Biomedical subjects
Publications and source records attributed to R Kumar.
In severe intra-uterine growth retardation there are low IgG levels, low numbers of B cells and low percentage as well as numbers of T cells in cord blood. Following BCG vaccination given soon after birth, Mantoux conversion and leucocyte migration inhibition response to BCG was defective.
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Two rabbit erythrocyte casein kinases, GTP:casein kinase I and GTP:casein kinase II, have been purified 29 000- and 47 000-fold, respectively. Studies employing sucrose density gradient centrifugation indicate that kinase I has a molecular weight of about 9.5 - 10(5) (25 S) and kinase II about 1.4 - 10(6) (32 S). These enzymes can utilize either ATP or GTP as the phosphoryl donor. Among various protein substrates examined, these kinases catalyze the phosphorylation of casein greater than 50% dephosphorylated phosvitin congruent to 50% dephosphorylated casein greater than phosvitin. Histones, protamine and bovine serum albumin are poor phosphoryl acceptors. Kinetic data indicate that both enzymes are inhibited by high casein substrate concentrations which may be partially relieved by NaCl. Both phosphotransferases require Mg(2+) for activity and are optimally active at pH 9.0. The enzymes have apparent Km values of 2.5 - 10(-5) M for GTP, 2 - 10(-5) M for ATP, and 0.4--0.6 mg/ml for casein. The incorporation of the terminal phosphate of GTP into casein as catalyzed by these enzymes is inhibited to varying degrees by ATP, ITP, ADP, and GDP but not by UTP, CTP, GMP, adenosine 3':5'-cyclic monophosphate, and guanosine 3':5'-cyclic monophosphate. In addition, NaF and 2,3-diphosphoglyceric acid are also found to inhibit the activity of both kinases. The effect of 2,3-diphosphoglycerate is interesting and suggests that this metabolite may regulate the activity of the casein kinases in the red blood cells.
Several 1-(2,4-dichloro and 2,4,5-trichlorophenoxyacetyl)-4-alkyl/arythiosemicarbazides were synthesized and characterized by their sharp melting points and elemental analyses. All substituted thiosemicarbazides protected in vitro hypoosmotic hemolysis of dog red blood cells. These thiosemicarbazides selectively inhibited nicotinamide adenine dinucleotide (NAD)-dependent oxidation of pyruvate and alpha-ketoglutarate, while NAD-independent oxidation of succinate was not affected. These compounds inhibited the activity of monamine oxidase in rat brain homogenate, and the degree of inhibition ranged from 26.5 to 89.2 percent at a final concentration of 0.03mM, with kynuramine as the substrate. Almost all thiosemicarbazides possessed anticonvulsant activity; protection against pentylenetetrazol-induced convulsions in mice ranged from 10 to 70 percent at a dose of 100 mg/kg ip. These results provided evidence of some similarity between the membrane-stabilizing property of these substituted thiosemicarbazides with their ability to exhibit selective inhibition of NAD-dependent oxidations and inhibition of monoamine oxidase. On the other hand, the anticonvulsant activity possessed by these substituted thiosemicarbazides was unrelated to their in vitro antihemolytic and enzyme inhibitory properties.
Activity of adenosine 3',5'-cyclic monophosphate-dependent protein kinase has been measured in the skin of normal controls, patients with non-atopic skin disorders, and those with atopic dermatitis. All samples analyzed displayed the presence of this enzymatic activity. However, the enzyme from the atopic skin did not seem to be dependent on cyclic AMP for activity. Whether this is due to an artifact of isolation of protein kinase or is indeed the true in vivo nature of the enzyme remains to be established.
A female patient aged 25 years developed abdominal and neurological symptoms followed by a photosensitive eruption during pregnancy. She was found to have variegate porphyria on investigation. Investigation of the family revealed on member having latent porphyria. To our knowledge, this is the first report of variegate porphytia from India.
22 patients with Trichophyton rubrum infection were studied for some of their immunological parameters. The trichophytin skin test performed with commercially available Dermatophytin (Hollister-Stier) gave immediate positive reaction in 3 patients. All the other patients gave negative delayed and retarded reactions. In vitro response to PHA of the peripheral lymphocytes was significantly depressed in patients compared to the controls. No relationship could, however, be established between the severity, duration or extent of the disease and the depression of the lymphocyte response. IgG and IfA were found to be within normal limits. IgM levels were significantly depressed which was probably artefactual in nature.
In a study of delayed hypersensitivity in 54 patients with pulmonary tuberculosis who were on specific treatment, 33 patients could not be sensitized to dinitrochlorobenzene (DNCB) although 25 of these were tuberculin (PPD) positive. The majority of the patients also had positive skin reactions to another recall antigen, streptokinase-streptodornase. To exclude a drug effect on DNCB reactivity, 40 untreated patients were studied. Twenty-six (65 per cent) of these did not show DNCB reactivity. The cause for nonsensitization to DNCB was not clear. There was no abnormality in the number of T lymphocytes in the peripheral blood of 28 patients.
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Cell-mediated immune response was investigated in fifteen patients with miliary tuberculosis. Delayed hypersensitivity skin test with "recall" antigens PPD and SKSD was positive in two and one patients respectively. An irritant dose of DNCB failed to induce non-specific inflammatory response in the skin of thirteen patients and the same patients also did not develop contact sensitivity to DNCB. Leucocyte migration test in the presence of Mycobacterium tuberculosis was also negative in eight of eleven patients studied. The proportion of E rosette-forming cells was found to be significantly depressed, though the proportion of EAC rosette-forming cells did not show any abnormality. On repeat skin tests in five patients after 3 months of chemotherapy and clinical improvement four showed a positive PPD and DNCB response. It was concluded that there is a marked degree of secondary immunodeficiency in miliary tuberculosis.
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