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A Dejean

Publications and source records attributed to A Dejean.

78 records · Page 5Linked to original sources
PubMed1982

Organization and expression of hepatitis B sequences cloned from hepatocellular carcinoma tissue DNA.

We have constructed a phage lambda library of liver DNA fragments from West African patient who died of liver failure due to advanced hepatocellular carcinoma. Four hepatitis B virus (HBV) DNA-carrying recombinants have been isolated, one clone (lambda IA22) being analyzed in greatest detail. It contains approximately 3.8 kb of HBV DNA without detectable deletions or rearrangements. One site of integration lies close to the nick in free viral DNA. The restriction map of the HBV sequences is close to those published for the ay subtype. Coconvection of mouse Ltk- cells with lambda IA22 and cloned thymidine kinase gene results in the expression of gene S and the excretion of hepatitis B surface antigen (HBsAg) particles into the culture supernatant.

Base Sequence↗
PubMedDate not supplied

Comparative effect of the venoms of ants of the genus Pachycondyla (Hymenoptera: Ponerinae).

The venoms of 12 Pachycondyla ant species, all generalist predators, were compared for their paralytic and lethal effects during prey capture of the cricket, Acheta domesticus. The observed values covered a wide range that seems surprising when considering the close phylogenetic relatedness of the species. Although employed for different purposes, these venoms had the same type of physiological effect. They caused a rapid, dose-dependent and reversible paralysis, followed by a second slow-acting paralysis which was permanent when complete and led to death in less than 4 days. This finding suggests the existence of similar toxins and of both neurotoxins and histolytic compounds as necrosis were often observed in dead animals. Comparisons based on the nesting habitats of the species highlighted significant differences in paralysis after 2 h and lethality with arboreal species' venoms more efficacious than those of ground-dwelling species, thanks to their higher potency and their rather fast-acting effect. Such a tendency may be considered as an adaptation to arboreal life as the possibilities of escape for the prey are more numerous than on the ground or in the leaf litter.

Animals↗
PubMedDate not supplied

The hepatitis B virus.

DNA recombinant technology has radically changed hepatitis B virus (HBV) virology. The genetic organization, transcription and replication of the virus are basically understood, structures of integrated HBV sequences in hepatocellular carcinoma have been characterized, and new vaccines produced by recombinant DNA technique are being developed.

Amino Acid Sequence↗
PubMedDate not supplied

Hepatitis B virus DNA integration in a sequence homologous to v-erb-A and steroid receptor genes in a hepatocellular carcinoma.

Hepatitis B virus (HBV) is clearly involved in the aetiology of human hepatocellular carcinoma (HCC) and the finding of HBV DNA integration into human liver DNA in almost all HCCs studied suggested that these integrated viral sequences may be involved in liver oncogenesis. Several HBV integrations in different HCCs and HCC-derived cell lines have been analysed after molecular cloning without revealing any obvious role for HBV. From a comparison of a HBV integration site present in a particular HCC with the corresponding unoccupied site in the non-tumorous tissue of the same liver, we now report that HBV integration places the viral sequence next to a liver cell sequence which bears a striking resemblance to both an oncogene (v-erb-A) and the supposed DNA-binding domain of the human glucocorticoid receptor and human oestrogen receptor genes. We suggest that this gene, usually silent or transcribed at a very low level in normal hepatocytes, becomes inappropriately expressed as a consequence of HBV integration, thus contributing to the cell transformation.

Amino Acid Sequence↗
PubMedDate not supplied

A novel steroid thyroid hormone receptor-related gene inappropriately expressed in human hepatocellular carcinoma.

We have previously isolated from a human hepatocellular carcinoma a hepatitis B virus integration in a 147-base-pair cellular DNA fragment, similar to steroid- and c-erb-A/thyroid-hormone receptor genes. We have now cloned the corresponding complementary DNA from a human-liver cDNA library. Nucleotide sequence analysis revealed that the overall structure of the cellular gene, which we have named hap, is similar to that of the DNA-binding hormone receptors. That is, it displays two highly conserved regions identified as the putative DNA-binding and hormone-binding domains of the c-erb A/steroid receptors. Six out of seven hepatoma and hepatoma-derived cell-lines express a 2.5-kilobase (kb) hap messenger RNA species which is undetectable in normal adult and fetal livers but present in all non-hepatic tissues analysed. The data suggest that the hap gene product may be a novel ligand-responsive regulatory protein whose inappropriate expression in liver may relate to the hepatocellular carcinogenesis.

Amino Acid Sequence↗