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Biomedical subjects

M Mayumi

Publications and source records attributed to M Mayumi.

At least 109 records · Page 6Linked to original sources

Reduced precore transcription and enhanced core-pregenome transcription of hepatitis B virus DNA after replacement of the precore-core promoter with sequences associated with e antigen-seronegative persistent infections.

Hepatitis B virus variants harboring nucleotide alterations in the preC-C promoter have been detected in fulminant hepatitis B as well as in HBeAg-seronegative persistent infection. However, it has not been demonstrated that variants with nucleotide alterations in the preC-C promoter cause various disease states. We replaced the preC-C promoter region of a wild-type genome with the most frequent naturally occurring mutated form and introduced it into HepG2 cells. The mutant with coexisting A1762T and G1764A substitutions produced less than one-fifth of the wild-type level of HBeAg. Conversely, the mutant generated 2.4 times more core particle antigen and showed a high-replicator phenotype. RNase protection and quantitative 5' RACE showed a 16- to 32-fold reduction of preC transcripts and a 4-fold induction of C transcripts of the mutant compared to wild-type. The preC transcript of the mutant had a more heterogeneous 5' end than that of the wildtype. However, the mutations did not alter the initiation sites of C transcription. When the promoter region was cloned into CAT plasmids, the mutations had dual effects on preC and C promoter activities, decreasing and increasing them, respectively. These results suggest that these mutations are responsible for the reduced HBeAg production as well as the enhanced replication and core production. Analysis of revertants with either single point mutation showed that T at 1762 is critical for the mutant phenotype.

Amino Acid Sequence↗

Infection with hepatitis GB virus C in patients on maintenance hemodialysis.

BACKGROUND: A recently discovered non-A-E hepatitis virus has been designated hepatitis GB virus C (HGBV-C), but little is known about its mode of transmission and its clinical manifestations. We studied 519 patients on maintenance hemodialysis to determine whether they were infected with HGBV-C. METHODS: HGBV-C RNA was identified in serum by a reverse-transcription-polymerase-chain-reaction assay with nested primers deduced from a non-structural region. A nucleotide sequence of 100 bp in the nonstructural region was determined on HGBV-C clones. RESULTS: HGBV-C RNA was detected on 3.1 percent of the patients on hemodialysis (16 of 519), as compared with 0.9 percent of healthy blood donors (4 of 448, P<0.03). None of the 16 patients had evidence of active liver disease, although 7 were also infected with hepatitis C virus. Eight patients with HGBV-C infection were followed for 7 to 16 years. In two patients the virus was present at the start of hemodialysis. One had a history of transfusion, and HGBV-C persisted over a period of 16 years; the other became free of HGBV-C after 10 years. In five patients, HGBV-C RNA was first detected 3 to 20 weeks after blood transfusion and persisted for up to 13 years. One patient with no history of transfusion was infected with an HGBV-C variant with the same sequence as in two of the patients with post-transfusion HGBV-C infections. CONCLUSIONS: Patients on maintenance hemodialysis are at increased risk for HGBV-C infection. This virus produces persistent infections, which may be transmitted by transfusions but may also be transmitted by other means.

Adult↗

Signal transduction pathway of interleukin-4 and interleukin-13 in human B cells derived from X-linked severe combined immunodeficiency patients.

Interleukin-4 (IL-4) and IL-13 are functionally similar cytokines. The functional IL-4 receptor (IL-4R) consists of the IL-4R alpha chain (IL-4R alpha) and the IL-2R gamma chain (gamma c), which is shared by the IL-2, IL-7, IL-9, and IL-15 receptors. The functional IL-13R is thought to involve the IL-4R alpha but not gamma c. In this study, we have analyzed activation of members of the Janus tyrosine kinase (Jak) family and signal transducers and activators of transcription (STAT) 6 induced by IL-4 and IL-13 in Epstein-Barr virus-transformed B cells derived from two patients of X-linked severe combined immunodeficiency, who have mutations of the gamma c gene in the extracellular and intracellular domains. In these B cells, IL-4 failed to induce tyrosine phosphorylation of Jak3 and activation of STAT6, or activation of these molecules was significantly decreased compared with Epstein-Barr virus-transformed normal B cells. In contrast, IL-13 activated STAT6 in these cells as well as normal B cells. However, Jak3 was not activated by IL-13, even in normal B cells. These results clearly indicated that gamma c is essential for activation of Jak3 and STAT6 in the signal transduction pathway of IL-4 in human B cells and that IL-13 does not utilize gamma c but activates STAT6 through an alternative pathway, which is not impaired in B cells of X-linked severe combined immunodeficiency patients.

B-Lymphocytes↗

Infection with GB virus C in leprous patients in Japan.

The detection of hepatitis C virus (HCV) in blood donors and patients with acute and chronic hepatitis has brought to the fore another virus or viruses which can be transmitted parenterally and induce liver disease. The RNA of a candidate virus designated GB virus C (GBV-C) was determined by the polymerase chain reaction with primers deduced from a helicase-like region in 229 leprous patients in Japan. GBV-C RNA was detected in 12 (5.2%) patients, and HCV RNA in 41 (18%). Three patients were coinfected with GBV-C and HCV. The nine patients infected with GBV-C alone had aminotransferase levels lower than the three patients with the mixed infection or the 38 patients infected with HCV only (P < 0.001). Sequence comparison within 100 base pairs in the helicase-like region suggested that two, three and three patients, respectively, would have been infected with three distinct strains of GBV-C. These results indicate that patients with leprosy are at increased risk for infection not only with HCV, but also with GBV-C, and that the infection with GBV-C alone would not induce hepatic injuries as severe as HCV infection.

Adult↗

Infection with GB virus C (GBV-C) in patients with chronic liver disease or on maintenance hemodialysis in Indonesia.

RNA of a non-A to E hepatitis virus identified recently and designated provisionally GB virus C(GBV-C), was sought in patients in Indonesia by reverse-transcription polymerase chain reaction with nested primers deduced from a helicase-like region. GBV-C RNA was detected in 32 (55%) of 58 patients on maintenance hemodialysis at a frequency significantly higher (P < 0.001) than that in seven (5%) of 149 patients with chronic liver disease. Co-infection with hepatitis C virus was observed in 26 (81%) of the 32 patients on hemodialysis and in five (71%) of the seven patients with liver disease who were infected with GBV-C. Complete identity was observed in a sequence of 100 base pairs in the helicase-like region for GBV-C cDNA clones from some patients on maintenance hemodialysis. These results indicate that the patients on hemodialysis would be at high risk for GBV-C infection, which would be transmitted by transfusion and patient-to-patient routes.

Antigens, Viral↗

HLA DRB1 and DQB1 alleles and haplotypes influencing the progression of hepatitis C.

Some HLA class II alleles and haplotypes were examined by restriction fragment length polymorphism of corresponding DNA fragments amplified by the polymerase chain reaction in 117 patients with chronic hepatitis C in Japan. The prevalence rates were compared between patients and 1216 controls and in 67 patients with liver cirrhosis, of whom 20 had hepatocellular carcinoma and 50 patients with chronic hepatitis who did not have cirrhosis or hepatocellular carcinoma. Notably, DRB1*0405 (49% [95% confidence range 38-60%] vs. 26% [16-40%]; P < 0.05, relative risk [rr] = 2.8) and DQB1*0401 (43% [33-54%] vs. 22% [13-34%]; P < 0.05, rr = 2.1) were detected more frequently in patients with cirrhosis than in those without cirrhosis. By contrast, DRB1*0901 (11% [6-19%] vs. 28% [18-40%]; P < 0.05; rr = 0.3) and DQB1*0303 (11% [6-19%] vs. 36% [25-49%]; P < 0.01; rr = 0.2) were detected less frequently in patients with cirrhosis than those without cirrhosis. Accordingly, the DRB1*0405-DQB1*0401 haplotype was more common (43% [33-54%] vs. 22% [13-34%]; P < 0.05; rr = 2.7), while the DRB1*0901-DQB1*0303 haplotype was less common (9% [4-17%] vs. 28% [18-40%]; P < 0.05; rr = 0.3) in patients with cirrhosis than in those without cirrhosis. These results suggest that there would be HLA class II alleles and haplotypes which may be associated with an accelerated or slower progression of chronic hepatitis C towards cirrhosis and eventually to hepatocellular carcinoma.

Alleles↗

A second-generation method of genotyping hepatitis C virus by the polymerase chain reaction with sense and antisense primers deduced from the core gene.

A second-generation method of genotyping hepatitis C virus (HCV) was developed by the polymerase chain reaction (PCR) with sense as well as antisense primers deduced from the core gene. HCV RNA specimens extracted from sera were reverse-transcribed and amplified with universal primers in the first round of PCR to obtain fragments of 433 base pairs representing nucleotides 319-751. In the second round of PCR, portions of PCR products were amplified separately with sense and antisense primers specific for each of the five common genotypes prevailing across the world, i.e., I/1a, II/1b, III/2a, IV/2b and V/3a. The specificity of the method was verified by a panel of 177 HCV isolates of various genotypes in the genetic groups 1-9. It allowed clear differentiation of genotype I/1a from II/1b which was not always accomplished by the previous method. When 501 sera from blood donors and hepatitis patients with HCV viremia from various countries were genotyped by the second-generation method, 478 (95.4%) were classified into the five genotypes. HCV RNA samples from 23 (4.6%) sera were not classifiable into any of the five common genotypes and, by sequence analysis, 22 were found to be of four genotypes in group 4 and one of genotype 1c in Simmond's classification.

Base Sequence↗

Negative signaling in B cells by surface immunoglobulins.

Cross-linking of surface immunoglobulins generates negative signals that cause B-cell death unless appropriate rescue signals are provided. Surface IgM is the main transducer of the negative signaling, but surface IgD and IgG may also transduce negative signaling when cross-linked intensively. In the surface IgM+, IgD+ human malignant B lymphoma cell lines B104 and DND-39, cross-linking of surface IgM by anti-IgM antibodies induced cell death. Anti-IgM antibody-induced B104 cell death was inhibited by stimulation with alpha- and beta-interferons but not stimulation with anti-CD40 antibody or IL-4, whereas anti-IgM antibody-induced DND-39 cell death was inhibited by stimulation with anti-CD40 antibody but not stimulation with alpha- and beta-interferons. Anti-IgM antibody-stimulated B104 cells had morphologic features compatible with necrosis, whereas anti-IgM antibody-stimulated DND-39 cells showed morphologic features of apoptosis. CD11a/CD54-dependent cell adhesion induced by stimulation with anti-CD40 antibody was involved in anti-CD40 antibody-mediated inhibition of anti-IgM antibody-induced DND-39 cells. In normal human mature B cells, cross-linking of surface IgM induced different signaling consequences, including DNA synthesis or cell division (positive signaling) or cell cycle arrest or death (negative signaling). In this system, too, CD40-transduced signal inhibited anti-IgM antibody-induced negative signaling, and CD11a/CD54-dependent cell adhesion played a role in the rescue process. It is suggested that quantitatively different intensities of surface IgM cross-linking induce qualitatively different signaling consequences; relatively weak cross-linking may induce DNA synthesis; moderate cross-linking may induce DNA synthesis with cell cycle arrest at the G2/M interphase; and intense cross-linking may induce apoptotic cell death. The reasons for this difference are not yet known. Further elucidation of the molecular mechanisms responsible for surface IgM-mediated negative signaling and its rescue signaling may contribute toward development of therapy for allergic disorders by artificial modulation of specific immunoglobulin production.

Animals↗

Hepatitis C virus antibody, viral RNA and genotypes in leprous patients in Japan.

BACKGROUND/METHODS: Markers of hepatitis C virus infection were tested for in 229 patients with leprosy (male 154, female 75) in Japan. RESULTS: Antibody to hepatitis C virus by a second-generation enzyme immunoassay was detected in 68 patients (30%), and RNA of hepatitis C virus in 41 (18%), in prevalence rates much higher (p < 0.001) than those in matched controls (11/923 or 1.2% and 9/923 or 1.0%, respectively). Hepatitis C virus genotypes were II/1b in 37 (90%), III/2a in three (7%) and IV/2b in one (2%), in which II/1b was more frequently (p < 0.003) represented than in hepatitis C virus carriers without leprosy in Japan (520/767 or 68%). The 41 patients with hepatitis C virus viremia had serum transaminase levels significantly higher than those in the other 188 patients without viremia (p < 0.01). CONCLUSIONS: These results indicate that leprous patients confined in institutions are at high risk of hepatitis C virus infection, and that patients infected with hepatitis C virus should be monitored for liver function and placed on interferon therapy whenever required.

Biomarkers↗

Infection with GB virus C (GBV-C) in patients with fulminant hepatitis.

BACKGROUND/METHODS: There appear to be hepatitis viruses other than hepatitis A, B, C, D and E. One of these has been proposed with a designation of GB virus C. Sera from 44 patients with fulminant hepatitis were tested for RNA of GB virus C by reverse-transcription polymerase chain reaction with nested primers deduced from the putative non-structural 3 (helicase) region. RESULTS: RNA of GB virus C was detected in three (20%) of 15 patients with hepatitis B virus infection and three (12%) of 25 patients without markers of hepatitis A-E virus infection. Overall, GB virus C RNA was detected in six (14%) of the 44 patients with fulminant hepatitis, at a frequency significantly higher (p < 0.001) than that in three (0.9%) of 326 blood donors matched for age with the patients. CONCLUSIONS: These results indicate a role of GB virus C in inducing fulminant hepatitis either by itself or in concert with the other hepatitis viruses.

Acute Disease↗

Hepatitis C virus variants from Jakarta, Indonesia classifiable into novel genotypes in the second (2e and 2f), tenth (10a) and eleventh (11a) genetic groups.

Hepatitis C virus (HCV) isolates from 126 hepatitis patients in Jakarta, Indonesia were genotyped by PCR with genotype-specific primers deduced from the HCV core gene. Fifty-five isolates (44%) were classified as genotype II/1b, 15 (12%) as 1c, 33 (26%) as III/2a, and 1 (1%) as V/3a, while the remaining 22 (17%) were not classifiable into any of the five common genotypes (I/1a, II/1b, III/2a, IV/2b and V/3a) or 1c. Sequences of a part of the NS5b region [1093 bp (nucleotides 8279-9371)] of the 22 isolates of unclassifiable genotype were subjected to pair-wise comparison and phylogenetic analysis along with those of 62 isolates of 25 genotypes in nine genetic groups. Seven of the isolates were classified into 2e and two into 2f, representing novel genotypes in genetic group 2, while ten and three were classified into two new genetic groups, 10 and 11, respectively, and their genotypes were provisionally designated 10a and 11a. The isolates of genotype 10a (JK049) and 11a (JK046) were sequenced in full. Comparison of 24 HCV genomes including those of JK049 and JK046, over the entire genome and subgenomic regions, supported the classification of HCV into 11 genetic groups.

Amino Acid Sequence↗

Genotypes and multiple infections with hepatitis C virus in patients with haemophilia A in Japan.

Hepatitis C virus (HCV) RNA was tested for, and HCV genotypes determined, in 96 patients with haemophilia A in Japan. Of 88 patients aged > or = 10 years, 74 (84%) were positive for HCV RNA at a frequency higher than that in patients aged less than 10 years (one of eight, 13%, P < 0.001). Genotype I/1a was detected in 30(40%), II/1b in 12 (16%), III/2a in eight (11%), IV/2b in five (7%) and V/3a in 12 (16%); mixed infection with HCV of two different genotypes was identified in the remaining nine (12%). This distribution was markedly different from that in 767 Japanese HCV carriers without haemophilia, in whom II/1b accounted for the majority (68.7%), I/1a was rare (0.5%), V/3a was absent, and mixed infection was observed rarely (1.3%). Mixed infection was transient in all of the seven haemophilic patients who were followed for 1 to 7 years. One of them was infected with genotype II/1b and an unclassifiable genotype, which showed nucleotide sequence similarity to genotype 4c from Zaire (82% homology in the E1 gene) and to 4a from Egypt (91% homology in a part of the NS5b region). In this patient, HCV of genotype II/1b disappeared while that of group 4 survived during a 4-year observation period. These results indicate different epidemiology of HCV genotypes in Japanese haemophiliacs, attributable to HCV contaminating factor VIII imported in the past, and an increased opportunity in haemophiliacs for mixed infection with HCV of different genotypes.

Adolescent↗

Cold activation of complement for monitoring the response to interferon in patients with chronic hepatitis C.

OBJECTIVES: Because of its specific association with hepatitis C virus (HCV) infection, the cold activation of complement is an easy and inexpensive indicator of HCV viremia. It was evaluated for eligibility as a marker of response to interferon in patients with hepatitis C. METHODS: The cold activation of complement was determined by the loss or decrease of hemolytic activity with the microtitration method in sera that had been stored at 4 degrees C overnight. RESULTS: We observed the loss of hemolytic activity by the cold activation of complement in 236 (72%) and a decrease in 56 (17%) of 327 sera from patients with HCV-associated chronic liver disease, which was much more (p < 0.001) that in 1 (1%) and 13 (14%), respectively, of 49 sera from patients with chronic liver disease associated with hepatitis B virus infection. Interferon-alpha (total dose 516 x 10(6) units) or interferon-alpha 2b (774 x 10(6) units) was given to 67 patients with chronic hepatitis C, of whom 56 had the cold activation of complement. The response to interferon was evaluated by the clearance of serum HCV RNA at 6 months after the completion of therapy. The cold activation of complement disappeared in 18 patients, of whom 15 (86%) responded. It persisted or fluctuated in the remaining 38 patients, only six (16%) of whom responded to interferon (p < 0.001). The cold activation of complement once disappeared at the completion of interferon and then reappeared in patients who relapsed after completing interferon therapy. CONCLUSIONS: These results indicate that the cold activation of complement may be associated with the presence of HCV in blood and a lower rate of durable response after completion of interferon therapy.

Adult↗

[Role of LFA-1/ICAM-1-dependent cell adhesion in CD40-mediated inhibition of anti-IgM antibody-induced B-cell death].

To investigate the role of CD40-transduced signals in surface IgM (sIgM)-mediated B cell death, we used a human B cell line (DND-39). Crosslinking of sIgM by Abs induced DND-39 cell death (apoptosis). Anti-CD40 Abs induced homotypic adhesion of DND-39 cells and rescued them from anti-IgM Ab-induced apoptosis. Treatment with Abs against LFA-1/ICAM-1 inhibited not only the homotypic adhesion but also the inhibition of anti-IgM Ab-induced apoptosis by anti-CD40 Ab. Otherwise, CD11a antisense decreased the inhibitory effect of anti-CD40 Ab on anti-IgM Ab-induced apoptosis. The data show that LFA-1/ICAM-1-dependent cell adhesion induced by signaling through CD40 plays an important role in the inhibition of anti-IgM Ab-induced apoptosis of DND-39 cells.

Animals↗

[Clinical reliability of a new IgE detection system using chemiluminescent enzyme immunoassay named LUMIWARD immunoassay system].

The measurement of allergen-specific IgE antibodies and total IgE was performed with LUMIWARD immunoassay system (chemiluminescent enzyme immunoassay) using 406 serum samples obtained from patients with various allergic diseases and 81 serum samples from normal donors. These were collected by departments of internal medicine, pediatrics, dermatology and otorynolaryngology at eleven institutes in Japan. In addition to a comparative study with CAP RAST, skin tests were also performed to establish a clinical diagnosis. Simultaneous measurements were performed and an excellent correlation with CAP RAST was observed with a concordance rate of 92.6% and correlation coefficient of 0.922. The specificity determined by the normal serum samples was 96.4% for CAP RAST and 96.2% for LUMIWARD. The sensitivity determined by the samples, of which etiological allergens were identified clinically, was 84.8% for CAP RAST and 85.5% for LUMIWARD. Among them, the sensitivity of skin test was 91.8%. The concordance rate with clinical diagnosis was as high as 90.6% and 90.8% for CAP RAST and LUMIWARD. The normal upper limit of total IgE by cumulative 95% value was calculated to be 170 IU/ml for adult subjects. These results indicate the clinical usefulness of the LUMIWARD immunoassay system in evaluating IgE antibodies and total IgE.

Adult↗

Core promoter mutations of hepatitis B virus for the response to interferon in e antigen-positive chronic hepatitis B.

OBJECTIVES: Mutations in the precore region are not always detected in hepatitis B virus (HBV) from patients with chronic hepatitis B who respond to interferon and lose hepatitis B e antigen (HBeAg) from serum. The other mutations may also be responsible for the loss of HBeAg and response. METHODS: Forty six consecutive patients with HBeAg-positive chronic hepatitis B received recombinant-alpha 2 a interferon (total dose: 702 MU). The mutation for stop codon 28 in the precore region was determined by restriction fragment length polymorphism, and mutations in the core promoter were searched for in five HBV DNA clones propagated from each patient. RESULTS: HBeAg was cleared at 6 months after interferon in 11 (61%) of 18 patients with the precore mutation and in 12 (43%) of 28 without it. Of these 28 patients, 19 with mutations in the core promoter in all five HBV DNA clones lost HBeAg more frequently than the remaining nine who had at least one clone among the five that lacked such mutations (58 vs 11%, p < 0.05). CONCLUSIONS: HBeAg-positive patients infected with HBV variants having mutations for an HBeAg-negative phenotype would respond better to interferon by clearing HBeAg from serum. Such mutations may not necessarily be in the precore region but also in the core promoter, which would interfere with the synthesis and secretion of HBeAg either at the translation or transcription level.

Adult↗

Prostaglandin E2 at priming of naive CD4+ T cells inhibits acquisition of ability to produce IFN-gamma and IL-2, but not IL-4 and IL-5.

We investigated the effect of prostaglandin E2 on the acquisition of cytokine-producing ability by naive CD4+ T cells in human cord blood. Naive CD4+ T cells were stimulated for 3 days with mouse monoclonal anti-CD3 Ab, then washed and expanded in IL-2-containing medium for 3 more days. These activated T cells produced IL-2, IL-4, IL-5, and IFN-gamma upon stimulation with PMA and ionomycin. PGE2 added at priming of naive T cells inhibited the production of IL-2 and IFN-gamma, but not of IL-4 and IL-5, in a dose-dependent manner. This change in the cytokine production profile induced by PGE2 was maintained in T cells restimulated with anti-CD3 in the absence of PGE2, expanded by IL-2, and stimulated with PMA and ionomycin. The mRNA expression of IFN-gamma and IL-2, but not that of IL-4, was also decreased in these cells. Forskolin and dibutyryl cAMP had a similar effect. PGE2 must exist at an early stage of T cell activation to inhibit priming for IL-2 and IFN-gamma production. PGE2 also showed this effect, even in the presence of exogenous IFN-gamma, at the primary stimulation. These results indicate that PGE2 inhibits the acquisition of the ability to produce IL-2 and IFN-gamma by acting directly on naive T cells. Our results suggest that PGE2 plays a role in facilitating the development of the Th2-type cytokine production profile.

Animals↗

Pyrrolidine dithiocarbamate inhibits intercellular adhesion molecule-1 biosynthesis induced by cytokines in human fibroblasts.

Intercellular adhesion molecule-1 (ICAM-1), the ligand of lymphocyte function-associated antigen-1, plays an important role in the interactions of a variety of hemopoietic and nonhemopoietic cells, including leukocytes, fibroblasts, and endothelial cells. ICAM-1 is known to be involved in the onset of several diseases such as inflammation, allograft rejection, and so on. In this report, we investigated the effects of dexamethasone, cyclosporin A, FK506, and pyrrolidine dithiocarbamate (PDTC) on the induction of the ICAM-1 gene by cytokines in fibroblasts. PDTC, a potent inhibitor of NF-kappa B, was shown by ELISA and FACS analysis to prevent dramatically the expression of the ICAM-1 gene stimulated by IL-1 alpha, IFN-gamma, and PMA, although the other reagents inhibited it only slightly. Ribonuclease protection assay revealed that PDTC blocked the expression of the ICAM-1 gene at the mRNA level. To elucidate the mechanism of this inhibition, we constructed a series of ICAM-1 promoter deletion mutants linked to the chloramphenicol acetyl transferase gene and analyzed the effect of PDTC on their activities. Transient transfection analysis indicated that the critical region for inhibition by PDTC is an NF-kappa B binding site-like motif (GGGAGGATTCC, ICAM-1 kappa B) that is located at position-540. Electrophoresis mobility shift assay revealed that PDTC actually inhibits the binding of NF-kappa B (or NF-kappa B-like) protein to the ICAM-1 kappa B site. These findings suggest that PDTC inhibits ICAM-1 gene expression by inhibiting the association of NF-kappa B (or NF-kappa B-like) protein with the ICAM-1 kappa B site.

Base Sequence↗