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Biomedical subjects

U Kumar

Publications and source records attributed to U Kumar.

99 records · Page 6Linked to original sources

Isolation and culture of biliary epithelial cells from the biliary tract fraction of normal rats.

A method has been developed for the isolation of a population of cells enriched in epithelial lining cells from the bile ducts of normal rats. The procedure utilized digestion by pronase of the white strands of biliary and connective tissue which remained after hepatocytes had been mechanically removed from collagenase-perfused liver. The resulting cell population was enriched in cells whose ultrastructure resembled that of the epithelial cells of intrahepatic bile ducts. Contamination with hepatocytes, hepatocyte nuclei and erythrocytes was less than 2%. The cells have been maintained in short-term culture. The major morphological change during the first 2 days of culture was proliferation of microvilli, but cell protein composition was unchanged when analysed by polyacrylamide gel electrophoresis. A rabbit antiserum against bovine hoof prekeratin was used to immunohistochemically stain the intermediate filaments of biliary epithelium and was shown to stain more than 90% of the cells in the isolated cell population.

Animals↗

Histochemical localization of acetylcholinesterase in the glycogen body (sinus rhomboidalis) of common brown dove, Streptopelia senegalensis and house sparrow, Passer domesticus.

Acetylcholinesterase (AChE) activity was studied in the glycogen bodies of the spinal cords of 2 birds namely Streptopelia senegalensis and Passer domesticus. A possible functional significance of AChE in the light of relative enzymatic localization especially in Hoffmann-Kolliker nuclei (motor cell groups), substantia gelatinosa and other regions of gray matter of 2 avian glycogen bodies has been discussed.

Acetylcholinesterase↗

Role of interaction energy in the specificity of transcription. I-The Watson Crick G-C base pair template.

The purpose of this work is to show that the selectivity of the nucleotide bases in RNA transcription c an be inferred, in principle, from the DNA base pair - RNA base interaction. The catalytic role of enzymes in this process is, therefore, only to form the sugar - phosphate backbone. A systematic study for the evaluation of the interaction energy of the DNA base pair with the enterant RNA bases have been undertaken to elucidate the aforesaid mechanism. Electrostatic hard sphere approximation of Nash and Bradley 1 has been employed. Non bonded induced dipole and London dispersion forces are not taken into account. The present communication gives the results of computations of the interaction energy of the four RNA bases. The results have been discussed with reference to Stent's and Zubay's schemes of RNA transcription.

Base Composition↗

Role of interaction energy in the specificity of transcription. II-The Watson Crick A-U base pair template.

In continuation with work regarding the evaluation of the energy of association of various RNA bases with various base pairs, the results of the computations of the electrostatic interaction energy of A-U base pair with four RNA bases viz. Adenine, Uracil, Guanine and Cytosine have been reported. Non bonded induced polarization and dispersion potentials are not taken into account. Electrostatic hard sphere model of Nash and Bradley has been employed. Computations have been performed to find out the minimum energy configuration out of the various possible complex configurations. Results have been discussed with reference to similar calculations with G-C base pair performed by the authors.

Adenine↗