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Biomedical subjects

Y Ohta

Publications and source records attributed to Y Ohta.

At least 955 records · Page 53Linked to original sources
PubMed1986

Mode of L-tryptophan uptake into rat hepatocytes via trypsin-sensitive high-affinity transport system.

The effect of trypsin treatment on the mode of L-tryptophan uptake (L- and T-transport systems) into hepatocytes was investigated in comparison with that of L-leucine (L-type system) using isolated rat hepatocytes. L-Tryptophan uptake occurred via at least two saturable (one high-affinity and one low-affinity) and one non-saturable components in intact hepatocytes, while L-leucine was taken up via one saturable and one non-saturable component. Hepatocytes whose surface had been digested with trypsin lost only the high-affinity component of the two saturable L-tryptophan transport systems, while they retained the saturable component for L-leucine transport (Km = 3.3 mM). Km values for the trypsin-sensitive (high-affinity) and -insensitive (low-affinity) components of L-tryptophan uptake were 14 microM and 2.1 mM, respectively. However, inhibition studies with some substrates of the L-, T- and both transport systems as inhibitor demonstrated that L-tryptophan uptake via these two components could not be classified in terms of the T- and L-systems. The present results indicate the presence of a carrier with a very high affinity for L-tryptophan in rat hepatocytes.

Animals↗
PubMed1985

Complete nucleotide sequence of the E. coli N-acetylneuraminate lyase.

The nucleotide sequence of the cloned DNA, 1,243 bp in length coding for N-acetylneuraminate lyase (N-acetylneuraminate pyruvate lyase; NPL) of Escherichia coli has been determined. Nucleotide sequence and amino acid analysis have assigned the open reading frame for NPL, starting with the ATG near its 5'terminus. The molecular weight calculated from the predicted amino acid sequence was 32,640 daltons, being in good agreement with that of a NPL subunit estimated by the SDS-PAGE method and amino acid composition. Several signal sequences conserved in the promoter regions of E. coli were found in the npl gene. They were the Shine-Dalgarno sequence, the Pribnow box and the sequence coserved in the "-35 region" and they were separated to each other with preferable spacing for an efficient transcription. Downstream from the termination codon, the inverted repeat sequence was present, followed by 4 successive T's.

Amino Acid Sequence↗
PubMed1985

The effect of sulfhydryl compounds on the catalytic activity of Cu, Zn-superoxide dismutase purified from rat liver.

Sulfhydryl compounds such as reduced glutathione, cysteine and 2-mercaptopropionylglycine, a hepato-protective agent, activated Cu, Zn-superoxide dismutase purified from rat liver at low concentrations (below 10 microM). Furthermore we found evidence indicating that this activation is achieved by reducing Cu2+ present in the catalytic site of the dismutase, and thereby promoting the dismutation of superoxide anions.

Animals↗
PubMed1985

An actin-depolymerizing protein (destrin) from porcine kidney. Its action on F-actin containing or lacking tropomyosin.

An Mr 19 000 protein (destrin) that has the ability to rapidly depolymerize F-actin in a stoichiometric manner was purified from porcine kidney by sequential chromatography on DNase I-agarose, hydroxyapatite, and Sephadex G-75. Its actin-depolymerizing activity is reversibly controlled by changes in KCl concentration but is insensitive to Ca2+ concentration. The rate of depolymerization of F-actin by destrin is much faster than that of spontaneous depolymerization induced by dilution and is not markedly decreased by the addition of end-blocking reagents such as cytochalasin B. These results suggest that destrin depolymerizes F-actin by interacting directly with F-actin protomers. Binding of muscle tropomyosin to F-actin slows down the rate of destrin-induced depolymerization of F-actin by about 30-fold. The data suggest that the destrin-induced depolymerization occurs from the ends of F-actin when F-actin is complexed with tropomyosin, but it takes place from the entire length of F-actin in the absence of tropomyosin.

Actin Depolymerizing Factors↗
PubMed1985

A case of spontaneous regression of hepatocellular carcinoma with bone metastasis.

A 78-year-old Japanese man with chronic liver disease developed hypervascular liver tumors accompanied by marked elevation of alphafetoprotein value (the highest level; 26200 ng/ml) and pathologic fracture of the femur. After an operation for the fracture followed by gastrointestinal bleeding and repeated transfusions of blood, the tumors disappeared with normalization of the alpha-fetoprotein level, and the radiolucent area around the fracture site of the femur became consolidated. The necrotic tissue responsible for the fracture histologically showed an appearance of hepatocellular carcinoma. The patient survives 62 months after the initial increase in alpha-fetoprotein level. This is a case of spontaneous regression of both hypervascular liver tumors which are highly suggestive of hepatocellular carcinoma and their metastasis.

Aged↗
PubMed1985

Transcatheter arterial embolization for hepatocellular carcinoma. Benefits and limitations for unresectable cases with liver cirrhosis evaluated by comparison with other conservative treatments.

Transcatheter arterial embolization (TAE) for unresectable hepatocellular carcinoma (HCC) was performed in cirrhotic patients with nonoccluded main portal trunk and total bilirubin levels less than 5 mg/dl. In 48 patients with tumor response to TAE, its benefit was evaluated by comparing their survival with that in 28 patients after conservative treatments, matched by clinical data. In TAE-treated patients, tumor findings on computerized tomography and angiogram were significantly different between those dying within 3 months and those surviving over 18 months. In cases of tumors occluding the first- or second-order portal branches or occupying more than 20% of the liver, or relatively hypovascular tumors with unclear boundaries, survival was not different between TAE- and non-TAE-treated patients, whereas it was significantly improved by TAE in cases without these findings. These results suggest that TAE is beneficial in cases of unresectable HCC complicating liver cirrhosis, but its benefit is limited under certain conditions.

Adult↗
PubMed1985

The acute effects of prostaglandin E1 on the pulmonary circulation and oxygen delivery in patients with the adult respiratory distress syndrome.

Prostaglandin E1 was administered intravenously to 10 patients who had the adult respiratory distress syndrome associated with severe infection in order to investigate its hemodynamic effects. Infusion of PGE1 significantly decreased the mean pulmonary arterial pressure, mean systemic arterial pressure, pulmonary vascular resistance and systemic vascular resistance, and increased the cardiac index, oxygen delivery and oxygen consumption. No significant difference was noted in the intrapulmonary shunt fraction. These results indicate that administration of PGE1 improves pulmonary hemodynamics and tissue oxygenation in patients with acute respiratory distress syndrome, by reducing right ventricular afterload and increasing the cardiac index.

Aged↗
PubMed1985

Chromosomal localization of the Epstein-Barr virus (EBV) genome in Bloom's syndrome B-lymphoblastoid cell lines transformed with EBV.

The localization of the Epstein-Barr virus (EBV) genome in chromosomes of human B-lymphoblastoid cell lines (LCLs) transformed with EBV, and the effect of EBV DNA on the level of sister chromatid exchange (SCE) in Bloom's syndrome (BS) B-LCLs, were examined with chromosomal in situ hybridization techniques using a 3H-EBV DNA probe. EBV DNA was detected in chromosomes 1-5 and 13-15 at specific G band regions in BS as well as in normal B-LCLs, regardless of SCE. Several chromosomal sites (1p31, 1q31, 4q22-24, 5q21, 13q21, 14q21) carrying EBV DNA seemed to be very characteristic in normal as well as in BS B-LCLs. There was no statistically significant difference in silver grain counts due to EBV DNA and their distribution in different chromosomes or groups among normal and BS B-LCLs with normal and high SCE. These findings strongly indicate that EBV infection did not introduce a correcting factor for BS SCE.

B-Lymphocytes↗
PubMed1985

Benefit of transcatheter arterial embolization for ruptured hepatocellular carcinoma complicating liver cirrhosis.

In 6 patients with spontaneous rupture of hepatocellular carcinoma complicating liver cirrhosis, but with no occlusion of the main portal trunk, transcatheter arterial embolization was performed within 7 days of the rupture. All 6 patients were thought to be inoperable because of shock state or severe hepatic dysfunction. In all 6 patients, the progressive decrease in the hematocrit ceased soon after the embolization. Five patients survived for 31-168 days after the embolization; 1 patient who developed septicemia died 10 days later. We conclude that transcatheter arterial embolization is beneficial as a procedure of first choice for ruptured hepatocellular carcinoma when the portal blood flow is maintained.

Adult↗
PubMed1985

Thymosin alpha 1 exerts protective effect against the 5-FU induced bone marrow toxicity.

Thymosin alpha 1 was shown to prevent the 5-fluorouracil(5-FU)-induced bone marrow toxicity in BDF1 mice, as determined by the cellularity, haemopoietic stem cells (CFU-s) and granulocyte-macrophage colony forming unit (GM-CFU). Furthermore, thymosin alpha 1 increased the levels of colony stimulating factor (CSF) in sera or in culture media of spleen cells derived from 5-FU-treated mice. The treatment of spleen cells with anti-Thy 1,2 antibody plus complement abolished completely the CSF production. The in vivo treatment of donor mice with anti-Thy 1,2 antibody following 5-FU abolished completely the capability of their bone marrow cells to save lethally irradiated recipients. Thymosin alpha 1 treatment prevented the damage by such combined treatment. The present study indicates that thymosin alpha 1 exerts its protective effect against the 5-FU-induced bone marrow toxicity, at least partially, through its effect on the maturation of immature T cells to functional T cells which produce various kinds of lymphokines including CSF.

Animals↗
PubMed1985

Rabbit liver alcohol dehydrogenase: purification and properties.

Alcohol dehydrogenase [EC 1.1.1.1] was purified to homogeneity from rabbit liver by water extraction, DEAE-cellulose treatment, affinity chromatography on 5'-AMP-Sepharose and gel filtration on Sephadex G-150 using dithiothreitol as a stabilizer. The purified enzyme has an estimated molecular weight of 72,000 and consists of two subunits with a molecular weight of about 36,000 each. The enzyme contains 4 g-atoms of zinc and 18 sulfhydryl groups per mol of protein and exhibits maximal activity at pH 10.8, with a second maximum at pH 7.5. The apparent Km values for ethanol and NAD+ are 0.45 mM and 53.19 microM, respectively, at pH 10.8 and 3.33 mM and 6.94 microM, respectively, at pH 7.5. The enzyme oxidizes ethanol most readily among the aliphatic alcohols studied and has very low substrate specificity for methanol. Among steroid alcohols, 5 beta-androstan-3 beta-ol-17-one serves as a substrate for the enzyme. Pyrazole and 4-methylpyrazole (which are well known alcohol dehydrogenase inhibitors), sulfhydryl reagents, heavy metal ions and metal-chelating agents inactivate the enzyme.

Alcohol Dehydrogenase↗
PubMed1985

Ferredoxin from a liverwort, Marchantia polymorpha. Purification and amino acid sequence.

Marchantia polymorpha ferredoxin was purified by DE-52 and Sephadex G-75 column chromatographies to homogeneity. The complete amino acid sequence of the carboxymethylated (Cm) ferredoxin was determined by conventional methods to be as follows. Thr-Phe-Lys- Val-Thr-Leu-Asn-Thr-Pro-Thr-Gly-Gln-Ser-Val-Ile-Asp-Val-Glu-Asp- Asp-Glu-Tyr-Ile-Leu-Asp-Ala-Ala-Glu-Glu-Ala-Gly-Leu-Ser-Leu-Pro- Tyr-Ser-Cys-Arg-Ala-Gly-Ala-Cys-Ser-Ser-Cys-Ala-Gly-Lys-Val-Thr- Ala-Gly-Glu-Val-Asp-Gln-Ser-Asp-Glu-Ser-Phe-Leu-Asp-Asp-Asp-Gln- Met-Asp-Glu-Gly-Tyr-Val-Leu-Thr-Cys-Ile-Ala-Tyr-Pro-Thr-Ser-Asp- Leu-Thr-Ile-Asp-Thr-His-Gln-Glu-Glu-Ala-Leu-Ile. The total number of amino acid residues was 95 and the molecular weight was calculated to be 10,174, excluding iron and sulfur atoms. The distribution of the four cysteine residues chelating the two iron atoms was identical to those of other [2Fe-2S] ferredoxins. The relationship between M. polymorpha and other plants was discussed in terms of plant phylogeny.

Amino Acid Sequence↗
PubMed1985

Intracellular Localization of Lunularic Acid and Prelunularic Acid in Suspension Cultured Cells of Marchantia polymorpha.

Intracellular localization of lunularic acid and prelunularic acid in suspension cultured cells of Marchantia polymorpha L. was studied. The sum of both compounds was determined as lunularic acid group (LNAs) because of the instability of prelunularic acid to convert into lunularic acid.Mechanical disruption of the cells followed by differential centrifugation showed that LNAs was associated with the supernatant of 100,000g centrifugation. Protoplasts isolated from the cells were osmotically ruptured and the distribution of LNAs among the organelles was examined by discontinuous density gradient centrifugation of the protoplast contents. Successful isolation of intact chloroplasts, mitochondria and peroxisomes free from cytoplasm indicated that LNAs was not accumulated in these organelles. Flotation techniques resulted in an efficient isolation of pure vacuoles and revealed that LNAs was distributed almost equally in the vacuoles and cytoplasm.

Journal Article↗
PubMed1985

Histamine is an antagonist of the acetylcholine receptor at the frog endplate.

The effects of histamine on the acetylcholine (ACh) receptor-channel complex were examined by means of voltage-clamp at the frog endplate. ACh was ionophoretically applied to the endplate. Histamine was added to the perfusate. Histamine (100 nM - 1 mM) reversibly depressed the peak amplitude of the ACh-induced inward current in a dose-dependent manner. The double reciprocal plot of the dose-response relationship between the peak ACh current and the amount of ACh applied suggested that histamine (100 microM) depressed the ACh-induced current in a competitive manner. Histamine prevented the specific ACh binding site within the receptor-channel complex from binding erabutoxin, a sea-snake venom, which binds irreversibly to the specific ACh binding site. Histamine had no detectable effects on the equilibrium potential of the endplate current but shortened the half-decay time of the endplate current in a voltage-dependent manner. It was therefore concluded that histamine blocks not only the specific ACh binding site but also interacts with the ACh-channel site. The present experiments strongly suggest that histamine can act as an antagonist to modulate nicotinic cholinergic transmission.

Acetylcholine↗
PubMed1985

[Studies on the occupational maladjustment syndrome (Part 2). In reference to relationship between psychophysiological characters and clinical features].

In a previous report (Natsume et al., Jpn. J. Ind. Health, Vol. 24) on the occupational maladjustment syndrome (O.M.A.S.), on the basis of clinical data, we classified patients with O.M.A.S. into 5 subcategories; core, drop-out, transient reaction, special job maladjustment and other. The core and drop-out types are typical of O.M.A.S. In order to test our hypothesis regarding the clinical and psychophysiological character of patients with O.M.A.S., 39 subjects (25 core type and 14 drop-out type) were studied by polygraphic techniques such as EEG, EMG of facial muscles and electrooculogram, and the results were compared with those of 16 normal subjects. We were specifically interested in their behavior in mental arithmetic and at rest. The results are summarized as follows: At rest, less frequent irregular rapid eye movement (especially "r-type") and smaller amplitudes of the corrugator supercilii muscle characterized the patients compared to the normals. During mental arithmetic these two indicators showed a greater tendency to increase in the core type than in the normals, but they remained unchanged in the drop-out group. In the core type subjects, the increased levels in these indicators persisted briefly after the arithmetic sessions. We discuss the relationship between the clinical character of the two types and the above results. We consider that the psychophysiological character of the two types may play an important role in the pathogenetic mechanism of O.M.A.S.

Adjustment Disorders↗
PubMed1985

[Study of somatosensory evoked response (SER) in patients with occupational vibration disease. Effect on SER induced by load of hot and cold water, and depressing the brachium].

Somatosensory evoked responses (SERs) to mechanical stimulation were recorded in 5 patients with occupational vibration disease and 10 grader drivers, and the results were compared with those obtained from 48 normal subjects. SERs were recorded at room temperature of 20-23 degrees C and after immersing the hand in hot (40 degrees C) or cold (10 degrees C) water for 5 minutes. SERs were also recorded while depressing the brachium and soon thereafter to examine the effect of ischemia. The following results were obtained. In SERs recorded on the finger of patients with occupational vibration disease, it was observed that some peaks of SERs were absent in 6 out of the 10 cases and that peak latency time was abnormally prolonged in 3 out of them. On the other hand, in SERs recorded on the forearm, abnormality was observed in only 1 out of them. In recording SERs in 6 patients with occupational vibration disease after immersing the hands in hot water, it was observed that abnormal SERs became normal in all 6 cases. However, these normalized SERs became abnormal in 5 out of the 6 cases within 25 minutes after removing the hands from hot water. No appreciable change could be observed in SERs recorded after immersing the hands in cold water. Partial absence of SER peaks could be observed in 2 out of 9 grader drivers while depressing the brachium. On the other hand, all SERs in 7 normal cases did not show any abnormality while depressing the brachium. The results suggest the presence of a close relationship between peripheral vascular dysfunction and peripheral somatosensory disturbance in patients with occupational vibration disease. However, it was observed that peripheral vascular dysfunction could not always trigger peripheral neural dysfunction. These findings have led to the conclusion that SERs to mechanical stimulation are more useful in the diagnosis of dysfunction of the peripheral nerve in patients with occupational vibration disease than SERs to electrical stimulation. The findings suggest that immersion in hot water and cold water and depression of the brachium are useful sensory tests for patients with occupational vibration disease and grader drivers.

Adult↗