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Biomedical subjects

R K Saxena

Publications and source records attributed to R K Saxena.

At least 109 records · Page 6Linked to original sources
PubMed1981

Autonomic responses of high-altitude natives during sojourn at plains and on return to altitude.

The study was conducted on 20 high-altitude natives (HAN-I) 19-32 years old, to evaluate the changes in autonomic responses during their 2-months sojourn on the plains, and on return to high altitude (HA). The autonomic indices measured were heart rate HR), blood pressure (BP), oral temperature (Tor), mean skin temperature (Tsk), respiratory rate (RR), Cold pressor response (CPR), HR-response to tilt at 70 degree, and alpha index (AI) of EEG (occipital). These indices were recorded periodically during the 2 months of their stay on the plains, and thereafter on return to altitude for a period of 1 month. For comparison, the same responses were studied on 10 lowlanders (LL) on the plains and on induction to HA along with HAN-I. The study was repeated at altitude, once on 10 HAN who had never been to the plains (HAN-II) and on 10 acclimatised lowlanders. The results suggest that the relative parasympathetic dominance observed in natives at HA showed a gradual decrease during their sojourn on the plains, probably due to the elevation in sympathetic activity. On return to high altitude, they showed further increase in sympathetic excitation, as observed in LL on acute induction, but the magnitude of this response was less in natives. However, they showed a trend to faster return of autonomic responses to their initial level compared to LL.

Adaptation, Physiological↗
PubMed1980

Monoclonal anti thy 1.2 antibodies from hybridoma HO13-4 do not react with mouse natural killer cells.

The susceptibility of NK cells and immune cytotoxic T-cells to treatment with (a) monoclonal anti thy 1.2 antibodies from hybridoma HO13-4, (b) rabbit anti-mouse T-cell antiserum and (c) gamma globulins prepared from AKR/J anti C3H/HeJ antiserum was studied in the presence of rabbit complement. Monoclonal anti thy 1.2 antibody treatment completely abolished the cytotoxic activity of immune T-cells derived from C57BL/6J mice (H-2b) immunized with (C57BL/6J x DBA/2)F1 spleen cells (H-2bd) against P815 (H-2d) target cells. The same treatment had no significant effect on the NK activity of spleen cells from unimmunized mice against YAC target cells. Rabbit anti-mouse T-cell and mouse anti theta antisera also abrogated completely the immune T cell activity of spleen cells. This treatment however also resulted in a partial loss of NK activity. These results indicate that conventional anti theta antisera contain antibodies which recognize antigenic specificities on T-cells as well as on a population of NK cells. The cross reactivity is not a result of thy 1.2 antigen expression on NK cells and T-cells as recognized by the monoclonal antibodies. The specificity recognized by the monoclonal antibody (HO13-4) is only expressed on T-cells.

Animals↗
PubMed1979

Modulation of natural cytotoxicity by alloantibodies. I. Alloantisera enhancement of cytotoxicity of mouse spleen cells toward a human myeloid cell line.

Natural killer activity of spleen cells obtained from different strains of mice against the human myeloid leukemia cell line, K562, and two mouse cell lines P815 and L1210 was measured by using the 4-hr chromium release assay. The level of cytotoxic activity of spleen cells against the K562 target was usually less than 4% lysis. However, treatment of the spleen cells with a specific anti-H-2 antiserum resulted in a dose-dependent augmentation of the degree of lysis of K562 cells. The augmentation of cytotoxic activity could be obtained by pretreatment of the spleen cells with antisera or by directly adding the antisera to the cytotox-incubation medium. Anti-thy-1 and anti-immunoglobulin antisera had no enhancing effect under similar conditions. The specific alloantisera-treated spleen cells did not show any increase in cytotoxicity against P815 and L1210 target cells. Spleen cells responsible for the alloantiserum-mediated augmentation of cytotoxicity against K562 cells appear to be different from T or B cells as indicated by their resistance to anti-thy-1 and complement treatment and lack of adherence to nylon wool columns.

Animals↗
PubMed1978

Changes in EEG pattern during acclimatization to high altitude (3500 m) in man.

This study was conducted on 30 healthy soldiers to observe EEG changes during acclimatization to high altitude. Of these subjects, 10 were lowlanders (LL), 10 were acclimatized low landers (AL), and 10 10 were high-altitude natives (HAN). The EEG was recorded by the 10-20 international system of electrode placement in LL at sea level (SL) during rest and hyperventilation (HV). Then they were air-lifted to an altitude of 3500 m where periodic recordings of EEG were made for 4 weeks. For comparison, the altitude recordings were also made in AL and HAN. The quantitative analysis of EEG (occipital) was done to determine alpha index (AI) and average amplitude. The mean AI was 25.5% at SL in LL, which changed to 45.7%, 15.8%, 28.0%, 30.3%, and 33.2% on days 2, 7, 14, 21, and 28, respectively. The average amplitude was 17.3 microV at SL, which changed to 23.3 microV, 11.8 microV, 16.2 microV, 17.3 microV, and 19.8 microV on days 2, 7, 14, 21, and 28, respectively. In two subjects, spiking was seen along with the desynchronized pattern of EEG on days 7 and 14. The AI and average amplitude of AL and HAN were significantly more than those of LL. The magnitude of buildup during HV was greater at altitude. These results indicate that there is cerebral cortical depression in the initial phase of induction which changes to cortical desyncronization in the latter part of the first week of induction. During acclimatization, there is gradual buildup of EEG waves, as observed in AL and HAN.

Acclimatization↗