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Biomedical subjects

Y Toyama

Publications and source records attributed to Y Toyama.

At least 181 records · Page 10Linked to original sources
PubMed1975

Studies on the circadian rhythm of phosphoenolpyruvate carboxykinase. III. Circadian rhythm in the kidney.

Phosphoenolypyruvate carboxykinase [EC 4.1.1.21] activity in rat kidney shows a circadian rhythm with the highest activity between 0200 h and 0800 h and the lowest activity between 1400 h and 2000 h. The rhythm was observed in both sexes and throughout the year. Actinomycin D and cycloheximide effectively blocked the circadian increase in enzyme activity. These findings suggest that the circadian increase in phosphoenolypyruvate carboxykinase activity is due to net synthesis of enzyme protein through newly synthesized mRNA. In experiments with kidney cortex slices, gluconeogenesis from the radioactive precursor, [14C]malic acid, was considerably higher at 0200 h than at 1400 h, varying in parallel with the change in the enzyme activity.

Acclimatization↗
PubMedDate not supplied

Delayed enhancement of hepatocellular carcinoma on dynamic CT: sign of extrahepatic collaterals after transcatheter arterial chemoembolization or transcatheter arterial chemoinfusion.

BACKGROUND: We examined the factors of delayed enhancement of hepatocellular carcinoma (HCC) on dynamic computed tomography (CT). METHODS: Dynamic CT and angiography were compared in 113 patients who had undergone transcatheter arterial chemoembolization or transcatheter arterial chemoinfusion and were suspected of developing new HCCs. RESULTS: Eight of 113 patients had HCC nodules that enhanced gradually from the arterial phase to the portal venous phase on dynamic CT and were fed by extrahepatic arteries on angiography. The feeding artery was an omental branch of the splenic artery in one lesion, an omental branch of the gastroduodenal artery in five, and the intercostal artery in two. CONCLUSION: We believe that the recurrence of HCCs delayed enhancement on dynamic CT because the hepatic artery was hidden and long narrow extrahepatic collaterals fed the tumor.

Aged↗
PubMedDate not supplied

A case of decapitated spermatozoa in an infertile man.

A case of headless or decapitated spermatozoa of an infertile man is reported. The 33-year-old patient showed almost normal spermiogram except for a high percentage (more than 90%) of headless spermatozoa. Both hypoosmotic swelling and zona-free hamster egg tests showed that most headless spermatozoa appeared to be normal in their function as tails. The ultrastructure of the ejaculated spermatozoa was observed using a surface replica method and by conventional ultrathin sectioning. The headless spermatozoa were almost normal in structure except for the absence of the head. Tailless heads were rarely observed. Varieties of ultrastructural abnormalities were observed in spermatozoa heads. Among them, abnormalities in the nuclear membrane covering the posterior pole of the nucleus were prominent. The implantation fossa and the basal plate were not formed. Instead, the nuclear membrane with numerous nuclear pores was found in this region. The decapitation seemed to take place between the region of the basal plate and the proximal centriole.

Acrosome↗
PubMedDate not supplied

A case of an infertile man with short-tailed spermatozoa.

Ejaculated spermatozoa from an infertile patient were examined by scanning and transmission electron microscopy. All spermatozoa had abnormalities in the tail region. The abnormalities were divided into three types: (a) spermatozoa with a spherical tail. The tail was larger than the head in volume. This type of abnormality accounted for about 60% of the population; (b) spermatozoa with a blunt tail. The tails were about 2 microns in diameter and about 7 microns in length. This type of abnormality accounted for about 30% of the population of an ejaculate; (c) spermatozoa without a tail. Some of these had only a rudimentary tail. About 10% of the population belonged to this type. In types A and B, all components of the tail, except for dynein arms, were observed, but they were severely disarranged. Biopsy specimens of the testes and of the nasal mucosa of this patient were also investigated. The testicular biopsy showed defects in manchette formation. Normal development of the manchette could not be observed. The nasal epithelium showed absence of the inner dynein arms in the cilia.

Adult↗