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Biomedical subjects

K S Rao

Publications and source records attributed to K S Rao.

At least 19 recordsLinked to original sources
PubMed1995

Modulations in antioxidant enzymes in different tissues of marine bivalve Perna viridis during heavy metal exposure.

Lipid peroxidation induced by metals at sub-lethal levels, alter physiological and biochemical characteristics of biological systems. To counter the detrimental effects of the prooxidant activity of metals, a group of antioxidant enzyme systems function in the organisms. The present study was performed to investigate into the lipid peroxidation product formation due to the exposure to effects of the metals namely aluminium, lead and cadmium at sub-lethal concentrations and the biological response through protective antioxidant enzyme activity in the marine mussels, Perna viridis Lin.. This organism is a known bioindicator and bioconcentrator of metals in the environment. The results of the present study were: (a) accumulation of lead showed a definite linear increase during the period of exposure whereas aluminium and cadmium showed fluctuations. Mantle and gill tissues showed greater accumulation of metals when compared to digestive gland; (b) lead and aluminium induced lipid peroxidation was greater in tissues than the peroxidation induced by cadmium. Cadmium induced peroxidation was observed only after the day 7 of the exposure; (c) anti-oxidant enzymes activity levels were significantly higher in digestive gland and mantle than gills; (d) mantle was observed to significantly contribute to the organismal response to lipid peroxidation as indicated by high activity levels of anti-oxidant enzymes.

Aluminum↗
PubMed1995

Modulation in acetylcholinesterase of rat brain by pyrethroids in vivo and an in vitro kinetic study.

The modulation of acetylcholinesterase (AChE) of rat brain by two pyrethroids--permethrin (PM) and cypermethrin (CPM)--was studied both in vivo and in vitro. PM inhibited AChE activity in all regions of the rat brain (cerebral cortex, cerebellum, corpora striata, brain-stem, hippocampus, and hypothalamus) at 4, 8, and 12 h after gastric intubation, whereas CPM elevated the enzyme activity in vivo. Substrate-dependent enzyme kinetic studies have shown that PM and CPM behave as mixed-type inhibitors, as evidenced by alterations in both Michaelis-Menten constant (Km) and maximal velocity (Vmax) values. This indicates that both PM and CPM and substrate acetylcholine interact at hydrophobic subsites and may be able to bind simultaneously to the enzyme.

Acetylcholinesterase↗
PubMed1995

Aluminium leaching from utensils--a kinetic study.

Aluminium leaching from low quality (Al-Pb alloy) and high quality (Al-Mn alloy) utensils by water has been studied under different conditions of pH, boiling time and NaF concentrations. High fluoride concentration and low pH were found to enhance the leaching of Al more from low quality utensils than from high quality utensils.

Aluminum↗
PubMed1994

Purification and characterization of a deoxy-ribonuclease acting on native and UV irradiated DNA from young and aging rat brain.

A deoxyribonuclease has been purified to electrophoretic homogeneity from young and old rat brain. The enzyme is an endonuclease, with an optimum pH 5.0. Divalent cations are not needed for the activity. The DNase showed highest activity towards Native DNA either as such or UV irradiated with little activity on denatured DNA, apurinic DNA or DNA pretreated with mitomycin C or actinomycin D. The enzyme hydrolyzes double stranded poly (dA-dT).(dA-dT) but not other homologous or heterologous synthetic polynucleotides. The enzyme does not excise pyrimidine dimers preferentially but acts at a site away from the dimer. The DNase was partially purified from nuclei also and both the nuclear and extra nuclear enzymes showed similar properties. The specific activity of brain DNase decreases markedly with age. DNase preparations from both young and old rats showed similar apparent molecular weight (62KD) and many other properties like elution profiles and the N-terminal amino acid. However the old enzyme was more susceptible to temperature and proteolytic digestion. These results are taken to indicate a possible role for this enzyme in recognizing conformational distortions in DNA and that altered molecules of this enzyme accumulate in aging brain.

Aging↗
PubMed1994

Effect of aluminium (Al) on brain mitochondrial monoamine oxidase-A (MAO-A) activity--an in vitro kinetic study.

Effect of aluminium (Al) on rat brain mitochondrial monoamine oxidase-A (MAO-A) was studied in vitro at three different pH (4.0, 7.4 and 9.0) values. The results have shown that Al is a non-competitive inhibitor for MAO-A. The data also showed that MAO-A inhibition by Al varies with free Al3+ concentration and different forms of Al under different pH conditions. Al altered the maximum velocity (Vmax) of MAO-A but did not affect substrate-enzyme affinity (Km). Al formed a strong chelation with the substrate (Kynuramine) (1:1).

Aluminum Compounds↗
PubMed1994

The characterization of aluminium--alanine complex.

The potentiometric titration curves and computer modelling studies indicated that aluminium complexes with alanine at -C00- moiety and also altered the proton affinity at +NH3 and -CH3 moiety. 27Al NMR spectra broadening also confirmed the interaction.

Alanine↗
PubMed1994

Interaction of transport resistances with biochemical reaction in packed-bed solid-state fermentors: effect of temperature gradients.

In solid-state fermentation, the interaction of transport phenomena with biochemical reactions has a considerable effect on the productivity of the bioreactor. Previous work on solid-state fermentation in tray fermentors in our laboratory indicated that heat transfer resistance results in steep temperature gradients within the solid substrate bed, which in turn adversely affect the biochemical reaction and enzyme activity. This problem of heat accumulation during the course of fermentation has been alleviated to a considerable extent using a packed-column bioreactor with forced aeration in the present work. Experimental studies were conducted in a packed-column bioreactor utilizing wheat bran as substrate and the fungus Aspergillus niger CFTRI 1105 for the production of the enzyme amyloglucosidase. The enzyme activities were estimated and temperatures were recorded at different bed heights, for different air flow rates during the course of fermentation. The results indicated that the temperature gradients caused by heat transfer resistances were reduced considerably with corresponding increases in enzyme activity.

Aspergillus niger↗
PubMed1994

On the 'active' molecules of DNA-polymerase beta in aging rat brain.

DNA polymerase beta, a 38kD protein is essentially considered to be a repair enzyme at least with respect to some forms of DNA damage. Through northern and western blotting, it was found that mRNA and immunologically reactive molecules of DNA-polymerase beta are reduced by 30% and 20% respectively in old rat brain as compared to the young. However, activity gel assay and immunotitration revealed a 50% reduction in the activity in old brain. These data are taken to indicate accumulation of catalytically inactive molecules of DNA-polymerase beta in rat brain with age.

Aging↗
PubMed1993

Interaction of transport resistances with biochemical reaction in packed bed solid state fermenters: the effect of gaseous concentration gradients.

Mass transfer plays an important role in solid state fermentation (SSF) systems. Earlier work on SSF in tray bioreactors indicated that steep gaseous concentration gradients developed within the substrate bed, owing to mass transfer resistances, which may adversely affect the bioreactor performance. For all practical purposes these gradients have been eliminated using a packed bed column bioreactor with forced aeration. Gaseous concentrations (oxygen and carbon dioxide) and enzyme activities were measured at various bed heights for various air flow rates during the course of fermentation. The results indicated that concentration gradients were decreased effectively by increasing air flow rate. For example, the actual oxygen and carbon dioxide concentration gradients reduced from 0.07% (v/v) cm-1 and 0.023% (v/v) cm-1 to 0.007% (v/v) cm-1 and 0.0032% (v/v) cm-1 respectively when the air flow rate was increased from 5 dm3 min-1 to 25 dm3 min-1. This resulted in an overall improvement in the performance of the bioreactor in terms of enzyme production.

Aspergillus niger↗
PubMed1992

Evidence for a hydroxy-aluminium polymer (Al13) in synaptosomes.

The presence of the hydroxy-aluminium polymer (Al13-(OH)24O4(H2O)12(7+)) was noticed inside synaptosomes when synaptosomes were incubated with Al(NO3)3 at neutral pH values. Dysprosium nitrate (Dy(NO3)3)--a shift reagent--facilities the identification of the Al13 species distinctly inside the synaptosomes. 27Al NMR was used as a tool to detect the Al13 complex inside and outside the synaptosomes.

Aluminum↗
PubMed1992

DNA damage and repair in brain: relationship to aging.

The usefulness of conducting DNA damage and repair studies in a postmitotic tissue like brain is emphasized. We review studies that use brain as a tissue to test the validity of the DNA damage and repair hypothesis of aging. As far as the accumulation of age dependent DNA damage is concerned, the data appear to overwhelmingly support the hypothesis. However, attempts to demonstrate a decline in DNA repair capacity as a function of age are conflicting and equally divided. Possible reasons for this discrepancy are discussed. It is suggested that assessment of the repair capacity of neurons with respect to a specific type of damage in a specific gene might yield more definitive answers regarding the role of DNA repair potential in the aging process and as a longevity assurance system.

Aging↗
PubMed1992

Lack of smooth muscle in the small pulmonary arteries of the native Ladakhi. Is the Himalayan highlander adapted?

Chronic hypobaric hypoxia induces a mild degree of pulmonary arterial hypertension with structural alterations in the peripheral portions of the pulmonary arterial tree of the native Andean highlanders. On the other hand, animals indigenous to high altitude do not show these changes and are adapted to hypobaric hypoxia. The small pulmonary arteries of seven native Himalayan highlanders were examined at autopsy and found to be thin-walled with no medial hypertrophy of the muscular pulmonary arteries or muscularization of the arterioles. These findings suggest that the Himalayan highlanders may be adapted to hypobaric hypoxia.

Adaptation, Physiological↗
PubMed1992

Effect of aluminium (Al) on the brain cells of the rat.

The data on binding of Al to different brain cells, namely astrocytes, neuronal cells and synaptosomes, indicated that Al interacts more with astrocytes than with neuronal cells and synaptosomes. This was confirmed by broadening of the linewidth at half height (v 1/2 Hz) of the Al peak, and also by the extent of inhibition of membrane-bound Na+,K(+)-ATPase activity.

Aluminum↗
PubMed1992

Studies on the role of iron binding ligands and the intestinal brush border receptors in iron absorption.

With a view to identifying ligands that could be used as promoters of iron absorption, the affinity of a number of iron chelating agents and the efficiency with which they can donate iron to the brush border receptors has been studied. A number of organic and inorganic compounds were found to chelate iron and keep it soluble at pH 7.5 of the intestinal lumen. This ligand-bound iron was taken up by the intestinal brush border receptors with varying degree of efficiency; ascorbic acid being the most effective and EDTA and citrate the least effective in donating the chelated iron to the receptors. Several polyphosphate compounds, used as food additives, chelated iron and kept it in solution but showed moderate potency for donating iron to the receptors.

Animals↗
PubMed1991

Structural stability of lipase from wheat germ in alkaline pH.

The present investigation shows the effect of alkaline pH on the structure-function relationship of lipase from wheat germ. There is a 70% decrease in lipase activity at pH 10.0, which decreases to 93% at pH 12.0 as compared to neutral pH activity (Rajendran et al. 1990). This change is shown to be as a result of loss of alpha-helical structure with a concomitant increase in aperiodic structure. The results with fluorescence spectra and tyrosyl ionization indicate gradual exposure of aromatic side chains of tyrosine and tryptophan to the bulk solvent along with the structural changes. The enzyme is in an extended form at alkaline pH with a volume change of - 1300 ml mol as also indicated by increase in reduced viscosity to 12.5 ml g and significant decrease in sedimentation coefficient. The kinetics of the reaction points to a cooperative pseudo first-order reaction as determined by stopped-flow kinetic analysis in the ultraviolet region. The inactivation mechanism appears to follow a two-step mechanism of a fast and a slow reaction.

Chemical Phenomena↗
PubMed1991

Ultraviolet light-induced unscheduled DNA-synthesis in isolated neurons of rat brain of different ages.

DNA-repair capacity, by incorporation in vitro of [3H]thymidine into DNA of isolated neuronal cells and splenic lymphocytes of rat was studied as a function of age. The incubations were carried out both in the presence and absence of hydroxyurea (HU), a known inhibitor of replicative DNA synthesis. The results indicate that neurons, unlike lymphocytes, obtained from adult and old animals offer a good model system to measure the DNA-repair process without any possible interference of DNA replicative synthesis. Further, the 'spontaneous' DNA repair by unscheduled DNA synthesis (UDS) in old neurons remained unchanged as compared to the adult level. However, the response of aging neurons, in contrast to that of young and adult neurons or of lymphocytes of any age, to a mutagenic challenge like UV light is limited. It is suggested that this lack of responsive DNA-repair against a given damage may lead to a general metabolic deterioration and senescence.

Aging↗
PubMed1991

Surgical correction of claw fingers in Hansen's disease by palmar plate shortening and pulley advancement.

A simple technique has been used to correct the clawing of fingers in patients with Hansen's disease. The distal part of the palmar plate is excised and the remaining portion is advanced and sutured with a single horizontal mattress suture to prevent hyperextension of the metacarpophalangeal joint. A pulley advancement is also done. One hundred five claw hands were corrected in 99 patients from December 1985 to September 1988. Follow-up period varied from 6 months to 3 1/2 years. The results were assessed for correction of deformity, power grip, motion, and function. Out of 94 hands that were followed up after operation, power grip remained static in most cases. Correction of deformity was satisfactory in 85 hands, motion and function of the fingers were satisfactory in 63 hands, and correction of the clawing was statistically significant in two fingers (p less than 0.01).

Adult↗