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Biomedical subjects

R Mihalik

Publications and source records attributed to R Mihalik.

58 records · Page 4Linked to original sources
PubMedDate not supplied

New in vitro line from a human (B) non-Hodgkin lymphoma.

An in vitro cell line (HT 58) has been established from a human (B) NHL xenograft. The lymphoma cells in culture retained their lymphoblastic appearance, DNA-content, IgM/lambda monoclonality and many immunophenotypic markers. The clonal chromosomal abnormalities involved the chromosomes 1, 2, 3 and 14. The cells expressed and produced chondroitin sulfate proteoglycans identified with mAbs that were raised against human articular cartilage CSPG. The cells also released IgM into the medium as well as substances that stimulated the proliferation of activated normal peripheral B-cells.

Antibodies, Monoclonal↗
PubMedDate not supplied

Loss of transforming growth factor beta 1 regulatory activity in human non Hodgkin lymphomas.

Since TGF beta 1 inhibits the proliferation of normal B-cells, its disturbed activity in B cell lymphomas is conceivable. We found high expression of TGF beta 1 mRNA in three human B cell non-Hodgkin lymphoma xenografts; also, the gene product (in latent form) was detectable in all lymphoma cells. However, on exposing the cells to exogenously activated TGF beta 1, the incorporation of tritiated thymidine decreased in normal (murine thymocytes, human peripheral mononuclear cells), but not in lymphoma cells. These observations suggest the malfunction of TGF beta 1 mediated regulatory pathway (e.g. insufficient activation or receptor expression) which can contribute to the unlimited expansion of a lymphoid clone. The opposite expression of c-myc to TGF beta and the retained sensitivity to anti-IgM indicate that c-myc and Ig receptor can operate independently of TGF beta in the regulation of lymphoid cell proliferation.

Animals↗
PubMedDate not supplied

Modulation of apoptosis signaling in etoposide-treated lymphoma cells.

Signals of etoposide (ETO) induced apoptosis were studied in a human (B) lymphoma cell line, HT58. Morphology and DNA fragmentation assays proved the appearance of apoptosis after a short ETO treatment (4 hours). Modulation of signal components of this apoptotic pathway resulted the following a) phorbol ester (PMA) or heat shock inhibited apoptosis, which was prevented by staurosporine b) 3-amino-benzamide, a potent poly(ADP-ribose)polymerase inhibitor, had no significant effect; c) cysteine reactive compounds, such as iodoacetamide and phenylarsine oxide, as well as protease inhibitor TPCK were very active inhibitors of apoptosis; d) protein synthesis inhibitor, cycloheximide, potentiated cell death; e) the ETO-induced p53 protein overexpression had neither enhancing nor protecting effect on the apoptotic process. In conclusion, in the majority of HT58 lymphoma cells the apoptotic machinery is "primed" (the components are already expressed) and ETO-induced apoptosis is regulated by STA sensitive phosphorylation and proteolysis by cystein proteases, but not affected by ADP-ribozylation or p53.

Apoptosis↗