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Biomedical subjects

M R Brunetto

Publications and source records attributed to M R Brunetto.

At least 109 records · Page 6Linked to original sources
PubMed1991

Hepatitis B virus replication modulates pathogenesis of hepatitis D virus in chronic hepatitis D.

Hepatitis D virus and hepatitis B virus nucleic acids were detected by Northern and Southern blot hybridization in the sera and livers of 85 chronic carriers of HBsAg and anti-hepatitis D followed up for a mean of 10 yr. We identified three subsets of patients: 13 with hepatitis D virus and hepatitis B virus viremia, 53 with serum hepatitis D virus RNA, but without hepatitis B virus DNA and 19 negative for both nucleic acids. Genomic and subgenomic forms of hepatitis D virus RNA were detected only in patients with hepatitis D virus and hepatitis B virus viremia. Histological findings and disease activity at admission were comparable in the three groups of patients, but the outcome was significantly worse in patients with active replication of both viruses; two of them died of terminal liver failure and hepatocellular carcinoma developed in two; the remaining patients had an uneventful course. These results suggest that active hepatitis B virus replication represents an important previously unrecognized determinant of severe liver damage in patients with chronic hepatitis D virus infection. Since hepatitis B virus provides the means for hepatitis D virus secretion and release from infected cells, active hepatitis B virus multiplication favoring the spread of hepatitis D virus from cell to cell may increase the pathogenetic potential of the defective agent.

Adolescent↗
PubMed1990

A precore-defective mutant of hepatitis B virus associated with e antigen-negative chronic liver disease.

The pathogenesis of chronic liver disease (CLD) due to persistent hepatitis B virus (HBV) infection has not been defined, but the disease activity is believed to correlate with the presence of hepatitis B e-antigen (HBeAg) antigenemia and high viremia. The molecular characterization of an HBV mutant isolated from an HBeAg-negative patient with severe CLD required amplification of the circulating HBV DNA (2 pg/ml) by the polymerase chain reaction (PCR). Direct sequencing of the nucleotides from five independent amplifications of the conserved precore region consistently revealed a G to A mutation in each of the two terminal codons of the precore region. Codon 28 was mutated from tryptophan-encoding TGG to a translational stop codon, TAG; codon 29 preceding the core initiation codon was changed from GGC to GAC. For biologic evaluation of these mutations on HBV replication and expression of HBeAg in vitro, HepG2 cells were transfected with cloned, recircularized mutant HBV DNA. The transfected cells contained subviral core particles in the cytoplasm and secreted mature HBV, without HBeAg, into the medium. The findings present the first evidence that complete HBV genomes can be amplified by PCR and are replication-competent in vitro. The data also indicate that HBeAg is not necessary for replication of HBV and furthermore suggest that HBeAg is not required for the progression of HBV-induced CLD.

Adult↗
PubMed1990

A new hepatitis B virus strain in patients with severe anti-HBe positive chronic hepatitis B.

In hepatitis B virus carriers who are anti-HBe positive despite ongoing viral replication (HBcAg in liver and HBV-DNA in serum) the natural course of hepatitis is severe and the response to interferon is low. We investigated whether a new hepatitis B virus (HBV) strain could be involved. A translational termination codon at the carboxyterminal end of the pre-C region responsible for the lack of HBeAg secretion was found in 18 of 19 HBV clones isolated from seven pedigreed patients with this clinical syndrome. The same findings were confirmed by direct sequencing. One of these patients underwent a liver transplant and HBV infection of the new liver resulted in high titered viremia and intrahepatic expression of HBcAg, without detectable HBeAg in serum. Another patient was superinfected by hepatitis delta virus (HDV) and developed high titres of total and IgM anti-HD. In spite of this, chronic hepatitis remained unchanged during 7 years of follow-up. These data strongly suggest that a viable precore minus mutant of hepatitis B virus is responsible for the lack of HBeAg in the serum of these patients. The HBV variant may explain the peculiar geographic distribution of anti-HBe positive hepatitis. The variations in the virus genome sequence may cause the more severe form of liver disease and modify the pathogenicity in the case of HDV superinfection.

Adult↗
PubMed1989

Natural course and response to interferon of chronic hepatitis B accompanied by antibody to hepatitis B e antigen.

The course of chronic hepatitis B was studied in 30 patients who had antibody to hepatitis e antigen and hepatitis B virus DNA in the serum and hepatitis B core antigen in the liver. Over a 2-year period, no patient experienced a sustained spontaneous remission of disease, and follow-up liver histology revealed worsening of the disease in four patients. After 2 years of observation, 24 patients were allocated randomly to one of two groups: 12 patients served as untreated controls and 12 received recombinant human alpha-interferon-2a in a dose of 9 million units intramuscularly three times weekly for 16 weeks. Patients who remained viremic after 16 weeks received 3 million units three times weekly for an additional 8 weeks. Abnormal amino-transferases and serum hepatitis B virus DNA persisted without appreciable changes in all untreated patients. Hepatitis B virus DNA rapidly became undetectable and serum aminotransferases fell to normal in eight treated patients. After the end of treatment, hepatitis B virus DNA became detectable once again in seven patients, in six of whom a peak of aminotransferases (range: 256 to 850 units per liter) ensued; subsequently, hepatitis B virus DNA disappeared, and serum aminotransferases again fell to normal in two of the seven. Overall, hepatitis B virus DNA was no longer detectable in serum and liver histology improved in three treated patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Relationship between the intrahepatic expression of 'e' and 'c' epitopes of the nucleocapsid protein of hepatitis B virus and viraemia.

The relationship between hepatitis B viraemia and intrahepatic HBV nucleocapsid proteins (HBcAg and HBeAg) was studied in 18 patients with chronic hepatitis B. Monoclonal antibodies (MoABs) were obtained in BALB/c mice primed with recombinant HBV nucleocapsid proteins. Four MoABs reacting with recombinant proteins gave positive results in competitive assays. Two reacted as anti-HBc and two as anti-HBe. One of them showed a strong affinity for the cytoplasmic, membrane-bound antigen (P23e) of infected hepatocytes while the latter showed a higher specificity for serum HBeAg than for the intrahepatic antigen. Anti-HBc MoABs had a staining capacity for liver cell nuclei comparable with that of polyclonal antibodies. Overall the anti-HBc MoABs stained the liver cell nuclei in 86% of cases, while anti-HBe MoABs stained in 58% of cases. The hepatocyte cytoplasm was stained by anti-HBc MoABs and anti-HBe MoABs in 64% and 72% of cases respectively. Not one of 12 control liver biopsies was stained. Viraemia (HBV-DNA) was measured by dot blot hybridization and was correlated with the number of hepatocytes containing the nucleocapsid antigen. The highest levels of HBV-DNA (greater than 10(8) genomes/ml) were detected in patients with prevalent nuclear staining while the lowest ones were observed in those with prevalent cytoplasmic expression of this antigen. The application of anti-HBV-nucleocapsid MoABs in diagnostics requires careful scrutiny since some are specific for the circulating antigen while others show a higher affinity for the intrahepatic antigen.

Antibodies, Monoclonal↗
PubMed1988

Inhibition of hepatitis B virus replication by vidarabine monophosphate conjugated with lactosaminated serum albumin.

Vidarabine (ara A) produces severe dose-dependent side-effects. To examine whether its monophosphate ester (ara-AMP) can be effective in the treatment of chronic hepatitis B when given in reduced dosage as a conjugate with lactosaminated human serum albumin (L-HSA), which selectively enters hepatocytes, five patients with chronic type B hepatitis (HBsAg/HBV-DNA positive for at least 2 years) were treated with the conjugate. The daily dose of conjugate given (35 mg/kg) contains 1.5 mg ara-AMP, whereas the usual daily dose of free ara-AMP is 5-10 mg/kg. In three patients HBV-DNA fell to undetectable levels and remained negative in two; in one of them anti-HBe developed. In the other two patients HBV-DNA decreased but was detectable during treatment--one received three cycles of therapy, and became HBV-DNA negative and anti-HBe positive 45 days after the end of treatment; the other remained HBeAg/HBV-DNA positive. No adverse effects were observed, and biochemical variables (including aminotransferases) remained unchanged or decreased with viraemia. No antibodies (IgM and IgG classes) that bound the conjugate were detected. Thus L-HSA-ara-AMP inhibits HBV replication as well as free ara-AMP but at a third to a sixth of the dose.

Adult↗
PubMed1988

Serum markers of hepatitis B virus replication, liver histology and intrahepatic expression of hepatitis B core antigen.

The presence and distribution of hepatitis B core antigen (HBcAg) was studied in the liver of 227 chronic carriers of hepatitis B surface antigen (HBsAg) to investigate its relationship with serum HBV-DNA, the status of hepatitis B 'e' antigen/antibody (HBeAg/anti-HBe) and the underlying liver disease. HBcAg was detected in 144 of the 227 (63%) liver specimens and HBV-DNA in 132 (58%) of the corresponding sera. Serum HBV-DNA showed a constant link with intrahepatic HBcAg. Out of 96 HBeAg-positive patients, 91 (95%) had HBcAg in the liver and 85 (89%) had HBV-DNA in serum. Overall there was a significant link between HBeAg and HBV-DNA in serum, but there was no correlation in 58 out of 227 (26%) cases. In HBeAg/HBV-DNA-positive carriers, HBcAg expression was predominantly nuclear. It was nuclear and cytoplasmic in patients with the highest levels of viremia. Eleven out of 13 (85%) HBV-DNA-positive patients who had only cytoplasmic HBcAg were HBcAg-negative and had low levels of HBV-DNA. Nine of 13 (69%) patients with exclusively cytoplasmic HBcAg had severe chronic liver disease. Neither the presence of HBV-DNA and HBeAg in serum nor the nuclear localization of HBcAg were associated with the severity of liver damage. In the group of HBV-DNA-positive patients (132), the presence of liver disease was significantly connected with the absence of HBeAg in serum (P less than 0.05; C.L. 3-35).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Rapidly progressive HBsAg-positive hepatitis in Italy. The role of hepatitis delta virus infection.

Serum or liver markers of hepatitis delta virus (HDV) infection were found in 20 of 22 (90%) Italian patients presenting with an ostensible type B hepatitis that ran an accelerated course to cirrhosis. The features of the illness conformed to a syndrome of HDV infection in young males carrying the hepatitis B surface antigen (HBsAg); a latent HBsAg state was documented in many patients by a history of prior exposure to the hepatitis B virus (HBV) or by the absence of IgM antibodies to the HB core antigen. Characteristic of the disease were the clinical overture as a severe hepatitis, the lobular involvement by an extensive necroinflammatory reaction, the exuberant expression of intrahepatic hepatitis delta antigen and an atypical HBV profile of inactive infection or accelerated seroconversion from HBeAg to anti-HBe. Superimposed upon HBV infection, HDV may create a rapidly progressive course which resembles very aggressive hepatitis B but is infrequently observed in hepatitis B alone.

Adolescent↗
PubMedDate not supplied

Interferon treatment of chronic hepatitis B surface antigen (HBsAg) carriers. A description of the activation profiles of natural killer cells obtained with different schedules of administration in three subsets of carriers.

By monitoring immunobiological parameters known to be influenced by interferon (IFN), the natural killer (NK) cell activity of 10 low replication (anti-HBe) virus B-DNA (HBV-DNA) hepatitis patients receiving rIFN alpha-A, of 5 anti-HBe/delta positive hepatitis patients treated with rIFN alpha-2, and of 6 high replication (HBeAg) HBV-DNA hepatitis patients on lymphoblastoid IFN was followed-up during therapy. Overall, strong and significant (p less than 0.01) shift to increase segregated with the low replication subset; the delta positive subset was non-significantly increased (0.30 greater than p greater than 0.2); the high replication subset was depressed in a nearly significant (0.10 greater than p greater than 0.05) manner. Kinetic studies showed the activation of the first subset to follow an early steep rise and a subsequent plateau as fitted with a quadratic curve (p = 0.02); an early rise and a depression at 2 months delineated a complex cubic model (p = 0.06) in the high replication subset. The profound NK depression was clinically witnessed by a sharp rise of the aminotransferases and following drop of viremia. The study shows that i. discrete patterns of NK response as amenable to mathematical models may associate to differential patterns of virus B replication in patients responding to IFN; ii. point(s) on the NK curve may acquire clinical meaning as they coincide with a consensual or opposite shift of a clinical index.

Adult↗
PubMedDate not supplied

Nucleic acid hybridization in viral hepatitis research.

Nucleic acid hybridization is extremely important in viral hepatitis research and the newly emerging techniques are now becoming an indispensable resource also in the diagnostic laboratory. This paper provides information on methods currently used for detection of viral nucleic acids with special emphasis on the importance of hepatitis B virus DNA in the serum. Herein, we describe the procedures for preparation and labeling of DNA probes and the principles that regulate dot, slot and Southern blot hybridization. Advantages and shortcomings of filter hybridization are discussed together with the alternative approaches to it. Finally, a collection of laboratory protocols is presented in Appendix #1.

DNA Probes↗