Repair of UV damage in plasmid DNA by human fibroblasts

Summary Plasmid DNA from Bacillus subtilis was introduced into monolayers of human fibroblasts by means of a modification of the calcium phosphate coprecipitation technique, comprising centrifugation of the coprecipitate onto the cells and treatment with polyethyleneglycol. The amount of DNA resistant to removal from the monolayers ranged from 10% to 15% of the input DNA. By determination of the biological activity of the plasmid DNA, re-extracted after various periods following entry into the fibroblasts and subsequently used as donor for B. subtilis protoplasts, it was shown that the activity of the plasmid DNA was gradually lost. When ultraviolet light-inactivated plasmid DNA was used as donor, reactivation of the plasmid was observed, which was completed within 2 h. The dose-dependent incorporation of [¹⁴C]-thymidine suggests that DNA repair processes were involved in reactivation of the plasmid DNA.     

Germacranolides from Schkuhria anthemoidea

The isolation of eucannabinolide and three new sesquiterpene lactones from Schkuhria anthemoidea is reported. The structures and stereochemistries of the new compounds were established by chemical and spectroscopic means. The structure of santhemoidin B was confirmed by X-ray crystallography.     

Intracellular CBG-like molecules in the rat pituitary

The localization of transcortin (CBG) in pituitary cells of the rat was investigated using the peroxydase-antiperoxydase (PAP) technique. A rabbit antiserum against purified rat plasma transcortin was used as the primary antiserum. Transcortin-like (CBG-like) immunoreactive products were found in the cytoplasma of certain cells in the anterior pituitary, but not in the intermediate lobe and weakly in the posterior pituitary. It is postulated that the CBG-like molecules participate in the cellular uptake process of corticosterone, thereby modulating the feedback signal of this steroid on pituitary function.     

Antigenic structure of simian virus 40 large tumor antigen and association with cellular protein p53 on the surfaces of simian virus 40-infected and -transformed cells.

The antigenic structure of simian virus 40 (SV40) large tumor antigen (T-ag) in the plasma membranes of SV40-transformed mouse cells and SV40-infected monkey cells was characterized as a step toward defining possible biological function(s). Wild-type SV40, as well as a deletion mutant of SV40 (dl1263) which codes for a truncated T-ag with an altered carboxy terminus, was used to infect permissive cells. Members of a series of monoclonal antibodies directed against antigenic determinants on either the amino or the carboxy terminus of the T-ag polypeptide were able to precipitate surface T-ag (as well as nuclear T-ag) from both SV40-transformed and SV40-infected cells. Cellular protein p53 was coprecipitated with T-ag by all T-ag-reactive reagents from the surface and nucleus of SV40-transformed cells. In contrast, T-ag, but not T-ag-p53 complex, was recovered from the surface of SV40-infected cells. These results confirm that nuclear T-ag and surface T-ag are highly related molecules and that a complex of SV40 T-ag and p53 is present at the surface of SV40-transformed cells. Detectable levels of such a complex do not appear to be present on SV40-infected cells. Both the carboxy and amino termini of T-ag are exposed on the surfaces of SV40-transformed and -infected cells. The possible relevance of the presence of a T-ag-p53 complex on the surface of SV40-transformed cells and its absence from SV40-infected cells is considered.     

Glioblastoma cells release interleukin 1 and factors inhibiting interleukin 2-mediated effects

Studies were designed to investigate whether the cellular immunodeficiency state observed in human glioblastoma patients could be due to inhibitory factors released by the tumor cells. Cultured human glioblastoma cells were found to secrete an interleukin 1-like factor (m.w. 22,000) and a factor (m.w. 97,000) that inhibits interleukin 2 (IL 2)-dependent T cell mechanisms. This is demonstrated by its inhibitory effect on the IL 2-induced proliferation of T cell clones and on the induction of alloreactive cytotoxic T cells in mixed lymphocyte cultures. Additionally the glioblastoma cell-derived 97,000-m.w. factor inhibited growth of neuroblasts but not of fibroblasts and thus shares the characteristics of the neuroblast growth inhibition factor (NGIF) previously detected in the supernatant of fetal rat glia cell cultures. If released by glioblastoma cells in vivo, the factor may contribute to impaired immunosurveillance and to the cellular immunodeficiency state detected in the patients.     

Oncogenicity by adenovirus is not determined by the transforming region only.

We have constructed a nondefective recombinant virus between the nononcogenic adenovirus 5 (Ad5) and the highly oncogenic Ad12. The recombinant genome consists essentially of Ad5 sequences, with the exception of the transforming early region 1 (E1) which is derived from Ad12. HeLa cells infected with the recombinant virus were shown to contain the Ad12-specific E1 proteins of 41 kilodaltons (E1a) and 19 and 54 kilodaltons (both encoded by E1b). The recombinant virus replicated efficiently in human embryonic kidney cells and HeLa cells, showing that the transforming regions of Ad5 and Ad12 had similar functions in productive infection. After the recombinant virus was injected into newborn hamsters, no tumors were produced during an observation period of 200 days. Thus, despite the fact that all products required for oncogenic transformation in vitro were derived from the highly oncogenic Ad12, the recombinant virus did not produce tumors in vivo. These data show that tumor induction by adenovirus virions is not determined only by the gene products of the transforming region.     

A new experimental model for myocutaneous flaps: latissimus dorsi of the rabbit--an anatomic study

A new experimental model, the latissimus dorsi flap of the rabbit, was studied. This was found to be a relatively inexpensive research model. Its use is advocated for composite tissue transfer as transposition, island, or free myocutaneous flaps.     

Effects of partial hepatectomy on various blood and hepatic parameters in the rainbow trout (Salmo gairdnerii, Rich.)

After 36% of hepatic mass removal , rainbow trout recovered its initial liver weight in 20-30 days, i.e., with a regeneration rate clearly lower than in mammals. During early regeneration process hematocrit index and hemoglobin content were slightly decreased, but both parameters rapidly reached their normal values. The evolution of both glycaemia and hepatic glycogen content supported the idea of the existence of a late regeneration wave, which, in this case, could begin at about the 20th post-operative day.