Immunophenotypic analysis of ovarian and testicular Müllerian papillary serous tumors.

Intratesticular Müllerian papillary serous tumors lacking stromal invasion are uncommon neoplasms whose immunophenotypic properties have not been studied extensively. We present such information here and compare it with information from a group of ovarian papillary serous tumors of low malignant potential ("borderline serous tumors") that are morphologically identical. We compared the histologic features of our index case of intratesticular Müllerian papillary serous tumor with those of nine ovarian papillary serous tumors. We then evaluated both the index case and the ovarian tumors with antibodies against carcinoembryonic antigen, LeuM1, CA125, estrogen receptors, progesterone receptors, cytokeratin 7, and cytokeratin 20, by use of established immunohistochemical techniques. The testicular and ovarian tumors were morphologically indistinguishable. The intratesticular Müllerian papillary serous tumor expressed LeuM1, CA125, estrogen receptors, progesterone receptors, cytokeratin 7, and weak cytokeratin 20; carcinoembryonic antigen was not expressed. All of the ovarian papillary serous tumors expressed CA125, estrogen receptors, and cytokeratin 7. Eight of nine expressed progesterone receptors. Five of nine stained with LeuM1. Two of nine were focally weakly positive with cytokeratin 20. LeuM1 expression helps distinguish testicular papillary serous tumors from mesothelial proliferations, which might seem morphologically similar. The immunophenotype of intratesticular and female genital papillary serous tumors is similar; this similarity extends to expression of estrogen and progesterone receptors, which is rare in neoplasms in men, especially among testicular neoplasms.

Enhanced catalysis by active-site mutagenesis at aspartic acid 153 in Escherichia coli alkaline phosphatase.

Bacterial alkaline phosphatase catalyzes the hydrolysis and transphosphorylation of phosphate monoesters. Site-directed mutagenesis was used to change the active-site residue Asp-153 to Ala and Asn. In the wild-type enzyme Asp-153 forms a second-sphere complex with Mg2+. The activity of mutant enzymes D153N and D153A is dependent on the inclusion of Mg2+ in the assay buffer. The steady-state kinetic parameters of the D153N mutant display small enhancements, relative to wild type, in buffers containing 10 mM Mg2+. In contrast, the D153A mutation gives rise to a 6.3-fold increase in kcat, a 13.7-fold increase in kcat/Km (50 mM Tris, pH 8), and a 159-fold increase in Ki for Pi (1 M Tris, pH 8). In addition, the activity of D153A increases 25-fold as the pH is increased from 7 to 9. D153A hydrolyzes substrates with widely differing pKa's of their phenolic leaving groups (PNPP and DNPP), at similar rates. As with wild type, the rate-determining step takes place after the initial nucleophilic displacement (k2). The increase in kcat for the D153A mutant indicates that the rate of release of phosphate from the enzyme product complex (k4) has been enhanced.