Biomedical subjects
Publications and source records attributed to M M Reddy.
Lactate dehydrogenase (LDH), succinate dehydrogenase (SDH), aspartate aminotransferase (AAT), glutamate dehydrogenase (GDH), AMP deaminase, ornithine transcarbamylase (OTC), arginase and glutamine synthetase (GS) activities were increased in the kidney of the rat during repeated ethanol loading. The significance of these findings is discussed.
Natural killer cell activity of peripheral blood mononuclear cells against K562 myeloid cells was studied in 8 normal heterosexual men, 5 healthy homosexual men, and 11 homosexual men with acquired immune deficiency syndrome. The overall natural killer cell activity was lower in healthy homosexual men and in homosexual men with acquired immune deficiency syndrome. Peripheral blood mononuclear cells from four normal heterosexual men were preincubated overnight in complete medium supplemented with various concentrations of lectin-free interleukin 2 lacking interferon. Cells from these cultures exhibited a dose-dependent augmentation of natural killer cell activity. Peripheral blood mononuclear cells obtained from 8 normal heterosexuals, 5 healthy homosexuals, and 11 homosexual men with acquired immune deficiency syndrome were preincubated overnight in complete medium supplemented with 20% interleukin 2. Natural killer cell activity cultured in 20% interleukin 2 increased to 78.4 +/- 8.4 (mean +/- standard deviation) from 30.8 +/- 11.0 in normal heterosexual men, to 68.3 +/- 17.6 from 16.8 +/- 13.6 in healthy homosexual men and to 49.3 +/- 15.3 from 11.6 +/- 6.1 in homosexual men with acquired immune deficiency syndrome at a 100:1 effector/target cell ratio. These results suggest that interleukin 2 is capable of directly stimulating natural cell-mediated cytotoxicity. Consideration of the use of interleukin 2 as a potential therapeutic agent to modify immune responses in disorders such as acquired immune deficiency syndrome appears warranted.
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Natural Killer (NK) cell activity of peripheral blood mononuclear cells (PBMC) against K562 myeloid cells was studied in six normal heterosexual men and six patients with acquired immune deficiency syndrome (AIDS). The mean NK cell activity in six patients with AIDS was 28.74 +/- 6.82% (SEM) compared with 47.24 +/- 7.26% in six normal heterosexual men (p less than 0.10). PBMC obtained from these subjects were incubated overnight in complete medium alone, complete medium supplemented with interferon-alpha 2 (IFN-alpha 2), complete medium supplemented with interleukin-2 (IL-2), and complete medium supplemented with both IFN-alpha 2 and IL-2. Incubation of PBMC with IFN-alpha 2 enhanced the NK cell activity significantly (73.07 +/- 4.22%, p less than 0.025) in normal heterosexual men, but not in patients with AIDS (38.22 +/- 7.10%, p greater than 0.05). In contrast, IL-2 significantly enhanced NK cell activity in both patients with AIDS (57.16 +/- 8.4%, p less than 0.05) and normal heterosexual men (71.58 +/- 5.87%, p less than 0.05). When PBMC from both groups of subjects were incubated with both IFN-alpha 2 and IL-2, the NK cell activity increased to levels higher than those seen with either IFN-alpha 2 or IL-2 alone. These results suggest that IL-2 is capable of augmenting in vitro NK cell-mediated cytotoxicity with cells from AIDS patients.
Three different regions of the vertebrate central nervous system maintained in vitro (frog spinal cord, guinea pig olfactory cortex and hippocampus) have been used to investigate how Li+ influences membrane potential, membrane resistance, action potentials, synaptic potentials and the transmembrane K+-distribution of neurons and glial cells. In view of the therapeutic action of Li+ in manic-depressive disease, a special effort was made to determine the threshold concentration for the actions of Li+ on the parameters described above. It was observed that Li+ induced a membrane depolarization of both neurons and glial cells, a decrease of action potential amplitudes, a facilitation of monosynaptic excitatory postsynaptic potentials and a depression of polysynaptic reflexes. The membrane resistance of neurons was not altered. Li+ also induced an elevation of the free extracellular potassium concentration and a decrease of the free intracellular potassium concentration. Furthermore, in the presence of Li+ a slowing of the recovery of the membrane potential of neurons and glial cells, and of the extracellular potassium concentration after repetitive synaptic stimulation was observed. The threshold concentrations for the effects of Li+ were below 5 mmol/l in the frog spinal cord and below 2 mmol/l in the guinea pig olfactory cortex and hippocampus. The basic mechanism underlying the action of Li+ may be an interaction with the transport-function of the Na+/K+ pump.
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Lithium sensitive microelectrodes were used to investigate the transmembrane distribution of lithium ions (Li+) in motoneurons of the isolated frog spinal cord. After addition of 5 mmol.1(-1) LiCl to the bathing solution the extracellular diffusion of Li+ was measured. At a depth of 500 micrometers, about 60 min elapsed before the extracellular Li+ concentration approached that of the bathing solution. Intracellular measurements revealed that Li+ started to enter the cells soon after reaching the motoneuron pool and after up to 120 min superfusion, an intra - to extracellular concentration ratio of about 0.7 was obtained. The resting membrane potential and height of antidromically evoked action potentials were not altered by 5 mmol.1(-1) Li+.
A post-tetanic membrane hyperpolarization following repetitive neuronal activity is a commonly observed phenomenon in the isolated frog spinal cord as well as in neurons of other nervous tissues. We have now used double-barrelled Na+- and K+-ion-sensitive microelectrodes to measure the intracellular Na+- and K+-concentrations and also the extracellular K+-concentration of lumbar spinal motoneurons during and after repetitive stimulation of a dorsal root. The results show that the post-tetanic membrane hyperpolarization occurred at a time when the intracellular [Na+] reached its maximal value, intracellular [K+] had its lowest level and extracellular [K+] was still elevated. The hyperpolarization was blocked by ouabain and reduced by Li+. These data support the previous suggestion that an electrogenic Na+/K+ pump mode may be the mechanism underlying the post-tetanic membrane hyperpolarization.
Adsorption of [35S]methionine-labeled reovirus by 30 dry soils, minerals, and finely ground rocks suspended in synthetic freshwater at pH 7 was investigated to determine the conditions necessary for optimum virus removal during land application of wastewaters. All of the minerals and soils studied were excellent adsorbents of reovirus, with greater than 99% of the virus adsorbed after 1 h at 4 degrees C. Thereafter, virus remaining in suspension was significantly inactivated, and within 24 h a three to five log10 reduction in titer occurred. The presence of divalent cations, i.e., Ca2+ and Mg2+, in synthetic freshwater enhanced removal, whereas soluble organic matter decreased the amount of virus adsorbed in secondary effluent. The amount of virus adsorbed by these substrates was inversely correlated with the amount of organic matter, capacity to adsorb cationic polyelectrolyte, and electrophoretic mobility. Adsorption increased with increasing available surface area, as suspended infectivity was reduced further by the more finely divided substrates. However, the organic content of the soils reduced the level of infectious virus adsorbed below that expected from surface area measurements alone. The inverse correlation between virus adsorption and substrate capacity for cationic polyelectrolyte indicates that the adsorption of infectious reovirus particles is predominately a charged colloidal particle-charged surface interaction. Thus, adsorption of polyelectrolyte may be useful in predicting the fate of viruses during land application of sewage effluents and sludges.
Intraperitoneal injection of 0.15 M LiCl (2% body weight) to anaesthetized rats elicited, after a 6 min latency, discharge of about 50% units i basolateral amygdala (n = 27). The activation lasted for 15 min on the average. Cortical neurones were not affected by the LiCl injection. It is suggested that the amygdalar reaction to LiCl administration may account for the association of the gustatory trace with the visceral signals of poisoning which mediates acquisition of conditioned taste aversion under anaesthesia.
The adsorption of radiolabeled infectious poliovirus type 2 by 34 well-defined soils and mineral substrates was analyzed in a synthetic freshwater medium containing 1 mM CaCl(2) and 1.25 mM NaHCO(3) at pH 7. In a model system, adsorption of poliovirus by Ottawa sand was rapid and reached equilibrium within 1 h at 4 degrees C. Near saturation, the adsorption could be described by the Langmuir equation; the apparent surface saturation was 2.5 x 10(6) plaque-forming units of poliovirus per mg of Ottawa sand. At low surface coverage, adsorption was described by the Freundlich equation. The soils and minerals used ranged from acidic to basic and from high in organic content to organic free. The available negative surface charge on each substrate was measured by the adsorption of a cationic polyelectrolyte, polydiallyldimethylammonium chloride. Most of the substrates adsorbed more than 95% of the virus. In general, soils, in comparison with minerals, were weak adsorbents. Among the soils, muck and Genesee silt loam were the poorest adsorbents; among the minerals, montmorillonite, glauconite, and bituminous shale were the least effective. The most effective adsorbents were magnetite sand and hematite, which are predominantly oxides of iron. Correlation coefficients for substrate properties and virus adsorption revealed that the elemental composition of the adsorbents had little effect on poliovirus uptake. Substrate surface area and pH, by themselves, were not significantly correlated with poliovirus uptake. A strong negative correlation was found between poliovirus adsorption and both the contents of organic matter and the available negative surface charge on the substrates as determined by their capacities for adsorbing the cationic polyelectrolyte, polydiallyldimethylammonium chloride.
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Waves of spreading depression (SD) no not penetrate into an electrically stimulated (10 Hz, 0.05 msec, 20-30 V) cortical area of rats. The blockade develops slowly and is proportional to the (K+)e increase in the stimulated cortex. After cessation of stimulation, (K+)e returns to the resting level within 20-30 sec, but the SD blockade continues for 2-3 min. It is suggested that the stimulation induced activation of a metabolic pump disrupts the autoregenerative mechanism of SD propagation by enhancing K+ reabsorption into neurons.
Micronuclei frequency and percent of chromosome breaks increases significantly in adults whose thymus glands were irradiated in infancy and after irradiation of cancer patients.
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T, B and "Null" lymphocytes were determined in the peripheral blood of 98 adults, 26 of them were between 20 to 40 years of age and 72 between 60 to 96 years of age. The total number of lymphocytes were about the same in both groups. The percent and absolute number of T cells decreased significantly in the aged. Although the percent of B lymphocytes increased with age, the absolute number of B lymphocytes remained about the same.