Chronic hepatitis B

Hepatology

Volumn 34, Issue 6, 2001, Pages 1225-1241

  Lok, Anna S F ^a   McMahon, Brian J ^b  

^a UNIVERSITY OF MICHIGAN MEDICAL SCHOOL   (United States)

^b CENTERS FOR DISEASE CONTROL AND PREVENTION   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ADEFOVIR DIPIVOXIL; ALANINE AMINOTRANSFERASE; ALPHA FETOPROTEIN; ALPHA INTERFERON; ANTIVIRUS AGENT; EMTRICITABINE; ENTECAVIR; FAMCICLOVIR; INTERFERON; LAMIVUDINE; PENCICLOVIR; PREDNISONE; STEROID; THYMOSIN; VIRUS DNA;

ADULT; ANIMAL MODEL; CANCER SCREENING; CHILD; CHRONIC HEPATITIS; CLINICAL TRIAL; CONTROLLED CLINICAL TRIAL; CONTROLLED STUDY; COST EFFECTIVENESS ANALYSIS; DRUG INDUCED DISEASE; HEPATITIS B; HEPATITIS B VIRUS; HUMAN; LIVER CELL CARCINOMA; LIVER FUNCTION TEST; MAJOR CLINICAL STUDY; META ANALYSIS; MULTICENTER STUDY; NEPHROTOXICITY; NONHUMAN; PATIENT COUNSELING; PHASE 1 CLINICAL TRIAL; PHASE 2 CLINICAL TRIAL; PRIORITY JOURNAL; RANDOMIZED CONTROLLED TRIAL; REVIEW; SCREENING TEST; VIRUS HEPATITIS; VIRUS INFECTION; VIRUS REPLICATION; VIRUS TRANSMISSION;

EID: 0035189597     PISSN: 02709139     EISSN: None     Source Type: Journal    
DOI: 10.1053/jhep.2001.29401     Document Type: Article

References (229)

1. Management of hepatitis B 2000, Summary of a workshop
2. Infectious Diseases Society of America quality standards for infectious diseases: Purpose of quality standards for infectious diseases
3. Hepatitis B virus infection
4. Seroepidemiology of hepatitis B virus infection in the United States
5. Hepatitis B virus: A comprehensive strategy for limiting transmission in the United States through universal childhood vaccination. Recommendations of the Immunization Practices Advisory Committee (ACIP)
6. Hepatitis B virus: The major etiology of hepatocellular carcinoma
7. Hepatocellular carcinoma and viral hepatitis
8. Hepatitis B virus biology
9. Hepadnaviridae and their replication
10. Biologic properties of hepatitis B viral genomes with mutations in the precore promoter and precore open reading frame
11. Effects of a naturally occurring mutation in the hepatitis B virus basal core promoter on precore gene expression and viral replication
12. Antiviral chemotherapy for chronic hepatitis B infection: Lessons learned from treating HIV-infected patients
13. Hepatitis B: Global importance and need for control
14. Strategies to prevent and control hepatitis B and C virus infections: A global perspective
15. Hepatitis B: Evolving epidemiology and implications for control
16. Recommendations for protection against viral hepatitis. Recommendations of the Immunization Practices Advisory Committee (ACIP)
17. Prevention of perinatal transmission of hepatitis B virus: Prenatal screening of all pregnant women for hepatitis B surface antigen. Recommendations of the Immunization Practices Advisory Committee (ACIP)
18. Hepatitis B in patients with HIV infection: Relationship to AIDS and patient survival
19. Prevalence, patterns and course of past hepatitis B virus infection in intravenous drug users with HIV-1 infection
20. Survival of hepatitis B virus after drying and storage for one week
21. Hepatitis B surface antigen in saliva, impetiginous lesions, and the environment in two remote Alaskan villages
22. Prevention of perinatally transmitted hepatitis B virus infections with hepatitis B immune globulin and hepatitis B vaccine
23. Incidence of hepatitis B virus in preschool children in Taiwan
24. Age- and sex-related study of hepatitis B virus chronic carrier state in infants from an endemic area
25. Acute hepatitis B virus infection: Relation of age to the clinical expression of disease and subsequent development of the carrier state
26. Natural history of acute hepatitis B surface antigen-positive hepatitis in Greek adults
27. Clinical aspects of the interactions between human immunodeficiency virus and the hepatotropic viruses
28. The effect of concurrent human immunodeficiency virus infection on chronic hepatitis B: A study of 150 homosexual men
29. Seroconversion from hepatitis B e antigen to antibody in chronic type B hepatitis
30. Natural history of liver disease in chronic hepatitis B surface antigen carriers: Survey of 100 patients from Great Britain
31. Clinical and histological events preceding hepatitis B e antigen seroconversion in chronic type B hepatitis
32. Clinical, virologic and histologic outcome following seroconversion from HBeAg to anti-HBe in chronic hepatitis type B
33. Spontaneous hepatitis e antigen to antibody seroconversion and reversion in Chinese patients with chronic hepatitis B virus infection
34. A longitudinal follow-up of asymptomatic hepatitis B surface antigen-positive Chinese children
35. The significance of spontaneous hepatitis e antigen seroconversion in childhood: With special emphasis on the clearance of hepatitis e antigen before 3 years of age
36. Changes in serum hepatitis B DNA and aminotransferase levels during the course of chronic hepatitis B virus infection in children
37. Acute exacerbations in Chinese patients with chronic hepatitis B (HBV) virus infection: Incidence, predisposing factors and etiology
38. Regional prevalence of hepatitis B, Delta, and human immunodeficiency virus infection in Southern Africa: A large population survey
39. Long-term outcome of chronic type B hepatitis in patients who acquire hepatitis B infection in childhood
40. Clinical and histological outcome after hepatitis B e antigen to antibody seroconversion in children with chronic hepatitis B
41. The impact of hepatitis B mass immunisation campaign on the incidence and risk factors of acute hepatitis B in Italy
42. The natural history of asymptomatic hepatitis B surface antigen carriers
43. Serologic and clinical outcomes of 1536 Alaska Natives chronically infected with hepatitis B virus
44. Influence of human immunodeficiency virus infection on chronic hepatitis B in homosexual men
45. Long-term follow-up study of symptomatic HBsAg-positive voluntary blood donors in Austria: A clinical and histologic evaluation of 242 cases
46. Spontaneous reactivation of chronic hepatitis B virus infection
47. Acute exacerbation in chronic type B hepatitis: Comparison between HBeAg and antibodypositive patients
48. Long-term follow-up of anti-HBe-positive chronic active hepatitis B
49. Hepatitis B e antigen-negative chronic hepatitis B in Hong Kong
50. Natural course and response to interferon of chronic hepatitis B accompanied by antibody to hepatitis B e antigen
51. Genotypes, nt 1858 variants, and geographic origin of hepatitis B virus - Large-scale analysis using a new genotyping method
52. Incidence and clinical significance of hepatitis B virus precore gene translation initiation mutations in e antigen-negative patients
53. Precore mutant hepatitis B virus infection and liver disease
54. Hepatitis B virus infection: Precore mutants and its relation to viral genotypes and core mutations
55. Frequency of hepatitis B virus e-minus mutants varies among patients from different areas of China
56. The clinical significance of core promoter and precore mutations during the natural course and interferon therapy in patients with chronic hepatitis B
57. Comparison of anti-HBe-positive and HBe-antigen-positive chronic hepatitis B in France
58. Variations of hepatitis B virus core gene sequence in Western patients with chronic hepatitis B virus infection
59. Rapid detection of genotypes and mutations in the pre-core promoter and the pre-core region of hepatitis B virus genome: Correlation with viral persistence and disease severity
60. Hepatitis B e antigen negative chronic hepatitis B: From clinical recognition to pathogenesis and treatment
61. The long-term course of chronic hepatitis B
62. Wild-type and e antigen-minus hepatitis B viruses and course of chronic hepatitis
63. Precore mutant of hepatitis B virus prevails in acute and chronic infections in an area in which hepatitis B is endemic
64. Hepatitis B virus precore mutants in serum and liver of Southern African blacks with hepatocellular carcinoma
65. Mutations in the pre-core region of hepatitis B virus serve to enhance the stability of the secondary structure of the pre-genome encapsidation signal
66. Mutation preventing formation of hepatitis B e antigen in patients with chronic hepatitis B infection
67. Hepatitis B virus with mutations in the core promoter for an e antigen-negative phenotype in carriers with antibody to e antigen
68. Subtypes, genotypes and molecular epidemiology of the hepatitis B virus as reflected by sequence variability of the S-gene
69. Clearance of HBsAg in seven patients with chronic hepatitis
70. Incidence, determinants and significance of delayed clearance of serum HBsAg in chronic hepatitis B virus infection: A prospective study
71. Hepatitis B virions isolated with antibodies to the pre-S1 domain reveal occult viremia in surface antigen negative/antibody-positive carriers by polymerase chain reaction
72. Prospective study of hepatocellular carcinoma and liver cirrhosis in asymptomatic chronic hepatitis B virus carriers
73. The development of cirrhosis in patients with chronic type B hepatitis: A prospective study
74. Natural history and prognostic factors for chronic hepatitis type B
75. Survival and prognostic factors in 366 patients with compensated cirrhosis type B: A multicenter study
76. Survival and prognostic indicators in hepatitis B surface antigen-positive cirrhosis of the liver
77. Occurrence of hepatocellular carcinoma and decompensation in western European patients with cirrhosis type B
78. Long-term follow-up of HBeAg-positive patients treated with interferon alfa for chronic hepatitis B
79. Long-term outcome of hepatitis B e antigen-positive patients with compensated cirrhosis treated with interferon alfa
80. Long-term beneficial effect of interferon therapy in patients with chronic hepatitis B virus infection
81. Long-term follow-up of patients with chronic hepatitis B treated with interferon alfa
82. Natural course after the development of cirrhosis in patients with chronic type B hepatitis: A prospective study
83. Pathogenic role of hepatitis B virus in hepatitis B surface antigen-negative decompensated cirrhosis
84. Sero-clearance of hepatitis B surface antigen in chronic carriers does not necessarily imply a good prognosis
85. Epidemiological factors affecting the severity of hepatitis C virus-related liver disease: A French survey of 6, 664 patients
86. Interactions between human immunodeficiency virus-1, hepatitis delta virus and hepatitis B virus infections in 260 chronic carriers of hepatitis B virus
87. Hepatitis D
88. Epidemiology and long-term consequences of hepatitis Delta virus infection in the Yucpa Indians of Venezuela
89. Chronic hepatitis D: A vanishing disease?. An Italian multinational study
90. Hepatitis B virus-associated coinfection and superinfection with delta agent: Indistinguishable disease with different outcome
91. Influence of hepatitis delta virus infection on progression to cirrhosis in chronic hepatitis type B
92. Influence of hepatitis delta virus infection on morbidity and mortality in compensated cirrhosis type B
93. Prevention of hepatitis A through active or passive immunization: Recommendations of the Advisory Committee on Immunization Practices (ACIP)
94. Quantitative assays for hepatitis B virus DNA: Standardization and quality control
95. Comparison of plasma virus loads among individuals infected with hepatitis C virus (HCV) genotypes 1, 2, and 3 by Quantiplex HCV RNA assay versions 1 and 2, Roche Monitor assay, and an in-house limiting dilution method
96. Routine detection and quantification of hepatitis B virus DNA in clinical laboratories: Performance of three commercial assays
97. Classification of chronic hepatitis: Diagnosis, grading and staging
98. Formulation and application of a numerical scoring system for assessing histological activity in asymptomatic chronic active hepatitis
99. Histological grading and staging of chronic hepatitis
100. Intraobserver and Interobserver variations in liver biopsy interpretation in patients with chronic hepatitis C
101. Survival in chronic hepatitis B. An analysis of 379 patients
102. Susceptiblility of chronic symptomless HBsAg carriers to ethanol-induced hepatic damage
103. The hepatitis B carrier state - A follow-up study of 100 consecutive cases
104. Interaction between hepatitis B virus and alcohol consumption in liver cirrhosis: An epidemiologic study
105. The effect of habitual alcohol drinking on the development of type B chronic hepatitis, liver cirrhosis and hepatocellular carcinoma
106. Synergism of chronic alcoholism and hepatitis B infection in liver disease
107. Prevalence of isolated antibody to hepatitis B core antigen in an area endemic for hepatitis B virus infection: Implications in hepatitis B vaccination programs
108. Clinical significance and management when antibody to hepatitis B core antigen is the sole marker for HBV infection
109. Prevention of the HBsAg carrier state in newborn infants of mothers who are chronic carriers of HBsAg and HBeAg by administration of hepatitis-B vaccine and hepatitis-B immunoglobulin
110. Outcome of perinatal hepatitis B virus exposure is dependent on maternal virus load
111. Transmission of hepatitis B virus to multiple patients from a surgeon without evidence of inadequate infection control
112. The infected health care provider
113. Recommendations for preventing transmission of human immunodeficiency virus and hepatitis B virus to patients during exposureprone invasive procedures
114. Serologic markers of hepatitis B virus and alpha-fetoprotein levels preceding primary hepatocellular carcinoma in Alaskan Eskimos
115. Serum alpha-fetoprotein estimations and doubling time in hepatocellular carcinoma: Influence of therapy and possible value in early detection
116. Early detection of hepatocellular carcinoma
117. Growth rate of asymptomatic hepatocellular carcinoma and its clinical implications
118. Primary prevention of hepatocellular carcinoma
119. Screening for hepatocellular carcinoma in Alaska Natives infected with chronic hepatitis B: A 16-year population-based study
120. Long-term outcome after surgery for asymptomatic small hepatocellular carcinoma
121. Mass screening for hepatocellular carcinoma: Experience in Hokkaido, Japan
122. Screening for hepatocellular carcinoma in chronic carriers of hepatitis B virus: Incidence and prevalence of hepatocellular carcinoma in a North American urban population
123. Early detection of hepatocellular carcinoma by real-time ultrasonography
124. Treatment of small hepatocellular carcinomas
125. Treatment of hepatocellular carcinoma associated with cirrhosis in the era of liver transplantation
126. Nonresectional therapies for hepatocellular carcinoma
127. Treatment of hepatocellular carcinoma: Value of percutaneous microwave coagulation
128. A new, effective, and safe therapeutic option using proton irradiation for hepatocellular carcinoma
129. Tumor ablation with radio-frequency energy
130. Efficacy of a surveillance program for early detection of hepatocellular carcinoma
131. Prospective study of early detection of hepatocellular carcinoma in patients with cirrhosis
132. Screening for hepatocellular carcinoma in patients with Child's A cirrhosis: An 8 year prospective study by ultrasound and alpha-fetoprotein
133. Hepatocellular carcinoma in Italian patients with cirrhosis
134. Effectiveness of periodic checkup by ultrasonography for the early diagnosis of hepatocellular carcinoma
135. Clinical usefulness of Des-γ-carboxy prothombin in early diagnosis of hepatocellular carcinoma
136. Plasma abnormal prothrombin levels in patients with small hepatocellular carcinoma
137. Plasma Des-γ-carboxy prothombin in early stage of hepatocellular carcinoma
138. Diagnostic value of serum γ-glutamyl transferase isoenzyme for hepatocellular carcinoma a 10-year study
139. Serum α-L-fucosidase activity and tumor size in hepatocellular carcinoma
140. Serum α-L-fucosidase activity and early detection of hepatocellular carcinoma
141. The usefulness of determining Des-γ-carboxy prothombin by sensitive enzyme immunoassay in the early diagnosis of patients with hepatocellular carcinoma
142. Serum Des-gamma-carboxy prothombin levels determined by a new generation of sensitive immunoassays in patients with small-sized hepatocellular carcinoma
143. Early detection of hepatocellular carcinoma increases the chance of treatment: Hong Kong experience
144. Ultrasound follow-up of patients at risk for hepatocellular carcinoma: Results of a prospective study on 360 cases
145. Analysis of cost-effectiveness of different strategies for hepatocellular carcinoma screening in hepatitis B virus carriers
146. Cost effectiveness of thrombolytic therapy with tissue plasminogen activator as compared with streptokinase for acute myocardial infarction
147. Effect of alpha-interferon treatment in patients with hepatitis B e antigen-positive chronic hepatitis B
148. Which patients with chronic hepatitis B virus infection will respond to alpha-interferon therapy?
149. A randomized, controlled trial of interferon alfa-2b alone and after prednisone withdrawal for the treatment of chronic hepatitis B
150. A controlled trial of interferon with or without prednisone priming for chronic hepatitis B
151. Placebo-controlled trial of recombinant alpha 2-interferon in Chinese HBsAg-carrier children
152. Effect of recombinant alpha 2 interferon with or without prednisone in Chinese HBsAg carrier children
153. Long-term follow-up in a randomised controlled trial of recombinant alpha 2-interferon in Chinese patients with chronic hepatitis B infection
154. Lymphoblastoid interferon alfa with or without steroid pretreatment in children with chronic hepatitis B: A multicenter controlled trial
155. Interferon alfa therapy for chronic hepatitis B in children: A multinational randomized controlled trial
156. Interferon-alpha treatment of chronic hepatitis B in childhood: A consensus advice based on experience in European children
157. Interferon-alpha therapy for chronic hepatitis B in children: A meta-analysis
158. A randomized, controlled trial of a 24-month course of interferon alfa 2b in patients with chronic hepatitis B who had hepatitis B virus DNA without hepatitis B e antigen in serum
159. A randomized controlled trial of lymphoblastoid interferonalpha in patients with chronic hepatitis B lacking HBeAg
160. Interferon alfa-2b treatment of HBeAg negative/serum HBV DNA positive chronic active hepatitis type B
161. Anti-HBe-positive chronic hepatitis B with HBV-DNA in the serum response to a 6-month course of lymphoblastoid interferon
162. Long term response to therapy of chronic anti-HBepositive hepatitis B is poor independent of type and schedule of interferon
163. Long-term follow up after initial response to interferon therapy in patients with HBeAg negative chronic hepatitis B
164. The long-term outcome of interferon-alfa treated and untreated patients with HBeAg negative chronic hepatitis B
165. Retreatment of chronic hepatitis B e antigen-positive patients with recombinant interferon alfa-2a
166. Low-dose, titratable interferon alfa in decompensated liver disease caused by chronic infection with hepatitis B virus
167. Interferon alfa for patients with clinically apparent cirrhosis due to chronic hepatitis B
168. A controlled trial of human lymphoblastoid interferon in chronic hepatitis B in Italy
169. Lymphoblastoid interferon therapy of chronic HBV infection. A comparison of 12 vs. 24 weeks of thrice weekly treatment
170. Interferon alfa for chronic hepatitis B infection: Increased efficacy of prolonged treatment
171. Prednisone-interferon combination in the treatment of chronic hepatitis B: Direct and indirect meta-analysis
172. Prednisolone withdrawal therapy enhances the effect of human lymphoblastoid interferon in chronic hepatitis B
173. Cost-effectiveness of interferonalpha 2b treatment for hepatitis B e antigen-positive chronic hepatitis B
174. Long-term follow-up of chronic hepatitis B patients treated with interferon alfa
175. Long-term remission of chronic hepatitis B after alphainterferon therapy
176. The long-term effect of treatment with interferon-alpha 2a in chronic hepatitis B
177. Long-term follow-up of hepatitis B chronic carriers who responded to interferon therapy
178. Persistence of hepatitis B virus DNA in the liver after loss of HBsAg in chronic hepatitis B
179. Long term effect of alpha interferon in children with chronic hepatitis B
180. Lamivudine as initial treatment for chronic hepatitis B in the United States
181. A one-year trial of lamivudine for chronic hepatitis B
182. Lamivudine and alpha interferon combination treatment of patients with chronic hepatitis B infection: A randomised trial
183. Effects of extended lamivudine therapy in Asian patients with chronic hepatitis B
184. Extended lamivudine treatment in patients with chronic hepatitis B enhances hepatitis B e antigen seroconversion rates: Results after 3 years of therapy
185. Incremental increases in HBeAg seroconversion and continued ALT normalization in Asian chronic HBV (CHB) patients treated with lamivudine for four years
186. Pretherapy alanine transaminase level as a determinant for hepatitis B e antigen seroconversion during lamivudine therapy in patients with chronic hepatitis B
187. Predictors of HBsAg seroconversion in chronic hepatitis B patients treated with lamivudine
188. An international double-blind placebocontrolled trial of lamivudine in 286 children with chronic hepatitis B (CHB)
189. Efficacy of lamivudine in patients with hepatitis B e antigen-negative/hepatitis B virus DNA-positive (precore mutant) chronic hepatitis B
190. Long-term follow-up of patients with anti-HBe/HBV DNApositive chronic hepatitis B treated for 12 months with lamivudine
191. Evolution of hepatitis B virus polymerase gene mutations in hepatitis B e antigen-negative patients receiving lamivudine therapy
192. Efficacy of long-term lamivudine monotherapy in patients with hepatitis B e antigen-negative chronic hepatitis B
193. Long-term therapy of chronic hepatitis B with lamivudine
194. Response of pre-core mutant chronic hepatitis B infection to lamivudine
195. Post lamivudine treatment follow-up of patients with HBeAg negative chronic hepatitis B
196. A placebo controlled study of lamivudine and interferon alpha 2b in patients with chronic hepatitis B who previously failed interferon therapy
197. A multicenter United States-Canadian trial to assess lamivudine monotherapy before and after liver transplantation for chronic hepatitis B
198. Lamivudine treatment for decompensated cirrhosis resulting from chronic hepatitis B
199. Lamivudine treatment in patients with severely decompensated cirrhosis due to replicating hepatitis B infection
200. Determinants of survival in 133 patients with decompensated chronic hepatitis B treated with lamivudine
201. Durable HBeAg and HBsAg seroconversion after lamivudine for chronic hepatitis B
202. Hepatitis B e antigen seroconversion after lamivudine therapy is not durable in patients with chronic hepatitis B in Korea
203. Identification and characterization of mutations in hepatitis B virus resistant to lamivudine
204. Nomenclature for antiviral-resistant human hepatitis B virus mutations in the polymerase region
205. Acute exacerbation and hepatitis B virus clearance after emergence of YMDD motif mutation during lamivudine therapy
206. Hepatitis-B-virus resistance to lamivudine given for recurrent infection after orthotopic liver transplantation
207. Mutation in HBV RNA-dependent DNA polymerase confers resistance to lamivudine in vivo
208. Hepatitis B virus mutants associated with 3TC and famciclovir administration are replication defective
209. YMDD motif in hepatitis B virus DNA polymerase influences on replication and lamivudine resistance: A study by in vitro full-length viral DNA transfection
210. A preliminary trial of lamivudine for chronic hepatitis B infection
211. Lamivudine is effective in suppressing hepatitis B virus DNA in Chinese hepatitis B surface antigen carriers: A placebo-controlled trial
212. Acute exacerbation of chronic hepatitis B virus infection after withdrawal of lamivudine therapy
213. A randomized, placebo-controlled study to evaluate the efficacy of 12-month famciclovir treatment in patients with chronic hepatitis B e antigen-positive hepatitis B
214. Hepatitis B virus polymerase mutations during antiviral therapy in a patient following liver transplantation
215. Loss of serum HBV DNA and HBeAg and seroconversion following short-term (12 weeks) adefovir dipivoxil therapy in chronic hepatitis B: Two placebo controlled phase II studies
216. Mutations in hepatitis B DNA polymerase associated with resistance to lamivudine do not confer resistance to adefovir in vitro
217. Adefovir dipivoxil for the treatment of lamivudine-resistant hepatitis B mutants
218. Anti-hepatitis B virus (HBV) activity and pharmacokinetics of FTC in a 2 month trial in HBV infected patients
219. A study of oral entecavir given for 28 days in both treatment-naive and pre-treated subjects with chronic hepatitis
220. Influence of B domain mutation (L528M) of the hepatitis B virus polymerase on replication ability and resistance to nucleoside analogues
221. A randomized controlled trial of thymosin-alphal versus interferon alfa treatment in patients with hepatitis B e antigen antibody- and hepatitis B virus DNA-positive chronic hepatitis B
222. Efficacy of thymosin alphal in patients with chronic hepatitis B: A randomized, controlled trial
223. Thymosin alpha1 treatment of chronic hepatitis B: Results of a phase III multicentre, randomized, double-blind and placebo-controlled study
224. A randomized, controlled study of thymosin-alpha1 therapy in patients with anti-HBe, HBV-DNA-positive chronic hepatitis B
225. Combination therapy with lamivudine and famciclovir for chronic hepatitis B-infected Chinese patients: A viral dynamics study
226. A randomized controlled trial of a 12-month course of recombinant human interferon-alpha in chronic delta (type D) hepatitis: A multicenter Italian study
227. Treatment of chronic hepatitis D with interferon alfa-2a
228. Influence of alfa interferon on the natural history of chronic hepatitis D: Dissociation of histologic and virologic response
229. Lamivudine for chronic delta hepatitis