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Biomedical subjects

G Kumar

Publications and source records attributed to G Kumar.

At least 109 records · Page 6Linked to original sources
PubMed1989

Hemin and cyclic AMP stimulate message-dependent translation in lysates from Friend erythroleukemia cells.

A message-dependent, cell-free translation system was prepared from both uninduced and N,N'-hexamethylene-bis-acetamide-induced Friend erythroleukemia cells following modification of standard protocols. Active extracts were prepared by lysing Friend erythroleukemia cells in hypotonic buffer containing 50 microM hemin and 10 mM cyclic adenosine monophosphate (cAMP), and assaying translation in vitro in the absence of exogenous nucleoside triphosphates. Both hemin and cAMP were required for full activity and appeared to act by prolonging initiation in vitro. Following treatment of cell extracts with micrococcal nuclease, brome mosaic virus, globin, equine herpesvirus type 1, and frog virus 3 mRNA were efficiently translated to yield full-sized products. Using brome mosaic virus as a test message, levels of translation equivalent to 30%-50% of that seen in mock-treated lysates were obtained. These results attest to the translational efficiency of extracts prepared and assayed in the manner described above, and suggest that such extracts may be useful both for routine translational studies, and as a tool to dissect translational changes accompanying erythroid differentiation in vitro.

Acetamides↗
PubMed1988

Minimal change disease as the etiology of the nephrotic syndrome in a patient with angioimmunoblastic lymphadenopathy.

Glomerular lesions have rarely been reported with angioimmunoblastic lymphadenopathy (AILD). A patient with histologically documented AILD developed the nephrotic syndrome. Renal biopsy demonstrated minimal change disease. Both the lymphadenopathy and the nephrotic syndrome spontaneously remitted in this patient. Prior reports of renal disease in AILD and atypical lymphoproliferative disorders are discussed. An association between the minimal change lesions and AILD is suggested.

Humans↗
PubMed1985

Molecular cloning and regulated expression of the human c-myc gene in Escherichia coli and Saccharomyces cerevisiae: comparison of the protein products.

mRNA from human HL-60 cells was used to prepare a cDNA library, from which two full-length clones that encompass the complete c-myc coding region were isolated. One clone, pM1-11, contains all three exons of human c-myc. The second clone, pM4-10, represents a relatively rare transcript that initiated in the first intron and includes the coding exons 2 and 3. The cDNA insert in pM1-11 was used to express the human c-myc protein in both prokaryotic and eukaryotic cells. Insertion of the coding sequences in exons 2 and 3 into the appropriate expression vectors yielded detectable c-myc protein in Escherichia coli lacking the Lon protease and in Saccharomyces cerevisiae upon induction. The protein produced in E. coli has an apparent size of 60 kDa and appears to be unmodified, as it is identical in size to the protein synthesized in an in vitro system. In contrast, yeast cells synthesize two myc proteins, of 60 kDa and 62 kDa. The difference in apparent molecular mass between the two proteins appears to be due, in part, to phosphorylation. Subcellular fractionation of yeast cells showed that the c-myc phosphoprotein is located predominantly in the nuclear fraction.

Base Sequence↗
PubMed1982

The peptidyltransferase center of Escherichia coli ribosomes: binding sites for the cytidine 3'-phosphate residues of the aminoacyl-tRNA 3'-terminus and the interrelationships between the acceptor and donor sites.

The substrate specificity of the acceptor site of peptidyltransferase of Escherichia coli 70 S ribosomes was investigated in Ac-Phe-tRNA . poly(U) . 70 S ribosome (system A) and tRNC-A-Phe . poly(U) . C-A-C-C-A-Phe . 70 S ribosome (system B) systems by using C-C-A-Gly, C-C-A-Phe, C-A-Gly and C-A-Phe as analogs of the 3'-terminus of aminoacyl-tRNA. It was found that an addition of CP residue to C-A-Gly and C-APhe resulted in an increase of the acceptor activity in system A; the increase is more remarkable for C-A-Gly than for C-A-Phe, while the acceptor activities of C-C-A-Gly and C-C-A-Phe are roughly similar. On the other hand, dramatically increased binding affinities of C-C-A-Phe and C-C-A-Gly relative to C-A-Phe and C-A-Gly for the A site of peptidyltransferase were observed in system B using an inhibition assay; C-C-A-Phe binds much more strongly than C-C-A-Gly. The results indicate the important role of the third CP residue and the aminoacyl moiety of the 3'-terminus of aminoacyl-tRNA in the interaction with the acceptor site of peptidyltransferase, as well as the existence of cooperative effects between A and P sites of peptidyltransferase. These effects, depending on an occupancy of P site, may significant the specificity of the peptidyltransferase A site.

Acyltransferases↗
PubMed1979

Active transport of calcium in membrane vesicles from Mycobacterium phlei.

Active transport of calcium ions has been demonstrated in inside-out membrane vesicles from Mycobacterium phlei mediated by respiratory linked substrates as well as by ATP hydrolysis. The uptake of calcium exhibited an apparent Km of 80 microM and V of 16.6 nmol calcium uptake x min-1 x mg protein-1. A fortyfold concentration gradient for calcium ions was calculated for both the ATP-induced and the respiration-induced transport of calcium. Removal of coupling-factor-latent ATPase resulted in the complete loss of ATP-driven Ca2+ transport whereas the respiration-driven uptake was reduced by 40-50%. The uptake of calcium was inhibited by the proton conducting ionophores carbonylcyanide m-chlorophenylhydrazone and Gramicidin-D. The accumulated calcium was freely exchangeable with external calcium and was rapidly released by the addition of inhibitors of energy transduction, proton-translocating uncouplers or the ionophore A23187. The uptake of the weak base, methylamine, upon the oxidation of respiratory-linked substrates or the hydrolysis of ATP showed the generation of a protein gradient (inside acidic) which was partially collapsed on the addition of calcium ions. These results suggest that a Ca2+/H+ antiport mechanism may be responsible for the transport of calcium.

Adenosine Triphosphatases↗
PubMedDate not supplied

Epidemiological characteristics of new borns in a rural community.

All births (1211) were recorded in a rural area for 1985 by monthly domiciliary visits and the sociological characteristics were collected from mothers within a month. The analysis of 1201 births is presented: 52.7% were male births, 95.7% were delivered in village itself, 80.4% were delivered by trained dais, 99.5% were live born, 12.9% were born before 37 weeks of gestation, 61.5% were put to breast feed within 6 hours, 35% were of gravida 4 and above, 68.9% did not receive any antenatal care, 67.1% had not received any tetanus toxoid, 70.8% did not receive any folifer tablet, 0.8% had abortion and another 0.8% had still birth in preceding outcome, 1.58% had lost a live born dead in preceding out come, 89.6% stopped breast feeding at conception, 31.7% had birth interval less than 2 years, but 2.2% had less than one year, 2/3rd were born in second half of the year, 17.8% had taken extra food during pregnancy, 21.2% reduced the work after becoming pregnant, 9.5% were born to mothers of less than 20 years age, 98.5% of mothers were housewives and 95.9% mothers were illiterate, 33.5% were born in nuclear family, 22.3% were living in 'Kacha' house, 34.8% had no electricity connection, 37.0% were born to land less, 42.2% had no radio in the house, 7.1% had no conveyance, 52.0% families had piped water supply. These findings have been discussed here.

Birth Rate↗
PubMedDate not supplied

Prevalence of tobacco use among school and college going adolescents of Haryana.

The prevalence of tobacco use among the school and college going adolescents of Haryana, a state in northern India was studied. 1130 male and 256 female students were given a self administered questionnaire regarding tobacco use. 160 (14.2%) male and 6 (2.3%) female students reported to have smoked at any time in the past. The prevalence of current smoking (defined as smoked in last one week) was only 7.1%. Of the 166 ever smokers, 44% had started this habit between 10 to 15 years of age. There was no rural-urban difference. Univariate analysis showed, male sex, age > 15 years, smoking by father, mother, sister, and friends to be significantly associated with smoking by the adolescent children. By logistic regression, only smoking by friend (O.R. 6.14), brother (O.R. 1.74) and male sex (O.R. 4.67) were found to be significantly associated with smoking by adolescent children. About 8% of the smokers were spending more than Rs. 10 per week on this habit. Both the smokers and non smokers were well aware of the adverse health effects of smoking indicating that mere provision of information on hazards of smoking may not be enough to reduce the prevalence of smoking. A more concerted effort for inducing behavioural change including legislation, communication is called for the fight against smoking.

Adolescent↗