PubMed Health⌕ Search

Biomedical subjects

E Aragona

Publications and source records attributed to E Aragona.

10 recordsLinked to original sources
PubMed1992

Analysis of hepatocellular proliferation: study of archival liver tissue is facilitated by an endogenous marker of DNA replication.

Assessment of liver regeneration with endogenous genes that are expressed during DNA replication is physiological, specific and direct. To determine whether H3 histone messenger RNA expression (which is tightly coupled with DNA synthesis) could be used for this purpose, we initially examined liver regeneration in a mouse model. After partial hepatectomy, RNA transblot studies showed induction of H3 histone messenger RNA expression in regenerating mouse livers. In situ molecular hybridization demonstrated that the overall pattern of H3 histone messenger RNA expression correlated with [3H]thymidine labeling of hepatocytes. After partial hepatectomy, H3 histone messenger RNA expression in hepatocytes peaked at 48 hr (greater than 60 times greater than at 24 hr; p less than 0.001) and then rapidly declined. Although hepatocyte labeling with [3H]thymidine showed similar kinetics of liver regeneration, use of this parameter resulted in overestimation of the proliferative compartment when it was compared with H3 histone messenger RNA expression. Next we determined whether H3 histone messenger RNA expression could be used to study hepatocellular proliferation in archival human material. H3 histone messenger RNA-expressing hepatocytes were identified on in situ hybridization in patients with acute or chronic active hepatitis and active cirrhosis, but not inactive cirrhosis. These studies demonstrate that H3 histone messenger RNA is expressed in a phasic manner during liver regeneration. Use of H3 histone messenger RNA expression to evaluate hepatocellular proliferation should facilitate clinical studies and greatly advance our understanding of the pathophysiology of liver regeneration.

Adolescent↗
PubMed1992

Immune tolerance to a defined heterologous antigen after intrasplenic hepatocyte transplantation: implications for gene therapy.

Development of a host immune response against gene products expressed by genetically modified cells could be a serious limitation for gene therapy. During examination of whether site-specific differences in antigen presentation could regulate the host immune response, we observed an absence of antibodies against hepatitis B virus surface antigen (HBsAg) when HBsAg producing transgenic hepatocytes were transplanted into the spleen. Intrasplenic transplantation resulted in translocation of a large number of cells into the portal vascular bed and liver sinusoids. In these recipients, HBsAg secreted by the transplanted hepatocytes circulated indefinitely in the blood. In contrast, subcutaneous or intraperitoneal transplantation of the transgenic hepatocytes induced an anti-HBs response, followed by clearance of serum HBsAg. Rechallenge with HBsAg in a highly immunogenic form failed to break the tolerance in intrasplenic hepatocyte recipients even though these animals responded to another antigen (keyhole limpet hemocyanin). Immunization with HBsAg in intraperitoneal recipients of HBsAg producing hepatocytes further elevated anti-HBs titers. Our results indicate that hepatocyte transplantation into the portal vascular bed via injection into the spleen can confer immune tolerance to secreted heterologous antigens. This finding should have important implications for human gene therapy as well as for analyzing the mechanisms of immune tolerance.

Animals↗
PubMed1992

Distribution of albumin and alpha-fetoprotein mRNAs in normal, hyperplastic, and preneoplastic rat liver.

The nature of bile duct-like (oval) cells proliferating during chemical hepatocarcinogenesis has been controversial. To investigate this issue further, the authors compared the hepatic distribution of albumin (ALB) and alpha-fetoprotein (AFP) mRNAs in rats in which oval cell proliferation was induced by feeding a choline-devoid diet containing 0.1% ethionine (CDE, a hepatocarcinogenic diet) with that in normal rats and in rats in which biliary epithelial cell hyperplasia was induced by either bile duct ligation or feeding alpha-naphthylisothiocyanate (ANIT). Northern blot analysis in parenchymal and nonparenchymal liver cells isolated from these animals demonstrated that ALB mRNA was present in the hepatocytes of both control and experimental animals, whereas this transcript was detected in nonparenchymal epithelial cells only in CDE-fed rats. Alpha-fetoprotein mRNA was not seen in either parenchymal or nonparenchymal cells isolated from normal or hyperplastic livers induced by bile duct ligation or ANIT feeding. In CDE-fed rats, however, both parenchymal and nonparenchymal cell populations displayed AFP message. In situ hybridization directly demonstrated nonparenchymal cell expression of both ALB and AFP transcripts in CDE-fed rats. Most surprisingly, ALB and AFP mRNAs were also detected by in situ hybridization in occasional nonparenchymal cells located in portal tracts near the limiting plate in normal liver, as well as under conditions associated with bile duct hyperplasia. Immunohistochemical studies of intermediate filament proteins, cytokeratin 19 (a marker of glandular epithelia), vimentin (a marker of mesenchymal lineage), and desmin (a marker of muscle cell differentiation) demonstrated that oval cells, as well as normal and hyperplastic bile duct cells, were positive for cytokeratin 19 and negative for both vimentin and desmin. Cytokeratin-positive oval cells formed duct profiles and were connected to preexisting ductules and ducts. These results are construed to suggest that oval cells proliferating during CDE hepatocarcinogenesis are derived from epithelial cells within the biliary tree. The presence of cells with similar morphologic appearance, periportal location, and AFP and ALB expression in normal liver suggests that these cells may be the progenitors of oval cells induced by some carcinogenic regimens.

Animals↗
PubMed1991

Permanent engraftment and function of hepatocytes delivered to the liver: implications for gene therapy and liver repopulation.

To examine the distribution of intrasplenically transplanted hepatocytes, we used HBsAg-producing G7 HBV transgenic hepatocytes or cells labeled with 111In. Most hepatocytes translocated to the liver (55% +/- 7%; mean +/- S.D.); the spleen retained a smaller fraction (15% +/- 3%); and some transplanted cells localized in lungs (3%) or pancreas (1%). Transplanted hepatocytes were rapidly assimilated into the liver lobule. Morphometrical quantitation indicated that the numbers of transplanted hepatocytes in the liver at 48 hr and at 9 mo after transplantation were similar. Serum HBsAg was detected in recipients of the G7 HBV hepatocytes during the 1-yr experiment. These results indicate that a large number of hepatocytes can be reproducibly delivered to the liver by transplantation into the spleen. Transplanted hepatocytes engraft rapidly, assimilate into host liver, maintain normal function and survive permanently. Systems for safe delivery and localization of hepatocytes in the liver represent a critical step toward successfully accomplishing hepatocyte-directed gene therapy and repopulation of the acutely devastated liver.

Animals↗
PubMed1991

Expression of leukocyte adhesion molecules in the liver of patients with chronic hepatitis B virus infection.

Virus-specific T-cell responses are believed to be involved in the pathogenesis of liver cell injury secondary to hepatitis B virus infection. In this study, liver biopsy specimens from patients with chronic hepatitis B virus infection were analyzed for expression of two major pathways of adhesion used by cytotoxic T cells to interact with target cells. The lymphocyte function-associated antigen 3 was found preferentially expressed on hepatocytes of patients with active hepatitis B virus replication, whereas the expression of the intercellular adhesion molecule 1 on hepatocytes seemed more closely related with inflammatory activity. Adhesion molecules were also highly expressed on T lymphocytes found in areas of piecemeal and spotty necrosis, indicating the presence of antigen-specific "memory" T cells at the site of hepatocellular injury. This study suggests that the expression of the lymphocyte function-associated antigen 3 on hepatocytes may be important for viral elimination. The coordinate expression of the intercellular adhesion molecule 1 may regulate inflammatory response and enhance viral antigen presentation to T cells. Conversely, the absence of hepatocyte adhesion molecules might be a favorable factor for viral persistence.

Antigens, Surface↗
PubMed1991

Thymosin treatment of chronic hepatitis B: a placebo-controlled pilot trial.

Chronic hepatitis B is a severe and frequently progressive disease. We assessed the safety and efficacy of thymosin fraction 5 and thymosin-alpha 1 in a prospective, placebo-controlled trial in 12 patients with chronic hepatitis B. All patients had histological and biochemical evidence of active liver disease for at least 6 mo before treatment and were positive for serum hepatitis B virus DNA and HBsAg. Seven patients received thymosin fraction 5 or thymosin-alpha 1 and five patients received placebo twice weekly for 6 mo. By the conclusion of the study (1 yr), serum aminotransferase levels had improved significantly in thymosin-treated patients, but not in the placebo group. Six (86%) of the thymosin treated patients and one (20%) patient given placebo cleared hepatitis B virus DNA from serum (p less than 0.04, Fisher's exact test). After treatment, replicative forms of hepatitis B virus DNA were present in the liver specimens of four of five placebo-treated patients but in only one of seven thymosin-treated patients (p less than 0.04, Fisher's exact test). Response to thymosin therapy was associated with significant improvements in peripheral blood lymphocyte and CD3 and CD4 counts and in in vitro production of interferon-gamma over initial values. No significant side effects were observed in patients given thymosin or in placebo-treated patients. Clinical, biochemical and serological improvement in patients responding to thymosin were sustained during 26 +/- 3 mo of follow-up. The results of this pilot trial suggest that thymosin therapy promotes disease remission and cessation of hepatitis B virus replication in patients with chronic viral infection.

Adolescent↗
PubMed1990

A novel system for transplantation of isolated hepatocytes utilizing HBsAg-producing transgenic donor cells.

Hepatocytes from donor transgenic mice that produce an easily assayable circulating marker have been used to develop a novel hepatocyte transplantation system. Isolated G7 HBV transgenic donor hepatocytes secreting HBsAg were transplanted into congeneic or allogeneic mouse recipients. Serum HBsAg was present three days after hepatocyte transplantation in congeneic animals and persisted indefinitely when hepatocytes were transplanted into the spleen. Transplanted hepatocytes within the splenic pulp were identified by morphologic and histochemical analysis. Migration of hepatocytes injected into the spleen to the liver was demonstrated by in situ hybridization using an RNA probe for HBsAg. Transplantation into nonimmunosuppressed allogeneic recipients resulted in disappearance of detectable hepatocytes in the spleen within two weeks. This novel transplantation system should facilitate studies of hepatocyte engraftment and survival, modulation of allograft rejection, and development of hepatocyte-directed gene therapy.

Animals↗
PubMed1988

IgM anti-HBc in acute and chronic hepatitis B virus (HBV) infection: diagnostic value and correlation with viral replication and disease activity.

IgM antibody to hepatitis B core antigen (IgM anti-HBc) was determined in 348 subjects with hepatitis B virus infection, in order to evaluate, in an area of high hepatitis D virus (HDV) endemicity, its usefulness in discriminating acute HBV hepatitis from HDV superinfection of HBsAg carriers, and to see whether in chronic HBV infection IgM anti-HBc can be related to viral replication, disease activity, or risk of neoplastic transformation. The positive predictive value (PV) of IgM anti-HBc for acute hepatitis was low at the standard 2.1 cut-off (35.2%), but a cut-off of 7 raised the positive PV, retaining a negative PV of above 90% and a sensitivity of 59.5%. No significant relationship was found in chronic infection between IgM anti-HBc, the level of HBV replication or the type of liver disease. Patients with HDV infection were mostly IgM anti-HBc negative. Hepatocellular carcinoma was not associated with a raised prevalence of IgM anti-HBc.

Acute Disease↗
PubMedDate not supplied

Assessment of some risk factors for hepatocellular carcinoma: a case control study.

A case-control study of risk for hepatocellular carcinoma (HCC) was carried out in our Department from December 1980 to December 1983. One hundred and twenty consecutive inpatients with HCC were compared with 360 controls pair-matched by sex and age (within years). For each case three different controls were selected from inpatients at the same hospital: one patient with liver cirrhosis; one patient with solid tumor and one patient with chronic illness other than neoplasm or liver disease. We report here the results on alcohol consumption, smoking habit and hepatitis B virus infection. The risk factors investigated are distributed similarly in HCC and cirrhosis. The prevalence of alcohol abuse in HCC is similar to that in cirrhosis and is significantly higher than in other neoplastic or otherwise chronically ill patients (odds ratio 2 X 3 and 3 X 2 respectively). Thus alcohol abuse is probably a risk factor for HCC as a cause of cirrhosis. Smoking habits were similar among the various disease groups and independent of alcohol consumption. The prevalence of heavy smoking was comparable in cases and controls. HbsAg negative-HCC with an ultrasonographic pattern of 'diffuse' alteration was more frequent in heavy smokers.

Adult↗