KTS is characterized by a clinical triad of extremity varicosities, cutaneous vascular malformations, and hypertrophy of soft tissues and long bones. The diagnosis is clinically supplemented with magnetic resonance imaging and computed tomography. Although this syndrome is associated with significant comorbidities, such as pain, edema, ulcerations, and pruritus, it is rarely the cause of death. The backbone of treatment is nonoperative in nature but should be supplemented with minimally invasive, endovascular, and rarely open surgical procedures for refractory cases.
This study examined Schwann cell behavior during paranodal demyelination induced by beta,beta'-iminodipropionitrile (IDPN). The stimuli for Schwann cell proliferation, extensively studied in vitro, are less well understood in vivo. Most in vivo systems previously used to examine Schwann cell proliferation in disease are dominated by loss of internodal myelin sheaths. As used in this study, IDPN administration produces neurofilamentous axonal swellings and paranodal demyelination, without segmental demyelination or fiber degeneration. We asked whether Schwann cells would proliferate following the restricted paranodal demyelination that accompanies the axonal swellings, and if so what the sources and distributions of new Schwann cells might be. IDPN was given as a single large dose (2 ml/kg) to 21-d-old rats. Neurofilamentous axonal swellings formed in the proximal regions of motor axons, reaching their greatest enlargement in the root exit zone 8 d after IDPN administration. These swellings subsequently migrated distally down the nerves at rates approaching 1 mm/d. The axonal enlargement was consistently associated with displacement of the myelin sheath attachment sites into internodal regions, and consequent paranodal demyelination. This stage was associated with perikaryal changes, including nucleolar enlargement, "girdling" of the perikaryon, and formation of attenuated stalks separating the perinuclear region from the external cytoplasmic collar. Schwann cells proliferated abundantly during this stage. Daughter Schwann cells migrated within the endoneurial space (outside the nerve fiber basal laminae) to overlie the demyelinated paranodes of swollen nerve fibers. In these regions, local proliferation of Schwann cells continued, resulting in large paranodal clusters of Schwann cells. As the axonal calibers subsequently returned to normal, the outermost myelin lamellae of the original internodes returned to their paranodal attachment sites and the supernumerary Schwann cells disappeared. Formation of short internodes, segmental demyelination, and nerve fiber loss were rare phenomena. These results indicate that paranodal demyelination is a sufficient stimulus to excite abundant Schwann cell proliferation; neither internodal demyelination nor myelin breakdown is a necessary stimulus for mitosis. The 3H-thymidine incorporation studies indicated that the sources of new Schwann cells included markedly increased division of the Schwann cells of unmyelinated fibers and, as they formed, supernumerary Schwann cells. In addition, there were rare examples of 3H-thymidine incorporation by Schwann cells associated with myelinated nerve fibers.(ABSTRACT TRUNCATED AT 400 WORDS)
Hydrogen sulfide (HS) is an endogenous gasotransmitter that has vasodilatory properties. It may be a novel therapy for intestinal ischemia-reperfusion (I/R) injury. We hypothesized that ) HS would improve postischemic survival, mesenteric perfusion, mucosal injury, and inflammation compared with vehicle and ) the benefits of HS would be mediated through endothelial nitric oxide. C57BL/6J wild-type and endothelial nitric oxide synthase knockout (eNOS KO) mice were anesthetized, and a midline laparotomy was performed. Intestines were eviscerated, the small bowel mesenteric root identified, and baseline intestinal perfusion was determined using laser Doppler. Intestinal ischemia was established by temporarily occluding the superior mesenteric artery. Following ischemia, the clamp was removed, and the intestines were allowed to recover. Either sodium hydrosulfide (2 nmol/kg or 2 µmol/kg NaHS) in PBS vehicle or vehicle only was injected into the peritoneum. Animals were allowed to recover and were assessed for mesenteric perfusion, mucosal injury, and intestinal cytokines. values< 0.05 were significant. HS improved mesenteric perfusion and mucosal injury scores following I/R injury. However, in the setting of eNOS ablation, there was no improvement in these parameters with HS therapy. Application of HS also resulted in lower levels of intestinal cytokine production following I/R. Intraperitoneal HS therapy can improve mesenteric perfusion, intestinal mucosal injury, and intestinal inflammation following I/R. The benefits of HS appear to be mediated through endothelial nitric oxide-dependent pathways. HS is a gaseous mediator that acts as an anti-inflammatory agent contributing to gastrointestinal mucosal defense. It promotes vascular dilation, mucosal repair, and resolution of inflammation following intestinal ischemia and may be exploited as a novel therapeutic agent. It is unclear whether HS works through nitric oxide-dependent pathways in the intestine. We appreciate that HS was able to improve postischemic recovery of mesenteric perfusion, mucosal integrity, and inflammation. The beneficial effects of HS appear to be mediated through endothelial nitric oxide-dependent pathways.
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