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T Yuasa

Publications and source records attributed to T Yuasa.

At least 199 records · Page 11Linked to original sources
PubMed1989

[The metabolism of glucose monitored by 13C-NMR in the gerbil brain in vivo-natural course and application to the ischemic model].

Glucose metabolism is altered in various pathologic conditions in the brain, i. e. ischemia, epilepsy and hypoglycemia. Therefore, analysis of glucose metabolism in pathologic conditions needs careful investigation of that in steady state. 13C-NMR method allows continuous sequential monitoring of changes in metabolism of glucose in vivo. The natural abundance of 13C is quite low (1.1%) and by administering 13C labelled in various skeleton in glucose, it is possible to monitor the metabolites in vivo. In this study, 13C glucose labelled in 1-position of carbon was employed to investigate the metabolic pathways in the control and transient ischemic gerbil brain with reperfusion. Male mongolian gerbils weighing 60-80 g were employed in this study. The gerbils were anesthetized by intraperitoneal administration of pentobarbital. The right skull was exposed and a surface coli was placed directly above the skull bone. After the operation, the animals were fastened to the NMR probe vertically. 500 mg/kg of [1-13C] glucose was injected via femoral catheter. 13C-NMR spectra were serially obtained before and after injection with GX-270 NMR spectrometer (JEOL, Tokyo, Japan, 6.34 T). In other series of experiments, 30 minutes of cerebral ischemia were induced after 15 minutes of glucose injection by the bilateral common carotid artery occlusion. In the normal gerbil brain, after administration of [1-13C] glucose (500 mg/kg), alpha and beta-anomers of [1-13C] glucose peak appeared abruptly and reached its peak level at 7.5-15 min acquisition period. The C2 peak representing glutamate and/or glutamine appeared later. The C3 and C4 peak started to appear even later at 30-40 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[The observation of blood-brain barrier of organic mercury poisoned rat: a Gd-DTPA enhanced magnetic resonance study].

Permeability of the blood-brain barrier (BBB) of methylmercury chloride (MMC) intoxicated rat brain was studied in vivo by gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) enhanced magnetic resonance imaging (MRI), measuring the longitudinal relaxation time (T1) and the transverse relaxation time (T2). MMC intoxicated rat brain showed the prolonged T1 in the cerebral white matter and prolonged T2 in the cerebellar cortex. After Gd-DTPA administration, T1 of cerebral and cerebellar white matter shortened from 1.647 to 1.344 sec., and 1.290 to 1.223 sec. respectively. On the contrary, T2 showed no change after Gd-DTPA injection. It was concluded that, although the shortening of T1 after Gd-DTPA enhancement was rather little when compared with experimental brain ischemia, the shortening of the relaxation time of the MMC intoxicated rat brain was caused by the increased permeability of BBB.

Animals↗
PubMed1988

Biochemical analysis of decreased ornithine transport activity in the liver mitochondria from patients with hyperornithinemia, hyperammonemia and homocitrullinuria.

Hyperornithinemia, hyperammonemia and homocitrullinuria (HHH disorder) is an inherited metabolic disorder which shows peculiar amino acid changes in the serum and urine. The primary defect is considered to be the transport of ornithine across the mitochondrial membrane, but there is no direct evidence for this so far. We have analyzed ornithine transport activities in the liver mitochondria from three patients with HHH disorder. In coupled liver mitochondria we demonstrated low activities of citrulline synthesis and low rates of ornithine uptake. However, there were no abnormalities in carbamoyl-phosphate synthetase activity, ornithine carbamoyltransferase activity, N-acetylglutamate levels or O2 uptake with succinate. We also performed a kinetic study of citrulline synthesis as a function of ornithine concentration. We found increased Km values for ornithine and varied Vmax values of citrulline synthesis, which suggested the presence of a mutant transport protein. From these results we conclude that the defect of hyperornithinemia, hyperammonemia and homocitrullinuria lies in the transport of ornithine across the mitochondrial membrane.

Amino Acid Metabolism, Inborn Errors↗
PubMed1988

Upstream region of hepatitis B virus S gene responsible for transcriptional stimulation by dexamethasone.

Transcriptional regulation of hepatitis B virus (HBV) surface antigen (HBs Ag) gene was studied in human hepatoma-derived cell lines. Treatment with dexamethasone (Dex; 1 microM) induced an increase in the smaller HBs-mRNA initiated within Pre-S region encoding S and Pre-S2 proteins, but not the larger HBs-mRNA initiated in the further upstream encoding Pre-S1 protein. The Bg1II-MstII fragment (map position 2425-3201) in the upstream of the S gene was used as a transcriptional promoter of chloramphenicol acetyltransferase (CAT) gene. The CAT activity brought about by this construct in the transient assay was elevated by 5-fold in the presence of Dex. Deletion analysis localized the sequence required for the full response to Dex within a 590-base pair fragment in the upstream of the transcriptional initiation site of the smaller HBs-mRNA. And this fragment contained the binding site for the nuclear factor I (NF-I), which might have some role in Dex-dependent transcriptional stimulation.

CCAAT-Enhancer-Binding Proteins↗
PubMed1988

X-linked ichthyosis and ichthyosis vulgaris: comparison of their clinical features based on biochemical analysis.

Thirty cases of X-linked ichthyosis (XLI) and 32 cases of ichthyosis vulgaris (IV) were diagnosed by measuring the steroid sulphatase activity of peripheral blood lymphocytes or the electrophoretic mobility of serum LDL or both. The clinical features of the two conditions were then compared. In both diseases 60-66% of patients had a family history of the condition. Ichthyosis was noted at birth or immediately afterwards in 59% of the patients with XLI while it appeared in infancy in 68% of those with IV. Scales were mostly large and brown or dark brown in patients with XLI, while the majority of patients with IV had small brown or light brown scales. The distribution of the ichthyotic lesions differed in the two types of ichthyosis. On the trunk, the abdomen was more severely involved than the back in 63% of the cases with the XLI, whereas the back was more scaly than the abdomen in 44% of those with IV. On the extremities, the extensor surface was more severely affected than the flexor surface in both types. X-linked ichthyosis was characterized by the presence of lesions in the pre-auricular area, which were found in 93% of the cases with XLI, while only 17% of the IV patients had ichthyotic lesions at this site. Involvement of the preauricular area could be an important clinical feature for distinguishing XLI from IV.

Adolescent↗
PubMed1987

Antibody to sialosyllactosaminylparagloboside in a patient with IgM paraproteinemia and polyradiculoneuropathy.

Serum from a patient with IgM paraproteinemia and polyradiculoneuropathy, diagnosed as malignant lymphoma, reacted specifically with a ganglioside, sialosyllactosaminylparagloboside (SLPG), in human peripheral nerve but not with myelin-associated glycoprotein (MAG). This finding demonstrates the existence of anti-SLPG antibody in the patient's serum, suggesting that this antibody may play a role in the pathogenesis of neuropathy.

Aged↗
PubMed1987

Hyperornithinemia, hyperammonemia, and homocitrullinuria: case report and biochemical study.

Two siblings with hyperornithinemia, hyperammonemia, and homocitrullinuria are reported. The clinical picture included protein intolerance, mental retardation, seizures, and stuporous episodes. One patient had cerebellar ataxia, myoclonus, convulsive seizure, and muscular weakness in both legs. Isolated liver mitochondria in the patient revealed that ornithine transport and citrulline synthesis were decreased, but urea cycle enzymes and ornithine aminotransferase were normal. Ornithine metabolism was decreased in cultured skin fibroblasts.

Adolescent↗