Vaginal Leiomyoma: Unusual Case Presentation.

Vaginal leiomyomas are rare to exist as a primary tumor of vagina. Approximately 300 cases have been reported in world literature. They usually arise from anterior vaginal wall and are firm to hard in consistency with varied clinical presentations. Here, we report a case of vaginal leiomyoma presenting as mass per vagina, diagnosed postoperatively with the help of histopathological and immunohistochemical studies.

Purification, physicochemical and regulatory properties of serine hydroxymethyltransferase from sheep liver.

Serine hydroxymethyltransferase (EC 2.1.2.1) was purified from the cytosolic fraction of sheep liver by ammonium sulphate fractionation, CM-Sephadex chromatography, gel filtration using Ultrogel ACA 34 and Blue Sepharose affinity chromatography. The homogeneity of the enzyme was rigorously established by Polyacrylamide gel and sodium dodecyl sulphate-polyacrylamide gel electrophoresis, isoelectrofocusing, ultracentrifugation, immunodiffusion and Immunoelectrophoresis. The enzyme was a homotetramer with a molecular weight of 210,000 ±5000. The enzyme showed homotropic cooperative interactions with tetrahydrofolate (nH =2.8) and a hyperbolic saturation pattern with L-serine. At the lowest concentration of tetrahydrofolate used (0.2 mM), only 5% of the added folate was oxidized during preincubation and assay. The nH value was independent of the time of preincubation. Preincubation of the enzyme with serine resulted in a partial loss of the cooperative interactions (nH =1.6) with tetrahydrofolate. The enzyme was regulated allosterically by interaction with nicotinamide nucleotides; NADH was a positive effector while NAD+ was a negative allosteric effector. The subunit interactions were retained even at the temperature optimum of 60°C unlike in the case of the monkey liver enzyme, where these interactions were absent at higher temperatures. D-Cycloserine, a structural analogue of serine caused a sigmoid pattern of inhibition, in contrast with the observations on the monkey liver enzyme. Cibacron blue F3GA completely inhibited the enzyme and this inhibition could be reversed by tetrahydrofolate. Unlike in the monkey liver enzyme, NAD+ and NADH gave considerable protection against this inhibition. The sheep liver enzyme differs significantly in its kinetic and regulatory properties from the serine hydroxymethyltransferases isolated from other sources.