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Y Miyakawa

Publications and source records attributed to Y Miyakawa.

At least 19 recordsLinked to original sources
PubMed1992

Antibodies against synthetic oligopeptides deduced from the putative core gene for the diagnosis of hepatitis virus infection.

Immunoassays were developed to detect antibodies against oligopeptides deduced from the putative core gene of hepatitis C virus, and their performances were compared with that of the commercial immunoassay for antibodies against the product of nonstructural regions of hepatitis C virus (anti-C100-3). A 19-mer oligopeptide (CP10) and a 36-mer oligopeptide (CP9) were chemically synthesized, which represented hydrophilic regions of the product of the hepatitis C virus core gene. They were used to capture corresponding antibodies, anti-CP10 and anti-CP9, by enzyme-linked immunosorbent assay in sera from patients with acute or chronic non-A, non-B liver disease and in blood donations. At the onset of acute non-A, non-B hepatitis, anti-CP10 was detected in 15 of 20 patients (75%), and anti-CP9 was detected in 14 patients (70%). This was more frequent than anti-C100-3, which was found in only 9 patients (45%). In 186 patients with chronic non-A, non-B liver disease, anti-CP9, anti-CP10 or both were detected in 170 patients (91%). This was more frequent than anti-C100-3, which was found in 138 patients (74%). Blood with anti-CP10 as the single serological marker for hepatitis C virus infection transmitted non-A, non-B hepatitis by needlestick exposure. In sera from 558 apparently healthy blood donors, anti-CP10 was detected in 55 donors (9.9%), anti-CP9 was detected in 26 donors (4.7%) and anti-C100-3 was detected in 7 donors (1.3%).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Hepatitis B surface antigen particles of subtypes adw and adr, and compound subtype (adwr) in symptom-free carriers in Japan.

Of sera from 1,878 Japanese blood donors who carried hepatitis B surface antigen (HBsAg), 420 were subtyped as adw (22.4%) and 1,443 as adr (76.8%); only 15 (0.8%) contained HBsAg of subtype ayw or ayr. Sera with HBsAg/adr had higher HBsAg titres than those with HBsAg/adw (geometric mean of haemagglutination titre: 10.1 +/- 2.4 vs. 9.7 +/- 2.4, p less than 0.01), and a higher prevalence of hepatitis B e antigen (24% vs. 13%, p less than 0.001). Carriers of HBsAg/adr progressively predominated over those of HBsAg/adw with increasing age. Of sera from 1,863 carriers of HBsAg/adw or HBsAg/adr, 182 (9.8%) contained HBsAg particles with both subtypic determinants in the w/r allele. The presence of w and r determinants on the same particles was ascertained by sandwiching them between monoclonal antibody with the specificity for w and that with the specificity for r. HBsAg particles of compound subtype (adwr) were found more often in sera with hepatitis B e antigen than those without it (145/403 [36.0%] vs. 37/1,460 [2.5%], p less than 0.001). Sera with HBsAg/adwr particles had HBsAg titres higher than those without them (12.4 +/- 1.9 vs. 9.7 +/- 2.3, p less than 0.001). HBsAg/adwr particles arise from phenotypic mixing of the S-gene product of wild-type virus and that of mutants with point mutations for subtypic changes. The results obtained indicated that HBV strains of subtype adr have a higher replicative activity than those of adw, and suggested that mutations in the S gene for subtypic changes would be associated with an active replication of hepatitis B virus.

Adult↗
PubMed1992

Typing hepatitis C virus by polymerase chain reaction with type-specific primers: application to clinical surveys and tracing infectious sources.

Based on variation in nucleotide sequence within restricted regions in the putative C (core) gene of hepatitis C virus (HCV), four groups of HCV have been postulated in a panel of 44 HCV isolates. They were provisionally designated types I, II, III and IV. A method for typing HCV was developed, depending on the amplification of a C gene sequence by polymerase chain reaction using a universal primer (sense) and a mixture of four type-specific primers (antisense). HCV types were determined by the size of the products specific to each of them. Type II was found in HCV samples from 131 (82%) of 159 blood donors, more often than in those from 48 (60%) of 80 patients with non-A, non-B (NANB) liver disease in Japan (P less than 0.01). In 11 haemophiliacs who had received imported coagulation factor concentrates, type I was found in five, as against type II in four. Double infection with two different HCV types was found in two patients with chronic NANB liver disease (types I and II; II and III) and two haemophiliacs (types I and II; I and III). HCV types were identical in mother and baby in each of two examples of perinatal transmission, and were also identical in donor and recipient in a case of accidental needle exposure.

Base Sequence↗
PubMed1992

Correlation between anti-HBc titers and HBV DNA in blood units without detectable HBsAg.

Hepatitis B virus (HBV) DNA was tested for in 294 blood units which had antibody against hepatitis B core antigen (anti-HBc) as the isolated serological marker of HBV infection. After amplification by polymerase chain reaction, HBV DNA was detected in 12 (6.9%) of 175 units that were positive for anti-HBc with hemagglutination inhibition titers greater than or equal to 2(6), significantly more often than in none of 119 units with titers less than or equal to 2(5) (p less than 0.01). These results indicate that the exclusion of blood units with isolated high-titer anti-HBc would be effective for further decreasing the risk of posttransfusion hepatitis B.

Base Sequence↗
PubMed1992

Antigenic role of stress-induced catalase of Salmonella typhimurium in cell-mediated immunity.

The ability of the H2O2-induced catalase of Salmonella typhimurium to induce cell-mediated immunity against S. typhimurium infection in mice was examined. When exponentially growing cells of S. typhimurium were treated with 20 microM H2O2, the cells resisted killing by 1 mM H2O2 and showed the induction of a new species of catalase in addition to the constitutively produced one. Two molecules of catalases in S. typhimurium were isolated from mutant strains: H2O2-induced catalase (catalase II, 320 kDa), from a regulatory gene-deficient oxyR1 mutant, and constitutive catalase (catalase I, 350 kDa), from a katG gene-deleted mutant. When mice were inoculated with a sublethal dose of live cells, an intensive protective immunity (100% survival at 3 weeks) after challenge with a virulent strain associated with the delayed-type footpad hypersensitivity (DTH) reactions to both catalase I and catalase II was induced. Conversely, mice immunized with formalin-killed virulent S. typhimurium did not elicit protective immunity or DTH to either catalase. When mice were immunized with catalase I or catalase II, an enhanced protection (to a certain extent: 50% survival at 3 weeks) was induced in mice immunized with catalase II associated with DTH which did not cross-react with catalase I but not in those given catalase I. These results suggest that H2O2-induced stress proteins, including catalase II, are the dominant antigens for cell-mediated immunity in live cells of S. typhimurium and that a burst of such stress proteins in live salmonellae in phagocytes is responsible for the induction of cell-mediated immunity that is largely involved in the protection of susceptible mice against Salmonella infection.

Animals↗
PubMed1992

Role of specific determinants in mannan of Candida albicans serotype A in adherence to human buccal epithelial cells.

Candida albicans serotype A (C. albicans A) possesses a specific antigen, designated antigen 6, which resides in mannans on the cell surface. To determine the role of the mannan moiety of the C. albicans cell wall in adherence to buccal epithelial cells, we used antigen 6-deficient mutants which had been isolated by screening with an agglutinating monoclonal antibody against antigen 6 (MAb-6). 1H nuclear magnetic resonance spectral analysis of the purified mannans from the mutants showed a loss of the signals related to that beta-linkage of the side chains. Moreover, acetolyzed fragments of the mutant mannans showed a decreased amount of mannohexaose and mannopentaose. The mutant yeast cells exhibited significantly reduced ability to adhere both to exfoliated buccal epithelial cells and to a human buccal cell line. A number of strains of C. albicans A, C. tropicalis, and C. glabrata, all of which bear antigen 6, showed significantly higher adherence to the cell line than did those of C. albicans serotype B, which lack antigen 6. The whole mannan from the C. albicans A parent inhibited the adherence of C. albicans A to epithelial cells dose dependently, whereas mannan from a mutant strains did not. Moreover, C. albicans A treated with MAb-6 or polyclonal factor 6 serum showed reduced adherence. A close correlation was found between adhesive ability and agglutinability with MAb-6 in the C. albicans A parent, the antigenic mutants, and their spontaneous revertants. These results suggest that so far as mannan adhesion is concerned, serotype A-specific determinants are largely involved in the mechanisms of adherence of C. albicans A to human buccal epithelial cells.

Adhesiveness↗
PubMed1992

Isolation and characterization of a species-specific DNA fragment for detection of Candida albicans by polymerase chain reaction.

A 2-kbp DNA fragment, EO3, that was present in multiple copies in the Candida albicans genome was isolated for use in developing a detection method for C. albicans by polymerase chain reaction (PCR). Dot blot hybridization revealed that EO3 was specific for the 40 isolates of C. albicans serotypes A and B used. Using a set of primers (20-mer each) derived from the nucleotide sequence of EO3, we performed specific amplification of a 1.8-kbp DNA fragment within EO3 by PCR. All 40 isolates belonging to C. albicans serotypes A and B contained amplifiable 1.8-bkp fragments, although the DNA of the amplified products exhibited small variations in size, yielding three different fragment groups. Southern blot hybridization probed with EO3 showed that these 1.8-kbp fragments were derived from the EO3 region. Conversely, the 1.8-kbp fragment was not amplified from 38 isolates belonging to seven other medically important Candida species or from isolates of Cryptococcus neoformans, Saccharomyces cerevisiae, various bacteria, and a human cell line. The detection limit of the PCR assay for C. albicans with the EO3 fragment was shown to be approximately 2 to 10 cells and 100 cells in saline and human urine, respectively, by ethidium bromide staining and 2 and 10 cells, respectively, by Southern blot analysis. In addition, EO3 was assumed to originate from mitochondrial DNA on the basis of the results of its characterizations. These results indicate that the PCR system using the 1.8-kbp fragment as a target is a reliable method for identifying C. albicans isolates, thereby suggesting its potentials for specific and sensitive detection of C. albicans in samples from patients with candidiasis.

Base Sequence↗
PubMed1992

A study of the effects of manidipine on the diurnal variation of arterial pressure and hemodynamics in patients with essential hypertension.

In order to investigate the effects of manidipine, a newly developed long-acting calcium antagonist, on the diurnal variation of arterial pressure and systemic hemodynamics in patients with essential hypertension, we examined 24-h arterial pressure using a direct arterial pressure monitoring method and cardiac output using the cuvette method before and during manidipine treatment. Once-a-day administration of manidipine at daily doses of 10 to 40 mg decreased systolic and diastolic arterial pressures at almost all measurement points. The arterial pressure reductions were not significantly different between daytime and nighttime. Arterial pressure variability expressed in terms of the standard deviation of values was not affected by manidipine treatment. Thus, it appears that patients treated with manidipine can avoid the excessive decrease in arterial pressure during nighttime that may occur with the use of some other calcium antagonists. Heart rate and its variability were unaffected by manidipine treatment. A hemodynamic study revealed that manidipine did not change cardiac output, but significantly decreased total peripheral vascular resistance at rest. It is concluded that once-a-day administration of manidipine at daily doses of 10 to 40 mg brings about a safe and stable antihypertensive effect over a 24-h period, without affecting the diurnal variation of arterial pressure and heart rate. Dilation of the resistance vessels underlies the antihypertensive effect of the agent.

Adult↗
PubMed1991

Molecular heterogeneity of e antigen polypeptides in sera from carriers of hepatitis B virus.

Hepatitis B e Ag (HBeAg) was isolated from pooled sera of carriers, without abnormalities in liver function, by affinity column chromatography with mAb against HBeAg. HBeAg polypeptide with an estimated molecular size of 20,000 Da (p20e) was detected, in addition to regular HBeAg polypeptides (p17e/p18e). p20e, as well as p17e/p18e, did not bind with mAb against the carboxyl-terminal domain of the C-gene product. p20e disclosed an N-terminal sequence of MQLFHLXLII- (X unknown), whereas p17e had that of SKLXLGXLXGMDIDPXKEFG- (X's unknown). By comparing them with the amino acid sequence encoded by the precore region and C gene of hepatitis B virus DNA, p20e was deduced to possess amino acids 1 to 19 of the precore-region product at the N-terminus, which contains signal sequence and usually removed before the secretion of HBeAg. p17e had amino acids 20 to 29 of the precore-region product that continued to the C-gene product. Inasmuch as p20e was invariably detected in HBeAg preparations from carriers without evidence for liver disease, it would not have been released into the circulation from destructed hepatocytes. HBeAg polypeptide bearing an uncleaved signal sequence would help in further understanding the mechanism of HBeAg secretion.

Amino Acid Sequence↗
PubMed1991

Initiating activity of eight pyrolysates of carbohydrates in a two-stage mouse skin tumorigenesis model.

Tumor initiating potential was tested for eight pyrolysates of carbohydrates in a two-stage mouse skin carcinogenesis model using 12-O-tetradecanoylphorbol-13-acetate (TPA) as the promoter. The pyrolysates were levoglucosan (LG-I), levoglucosenone (LG-II), furfural (FF), 5-(hydroxymethyl)-2-furfural (HMF), glyoxal (GL), methylglyoxal (MGL), 3-deoxy-D-glucosone (DG) and thiazolidine (TZ). The total initiating doses were 200 mumol for LG-I and DG, 25 mumol for LG-II and 500 mumol for FF, HMF, GL, MGL and TZ. 7,12-Dimethylbenz[a]anthracene (DMBA) was used as a positive control agent applied to a total dose of 100 micrograms. All compounds were topically administered to the dorsal skin twice weekly for 5 weeks with or without TPA treatment for the following 47 weeks. In conjunction with promotion TZ induced skin tumors in 40% of the mice (average 0.65 tumors/mouse), FF in 25% (0.40/mouse), LG-I in 25% (0.35/mouse) and LG-II, HMF, DG and GL in 10-20% (0.11-0.25/mouse) respectively whereas DMBA induced skin tumors in 100% of the animals (6.7/mouse). MGL did not induce any tumors during the experiment and no tumors appeared in any of the groups treated with test chemicals alone. As assessed by Fisher's exact test, tumor incidences were significant in the TZ (0.01 less than P less than 0.05) and DMBA (P less than 0.01) groups as compared with the dimethylsulfoxide (DMSO) followed by TPA groups (5%, 0.05/mouse). Statistical analyses with Peto's trend test revealed significant tumor development in the LG-I (P less than 0.01), LG-II (0.05 less than P less than 0.01), FF (0.01 less than P less than 0.05) and TZ (P less than 0.01) followed by TPA groups (compared with DMSO + TPA). The results indicate that LG-I, LG-II, FF and TZ potentially possess tumor initiating activity, while HMF, GL, MGL and DG do not, as judged by the statistical analysis based on the incidences and development of the skin papillomas and/or carcinomas. A positive correlation between tumor initiating potential and clastogenic activity based on calculated ID50 (50% initiating dose) and published CD20 (20% clastogenic dose) values was evident for LG-II, FF and TZ, while LG-I was an exception.

Animals↗
PubMed1991

Nucleotide sequence of the genomic RNA of hepatitis C virus isolated from a human carrier: comparison with reported isolates for conserved and divergent regions.

The complete nucleotide sequence of a hepatitis C virus derived from plasma of a human carrier in Japan was determined. The cDNA of the isolate (HC-J6) contained 9481 nucleotides and an additional T stretch of 30 to 108 nucleotides at the 3' end, and had one large open reading frame coding for a polyprotein of 3033 amino acids. It differed by 31.8 to 32.1% in the nucleotide sequence and by 27.4 to 27.7% in the amino acid sequence from an American isolate and two Japanese isolates previously reported. Among these four isolates, the 5' non-coding region of 329 to 341 nucleotides was well conserved (greater than 93% identity), whereas the 3' non-coding region of 39 to 45 nucleotides (T stretches not included) was more variable (greater than 30% identity). An excellent degree of conservation of the 5' non-coding region would reflect its pivotal role in replication, and primers deduced from this region could be applied for the sensitive and specific detection of viral RNA by polymerase chain reaction. Due to a high degree of similarity in the amino acid sequence of the putative core protein (greater than 90%), antigen probes deduced from it would be suitable for the serological diagnosis of HCV infection. Low sequence similarity in the putative envelope protein (greater than 53% identity), however, would have to be taken into account in considering the immunoprophylaxis of HCV infection.

Amino Acid Sequence↗
PubMed1991

Posttransfusion fulminant hepatitis B associated with precore-defective HBV mutants.

Fulminant hepatitis B developed in 8 recipients of blood units without detectable hepatitis B surface antigen on routine screening. All 124 hepatitis B virus (HBV) DNA clones propagated from their sera possessed defects in the precore region. A point mutation from guanine to adenine at nucleotide 83, converting codon 28 for tryptophan (TGG) to a stop codon (TAG), was the commonest, and it was found in all 113 clones from 7 cases. The remaining case displayed 1 clone with this point mutation and 10 clones with an insertion of 2 base pairs after nucleotide 26. Antibody to hepatitis B core antigen (anti-HBc) was detected in a high titer in 1 of 10 pilot plasma samples of blood units transfused to this case. HBV DNA clones propagated from it exhibited the same precore-region defects as those from the recipient. On the basis of these results HBV mutants, defective in the precore region, would appear to be responsible for posttransfusion fulminant hepatitis B, and the exclusion of blood units with high-titered anti-HBc would be efficacious in preventing it.

Amino Acid Sequence↗
PubMed1991

Phosphorylation in the carboxyl-terminal domain of the capsid protein of hepatitis B virus: evaluation with a monoclonal antibody.

The capsid protein of hepatitis B virus (p21c) is made of 183 amino acids coded for by the C gene. By using p21c isolated from Dane particles (hepatitis B virus) as an immunogen, a monoclonal antibody (no. 2212) which recognized an epitope dependent on the phosphorylation of p21c was raised. The binding of no. 2212 antibody to authentic p21c was completely inhibited by a synthetic undecapeptide with a sequence of RRRSQSPRRRR, representing amino acids 165 to 175 of p21c, only when the peptide was phosphorylated. Either or both of Ser-168 and Ser-170 were phosphorylated in p21c in vivo, therefore, and contributed to the manifestation of the epitope. No. 2212 antibody bound to p21c from core particles derived from Dane particles or hepatocellular carcinoma tissues (PLC/342) propagated in nude mice but did not bind to p21c from core particles expressed in Escherichia coli or yeast cells, indicating different states of phosphorylation in them. Nonphosphorylated p21c showed a higher affinity for the viral DNA than did phosphorylated p21c. Since the serum from an asymptomatic carrier, with a high titer for antibody to hepatitis B core antigen, specifically bound to phosphorylated undecapeptide (amino acids 165 to 175), the epitope would stimulate humoral antibody responses in the human host.

Amino Acid Sequence↗
PubMed1991

Hepatitis B virus mutants with precore-region defects in two babies with fulminant hepatitis and their mothers positive for antibody to hepatitis B e antigen.

Clones of hepatitis B virus (HBV) DNA were propagated from sera of two babies who developed neonatal fulminant hepatitis B, as well as from sera of their mothers who carried HBV with antibody to hepatitis B e antigen, and the precore-region sequences were determined. A point mutation from guanine to adenine, converting codon 28 for tryptophan (TGG) to a stop codon (TAG), was detected in 18 of 20 HBV DNA clones from mother and all 31 clones from baby in one family, and invariably in 55 clones from mother and three clones from baby in the other family. These results indicate that HBV mutants defective in the precore region in some carrier mothers with antibody to hepatitis B e antigen may transmit fulminant hepatitis B to their babies.

Amino Acid Sequence↗
PubMed1990

Synthetic oligopeptides bearing a common or subtypic determinant of hepatitis B surface antigen.

Two determinants of hepatitis B surface Ag (HBsAg), identified by mAb raised against polypeptide components, were characterized immunochemically. One was expressed on HBsAg irrespective of the four major subtypes, i.e., adw, adr, ayw, and ayr, whereas the other was subtypic but not identical to any of d, y, w, and r determinants. The common determinant was generated by a synthetic pentadecapeptide with a sequence of Thr-Thr-Ser-Thr-Gly-Pro-Cys-Lys-Thr-Cys-Thr-Ile-Pro-Ala-Gln representing amino acids 115-129 of the S gene product, and detected invariably in 366 HBsAg samples in sera from asymptomatic carriers in Japan. The activity of the S gene product, as well as the peptide (115-129), to bind with the mAb was not affected by alkylation alone, but was completely lost after reductive alkylation. The antigenic activity was lost when the S gene product was severed between Lys122 and Thr123 by trypsin. A microconformation maintained by the -Cys121-Cys124 bond, therefore, would be required for the common determinant. The other mAb identified an epitope of HBsAg that was mimicked by a synthetic tetradecapeptide with a sequence of Thr-Cys-Thr-Ile-Pro-Ala-Gln-Gly-Thr-Ser-Met-Phe-Pro-Ser, representing amino acids 123-136 of the S gene product. Among 16 HBsAg samples with known S gene sequences, 5 with Ile126 possessed this subtypic determinant, but the remaining 11 with Thr126 did not. The 5 hepatitis B virus genomes encoding the subtypic determinant differed less than 5.6% from each other in the entire nucleotide sequence, but by 8.0% or more from any of the other 11 genomes without the capacity to encode it.

Alkylation↗
PubMed1990

Defects in the precore region of the HBV genome in patients with chronic hepatitis B after sustained seroconversion from HBeAg to anti-HBe induced spontaneously or with interferon therapy.

Hepatitis B virus DNA clones were propagated from sera of six patients with chronic hepatitis B who seroconverted from HBeAg to antibody to HBeAg either spontaneously or after administration of alpha-interferon. Defects in the precore region blocking synthesis and secretion of HBeAg were detected in all 46 hepatitis B virus DNA clones from three patients who remained positive for antibody to HBeAg and in whom hepatitis resolved. Defective clones had point mutations from guanine to adenine at nucleotide 83 in the precore region, converting codon 28 from tryptophan (TGG) to a stop codon (TAG). In contrast, this defect was not found in any of 39 hepatitis B virus DNA clones from three patients who seroconverted to antibody to HBeAg but then redeveloped HBeAg with reactivation of hepatitis. Using these results, the G-to-A point mutation at nucleotide 83 in the precore region would predict sustained positivity for antibody to HBeAg and remission of hepatitis in patients who have seroconverted either spontaneously or with interferon therapy.

Adult↗
PubMed1990

Isolation and characterization of feeding behavior mutants in Drosophila melanogaster.

Feeding behavior mutants of the fruit fly Drosophila melanogaster having point-mutations were isolated. The defects were analyzed in order to study the mechanism of feeding behavior. Point-mutations named febB (three allele) and febA (three allele) were located between the X-chromosome markers cho and cv and between the markers cv and v, respectively. The febB mutants showed a higher acceptance threshold of the proboscis extension reflex than wild-type flies and showed a normal chemosensory response to the electrophysiological test. The mutant (febB2) showed a higher starvation tolerance than the wild-type fly, but this was not a cause of the high acceptance threshold. Mosaic analysis was applied to the mutant. Internal tissues were suspected to be the primary focus of the abnormal behavior.

Animals↗