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Biomedical subjects

J Belehradek

Publications and source records attributed to J Belehradek.

49 records · Page 3Linked to original sources
PubMed1979

Inheritance of malignancy in somatic cell hybrids.

After a recall of the importance of early basic developments of in vitro established cell lines for investigations on malignant transformation, a survey of essential steps in the study of malignancy by means of somatic cell hybridization is presented. Since the early sixties, in vitro crosses of malignant versus nonmalignant parental cells have provided many experimental models in which mechanisms of expression of malignancy have been approached. Allogenic as well as xenogenic cell matings resulted in tumor-producing or nontumorigenic hybrids which have been analyzed, particularly in terms of karyology in order to determine possible chromosomal patterns linked with inheritance of malignancy and its suppression. The authors discuss the successive concepts devised for interpretation of experimental data, implicating specific genetic "normalizing" information, genetic dosage as well as, more recently, epigenetic and cytoplasmic mechanisms.

Animals↗
PubMed1974

Actinomycin-D-resistant in vitro mouse cell line derived from a methylcholanthrene-induced sarcoma: decrease of malignancy and antigenic characteristics.

The tumorigenic EPO clonal cell line, derived from a methylcholanthrene-induced murine sarcoma, was exposed to increasing concentrations of actinomycin D and gave rise to a subline, resistant to 0.02 mug of actinomycin D per ml of medium, which was designated EPO/ADj. Drug resistance was accompained by a striking decrease of tumorigenic capacity as determined by the tumor take incidence and tumor growth rate in syngeneic C57BL/6 mice (normal and X-irradiated), as well as by tumor take incidence in the cheek pouch of cortisone-treated weanling Syrian hamsters. One of the tumors obtained after inoculation of EPO/ADj cells into syngeneic mice was reexplanted in culture and developed as the EPO/ADj/T subline. It was found to be relatively resistant to actinomycin D as compared to the parental EPO cells. The morphology of cells changed with actinomycin-D-resistance: EPO/ADj cells were more spread and flattened and less overlapping than the original fibroblast-like EPO cells. EPO/ADj/T cells, however, had an aspect similar to that of EPO cells. No major differences were seen between the karyotypes of EPO, EPO/ADj and EPO/ADj/T cells. Tumor-specific antigen(s), characteristic of drug-sensitive, parental EPO line, was expressed in the resistant EPO/ADj and EPO/ADj/T lines, as shown by: (a) transplantation resistance to challenge with EPO cells in syngeneic mice pretreated with EPO/ADj cells; and (b) cross-reactivity in indirect immunofluorescence tests performed with sera from syngeneic animals hyperimmunized with EPO or EPO/ADj cells. Furthermore, an additional surface antigen(s), absent from EPO cells, was demonstrated in EPO/ADj and EPO/ADj/T cells by means of immunofluorescence tests performed with specific anti-EPO/ADj syngeneic sera previously absorbed on EPO or EPO/ADj cells.

Animals↗
PubMedDate not supplied

Electrochemotherapy tumor treatment is improved by interleukin-2 stimulation of the host's defenses.

We have recently described a new antitumor treatment, electrochemotherapy (ECT), based on the large local potentiation of the effects of the chemotherapeutic agent bleomycin (BLM) by electric pulses (EP) delivered at the tumor site. We demonstrate here that the host's immune response participates in cure achievement. We obtain an increase of the rate of completely cured animals by injecting mice with interleukin-2 (IL-2).

Animals↗