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Biomedical subjects

H Tojo

Publications and source records attributed to H Tojo.

177 records · Page 10Linked to original sources
PubMed1981

Effects of steroid blockers on LH-induced ovulation in the domestic fowl, Gallus domesticus.

The spontaneous ovulation of hens was suppressed by daily injection of PMSG. The LH injected to overcome the block was accompanied by one of 4 compounds known to inhibit steroidogenesis at different sites in the biosynthetic pathway. A dose of 300 mg aminoglutethimide phosphate, which inhibits the conversion of cholesterol to 20 alpha-hydroxycholesterol, blocked the LH-induced ovulation and prevented the normal rise in plasma progesterone. Metyrapone, an inhibitor of 11 beta-hydroxylase, and SC 12937 and AY 9944, inhibitors of cholesterol synthesis, did not prevent ovulation or the progesterone rise induced by exogenous LH. Administration of progesterone overcame the inhibitory effect of aminoglutethimide, and it is suggested that progesterone is involved in the ovulatory process of the fowl.

Aminoglutethimide↗
PubMed1980

Vibrational modes of flavin bound to riboflavin binding protein from egg white. Resonance Raman spectra of lumiflavin and 8-substituted riboflavin.

The resonance Raman (RR) spectra of 8-halogenated-riboflavin, 8-demethyl-riboflavin(8-H-RF), 8-amino-riboflavin(8-NH2-RF), 8-methoxy-riboflavin(8-OCH3-RF), lumiflavin, and 3-methyl-lumiflavin were observed. The Raman lines with the highest frequency are at 1624, 1620, and 1615 cm-1 for 8-chloro-riboflavin, 8-bromo-riboflavin, and 8-iodo-riboflavin, respectively. This systematic shift confirms that the 1631 cm-1 line of riboflavin is derived from the benzene part of isoalloxazine. Substitution at the 8-position by an amino or methoxy group, which has a large influence on the electronic structure of isoalloxazine, changes the RR spectrum markedly in comparison with that of 8-halogenated riboflavin. The 1583 cm-1 line of riboflavin, which involves the vibrational displacement of N(5) and C(4a) atoms of isoalloxazine, is shifted to the low frequency side by substitution at the 8-position with an amino or methoxy group. The corresponding line of 8-H-RF, on the contrary, shifts to the high frequency side. The RR spectrum of lumiflavin is very different from that of riboflavin in the range from 1200 to 1300 cm-1. Although the pi-electronic structure is little affected by the substitution at the 10-position, the Raman spectrum of lumiflavin in this region is very sensitive.

Binding Sites↗
PubMed1980

Resonance Raman spectra of semiquinone forms of flavins bound to riboflavin binding protein.

The resonance Raman (RR) spectra of semiquinones of complexes of riboflavin or 8-methoxyriboflavin (8-OCH3-RF) with riboflavin binding protein (RBP) were observed. The RR spectrum of neutral semiquinone of riboflavin-RBP complex in H2O solution has an intense line at 1617 cm-1, not observed for oxidized riboflavin bound to RBP. The line at 1617 cm-1 does not shift in D2O solution. The absorption spectrum of semiquinone of 8-OCH3-RF bound to RBP has maxima at 586, 396, and 344 nm, and the RR spectrum doublet lines at 1623 and 1615 cm-1. In D2O solution, the 1623 cm-1 line does not shift, but the 1615 cm-1 line shifts to 1604 cm-1. The line around 1620 cm-1 for the flavin semiquinone will be useful in the determination of the redox state of flavin.

Binding Sites↗
PubMed1980

Effects of environmental temperature on the concentration of serum estradiol, progesterone, and calcium in maturing female domestic fowl.

The effects of environmental temperature on serum estradiol, progesterone, and calcium concentration in White Plymouth Rock pullets were investigated from 12 to 24 weeks of age. Pullets were grown from 10 weeks of age in individual cages at constant environmental temperatures of 13 C, 25 C, or 35 C. Serum estradiol land progesterone concentrations were measured by the use of radioimmunoassay. Serum calcium was measured by an atomic absorption spectrophotometer. There were no significant differences in growth rate or concentration of serum estradiol, progesterone, or calcium between pullets kept at 13 C and 25 C. There was a marked increase in serum estradiol and calcium concentration before onset of lay. There were high correlations between serum estradiol and calcium concentration in pullets kept at 13 C (r = .803) and 25 C (r = .813). Progesterone concentration in pullets kept at 13 C and 25 C reached a peak at 20 weeks of age. By contrast, pullets kept at 35 C had significantly lower growth rates and lower concentrations of serum estradiol, progesterone and calcium than those kept at the other two environmental temperatures. The high environmental temperature of 35 C inhibited growth and delayed sexual maturation of pullets.

Animals↗
PubMed1976

Inhibition of multiple ovulation in hypophysectomized hens treated with gonadotrophins.

Administration of PMSG or FSH to hypophysectomized hens prevented the multiple ovulation (2-3 ova) induced by an OIH. Inhibition of multiple ovulation did not occur when FSH was injected 1/2-2 hr before the OIH injection. The results are believed to support the theory that withdrawal of FSH stimulation sensitizes a follicle to the OIH in the normal hen.

Animals↗
PubMedDate not supplied

Establishment of a novel embryonic stem cell line by a modified procedure.

To generate mutant mice, embryonic stem (ES) cells are used as a vehicle for introducing mutations. The establishment of ES cells is difficult because it requires specific skills and it is time-consuming. We established a novel ES cell line derived from hybrid mice between C57BL/6 and DBA/2 using a modified method. To collect a large number of preimplantational embryos, we collected embryos at the 8-cell stage and cultured them to blastocysts, whereas the usual procedure of preparing the delayed blastocysts demands technical skills. To eliminate unnecessary female cells at an initial stage of inner cell mass culture, male clones were selected by polymerase chain reaction to detect the mouse Sry gene. The established ES cell line efficiently contributed to the germ-line when injected into 8-cell embryos of ICR mice. This potency was maintained after manipulation throughout gene targeting.

Animals↗
PubMedDate not supplied

Effect of fluvastatin, an inhibitor of 3-hydroxy-3-methyl glutaryl CoA reductase, on drug-metabolizing enzymes in rats.

Fluvastatin (FV), a new cholesterol-lowering agent, has been studied for its effects on hepatic microsomal drug-metabolizing enzymes in male rats. FV was orally administered in dosages of 1, 5, and 30 mg/kg/day for 7 consecutive days. 3-Hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase activities were markedly decreased at all dose levels. The amount of microsomal protein and the contents of cytochromes P450 and b5 did not change. No induction of aniline hydroxylase, aminopyrine N-demethylase, testosterone hydroxylases (15 alpha-, 7 alpha-, 6 beta-, 16 alpha-, and 16 beta-), and UDP-glucuronosyltransferase were found. On the other hand, 7-ethoxycoumarin o-deethylase activity was slightly increased and lauric acid omega-1-hydroxylase activity tended to be decreased after treatment with FV.

Animals↗
PubMedDate not supplied

Changes of plasma levels of human growth hormone with age in relation to mammary tumour appearance in whey acidic protein/human growth hormone (mWAP/hGH) transgenic female and male mice.

Plasma levels of human growth hormone (hGH) were determined in female and male transgenic mice with human growth hormone fusion gene driven by the promoter of mouse whey acidic protein (mWAP/hGH) at 3, 6 and 9 months of age and at mammary tumour appearance. In female transgenic mice developing mammary tumours, the plasma hGH level decreased markedly upon tumour appearance, which was associated with little change in body weight. In contrast, the hGH level changed little in transgenic male mice with tumours. In female and male transgenic mice without mammary tumours, the pattern of the change of hGH levels was variable; some showed high levels at all three time points (3, 6, and 9 months) and others had none or high levels at one or two time points.

Age Factors↗
PubMedDate not supplied

Histology, immunohistochemistry, and ultrastructure of hydropericardium syndrome in adult broiler breeders and broiler chicks.

Ten 250-day-old broiler breeders, seven 16-day-old broiler chicks, and three 25-day-old broiler chicks suffering from hydropericardium syndrome (HPS) in Japan were examined histologically, immunohistochemically, and ultrastructurally. Clinically, the chickens died suddenly without apparent signs. The mortality rates were 6.4%, 20.2%, and 26.1%, respectively. The common characteristic histologic lesion was necrosis of hepatocytes, accompanied by intranuclear inclusions of hepatocytes and hemorrhages. In the spleen, there were activation of macrophages in splenic sinus and ellipsoids and erythrophagocytosis in the splenic sinus. The interlobular interstitium of the lung showed marked edema. The air and blood capillary areas of parabronchi included many macrophages with yellow pigments. With immunoperoxidase staining, intranuclear inclusion bodies within degenerating hepatocytes stained positively for group I adenovirus antigen. Ultrastructurally, numerous viral particles (65-70 nm in diameter) were demonstrated in the intranuclear inclusions of hepatocytes. Group I adenovirus (serotype 4) was isolated from liver samples of adult broiler breeders and broiler chicks with HPS. This study suggests that HPS may be caused by group I adenovirus.

Animals↗