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Biomedical subjects

H Obata

Publications and source records attributed to H Obata.

At least 181 records · Page 10Linked to original sources
PubMed1989

[Effect on uptake of D-glucose, L-leucine and L-leucylglycine into intestinal brush border membrane vesicles isolated from rats fed either oligopeptide or amino acid elemental diet].

The uptake of D-glucose, L-leucine and L-leucylglycine into intestinal brush border membrane vesicles isolated from rats was investigated. They were fed either oligopeptide (SP group) or amino acid (AA group) elemental diets for four weeks. The results are as follows. As for L-leucine uptake, there was no significant difference in Km value between SP group and AA group. But Jmax value of SP group is significantly 1.7 times as large as that of AA group. As for L-leucylglycine uptake, there was no difference in Km value between the two groups, but Jmax value of SP group is significantly about twice as large as that of AA group. There is however, no difference in Km value and Jmax value between the both groups. These results indicate that L-leucine and L-leucylglycine transport carriers in the brush border membrane significantly increased in SP group compared with that in AA group, and that these carriers might be induced by oligopeptides as intraintestinal substrate.

Amino Acids↗
PubMed1988

Purification and properties of 4-hydroxycyclohexanecarboxylate dehydrogenase from Corynebacterium cyclohexanicum.

4-Hydroxycyclohexanecarboxylate dehydrogenase, which requires NAD as a cofactor, was detected in crude soluble extracts of Corynebacterium cyclohexanicum grown on cyclohexanecarboxylic acid as the sole carbon source. The dehydrogenase was purified from extracts to an electrophoretically homogenous state by ammonium sulfate precipitation and chromatography on DEAE-650s, agarose-NAD and hydroxyapatite. The enzyme consisted of two identical subunits and had a native relative molecular mass of 53,600. There were two residues each of cysteine and tryptophan in the enzyme molecule. Oxo acid rather than hydroxy acid was routinely used as substrate for assay of the enzyme. The enzyme is highly specific for 4-oxocyclohexanecarboxylic acid: the carboxyl group is essential and the position of carbonyl group is important; neither the 2-oxo nor the 3-oxo homologue was used as substrate. A methyl substitution on the ring of 4-oxocyclohexanecarboxylate resulted in an almost complete loss of its activity. The reduction product was identified as trans-4-hydroxycyclohexanecarboxylic acid by gas-liquid chromatography and mass spectrometry. It was used as a substrate for the reverse reaction in the presence of NAD but not its cis-isomer. The enzyme was specific for the B-side (pro-S) hydrogen of NADH in the hydrogen transfer from NADH to 4-oxocyclohexanecarboxylate. The Km values for 4-oxocyclohexanecarboxylate and NADH in the reduction reaction at pH 6.8 were 0.50 mM and 0.28 mM, respectively, whereas those for trans-4-hydroxycyclohexanecarboxylate and NAD in the oxidation reaction at pH 8.8 were 0.51 mM and 0.23 mM, respectively. The equilibrium constant of the reaction was 1.79 x 10(-10) M. The enzyme was strongly inhibited by N-bromosuccinimide.

Alcohol Oxidoreductases↗
PubMed1988

Suppression of hepatitis B antibody synthesis by factor made by T cells from chronic hepatitis B carriers.

Mononuclear cells taken from subjects who had been immunised with hepatitis B vaccine could be stimulated by pokeweed mitogen plus hepatitis B surface antigen to synthesise antibody to hepatitis B surface antigen in vitro. Such synthesis was suppressed by supernatants of cultures of T cells from hepatitis B surface antigen carriers. The suppressor activity of this soluble factor in the supernatants was specific for anti-HBs since it did not affect production of polyclonal immunoglobulins or specific antibody to tetanus toxoid and since its effect was completely absorbed by a hepatitis B surface antigen column. The suppressor factor was made by T-cell cultures but not by non-T-cell cultures. T-cells for 13 out of 15 carriers produced this factor.

Carrier State↗
PubMed1988

Glucose intolerance and pancreatic endocrine dysfunction in dogs with obstructive jaundice.

Mechanisms involved in pancreatic endocrine disturbances in the presence of obstructive jaundice were studied in mongrel dogs with a ligated bile duct. Slower disappearance rate of glucose (KG) and lower portal insulin responses within ten minutes following intravenous glucose loading were observed in jaundiced dogs than in the controls. Hyperglucagonemia in the portal vein was evident in jaundiced dogs for five weeks. Morphometrical analysis of the beta-cells showed that the volume density of secretory granules decreased in jaundiced dogs. However, in three types of beta-granules, the change of size was observed only in the bar-shaped core granules. The volume density of the rough endoplasmic reticulum increased whereas that of the Golgi apparatus decreased in jaundiced dogs for five weeks. In contrast with beta-cells, alpha-cells revealed no morphological changes in any groups. These findings suggest that the beta-granules fail to mature if there is an inhibition by a blockade of energy-requiring steps such as the ER-Golgi transfer system. Impairment of beta-granules is considered to lead to glucose intolerance. Hyperglucagonemia is probably secondary to abnormal beta-cell function, which causes insulin deficiency and the loss of the relation between alpha-cells and beta-cells.

Animals↗
PubMed1988

Deposition velocity of gaseous I to rice grains.

Among the routes of gaseous I transfer to rice grains, direct deposition to the hull of rice plants and the subsequent transfer to brown rice and polished rice should be more critical than leaf absorption-translocation. A grain number normalized deposition velocity (Vs) is recommended as a key parameter to assess the amount of gaseous I deposited on the rough rice. This parameter is given as "iodine content per unit number of grain per unit time" divided by "iodine concentration per unit volume of the air." After the heading period the surface area of rough rice is almost constant but weight increases with time. Therefore, mass normalized deposition velocity (VD) varies with time. By introducing Vs instead of VD, the variations could be converged into narrow ranges. The contribution of gaseous I from the atmosphere to rough rice, brown rice and polished rice were estimated using Vs values obtained experimentally and gaseous I concentration in the air.

Air Pollutants↗
PubMed1988

Nature of immunological non-responsiveness to hepatitis B vaccine in healthy individuals.

This study was undertaken in order to analyse the immuno-regulatory mechanism of non-responsiveness to hepatitis B (HB) vaccine in healthy individuals. We have reported already that peripheral mononuclear cells (MNC) isolated from anti-HBs sero-positive subjects after booster injection are able to make anti-HBs in vitro by stimulation with pokeweed mitogen (PWM) plus HBsAg. In contrast, under the same conditions, non-responder (NR) MNC failed to produce anti-HBs in vitro, even after an additional injection, although an amount of immunoglobulin was synthesized corresponding with the responder controls. Co-culture experiments carried out with T-cell fractions (T) and non-T-cell fractions (NT) from NR and controls showed: (i) by Week 2 after the last vaccination, NT from NR could hardly be activated to produce anti-HBs; however, by Week 4 significant synthesis of anti-HBs was induced by the stimulation of responder T; (ii) in experiments using responder NT and T from NR, seven out of eight and five out of nine co-cultures were found to make anti-HBs by Weeks 2 and 4, respectively; (iii) T from NR, as well as their culture supernatants, specifically suppressed anti-HBs production of responder MNC, especially by Week 4 after the last vaccination. From these results, it is predicted that the early stage of non-responsiveness in NR is mainly due to a defect of the B-cell repertoire, while that of the late stage is caused by the existence of HBsAg-specific suppressor T cells.

Adult↗
PubMed1987

A 29 kDa GTP-binding protein expressed in mouse brain, lung, kidney, spleen and transformed NIH3T3 cells.

A novel 29 kDa GTP-binding protein has been detected in mouse brain, kidney, lung and spleen. The binding property is specific for guanine nucleotides, and the binding activity for GTP is retained after transfer of the 29 kDa protein to a nitrocellulose membrane. The 29 kDa protein is also expressed in NIH3T3 cells transformed by activated human c-Ha-ras, hst, ret and c-raf. The 29 kDa protein present constitutively in some mouse tissues is possibly involved in some cellular signal transduction relevant to the function of these tissues. In addition, its function may play a role in phenotype of transformed cells.

Animals↗
PubMed1987

Production of abnormal prothrombin (des-gamma-carboxy prothrombin) by hepatocellular carcinoma. A clinical and experimental study.

We measured plasma abnormal prothrombin (des-gamma-carboxy prothrombin; DCP) levels in normal subjects and in patients with hepatocellular carcinoma and other various diseases using the enzyme-linked immunosorbent assay developed by Motohara et al. (Pediatr Res 1985; 19: 354-357). Fifty-eight percent of 52 patients with hepatocellular carcinoma had elevated DCP levels; 24 of 28 patients with advanced or moderately advanced hepatocellular carcinoma were positive. By contrast, 50 normal controls, 13 pregnant women and 10 patients with acute hepatitis had normal levels. Three of 55 patients with chronic liver disease, and 6 of 32 patients with other malignancies, showed a slight increase. Thus, increased plasma DCP appears useful for the diagnosis of hepatocellular carcinoma. To elucidate the mechanism for the increase of DCP in hepatocellular carcinoma, we cultured a human hepatoma cell line, huH-2, and measured the levels of this abnormal prothrombin in the medium. The huH-2 cells produced large amounts of DCP in the medium without added vitamin K. It increased in a cell concentration- and time-dependent fashion. These cells produced no detectable amount of DCP in the medium with added vitamin K. Thus, human hepatoma cell line huH-2 produces DCP, and its production is dependent on the amount of vitamin K available in the medium. Des-gamma-carboxy prothrombin may be a useful tumor marker for the diagnosis of hepatocellular carcinoma.

Biomarkers↗
PubMed1986

Esophageal lesions in intestinal Behçet's disease.

Esophageal lesions are rarely seen in patients with intestinal Behçet's disease. Three patients with esophageal lesions (dissection of esophageal mucosa, esophageal ulcer, esophageal varices) were observed among 15 patients with intestinal Behçet's disease or non-specific simple ulcer (1974-1984). Two-thirds of these fifteen patients had fully developed or suspected Behçet's disease, and one-third had no symptoms typical of Behçet's disease. They are classified as non-specific simple ulcer. The average age of the 15 patients was 43 years, all patients but one were male. The recurrence rate after surgical treatment was 70%, that of medical treatment was 90%.

Adult↗
PubMed1985

Natural history of hepatocellular carcinoma and prognosis in relation to treatment. Study of 850 patients.

A total of 850 patients with hepatocellular carcinoma seen during the last 8 years were analyzed retrospectively for survival in relation to treatment and disease stage. A new staging scheme based on tumor size, ascites, jaundice and serum albumin was used. Clearly, the prognosis depended on disease stage. The median survival of 229 patients who received no specific treatment was 1.6 months, 0.7 month for Stage III patients, 2.0 months for Stage II, and 8.3 months for Stage I. The median survival of Stage I patients who had hepatic resection (n = 115) was 25.6 months and Stage II patients with resection (n = 42) was 12.2 months. In patients who had a small cancer (less than or equal to 25% of liver area in size) the median survival was 29.0 months. Survival of the surgically treated patients, which represented a highly selected group, was better than that of medically treated patients of a comparable stage. Median survival of Stage I medically treated patients (n = 124) was 9.4 months, for Stage II (n = 290) 3.5 months, and for Stage III (n = 50) 1.6 months. Medical treatment prolonged survival in Stage II and III patients, but not in Stage I. Transcatheter arterial embolization gave a better survival compared with chemotherapy, whether intra-arterial bolus administration of mitomycin C, systemic mitomycin C, or oral/rectal tegafur, in Stage II. Among various chemotherapeutic modalities, intra-arterial bolus injection was superior to systemic chemotherapy in survival in Stage II. In Stage III, chemotherapy improved survival as compared with no specific treatment. The major causes of death were hepatic failure and gastrointestinal bleeding, probably due to the coexistent advanced cirrhosis. These results in survival are much improved over the past reports, and the differences are probably a result of earlier diagnosis and frequent hepatic resections.

Adolescent↗
PubMed1985

[Right ventricular dysplasia: clinical features compared with dilated cardiomyopathy].

Five patients with right ventricular dysplasia (RVD) and 28 patients with predominantly left sided dilated cardiomyopathy (DCM) were studied. RVD was characterised by syncope, recurrent sustained ventricular tachycardia, which typically had a left bundle branch block pattern on the surface electrocardiogram, right heart failure, and faint or absence of the right ventricular free wall on the myocardial scintigraphy. Two-dimensional echocardiographic, radionuclide angiographic, and contrast ventriculographic studies were typical of the right ventricular abnormalities in both Uhl's anomaly and arrhythmogenic right ventricular dysplasia. Two of them were died suddenly. Pathologic examinations showed "parchment-like" thinning of portions of the right ventricular free wall and its replacement by adipose tissue, although such degenerations were not found in the septum and the left ventricle. By contrast, DCM was characterised by exertional dyspnea and short run ventricular tachycardia, most of which had a right bundle branch block pattern. Ten of them had left ventricular myocardial defects on the scintigraphy, of whom five died suddenly. Hemodynamic data showed that left ventricular dysfunction was predominant more than right ventricle. Thus we postulate that these two syndromes are manifestations of a congenital, pathophysiologic process - the "involved right or left ventricle" syndrome.

Adult↗