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Biomedical subjects

M Mizokami

Publications and source records attributed to M Mizokami.

At least 91 records · Page 5Linked to original sources
PubMed1997

Variations of hepatitis B virus core gene sequence in Western patients with chronic hepatitis B virus infection.

Heterogeneity of the hepatitis B virus (HBV) core gene has been reported to be associated with the presence of active liver disease in Japanese patients with chronic HBV infection. This study evaluated the significance of HBV core gene heterogeneity in Western patients with chronic HBV infection. The hepatitis B virus precore/core gene from 45 patients (inactive:active liver disease ratio 16:29) was amplified from serum by polymerase chain reaction (PCR). Gel electrophoresis was employed to detect large deletions. The PCR amplicons from 13 patients (all HBV serotype adw but with a different spectrum of liver disease) were cloned and sequenced. Hepatitis B surface antigen (HBsAg) serotypes were tested by enzyme immunoassay (EIA) and hepatic expression of HBV antigens was assessed by immunohistochemistry. The HBV core gene was amplified from the serum of all 45 patients. Three patients had mixed infection with both precore mutant and wild-type HBV and all three had active liver disease. No patient had a large deletion of the HBV core gene. Hepatitis B virus core gene sequence variations were more common in the midcore region and there was no difference in the number of silent and missense substitutions between those with inactive and active liver disease. There was no correlation between the nucleotide or encoded amino acid substitutions and the clinical and biochemical parameters, including the subsequent response to interferon-alpha therapy (n = 37) or hepatic HBV antigen expression. Variation of the HBV core gene was not found to be preferentially associated with active liver disease in Western patients with chronic HBV infection. The pattern of hepatitis B core gene variation is in accord with the genomic organization of HBV.

Adult↗
PubMed1997

Cell density and antioxidant vitamins determine the effects of hyperoxia on proliferation and death of MDCK epithelial cells.

Epithelial cells are prone to oxidant injury, which could change epithelial cell homeostasis and lead to degenerative diseases. We examined the effects of hyperoxia on death and proliferation off Madin-Darby canine kidney (MDCK) epithelial cells and antioxidant vitamin protection. Subconfluent and near-confluent MDCK cells were cultured under normoxia or hyperoxia for two days. We measured cell number and viability, mitochondria enzymatic activity, thymidine incorporation, necrosis [lactate dehydrogenase (LDH) release], and apoptosis (DNA fragmentation and morphological changes). When the cells were subconfluent, hyperoxia decreased the number of adherent cells, mitochondrial enzymatic activity, and thymidine incorporation, but neither LDH release nor apoptotic changes increased compared with normoxic controls. In normoxia, near-confluent cells had lower nonadherent cell numbers, mitochondrial enzymatic activity, and thymidine incorporation than subconfluent cells; hyperoxia further decreased the latter two parameters and increased apoptotic changes and LDH release in near-confluent cells. Vitamin E protected mitochondrial enzymatic activity, apoptotic changes, and LDH release against hyperoxic injury but did not affect changes in thymidine incorporation with hyperoxia. Vitamin C partially protected the mitochondrial enzymatic activity and thymidine incorporation in subconfluence, but not in near confluence. These results indicate that cell density is a major determinant of the effects of hyperoxic injury and the profile of antioxidant vitamin protection.

Animals↗
PubMed1997

Effect of interferon-alpha and ribavirin therapy on serum GB virus C/hepatitis G virus (GBV-C/HGV) RNA levels in patients chronically infected with hepatitis C virus and GBV-C/HGV.

GB virus C/hepatitis G virus (GBV-C/HGV) is a newly described virus associated with hepatitis in humans, and GBV-C/HGV coinfection is common in patients chronically infected with hepatitis C virus (HCV). To determine the clinical impact of GBV-C/HGV infection in such patients and the effect of interferon-alpha and ribavirin therapy on serum GBV-C/HGV RNA levels, GBV-C/HGV RNA was detected and quantitated in serum samples from 62 chronically infected HCV patients by a combination of a qualitative nested reverse transcription-polymerase chain reaction and a newly developed quantitative branched DNA assay: 10 patients were positive for serum GBV-C/HGV RNA. There were no differences in the clinical, biochemical, and histologic features of the patients with GBV-C/HGV-HCV coinfection compared with those with HCV infection alone. Interferon-alpha treatment caused a marked but usually transient reduction in serum GBV-C/HGV RNA, and ribavirin had, at most, a modest antiviral effect.

Adult↗
PubMed1997

Early therapy with interferon for acute hepatitis C acquired through a needlestick.

Because there is no effective neutralizing antibody or vaccine for preventing hepatitis C virus (HCV) transmission, HCV can be transmitted to health care workers through accidental needlesticks. Recently, two of our health care workers acquired HCV infection through needlestick accidents and developed acute hepatitis C. The route of transmission was confirmed by molecular evolutionary analysis with use of the E2 region of the HCV genome. After the clinical onset of acute hepatitis, the health care workers were treated with interferon (IFN) (total dose, approximately 300 megaunits). Neither individual developed chronic hepatitis. This finding raises the possibility that treatment with low-dose IFN following an accidental needlestick may be beneficial, even when it is started after the clinical onset of hepatitis.

Acute Disease↗
PubMed1997

GB virus C/hepatitis G virus infection in southern China.

The prevalence of GB virus C/hepatitis G virus (GBV-C/HGV) infection among intravenous drug users (IVDUs), patients with liver diseases, and blood donors in Nanning, southern China was studied. GBV-C/HGV RNA was detected by reverse transcription polymerase chain reaction with primers derived from the 5'-untranslated region. GBV-C/HGV RNA was detected in 64 of 85 IVDUs, 20 of 80 persons with liver disease, and 1 of 50 blood donors. Among IVDUs, GBV-C/HGV infection was associated with antibodies to hepatis C virus (HCV) and with hepatitis B surface antigen (HBsAg). Eleven nucleotide sequences were determined and analyzed by molecular evolutionary analysis. In a phylogenetic tree, the isolates were grouped in three clusters with GBV-C and HGV grouped in two clusters. These data indicate that GBV-C/HGV infection is common in China among IVDUs but uncommon among persons with liver disease without HBsAg or anti-HCV and that there is a new group of GBV-C/HGV.

Blood Donors↗
PubMed1997

Interferon-alpha therapy for individuals with normal serum alanine aminotransferase levels before treatment.

While interferon (IFN) therapy is approved for patients with chronic hepatitis C infection, the effectiveness of IFN therapy for anti-hepatitis C virus (HCV)-positive individuals with normal ALT levels remains poorly understood. Twenty-five individuals (M:F = 9:16; age = 51.8 +/- 15.1 years) who showed a normal alanine aminotransferase (ALT) level (< 30 IU/L) at least 6 months before treatment and were positive for both anti-HCV and serum HCV-RNA by reverse transcription polymerase chain reaction (RT-PCR) were studied. Of these, 16 received IFN therapy for 24 weeks (780 million units total IFN-alpha 2b) and nine were followed for 12 months as controls. The serum HCV-RNA level was determined by bDNA assay and HCV genotype was detected by enzyme immunoassay. All were shown to have chronic hepatitis by liver biopsy. Six (37.5%) of 16 individuals lost serum HCV-RNA by RT-PCR 6 months after cessation of therapy (complete response; CR), while the remaining individuals were defined as non-responders (NR). Of the six individuals in the CR group, five had HCV type 2 infection, compared with none of 10 individuals in the NR group (P < 0.01). There was a trend towards a lower pretreatment viraemia level in the CR group than in the NR group. These data suggest that IFN therapy for individuals with HCV type 2 infection and normal ALT levels was effective.

Alanine Transaminase↗
PubMed1997

GB virus infection in patients with oral cancer and oral lichen planus.

We studied the incidence of GBV-C infection in patients with oral cancer or oral lichen planus (OLP). Subjects included 38 patients with oral cancer and 34 patients with OLP from whom serum was collected to detect GBV-C-RNA using reverse transcription (RT) "nested" PCR. GBV-C-RNA was positive in 1 (2.6%) oral cancer patient and 3 (8.8%) OLP patients. All 4 GBV-C-positive patients were also positive both for the antibody for hepatitis C virus (anti-HCV) and HCV-RNA, indicating simultaneous infection with GBV-C and HCV. In conclusion, GBV-C infection was found in 5.5% (4/72) of oral cancer or OLP patients and all patients infected with GBV-C also had HCV infection. This suggests that GBV-C infection is unlikely to play an important role in the pathogenesis of oral cancer and OLP.

Aged↗
PubMed1997

New hepatitis C virus (HCV) genotyping system that allows for identification of HCV genotypes 1a, 1b, 2a, 2b, 3a, 3b, 4, 5a, and 6a.

Recent studies have focused on whether different hepatitis C virus (HCV) genotypes are associated with different profiles of pathogenicity, infectivity, and response to antiviral therapy. The establishment of a simple and precise genotyping system for HCV is essential to address these issues. A new genotyping system based on PCR of the core region with genotype-specific PCR primers for the determination of HCV genotypes 1a, 1b, 2a, 2b, 3a, 3b, 4, 5a, and 6a was developed. A total of 607 samples (379 from Japan, 63 from the United States, 53 from Korea, 35 from Taiwan, 32 from China, 20 from Hong Kong, 15 from Australia, 6 from Egypt, 3 from Bangladesh, and 1 from South Africa) were tested by both the assay of Okamoto et al. (H. Okamoto, Y. Sugiyama, S. Okada, K. Kurai, Y. Akahane, Y. Sugai, T. Tanaka, K. Sato, F. Tsuda, Y. Miyamura, and M. Mayumi, J. Gen. Virol. 73:673-679, 1992) and this new genotyping system. Comparison of the results showed concordant results for 539 samples (88.8%). Of the 68 samples with discordant results, the nucleotide sequences of the HCV isolates were determined in 23, and their genotypes were determined by molecular evolutionary analysis. In all 23 samples, the assignment of genotype by our new genotyping system was correct. This genotyping system may be useful for large-scale determination of HCV genotypes in clinical studies.

DNA Primers↗
PubMed1997

Routes of transmission of hepatitis C virus in an endemic rural area of Japan. Molecular epidemiologic study of hepatitis C virus infection.

We conducted an epidemiological study to investigate the routes of transmission of hepatitis C virus (HCV) infection in an area endemic for HCV. Subjects were the 857 adult inhabitants of K area, Japan. The prevalence of antibody to HCV (anti-HCV) was 26.3%. The HCV genotype 1b was the most prevalent (89.3%) among the anti-HCV positive subjects. Molecular evolutionary analysis, based on the nucleotide sequences of the HCV core region from 23 participants with type 1b, showed that the isolates were distributed into more than 1 group. Multivariate regression analysis demonstrated that an age over 40 years, a history of blood transfusion, the presence of antibody to hepatitis B core antigen (anti-HBc), or a history of surgery were each independently associated with the presence of anti-HCV. No significant differences in the presence of anti-HCV prevalence were observed between the wives of men positive for anti-HCV (33.3%) and age-matched women (36.4%), or between the husbands of women positive for anti-HCV (36.4%) and age-matched men (38.3%), from the same area. Findings suggest that the various strains of HCV type 1b were transmitted via medical procedures, not by the intrafamilial route.

Adult↗
PubMed1997

[Molecular evolutionary analysis of GB viruses and hepatitis G virus].

Recently, new blood-transfusion transmissible viruses, called hepatitis G virus(HGV) and GB virus-C(GBV-C), have been reported. It was found that two viruses were independent isolates of the same virus, the genomic structure resembled that of flavivirus family, and GBV-C/HGV was closely related to HCV. To elucidate the evolutionary relationship between hepatitis C virus(HCV) and GBV-C/HGV, we constructed the phylogenetic trees for the putative RNA helicase and the RNA-dependent RNA polymerase regions of the Flaviviridae by UPGMA. The tree showed that HCV was closely related to GB virus-B(GBV-B) and HGV was more nearer to GB virus-A(GBV-A) rather than HCV.

Amino Acid Sequence↗
PubMed1997

Prevalence and molecular epidemiology of GB virus C/hepatitis G virus infection in Mongolia.

We studied the prevalence of GB virus C/hepatitis G virus (GBV-C/HGV) infection among 112 patients with liver disease and 121 blood donors in Ulaanbaatar, Mongolia. Reverse transcription and polymerase chain reaction were employed to detect GBV-C/HGV RNA using the specific primers derived from the 5'-untranslated region (5'-UTR) of the GBV-C/HGV genome. Nucleotide sequences of all positive samples for GBV-C/HGV RNA were determined. The sequences were analyzed by a molecular evolutionary method. Twenty-five (10.7%) of 233 people were positive for GBV-C/HGV RNA. Eight (6.6%), 11 (9.1%), and 30 (24.8%) blood donors were positive for GBV-C/HGV RNA, HBsAg, and anti-HCV, respectively, although 17 (15.2%), 65 (58.0%), and 64 (54.5%) patients with liver disease were positive for each viral marker. The prevalences of GBV-C/HGV RNA, HBV, and HCV in the patients were significantly higher than those in blood donors (P < 0.05). There was no significant difference in the prevalence of anti-HCV among people with and without GBV-C/HGV RNA, while the prevalence of HBsAg among people with GBV-C/HGV RNA was significantly higher than among those without GBV-C/HGV RNA (P < 0.05). The molecular evolutionary tree showed that GBV-C/HGV was a heterogeneous virus and all strains could be divided into 2 types. One is the same phylogenetic type as HGV, and the other is a new type that is different from GBV-C and HGV.

Adult↗
PubMed1996

Distribution of hepatitis C virus genotypes determined by line probe assay in patients with chronic hepatitis C seen at tertiary referral centers in the United States. Hepatitis Interventional Therapy Group.

OBJECTIVE: To 1) verify the validity of a new line probe assay for hepatitis C virus (HCV) genotyping and 2) determine the distribution of HCV genotypes and the association between HCV genotype and clinical variables in patients with chronic hepatitis C seen in tertiary referral centers in the United States. DESIGN: Retrospective cross-sectional analysis. PATIENTS: 438 patients with chronic hepatitis C from 10 tertiary referral centers. MEASUREMENTS: The validity of the line probe assay was first verified against a panel of serum specimens that had previously been characterized by six different HCV genotyping methods. Specimens from all 438 patients were then genotyped using this line probe assay. The associations between HCV genotype and clinical variables were examined using analysis of variance. Pairwise testing was used when the F test showed a statistically significant difference. Nonparametric alternatives were used for variables for which normality could not be assumed. RESULTS: The line probe assay was quick and reproducible, and it showed good concordance with other tests. In our sample, the proportions of patients with HCV types 1, 2, 3, and 4 were 71.5%, 13.5%, 5.5%, and 1.1%, respectively. Subtypes 1a and 1b were seen in approximately equal proportions of patients with HCV type 1. Mixed infection was detected in 3.7% of specimens, and 4.8% of specimens either had negative results on polymerase chain reaction or could not be typed. A higher proportion of patients with HCV type 1 than of patients with HCV-type 1 had acquired HCV through transfusion of blood products (50% compared with 25%; P < 0.001). Patients with HCV type 1 also had a longer estimated duration of infection compared with patients with HCV type 3 (P = 0.004) and type 4 (P = 0.049). Disease activity did not differ among patients infected with HCV types 1, 2, or 3. Levels of viremia were similar in patients with HCV types 1, 2, or 3, but patients with HCV type 4 had a lower level of viremia than did patients with HCV type 1 (P = 0.047). CONCLUSIONS: The line probe assay can be used in patients with chronic HCV infection in the United States. In patients with chronic hepatitis C referred to tertiary centers in the United States, type 1 is the most common HCV genotype. Disease activity and viremia levels do not differ among patients chronically infected with HCV types 1, 2, or 3.

Adolescent↗
PubMed1996

Serologically defined genotypes of hepatitis C virus among Japanese patients with chronic hepatitis C.

Recently, Tsukiyama-Kohara et al. (1993) reported that most hepatitis C viruses (HCVs) in Japan can be classified into two types, type 1 and type 2, on the basis of the NS4 region nucleotide sequence. They developed a new assay in which antibodies against group-specific recombinant proteins of the NS4 region were measured by ELISA (serologically defined genotype, serotype). In the present study, we examined 306 patients with chronic liver disease due to HCV infection. The sensitivity of this assay was 98.7% (302/306). The serotype distribution of HCV was 230/306 (75.2%) for type 1, 65/306 (21.2%) for type 2, 7/306 (2.3%) for mixed, both being positive, and 4/306 (1.3%) indeterminate. The frequency of type 1 was significantly higher than that of type 2 (P < 0.01). There were no significant differences in clinical characteristics among the mixed and the indeterminate serotypes. Among the mixed-serotype patients, 4/7 (57.1%) showed seroconversion to a single serotype at 6 and 9 months later, although the serotypes of the indeterminate-serotype patients were also indeterminate at 6 and 9 months later. Using aliquots of the same serum samples, HCV genotyping was carried out by the reverse transcription polymerase chain reaction (RT-PCR) method using type-specific primers derived from the NS5 region of HCV to verify the specificity of this serotyping. The sensitivity of genotyping by RT-PCR was 167/183 (91.3%). The HCV genotypes determined by both methods were consistent in 161/183 (88.0%) of the cases, and there were no contradictory results for any sample between the two methods. These findings indicate that serological genotyping might be useful in determining the HCV genotype among Japanese patients with HCV infection.

Carcinoma, Hepatocellular↗
PubMed1996

Evolutionary relationship of hepatitis C, pesti-, flavi-, plantviruses, and newly discovered GB hepatitis agents.

Two flavivirus-like viruses, GB virus-A (GBV-A) and GB virus-B (GBV-B), were recently identified in the GB hepatitis agent, and are distinct from the hepatitis A to E viruses. The putative helicase domain of GBV-A and GBV-B was found to have amino acid sequence homology with hepatitis C virus (HCV), and distantly, is also related to pestiviruses, flaviviruses, and plant viruses. A phylogenetic tree construction showed that GBVs and HCV are closely related, and they are clustered with pestiviruses, flaviviruses and plant viruses in that order.

Amino Acid Sequence↗
PubMed1996

Comparison of serum hepatitis C virus RNA concentration by branched DNA probe assay with competitive reverse transcription polymerase chain reaction as a predictor of response to interferon-alpha therapy in chronic hepatitis C patients.

A study was carried out to assess the correlation between the serum concentration of hepatitis C virus RNA (HCV-RNA) in patients with chronic hepatitis, as measured by competitive reverse transcription polymerase chain reaction (cRT-PCR) and branched DNA probe assay (bDNA), and response to interferon-alpha (IFN alpha) therapy. The serum HCV-RNA concentration was evaluated by both cRT-PCR and bDNA in 54 patients who had received a total dose of 480 MU of IFN alpha. HCV subtypes were also identified in all patients. The measurement of serum HCV-RNA concentration by bDNA correlated significantly with that of cRT-PCR. The concentration of HCV-RNA in subtype 1 patients was significantly higher than that in subtype 2 patients when measured by bDNA, but not when measured by cRT-PCR. The correlation of HCV-RNA concentration between bDNA and cRT-PCR was associated with both subtypes 1 and 2. The difference in serum HCV-RNA concentration between complete and incomplete responders was more significant when measured by bDNA probe assay than by cRT-PCR. Moreover, only 1 of 26 patients with a HCV-RNA concentration of more than 1 x 10(6) eq/ml as measured by bDNA probe assay attained a complete response, while 19 of 28 patients with that of less than 1 x 10(6) eq/ml achieved it. Measurement of serum HCV-RNA concentration by bDNA probe assay was a better predictor of clinical response of IFN alpha therapy than measurement by cRT-PCR.

Adult↗
PubMed1996

Clinical implications of viral quasispecies heterogeneity in chronic hepatitis C.

To determine the clinical significance of viral quasispecies heterogeneity, 59 patients with chronic hepatitis C were studied using singlestranded conformational polymorphism (SSCP) analysis of the HCV E2 hypervariable region 1 (HVR1); of these, 48 were subsequently treated with interferon-alpha. The SSCP method was validated using clones of known nucleotide sequence. HVR1 was amplified in 54 of 59 (92%) patients. The median number of SSCP bands per sample was 6 (range: 2-12). Increased quasispecies heterogeneity correlated with the estimated duration of HCV infection (P < 0.05), parenteral-acquired HCV infection (vs. sporadic, P < 0.05), serum HCV RNA levels (P < 0.05), and HCV genotype 1 infection (P < 0.05), but not with age, serum AST, ALT, or Knodell score. Patients who had complete and sustained response to interferon-alpha (n = 11) had lower pre-treatment quasispecies heterogeneity compared to patients who had complete response with relapse (n = 18, P < 0.05) or no complete response (n = 16, P < 0.01). However, multivariate analysis revealed that HCV viremia was a stronger predictor of response to interferon-alpha. These findings indicate that the estimated duration of HCV carriage, serum HCV RNA levels, and HCV type 1 are important determinants for the evolution of HCV quasispecies heterogeneity; and that increased HCV quasispecies heterogeneity is another marker associated with a poor subsequent response to interferon-alpha.

Adult↗