RESUMO
We studied the DNA sequence of the entire coding region of ERCC1 gene, in five cell lines established from human ovarian cancer (A2780, A2780/CP70, MCAS, OVCAR-3, SK-OV-3), 29 human ovarian cancer tumor tissue specimens, one human T-lymphocyte cell line (H9), and non-malignant human ovary tissue (NHO). Samples were assayed by PCR-SSCP and DNA sequence analyses. A silent mutation at codon 118 (site for restriction endonuclease MaeII) in exon 4 of the gene was detected in MCAS, OVCAR-3 and SK-OV-3 cells, and NHO. This mutation was a C-->T transition, that codes for the same amino acid: asparagine. This transition converts a common codon usage (AAC) to an infrequent codon usage (AAT), whereas frequency of use is reduced two-fold. This base change was associated with a detectable band shift on SSCP analysis. For the 29 ovarian cancer specimens, the same base change was observed in 15 tumor samples and was associated with the same band shift in exon 4. Cells and tumor tissue specimens that did not contain the C-->T transition, did not show the band shift in exon 4. Our data suggest that this alteration at codon 118 within the ERCC1 gene, may exist in platinum-sensitive and platinum-resistant ovarian cancer tissues.
Assuntos
Proteínas de Ligação a DNA , Endonucleases , Neoplasias Ovarianas/genética , Polimorfismo Conformacional de Fita Simples , Proteínas/genética , Antineoplásicos/uso terapêutico , Asparagina , Carboplatina/uso terapêutico , Linhagem Celular , Cisplatino/uso terapêutico , DNA/análise , DNA/genética , DNA de Neoplasias/análise , DNA de Neoplasias/genética , Éxons/genética , Feminino , Genes/genética , Humanos , Dados de Sequência Molecular , Neoplasias Ovarianas/tratamento farmacológico , Ovário/química , Mutação Puntual/genética , Polimorfismo de Fragmento de Restrição , Análise de Sequência de DNA , Linfócitos T/química , Células Tumorais CultivadasRESUMO
PURPOSE: To investigate the relationship between medical students' confidence and their experiences in caring for patients within a primary care clerkship, because hands-on experience is assumed to be positively related to the development of confidence (a subjective marker of competence). METHOD: The participants were 60 students from the class of 1992 who completed a required third-year ambulatory care clerkship at the University of Kentucky Medical Center. The students documented their one-on-one experiences in patient care (under the supervision of preceptors in family practice, general pediatrics, or general internal medicine) by completing data cards on each patient encounter. Also, for each encounter, the students used a Likert scale to rate their levels of confidence in dealing with the patient's primary diagnosis. The variables recorded on the cards were then used to predict the students' levels of confidence during the encounters. The statistical analysis included descriptive statistics, Pearson correlations, and a stepwise multiple-regression procedure. RESULTS: The mean number of patient encounters per student was 99. The regression procedure selected three variables from the data cards as significant independent predictors of the students' confidence: management responsibility for the patient's problem (R2 = .40), prior exposure to the patient's problem (R2 = .08), and performance of laboratory work during the patient encounter (R2 = .06). These variables were responsible for predicting 54% of the observed variance in the students' confidence (R2 = .54). CONCLUSION: Hands-on clinical experience was more important for building students' confidence than any other encounter variable.
