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Biomedical subjects

Y Shinohara

Publications and source records attributed to Y Shinohara.

At least 91 records · Page 5Linked to original sources
PubMed1999

Expression of inducible nitric oxide synthase immunoreactivity in rat brain following chronic hypoxia: effect of aminoguanidine.

To clarify the role of inducible nitric oxide synthase (iNOS) in the histopathological changes that occur in the brain after exposure of rats to normobaric hypoxia (10% O2 in N2) for 2 weeks, we examined the localization of iNOS and the effect of aminoguanidine, a relatively selective iNOS inhibitor, on the histological outcome. Animals were divided into a hypoxia group, an aminoguanidine-treated hypoxia group and a normoxic control group. The hypoxia group showed severe ischemic changes and prominent angiogenesis in the CA1 hippocampus and cerebral cortex. Aminoguanidine significantly reduced the ischemic change and angiogenesis in these regions, and also reduced iNOS-immunoreactive cells compared to the hypoxia group. These findings suggest that iNOS activity could play a role in the neuropathological alterations induced by chronic hypoxia.

Animals↗
PubMed1999

Multiple cerebral infarctions associated with ovarian hyperstimulation syndrome.

A 26-year-old woman on human menopausal gonadotrophin-human chorionic gonadotrophin therapy for sterility showed multiple cerebral infarctions associated with ovarian hyperstimulation syndrome. A hypercoagulable state (hemoconcentration, increased plasma levels of D-dimer and thrombin-antithrombin III complex, and decreased protein S activity) was associated with her thromboembolic events. Cerebral infarction associated with mild neurologic deficits may be overlooked in patients with ovarian hyperstimulation syndrome.

Adult↗
PubMed1999

7-Nitroindazole attenuates nitrotyrosine formation in the early phase of cerebral ischemia-reperfusion in mice.

The purpose of this study was to evaluate the role of neuronal nitric oxide synthase (nNOS) in nitrotyrosine (NO2-Tyr) formation in the early phase of ischemia-reperfusion in mouse brain. Using a hydrolysis/high pressure liquid chromatography (HPLC) procedure (0.6 microM detection limit), we measured %NO2-Tyr (ratio of NO2-Tyr to total tyrosine) in 23 male C57Black/6J mice subjected to 2-h middle cerebral artery occlusion followed by 0.5-h reperfusion, in the presence (25 or 50 mg/kg) and absence of 7-nitroindazole (7-NI), a relatively specific nNOS inhibitor. At 25 mg/kg, 7-NI reduced NO2-Tyr formation to about a half of that in the vehicle-treated group (0.10 +/- 0.07 vs. 0.18 +/- 0.05%), while 50 mg/kg suppressed NO2-Tyr formation to below the limit of detection, indicating that nNOS is responsible for most of the NO2-Tyr formation in the early phase after reperfusion.

Animals↗
PubMed1999

Fluctuation of the first loop facing the matrix of the mitochondrial ADP/ATP carrier deduced from intermolecular cross-linking of Cys56 residues by bifunctional dimaleimides.

The effects of six thiol-specific cross-linker dimaleimides, in which the distance of the two maleimide groups ranged from 7.7 to 16. 8 A, on bovine heart mitochondria were studied at pH 7.2 and 0 degrees C. None of the dimaleimides affected mitochondrial proteins, but they caused significantly specific intermolecular cross-linking of the 30 kDa ADP/ATP carrier in submitochondrial particles. All the cross-links were found to be formed specifically between two Cys56 residues in the first loop facing the matrix, as we observed previously in intermolecular disulfide bridge formation catalyzed by copper o-phenanthroline [Majima, E., Ikawa, K., Takeda, M., Hashimoto, M., Shinohara, Y., and Terada, H. (1995) J.Biol. Chem. 270, 29548-29554]. The dimerization was dependent on the cross-linking span of the dimaleimides, being maximum with the dimaleimide having a span of about 12 A. Cross-linking took place in the m-state carrier, but not in the c-state carrier, and inhibited ADP transport via the ADP/ATP carrier. We suggest that a pair of first loops with Cys56 residues in the dimer form of the m-state carrier fluctuates widely with a most probable distance between them of about 12 A, and that this fluctuation modulates the transport activity of the ADP/ATP carrier.

Adenosine Diphosphate↗
PubMed1999

Expression of the bovine heart mitochondrial ADP/ATP carrier in yeast mitochondria: significantly enhanced expression by replacement of the N-terminal region of the bovine carrier by the corresponding regions of the yeast carriers.

To characterize the transport mechanism mediated by the mammalian mitochondrial ADP/ATP carrier (AAC), we tried to express bovine heart mitochondrial AAC (bhAAC) in Saccharomyces cerevisiae. The open reading frame of the bhAAC was introduced into the haploid strain WB-12, in which intrinsic AAC genes were disrupted. Growth of the transformant was very low in glycerol medium, and a little amount of bhAAC was detected in the mitochondrial membrane. For improvement of bhAAC expression in WB-12, we introduced DNA fragments encoding chimeric bhAACs, in which the N-terminal region of the bhAAC extending into the cytosol was replaced by the corresponding regions of the type 1 and type 2 yeast AAC isoforms (yAAC1 and yAAC2). These transformants grew well, and the amounts of the chimeric bhAACs in their mitochondria were as high as that of yAAC2. The carriers expressed showed essentially the same ADP transport activities as that of AAC in bovine heart mitochondria.

Amino Acid Sequence↗
PubMed1999

Induction and enhancement of stress proteins in a trichloroethylene-degrading methanotrophic bacterium, Methylocystis sp. M.

The responses of the trichloroethylene-degrading bacterium Methylocystis sp. M to six different water-pollutants, carbon starvation, and temperature-shock (heat and cold) were examined using 2-dimensional gel electrophoresis. Twenty-eight polypeptides were induced, and these stress-induced proteins were classified into three groups. Some of the chemically induced proteins were the same as those induced by carbon starvation and temperature-shock. Two of the polypeptides were induced by trichloroethylene. Trichloroethylene-stress protein synthesis required 1-2 h at a concentration of trichloroethylene that had no effect on growth. Furthermore, 25 stress-enhanced polypeptides were observed, and one of these was enhanced by trichloroethylene. Based on these results, we discuss applications of chemical-stress induction of proteins to establish effective bioremediation and bioassay by methanotrophs.

Bacteria↗
PubMed1999

Recurrent hepatocellular carcinoma successfully treated with radiofrequency thermal ablation.

We report a patient with hepatocellular carcinoma (HCC) who was successfully treated with radiofrequency thermal ablation (RFA). A 71-year-old man was admitted to our hospital in August 1996 with recurrence of HCC. Partial hepatic resection had been performed in January 1993 for HCC that had measured 1.3 cm in segment VIII, and subsequently he had received six sessions of percutaneous ethanol injection (PEI) for treatment of recurrence. Dynamic computed tomography (CT) performed in August 1996 showed two recurrent tumors, one measuring 3.8 cm in segment VIII adjacent to the right hepatic vein, and one measuring 2.0 cm in segment V. Three sessions of percutaneous RFA were performed. After this treatment, most of the tumor in segment VIII and all the tumor in segment V showed low density on dynamic CT, and the right hepatic vein was preserved. However, a remnant of the mass appeared near the right hepatic vein 2 months after the treatment. An additional two sessions of RFA were performed. After the end of treatment, serum alpha-fetoprotein level dropped to the normal range, and no sign of recurrence has been observed until September 1998.

Aged↗
PubMed1999

Lectin-carbohydrate interactions: fine specificity difference between two mannose-binding proteins.

Two types of rat mannose-binding proteins (MBPs), MBP-A (serum type) and MBP-C (liver type), have similar binding specificity for monosaccharide and similar binding site construct according to the X-ray structure, but exhibit different affinity toward natural oligosaccharides and glycoproteins. To understand the basis for this phenomenon, we used cloned fragment of MBP-A and -C (entire carbohydrate-recognition domain and a short connecting piece) that exists as stable trimers in various binding studies. Binding of a number of mannose-containing di- and tri-saccharides and high-mannose type oligosaccharides indicated that MBP-C has an extended binding area of weak interaction with the second and the third mannose residues, whereas MBP-A recognizes just a single mannose residue. In addition, MBP-C has a weak secondary binding site some 25 A away from the primary site. These findings explain the higher affinity of MBP-C for natural high-mannose type oligosaccharides as compared to MBP-A. A huge affinity differential manifested by natural glycoproteins (e.g., inhibitory potency of thyroglobulin is approximately 200 fold higher for MBP-C than for MBP-A in a solid-phase assay) may be due to steric hindrance experienced by MBP-A in the competition assay, and suggests different arrangement of subunit in the MBP trimers.

Animals↗
PubMed1999

K-ras codon 12 and p53 mutations in biopsy specimens and bile from biliary tract cancers.

To evaluate whether it is useful for diagnosis to detect K-ras and p53 mutations in biopsy specimens and bile of biliary tract lesions, 12 cholangiocarcinomas (CC), eight cases of cholangitis, seven gallbladder carcinomas (GBC), seven gallbladder cholesterol polyps, four cases of adenomyomatosis of the gallbladder and five cases of cholecystitis were examined. K-ras and p53 mutations in bile were detected by a two-step polymerase chain reaction (PCR) and nested PCR-single-strand conformation polymorphism (SSCP) analysis. In addition, p53 protein expression in biopsy specimens from CC were examined by immunostaining. K-ras mutations at codon 12 were detected in 50% of CC and 57.1% of GBC in both biopsy specimens and bile. The incidence of p53 mutations was 33.3% in CC and 42.9% in GBC. p53 protein overexpression was observed in 60% CC biopsy specimens. In contrast, K-ras and p53 abnormalities were not detected in any non-neoplastic biliary tract lesion. K-ras and p53 mutations in biliary tract cancers showed the same mutation patterns in spite of differences in the collection methods used between bile and biopsy specimens or surgically resected tissue. Genetic analysis of K-ras and p53 mutations in biopsy specimens and bile may be useful for the diagnosis of biliary tract cancers, although it may be effectively limited to patients with advanced disease.

Base Sequence↗
PubMed1999

Dynamics of nitrotyrosine formation and decay in rat brain during focal ischemia-reperfusion.

The purpose of this study was to establish the dynamics of nitrotyrosine (NO2-Tyr) formation and decay during the rise of NO2-Tyr in rat brain subjected to 2-hour focal ischemia-reperfusion, and to evaluate the role of inducible nitric oxide synthase in the rise. The authors first determined the half life of NO2-Tyr in rat brain at 24 hours after the start of reperfusion by blocking NO2-Tyr formation with N(G)-monomethyl-L-arginine and after the decay of NO2-Tyr by means of a hydrolysis/HPLC procedure. The values obtained were approximately 2 hours in both peri-infarct and core-of-infarct regions. Using the same hydrolysis/HPLC procedure, the ratio of nitrotyrosine to tyrosine from the 2-hour occlusion to as much as 72 hours after the start of reperfusion was measured in the presence and absence of aminoguanidine (100 mg/kg intraperitoneally twice a day). In the absence of aminoguanidine, the ratio of NO2-Tyr in the peri-infarct and core-of-infarct regions reached 0.95% +/- 0.34% and 0.52% +/- 0.34%, respectively, at 1 hour after the start of reperfusion. The elevated levels persisted until 48 hours, then declined. The peri-infarct region showed the highest percent NO2-Tyr level, followed by the core of infarct, then the caudoputamen. Aminoguanidine significantly reduced NO2-Tyr formation (up to 90% inhibition) during 24 to 48 hours. The authors conclude that inducible nitric oxide synthase is predominantly responsible for NO2-Tyr formation, at least in the late phase of reperfusion. These results have important implications for the therapeutic time window and choice of nitric oxide synthase inhibitors in patients with cerebral infarction.

Animals↗
PubMed1999

Suppression and enhancement of the Freund's incomplete adjuvant-induced writhing reaction by sodium ascorbate in mice.

We noticed that an intraperitoneal injection of Freund's incomplete adjuvant (FIA) into mice could stimulate the induction of a writhing reaction. The FIA emulsion-induced writhing reaction was found to be remarkably inhibited by preadministration of oral indomethacin, a non-steroidal anti-inflammatory and analgesic drug. The induction of the writhing reaction was also inhibited by intravenous preadministration of sodium ascorbate (SAs) in saline. In the experiments where SAs was added to FIA, it was demonstrated that SAs had dual activity of suppression and enhancement. At lower concentrations SAs functioned as a suppressor of the writhing reaction, while at concentrations higher than about 1 mg/50 microl/mouse it acted as an enhancer of the reaction. Furthermore, this writhing reaction induced by FIA+SAs emulsion was also inhibited by preadministraion of SAs itself as well as indomethacin. These results suggested that the mechanism of the writhing reaction induced by FIA was concerned with the production of prostaglandins (PGs), and SAs might be involved in regulation of the writhing reaction. In this paper, we propose a mouse writhing model induced by FIA or FIA+SAs emulsion as a novel pain model useful for assessment of analgesic and anti-inflammatory agents.

Analgesics↗
PubMed1999

Detection of anaphylactic reaction in the percutaneously sensitized mouse using the AW method.

Anaphylactic reactions of mice sensitized percutaneously with 2,4-dinitrofluorobenzene (DNFB) were investigated by the AW method assay, which is a mouse anaphylactic model using the abdominal wall as the site for induction with either 2,4-dinitrophenyl (DNP)-human serum albumin or anti-mouse IgE antibody and then estimation of the response. DNP-specific and IgE-dependent anaphylactic reaction after contact sensitization with DNFB could be induced and detected by the abdominal wall (AW) method assay in both groups with and without previous ear challenge with DNFB. Thus, the anaphylactic reaction in the group of twice-contact with 0.5% DNFB was observed on the 9th day from the sensitization (5th day from the ear challenge), and the reaction in the group of a single contact with 0.5% DNFB was observed 10 d after sensitization. The DNP-specific anaphylactic reaction was observed earlier than the 10th day with higher doses of DNFB. As for the mice of the former twice-contact group, the first and second characteristic ear swelling responses appeared within 1-6 h and 2 d of the ear challenge, respectively, and small swelling was observed 7 d after the challenge. It is suggested that Th1 and Th2 cells are activated at the almost same time, in other words, the preparation for both cell-mediated and humoral immunity could be accomplished to function, in vivo by a single percutaneous sensitization with DNFB.

Abdominal Muscles↗
PubMed1999

Rotational cine cholangiography: evaluation for use in diagnosing bile duct carcinoma.

OBJECTIVE: We evaluated the usefulness of rotational cine cholangiography in the preoperative diagnosis of bile duct carcinoma. SUBJECTS AND METHODS: Rotational cine cholangiography was performed in both the transverse and cephalad anterior oblique planes in 60 patients with obstructive jaundice. Using strict diagnostic criteria, the capability of this technique to detect the confluence of the right hepatic duct and the left hepatic duct, the right anterior segmental duct and the right posterior segmental duct, and the left medial segmental duct was investigated. The angle at which the confluence was revealed was also investigated. In 26 patients with resected bile duct carcinomas, the preoperative diagnosis of cancer spread obtained using this procedure was compared with the histopathologic findings. RESULTS: Overall detectabilities of the confluences of the right hepatic ducts and left hepatic ducts, the right anterior segmental ducts and right posterior segmental ducts, and the left medial segmental ducts were 97.6%, 87.0%, and 93.1%, respectively. The angles of the confluences of the right hepatic ducts and left hepatic ducts and of the right anterior segmental ducts and right posterior segmental ducts were widely distributed: on the other hand, those of the left medial segmental ducts were distributed mainly from 0 degrees to 20 degrees . The accuracies of diagnosis of cancer invasion were 91.7% in the common hepatic ducts, 100% in the right hepatic ducts, 91.7% in the left hepatic ducts, 100% in the right anterior segmental ducts, 83.3% in the right posterior segmental ducts, and 100% in the left medial segmental ducts. CONCLUSION: Rotational cine cholangiography is reliable not only in detecting the confluence of the bile ducts but also in diagnosing the longitudinal extent of cancer spread along the bile duct wall.

Aged↗
PubMed1999

Clinical, pathological and mineralogical features in two autopsy cases of workers exposed to agalmatolite dust.

An agalmatolite miner and processor showed large shadows at the bilateral hila accompanied by surrounding emphysematous changes and irregular shadows on chest X-ray films. Chest CT scans were characterized by a mixture of tiny irregular structures and small round opacities. Histopathological examination revealed massive fibrosis, which corresponded to large shadows, but only a small number of typical silicotic nodules, indicating mixed dust pneumoconiosis. Mineralogical examination of the autopsy lungs showed quartz, pyrophyllite, mica, and kaolinite. Quartz accounted for 70% of the amount of all mineral dust in both patients, but pyrophyllite accounted for 10.8% and 14.4%. The pulmonary mineral dust composition in the two patients was well consistent with the mineral composition of the raw clays in the agalmatolite mine. In the two patients, chest X-ray findings and histopathological findings of the lungs also suggested agalmatolite pneumoconiosis, which was confirmed by mineral analysis of the lungs.

Aged↗
PubMed1999

Detection of telomerase activity in exfoliated cancer cells obtained from bile.

Telomerase is detected by the telomeric repeat amplification protocol (TRAP) assay in more than 85% of primary cancers. In the present study, we determined telomerase activity using exfoliated bile cells obtained from biliary tract neoplasia specimens. The aim of this study was to provide additional information regarding minimally invasive approaches to the detection of biliary tract cancer in combination with routine cytologic examination. We analyzed for telomerase activity bile juice from patients with gallbladder carcinoma, cholangiocarcinoma, cholecystitis and cholangitis. Semiquantitative determination of telomerase activity was performed using both a fluorescence-based TRAP assay on cell extracts and at the cellular level by an in situ TRAP assay. The fluorescence-based TRAP assay detected bile telomerase activity in samples from 4 of 10 patients with biliary tract cancer. In contrast, the in situ TRAP assay detected telomerase positive cells in samples from 6 of 10 patients with biliary tract cancer. However, only one of these samples showed class V cytology. A combination of semiquantitative analysis and an in situ TRAP assay to detect telomerase positive cells may improve the diagnosis of biliary tract cancers with the combination of routine cytologic examination.

Adult↗
PubMed1999

[Endovascular treatment of ruptured intracranial aneurysms using platinum coils in patients over 80 years of age].

Endovascular treatment of intracranial aneurysms using plantinum coils was performed in 10 patients over 80 years of age. The patients ranged in age from 81 to 96 years. Preoperative Hunt and Kosnik grading revealed one patient in grade I, 4 in grade II, 3 in grade III, and 2 in grade IV. The aneurysms were located in the internal carotid artery in 6 patients, in the anterior communicating artery in 1, and in the middle cerebral artery in 3 respectively. Intra-aneurysmal occlusion was accomplished in 8 patients with total or subtotal occlusion in 6 and partial occlusion in 2. In one patient with a peripheral middle cerebral artery aneurysm, the parent artery was occluded just proximal to the aneurysm. In the remaining one patient in grade III, an aneurysm associated with wide neck could not be occluded because of coil protrusion into the parent artery. In 9 patients who were successfully treated, all five patients in grade I or II and one in grade III resulted in good outcome, but the other three patients in grade III and IV showed poor outcome. No evidence of recurrent hemorrhage was noted during the follow-up period ranging from 2 months to 4 years. Endovascular coil embolization is a useful therapeutic alternative for treating ruptured intracranial aneurysms in patients over 80 years of age, especially those in Grade I or II.

Aged↗