Biomedical subjects

S Drunat

Publications and source records attributed to S Drunat.

6 recordsLinked to original sources

PubMed2001

Homocysteine-induced decrease in endothelin-1 production is initiated at the extracellular level and involves oxidative products.

The increased cardiovascular risk associated with hyperhomocysteinemia has been partly related to homocysteine (Hcy)-induced endothelial cell dysfunction. However, the intra or extracellular starting point of the interaction between Hcy and endothelial cells, leading to cellular dysfunction, has not yet been identified. We investigated the effects of both intracellular and extracellular Hcy accumulation on endothelin-1 (ET-1) synthesis by cultured human endothelial cells. Incubation of cultures with methionine (1.0 mmol x L(-1)) for 2 h induced a slight increase in cellular Hcy content but no change in ET-1 production. Incubation of cells with Hcy (0.2 mmol x L(-1)) led to a significant fall in ET-1 generation, accompanied by a significant increase in cellular Hcy content. Addition of the amino-acid transport system L substrate 2-amino-2-norbornane carboxylic acid had no effect on the Hcy-induced decrease in ET-1 production but significantly inhibited the Hcy-induced increase in the cellular Hcy content. Incubation of cells with a lower Hcy concentration (0.05 mmol x L(-1)) also reduced ET-1 production without increasing the cellular Hcy content. Co-incubation with extracellular free-radical inhibitors (superoxide dismutase, catalase and mannitol) markedly reduced the effect of Hcy on ET-1 production. Thus, it is extracellular Hcy accumulation that triggers the decrease in ET-1 production by endothelial cells through oxidative products.

Antioxidants↗

PubMed2001

Quantification of TEL-AML1 transcript for minimal residual disease assessment in childhood acute lymphoblastic leukaemia.

Strategies currently used for residual disease detection in acute lymphoblastic leukaemia (ALL) rely on polymerase chain reaction (PCR) detection of immunoglobulin and T-cell receptor rearrangements. The TEL-AML1 fusion transcript, which is associated with t(12;21) (p13;q22), is found in 25% of childhood B-cell precursor ALL, and represents an interesting alternative target. We compared two methods for quantitating TEL-AML1 fusion transcripts: competitive PCR and real-time PCR. These techniques showed similar sensitivity (5 x 10(-5)) and reproducibility. Giving highly correlated results, both techniques can be conveniently used for TEL-AML1 transcript quantification. The constancy of TEL-AML1 expression was evaluated by measuring TEL-AML1 transcripts at different steps of the cell cycle, and in 21 cases of ALL at diagnosis. No major variation in TEL-AML1 expression was observed during the cell cycle or in 20/21 of the ALL patients. Residual disease was then determined after completion of induction therapy in 20 patients with a TEL-AML1-positive ALL. Seven patients out of 20 (35%) were still positive, including two patients with high level of residual blasts (close to or beyond 10(-2)). When comparison was possible, results obtained using TEL-AML1 quantification were in accordance with those obtained using T-cell receptor rearrangements analysis.

Child↗

PubMed2000

A novel variant of granular corneal dystrophy caused by association of 2 mutations in the TGFBI gene-R124L and DeltaT125-DeltaE126.

OBJECTIVE: To characterize the molecular defect in the TGFBI gene in a French family affected with an atypical granular corneal dystrophy. PATIENTS: This family comprises 9 affected individuals across 3 generations without consanguineous marriage. METHODS: Light and electron microscopy were used to examine corneal buttons from patients. Exons of the TGFBI gene were amplified by polymerase chain reaction and sequenced directly using an automated method. Restriction digestion analysis and heteroduplex screening were performed to confirm that the mutations identified were not polymorphisms. RESULTS: Round or snow-flakes-like deposits that stained red with Masson trichrome and appeared as dense, rod-shaped structures were observed in the most anterior layers of the central stroma. All patients were heterozygous for the R124L mutation and a novel mutation predicting the deletion of 2 amino acid residues-threonine (T) and glutamic acid (E)-at codons 125 and 126. CONCLUSIONS: This French family is affected with a novel variant of granular dystrophy that is caused by a molecular defect in the TGFBI gene, reported here for the first time. CLINICAL RELEVANCE: These 2 mutations cause a novel variant of granular dystrophy that is intermediate in severity between the classical and superficial variant forms. Arch Ophthalmol. 2000;118:814-818

Adult↗

PubMed2000

A new mutation (A546T) of the betaig-h3 gene responsible for a French lattice corneal dystrophy type IIIA.

PURPOSE: To characterize the betaig-h3 gene defect in a French family affected with lattice corneal dystrophy type IIIA (LCDIIIA). METHODS: Histologic examination was performed from corneal buttons of two patients. Genomic DNA was extracted from leukocytes, and exons of the betaig-h3 gene were amplified by polymerase chain reaction to be directly sequenced. RESULTS: Numerous deposits were evident in the stroma and beneath the Bowman membrane, which had all the features of amyloid deposits. Analysis of exon 12 revealed a heterozygous G to A transition on codon 546. CONCLUSION: In contrast to Japanese patients, these French patients affected with LCDIIIA carry a distinct mutation of the betaig-h3 gene (A546T instead of P501T). Therefore, it is unclear whether different mutations could result in the same dystrophy or whether we are dealing with clinical heterogeneity of LCDIIIA.

Adult↗

PubMed2000

Clinical, histologic, and ultrastructural features of the corneal dystrophy caused by the R124L mutation of the BIGH3 gene.

OBJECTIVE: This study was designed to describe the clinical, histologic, and ultrastructural features of the corneal dystrophy associated with the R124L mutation of the BIGH3 gene. DESIGN: Retrospective clinical and histologic review of a new genetic mutation. PARTICIPANTS: Thirty-four patients from five unrelated French families with corneal dystrophy caused by the R124L mutation of the BIGH3 gene were studied at the clinical, histologic, and ultrastructural levels. Records of patients carrying this mutation were compared with those from three unrelated patients with corneal dystrophy of Bowman's layer (CDB) type 2 (R555Q mutation) and from three unrelated patients with classic corneal granular dystrophy (R555W mutation). INTERVENTION: The mutational genetic status of the BIGH3 gene was determined for each patient, and the histologic and ultrastructural data available after corneal graft were analyzed. MAIN OUTCOMES MEASURES: Genomic DNA was extracted from peripheral blood leukocytes. Exons 4 and 12 of the BIGH3 gene were amplified by the polymerase chain reaction (PCR), and the PCR products were directly sequenced. RESULTS: All 34 patients with the R124L mutation displayed the clinical, histologic, and electron microscopic features of the dystrophy previously described as a superficial variant of corneal granular dystrophy. Combining molecular genetics with clinical and histologic findings established a clear distinction between the R555Q and R555W dystrophies. CONCLUSIONS: The R124L mutation of the BIGH3 gene is associated with specific clinical and morphologic criteria. This indicates that molecular studies are needed for an adequate classification of corneal dystrophies. All criteria are presently available to segregate the dystrophy caused by the R124L mutation (known as CDB1) from the dystrophy caused by the R555Q mutation (known as CDB2).

Adult↗

PubMed2000

Refinement of the 6q chromosomal region implicated in transient neonatal diabetes.

Transient neonatal diabetes mellitus (TNDM) is estimated to occur in approximately 1 in 500,000 births and represents 50-60% of cases of neonatal diabetes. The pattern of inheritance of TNDM and its association with chromosome 6 uniparental disomy is consistent with the presence on chromosome 6 of an imprinted gene involved in pancreatic beta-cell development. Systematic screening for chromosome 6 abnormalities in nine families with 13 individuals affected by TNDM revealed paternal isodisomy of chromosome 6 in one child and paternally derived trisomy of the chromosomal region 6q in six children from three unrelated families. To delineate more accurately the region suspected of harboring the gene of interest, precise mapping of the duplicated area was performed in children exhibiting partial 6q trisomy by using microsatellite markers. The smallest region of duplication observed in our patients was flanked by markers D6S308 and D6S1010, which are separated by <1 cM. These findings confirm that TNDM may result from the overexpression of a gene located on chromosome 6q that is exclusively expressed from the paternal allele at least during some periods of life and further refine the localization of this gene.

Aneuploidy↗