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Biomedical subjects

A Tulp

Publications and source records attributed to A Tulp.

54 records · Page 3Linked to original sources
PubMed1978

Binding of the chemical carcinogen N-hydroxy-acetyl-aminofluorene to ploidy classes of rat liver nuclei as separated by velocity sedimentation at unit gravity.

A large sedimentation device was developed that allows separation of 5 X 10(8) rat liver nuclei by velocity sedimentation at unit gravity. Using the apparatus isolated rat liver nuclei were separated into classes of diploid stromal (Von Kuppfer, sinusoidal lining) nuclei, diploid parenchymal nuclei and tetraploid parenchymal nuclei respectively. DNA content and volume of the nuclei were measured. Diploid nuclei were 100% pure; tetraploid nuclei 98%. The in vivo binding of the liver carcinogen [3H]-N-hydroxy-AAF to these classes of nuclei was determined (total binding to protein, DNA and RNA). Binding and the subsequent removal of the fluorene derivatives was registered as a function of time. At all stages diploid stromal nuclei bound 2.6--5 times less carcinogen than did diploid parenchymal nuclei. Tetraploid parenchymal nuclei bound more than twice (2.3--3.95) the amount, that was present in their diploid counterpart. This effect became more pronounced 11 days after application of N-hydroxy-N-acetyl-2-aminofluorene. DNA was enzymatically purified from pooled classes of the various nuclear types. For purified DNA also it was found that DNA derived from diploid stromal nuclei bound 2.6--2.8 times less carcinogen than did DNA derived from diploid parenchymal nuclei.

Animals↗
PubMed1976

Separation of intact rat hepatocytes and rat liver nuclei into ploidy classes by velocity sedimentation at unit gravity.

A system is described which permits the separation of isolated hepatocytes and isolated rat liver nuclei belonging to different ploidy classes by velocity sedimentation at unit gravity. The problem of obtaining single cells suspensions is discussed and preparations were obtained that contained 96% single hepatocytes. By improving the sedimentation method, it took 2.5 h to separate rat liver nuclei on sucrose gradients into diploid and tetraploid ploidy classes. Recoveries were generally over 95%. The diploid band was 99% pure. DNA and protein content of the ploidy classes were measured. After partial hepatectomy and [3H]thymidine injection it was found that the label moved largely into the tetraploid compartment. Isolated hepatocytes were fractionated in 1 h on Ficoll gradients. Erythrocytes were separated from small nucleated cells and the population of hepatocytes was clearly separated from these two cell populations. Diploid hepatocytes were 80% and tetraploid hepatocytes were 99% pure. Viability was about 80% after fractionation. The gene dosage of NADPH cytochrome c reductase, succinate dehydrogenase and lactate dehydrogenase was estimated in diploid and tetraploid hepatocytes. Gene dosage was equal in diploid and tetraploid hepatocytes for succinate dehydrogenase and NADPH cytochrome c reductase. It is suggested, after correcting for non-viable tetraploid hepatocytes, that the gene dosage of lactate dehydrogenase was significantly lower in diploid than in tetraploid hepatocytes.

Animals↗
PubMedDate not supplied

Analysis of members of the Ig-gene superfamily by thermal gradient polyacrylamide gel electrophoresis.

A solid aluminum block, connected with a warm and cold thermostated waterbath, provided for a linear transversal temperature gradient (TG) during polyacrylamide gel electrophoresis (PAGE). Noncovalently bound heavy chain dimers as well as heavy-light chain dimers, derived from human monoclonal IgG, could be melted into monomers using a 40-75 degrees C TG under conditions of sodium dodecyl sulfate-PAGE. Using native PAGE, major histocompatibility complex (MHC) class I molecules, preloaded with the iodinated peptide FAPGNYPAL could be melted in a 4-40 degrees C TG to release the peptide. The method is in general applicable to thermal stability analysis of noncovalently bound hetero-oligomers if the product after melting possess different electrophoretic mobilities.

Amino Acid Sequence↗
PubMedDate not supplied

Interference with HIV-induced syncytium formation and viral infectivity by inhibitors of trimming glucosidase.

Human immunodeficiency virus (HIV), the causative agent of AIDS, infects human lymphocytes and monocytes. An interaction between the viral envelope gp 120 and CD4 protein is required to initiate an infectious cycle. HIV infection in vitro induces syncytium formation by cell-to-cell fusion; this aspect of viral cytopathogenicity is even more dependent on gp120-CD4 interactions. That gp120 is extremely heavily glycosylated (31-36 N-linked glycans per molecule), suggests involvement of N-linked glycans in the gp120-CD4 interaction. We therefore investigated the effects of castanospermine, 1-deoxynojirimycin (dNM) and 1-deoxymannojirimycin (dMM), three trimming glycosidase inhibitors which perturb N-linked glycan structure, on induction of the formation of syncytium between HIV-infected and CD4-expressing cells. The glucosidase inhibitors castanospermine and dNM, but not the mannosidase inhibitor dMM, inhibited syncytium formation and interfered with infectivity. The potential of glucosidase inhibitors as anti-HIV therapeutic agents deserves further investigation, especially because dNM and related compounds show little toxicity in vitro and in vivo.

1-Deoxynojirimycin↗
PubMedDate not supplied

Use of a unit gravity sedimentation chamber for the purification of Mycobacterium leprae.

The present paper summarizes results concerning a mild isolation method of Mycobacterium lepraemurium and M. bovis-BCG from host tissues, and describes the application of such a method in purifying M. leprae (M1) from either infected armadillo tissues or human skin biopsies. This isolation method consists of homogenization, two-phase partition in dextranpolyethylene glycol and finally sedimentation in sucrose gradient using a unit gravity chamber. Such a purified M1 preparation appears to be devoid of host-tissue contaminants as examined by light and electron microscopy as well as by a radioimmuno spot test. The results indicate that the present method is mild enough to allow the purification of M1 from infected host tissues with in vivo conservation of antigenicity and viability of the bacilli.

Animals↗