Rationale: Mutations in GJC2 and GJA1, encoding connexins (Cxs) 47 and 43 respectively, are linked to lymphedema, but the underlying mechanisms are unknown. Because efficient lymph transport relies on the coordinated contractions of lymphatic muscle cells (LMCs) and the electrical coupling of those through Cxs, Cx-related lymphedema is proposed to result from dyssynchronous contractions of lymphatic vessels. Objective: Determine which Cx isoforms in LMCs and/or lymphatic endothelial cells (LECs) are required for the entrainment of lymphatic contraction waves and efficient lymph transport. Methods and Results: We developed novel methods to quantify the spatiotemporal entrainment of lymphatic contraction waves and used optogenetic techniques to analyze calcium signaling within and between the LMC and LEC layers. Genetic deletion of the major LEC Cxs (Cx43, Cx47, or Cx37) revealed that none were necessary for the synchronization of the global calcium events that triggered propagating contraction waves. We identified Cx45 in human and mouse LMCs as the critical Cx mediating the conduction of pacemaking signals and entrained contractions. Smooth muscle-specific Cx45 deficiency resulted in 10–18-fold reduction in conduction speed, partial-to-severe loss of contractile coordination, and impaired lymph pump function ex vivo and in vivo. Cx45-deficiency resulted in profound inhibition of lymph transport in vivo, but only under an imposed gravitational load. Conclusions: Our results: 1) identify Cx45 as the Cx isoform mediating the entrainment of the contraction waves in LMCs; 2) show that major endothelial Cxs are dispensable for the entrainment of contractions; 3) reveal a lack of coupling between LECs and LMCs, in contrast to arterioles; 4) point to lymphatic valve defects, rather than contraction dyssynchrony, as the mechanism underlying GJC2- or GJA1-related lymphedema; and 5) show that a gravitational load exacerbates lymphatic contractile defects in the intact mouse hindlimb, which is likely critical for the development of lymphedema in the adult mouse.

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Although bariatric surgery effectively reduces the mortality risk from obesity-related comorbidities [1,2], it is associated with a 1-5% risk of anastomotic complications. Anastomotic leaks have traditionally been treated with a combination of drainage with long-term parenteral nutrition or postanastomotic enteral nutrition, allowing the leak to heal. Strictures at the gastrojejunostomy are initially treated with repeated endoscopic dilation, but revisional bariatric surgery is needed for refractory strictures with its associated high complication rate. Chronic fistulas are initially treated conservatively but often need high-risk revisional surgery. Recently, endoscopic covered stents have been used successfully for treatment of anastomotic complications after esophageal resection [3][4][5]. Case series evaluating stents to treat anastomotic leaks after Roux-en-Y gastric bypass have shown success [6][7][8][9]. However, the numbers of patients enrolled in these studies are small, and only short-term outcomes are reported.The primary aim of this study is to present long-term healing rates after endoscopically placed covered stents in the treatment of various anastomotic complications after bariatric surgery. The secondary aim is to analyze symptom improvement scores, complications, and factors affecting stent migration. Materials and methodsWe performed a retrospective analysis of all patients treated with endoscopic stents for staple-line complications after bariatric surgery from The study was approved by the University of Missouri Institutional Review Board.Inclusion criteria were patients who underwent either Roux-en-Y gastric bypass or sleeve gastrectomy with subsequent anastomotic complications defined as acute staple-line leaks, chronic anastomotic fistulas or refractory anastomotic strictures. Acute leaks were defined as those occurring within 1 month postoperatively. Refractory anastomotic strictures were defined as persistent clinically significant strictures that were endoscopically dilated more than twice without resolution. Chronic fistulas were defined as enterocutaneous or gastrogastric fistulas for longer than 1 month.The stents were placed using both endoscopic and fluoroscopic guidance with endoscopy being used to delineate the area of leak, stricture or fistula. This pathology was then marked with either a radiopaque marker on the skin surface or by injecting water-soluble contrast in the mucosa adjacent to the pathology to use as an internal marker. Strictures were identified and dilated for at least

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Laser energy at a wavelength of 480 nm was applied in 1-microseconds pulses of 3 to 10 mJ to two models of vasospasm. Rabbit common carotid arteries (CCA's) were constricted chronically by the application of human blood within a silicone sheath. Peak vasospasm developed 24 to 48 hours later, and persisted for up to 6 days. Endovascular laser treatment was delivered to 40 CCA's via a 200-microns diameter silica quartz fiber introduced through the femoral artery. The CCA caliber increased from 60% of the pre-vasospasm control diameter to a minimum post-laser diameter of 83% of control. No instances of laser-induced perforation or of arterial thrombosis were observed for up to 60 days after treatment. Prophylactic laser application to nine normal vessels was able to attenuate the development of vasospasm if blood was applied immediately thereafter (88% vs. 59% of control diameter, p less than 0.02), but not if blood was applied 7 days later. Studies in 16 normal CCA's established that there was a considerable margin between the laser energy required to induce dilatation and that which caused perforation, providing that the fiber remained relatively central within the artery. Morphological examination demonstrated focal loss of endothelial cells immediately after laser application, followed approximately 7 days later by the development of areas of intimal hyperplasia. Only minimal changes were observed in the medial or adventitial layers. In a second study, the basilar artery of seven dogs was constricted chronically by two intracisternal injections of autologous blood 3 days apart. Five dogs received endovascular laser treatment 7 or 10 days after the first injection, when basilar artery diameter was reduced to a mean of 61% and 77% of control, respectively. Immediately following treatment, basilar artery diameter increased to 104% and 102% of resting diameter, respectively. Both untreated and laser-treated arteries were smaller than the control diameter at 30 days (80% and 82%, respectively), but in each group the vasodilatory response to hypercapnia was preserved. These findings indicate that 1-microsecond laser pulses are well tolerated by systemic and cerebral arteries in two different animal models, and suggest that the 480-nm pulsed-dye laser may have an application for the treatment or prophylaxis of cerebral vasospasm.