Assuntos
Infecções por Citomegalovirus , Infecções Oculares Virais , Ceratite , Caxumba , Endotélio Corneano , HumanosRESUMO
A sample of 214 reciprocal 2-break translocations observed in fibroblasts, both after accidental 'in vivo', and experimental 'in vitro' gamma-irradiation, was studied. The distribution of the breaks along the chromosomes does not seem at random. The minimal possible imbalance that these translocations could induce by malsegregation, if they existed in germ cells, was estimated. These imbalances were compared with the chromosomal trisomies and monosomies known to be compatible with life after birth in man. It is concluded that about 2/5 of the radiation-induced translocations might induce a viable trisomy and/or monosomy. This result, similar to that previously obtained in human lymphocytes, indicates the validity of the extrapolation from one tissue to another, and hopefully to germ cells.
Assuntos
Aberrações Cromossômicas , Cromossomos/efeitos da radiação , Fibroblastos/ultraestrutura , Translocação Genética , HumanosRESUMO
The cytogenetic study of skin fibroblasts from a young boy, heavily irradiated by handling of an iridium-192 source of 25 curies is reported. About half of the cells examined had chromosomal abnormalities. The same clone, with multiple chromosome rearrangement, was observed in cultures from biopsies obtained 25 and 35 months after the accident. Several other clones were detected in vitro. The results obtained from cultures of biopsies from different locations show that no direct relationships were found between the absorbed dose and the frequency of stable chromosomal rearrangements. The comparison of the intrachromosomal rearrangements, mostly inversions, observed in this study with those detected in human pathology, in irradiation experiments in vitro, and in various species of primates indicates that these rearrangements do not occur at random.
Assuntos
Aberrações Cromossômicas , Transtornos Cromossômicos , Lesões por Radiação/genética , Pele/efeitos da radiação , Células Cultivadas , Criança , Bandeamento Cromossômico , Células Clonais , Fibroblastos/efeitos da radiação , Humanos , Cariotipagem , MasculinoRESUMO
The rearranged chromosomes derived from reciprocal translocations or dicentric-acentric formations, observed 48 h after their induction by irradiation at Go phase, have a clear tendency to be closer together than their normal homologues. This tendency disappears in longer cultures, and does not exist when many different constitutional reciprocal translocations are considered together. It indicates that the chromosomes having exchanged segments remain adjacent at the following metaphase, and thus, that metaphase plates reflect, at least partially the interphase arrangement of chromosomes.
