Acclimatization at high altitude in gradual and acute induction.

The study assessed physiological responses to induction to high altitude first to 3,500 m and then to 4,200 m and compared the time course of altitude acclimatization in two groups of male volunteers. The acutely inducted group was transported by aircraft (AI) to 3,500 m in 1 h, whereas the gradually inducted group was transported by road (RI) in 4 days. Baseline recordings of basal cardiovascular, respiratory, and blood gas variables were monitored at sea level as well as at 3,500 m on days 1, 3, 5, and 7. Blood gases were measured on day 10 also. After 15 days at 3,500 m, the subjects were inducted to 4,200 m by road, and measurements were repeated on days 1, 3, and 5, except blood gas variables, which were done on day 10 only. Acute mountain sickness symptoms were recorded throughout. The responses of RI were stable by day 3 of induction at 3,500 m, whereas it took 5 days for AI. Four days in transit for RI appear equivalent to 2 days at 3,500 m for AI. Acclimatization schedules of 3 and 5 days, respectively, for RI and AI are essential to avoid malacclimatization and/or high-altitude illness. Both groups took 3 days at 4,200 m to attain stability for achieving acclimatization.

Experimental studies on the treatment of frostbite in rats.

The effect of treatment by high dose of vitamin C, rapid rewarming by 37 degrees C water alone and with vitamin C, rapid rewarming by 37 degrees C decoction of Indian black tea alone and with vitamin C for experimentally produced frostbite was evaluated in 6 groups (25 each) of rats. Frostbite was produced experimentally in the hind limbs by exposing the animals at -15 degrees C for 1h using the harness technique. The degree of injury was assessed and classified on the basis of tissue necrosis at the end of 15 days. Administration of high dose of vitamin C for prolonged period and rapid rewarming at 37 degrees C water bath immediately after cold exposure apparently reduced the tissue damage. High dose of vitamin C therapy preceded by rapid rewarming in plain water showed additional benefit. Rapid rewarming in decoction of Indian tea resulted in identical beneficial effect. The degree of tissue preservation was highest with rapid rewarming in tea decoction followed by high dose of vitamin C.

Hormone profiles at high altitude in man.

Altitude induced alterations in circulatory levels of PRL, LH, FSH and testosterone were studied in seven eugonadal men at sea level (SL), during their stay at high altitude (HA, 3500 m) and a week after return to SL. The mean plasma PRL level at SL was 5.83 +/- 1.7 SE ng/ml. On day one and seven of arrival at HA, the PRL values of 7.81 +/- 1.81 and 9.21 +/- 1.64 ng/ml respectively were not significantly different (p greater than 0.05) than the initial SL values. However, on day 18 of stay at HA, PRL levels were significantly increased (p less than 0.01) to 17.68 +/- 1.82 ng/ml and returned to initial SL values within seven days of return to SL. A significant decrease (p less than 0.01) in LH and testosterone was observed on seventh day of stay at HA and the decreased levels were maintained till day 18 of observations. Plasma testosterone returned to the initial SL values within a week of return to SL, whereas LH levels remained significantly lower (p less than 0.01). The FSH levels did not show any significant change during their stay at HA or after return to SL. These observations suggest that exposure to altitude is associated with hyperprolactenemia and an impaired pituitary gonadal function. The decreased levels of LH and testosterone at HA could either be due to hypoxic stress per se or secondary to altitude induced hyperprolactenemia.

Immunological response of chickens to Mycoplasma gallisepticum infection.

The cellular, humoral, and local immune responses of chickens to Mycoplasma gallisepticum infection were studied at weekly intervals for 10 weeks. A cellular response was indicated by significant leukocyte migration inhibition (LMI) was demonstrated as early as one week postinfection (PI), but the maximum LMI of 36.4% was observed at seven weeks PI. Induction of cellular response was further confirmed by positive-delayed type of hypersensitivity reaction, observed in all infected birds tested. The antibody response, as determined by the hemagglutination-inhibition (HI) test, was found to be provoked very early in infection, and the mean HI titer peaked seven weeks PI. A highly significant correlation (p less than 0.05) was found between LMI percentages and mean HI titers. In the infected chickens a significant elevation of mean serum immunoglobulin (Ig) G level was noted from the first week PI onwards; this correlated well with the rise of HI antibodies. There was no change in the serum IgA and IgM levels. A low level of M. gallisepticum-specific HI activity was detected in tracheal washings (TW) of infected birds from the third week PI onwards; the levels peaked six weeks PI. The IgA/IgG ratio in TW of infected chickens did not differ significantly from those of controls. The recovery of chickens as assessed by regression of lesions and disappearance of organisms from trachea coincided with peak LMI, maximum HI titers in serum and TW, and elevated levels of serum IgG.

Normal profile of immunoglobulins in sera and tracheal washings of chickens.

Concentration and distribution of the three immunoglobulins in the sera and tracheal washings of a chicken population was studied. The mean IgM, IgG and IgA concentrations in serum were 1.35, 5.09 and 0.31 mg/ml, respectively. The distribution of IgM and IgG in birds irrespective of age was almost normal whereas that of IgA was skewed. All the three immunoglobulins were present in tracheal washings but the level of IgM was barely detectable. The IgG was predominant in the tracheal washings but higher IgA : IgG ratio compared to that of serum indicated local IgA production in the chicken respiratory tract.