Massive pneumatosis intestinalis: CT diagnosis.

Pneumatosis cystoides intestinalis is a rare condition characterized by multiple subserosal or submucosal gas filled cysts within the wall of a segment of bowel. It is associated with numerous conditions, both intra and extraabdominal in nature. The condition may be asymptomatic or may present clinically as nausea, vomiting, diarrhea or other signs of intestinal obstruction. With rupture of the cysts, pneumoperitoneum may be a finding. In a patient with vague clinical presentation, this finding radiographically may lead to a clinical dilemma as many of these patients have comorbid conditions which are also associated with intestinal perforation. The authors present the case of a 47-year-old obese black female found to have massive pneumatosis intestinalis of the tranverse colon with a small amount of free intraperitoneal air. This case highlights the importance of recognizing pneumatosis intestinalis as a possible mimic of free intraabdominal air as well as a possible cause of benign pneumoperitoneum.

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.

PAI-1 gene expression is growth state-regulated in cultured human epidermal keratinocytes during progression to confluence and postwounding.

Growth of human keratinocytes (NHKs) in submerged cultures approximates a "wound" response generally considered equivalent to regenerative maturation. Within this context, PAI-1 expression in cultured NHKs appears to be growth state-regulated and is associated with specific NHK subpopulations undergoing migration and proliferation in response to wounding; NHKs transit through specific phases during growth to confluence. Basal layer keratinocytes comprise several classes of nucleated epidermal cells (designated "A," "B," and "C") which are distinguishable on the basis of RNA content, population generation time, and expression of basal cell marker proteins. "A" substrate cells initially give rise to expanding proliferating keratinocyte colonies in vitro, but are rapidly replaced (at the stage of 50-75% culture confluence) by transient amplifying "B" cells and, eventually, the larger "C" subpopulation which subsequently differentiates into suprabasal spinous cells during the postconfluent growth period. Expression of plasminogen activator inhibitor type-1 (PAI-1), a serine protease inhibitor and member of the serpin gene family which is synthesized by "activated" or migrating keratinocytes in vivo, was restricted to the preconfluent stages of cell growth in vitro, a condition equivalent to wound regeneration in situ. PAI-1 mRNA and protein expression was maximal in 50-75% confluent cultures correlating, thereby, with the emergence of the transient amplifying "B" cell population. Flow cytometric analysis revealed that PAI-1 is detected early in expanding NHK colonies, during the initial recruitment of basal cells from the "A" state into the "B" compartment in the absence of significant proliferation, suggesting that PAI-1 may be active in regulating early NHK migratory events, independent of cell proliferation. Thereafter, these PAI-1-expressing "A" cells are recruited into the "B" compartment, where they continue to migrate, proliferate, and enlarge, eventually giving rise to PAI-1-expressing "C" cells. By the time NHK cultures reach exponential growth, virtually no small "A" cells contain immunoreactive PAI-1. PAI-1 expression peaks during preconfluent growth and remains confined to larger basal cell phenotypes. Cellular accumulation of both PAI-1 mRNA and protein appeared to be cell cycle phase-specific and characteristic of progression through an activated G1 growth phase. Induced expression, moreover, was restricted to a "window" in G1 with PAI-1 mRNA evident within 2 h after serum addition to growth-arrested cells and attaining maximal levels (50-fold) at 10 h poststimulation. Induced PAI-1 expression, thus, appears to be a general characteristic of the activated epidermal phenotype in vitro as well as in vivo.

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.