Increased base change mutations at G:C pairs in Escherichia coli deficient in endonuclease III and VIII.

Various types of mutation induced by oxidative DNA damage, induced by hydrogen peroxide and riboflavin photosensitization, were determined in Escherichia coli (E. coli) mutants deficient in endonuclease III (endo III) and endonuclease VIII (endo VIII). The majority of hydrogen peroxide-induced and spontaneous mutations consisted of G:C to A:T and to T:A base changes, shown on the mutation assay system by a reversion at a specific site of the lacZ gene. Base changes were also localized at G:C pairs in the mutation of the supF gene, induced by riboflavin photosensitization, which specifically yields 7,8-dihydro-8-oxoguanine (8-oxoG). G:C to T:A and to C:G transversions dominated in both mutants. These results suggest that endo III and endo VIII are involved in the repair of oxidative lesions of guanine.

The sex differences in cord-blood cholesterol and fatty-acid levels among Japanese fetuses.

We examined serum cholesterol and fatty-acid levels of cord blood and maternal blood samples collected from 193 Japanese fetuses and their mothers. Our study, which is the largest study of this kind ever conducted in Japan, is the first Japanese study reporting that total, high density lipoprotein (HDL) and non-HDL cholesterol levels in females were statistically significantly higher than those in males; the sex differences of total, HDL and non-HDL cholesterol levels were 8.5 mg/dl (P = 0.002), 4.5 mg/dl (P = 0.004) and 4.1 mg/dl (P = 0.045), respectively. The sex difference of total cholesterol was attributable to both HDL and non-HDL cholesterol. The sex of fetuses didn't show evident differences in cholesterol levels in maternal sera. Fatty-acid levels in cord blood were also higher in female fetuses than in male fetuses. However, none of the differences except for monoene fatty acids were statistically significant. Further investigations seem warranted to elucidate the mechanisms involved in our results.

On the developing periodontal ligament of rats, using a new specimen preparation method for SEM in comparison with histochemistry.

To visualize the cells and fibers of the developing periodontal ligament (PDL) by scanning electron microscope (SEM), we examined a new tissue preparation method including decalcification, sectioning by cryomicrotome, and chemical treatment for removal of cells or collagen fibers. The advantages of this method were as follows: (1) it was possible to expose the restricted area, (2) it caused no damage by heat or various embedding agents such as paraffin or resin, and (3) it was possible to make comparisons the SEM observation with histochemical or immunohistochemical observation using the neighboring sections. We could classify the development of PDL into three stages by alkaline phosphatase (ALPase) activity and observe each stage by this method. Stage I was the zone of dental follicle proper that showed negative ALPase activity. Stage II was the tissue surrounding the disrupted Hertwig's epithelial root sheath (HERS) which evinced intense ALPase activity, and stage III was the further advanced zone of differentiation that displayed moderate ALPase activity. Using this new method for SEM, cells with many processes and thin fibers were seen irregularly at stage II. On the other hand, at stage III, fibers were seen as interconnecting meshworks of thick bundles and cells that showed regularly arranged rows running obliquely to the surface of the root and alveolar bone. At the transition between stages II and III, the thickness and orientation of fibers changed abruptly.

The process of calcification during development of the rat tracheal cartilage characterized by distribution of alkaline phosphatase activity and immunolocalization of types I and II collagens and glycosaminoglycans of proteoglycans.

The rat tracheal cartilage was shown to calcify during development. The process of calcification was characterized in terms of distribution of alkaline phosphatase (ALP) activity and alterations to immunolocalization of types I and II collagens and glycosaminoglycans of proteoglycans during the development of the tracheal cartilage, in comparison with calcification of the epiphyseal growth plate cartilage. ALP activity was not identified in the tracheal cartilage in the course of calcification, which therefore differed from that in the growth plate. The tracheal cartilage matrix was not resorbed or invaded by type I collagen during calcification. This suggests that no osteogenesis is involved in calcification of the cartilage. Immunoreactivity for type II collagen became weaker in the central region of the tracheal cartilage during development. No net loss of proteoglycans was identified with Alcian blue staining after calcification of the tracheal cartilage. Immunoreactivity for chondroitin 4-sulphate increased in the calcified tracheal cartilage, while reactivity for chondroitin 6-sulphate was weaker in the calcified area than in the surrounding uncalcified region of the tracheal cartilage. The alteration of the extracellular matrices during development may be involved in the calcification of the rat tracheal cartilage.

[Studies on toxicity of hydrocortisone 17-butyrate 21-propionate -4. Chronic toxicity in rats by subcutaneous administration (author's transl)].

Chronic toxicity of hydrocortisone 17-butyrate 21-propionate (HBP), a new synthetic corticosteroid, was studied in rats. HBP was subcutaneously injected to rats as the daily doses of 0.001, 0.01, 0.01, 1.0 and 3.0 mg/kg for 6 months, and the following recovery test was carried out for 4 weeks. Hydrocortisone 17-butyrate (HB) and betamethasone 17-valerate (BV) were used as the reference drugs at the doses of 0.1, 1.0 and 3.0 mg/kg. The suppression of body weight gain by the administration of HBP was observed at the doses more than 1.0 mg/kg in male and more than 0.1 mg/kg in female, and the dead animals were sent at the highest dose of HB and BV. Mainly at the doses more than 0.1 mg/kg HBP induced the dose-dependent symptoms such as decrease in the number of white blood cells and total protein level in serum, and increase in total cholesterol, GOT and GPT level in serum, and atrophic changes of adrenals, lymphatic tissues, skin and subsexual organs. No usual abnormality was recognized at the doses less than 0.01 mg/kg of HBP. These symptoms were more toxic in male, and the strength of toxicity was in the order of BV greater than HB greater than HBP. Many of these findings have known as common effects of corticosteroids. The changes observed in this study were almost recovered after withdrawal of HBP at the doses less than 0.1 mg/kg. As the result, it was suggested that the maximum non-toxic dose of HBP was 0.001 mg/kg.