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J Löwer

Publications and source records attributed to J Löwer.

61 records · Page 4Linked to original sources
PubMed1983

Structural organization of unique retrovirus-like particles budding from human teratocarcinoma cell lines.

Human teratocarcinoma cells cultured in vitro can be induced to produce retrovirus-like particles. The induction procedures are the same as those previously shown to induce the synthesis of animal retroviruses. Electron microscopical evidence is presented that the human teratocarcinoma-derived (HTD) particles are most closely related to the type C retrovirus strains. HTD particles can be banded at 1.16 g/ml in linear sucrose gradients, the characteristic density for retroviruses, and subsequently be used for negative staining and fine structure analysis.

Cell Line↗
PubMed1983

Retroviruses in human tumors.

Retroviruses received widespread attention in the past not only because they caused tumors in animals and, perhaps, in man, but also because they served as useful tools to elucidate molecular mechanisms involved in the control of eukaryotic gene expression. In this brief overview, evidences are presented that retrovirus-like particles can regularly be demonstrated in human teratocarcinomas cultured in vitro. These viruses are morphologically reminiscent of animal retrovirus strains but show also unique structural features. The viruses possess endogenous reverse transcriptase activity and can be banded at 1.16 g/ml in sucrose gradients, a density characteristic of retroviruses. They can clearly be distinguished from animal retrovirus strains on immunological grounds. We will also briefly summarize the data accumulating for the human T-cell lymphoma viruses (HTLV) which were recently discovered first by Gallo et al. and independently by Hinuma and Miyoshi. HTLV seem to play an etiological role in the establishment of human adult T-cell leukemia/lymphoma and thus represent the first pathogenic human retroviruses.

DNA, Neoplasm↗
PubMed1982

Synthesis of retrovirus-like particles in testicular teratocarcinomas.

Two lines of evidence led to the investigation of human teratocarcinoma cells in vitro for oncogenic retroviruses: the observation by electron microscopy of retrovirus-like particles budding from the syncytial trophoblasts of human placentas, and the demonstration that teratocarcinoma patients before treatment show a high serum antibody reactivity against envelope proteins of mammalian retroviruses. In all 5 teratocarcinoma cell lines studied so far, retrovirus-like particles have been detected by electron microscopy. The production of these human teratocarcinoma-derived (HTD)-particles is enhanced by induction procedures known to be effective in animal virus model systems. In parallel, virus induction also increases the level of chorionic gonadotropin in the culture supernatant, demonstrating syncytial trophoblast-like cells in the heterogeneous cell population of teratocarcinomas which could be responsible for HTD-particle production. The origin of these virus-like particles--endogenous or exogenous--as well as their role in the pathogenesis of teratocarcinomas is not known so far. The potential value of serum antibody reactivity in teratocarcinoma patients as a diagnostic marker is discussed.

Cell Line↗
PubMed1979

Comparison of radioimmunoprecipitation assays for the detection of human anti-tumor virus antibodies.

The demonstration of human antibodies reactive in radioimmunoprecipitation assays (RIAs) with primate tumor virus (oncornavirus) antigen has implications for a possible previously published negative findings and led to considerable scientific controversy. We feel much of the discrepancy may be of methodological origin. An attempt is therefore made in this communication to resolve these apparent discrepancies by comparing various published parameters of the RIAs used in the search for human antibodies reactive with oncornavirus antigens.

Animals↗