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Biomedical subjects

E Tabor

Publications and source records attributed to E Tabor.

At least 19 recordsLinked to original sources
PubMed2003

Molecular and serological aspects of HBsAg-negative hepatitis B virus infections in North America.

A few hepatitis B virus (HBV) infections are characterized by the presence of HBV DNA in serum or liver tissue, or both, in the absence of detectable hepatitis B surface antigen (HBsAg) in serum. However, such infections have rarely been described previously in North American patients. In the present study, 31 hepatocellular carcinoma (HCC) patients from the United States and Canada who had no detectable HBsAg in their serum were studied. In these 31 HBsAg-negative HCC patients, HBV DNA was detected in HCC and/or in adjacent nontumorous liver tissue using nested polymerase chain reaction (PCR) in 5/9 (56%) patients from the United States and in 12/22 (55%) from Canada. The 17 HBV DNA-positive/HBsAg-negative patients from the United States and Canada included 9 without any serological markers for HBV and 8 with detectable antibodies to hepatitis B core antigen. In these patients, HBV genotype C was the most prevalent genotype (11/17; 64%). HBV genotypes have not been previously reported in HCC patients from North America. Replicative intermediate forms of HBV (covalently closed circular HBV DNA) were detected in 2/17 (12%) HBV DNA-positive/HBsAg-negative patients, indicating that at least two of these patients had actively replicating HBV infections. The use of tests to detect HBV DNA permitted the identification of HBV infections in HBsAg-negative HCC patients from North America. Among these patients, those with antibody to hepatitis C virus (HCV) would otherwise have been designated "HCV-associated HCCs" based on serological tests alone. These findings provide a new perspective on determining the possible viral etiologies of HCCs in North America.

Amino Acid Sequence↗
PubMed2003

Interferon for preventing and treating hepatocellular carcinoma associated with the hepatitis B and C viruses.

The possibility that interferon-alpha might be effective for the prevention or treatment of hepatocellular carcinoma is suggested by its efficacy against the associated hepatitis B and C viruses, by its efficacy in the treatment of some other human tumours, and by evidence that interferon-alpha may inhibit the growth of human hepatocellular carcinoma cell lines and their production of hepatitis B surface antigen. Few studies support the use of interferon-alpha for preventing hepatitis B virus-associated hepatocellular carcinoma. In contrast, benefit from the use of interferon-alpha to prevent hepatitis C virus-associated hepatocellular carcinoma is suggested in a large number of studies, but most of these studies have weaknesses of study design that preclude definitive conclusions. Nevertheless, most of these studies suggest that the incidence of hepatocellular carcinoma is lower in hepatitis C virus-infected patients receiving interferon-alpha, particularly in patients with a sustained response to interferon-alpha, compared to nonresponders. As a treatment for hepatocellular carcinoma, interferon-alpha was only evaluated in a small number of patients with advanced disease; 'partial responses' and prolongation of survival times in a few of these studies suggest that additional studies should be done in patients with less advanced disease.

Carcinoma, Hepatocellular↗
PubMed2002

Incident hepatitis C virus infection in a community-based population in Japan.

Hepatitis C virus (HCV) is an important cause of liver disease throughout the world. However, the natural history and pathogenesis of this infection is still not completely understood. The aim of this study was to characterize the evolution of incident, asymptomatic HCV infection in a community-based population in Japan. The Miyazaki Cohort Study is a prospective study of adult residents in two villages, one of which has a very high prevalence of HCV. Nine hundred and seventy-three people from this village were enrolled in the cohort between 1984 and 1995, with antibodies to HCV (anti-HCV) found in 23%. During subsequent visits to annual health screens, new HCV seroconverters were identified among susceptible individuals, and their sequential samples were tested for anti-HCV, HCV-RNA, and HCV core antigen. Fourteen participants (six males, eight females) acquired anti-HCV during the first 11 years of study follow-up, at an incidence rate of 362 per 100 000 person-years. Detectable HCV-RNA and high anti-HCV titres (> 1:2048) were observed for more than 5 years following seroconversion in 80% (8/10) of seroconverters with sufficient information, indicating the development of persistent infection in these subjects. Three (37.5%) of the eight sero converters with persistent infection had fairly consistent, albeit mild, alanine aminotransferase elevations (30-130 IU/L) during the study. Anti-HCV seroconversions occurred at a very high rate in this community-based population in Japan, in which this infection is endemic. Persistence also developed at a high frequency among the cases of newly acquired infection, although the associated liver enzyme abnormalities were mild.

Adult↗
PubMed2001

Assessment of markers of hepatitis C virus infection in a Japanese adult population.

Latent-class analysis was used to evaluate the usefulness of markers of hepatitis C virus (HCV) infection in characterizing the true, underlying infection in a community-based Japanese population. Antibodies to HCV were detected in 24%, HCV RNA in 22%, and HCV core protein in 19% of stored serum samples from 372 adults. A 2-class model suggested that positive results for any 2 virus markers defined the current HCV infection class, with an estimated prevalence of 22% (95% confidence interval, 18%-26%). The sensitivity for detection of current HCV infection was highest for anti-HCV (97%) and was more moderate for HCV RNA (91%) and HCV core protein (85%). The specificity for each marker was > or =96%. In general, the association between demographic factors and current HCV infection status was strengthened by use of latent-class analysis that combined data for markers of HCV infection, when compared with results of logistic regression analysis for each marker separately.

Agglutination Tests↗
PubMed1999

Absence of human T-lymphotropic virus type I tax sequences in a population of normal blood donors in the Baltimore, MD/Washington, DC, area: results from a multicenter study.

BACKGROUND: It was reported recently that sequences corresponding to the human T-lymphotropic virus type I (HTLV-I) tax gene were detected in peripheral blood mononuclear cells from 8 to 11 percent of healthy blood donors without detectable antibodies to HTLV-I. A multicenter blind study was conducted to determine if these results could be independently confirmed. STUDY DESIGN AND METHODS: Specimens were collected from 100 anti-HTLV-I-negative healthy blood donors and from 11 anti-HTLV-I- or anti-HTLV-II-positive individuals. All samples were coded and distributed to each of four independent testing laboratories for polymerase chain reaction analysis to detect sequences of the HTLV-I or HTLV-II tax gene, using detailed procedures specified by the laboratory reporting the original observation. Each laboratory also tested a dilution panel of a plasmid containing HTLV-I tax to determine the analytical sensitivity of the procedure. RESULTS: The analytical sensitivity of the screening methods permitted detection of as few as 1 to 10 copies of the tax gene. However, HTLV-I tax sequences could not be detected in any of the anti-HTLV-I-negative blood donors at more than one test site. CONCLUSION: HTLV-I tax sequences appear not to be present in this population of 100 blood donors negative for anti-HTLV-I.

Adult↗
PubMed1999

Vascularization of small hepatocellular carcinomas: correlation with differentiation.

BACKGROUND: Hepatocellular carcinoma (HCC) is generally considered a hypervascular tumor when visualized by angiography. However, small HCCs are not always found to be hypervascular. METHODS: To evaluate this, 50 HCCs < or =3 cm in diameter were studied. The 50 tumors consisted of 16 well-differentiated HCCs, 25 moderately differentiated HCCs, and 9 that were each a mixture of well- and moderately differentiated HCC. RESULTS: The mean number of portal tracts in the well-differentiated HCCs was 34% of the number in the surrounding nontumorous liver, and few intratumoral arterioles were seen. In contrast, the mean number of portal tracts in the moderately differentiated HCCs was 0.6% of the number in the surrounding nontumorous liver, and abundant intratumoral arterioles were seen. For HCCs that contained both well-differentiated and moderately differentiated tumor, the distribution of portal tracts and intratumoral arterioles in each portion was similar to that seen in well-differentiated or moderately differentiated HCC alone, respectively. HCCs that were larger than 1.5 cm in diameter had fewer portal tracts and more intratumoral arterioles than HCCs whose diameters were < or =1.5 cm. CONCLUSIONS: As small HCCs increase in size and become increasingly dedifferentiated, the number of portal tracts apparently decreases and intratumoral arterioles develop. These findings may reflect changes in the hemodynamics as the HCC develops.

Actins↗
PubMed1999

Overexpression of multidrug resistance genes MDR1 and cMOAT in human hepatocellular carcinoma and hepatoblastoma cell lines.

Overexpression of either of the multidrug resistance genes MDR1 and MRP is associated with resistance of tumors to multiple chemotherapeutic agents. Overexpression of MDR1 has been reported in some cell lines derived from human hepatocellular carcinomas (HCC) and hepatoblastomas (HB). The human gene for cMOAT ( ), a homologue of MRP, is thought to mediate hepatobiliary excretion of organic anions and to be associated with cisplatin resistance. In this study, expression levels of MDR1 and cMOAT were examined in 9 human HCC and HB cell lines and 10 other human cancer cell lines. Overexpression of the cMOAT gene was observed in all 9 HCC and HB cell lines and 3 of 10 other cancer cell lines. Co-overexpression of the cMOAT and MDR1 genes was observed in 7 of 9 HCC and HB cell lines, but in none of the 10 other cancer cell lines. Seven of the HCC and HB cell lines that had overexpression of the cMOAT gene were shown to be highly resistant to cisplatin compared to 2 HCC cell lines with low levels of cMOAT expression. These findings suggest that overexpression of cMOAT could contribute to cisplatin resistance in HCC and HB.

Biological Transport, Active↗
PubMed1998

Microsatellite instability in human hepatocellular carcinoma: relationship to p53 abnormalities.

AIMS/BACKGROUND: Microsatellite instability was sought in 10 human hepatocellular carcinomas (HCCs) to determine whether defective DNA mismatch repair might be implicated in the multiple genetic alterations observed in the p53 tumor suppressor gene in some of these patients' tumors. METHODS: Genomic DNA from HCCs and adjacent nontumorous livers was subjected to PCR with primers for nine microsatellites, and PCR products were resolved in a denaturing gel. Microsatellite instability was defined as the presence of band shifts or additional bands for at least two microsatellite sequences in an HCC compared to the nontumorous liver tissue from the same patient. RESULTS: Microsatellite instability was detected in four of ten HCCs. Three of these four HCCs did not have p53 exon mutations. However, one HCC had microsatellite instability as well as multiple p53 exon mutations and multiple intron alterations. Four other patients with multiple p53 intron alterations in HCC (compared to their own nontumorous liver), three of whom also had a mutation in the exons, had no microsatellite instability. CONCLUSIONS: Defective DNA mismatch repair, as indicated by microsatellite instability, might have played a role in hepatocarcinogenesis in four of the ten patients, but in general it was not associated with p53 alterations. In one of the ten patients, defective DNA mismatch repair might have been the cause of multiple mutations in both the coding and intron sequences of the p53 gene.

Adolescent↗
PubMed1998

p53 overexpression in small hepatocellular carcinomas containing two different histologic grades.

There is evidence to suggest that a focus of less-differentiated hepatocellular carcinoma (HCC) may arise within a pre-existing well-differentiated HCC, eventually replacing it. In the present study, the p53 tumor suppressor gene was analyzed by immunohistochemistry in 31 hepato-cellular carcinomas (HCCs) containing two or more regions in the same nodule with different histologic grades. p53 was overexpressed in the nucleus in 13 of 31 HCCs (42%), in seven of which p53 overexpression was seen only in the less-differentiated area of the tumor. This suggests that overexpression of presumed mutant p53 may have contributed to dedifferentiation during the development of HCC.

Adult↗
PubMed1997

Deletion mutants of the hepatitis B virus X gene in human hepatocellular carcinoma.

Two patients with hepatocellular carcinoma (HCC) were identified who had substantial deletions within the hepatitis B virus (HBV) X gene from HCC tissues. In one patient, the deletion was found at nt. 382-389 (codons 128-130) of the X gene, followed by two nucleotide substitutions, a frame shift, and formation of a new stop codon. In the second patients, the deletion was found at nt. 389-396 (codons 130-132) of the X gene, followed by one nucleotide substitution, a frame shift, and formation of a new stop codon. The resulting X proteins in both cases would be truncated at the 3' end and would be 20 amino acids shorter than the full length X protein. These patients had been identified during a study of 25 HCC patients from Qidong, China in whom a 228-base region of the X gene was sequenced. No deletions were found within this X gene sequence in HCC tissues from the other 23 patients or in the 20 adjacent noncancerous liver samples available from these patients. However, the fact that these deletions encompassed codons 130 and 131, two adjacent codons where point mutations were found in 21 of the remaining 23 patients, suggests that this region may play an important role in hepatocarcinogenesis.

Adult↗