Showing papers by "Olivier Bernard published in 1991"

Two site-specific deletions and t(1;14) translocation restricted to human T-cell acute leukemias disrupt the 5' part of the tal-1 gene.

Abstract: Analysis of several cases of t(1:14)(p32;q11) translocation present in 3% of T-cell acute leukemias (T-ALL) has revealed the tal-1 gene. This gene encodes a helix-loop-helix protein. It has been found to be expressed in normal bone marrow and in leukemic T-cell and erythroleukemia cell lines, but not in normal T cells. Recently, a site-specific deletion, tald, renamed tald1 in this paper, has been detected in a high proportion of pediatric T-ALL, which arose by a site-specific DNA recombination between tal-1 and a new locus termed SIL. In this study we searched for structural rearrangements within tal-1 in a panel of 134 non-selected leukemic patients (including 66 with T-ALL). Only 6% of patients with T-ALL harbored the tald1 deletion. A second specific deletion termed tald2 was observed in another 6% of T-ALL patients; it involves another site within tal-1 plus the same site as tald1 in the SIL locus. Similarly to tald1 deletion, tald2 junctions harbor structural characteristics that are reminiscent of aberrant recombinase activity. Moreover, we report a detailed analysis of the tal-1 gene structure. Transcription analysis and in vitro translation data are consistent with the differential expression of several TAL-1 protein species containing the HLH motif but differing in their amino terminus. Taken together, our data indicate that t(1;14) translocations and both tald deletions disrupt the 5' part of the tal-1 gene, placing its entire coding sequences under the control of the regulatory elements of the TCR-delta gene or the SIL gene, both of which are normally expressed in T-cell lineage.

Diagnostic value of serum gamma-glutamyl transpeptidase activity in liver diseases in children.

Abstract: The clinical usefulness of serum gamma-glutamyl transpeptidase (gamma GT) assay for the diagnosis of liver disease in children was assessed retrospectively in 398 children investigated from 1981 to 1986, in whom diagnosis was ascertained according to currently accepted criteria including liver histology in each case. Serum gamma GT activity was within normal limits in 10 controls, in 19 children with portal vein obstruction, and in 10 of 12 children with congenital hepatic fibrosis. Serum gamma GT was raised in all children with biliary atresia, sclerosing cholangitis, paucity of interlobular bile ducts, and alpha 1-antitrypsin deficiency with jaundice. Serum gamma GT was normal in spite of patent clinical signs of cholestasis in 3 patients with benign recurrent intrahepatic cholestasis, 1 infant with post-hemolytic neonatal cholestasis, and in 22 of 28 patients with progressive idiopathic cholestasis akin to Byler disease. In the latter group, children with raised serum gamma GT displayed extensive portal fibrosis and bile duct proliferation on liver histology, while this was not a prominent feature in children with normal serum gamma GT. These results indicate (a) the value and limits of the assay for serum gamma GT activity in children with liver disease, (b) that raised serum gamma GT may be considered a fairly reliable index of bile duct damage, and (c) that serum gamma GT may prove a useful tool in separating two forms of progressive idiopathic cholestasis, with or without bile duct involvement.

Biliary complications after transplantation in children: Role of imaging modalites

Abstract: Among a series of 140 liver transplantations in children, 21 biliary complications (BC) (15%) are reported. BC were identified from 2 days to 3 months after LT. Positive US findings were present in 20 cases. Cholangiography was obtained by opacification of a surgical drain in 3 cases, per-operatively in 3 and by PTC in 15. Drainage was placed in 9 and ballon dilatation performed in 2. Causes of BC include hepatic artery (HA) thrombosis in 7, HA stenosis in 1, anastomosis stricture in 7, anastomosis kink in 3, mucocele of cystic duct remnant in 2 and sludge in 1. Treatment was surgical in all, but 2 cases were treated percutaneously. There is a great difference in severity of prognosis between complications secondary to HA thrombosis and isolated BC. Role of US in diagnosis and of PTC and interventional radiology in treatment are emphasized.

Late cholangitis after successful surgical repair of biliary atresia.

Abstract: • Bacterial cholangitis is a frequent complication of successful surgical repair of biliary atresia, occurring in 93% of patients before the age of 1 year, but thought to be rare after 2 years of age. Among 76 children free of jaundice more than 5 years after operation, four presented with late cholangitis (7 to 13.5 years old), consisting of fever, jaundice, and abdominal pain with biochemical features of an inflammatory process and cholestasis. Liver biopsy specimens consistently demonstrated histological features of cholangitis, growth of microorganisms, or both. Cholangitis subsided spontaneously in one patient or in response to intravenous administration of antibiotics. Cholangiography consistently demonstrated biliary abnormalities but no definite obstruction to the bilioenteric anastomosis. All the children had good hepatic function 3 weeks to 4 years after the episode of cholangitis. These results suggest that cholangitis may occur several years after surgery but does not seem to alter prognosis. ( AJDC . 1991;145:213-215)

Inactivation of the p53 gene expression by a splice donor site mutation in a human T-cell leukemia cell line.

Abstract: An abnormally sized 3.5 kb p53 transcript was detected in the KE-37R human leukemic T-cell line in which no p53 protein could be detected by immunoprecipitation. S1 nuclease protection experiments and sequencing analysis indicated conservation of the entire intron 4 (755 bp) in the 3.5 kb transcript and the presence of a G to A substitution in the last exonic nucleotide of the splice donor site. These data support the notion that p53 gene inactivation by point mutations in splice junctions also exists in hemopoietic neoplasia.

c-myc gene expression in a leukemic T-cell line bearing a t(8;14) (q24;q11) translocation.

Abstract: We have examined the expression of the c-myc protooncogene in human T-cell leukemic KE-37R cells carrying a t(8;14) (q24;q11) translocation. The breakpoint on chromosome 8 is located at 2.2 kb downstream of c-myc exon 3 and the 3' part of the TcR-alpha gene (14q11) has been juxtaposed to c-myc. Our results showed that the steady-state levels of c-myc RNA transcripts were increased and the P1/P2 ratio of c-myc promoter utilization did not change, indicating that preferential utilization of P2 was maintained in the rearranged gene. High levels of electrophoretically normal p64 and 67 c-myc proteins were detected and both products kept their instability. In addition, transcription from promoter P0 was not detectable. Our results suggest that the activation of the gene is likely to result from its juxtaposition to the enhancer element of the TcR-alpha gene located downstream of the Ca region which stimulates constitutive synthesis of normal c-myc transcripts from the rearranged allele.