Biomedical subjects
Publications and source records attributed to G R Reddy.
Effect in vitro of propoxur on the specific activity of calcium stimulated ATPase and calcium uptake was studied in the rat brain synaptosomes. The data suggest that propoxur might disrupt the synaptic function by altering the calcium dependent ATP hydrolysis and calcium uptake in the central nervous system.
The kinetic analysis of succinate and lactate dehydrogenases (SDH and LDH) has been studied in muscle and liver of Bufo melanostictus under electropolarity treatment. Increased Vmax and decreased Km were observed both in liver and muscle under cathode electropolarity treatment whereas a reverse trend was noticed under anodal treatment. But the activation energy values (delta E) of both the enzymes decreased indicating enhanced catalytic efficiency under both cathodal and anodal treatments.
Kinetic study of succinate dehydrogenase (SDH) was studied in the brain of albino rat to elucidate the interaction of benthiocarb, an organocarbamate with oxidative metabolism. The significant decrease in maximal velocity (Vmax) without appreciable change in Michaelis-Menten constant (Km) indicates that benthiocarb did not affect or interfere with succinate oriented sites on the enzyme and the inhibition is of a classical non-competitive type.
Glutathione-S-transferase (GST), superoxide dismutase (SOD), Xanthine oxidase, selenium-dependent glutathione peroxidase (GPxI), catalase activities and malondialdehyde (MDA) content were determined in liver of three groups of exercised rats (E) viz., one day (E1), 10 days (E10) and 60 days (E60). GST, SOD and xanthine oxidase activities increased significantly with the increase in exercise period. Lipid peroxidation, expressed in terms of MDA formation, also increased in the liver of all the three groups. But catalase activity decreased significantly during exercise. Further, GPxI did not show any significant change in its activity in response to exercise. Our findings indicate that: 1) The significant increase in GST activity suggests their induction aimed at counteracting the oxidant stress induced during exercise; 2) The significant increase in xanthine oxidase and SOD activities indicates the generation of more superoxide anion radicals and their removal, respectively. 3) The significant reduction in catalase activity denotes the decreased formation of hydrogenperoxides during exercise; and 4) The pattern of changes in the activity level of GPxI indicate its least participation during exercise. However, in another way it is giving a scope for the involvement of GPxII associated with GST in the reduction of organic hydroperoxides. Further more, the relative increase in MDA is considered as the indicator of the rate of lipid peroxidation in the wake of exhaustive exercise.
Adult dogs with phosphofructokinase (PFK) deficiency have compensated hemolytic anemia, due to an absolute or functional deficiency of the muscle-type (M-type) subunit that normally accounts for a majority of total erythrocyte PFK activity in dogs. Potential effects of PFK deficiency on hematologic development were evaluated in dogs. Routine hematologic parameters were similar in normal and affected dogs when 1 day old, because all newborn dogs had erythrocyte PFK activities about three times that of normal adult dogs. Based on chromatographic separation of PFK isozymes and enzyme immunoprecipitation studies, the high PFK activity at birth was attributed to the predominance of the liver-type (L-type) subunit of PFK, which is negligible or absent in normal adult dog erythrocytes. Both total PFK activities and the amounts of L-type subunit present decreased dramatically during the first 6 to 8 weeks of life. The muscle-type subunit was negligible or absent at birth, but appeared and increased as the L-type decreased in normal dogs. These changes may result from the replacement of erythrocytes formed in the fetus with those formed after birth. A postnatal physiologic anemia developed to a similar degree in both affected and normal dogs because of decreases in both mean corpuscular volume and erythrocyte numbers. Reticulocyte counts were high in all dogs at birth and remained high in affected dogs, but decreased from 2 months of age onward in normal dogs. Erythrocyte 2,3-diphosphoglycerate (DPG) values were very low in all newborn pups and increased to values expected for adults in the respective groups by 2 to 4 weeks of age. A low 2,3-DPG concentration occurs in affected dogs because PFK deficiency inhibits glycolysis above the side shunt that forms 2,3-DPG.
The nucleotide sequence of a 2.86-kb cDNA clone containing the complete human muscle phosphofructokinase (PFK) protein-coding region was determined. It comprises 76 bp of 5'-untranslated sequence, 2340 bp encoding human muscle PFK polypeptide, and 399 bp of 3'-untranslated sequence plus a poly(A) tract. A retroviral vector was utilized to express the product of this coding sequence in mouse fibroblasts. The PFK-coding cDNA was shown to code for an enzymatically active polypeptide by immunoprecipitation analysis and DEAE-Sephadex A-25 chromatography.
Homoeotic appendages provide a system for the analysis of neural path-finding in which the appendage is mismatched with its segmented ganglion. Central projections of sensory neurons from homoeotic antennapedia regenerates induced by antennal amputation in the stick insect, Carausius morosus, are described. The majority of afferent axons project to the olfactory lobe as in the normal antennal nerve, but they do not give rise to compact glomeruli. Nor does the form of the projection resemble that of leg sensory nerves in thoracic ganglia. The projection of antennapedia regenerate neurons in Carausius resembles the antennapedia mutant of Drosophila except that some primary afferents bypass the olfactory lobe and take several courses through the brain, sometimes reaching distant contralateral areas. It appears that these wandering fibers, having bypassed the olfactory lobe, tend to follow established tracts and to arborize or to deviate at circumscribed synaptic areas. The behavioral evidence for sensory input from antennapedia regenerates is equivocal.
The effects in vivo and in vitro of benthiocarb, an organocarbamate, on acetylcholinesterase (AChE) activity and its recovery in vitro in the brain of the freshwater fish Sarotherodon mossambicus have been studied. Findings revealed that the specific activity of AChE was inhibited both in vivo and in vitro in a concentration-dependent manner. Of the different modulators tested, dexamethasone (0.72 mg), prednisolone (0.74 mg), testosterone (0.9 mg), and ADP (9.5 mg) were found to neutralize the inhibitory effect (IC50 = 0.30 microM) of benthiocarb on AChE.
Substrate kinetics of succinate dehydrogenase (EC 1.3.99.1) were studied in the brain of control and dieldrin-treated albino rats. Dieldrin inhibited the enzyme activity to various degrees and also altered the Michaelis-Menten constant (Km) of the enzyme. Activation energy values (delta E) were increased, suggesting decreased maximal velocity Vmax, and the high Km obtained for the enzyme also revealed decreased enzyme-substrate affinity and masking of active sites by dieldrin.
The glutathione oxidant defence system in leucocytes and erythrocytes of six Anaplasma marginale-infected calves was examined by assaying glutathione peroxidase (GSH-px), glutathione reductase (GSSG-R), reduced glutathione (GSH) and superoxide dismutase (SOD). In addition, GSH-S-transferase and arginase levels were measured in leucocytes. There was a significant decline in the activities of leucocyte GSH-px, GSSG-R and SOD in the post-patent period; whereas arginase activity rose significantly following the patent period of anaplasmosis. The activity of erythrocyte SOD declined in the post-patent stage. The infection also caused a decline in red cell GSH (P less than 0.05). The results suggest that the glutathione oxidant defence system of peripheral blood cells is significantly influenced by the Anaplasma infection.
Electropolarity treatment (0.8 V/DC/Cm) was given to the gastrocnemius muscle of Bufo melanostictus every day for 5 min. for 5 days, and kinetic study of succinate dehydrogenase (SDH) in muscle and liver was conducted with different effectors - sodium malonate, ethylene diamine tetra acetic acid (EDTA), calcium chloride (CACl2) and sodium citrate. Of the four modulators tested, the malonate and EDTA inhibited while sodium citrate and CACl2 activated the enzyme. The significance of the modulation in SDH activity to different extents was discussed.
Effects in vivo and in vitro of benthiocarb on developing rat brain Mg2+ and Ca2+-ATPases have been studied. Decreased activities of Mg2+ and Ca2+-ATPases suggests impairment in energy synthesis and utilization processes in developing CNS of rat during benthiocarb poisoning. Effects in vitro of benthiocarb on these enzymes revealed that Km (Michaelis-Menten Constant) of both the enzymes increased whereas Vmax (Maximal velocity) decreased significantly indicating mixed type of inhibition on these enzymes by benthiocarb.
Effect in vitro of benthiocarb, an organocarbamate herbicide on neonate rat (3 day old) brain was studied to understand the interaction of benthiocarb with Na+K+-ATPase. Na+K+-ATPase of the developing rat brain was selected as an index enzyme since alterations in the Na+K+-ATPase activity leads to neuronal dysfunction. The assay of Na+K+-ATPase in the presence of 1-8 mu moles of benthiocarb showed decreased activity and a concentration dependent inhibition of Na+K+-ATPase was noticed upto 7 mu moles of benthiocarb. Based on IC50 values (median concentration), 50% inhibition of the enzyme was observed with 5 mu moles of benthiocarb. Norepinephrine (NE) was selected to study the modulation of benthiocarb inhibited enzyme. Maximum increase (76.7%) of Na+K+-ATPase was noticed with 35 mu moles of NE and effective concentration (EC50) of NE which produced 50% activation of the enzyme was found to be 20 mu moles. This study suggests that NE acts as a protective agent in reversing the benthiocarb in vitro inhibited neonate rat brain Na+K+-ATPase.
Electropolarity treatment (0.8V/DC/Cm) was given to the gastrocnemius muscle of B. melanostictus every day for 5 min for 5 days. The glycogen content and aldolase activity levels increased and phosphorylase 'a' activity levels decreased on cathode treatment in muscle, liver and brain while an opposed trend was observed on anode treatment. The heart showed contrasting pattern under both cathode and anode electropolarity treatments.
Effects of repeated administration of benthiocarb on the nitrogen metabolism of hepatic and neuronal systems have been studied. Repeated benthiocarb treatment was associated with significant decrease in proteins with a concomitant increase in free amino acids (FAA) and specific activity levels of proteases suggesting impaired protein synthesis or elevated proteolysis. The glycogenic aminotransferases showed a significant elevation in both the tissues indicating high feeding of ketoacids into oxidative pathway for efficient operation of TCA cycle to combat energy crisis during induced benthiocarb stress. However, the activity levels of branched-chain aminotransferases decreased suggesting their reduced contribution of intermediates to TCA cycle. A comparative evaluation of the activity levels of ammonogenic enzymes, AMP deaminase, adenosine deaminase and glutamate dehydrogenase (GDH) indicated that ammonia was mostly contributed by nucleotide deamination rather than by oxidative deamination. GDH exhibited reduced activity due to low availability of glutamate. In accordance with increased levels of urea, the activity levels of arginase, a terminal enzyme of urea cycle was increased suggesting increased urea cycle operation in order to combat the increased ammonia content. As the presence of urea cycle in the brain is rather doubtful, the conversion of ammonia to glutamine for the synthesis of GABA is envisaged in brain whereas in liver, excess ammonia was converted to urea through ornithine-arginine reacting system. The increased glutaminase activity observed during benthiocarb intoxication is accounted for counteracting acidosis or maintenance of metabolic homeostasis. Arginase, a terminal enzyme of ornithine cycle showed increased activity denoting the efficient potentiality of tissues to avert ammonia toxicity. The changes observed in tissues of rat administered with benthiocarb reflects a shift in nitrogen metabolism for efficient mobilization of end products of protein catabolism.
Antimicrobial properties of some new carbonyl stabilized sulphonium ylides have been tested against two bacteria Staphylococcus aureus, Escherichia coli and two fungi Alternaria alternata and Curvularia lunata. The potent antifungal activity of these compounds suggest their practical applications in fungicidal formulations and other pharmacological preparations.
The functional significance of AMP deaminase and adenosine deaminase has been studied in hepatopancreas of active, aestivated and ganglionic extracts-administered snails. The activity levels of both enzymes decreased in aestivating snails. Active snails injected with ganglionic extracts of aestivated snails also showed decreased activity. Contrastingly, the hepatopancreas of aestivated snails when treated with ganglionic extracts of active snails showed increased specific activities of both enzymes. The decrease or increase in the specific activities varied with different ganglionic extracts and the significance of the same is discussed.
Benthiocarb effect on rat brain acetylcholinesterase (AChE) has been studied to know the toxic effects of benthiocarb on mammalian cholinergic systems. From the study, it has been observed that the inhibition of AChE activity increased with increase in treatment period which is attributed to the cumulative effects of benthiocarb on AChE activity. The kinetic study revealed that there is a slight increase in Km and a marked decrease in Vmax which accounts for the non-competitive inhibition of enzyme during benthiocarb intoxication.