Biomedical subjects
A Vilalta
Publications and source records attributed to A Vilalta.
Induction of Drosophila RNA polymerase III gene expression by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) is mediated by transcription factor IIIB.
We have previously found that the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) induces specific transcription of tRNA and 5S RNA genes in Drosophila Schneider S-2 cells (M. Garber, S. Panchanathan, R. F. Fan, and D. L. Johnson, J. Biol. Chem. 266:20598-20601, 1991). Having derived cellular extracts from TPA-treated cells, that are capable of reproducing this stimulation in vitro, we have examined the mechanism for this regulatory event. Using conditions that limit reinitiation and produce single rounds of transcription from active gene complexes, we find that the number of functional transcription complexes is increased in extracts prepared from TPA-induced cells. We have analyzed the activities of the transcription factors TFIIIB and TFIIIC derived from extracts prepared from TPA-induced and noninduced cells. Examination of the relative activities of TFIIIC showed that both its ability to reconstitute transcription with TFIIIB and RNA polymerase III and its ability to stably bind to the DNA template are unchanged. However, the activity of TFIIIB derived from the TPA-induced cells is substantially increased compared with that derived from the noninduced cells. The differences in TFIIIB activity account for the differences in the overall transcriptional activities observed in the unfractionated extracts. Western blot analysis of the TATA-binding protein subunit of TFIIIB revealed that there is an increase in the amount of this polypeptide present in the induced cell extracts and TFIIIB fraction. Together, these results indicate that the TPA response in Drosophila cells stimulates specific transcription of RNA polymerase III genes by increasing the activity of the limiting transcription component, TFIIIB, and thereby increasing the number of functional transcription complexes.
Cloning, sequencing and expression of a cDNA encoding mammalian valyl-tRNA synthetase.
A fragment of the cDNA encoding a rat valyl-tRNA synthetase (TrsVal)-like protein was cloned from a rat cDNA library in lambda gt11 using an oligodeoxyribonucleotide (oligo) probe. Three independent plaque clones containing the human TrsVal cDNA were then isolated from a lambda gt10 human erythroleukemia cDNA library using the rat cDNA fragment as the hybridization probe. Sequence analyses of the cDNA fragments provided a 3.2-kb sequence with an open reading frame that contained the 'HIGH' synthetase signature sequence and the tRNA 3'-end-binding motif, KMSKS, and putative Val-binding motif, EWCISRQ. The sequence was extended to the 3' end of the cDNA by the polymerase chain reaction using an internal primer and an oligo(dT) adapter. The deduced 1051-amino-acid sequence shares 65% identity with yeast TrsVal, and contains a highly basic N-terminal region, a newly evolved protease-sensitive region in sequence close to the C terminus, and several sites for protein kinase C phosphorylation. A 3-kb cDNA fragment was sub-cloned into plasmid pSVL and expressed in COS-7 cells; up to a sevenfold increase in TrsVal activity was obtained. These results confirm the cloning and sequencing of a human TrsVal-encoding cDNA.
Case report: squamous cell carcinoma of the nail bed.
Explore the source record for details and available documents.
Adjuvant treatment in stage I and II malignant melanoma: a randomized trial between chemoimmunotherapy and immunotherapy.
A randomized trial comparing chemoimmunotherapy (bacillus Calmette-Guérin + chemotherapy) and immunotherapy (bacillus Calmette-Guérin alone) was carried out in high-risk stage I and II malignant melanoma patients. Eight-two evaluable patients were included. The follow-up median duration was 11 years. Recurrent melanoma developed in 28 patients (34%). The overall survival rate was 76% at 5 years and 65% at 10 years. There were no statistical differences in survival probability or disease-free survival (DFS) probability between the two treatment groups. Survival and DFS were also analyzed in relation to various prognostic factors. Statistically significant differences were only seen in a subset of 33 patients with lower limb malignant melanoma, the prognosis being better for the chemoimmunotherapy group in this location. Because of the small number of patients in each group, a week positive effect of either of these two treatments cannot be ruled out. Chemoimmunotherapy only seems to improve the prognosis of stage I or II malignant melanoma of the legs.
Nail alterations in systemic amyloidosis: report of one case, with histologic study.
Explore the source record for details and available documents.
[Peri- and subungual keratoacanthoma].
Explore the source record for details and available documents.
Free laminar thin band graft--a surgical therapeutic variant in the treatment of leg ulcers.
For the past 2 years, we have been using a surgical technique for the treatment of leg ulcers caused by chronic venous insufficiency. This consists of a type of graft biologically and technically intermediate between Reverdin and Thiersh's types. We have named it the "free laminar thin band graft." In contrast to the Thiersh graft, this simple surgical technique requires little equipment, and it can be done quickly and easily as an office procedure, with little risk to the patient. In addition, it is a low cost procedure. In our experience with this technique, healing time is shorter and lesions recur later than with the Reverdin graft. The authors describe the surgical method and report a clinical case.
[Surgical treatment of melanoma of the extremities].
Explore the source record for details and available documents.