Biomedical subjects

V Manojkumar

Publications and source records attributed to V Manojkumar.

6 recordsLinked to original sources

PubMed2000

Tryptophan and tyrosine catabolic pattern in neuropsychiatric disorders.

Catabolism of tryptophan and tyrosine in relation to the isoprenoid pathway was studied in neurological and psychiatric disorders. The concentration of trytophan, quinolinic acid, kynurenic acid, serotonin and 5-hydroxyindoleacetic acid was found to be higher in the plasma of patients with all these disorders; while that of tyrosine, dopamine, epinephrine and norepinephrine was lower. There was increase in free fatty acids and decrease in albumin (factors modulating tryptophan transport) in the plasma of these patients. Concentration of digoxin, a modulator of amino acid transport, and the activity of HMG CoA reductase, which synthesizes digoxin, were higher in these patients; while RBC membrane Na+-K+ ATPase activity showed a decrease. Concentration of plasma ubiquinone (part of which is synthesised from tyrosine) and magnesium was also lower in these patients. No morphine could be detected in the plasma of these patients except in MS. On the other hand, strychnine and nicotine were detectable. These results indicate hypercatabolism of tryptophan and hypocatabolism of tyrosine in these disorders, which could be a consequence of the modulating effect of hypothalamic digoxin on amino acid transport.

Adult↗

PubMed1999

Decreased hemolysis and lipid peroxidation in blood during storage in the presence of nicotinic acid.

BACKGROUND AND OBJECTIVES: There is increase in lipid peroxidation with consequent increase in hemolysis when blood is stored in di-(2-ethyl hexyl)phthalate (DEHP) plasticized bags. Studies carried out by us and others have indicated the ability of red cells to synthesize NAD+ from added nicotinic acid. Apart from the role of NAD+ in glycolysis, NADPH is required for reduction of oxidized glutathione to its reduced form by glutathione reductase. Reduced glutathione is an important antioxidant, which protects cell membrane from oxidative damage. Reduced glutathione is also involved in the regeneration of vitamin E, another important membrane antioxidant. In view of these, a study was undertaken to find out the effect of addition of nicotinic acid to the citrate-phosphate-dextrose-adenine (CPDA) solution on lipid peroxidation and integrity of red cells when whole blood is stored in DEHP plasticized bags. MATERIALS AND METHODS: Blood was collected in Penpol blood storage bags (which is a DEHP plasticized bag) in CPDA solution in the presence and absence of nicotinic acid. Various parameters of lipid peroxidation and membrane stability - level of malondialdehyde (MDA), conjugated dienes, vitamin E, reduced glutathione, plasma Hb and K+, levels of adenosine triphosphate (ATP) and 2,3-diphosphoglycerate (2,3-DPG) were studied in the blood samples after various periods. RESULTS: Plasma Hb and K+ concentrations were significantly lower in the presence of added nicotinic acid both after 28 and 42 days. Concentration of MDA and conjugated dienes was lower and the levels of reduced glutathione and vitamin E higher in the presence of nicotinic acid. ATP levels were not significantly different, but 2,3-DPG levels were higher. pH of the blood was nearer to 7.0 in the presence of nicotinic acid, while leaching out of DEHP into the blood was significantly lower. CONCLUSION: Inclusion of nicotinic acid in the CPDA solution has a beneficial effect in that (1) it reduces plasma Hb and K+; (2) reduces lipid peroxidation and increases antioxidant protection; (3) maintains pH nearer to 7.0, and (4) decreases the leaching out of DEHP into the blood.

2,3-Diphosphoglycerate↗

PubMed1999

Changes in the composition of erythrocyte membrane during storage of blood in di-(2-ethyl hexyl) phthalate [DEHP] plasticized poly vinyl chloride (PVC) blood storage bags.

Very little information is available on the changes in the erythrocyte membrane composition during storage of blood at 4 degrees C, particularly with respect to the glycosaminoglycans and glycoproteins. In view of this, a detailed study was carried out on the changes in the membrane proteins, glycosaminoglycans (GAG), carbohydrate components of glycoproteins, cholesterol, phospholipids and vitamin E in blood stored in glass bottles and a di-(2-ethyl hexyl) phthalate (DEHP) plasticized PVC bag (Penpol blood bag). Blood was collected in CPDA solution in glass bottles and in Penpol blood bags and kept at 4 +/- 1 degrees C. Analysis was made immediately after blood collection and after 28 and 42 days. Significant increase in the total protein in the erythrocyte membrane was observed during storage of whole blood in glass bottles and Penpol blood bag at 4 degrees C. This increase was progressively more with increase in storage time. Significant changes were also observed in GAG, carbohydrate components of glycoproteins, cholesterol, phospholipids and vitamin E in the erythrocyte membrane under these conditions. The protein:GAG ratio, protein:carbohydrate ratio, cholesterol:phospholipid ratio as well as protein:lipid ratio showed significant increase in the membrane. The extent of these changes was lower in the Penpol bag, indicating the stabilizing effect of DEHP on the erythrocyte membrane.

Blood Preservation↗

PubMed1998

Effect of DEHP [di-(2-ethyl hexyl) phthalate] on lipid peroxidation in liver in rats and in primary cultures of rat hepatocytes.

The effect of DEHP [di-(2-ethly hexyl) phthalate] on lipid peroxidation in the liver in rats and in primary cultures of rat hepatocytes incubated with it was studied. The doses of DEHP used in this study corresponded to the low levels of this substance leaching into blood stored in DEHP plasticised PVC bags. Increased activity of superoxide dismutase (SOD) and catalase, increased concentration of malondialdehyde (MDA) and conjugated dienes and decrease in the concentration of glutathione and vitamin E have been observed in the liver of rats administered DEHP. Primary cultures of rat hepatocytes incubated with DEHP also showed increase in the activity of these enzymes, increase in the concentration of MDA and decrease in vitamin E. These results indicate that DEHP promotes lipid peroxidation. Incorporation of vitamin E along with DEHP into the culture medium containing hepatocytes counteracted these effects.

Animals↗

PubMed1998

Decrease in the concentration of vitamin E in blood and tissues caused by di(2-ethylhexyl) phthalate, a commonly used plasticizer in blood storage bags and medical tubing.

BACKGROUND AND OBJECTIVES: Significant amounts of di(2-ethylhexyl) phthlate (DEHP) leach into blood stored in DEHP-plasticized PVC bags. The aim of this study was to find out whether DEHP at these low levels has any effect on the concentration of vitamin E, an antioxidant which affords protection against free radical damage. MATERIALS AND METHODS: DEHP was administered in low doses (150-750 microg/100 g body weight) to rats intraperitoneally and the concentration of vitamin E in the liver and testes was measured. Concentration of vitamin E was also measured in blood stored in glass bottles in the presence and absence of DEHP and in blood stored in DEHP-plasticized PVC bags. RESULTS: A decrease in the concentration of vitamin E was observed in all cases. Administration of vitamin E to rats and incorporation of vitamin E in the additive solution in the case of blood prevented this decrease. CONCLUSION: DEHP even at very low doses caused a decrease in the concentration of vitamin E in liver and tests of rats given this substance. Blood stored in DEHP-plasticized bags also showed a decrease in the concentration of vitamin E.

Animals↗

PubMed1998

Synthesis of NAD+ in erythrocytes incubated with nicotinic acid and the effect of di-(2-ethyl hexyl) phthalate (DEHP).

Synthesis of NAD+ from nicotinic acid by erythrocytes incubated in SAGM phosphate solution and effect of di-[2-ethyl hexyl] phthalate, a plasticizer commonly used in PVC blood/component storage bags, on this synthesis was studied. Erythrocytes are able to synthesise NAD+ in SAGM (sodium chloride, adenine, glucose, mannitol) phosphate solution and this synthesis was more in the presence of added nicotinic acid (optimum concentration 1 mM). The level of NAD+ decreased when the incubation period was increased from 24 to 48 hr. Glutamine had a deleterious effect on this synthesis, possibly due to the decrease in pH. Di-[2-ethyl hexyl] phthalate had an inhibitory effect on NAD+ synthesis when the cells were incubated in SAGM phosphate solution, either alone or in the presence of added nicotinic acid. There was significant decrease in the release of potassium and haemoglobin from the cells in the presence of nicotinic acid, indicating increased red cell stability.

Adenine↗