Biomedical subjects

C Cassé

Publications and source records attributed to C Cassé.

5 recordsLinked to original sources

PubMed1999

The transcriptional inhibitors, actinomycin D and alpha-amanitin, activate the HIV-1 promoter and favor phosphorylation of the RNA polymerase II C-terminal domain.

Actinomycin D and alpha-amanitin are commonly used to inhibit transcription. Unexpectedly, however, the transcription of the human immunodeficiency virus (HIV-1) long terminal repeats (LTR) is shown to be activated at the level of elongation, in human and murine cells exposed to these drugs, whereas the Rous sarcoma virus LTR, the human cytomegalovirus immediate early gene (CMV), and the HSP70 promoters are repressed. Activation of the HIV LTR is independent of the NFkappaB and TAR sequences and coincides with an enhanced average phosphorylation of the C-terminal domain (CTD) from the largest subunit of RNA polymerase II. Both the HIV-1 LTR activation and the bulk CTD phosphorylation enhancement are prevented by several CTD kinase inhibitors, including 5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole. The efficacies of the various compounds to block CTD phosphorylation and transcription in vivo correlate with their capacities to inhibit the CDK9/PITALRE kinase in vitro. Hence, the positive transcription elongation factor, P-TEFb, is likely to contribute to the average CTD phosphorylation in vivo and to the activation of the HIV-1 LTR induced by actinomycin D.

Amanitins↗

PubMed1999

Regulated phosphorylation of the RNA polymerase II C-terminal domain (CTD).

The largest subunit of RNA polymerase II has an intriguing feature in its carboxyl-terminal domain (CTD) that consists of multiple repeats of an evolutionary conserved motif of seven amino acids. CTD phosphorylation plays a pivotal role in controlling mRNA synthesis and maturation. In exponentially growing cells, the phosphate turnover on the CTD is fast; it is blocked by common inhibitors of transcription, such as 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole and actinomycin D. Transcription-independent changes in CTD phosphorylation are observed at critical developmental stages, such as meiosis and early development.

Animals↗

PubMed1997

Synergism between multiple virus-induced factor-binding elements involved in the differential expression of interferon A genes.

Comparative transfection analysis of murine interferon A4 and interferon A11 promoter constructs transiently transfected in mouse L929 and human HeLa S3 cells infected with Newcastle disease virus showed that the second positive regulatory domain I-like domain (D motif), located between nucleotides -57 and -46 upstream of the transcription start site, contributes to the activation of virus-induced transcription of the interferon (IFN)-A4 gene promoter by cooperating with the positive regulatory domain I-like and TG-like domains previously described. Electrophoretic mobility shift assay performed with the virus-inducible fragments containing these motifs indicated that the binding activity that we have denoted as virus-induced factor (Génin, P., Bragança, J., Darracq, N., Doly, J., and Civas, A. (1995) Nucleic Acids Res. 23, 5055-5063) is different from interferon-stimulated gene factor 3. It binds to the D motif but not to the virus-unresponsive form of the D motif disrupted by a G-57 --> C substitution. We show that the low levels of IFN-A11 gene expression are caused essentially by the lack of two inducible enhancer domains disrupted by the A-78 --> G and the G-57 --> C substitutions. These data suggest a model taking account of the differential regulation of IFN-A gene family members. They also suggest that virus-induced factor may correspond to the primary transcription factor directly activated by virus that is involved in the initiation of IFN-A gene transcription.

Animals↗

PubMed1995

[Urethroplasty in 2 stages using skin grafts].

OBJECTIVE: To present the technique and results of 2-stage mesh-graft urethroplasty, as described by Schreiter in 1984. METHODS: 11 patients with a stricture of the anterior urethra were treated according to this urethroplasty (pedicle skin flap). The site of the stricture was penile in 4 cases and perineoscrotal in 7 cases, and the mean length was 7.7 cm (range: 3 to 12.5). RESULTS: 10 patients were treated in 2 stages, while the remaining patient has a persistent perineal urethrostomy. With a mean follow-up of 3.5 years (range: 14 to 77 months), 9 patients obtained a satisfactory result with no radiographic recurrence, but with persistent nocturia (x 2/night), a mean peak flow rate of 12.8 ml/s, and a mean residual urine of 55 ml present in 8 our of 9 cases. One complete failure was observed, following complete recurrence of the stricture due to the limited dimensions of the skin flap at the 2nd stage. CONCLUSION: This technique constitutes a useful salvage solution after failure of a one-stage urethroplasty. It can be used to treat extensive strictures of the anterior urethra by reconstituting a good quality urethral lumen with well vascularized tissue. It also has the advantage of avoiding the presence of hair follicles and allows the two stages to be performed at a brief interval.

Aged↗

PubMedDate not supplied

[Prostatic involvement in leukemia. Report of a case].

Infiltration of the prostate is frequent in the course of leukaemia. It is usually asymptomatic or may present in the form of classical bladder neck obstruction. The diagnosis is generally established during investigation of benign prostatic hypertrophy by biopsy or during treatment by resection. Treatment of leukaemia by systemic chemotherapy is unable to sterilize the prostatic site and must therefore be combined with local radiotherapy.

Aged↗