemobilia (2.5%). The etiology remained obscure in 5 (12.5%) cases. Overall success of surgery was 63%; in-hospital mortality was 7.5%. CONCLUSION: Though obscure gastrointestinal bleed is commonly caused by angiodysplasias, it can be an atypical presentation of Crohn's disease.

Is immunoproliferative small intestinal disease uncommon in India?

Till date only three series of immunoproliferative small intestinal disease (IPSID) describing 22 patients have been reported from India. Seven patients with IPSID in two tertiary referral centers in India are included in the study. Diagnosis was based on typical clinical features [diarrhoea (7/7), weight loss (7/7), clubbing (6/7), fever (3/7), abdominal pain and lump (3/7)], biochemical evidence of malabsorption and duodenal biopsy findings. All patients were young males (mean age 29.8 +/- 11.8 years, range 17-53). Atypical features included gastric involvement (1/7), colonic involvement (1/7) and appearance of pigmented nails following anti-cancer chemotherapy (1/7) which disappeared six months after omitting doxorubin from chemotherapy regimen. Parasitic infestation was common. Ascaris lumbricoides (1/7), Giardia lamblia and hookworm (1/7), Strongyloides stercoralis and Trichuris trichura (1/7). In the latter patient S. stercoralis became disseminated after anti-malignant chemotherapy. One patient had gastric H. pylori infection. Four of the seven patients who were misdiagnosed as tropical sprue were treated with tetracycline. This raises doubt on efficacy of tetracycline alone in treatment of IPSID. One other patient was misdiagnosed and treated as intestinal tuberculosis. Early diagnosis and administration of chemotherapy may improve survival in this disease.

Colonic mucosal changes in portal hypertension.

Forty one consecutive patients with portal hypertension (PHT) were evaluated by colonoscopy to study the prevalence, type, extent and predictors of haemorrhoids, colorectal varices, and portal hypertensive colopathy. Specific inquiry and regular follow-up assessed frequency of hematochezia. Twenty five patients with obscure gastrointestinal bleeding without PHT who underwent colonoscopy served as controls. Haemorrhoids were seen in nine of 41 (21.9%) patients with PHT and four of 25 (16%) controls (p = ns). Colorectal varices were seen in 13/41 (31.7%) patients with PHT and none of the controls (p = 0.005). Portal colopathy was present in 15/41 (36.6%) patients with PHT and none of the controls (p = 0.0005). None of the parameters (e.g. aetiology of PHT, Child's class, oesophageal variceal eradication by EST with or without EVL, history of variceal bleeding, grade of oesophageal varices, presence of portal hypertensive gastropathy or gastric varices) predicted the occurrence of colorectal varices and portal hypertensive colopathy. Detection of colorectal varices but not portal hypertensive colopathy was associated with occurrence of hematochezia.

Bone changes during simulated weightlessness in rats.

Weightless environment due to prolonged Space mission results in decreased mineralisation of the weight bearing bones. Hind limb unweighting (HU) in rats by tail suspension was used to simulate the effect of weightlessness on tibia. Adult male albino rats were divided into two groups as (i) Control (CON, n = 12) and (ii) HU for 15 days (HU, n = 18). After 15 days of HU tibia from all the animals were removed and subsequently dried and ashed. The calcium content of these bones were then determined. HU resulted in atrophic changes in the weight bearing bone, tibia, due to the reductions of water content (-35.8%), organic matrix (-12.2%) and calcium content (-33.4%). The reduction in the dry wt of tibia (-13.5%) was due to proportionate reductions in the organic matrix and total mineral content of the bone. The reduction in the mineral content was solely due to the reduction in calcium content of the bone.

Aetiological spectrum of chronic liver disease in eastern India.

AIM: To evaluate the aetiologic spectrum of chronic liver disease (CLD) in a tertiary referral center in Eastern India. METHODS: A total of 175 patients (cirrhosis 166, chronic hepatitis 9) diagnosed by clinical, biochemical, radiological and histopathological (42 cases) parameters were evaluated for aetiology. Investigations included: HBsAg and anti HCV (third generation) by ELISA. HBeAg and HBV DNA were tested in HBsAg positive patients. HCV RNA was tested in anti-HCV positive patients. Markers for autoimmune and Wilson's disease (anti-nuclear antibody, anti smooth muscle antibody, serum ceruloplasmin, urinary copper and slit lamp examination for KF ring) were done where clinically indicated. RESULTS: A total of 62 (35.4%) patients had HBV related CLD and 6 (9.7%) of them had pre-core mutant. HCV was present in 17/114 (14.9%) cases and none had infection with both viruses. Autoimmunity, Wilson's disease and alcohol were the aetiological factors in 5 (2.8%), 5 (2.8%) and 3 (1.7%) patients respectively. No aetilogy could be found in 18/114 (15.8%) patients. CONCLUSIONS: It is concluded that HBV is the commonest cause of CLD in Eastern India. Alcohol and HCV are uncommon in this part of the country.

Oxidative stress in gastric mucosa in Helicobacter pylori infection.

BACKGROUND: Infection with Helicobacter pylori is believed to be associated with generation of reactive oxygen molecules which leads to oxidative stress in the gastric mucosa; but the relation between oxidative stress and gastrointestinal mucosal damage has not been documented. AIM: To look for evidence of oxidative stress and lipid peroxidation in the gastric mucosa in H. pylori-associated peptic ulcer. METHODS: 34 duodenal ulcer (DU) patients with H. pylori infection, 14 DU patients without H. pylori infection and 10 healthy subjects without H. pylori infection were studied. H. pylori infection was diagnosed by histology and rapid urease test on endoscopic biopsies from the gastric body and antrum. Reduced glutathione (GSH) and malondialdehyde (MDA) content were measured in biopsies taken from the gastric antrum. Statistical analysis was done using Student's t test. RESULTS: Tissue levels of GSH were significantly lower (91.7 [35.4] nmole/100 mg versus 147.3 [41.2] nmole/100 mg; p < 0.001) and MDA higher (163.0 [83.4] nmole/100 mg versus 109.2 [51.3] nmole/100 mg; p < 0.01) in patients with DU associated with H. pylori infection as compared to those without H. pylori infection. GSH levels were significantly lower and MDA levels higher in DU patients with or without H. pylori infection as compared to control subjects. Serum MDA levels in DU patients with H. pylori infection were also significantly higher than in patients without H. pylori infection. CONCLUSION: Depletion of gastric mucosal glutathione in H. pylori-infected DU patients may be due to failure of the antioxidant defense system. Failure of the glutathione-dependent defense system results in accumulation of free radicals which can initiate membrane damage by lipid peroxidation.