Structural remodeling of rat uterine veins in pregnancy.

OBJECTIVE: This study characterized the cellular remodeling that contributes to uterine venous growth during gestation and evaluated the effect of pregnancy on the mechanical properties of the uterine vein. STUDY DESIGN: Diameter and distensibility were calculated in pressurized uterine veins from virgin and pregnant (19-20 days of gestation) rats; the rates of cellular division (endothelial, vascular smooth muscle) were quantified with an intraperitoneal bromodeoxyuridine injection and immunohistochemistry. Elastin content, adrenergic nerve density, and wall thickness were determined in fixed uterine veins and quantified with an imaging program. RESULTS: There was a statistically significant increase in the diameter and mitotic indices (endothelial, vascular smooth muscle) in uterine veins from late pregnant versus nonpregnant animals. Adrenergic nerve density was diminished significantly during gestation. Venous distensibility increased during pregnancy, with an associated reduction in elastin content. CONCLUSION: Pregnancy results in coordinated and multifaceted structural remodeling of uterine veins with subsequent changes in caliber, mechanical properties, rates of cellular division, adrenergic innervation, and matrix composition.

Sequence polymorphism of dotA and mip alleles mediating invasion and intracellular replication of Legionella pneumophila.

Legionella pneumophila inhabit a variety of natural and man-made aquatic environments, where they live primarily as intracellular parasites of protozoans. Given the proper exposure, however, they can cause opportunistic pneumonic infections in humans. The products of two L. pneumophila genes, dotA and mip, are part of the mechanism mediating the initial invasion of eukaryotic cells, and subsequent intracellular survival and multiplication. In this study, DNA polymorphism of the dotA and mip genes was assessed for 17 clinical and environmental isolates by nucleotide sequencing to determine the level of sequence variation, rates of molecular evolution, and history of gene divergence. The mip gene is highly conserved, whereas dotA is extremely variable, with an average level of nucleotide diversity four times greater than that of mip. Gene trees for each locus support a division of the L. pneumophila isolates into two clonal lineages. There are several disagreements between the gene trees suggesting that although L. pneumophila has a clonal population structure, genetic exchange has contributed to genotypic variation among strains in nature.