RESUMEN
SV40 can induce proliferation of primary cells from various origins and by making them escape from senescence confer a potential of unlimited division characteristic of established cell lines. We have studied this effect called immortalization with various mutants of the SV40 early genes. The results establish that the immortalized phenotype is controlled by the A gene in a reversible fashion. Cells immortalized at 33 degrees by a tsA mutant, revert to a "mortal" or senescent-like phenotype after temperature shift up to 39 degrees. The nature of these striking phenotypic changes is discussed.
Asunto(s)
Línea Celular , Transformación Celular Viral , Genes Virales , Virus 40 de los Simios/genética , Animales , Supervivencia Celular , Embrión de Mamíferos , Fibroblastos , Ratones , RatasRESUMEN
Experiments using the tsA 58 allele of the SV 40-A gene have demonstrated that the SV 40 large T-antigen is strictly required both for immortalization and induction anchorage independence of cells. It has been suggested that the immortalized phenotype is mediated by an extra cellular factor. The synthesis and/or the excretion of this factor in a medium is controlled by the A gene.
Asunto(s)
Transformación Celular Neoplásica , Virus 40 de los Simios/genética , Alelos , Animales , Antígenos Virales de Tumores/genética , Células Cultivadas , Ratones , Mutación , Virus 40 de los Simios/inmunologíaRESUMEN
A brief synopsis of problems with hiatus herniorrhaphy surgery over its 25-year history includes extensive surgery, recurrences, and postoperative swallowing difficulties. A review of the simple central tendon hiatal herniorrhaphy technic and seven-year results include the adoption of a mersilene strip rather than external rectus fascia in anchoring the esophagogastric junction to the central tendon. The same excellent exposure and visibility allowing the lower esophageal segment to be well secured definitely within the abdomen is completely illustrated. Seven-year results in 138 patients operated upon are reviewed including mortality, recurrence rates, postoperative dysphagia, gas-bloat, and loss of regurgitating ability.