Age and sex differences in the metabolism of C19-delta5-steroids in human amniotic epithelium

In vitro transformation of [4-(14)C]-dehydroepiandrosterone and [4-(14)C]-5-androstenediol in human amniotic epithelium from the first and the second trimester was studied. Total conversion of both substrates used and formation of their "more polar" metabolites increased with advancing gestational age. The reduction of 17-oxo or the oxidation of 17 beta-hydroxy groups reached a maximum between weeks 17 and 20. A significant decrease in the conversion of delta 5-3 beta-hydroxy group from week 11 was evident. No significant sex differences were observed.     

Role of human adipose tissue in the production and metabolism of steroid hormones

Radioimmunological methods have been employed for the simultaneous determination of dehydroepiandrosterone, androstenedione, testosterone, oestrogens (oestradiol + oestrone), progesterone, 17 alpha-hydroxyprogesterone and cortisol in human adipose tissue and peripheral blood to compare the hormone pool of adipose tissue with that in the general circulation. Extremely high steroid concentrations in the adipose tissue and hormone pool in the fat of obese subjects were observed. For adipose tissue/serum steroid ratios, the highest values were obtained for dehydroepiandrosterone and the lowest ones for cortisol. A preliminary study showed a great accumulation of steroids in adjacent adipose tissue of breast tumors. Striking differences were observed in the adipose tissue steroid concentrations between benign and malignant mammary tumors. The present findings revealed that blood hormone determinations may be insufficient to consider the steroid hormone availability in various endocrinopathies or steroid responsive tumors, especially when the endocrine state of extremely obese subjects is observed.     

Anabolic steroid metabolism in skeletal muscle

Three hundred and sixty male albino rats weighing 180 to 200 g were used to determine the effect of anabolic steroid hormones on adaptive changes in the synthesis of ribosomal RNA both in sedentary animals and in animals involved in a training programme. One injection of Retabolil (0.1 mg/100 g body weight) increased the α-amanitin insensitive RNA polymerase activity of nuclei from skeletal muscles. Fourteen h after this hormone injection the enzyme activity was 45% higher than in control animals and it remained at this level for 4 days. Under these conditions a selective binding of 19-nortestosterone with cytoplasmic proteins of skeletal muscle was found. Physical training increased the RNA polymerase activity by 50% (P < 0.05). It was found that the testosterone binding capacity of a cytoplasmic extract from trained animals was 70% greater than that of the control animals (P < 0.05). Four injections of Retabolil during training resulted in an additional increase of RNA polymerase activity of 40% (P < 0.05) but reduced the testosterone binding capacity of the cytoplasmic proteins that occurred with training by 21%. These results demonstrate the effect of anabolic hormones in the regulations of RNA synthesis in skeletal muscle nuclei in the process of their adaptation to systematic physical training.     

Identification of cells from fetal bladder epithelium in human amniotic fluid

Summary Cultured human amniotic fluid cells consist of five different types of cytokeratin-positive epithelial cells, E-1 to E-5, differing by their size, growth morphology, and cytokeratin pattern, according to our earlier investigations. Using anticytokeratin antibodies in indirect immunofluorescence (IIF) microscopy, we show in this study that cultured urine cells contain four of the cell types found in amniotic fluid. In addition, we used two urothelium-specific antibodies, anti-UMA and anti-Las-86, in combination with cytokeratin antibodies to distinguish urothelium-derived cells in amniotic fluid and urine cell cultures. Two of the epithelial cell types were found to express urothelial antigens and thus to originate from the transitional bladder epithelium. These cells were found in 26 of the 33 amniotic fluid cell cultures and in nine of the ten urine cell cultures.     

Immunocytochemical analysis of the cytoskeleton of the human amniotic epithelium

Summary The amniotic epithelium constitutes a diffusion barrier controlling the passage of solutes and water between the aminotic cavity and maternal circulation. With the present immunocytochemical approach, we have shown that several major components of the cytoskeleton, i.e., actin, -actinin, spectrin and ezrin, are preferentially associated with the apical and lateral cell surfaces of the human amniotic epithelium. Keratins are distributed throughout the entire cytoplasm, whereas vimentin mainly forms a perinuclear scaffold. These findings indicate a role of the various components of the cytoskeleton in the structural integrity and modulation of cell shape and junctional permeability.     

Pituitary control of hepatic steroid metabolism

Hypophysectomy of male animals has little effect on the hepatic 4-androstene-3,17-dione (androstenedione) metabolism except at the kinetic level where changes in the apparent Km of the 16 alpha- and 7 alpha-hydroxylases are seen. On the other hand, hypophysectomy of female animals leads to a "masculinization" of hepatic androstenedione metabolism, following the changes seen in Vmax of the respective enzymes probably due to the removal of the source of "feminizing factor" thought to maintain the female-type metabolism in the liver. There seems to be a temporal dissociation of the effects on the various enzymes indicating different cellular control mechanisms for these enzymes. Oestrogen treatment of male rats causes "feminization" of the hepatic androstenedione metabolism. The time study shows an initial increase in 17-hydroxysteroid oxidoreductase, 6 beta- and 16 alpha-hydroxylase activities followed by a decrease to the levels of females. This biphasic effect is possibly due to an initial direct effect of the oestrogen on the liver followed by an indirect effect via the hypothalamo-pituitary system. The changes in enzyme activity noted are related to changes in Vmax of the respective enzymes although changes in apparent Km are also seen.     

The significance of steroid metabolism in human cancer

Epidemiological and clinical evidence suggests that steroid hormones are intimately involved in the natural history of many cancers, including those of the breast, endometrium and prostate. However, it has been difficult to demonstrate that progressive changes in tumour development are related to circulating levels of steroids. This may be because further metabolism of steroids occurs locally within the tumour and its adjacent host tissue. Using the breast as an example, data has been reviewed that such local metabolism may (a) markedly change the biological potency of steroid hormones and (b) be associated with the risk, presence, pathology, stage and hormone sensitivity of cancer. The implications of these findings are discussed including the need to identify factors which regulate steroid metabolism in peripheral tissue and tumours. In this way the potential to influence the microenvironment around and within tumour cells may be realized in favour of the patient.     

A comparison of lyophilized amniotic membrane with cryopreserved amniotic membrane for the reconstruction of rabbit corneal epithelium

Many researchers have employed cryopreserved amniotic membrane (CAM) in the treatment of a severely damaged cornea, using corneal epithelial cells cultured on an amniotic membrane (AM). In this study, two Teflon rings were made for culturing the cells on the LAM and CAM, and were then used to support the AM, which is referred to in this paper as an Ahn’s AM supporter. The primary corneal epithelial cells were obtained from the limbus, using an explantation method. The corneal epithelium could be reconstructed by culturing the third-passage corneal epithelial cells on the AM. A lyophilized amniotic membrane (LAM) has a higher rate of graft take, a longer shelf life, is easier to store, and safer, due to gamma irradiation, than a CAM. The corneal epithelium reconstructed on the LAM and CAM, supported by the two-Teflon rings, was similar to normal corneal epithelium. However, the advantages of the LAM over that of the CAM make the former more useful. The reconstruction model of the corneal epithelium, using AM, is considered as a goodin vitro model for transplantation of cornel epithelium into patients with a severely damaged cornea.