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Biomedical subjects

H Oishi

Publications and source records attributed to H Oishi.

At least 37 records · Page 2Linked to original sources
PubMed1999

[A case of subarachnoid hemorrhage verified as cerebral vasospasm by using three-dimensional CT angiography (3 D-CTA): reference to comparison with conventional angiography].

The authors present a case of aneurysmal subarachnoid hemorrhage that were verified as cerebral vasospasm by using both three-dimensional CT angioraphy (3 D-CTA) and conventional angiography. A 45-year-old man was referred to our department 4th day after sudden onset of a severe headache. On admission, emergency 3 D-CTA showed the cerebral vasospasm involving M 1 segment. Conventional angiography performed at the same day of the left internal carotid artery confirmed the cerebral vasospasm of the same vessel as 3 D-CTA, and furthermore demonstrated the left middle cerebral artery (MCA) and anterior cerebral artery (ACA) genu aneurysms. The former was seen as a ruptured aneurysm from brain CT findings (Fisher group 3). On the 10th day after the onset, 3 D-CTA demonstrated the remaining severe cerebral vasospasm of the supraclinoid portion of left ICA and M 1 segment. Findings at the conventional angiography subsequently performed were concordant with those of 3 D-CTA. The patient was successfully treated with delayed surgical clipping for both aneurysms without the symptoms related to the cerebral vasospasm and discharged without neurological abnormality. We consider that 3 D-CTA shows promise as a minimally invasive method of evaluating the cerebral vasospasm and would take the place of the conventional angiography.

Cerebral Angiography↗
PubMed1998

Localization of the Rab3 small G protein regulators in nerve terminals and their involvement in Ca2+-dependent exocytosis.

The Rab3 small G protein subfamily (Rab3) consists of four members, Rab3A, -B, -C, and -D. We have recently isolated and characterized the Rab3 regulators, GDP/GTP exchange protein (GEP) and GTPase activating protein (GAP), both of which are specific for the Rab3 subfamily. Rab3 GEP stimulates the conversion of the GDP-bound inactive form to the GTP-bound active form, whereas Rab3 GAP stimulates the reverse reaction. Of the four members of the Rab3 subfamily, evidence is accumulating that Rab3A is involved in Ca2+-dependent exocytosis, particularly in neurotransmitter release. We first analyzed the subcellular localization of Rab3 GEP and GAP in rat brain. Subcellular fractionation analysis showed that both Rab3 GEP and GAP were enriched in the synaptic soluble fraction. Immunocytochemical analysis in primary cultured rat hippocampal neurons showed that both Rab3 GEP and GAP were concentrated at the presynaptic nerve terminals. We then examined whether Rab3 GEP and GAP were involved in Ca2+-dependent exocytosis by use of human growth hormone (GH) co-expression assay system of cultured PC12 cells. Overexpression of the deletion mutant of Rab3 GEP possessing the catalytic activity reduced the high K+-induced GH release without affecting the basal GH release, whereas that of the deletion mutant lacking the catalytic activity showed no effect on the high K+-induced GH release. In contrast, overexpression of Rab3 GAP or its deletion mutant possessing the catalytic activity did not affect the high K+-induced GH release or the basal GH release. These results indicate that Rab3 GEP and GAP are colocalized with Rab3A at the synaptic release sites and suggest that they regulate the activity of Rab3A and are involved in Ca2+-dependent exocytosis.

Animals↗
PubMed1998

Rho and Rab small G proteins coordinately reorganize stress fibers and focal adhesions in MDCK cells.

The Rho subfamily of the Rho small G protein family (Rho) regulates formation of stress fibers and focal adhesions in many types of cultured cells. In moving cells, dynamic and coordinate disassembly and reassembly of stress fibers and focal adhesions are observed, but the precise mechanisms in the regulation of these processes are poorly understood. We previously showed that 12-O-tetradecanoylphorbol-13-acetate (TPA) first induced disassembly of stress fibers and focal adhesions followed by their reassembly in MDCK cells. The reassembled stress fibers showed radial-like morphology that was apparently different from the original. We analyzed here the mechanisms of these TPA-induced processes. Rho inactivation and activation were necessary for the TPA-induced disassembly and reassembly, respectively, of stress fibers and focal adhesions. Both inactivation and activation of the Rac subfamily of the Rho family (Rac) inhibited the TPA-induced reassembly of stress fibers and focal adhesions but not their TPA-induced disassembly. Moreover, microinjection or transient expression of Rab GDI, a regulator of all the Rab small G protein family members, inhibited the TPA-induced reassembly of stress fibers and focal adhesions but not their TPA-induced disassembly, indicating that, furthermore, activation of some Rab family members is necessary for their TPA-induced reassembly. Of the Rab family members, at least Rab5 activation was necessary for the TPA-induced reassembly of stress fibers and focal adhesions. The TPA-induced, small G protein-mediated reorganization of stress fibers and focal adhesions was closely related to the TPA-induced cell motility. These results indicate that the Rho and Rab family members coordinately regulate the TPA-induced reorganization of stress fibers and focal adhesions that may cause cell motility.

Actins↗
PubMed1998

Phospholipid deacylating activities included in yeast.

Yeast had been known to contain only one kind of phospholipid deacylating enzyme with an optimal pH in the acidic range. However, among 8 genera and 25 strains, 7 genera and 13 strains had phospholipid deacylating activity at pH 8.0, when screening of enzyme activity was done with micellar and liposomal substrates. The enzymatic properties of phospholipid deacylating enzyme existing in yeast was not related to genetic identity based on 18S rRNA gene sequence. The results suggest that yeast contains enzymes showing a variety of properties depending on the species of yeast, and further studies on this enzyme with more varieties of yeasts are necessary for understanding the physiological roles of the enzyme in yeast.

Fatty Acids, Nonesterified↗
PubMed1998

Histological analysis of the aortic nerve in the rat raised in space (Rapid communication on Neurolab Project).

To study development of the aortic nerve baroreflex under conditions of microgravity, we examined the cross section of the left aortic nerve (LAN), which is the afferent of the baroreflex, in the neonate rats aged 25 days raised in microgravity on the space shuttle Columbia (flight:FLT group) for 16 days. In this paper, we report a part of the result obtained from the data of the myelinated fibers of LAN analyzed with an electron microscope. Two kind of ground control groups were compared to the FLT group; one was asynchronous ground control (AGC) group where the rats were housed in the same cage as that on the shuttle, and the other was vivarium(VIV) group where the rats were housed in a commercial cage. The LANs in each group were extirpated the from rats perfused with a fixative and embedded for histological analysis. We observed the transverse sections of LAN and took pictures of several areas (magnified to x 2K to x 200K). No irregular myelination was found in all fibers of FLT group when they were compared with two control groups. The thickness of myelin of the maximally myelinated fibers were 0.55 +/- 0.17 micrometer in FLT(n=5), 0.45 +/- 0.10 micrometer in AGC(n=5), and O.47 +/- 0.06 micrometer meter in VIV(n=5). There was no significant difference among three groups (unpared t-test). The results suggest that there is no effect of space environment on the myelin formation of each nerve fiber in the aortic nerve.

Animals↗
PubMed1998

[Treatment of hepatocellular carcinoma by segmental SMANCS Lipiodol-TAE].

Segmental SMANCS Lipiodol TAE (Seg. SMANCS Lp-TAE) using SMANCS was used to treat HCC in 58 patients and was evaluated in comparison with Seg. Lp-TAE using Epirubicin performed in 50 patients with respect to the course of atrophy of the embolized area, recurrence rate and side effects. On serial CT (Lp-CT) performed after TAE, in cases with P type in which the tumor is present in the periphery of the embolized area and showing Type I homogeneous accumulation of Lp within the tumor, the incidence of atrophy in the embolized area including the tumor was high and the recurrence rate was low. Although no significant difference in the recurrence rate was noted between the groups in which SMANCS and EPI were used, there were more cases with marked atrophy and a lower recurrence rate in the former. No difference was found in post-procedural side effects such as fever between the two groups, while hypotension was rarely observed during the procedure in the group in which SMANCS was used and was easily managed with intravenous steroids. The present results suggest that Seg. SMANCS Lp-TAE is an effective local treatment for HCC limited to a subsegment or segment.

Aged↗
PubMed1998

[Application of percutaneous trans esophageal gastro-tubing (PTEG) in to home care for a patient with terminal stage of gastric cancer].

PURPOSE: Since 1994, we devised and have continued to develop a percutaneous trans esophageal gastro-tubing (PTEG) as an effective technique to drain gastrointestinal contents of critical patients suffering from gastric carcinoma. Here we report our satisfactory experience with a critical gastric cancer patient for whom we improved QOL by the application of the PTEG technique. The patient suffered from severe stenosis or obstruction of the digestive tract. This method was found to be effective enough to enable the patient to receive further medical care at home. CASE: The patient was a 36-year-old female who had far-advanced, inoperable gastric carcinoma. It was therefore decided to use the PTEG method. METHOD: The PTEG method was performed using a rupture-free balloon (RFB) catheter to drain the gastrointestinal contents. A reservoir-port for IVH use was embedded to control the patient's nutrition. A morphine hydrochloride suppository was then given for the pain. REMARK: PTEG was found to be effective, safe and simple; moreover, it is a less-invasive, intestine-maintaining method, which enabled the patient to continue receiving further medical treatment at home.

Adult↗
PubMed1997

Relationship between plasma concentrations of beta-carotene and alpha-tocopherol and life-style factors and levels of DNA adducts in lymphocytes.

beta-Carotene and alpha-tocopherol have been thought to reduce risk of lung cancer. Whether beta-carotene and alpha-tocopherol influence human DNA adducts, indicators of biologically effective doses of carcinogens, has been seldom studied. In this cross-sectional study, we measured plasma beta-carotene and alpha-tocopherol in 192 healthy men and DNA adducts in lymphocytes in 104 of the subjects. Because genetic polymorphism of cytochrome P-4501A1 (CYP1A1) and glutathione S-transferase M1 (GSTM1) has been associated with interference in formation of reactive intermediates and detoxification of polycyclic aromatic hydrocarbons, we also obtained data concerning genetic polymorphism of CYP1A1 and GSTM1. In multiple regression analysis, parameters such as alcohol consumed per day, high-density lipoprotein cholesterol, Quetelet index, and cigarettes smoked per day were correlated inversely, whereas age, plasma alpha-tocopherol, and intake frequency of fruits were correlated positively with plasma beta-carotene concentration. DNA adduct levels of high plasma beta-carotene or alpha-tocopherol groups were not significantly different from the DNA adduct levels of low plasma beta-carotene or alpha-tocopherol groups among current smokers or nonsmokers. In variant states of CYP1A1 or GSTM1 polymorphism, after controlling for effect of cigarettes smoked per day, no significant correlation was found between plasma beta-carotene or alpha-tocopherol and DNA adduct levels. These results indicated that alcohol consumption, cigarette smoking, and plasma alpha-tocopherol have a close relationship with plasma beta-carotene. The plasma beta-carotene and alpha-tocopherol were not likely to influence the level of DNA adducts in lymphocytes.

Adolescent↗
PubMed1997

Antibodies to hepatitis C virus and elevated transaminase levels in a town of hyperendemicity in Iwate, Japan.

In an annual survey for liver function tests in persons aged > 35 years in Iwate Prefecture, Japan, a town was identified where high levels of alanine aminotransferase abounded. Of 5152 inhabitants aged > 35 years in this town, antibodies to hepatitis C virus (HCV) determined by enzyme-linked immunosorbent assay with HCV core peptides were detected in 798 (15.5%) people, hepatitis B surface antigen was detected in 47 (0.9%) people and antibodies to hepatitis B surface antigen and/or hepatitis B core antigen unaccompanied by surface antigenaemia were detected in 1748 (33.9%) people. Antibodies to HCV core peptides correlated closely with the antibodies detected by passive haemagglutination with recombinant HCV proteins of the second generation. Antibodies to HCV core peptides were particularly common in one of the nine districts of the town (district 8), where 276 (45.3%) of 609 inhabitants tested positive; there were no differences in the frequency of serological markers of hepatitis B virus (HBV) infection among residents in the nine districts. Of the 798 individuals with antibodies to HCV core peptides, 257 (32.2%) were found to have elevated transaminase levels. A history of transfusion was associated with a high frequency of antibodies to HCV core peptides, except in district 8 where such antibodies were equally frequent in residents irrespective of transfusions. These results indicate an epidemiology of HCV distinct from that of HBV in this town and a very local spread of HCV, as well as a high frequency of hepatic injuries in individuals with antibodies to HCV.

Adult↗
PubMed1996

Disruption of phospholipase B gene, PLB1, increases the survival of baker's yeast Torulaspora delbrueckii.

An uracil auxotrophic mutant of baker's yeast Torulaspora delbrueckii, which is resistant to 5-fluoro-orotic acid, was complemented by transformation with YEp24 which harbors 2 microns origin and URA3 derived from Saccharomyces cerevisiae. The phospholipase B in T. delbrueckii cells is active in both acidic and alkaline conditions. However, activity of phospholipase B gene (PLB1) in cells of disruption mutant (plb1:: URA3) was lost in both conditions, which indicates that all phospholipase B activity is encoded by a single gene (or a single polypeptide) in these yeast cells. Over-expression of PLB1 with YEp plasmid vector in T. delbrueckii cells showed approximately 2.5-fold increase in phospholipase B activity, comparing with that in wild-type cells. Cells of plb1 delta mutant showed increased survival when cells of plb1 delta mutant and wild-type strain were incubated in water at 30 degrees C. Cells of PLB1-over-expressed strain died rapidly even during the cultivation period, indicating that phospholipase B activity may be a determinant for the survival of this yeast.

Bread↗
PubMed1996

Interaction of both the C2A and C2B domains of rabphilin3 with Ca2+ and phospholipid.

Rabphilin3, a downstream target molecule of the Rab3 subfamily small G proteins, has two C2 domains (the C2A and C2B domains) at its C-terminal region and is implicated in Ca(2+)-dependent neurotransmitter release. Rabphilin3 interacts with Ca2+ and phospholipid at its C2 domain, but it remains to be clarified which domain, the C2A or C2B domain, interacts with these compounds. We have found here that both the C2A and C2B domains interact with Ca2+ with similar kinetics but interact with phospholipid with slightly different kinetics.

Adaptor Proteins, Signal Transducing↗
PubMed1996

Comparison between males and females with respect to the porphyrin metabolic disorders found in workers occupationally exposed to lead.

To elucidate the sex difference in porphyrin metabolic disorders induced by lead exposure, we determined plasma delta-aminolevulinic acid (ALA), urinary ALA, and urinary coproporphyrin (CP) in 298 lead-exposed workers (160 males and 138 females), and compared the data thus obtained. The use of fluorometric high-performance liquid chromatography (HPLC) method which is highly sensitive and specific made possible the measurement of ALA in a small volume (50 microliters) of plasma. The concentrations (mean +/- SD) of lead in blood (males: 55.1 +/- 12.9 micrograms/dl; females: 54.7 +/- 13.5 micrograms/dl) indicated that the intensity of occupational exposure to lead was almost equal in the two groups. However, the elevation of plasma ALA concentration and the increased urine ALA and CP excretion among these lead workers were much higher in females than in males, confirming the finding of a sex difference in the biological effect of human exposure. The difference in urine CP excretion was especially pronounced, the mean concentration of urinary CP in the female workers being 3.5-5 times higher than that in the male workers.

Adult↗
PubMed1996

Chronic lead exposure may inhibit endothelium-dependent hyperpolarizing factor in rats.

We designed experiments to determine the effect of chronic lead exposure on endothelium-dependent responses to acetylcholine (Ach) in rat isolated blood vessels. Male Wistar rats were maintained for 1 or 3 months with or without oral lead administration. Membrane potential and isometric tension were measured in mesenteric arteries. Ach caused concentration- and endothelium-dependent relaxation in rings with endothelium contracted with phenylephrine (PE). There was no significant difference in relaxation between lead-exposed and control animals. In the presence of NG-nitro-L-arginine methyl ester (L-NAME), both endothelium-dependent hyperpolarization and relaxation to Ach were significantly reduced in animals from the 3-month lead-exposed group. In aorta from lead-exposed groups, endothelium-dependent relaxation to Ach was not significantly different from that of age-matched controls, whereas both were completely inhibited in the presence of L-NAME. The basal levels of cyclic GMP in the aorta were not affected by lead exposure regardless of duration. These data indicate that both endothelium-dependent hyperpolarization and L-NAME-resistant relaxation decrease with chronic lead exposure in rat mesenteric arteries and suggest that lead is an inhibitor or endothelium-derived hyperpolarizing factor (EDHF).

Acetylcholine↗
PubMed1996

Purification and some properties of phospholipase B from Schizosaccharomyces pombe.

Phospholipase B from Schizosaccharomyces pombe was purified by ammonium sulfate fractionation and chromatographed on phenyl-Sepharose CL-4B, DEAE-Toyopearl 650M, and TSK gel G4000SW columns. The purified enzyme was a glycoprotein with molecular weight of approximately 300,000 and 100,000-150,000 by gel filtration and SDS-polyacrylamide gel electrophoresis, respectively. The isoelectric point was pH 4.7. The optimum pH of the enzyme was 2.5 and no activity was detected at neutral and alkaline pHs. The enzyme was not heat-stable. Enzyme activity was slightly stimulated by divalent ions except Fe2+ and 0.1% sodium deoxycholate, and inhibited by Fe2+, Fe3+, 0.1% sodium dodecyl sulfate, and 0.01% cetyltrimethylammonium bromide. The enzyme hydrolyzed mono- and diacylphospholipids, and phosphatidylinositol was hydrolyzed most preferentially. Triglyceride was not hydrolyzed. The enzyme also had acyltransferase activity on lysophosphatidylcholine, forming the corresponding diacylphosphatidylcholine.

Acyltransferases↗