Kijuro Obara

Presence of Cortisol-Binding Protein in the Lens

The authors have verified the presence of cortisol-binding protein in the rat lens, using gel filtration and cortisol-4-[14C]. Two methods of isolation of the cortisol-binding protein were

Further Studies on the Cortisol-Binding Protein in the Lens

The cortisol binding capacity was decreased by trypsin digestion of the lens protein. The binding capacity was decreased by the addition of 8.0 m of urea and restored partially by dialysis, suggesting

Study on the Conjugation of Cortisol in the Lens

Sulphate and glucuronide conjugation of cortisol in the normal human, cataractous, bovine, rabbit and rat lens in vitro have been investigated using a cortisol-4–14C. The authors have verif

Effect of actinomycin D or puromycin on microsomal testosterone hydroxylase activity enhanced by testosterone in female rat liver.

The injection of testosterone propionate for 4 successive days into female rats resulted in an increase of the in vitro conversion of the hydroxylated testosterones from testosterone by the hepatic microsomal, fraction, but no change in the content of microsomal cytochrome P-450 occurred. Actinomycin D or puromycin, which was administered for 4 days with injections of testosterone propionate, prevented the enzyme induction.

Separation of non-melatonin antiovulatory substances from bovine pineal powder by ultrafiltration

An attempt was made to partially separate substances which inhibit the induced ovulation by PMS and hCG in immature mice from the sodium borate buffer extract of bovine pineal powder by means of ultramembrane filtration. The antiovulatory activities were concentrated in fractions which possess materials of a molecular weight greater than 10,000 and also in fractions containing substances of a molecular weight less than 1000. The proteinaceous large inhibitor was thermostable while the small inhibitor, which is different from melatonin or arginine vasotocin, was inactivated by heating.

Biochemical studies on the pathogenesis of steroid cataracts, with particular reference to the pituitary-adrenal-liver axis

Abstract Factors having an effect on the binding and inactivation of [4- 14 C] cortisol in the rat lens, such as hypophysectomy, adrenalectomy, dexamethasone phosphate administration and liver impairment were investigated. Furthermore, the effects of flavin adenine dinucleotide on the cortisol-binding capacity in the lenses of adrenalectomized rats and of dexamethasone phosphate-treated rats were also investigated. The authors found that cortisol-binding by lens protein and sulphate conjugation of cortisol in the lens are greatly influenced by the pituitary-adrenal-liver axis. A decrease in the cortisol-binding capacity in the lens of adrenalectomized rats was slightly prevented by flavin adenine dinucleotide administration. A similar result was found in the lenses of rats treated with dexamethasone phosphate, suggesting that riboflavin may influence the inactivation of steroid hormone in the lens.

Studies on the Inactivation of Cortisol-4-[14C] in the Lenses of Liver-Impaired Rats

Changes in inactivation mechanisms of cortisol, such as cortisol-binding by protein or sulphate and glucuronide conjugation in the lenses of normal and liver-impaired rats, have been studied in order to determine the role of liver in the pathogenesis of steroid cataracts. The cortisol-binding capacity of the rat lens decreased when the liver was impaired by intraperitoneal administration of carbon tetrachloride. Sulphate conjugation of cortisol-4-[14C] showed similar results, however, no significant difference was found in glucuronide conjugation. These results indicate that there is a close relationship between inactivation of steroid hormone in the lens and liver function, and that liver dysfunction in patients receiving long-term oral corticoid therapy plays an important role in causing the onset of steroid cataracts.

In vitro metabolism of 4-14C-testosterone by thymus of male rats of various ages

Stoffwechseluntersuchungen von 4-14C-Testosteron wurden in vitro mit Thymushomogenaten, die aus 2, 3, 4, 5, 7 und 10 Wochen alten männlichen Ratten gewonnen wurden, durchgeführt. Die Radiochromatogramme der Metaboliten zeigten ein gleichartiges Bild.

Inhibition of testicular androgenesis by urinary gonadotropin-inhibiting substances in rats

The effect of urinary gonadotropin-inhibiting substances (GIS) on the androgen synthesis in rat testes was studied in vitro and in vivo. GIS, which was added to the incubation medium containing teased testicular tissues and injected into rats for 2 days, showed a suppressive effect on the formation of androstenedione from pregnenolone in the testis.

In vitro Studies on the Metabolism of Cortisol-4-[14C] in the Lenses of Rats during Maturation

The effects of maturation on the inactivation and degradation of cortisol-4-[14C] in the lenses of rats were investigated. Inbred Wistar strain rats were used at the 4th and 10th postnatal day for the immature stage and the 60th postnatal day for the mature stage of male rats. Differences were found in the cortisol-binding capacity in the rat lens between the immature and mature stage. No change with age was found for sulphate conjugation, whereas glucuronide conjugation was found to increase with age. The most interesting fact was that degradation of cortisol-4-[14C] by lens homogenate is carried out actively in the mature stage, whereas only the side-chain loss metabolite of cortisol-4-[14C] is detectable in immature stage. These findings suggest that there is an age difference in the metabolic pattern of cortisol in the rat lens and that this might be closely related to the induction of enzymes involved in the metabolism of cortisol during maturation.