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H Toyoda

Publications and source records attributed to H Toyoda.

At least 127 records · Page 7Linked to original sources
PubMed1999

A comparative study of postoperative complications after hepatectomy in patients with and without chronic liver disease.

BACKGROUND: Although hepatic resection is the most reliable treatment for hepatocellular carcinoma, impaired liver function because of cirrhosis or chronic hepatitis contributes to relatively high rates of postoperative complications. We have reviewed a series of hepatectomies at our institution and investigated risk factors for complications after hepatectomy in patients with impaired liver compared with patients with normal liver. METHODS: From October 1994 to March 1998, 277 hepatectomies for hepatocellular carcinoma, cholangiocellular carcinoma, metastatic liver tumors, and other hepatic diseases were performed. In an attempt to clarify the safety of hepatectomy for the impaired liver at our institution, we did a comparative study of postoperative complications after hepatectomy in 2 groups: patients with impaired livers (187 hepatectomies) and patients with normal livers (90 hepatectomies). RESULTS: Of the 277 hepatectomies, bile leakage occurred in 25 patients (16 in impaired livers vs 9 in normal livers), abdominal infection in 45 patients (30 vs 15 patients), wound infection in 13 patients (9 vs 4 patients), pleural effusion in 52 patients (35 vs 17 patients), atelectasis in 26 patients (17 vs 9 patients), pneumonia in 4 patients (3 vs 1 patients), ileus in 6 patients (3 vs 3 patients), intra-abdominal hemorrhage in 3 patients (0 vs 3 patients), and hyperbilirubinemia in 5 patients (4 vs 1 patients). Hepatic insufficiency and hospital death were not experienced in this series. The mean postoperative hospital stay was 22.9 days (23.5 vs 23.1 days), and except for intra-abdominal hemorrhage there was no statistically significant difference between the 2 groups. CONCLUSIONS: Hepatectomy for the impaired liver is now as safe a procedure as for the normal liver, provided the overall guidelines outlined in our algorithm are followed.

Adolescent↗
PubMed1998

Effect of GB virus C/hepatitis G virus coinfection on the course of HIV infection in hemophilia patients in Japan.

OBJECTIVE: A novel virus, GB virus C (GBV-C)/hepatitis G virus (HGV), has been isolated. This virus is parenterally transmissible, but its effect on various diseases remains to be disclosed. We investigated the effect of GBV-C/HGV coinfection on the course of HIV infection. METHODS: GBV-C/HGV RNA was measured by nested reverse transcription polymerase chain reaction (RT-PCR) in 41 HIV-infected hemophilia patients in Japan. Patient characteristics, HIV RNA concentrations, and rates of progression to AIDS and to death were compared in patients with and without GBV-C/HGV coinfection. HIV RNA was quantified by the Amplicor HIV Monitor test (Roche Molecular Systems, Somerville, NJ, U.S.A.), and progression to AIDS and to death was analyzed using Kaplan-Meier plots. RESULTS: GBV-C/HGV infection was present in 11 of 41 of patients (26.8%). Mean HIV RNA concentration was lower in patients with GBV-C/HGV coinfection (3.52+/-4.81 x 10(4) copies/ml) than in patients without coinfection (5.76+/-14.78 x 10(4) copies/ ml) and progression to AIDS and to death were slower in patients with GBV-C/HGV coinfection than patients without it, although the differences were not statistically significant. CONCLUSION: In Japanese hemophilia patients, coinfection with GBV-C/HGV does not have an adverse effect on the course of HIV infection.

Adolescent↗
PubMed1998

Anti-EGFR monoclonal antibodies which act as EGF, TGF alpha, HB-EGF and BTC antagonists block the binding of epiregulin to EGFR-expressing tumours.

Epiregulin is the newest member of the epidermal growth factor (EGF) family of ligands that was isolated from conditioned medium of the murine fibroblast-derived tumour cell line NIH3T3/T7. Here, using a panel of anti-EGFR receptor (EGFR) monoclonal antibodies (MAbs) directed against 4 distinct epitopes on the external domain of the receptor, we have investigated the importance of the EGFR in transmitting the biological action of epiregulin. We found that MAb ICR9, which enhances the binding of EGF, TGF alpha, HB-EGF and betacellulin to the EGFR, also increases the binding of 125I-epiregulin to a number of EGFR-expressing tumour cell lines, including EJ, SKBR3, SKOV3, MDA-MB468 and HN5. In addition, anti-EGFR MAbs ICR15, ICR16, ICR61, ICR62 and ICR80, which block the binding of 125I-EGF to the EGFR, inhibit the binding of 125I-epiregulin to these tumour cell lines. Like EGF, we found that both the epiregulin-induced growth inhibition of HN5 and MDA-MB468 cells and tyrosine phosphorylation of the 170 kDa EGFR on HN5 cells are reversed in the presence of anti-EGFR MAbs ICR62 and ICR80. Surprisingly and unlike 125I-EGF, radiolabelled epiregulin bound very poorly to human bladder carcinoma EJ cells and its binding to SKOV3 cells was not inhibited efficiently in the presence of blocking antibodies. We conclude that the EGFR plays an important role in transmitting the biological action of epiregulin and that these effects could be blocked in the presence of anti-EGFR MAbs. The low level of binding of epiregulin compared with EGF to EJ cells suggests that the EGFR may not be the primary receptor for epiregulin.

3T3 Cells↗
PubMed1998

Contribution of T cells to the development of autoimmune diabetes in the NOD mouse model.

The nonobese diabetic (NOD) mouse spontaneously develops an autoimmune diabetes that shares many immunogenetic features with human insulin-dependent diabetes mellitus (IDDM), type 1 diabetes. The mononuclear cell infiltrates in the islet, which results in the development of insulitis (a prerequisite step for the development of diabetes) are primarily composed of T cells. It is now well accepted that these T cells play important roles in initiating and propagating an autoimmune process, which in turn destroys insulin-producing islet beta cells in the pancreas. T cells are subdivided into CD4+ helper T cells and CD8+ cytotoxic T cells. CD4+ T cells are further subdivided into Th1 and Th2 cells based on profiles of cytokine production, and these two T-cell populations counterregulate each other. Because many autoimmune diseases are Th1 T-cell mediated, current studies have focused on manipulating the Th1/Th2 imbalance to suppress the autoimmune process in the NOD model. Furthermore, the incidence of disease is much higher in females than that in males, suggesting an involvement of sex-steroid hormones in the development of diabetes. Understanding insights of the mechanism of immune-mediated islet cell destruction and the interaction between the immune and the neuroendocrine system may, therefore, provide new therapeutic means of preventing this chronic debilitating disease.

Animals↗
PubMed1998

Overexpression of manganese-superoxide dismutase prevents methylmercury toxicity in HeLa cells.

HeLa cells were stably transformed with plasmid constructs that allowed constitutive expression of antioxidant enzymes such as catalase, glutathione peroxidase (GSH-Px), Cu,Zn-superoxide dismutase (Cu,Zn-SOD) or Mn-superoxide dismutase (Mn-SOD) to examine the involvement of reactive oxygen generation in methylmercury toxicity. Overexpression of catalase, GSH-Px or Cu,Zn-SOD did not affect the sensitivity of HeLa cells against methylmercury. However, the sensitivity of HeLa cells against methylmercury was decreased by overexpression of Mn-SOD, an enzyme localized in matrix of mitochondria and which decomposes superoxide anions. These results suggest that formation of superoxide anions in the mitochondria might be involved in the mechanism of the cytotoxicity of methylmercury.

Catalase↗
PubMed1998

Assessment and treatment of liver disease in Japanese haemophilia patients.

We studied the prevalence of the hepatitis C virus (HCV), human immunodeficiency virus (HIV) and GB virus C or hepatitis G virus (GBV-C/HGV), and characteristics of infections in Japanese haemophilia patients. Haemophilia patients were highly infected with HCV (88.2%) because of frequent use of unheated blood concentrates. Analysis for HCV genotypes revealed characteristics of HCV infection in haemophilia patients. Japanese haemophilia patients were highly infected with rare genotypes in Japan: genotype 1a (26.5%), genotype 3 (14.5%) and genotype 4 (2.4%). HIV infection was observed in 32.3% of haemophilia patients. HCV quasispecies (clones) and direct sequencing were investigated in patients with a single HCV genotype in the hypervariable region 1 of HCV, which resulted in a high degree of diversity. This indicates that even a single genotype of HCV might have multiple origins. GBV-C/HGV infection was noted in 20.9% of Japanese haemophilia patients. Over 40 haemophilia patients with chronic hepatitis C have been treated with interferon alpha for 6 months at total doses of 480-720 million units. About 38% showed clearance of HCV RNA from serum. Six patients with HIV infection were included in the study and they did not show eradication of HCV from the serum. This might derive from that they had high serum HCV RNA titers and genotype 1a or 1b. Histologic assessment was performed in 36 haemophilia patients with HCV. No case showed a histologically normal liver. Hepatic fibrosis in the biopsy specimens was classified into five stages of fibrosis and compared with serum hepatic fibrosis markers. Serum hyaluronic acid mostly correlated with hepatic fibrosis (r = 0.78, P < 0.0001) followed by type IV collagen (r = 0.38, P < 0.05). This suggests that estimation of serum fibrosis markers might be substituted for liver biopsy in haemophilia patients.

HIV Infections↗
PubMed1998

Characteristics of patients with chronic infection due to hepatitis C virus of mixed subtype: prevalence, viral RNA concentrations, and response to interferon therapy.

We studied 349 patients with chronic infection due to hepatitis C virus (HCV), including 83 with coagulopathy, 122 with community-acquired infection, 20 with chronic posttransfusion hepatitis C, and 124 for whom the transmission mode was unknown. The prevalence of mixed-subtype HCV infection was investigated in each group of patients. The serum HCV RNA concentration and the response to interferon (IFN) therapy were evaluated. HCV infection with mixed subtypes was more frequent in patients who had been at high risk for exposure to HCV, such as those with coagulopathy or community-acquired infection. HCV RNA concentrations were lower in patients infected with mixed subtypes, except for those with subtypes 1a and 1b. Ten of 11 patients with mixed subtypes (not including those with 1a and 1b) achieved complete clearance of HCV RNA with IFN therapy.

Adolescent↗
PubMed1998

Prophylactic endoscopic ligation of high-risk oesophageal varices in a cirrhotic patient with severe haemophilia A.

One of the main complications in cirrhosis is haemorrhage from oesophageal varices. It is serious and often fatal, especially in cirrhotic patients with haemophilia. We describe the use of endoscopic variceal ligation (EVL) for prophylaxis of oesophageal variceal bleeding in a high-risk patient, a 40-year-old Japanese man, with severe haemophilia A and liver cirrhosis caused by hepatitis C virus. He had large, coil-shaped varices with a red colour sign, predicting the likelihood of haemorrhage. Administration of omeprazole and factor VIII concentrate achieved rapid healing of the post-EVL ulcers and prevented bleeding from them. Four EVL sessions eradicated oesophageal varices completely, and he has had no recurrence of varices for 2 years, indicating that the procedure was of considerable benefit.

Adult↗
PubMed1998

Characterization and determination of human urinary keratan sulfate.

Keratan sulfate was isolated from normal human urine and was characterized by sugar compositional analysis and H-NMR spectroscopy. It was found that KS from human urine is classified as skeletal type (KS-II type chain) with an O-glycosidic linkage between galactosamine and serine (or threonine). H-NMR studies revealed that urinary KS is not a proteoglycan but a polysaccharide (molecular weight is about 5 kDa). The quantitation of human urinary KS by HPLC showed that urinary KS is excreted at constant levels (0.07 +/- 0.015 microgram/mg creatinine).

Carbohydrates↗
PubMed1998

Methylmercury-induced microtubule depolymerization leads to inhibition of tubulin synthesis.

Methylmercury (MeHg) specifically depolymerizes microtubules and inhibits cell proliferation in mouse glioma cells. The effect of microtubule depolymerization by MeHg on tubulin synthesis was studied. Tubulin synthesis analyzed by two-dimensional electrophoresis using [35S]methionine as a tracer was markedly inhibited in mouse glioma cells exposed to 5 x 10(-6)M MeHg for 3 hr, which completely depolymerized microtubules. Under this condition, density of the protein bands other than tubulin in autoradiogram remained unchanged on gradient urea-polyacrylamide gels. Furthermore, the decrease in tubulin mRNA level was relevant to that in tubulin synthesis, although actin mRNA levels remained unchanged. In addition, specific transcription rates of beta-tubulin genes appeared to be unaffected under the same experimental condition as above. Thus, it is concluded that the disruption of microtubules by MeHg resulted in the inhibition of the synthesis of tubulin itself through autoregulatory repression in post-transcriptional processes as in the case of colchicine treatment.

Actins↗
PubMed1998

Quasispecies nature of hepatitis C virus (HCV) in patients with chronic hepatitis C with mixed HCV subtypes.

The quasispecies nature of hepatitis C virus (HCV) in patients with mixed HCV subtype infection was compared with that in patients with single HCV subtype infection. The number of HCV quasispecies was compared between 35 patients with mixed HCV subtype infection and 83 patients with single subtype infection. Subtype was determined by primers deduced from the core region and by line probe assay respectively. The number of quasispecies was evaluated by polymerase chain reaction amplification of hypervariable region 1 and by fluorescence single-strand conformation polymorphism analysis. There was no difference in clinical background between patients with mixed subtype infection and patients with single subtype infection. The number of quasispecies in patients with multiple subtype HCV infection was larger than in patients with single subtype HCV infection. The immunologic environments which allow the coexistence of more HCV quasispecies in patients with multiple HCV subtype infection differs from that in patients with single HCV subtype infection.

Adult↗
PubMed1998

Factor X Nagoya 1 and Nagoya 2: a CRM- factor X deficiency and a dysfunctional CRM+ factor X deficiency characterized by substitution of Arg306 by Cys and of Gly366 by Ser, respectively.

We have identified, in two unrelated patients, factor X deficiency that we have designated factor X Nagoya 1 and Nagoya 2, respectively. The proband with factor X Nagoya 1 showed factor X activity level of 3% and factor X antigen level < 10% of the normal control value. All the exons and intron/exon junctions of the factor X gene were studied using a strategy combining polymerase chain reaction (PCR) amplification and nonradioactive single-strand conformational polymorphism (SSCP) analysis. Exon 8 containing DNA fragment of the proband with factor X Nagoya 1 showed aberrant migration on SSCP analysis. All exon-containing DNA fragments amplified by PCR were sequenced, and we identified a C-to-T substitution in exon 8 in the human factor X gene of the proband, which results in the replacement of Arg306 by Cys. This genetic defect has been transmitted from her father, and her sister also carried the same mutation; both showed almost half the normal levels of both factor X activity and antigen. The coordinates of human factor Xa indicated that Arg306 in the catalytic domain is positioned at the beginning of the alpha-helix near the second EFG-like domain. The substitution for Arg of Cys has been supposed to cause the destruction of local alpha-helix formation, possibly leading to the secretion problem. The proband with dysfunctional factor X Nagoya 2 was characterized by factor X activity level of 34% with normal factor X antigen level of 80%. We identified one substitution of G for A in exon 8 in the human factor X gene of the proband, which results in the replacement of Gly366 by Ser. As the Gly366 is positioned at the primary substrate binding pocket. the replacement of Gly with Ser would cause a defect of substrate binding, leading to the loss of enzymatic activity.

Adult↗
PubMed1998

GB virus C/hepatitis G virus isolates in Japanese haemophiliacs and their origins.

Japanese haemophiliacs have been at high risk for infection with parenterally-transmissible viruses through the use of blood products, especially imported ones. Recently, novel transfusion-transmissible virus, GB virus C (GBV-C)/hepatitis G virus (HGV) were isolated. We investigated the origin and route of transmission of GBV-C/HGV isolates in haemophiliacs in Japan. GBV-C/HGV RNA was measured by nested reverse transcription polymerase chain reaction in 91 Japanese haemophiliacs. Phylogenetic analysis and genotypic grouping of GBV-C/HGV isolates in Japanese haemophiliacs were performed based on sequences in the 5' untranslated region, and the characteristics were compared with those of reported isolates. GBV-C/HGV infection was present in 19 of 91 haemophiliacs (20.9%). Sequence analysis showed that 15 of the 19 isolates (78.9%) showed sequence similarity to a group in which mainly West African isolates have been reported. The other 4 isolates (21.1%) showed sequence similarity to Asian isolates. None of the GBV-C/HGV isolates showed sequences similar to those generally found in isolates from USA and Europe. The majority of GBV-C/HGV isolates found in Japanese haemophiliacs who are considered to have been infected by imported blood products were similar to those detected in West Africa.

Adolescent↗
PubMed1997

Sensitive high-performance liquid chromatographic method with fluorometric detection for the determination of heparin and heparan sulfate in biological samples: application to human urinary heparan sulfate.

A sensitive high-performance liquid chromatographic method for the determination of unsaturated disaccharides produced from heparin and heparan sulfate is described. Heparan sulfate was depolymerized using a combination of heparin lyase I (EC 4.2.2.7), heparin lyase II and heparin lyase III (EC 4.2.2.8). Seven unsaturated disaccharides were separated under isocratic conditions within 25 min using acetonitrile-H2O-0.2 M sodium phosphate buffer (pH 7.0)-3.0 M ammonium chloride (32:10:1:1) and were monitored by fluorescence detection using 2-cyanoacetamide as a post-column derivatizing reagent. As little as 2 pmol of a disaccharide could be detected with excitation at 346 nm and emission at 410 nm. This method was applied to the analysis of normal human urine. It was revealed that the concentration of normal human urinary heparan sulfate is 1.53+/-0.36 mg/mg creatinine (n=4).

Adult↗
PubMed1997

Epiregulin binds to epidermal growth factor receptor and ErbB-4 and induces tyrosine phosphorylation of epidermal growth factor receptor, ErbB-2, ErbB-3 and ErbB-4.

Epiregulin is a member of the epidermal growth factor (EGF) family, and has certain characteristics that are different from that of EGF, including mitogenic responses and binding to EGF receptor (EGFR). Epiregulin may also have another cell surface receptor and/or induces different receptor heterodimerizations for intracellular signaling. We investigated the binding ability of epiregulin to four ErbB family receptors using four human breast carcinoma cell lines that expressed different subsets of receptors. Chemical cross-linking experiments showed that [125I]epiregulin directly bound to each of EGFR and ErbB-4 but not to ErbB-2 and ErbB-3. Furthermore, although epiregulin stimulated tyrosine phosphorylation of all four ErbB receptors, the main intracellular signal was mediated by ErbB-4 and/or EGFR. The pattern of activation of ErbB family receptors was different from that of other EGF-related ligands. Our findings indicate that ErbB-4 and EGFR are receptors for epiregulin, and suggest that EGF-related ligands transduce signals for different biological responses by the hierarchical mechanism.

3T3 Cells↗
PubMed1997

Detection of glycosaminoglycans as a copper(II) complex in high-performance liquid chromatography.

Glycosaminoglycans including heparin, heparan sulfate, chondroitin sulfate, dermatan sulfate and hyaluronan were analyzed by high-performance gel filtration chromatography. Detection was achieved at 240 nm based on the formation of copper(II) complex in copper sulfate solution at low pH. Detection of the copper(II)-heparin complex is sensitive, permitting the analysis of as little as 10(-7) g. This method was also successfully applied to the analysis of the chemically derivatized glycosaminoglycans (de-N-acetylated and/or oversulfated chondroitin sulfate) that cannot be depolymerized by enzymes such as heparin and chondroitin lyases.

Chelating Agents↗
PubMed1997

Chemical microdetermination of heparin in plasma.

A new, simple, and highly sensitive method for the determination of heparin has been established. Heparin was first converted into unsaturated disaccharides through the action of heparin lyases I, II, and III. A major trisulfated unsaturated disaccharide product results, consistent with structural analysis of a number of pharmaceutical heparins using one- and two-dimensional 1H NMR spectroscopy. This disaccharide was analyzed by HPLC using fluorometric postcolumn derivatization. The correlation between the amount of this trisulfated unsaturated disaccharide and anticoagulant activity of heparin as measured by anti-IIa was determined. The analysis of these pharmaceutical heparins showed a linear correlation between both HPLC and bioassay. This HPLC method was then applied to a pharmacokinetic study of heparin intravenously administered to rabbits.

Animals↗