Biomedical subjects
Publications and source records attributed to A Namasivayam.
Wistar strain albino rats of either sex were subjected to acute noise stress (3000 Hz at > 97 dB) for 30 minutes. Carbon clearance test was conducted in noise stressed animals immediately after the stress period. Significant (P < 0.001) increase of the clearance constant K was observed in stressed animals compared to the controls, indicating increased phagocytic activity of the reticuloendothelial system.
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Rats with bilateral electrolytic ventral hippocampal formation (VHF) lesion show a significantly (p less than 0.001) enhanced migration of leucocytes in the presence of antigen. Immunization in these animals enhances (p less than 0.001) the leucocyte migration and presents a significant decrease in footpad thickness. Antibody titre (p less than 0.001) and plaque-forming cells (p less than 0.02) also show a significant decrease when compared with sham-lesion-immunized animals and control-immunized animals. These data indicate the influence of VHF in modulating the specific immunity.
The effect of acute heat stress on certain immunological parameters were studied in male albino rats. The test rats were exposed to an ambient temperature of 40 degrees celsius for 30 minutes and sacrificed immediately. Total WBC count, Differential count, Phagocytic index, NBT reduction, organ weight body weight ratio of spleen, thymus, and popliteal lymph nodes, and soluble immune complex levels were measured in control group and the heat stressed animals. The heat stressed animals show decrease in total WBC count, and neutrophilia, eosinophilia, and lymphocytopenia. The phagocytic index showed a significant increase whereas the avidity index showed a decrease from the control value. NBT reduction was also significant. The soluble immune complex level was not altered. The heat stressed animals showed a decrease in the thymus and spleen weight/body weight ratio while the lymph node/body weight ratio showed an increase compared to the control animals.
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A simple program for drawing Bar graphs on IBM Personal computers is described here. This program is written in BASIC language and is user friendly. The program allows the operator to plot the bars with standard error, adjust the spacing between the bars and save the 'bar in a floppy disk. Legend can also be added at appropriate places in the graph. In the graphic mode, a hard copy can be obtained from a dot matrix printer using print screen command.
Bilateral electrical lesion at ventral hippocampal formation (VHF) did not affect some aspects of nonspecific immunity like total W.B.C. count, percentage of cells in differential count, their absolute count (lymphocyte and neutrophils) and neutrophil functions. The changes observed are due to non-specific craniocerebral trauma as the sham operated animals also showed a similar pattern of response. However the lesion at VHF increases the spleen cell count significantly whereas immunization in these animals decreases the spleen cell count. The thymus weight/body weight ratio also decreases in these animals. Our study confirms the neuroimmuno modulation and the influence of VHF on certain nonspecific immune parameters.
The effect of subacute cold swimming stress on the immune system of albino rats was investigated. Subacute cold stressed animals showed an increase in total WBC count, eosinophils and basophils. Phagocytic index and avidity index were also increased indicating hyperactive phagocytic process. On the other hand NBT reduction and soluble immune complex levels decreased significantly in stressed animals. There were no significant changes in the weight of the lymphoid organs.
Changes in monoamines were studied in discrete areas of brain with varying dose of isopropanol. Acute administration of isopropanol (0.463 g/kg, 0.925 g/kg and 1.85 g/kg) decreased dopamine level in hypothalamus, pons medulla and cerebral cortex and whereas it was increased in striatum and cerebellum. Noradrenaline level was reduced in all the brain areas studied. Adrenaline level was increased in hypothalamus, striatum, midbrain and pons medulla, and decreased in hippocampus and cerebral cortex. Serotonin level was increased in hypothalamus, midbrain, pons-medulla and cerebral cortex, and decreased in striatum and hippocampus. These changes were dose-dependent. It is concluded that isopropanol causes changes in brain monoamine content that this effect is not the same in all the regions of the brain.
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The variations in brain monoamine levels after methanol administration were studied in discrete areas of rat brain. Acute methanol administration (2 g/kg and 4 g/kg) significantly decreased Dopamine (DA) level in striatum and increased it in hypothalamus. Nor-Epinephrine (NE) and Epinephrine (E) levels were reduced in most of the areas studied. Serotonin (5HT) level was increased in hypothalamus, midbrain and cortex with corresponding increase in 5 Hydroxy Indole Acetic Acid (5 HIAA) level. It was concluded that central monoaminergic neurons were specifically influenced either directly or indirectly after methanol administration and that the effect of methanol differed according to the brain area and its action on different monoaminergic systems were quite different.
This paper suggests that like ethanol, methanol also produces certain changes in the steady state level of monoamines in hypothalamus and striatum of albino rats. Though, the toxic manifestations of methanol are attributed to the metabolic end product of methanol viz. formic acid by several workers, we report here that the methanol-induced brain monoamine changes, at least, could be attributed to the direct action of methanol rather than to its metabolic end products like formaldehyde or formate. Studies in the steady state level of rat brain monoamines have shown that after methanol administration (3 g/kg), there is severe depletion of dopamine level in striatum but a significant increase in the level of dopamine, serotonin and 5-hydroxy indole acetic acid in hypothalamus. At the same time, norepinephrine and epinephrine levels are reduced in hypothalamus as well as in striatum. These effects do not seem to be induced by metabolic acidosis. The changes in monoamine levels are very well correlated with the blood and brain level of methanol as evidenced by maintaining a higher methanol level either by simultaneous administration of ethanol or by blocking methanol metabolism by pretreatment with 4-methyl pyrazole and 3-amino-1,2,4-triazole. It is thus postulated that monoamine changes induced by methanol appear to be the direct effect of methanol per se on the monoaminergic neuronal membranes.
Alteration in the steady state level of brain biogenic amines produced by methanol differ considerably in rats when compared to the effects produced by ethanol. When ethanol and methanol were administered simultaneously in identical concentration, the effects produced by methanol were much more pronounced in the presence of ethanol. This could be attributed to the delay in the metabolism of methanol as ethanol competes with methanol for alcohol dehydrogenase enzyme activity. Hence, it is presumed that the effects produced by methanol seem to be primarily due to the direct action of methanol itself and not due to metabolic end products of methanol. It is also inferred that if methanol per se is going to produce any permanent damage in the central nervous system due to abnormal neurotransmitter behaviour, they cannot be prevented by treatment with ethanol.
Albino rats were exposed to isolation, haemorrhagic, and psychic stress. The myocardial norepinephrine (NE), epinephrine (E), dopamine (DA), 5-hydroxytryptamine (5HT) and 5-hydroxy indole acetic acid (5HIAA) were quantitatively estimated at varying periods of time. The results indicate that 5HT, E, and DA are the common denominators in various types of stress and show similar qualitative changes in all the stresses studied whereas norepinephrine shows both quantitative and qualitative differences in the various stresses studied indicating thereby a differential modulatory mechanisms operating for the release of noradrenaline.
Alterations in the steady state level of rat brain biogenic amines - dopamine, nor-epinephrine, epinephrine, serotonin and 5-hydroxy indole acetic acid, in response to intraperitoneal administration of methanol (3g/kg b.w.) were studied in discrete areas of the rat brain. The monoamine changes induced by methanol were quite different from those induced by ethanol consumption. They were also region-specific; hypothalamus being more vulnerable for methanol-induced monoamine changes. The effects produced by methanol were correlated with the blood and brain level of methanol at the given time, suggesting that the effects were dependent upon the local concentration of methanol in different brain regions. Acidosis induced by ammonium chloride and sodium formate administration did not alter the monoamine levels and therefore, the effects of methanol were not possibly due to acidosis. Blocking or delaying the metabolism of methanol either by 4-Methyl Pyrazole and 3-Amino 1,2,4-Triazole or by simultaneous administration of ethanol resulted in the potentiation of methanol effect. Therefore, it was concluded that methanol induced changes in brain biogenic amines were due to methanol per se and not due to metabolic end products viz. formaldehyde or formic acid.
The effects of low power He-Ne laser of 7 milliwatt power on certain immuno-haematological parameters were studied using fresh human blood samples. The parameters studied include electrophoretic mobility of haemoglobin, quantification of immunoglobulins, soluble immune complex levels, blood grouping, Rh typing and neutrophil function tests. Our results show that there is no significant change in the parameters studied after laser irradiation for 60 minutes except changes in the electrophoretic mobility of haemoglobin. In addition laser exposure causes haemolysis in all the samples examined.
The effects of acute auditory stress on certain biochemical parameters like blood corticosterone, total cholesterol, triglyceride, Serum glutamic pyruvic transaminase (SGPT) and Serum glutamic oxaloacetic transaminase (SGOT) were studied in albino rats. A significant increase was observed in the blood level of corticosterone, total cholesterol, SGOT and SGPT while a marked reduction was noticed in the Sr. triglyceride level. These data indicate that noise could be a potent stressor and cause disturbances in the biochemical parameters of the body. It is presumed that most of the effects are indirect, being manifested through the activation of autonomic nervous system which liberates catecholamines and hypothalamo pituitary adrenal axis responsible for the liberation of corticosteroids.