Kazumasa Watanabe

Long term effects of phlebotomy on biochemical and histological parameters of chronic hepatitis C

OBJECTIVE:There is considerable evidence that iron is a risk factor for liver injury in chronic hepatitis C. Known as iron reduction therapy, phlebotomy reduces serum ALT activity. This effect might continue with maintenance phlebotomy and result in slower progression of liver fibrosis.METHODS:We examined the biochemical parameters and liver histology of patients with chronic hepatitis C treated by maintenance phlebotomy. For biochemical evaluation, 25 patients were treated by initial phlebotomy to reduce serum ferritin levels to 10 ng/ml or less and then observed for 5 yr with maintenance phlebotomy to maintain the iron-deficient state. For histological evaluation, liver biopsies were performed before and after the study period in 13 of the patients. Thirteen patients who were virological nonresponders to interferon alone and had undergone second liver biopsies after more than 3 yr served as histological controls.RESULTS:Serum aminotransferase levels were decreased significantly by initial phlebotomy and remained at the same levels during the study period (p < 0.05). The grading scores were improved significantly in the study group (p < 0.05) and unchanged in the controls. The staging scores remained unchanged in the study group but were increased in the controls (p < 0.005). Disease progression was significantly different between the two groups (p < 0.05).CONCLUSIONS:These results suggest that phlebotomy with maintenance lowers serum aminotransferase levels, improves liver inflammation, and suppresses the progression of liver fibrosis in chronic hepatitis C.

TT virus infection in hemodialysis patients

OBJECTIVE:Recently, TT virus (TTV), associated with posttransfusion hepatitis, was discovered. Prevalence of TTV infection in maintenance hemodialysis (HD) units and its pathogenicity to liver was investigated.METHODS:A total of 115 patients on HD were assessed for presence of serum TTV. DNA was purified from sera, and nested polymerase chain reaction was done for the detection of TTV DNA.RESULTS:TTV was detected in 59 patients on HD (51.3%), as compared with healthy blood donors (15 of 91 [16.5%], p < 0.0001). Serum HCV RNA and HBs antigen were positive in 16 and three patients, respectively. The prevalence rate of TTV was already 58.3% in the patients on HD for only 1 yr, and did not change according to the duration of HD until 15 yr on HD. TTV was positive in 51.2% (43 of 84) of the patients with history of blood transfusion, and in 51.6% (16 of 31) of those without it. In HCV-negative patients, alanine aminotransferase (ALT) levels of TTV-positive patients were similar to those of TTV-negative patients. Contrarily, in HCV-positive patients, ALT levels were more frequently ≥15 IU/L in TTV-positive patients (14 of 18) than in TTV-negative patients (five of 15) (p < 0.05).CONCLUSIONS:TTV infection is remarkably prevalent in patients on HD and in healthy blood donors. It is suggested that TTV generally does not cause liver disease by itself, but there remains the possibility that TTV may aggravate liver disease caused by HCV.

Amino acid substitutions in the nonstructural region 5A of hepatitis C virus genotypes 2a and 2b and its relation to viral load and response to interferon

OBJECTIVES:The interferon sensitivity-determining region (ISDR) in nonstructural region 5A (NS5A) of hepatitis C virus genotype 1b has been reported to correlate with response to interferon therapy and viral load. Recently the correlation between NS5A and response to interferon in genotype 2a was also reported. We examined the region of genotypes 2a and 2b corresponding to the ISDR of genotype 1b to elucidate its correlation with response to interferon and viral load.METHODS:The sequences of amino acid positions 2213–2248 in NS5A were determined in 39 patients with genotype 2a and 12 patients with genotype 2b.RESULTS:In the patients infected with genotype 2a, the number of amino acid substitutions in the ISDR-corresponding region compared with the consensus sequence of genotype 2a was significantly correlated with viral load (ρ= − 0.541, p < 0.001) and with response to interferon therapy (p < 0.05); 83% of the patients with three or more substitutions obtained sustained responses, whereas only 44% of those with less than three substitutions obtained sustained responses. Multivariate analysis confirmed that the number of substitutions in the ISDR-corresponding region of genotype 2a was one of the independent predictors of response to interferon therapy (discriminant coefficient = 1.35, p < 0.001).CONCLUSIONS:Substitutions in the ISDR-corresponding region in NS5A of hepatitis C virus genotype 2a was confirmed to correlate to viral load and response to interferon therapy. In genotype 2b, further work must be considered because of the small number of patients studied.

Biochemical response to interferon therapy correlates with interferon sensitivity-determining region in hepatitis C virus genotype 1b infection.

Biochemical responders maintain normal alanine aminotransferase levels after interferon (IFN) therapy despite persistent presence of hepatitis C virus (HCV) RNA in their sera. There have been few reports on predictive factors for biochemical response. A region associated with sensitivity to IFN was identified in the nonstructural protein 5 A of genotype 1b [aa 2209–2248; IFN sensitivity‐determining region (ISDR)]. The substitutions in ISDR correlate with sustained response to IFN. In this report, we assessed the association of ISDR with biochemical response. The sequences of ISDR were determined in 62 patients with HCV genotype 1b treated by IFN in two randomized controlled trials. 30 patients had wild ISDR (identical to HCV‐J), 20 intermediate ISDR (1–3 amino acid substitutions compared with HCV‐J), and 12 mutant ISDR (four or more amino acid substitutions). All 12 patients with mutant ISDR had a sustained response, while only one of those with wild or intermediate ISDR had a sustained response (P < 0.0001). In the 49 patients other than sustained responders, the patients with intermediate ISDR obtained biochemical response significantly more frequently (52.6%, 10/19) than those with wild‐type ISDR (20.0%, 6/30) (P < 0.05). Multivariate analysis indicated the number of substitutions in ISDR as the most important predictor for biochemical response (discriminant coefficient=1.08, P < 0.05) and sustained response (discriminant coefficient=6.13, P < 0.0001). In phylogenetic analysis, clustering of sustained responders and biochemical responders was observed. These results demonstrate that the substitutions in ISDR are the most important predictor for biochemical response to IFN in patients infected with genotype 1b as well as for sustained response.

Interferon sensitivity‐determining region of nonstructural region 5A of hepatitis C virus genotype 1b correlates with serum alanine aminotransferase levels in chronic infection

Summary.  The mutations in the interferon (IFN) sensitivity‐determining region (ISDR) of nonstructural region 5A (NS5A) of hepatitis C virus (HCV) have been correlated with response to IFN therapy. NS5A appears to disrupt a host antiviral pathway that plays a role in suppressing virus replication and protects hepatocytes from apoptosis. We assessed whether ISDR correlates with viral load and serum alanine aminotransferase (ALT) levels. Serum viral load and ALT levels were prospectively measured bimonthly by HCV core protein assay and monthly, respectively, for 22 months in 87 patients chronically infected with HCV genotype 1b. ISDR of HCV was directly sequenced from the products of reverse transcription and polymerase chain reaction of HCV RNA. Five patients had four or more substitutions (mutant type), 33 had 1–3 (intermediate type), and 49 had no substitutions (wild type) in ISDR. The numbers of substitutions in ISDR were inversely correlated with mean viral load over a 22‐month period (r = 0.292, P = 0.0060) and directly with mean serum ALT levels (r = 0.360, P = 0.0006). The numbers of substitutions in ISDR was significantly larger in the patients with changes of viral load more than fivefold during the 22 months (1.4 ± 2.4) than in those without changes (0.6 ± 0.8) (P = 0.0188). The present study demonstrates that the patients with more substitutions in ISDR had significantly higher serum ALT levels and smaller viral load. These results suggest that NS5A with more substitutions in ISDR may lose the ability to block host antiviral pathways and to protect hepatocytes from apoptosis.

Real-time detection system for quantitation of hepatitis C virus RNA: a comparison with the other three methods.

Real-time detection (RTD) system for quantitation of hepatitis C virus (HCV) was developed. Its sensitivity and usefulness were compared with the other three commercially available methods for quantitation of HCV. The sera of 166 patients positive for serum HCV RNA by Amplicor HCV test were assessed. HCV was detected in 78.5% (128/163) by branched DNA assay, in 88.8% (111/125) by HCV core protein assay, in 94.5% (156/165) by Amplicor HCV Monitor test, and in 97.0% (161/166) by the RTD system. The values of viral load by the RTD system were significantly well correlated with those obtained by the other three methods. In the 50 patients treated by interferons (IFNs), the range which predicts the highest sustained response rate was less than 0.5 Meq/ml for branched DNA assay (sustained response rate: 57.9% (11/19)), less than 1 kcopies/ml for Amplicor HCV Monitor test (85.7% (6/7)), and less than 10(4) copies/ml for RTD system (100% (7/7)). None of the patients with greater than or equal to 2.8 Meq/ml by branched DNA assay (n=14), greater than or equal to 250 kcopies/ml by Amplicor HCV Monitor test (n=19), or greater than or equal to 2x10(6) copies/ml by RTD system (n=16) obtained sustained response. In conclusion, RTD system was demonstrated to be the most sensitive method for quantitation of HCV, and useful for the prediction of sustained response to IFN therapy.

Effects of diffusion on geminate charge recombination

Abstract Diffusion effects on geminate charge recombination are investigated for intermolecular electron transfer system. Analytical and numerical calculations are presented for reaction-diffusion equations. In some limiting cases of the equations, a condition is established where the population of geminate ion pairs decreases exponentially by charge recombination. This condition is that the ion pairs are produced inside the zone of recombination and charge recombination takes place before ion pairs diffuse into separated ions. Numerical calculations are made in realistic cases where reorganization energy in the expression of the rate constant depends on the reactant distance. As a result, we found that the population of ion pairs has both components of exponential decrease and a root inverse tail ( t −1/2 ). The component of exponential decrease is large when the recombination rate is fast.

Mutations in interferon sensitivity-determining region of hepatitis C virus: its relation to change in viral load

OBJECTIVE:Interferon sensitivity-determining region (ISDR) in nonstructural region 5A of hepatitis C virus (HCV) genotype-1b has been reported to be associated with viral load. Viral load is usually small in the patients with mutant type (four or more amino acid substitutions, compared with HCV-J) and large in those with wild (identical to HCV-J) or intermediate type (from one to three amino acid substitutions). A possible correlation was investigated between mutations in ISDR and alterations of viral load during the course of disease.METHODS:The sequences of ISDR were determined in eight patients with significant changes of viral load and in 11 patients without changes.RESULTS:In two of the eight patients with significant alterations of viral load, ISDR sequences changed significantly. In one patient whose viral load increased after a course of interferon therapy, the number of substitutions, compared with HCV-J, decreased from five to zero or one; the type of ISDR converted from mutant type to wild or intermediate type. In one patient whose viral load decreased significantly after two courses of interferon therapy, the number of substitutions increased from one to six; ISDR changed from intermediate type to mutant type. In the remaining six patients with changes of viral load and in the other 11 patients without changes, the sequences of ISDR did not change significantly.CONCLUSIONS:The mutations in ISDR are one of the viral factors involved in the changes in viral load during the course of disease, although the majority of other factors involved are still unknown.

Original contributionAmino acid substitutions in the nonstructural region 5A of hepatitis C virus genotypes 2a and 2b and its relation to viral load and response to interferon

OBJECTIVES: The interferon sensitivity-determining region (ISDR) in nonstructural region 5A (NS5A) of hepatitis C virus genotype 1b has been reported to correlate with response to interferon therapy and viral load. Recently the correlation between NS5A and response to interferon in genotype 2a was also reported. We examined the region of genotypes 2a and 2b corresponding to the ISDR of genotype 1b to elucidate its correlation with response to interferon and viral load. METHODS: The sequences of amino acid positions 2213–2248 in NS5A were determined in 39 patients with genotype 2a and 12 patients with genotype 2b. RESULTS: In the patients infected with genotype 2a, the number of amino acid substitutions in the ISDR-corresponding region compared with the consensus sequence of genotype 2a was significantly correlated with viral load (ρ = −0.541, p < 0.001) and with response to interferon therapy (p < 0.05); 83% of the patients with three or more substitutions obtained sustained responses, whereas only 44% of those with less than three substitutions obtained sustained responses. Multivariate analysis confirmed that the number of substitutions in the ISDR-corresponding region of genotype 2a was one of the independent predictors of response to interferon therapy (discriminant coefficient = 1.35, p < 0.001). CONCLUSIONS: Substitutions in the ISDR-corresponding region in NS5A of hepatitis C virus genotype 2a was confirmed to correlate to viral load and response to interferon therapy. In genotype 2b, further work must be considered because of the small number of patients studied.