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Biomedical subjects

R Tur-Kaspa

Publications and source records attributed to R Tur-Kaspa.

At least 37 records · Page 2Linked to original sources
PubMed2001

The addition of mycophenolate mofetil for suppressing hepatitis B virus replication in liver recipients who developed lamivudine resistance--no beneficial effect.

BACKGROUND: Mycophenolate mofetil is used as an immunosuppressive agent in liver transplant recipients. Its active compound, mycophenolic acid, also inhibits the replication of Epstein-Barr virus and human immunodeficiency virus. Based on a study indicating the effectiveness of mycophenolate mofetil on hepatitis B virus (HBV) replication in infected human hepatocyte cells in culture, we examined the efficacy of mycophenolate mofetil in suppressing HBV replication in lamivudine-resistant liver allograft recipients with recurrent HBV infection. METHOD: The study population included four liver allograft recipients (three males, one female), median age 51 years (range 41-57 years), with recurrent HBV infection who proved to be resistant to lamivudine. All received standard maintenance immunosuppression therapy. Median pretreatment serum alanine aminotransferase level was 75 mu/L (range 39-182 mu/L) and HBV DNA level (quantitative dot blot), 70 pg/ml (range: 10-5,000 pg/ml). Mycophenolate mofetil, 1.0 g p.o. twice daily, was administered for 8 weeks, concomitant with a reduction in the maintenance corticosteroid and cyclosporine doses. RESULTS: After mycophenolate mofetil was administered, the serum alanine aminotransferase level increased in two patients, did not change in one, and decreased in one. Serum HBV DNA levels increased in three patients and decreased (nonsignficantly) in only one patient. Two patients complained of abdominal pain and nausea. CONCLUSIONS: Mycophenolate mofetil at the dosage used is not effective in suppressing HBV replication after liver transplantation.

Adult↗
PubMed2001

Cell transformation induced by hepatitis C virus NS3 serine protease.

Persistent infection with hepatitis C virus (HCV) may lead to hepatocellular carcinoma (HCC). It has been suggested that HCV-encoded proteins are directly involved in the tumorigenic process. The HCV nonstructural protein NS3 has been identified as a virus-encoded serine protease. To study whether HCV NS3 has oncogenic activity, nontumorigenic rat fibroblast (RF) cells were stably transfected with an expression vector containing cDNA for the NS3 serine protease (nucleotides 3356-4080). The NS3 serine protease activity was determined in the transfected cells. The transfected cells grew rapidly and proliferated serum independently, lost contact inhibition, grew anchorage independently in soft agar and induced significant tumour formation in nude mice. Cells transfected with an expression vector containing a mutated NS3 serine protease (serine 139 to alanine at the catalytic site) showed no transforming abilities; their growth was dependent on serum and they did not grow anchorage independently in soft agar. Moreover, cells transfected with the NS3 serine protease and treated with the chymotrypsin inhibitors TPCK and PMSF (a serine protease inhibitor) lost their transforming feature. These results suggest that the NS3 serine protease of HCV is involved in cell transformation and that the ability to transform requires an active enzyme.

Animals↗
PubMed2001

Long-term experience with lamivudine therapy for hepatitis B virus infection after liver transplantation.

Hepatitis B virus (HBV) infection after orthotopic liver transplantation (OLT) is associated with a high recurrence rate and poor prognosis. This is the first study of the efficacy of long-term lamivudine therapy for patients with HBV infection after OLT. Eight patients (5 men, 3 women) aged 35 to 63 years (mean, 50 years) with HBV infection after OLT (6 patients, recurrent infection; 2 patients, de novo infection) were treated with lamivudine, 100 mg/d, on a compassionate-use basis. Before treatment, all had detectable HBV DNA in serum, and 5 patients (62.5%) had detectable serum hepatitis Be antigen (HBeAg). Duration of treatment was 24 to 50 months (mean, 36 months). Patients were monitored for serum alanine aminotransferase level (ALT), HBV DNA (by hybridization), hepatitis B surface antigen (HBsAg), and HBeAg before and after therapy, and liver histological findings were scored for inflammation and fibrosis. After treatment, 3 patients (32.5%) had undetectable HBV DNA by hybridization assay. None of the patients lost serum HBeAg and HBsAg, except for 1 patient who lost serum HBeAg and became serum antibody to HBeAg-positive. Serum ALT levels normalized in 5 patients (62.5%). Blinded histological assessment showed improvement in 1 patient, no change in 2 patients, and worsening in 5 patients. YMDD variants of HBV were detected in 5 patients (62.5%) within 9 to 20 months (mean, 13 months) of lamivudine therapy. Of these, 2 patients (40%) had hepatic failure (1 patient died of massive variceal bleed) and 3 patients remain clinically stable. Lamivudine therapy was continued in the latter patients. Although lamivudine is a potentially effective therapy for HBV infection after OLT, emergence of high mutation rates with long-term therapy, histological progression, and the possibility of hepatic failure point to the need to investigative combinations of antiviral therapy.

Adult↗
PubMed2001

Basal and post-methionine serum homocysteine and lipoprotein abnormalities in patients with chronic liver disease.

BACKGROUND: Lipoprotein abnormalities are commonly found in chronic liver diseases (CLDs), particularly hypercholesterolemia in primary biliary cirrhosis (PBC). However, affected patients may not be at increased risk of coronary heart disease. Cirrhotic patients display impaired methionine clearance, and an increased level of homocysteine, a methionine metabolite, is an independent risk factor for coronary heart disease. Thus, we hypothesized that the low risk of coronary heart disease in patients with CLD may be related to low serum levels of homocysteine. The aim of this study was to test this hypothesis after methionine load and to describe the serum lipoprotein profile in patients with PBC and in patients with hepatocellular liver disease. METHODS: Fifteen female patients (mean age, 58.2 +/- 11.7 years) with PBC, 15 female patients (mean age, 54.5 +/- 9.6 years) with other causes of CLD, and 15 healthy sex- and age-matched controls were given L-methionine (50 mg/kg of ideal body weight). Basal fasting serum homocysteine level and 2, 4, and 6 hours of post-methionine load were determined using high-performance liquid chromatography with a fluorometric detector. Levels of fasting serum cholesterol, triglycerides, high-density lipoprotein (HDL), low-density lipoprotein (LDL), lipoprotein (a) (Lp(a)), and apoprotein B were also determined. RESULTS: Results showed that mean basal and post-methionine load (6 hours) serum homocysteine levels were statistically significantly higher in the patients with PBC and with CLD than in the control group (P=0.04) and that levels of serum cholesterol, LDL, HDL, and apoprotein B were significantly higher in the PBC patients than in the other two groups (P < or = 0.05). There was no correlation between any of these parameters and the severity of liver disease. Serum HDL was significantly lower in the CLD group (P < or = 0.05) and correlated with severity of liver disease. There was no significant difference in serum cholesterol, LDL, or apoprotein B between the CLD group and the controls. Serum triglyceride and Lp(a) levels were similar for all three groups. CONCLUSIONS: In contrast to previous reports, the site of the methionine metabolic impairment was found to be below the homocysteine synthesis level. For most patients with CLD, factors other than serum homocysteine or Lp(a) are responsible for the reduction in the risk of coronary heart disease. Further studies with larger samples are needed.

Aged↗
PubMed2001

Hepatitis C infection in dialysis patients in Israel.

BACKGROUND: Hepatitis C virus is the major cause of acute and chronic hepatitis in patients with end-stage renal disease receiving replacement therapy. OBJECTIVES: To define the prevalence of HCV RNA in a population of patients on dialysis in Israel, to determine the relative risk of acquiring HCV infection while treated by hemodialysis or chronic ambulatory peritoneal dialysis, and to define the HCV genotypes in this population. METHODS: During 1995 we studied 162 dialysis patients. Information was obtained regarding the mode of dialysis, years of treatment, number of blood transfusions, and results of serological testing for HCV, hepatitis B virus, and human immunodeficiency virus. Anti-HCV antibodies were tested by a third-generation microparticle enzyme immunoassay. HCV RNA was determined by polymerase chain reaction. HCV genotyping was performed by a hybridization assay. RESULTS: HCV RNA was detected in 18% of the HD group and 7% of the CAPD group. The number of HCV RNA-positive patients was significantly higher in the HD than the CAPD group (P < 0.05). HCV RNA-positive HD patients were treated longer than the HCV RNA-negative patients (P < 0.02). CONCLUSIONS: Third-generation immunoassay proved to be highly sensitive (94%) and specific (91%) in identifying HCV RNA positivity. Several HCV subtypes were detected, 1b being the most frequent. Identification and isolation of infected HCV patients may minimize its spread in dialysis units and prevent cross-infection.

Adult↗
PubMed2000

Bcl-2 rearrangement in patients with chronic hepatitis C associated with essential mixed cryoglobulinemia type II.

Hepatitis C virus (HCV) infection is found in 80% to 90% of patients with essential mixed cryoglobulinemia (EMC) type II, which is associated with monoclonal IgMk produced by monoclonal B cells. It was investigated whether bcl-2 rearrangement is associated with the clonal B-cell proliferation of EMC induced by hepatitis C. The study groups were composed of 15 patients with HCV and EMC, 12 patients with HCV without EMC, and 7 patients with chronic liver disease (CLD) unrelated to HCV. Fluorescence in situ hybridization with probes was applied to JH and to bcl-2 to study whether JH/bcl-2 translocation was present in these patients. Thirteen of 15 (86%) of patients with HCV-related EMC had the JH/bcl-2 translocation, a significantly higher rate than in HCV patients without EMC (16%; P < .001). Bcl-2 rearrangement was not detected in the patients with CLD not related to HCV. The JH/bcl-2 translocation may constitute a pathogenetic link for the development of NHL in patients with HCV infection. (Blood. 2000;96:2910-2912)

Adult↗
PubMed2000

Extension of transplantation free time by lamivudine in patients with hepatitis B-induced decompensated cirrhosis.

BACKGROUND: Liver transplantation for hepatitis B virus (HBV)-induced cirrhosis carries a high risk of graft reinfection and poor prognosis. Active viral replication is considered a contraindication for transplantation in most centers. Lamivudine, a new nucleoside analog, is a potent inhibitor of HBV replication that has been used safely for pretransplantation suppression of HBV replication. METHODS: We report the pattern of response to lamivudine treatment in three consecutive patients with decompensated cirrhosis due to the replicative phase of chronic HBV infection. RESULTS: In addition to virological and biochemical response, impressive clinical improvement was noted in all three patients, with disappearance of the ascites and marked improvement of synthetic liver function tests. One patient converted to anti-hepatitis B surface and is free of symptoms 20 months after initiation of treatment. The other two patients experienced significant clinical improvement for 8 to 9 months and were removed from the waiting list for transplantation. However, progressive liver disease recurred in both patients--one underwent liver transplantation and the other is a candidate for the procedure. CONCLUSION: The administration of lamivudine for pretransplantation HBV suppression was associated with impressive clinical and biochemical improvement. Lamivudine may extend the transplantation free time in such patients. The mechanism of this desirable effect should be explored.

Adult↗
PubMed2000

Fulminant non--A-G viral hepatitis leading to liver transplantation.

BACKGROUND: All hepatotropic viruses are known to cause fulminant hepatic failure (FHF). However, in 30% to 40% of patients with FHF, the precise cause remains unknown. We aimed to better define this subgroup. METHODS: We evaluated the clinical course and outcome of 7 patients admitted during a 22-month period with fulminant viral hepatitis leading to liver transplantation; none had serologic or molecular evidence of hepatitis A, B, C, D, E, or G viral infection, thus the term non-A-G viral hepatitis. All known etiologies of FHF were excluded. RESULTS: All patients had prodromal symptoms suggestive of viral causes. Mean age was 30 years. The interval between onset of jaundice and appearance of encephalopathy was 23 days (range, 4-50 days). Five patients had grade III/IV encephalopathy. Serum alanine aminotransferase levels showed a single peak of activity. The duration between first symptoms and liver transplantation was 28 days (range, 12-71 days). Results of histological study of the explanted liver showed submassive (4 patients) or massive (3 patients) hepatocyte necrosis. In all patients, results of polymerase chain reaction analysis did not detect hepatitis B virus DNA, hepatitis C virus RNA, or hepatitis G virus RNA in the explanted liver. After transplantation, 2 patients showed (6 months later) increased liver enzyme levels of undetermined cause, and results of a liver biopsy showed mild lobular hepatitis; 1 patient had lymphoproliferative disorder (Epstein-Barr virus-originated); and 1 patient, aplastic anemia, which is known to be associated with seronegative viral hepatitis. The latter patient died, whereas the other 6 patients are alive (survival rate, 86%). CONCLUSIONS: Our patients with non-A-G viral hepatitis had a severe acute onset with progressive FHF requiring liver transplantation. There is some suggestion of recurrent viral disease after transplantation implicating other unknown viruses in the etiology.

Adolescent↗
PubMed2000

Mutations at vicinity of catalytic sites of hepatitis C virus NS3 serine protease gene isolated from hepatocellular carcinoma tissue.

The mechanism of hepatitis C virus (HCV) -induced hepatotocellular carcinoma (HCC) is still unknown, but in vitro studies clearly suggest that HCV proteins exert a direct effect on liver carcinogenesis. HCV NS3 serine protease is known to play a key role in the life cycle of the virus and may interact with the host cellular regulatory proteins. The aim of the present study was to conduct a genetic analysis of the HCV NS3 gene coding for the serine protease isolated from serum, tumor, and nontumor tissue of HCC patients. RNA was extracted and HCV cDNA was amplified by nested reverse transcriptase-polymerase chain reaction (RT-PCR). Sequence comparison yielded unique changes at the vicinity of the catalytic sites of the NS3 clones isolated only from HCC tissue. These changes included the insertion of a "large" and charged amino acid, substitution of a polar with a hydrophobic amino acid, and substitution of a charged with a polar amino acid. Those changes affect the electrostatic charge around the active site, and thus the activity and substrate specificity of the serine protease. This is the first study to define significant amino acid changes at the catalytic domain of the NS3 serine protease gene isolated from HCC tissue.

Amino Acid Sequence↗