Screening for occult nodal metastasis in squamous cell carcinoma of the vulva.

Metastases to inguinofemoral lymph nodes in patients with carcinoma of the vulva alter the prognosis and treatment of this disease. Our goal was to determine if immunohistochemical staining could reveal occult metastatic nodal disease not detected with routine hematoxylin and eosin staining. We retrospectively examined a total of 110 lymph nodes from 10 patients who had undergone lymph node dissection and found to have all negative nodes. Paraffin embedded lymph nodes were immunostained with a monoclonal antibody directed against multiple low- and high-molecular weight cytokeratins. Micrometastases were not detected in any lymph nodes examined with immunohistochemistry. All positive and negative controls yielded satisfactory results. It is concluded that immunohistochemistry with cytokeratin antibodies does not provide greater sensitivity than routine hematoxylin and eosin staining for the detection of nodal metastases in vulvar carcinoma.

A genetic screen for temperature-sensitive cell-division mutants of Caenorhabditis elegans.

A novel screen to isolate conditional cell-division mutants in Caenorhabditis elegans has been developed. The screen is based on the phenotypes associated with existing cell-division mutations: some disrupt postembryonic divisions and affect formation of the gonad and ventral nerve cord-resulting in sterile, uncoordinated animals-while others affect embryonic divisions and result in lethality. We obtained 19 conditional mutants that displayed these phenotypes when shifted to the restrictive temperature at the appropriate developmental stage. Eighteen of these mutations have been mapped; 17 proved to be single alleles of newly identified genes, while 1 proved to be an allele of a previously identified gene. Genetic tests on the embryonic lethal phenotypes indicated that for 13 genes, embryogenesis required maternal expression, while for 6, zygotic expression could suffice. In all cases, maternal expression of wild-type activity was found to be largely sufficient for embryogenesis. Cytological analysis revealed that 10 mutants possessed embryonic cell-division defects, including failure to properly segregate DNA, failure to assemble a mitotic spindle, late cytokinesis defects, prolonged cell cycles, and improperly oriented mitotic spindles. We conclude that this approach can be used to identify mutations that affect various aspects of the cell-division cycle.