Lower phenytoin serum levels in persons switched from brand to generic phenytoin.

After generic phenytoin (PHT) was marketed, the authors identified eight adult patients (ages 34 to 49) whose seizures increased enough to require intervention after switching to generic PHT. The mean total PHT concentration on brand (before generic) was 17.7 +/- 5.3 mg/L, decreased to 12.5 +/- 2.7 mg/L with generic, and increased to 17.8 +/- 3.9 mg/L after brand was re-introduced. Brand and generic PHT do not yield equivalent concentrations in some patients and substitution should not be permitted without physician notification.

Immunohistochemical detection of c-myc protein in head and neck tumors.

OBJECTIVES: To evaluate the correlation between the levels of immunohistochemically detectable c-myc protein in squamous cell carcinoma of the head and neck and clinicopathologic prognostic variables utilized in clinical practice. DESIGN: Cohort study. SETTING: University and Veterans Administration medical centers, Cincinnati, Ohio. PATIENTS OR OTHER PARTICIPANTS: Consecutive samples. INTERVENTION: Surgery for squamous cell carcinoma of the head and neck. MAIN OUTCOME MEASURE: Correlation between c-myc expression and tumor size, nodal involvement, clinical disease stage, and degree of differentiation. Hypothesis formulated after data collection. RESULTS: Significant negative correlation between the c-myc levels and the number of metastatic nodes (P = .0001) and clinical stage of disease (P = .05). No correlation with tumor size or degree of differentiation. CONCLUSIONS: Reduction or loss of c-myc oncoprotein might be associated with metastatic lymph node involvement and advanced stages of squamous cell carcinoma of the head and neck. Further studies are needed to substantiate preliminary findings.

Relationship between immunohistochemically detectable p53 protein and prognostic factors in head and neck tumors.

This study examined the relationship between immunohistochemically detectable p53 protein and prognostic factors in squamous cell carcinoma of the head and neck (SCCHN). Twenty-seven tumor specimens were evaluated utilizing a panel of three monoclonal antibodies (MAbs) directed against different epitopes of the p53 protein (PAb 421, PAb 1801, and PAb 240). The overall incidence of p53 protein detection with a panel of MAbs was 78%, which was significantly higher than with any one of the tested antibodies. Comparison of the tumors that were negative for p53 with tumors that stained positive with one or multiple antibodies, however, revealed no statistically significant differences with respect to the stage of disease, metastatic node involvement, size of the primary tumor, or degree of tumor differentiation. The results of our study suggest that levels of p53 protein, although commonly immunohistochemically detected in head and neck tumors, do not correlate with known prognostic factors for SCCHN.

High c-myc protein expression in benign colorectal lesions correlates with the degree of dysplasia.

Sections of normal colon (n = 14), hyperplastic polyps (n = 31) ulcerative colitis (n = 97) and tubular adenomas (n = 40) were examined by immunohistochemistry for the expression of the c-myc proto-oncogene product in order to assess its potential diagnostic value in predicting the malignant potential of these lesions. We compared the degree of epithelial abnormality in these colorectal specimens with the extent of immunoperoxidase staining for c-myc oncoprotein, we found that high c-myc protein expression correlated with the degree of epithelial alteration in ulcerative colitis and tubular adenoma groups. Weakly positive staining was found in 10 out of 14 normal colon samples and 28 out of 31 hyperplastic polyps. High tissue expression of c-myc protein, when combined with histologic dysplasia, may prove to be an additional factor in the evaluation of malignant potential in ulcerative colitis specimens and adenomas.