ABSTRACT
The triangularis sterni (TS) is an expiratory muscle that is passively stretched during inspiration. The magnitude of passive stretch depends upon the location of individual fibers within the TS muscle, with fibers located more caudally being stretched â¼ 5% to 10% more than fibers in the cephalad region. In the mdx mouse model for muscular dystrophy, the TS exhibits severe pathological alterations that are ameliorated by treatment with inhibitors of the NF-κB pathway. The purpose of this study was to assess the influence of passive stretch in vivo on fiber morphology in nondystrophic and mdx TS muscles, and the morphological benefits of treating mdx mice with two distinct NF-κB inhibitors, pyrrolidine dithiocarbamate (PDTC), and ursodeoxycholic acid (UDCA). Transmission electron microscopy revealed Z-line streaming, hypercontraction, and disassociation of the plasma membrane from the basal lamina in mdx fibers. In both nondystrophic and mdx TS muscles, fiber density was larger in more caudal regions. In comparison with nondystrophic TS, fibers in the mdx TS exhibited substantial reductions in diameter throughout all regions. In vivo treatment with either PDTC or UDCA tended to increase fiber diameter in the middle and decrease fiber diameter in the caudal TS, while reducing centronucleation in the middle region. These results suggest that passive stretch induces hypercontraction and plasma membrane abnormalities in dystrophic muscle, and that differences in the magnitude of passive stretch may influence fiber morphology and the actions of NF-κB inhibitors on dystrophic morphology.
Subject(s)
Muscle Fibers, Skeletal/metabolism , Muscle Fibers, Skeletal/pathology , Muscle Stretching Exercises , Muscular Dystrophies/metabolism , Muscular Dystrophies/pathology , NF-kappa B/antagonists & inhibitors , Animals , Cell Membrane/drug effects , Cell Membrane/metabolism , Cell Membrane/pathology , Mice , Mice, Inbred C57BL , Mice, Inbred mdx , Muscle Fibers, Skeletal/drug effects , Muscle Stretching Exercises/adverse effects , Muscular Dystrophies/drug therapy , NF-kappa B/physiology , Proline/analogs & derivatives , Proline/pharmacology , Proline/therapeutic use , Thiocarbamates/pharmacology , Thiocarbamates/therapeutic use , Ursodeoxycholic Acid/pharmacology , Ursodeoxycholic Acid/therapeutic useABSTRACT
Fallopian tube interruption is a common form of contraception in the United States. A significant portion of women who undergo these procedures are in their twenties and thirties. For a variety of reasons (eg, change in marital status, wish for additional children, death of children, religious concerns, psychological factors), many of these women later seek restoration of fertility through tubal anastomosis procedures. Using microsurgical techniques with minilaparotomy or laparoscopy procedures, surgeons are able to restore fallopian tube patency in many women. Positive surgical outcomes depend on the method of fallopian tube interruption, the type of tubal anastomosis performed, and the length of the fallopian tube segments being anastomosed.