Different degradation rates of nanofiber vascular grafts in small and large animal models

Nanofiber vascular grafts have been shown to create neovessels made of autologous tissue, by in vivo scaffold biodegradation over time. However, many studies on graft materials and biodegradation have been conducted in vitro or in small animal models, instead of large animal models, which demonstrate different degradation profiles. In this study, we compared the degradation profiles of nanofiber vascular grafts in a rat model and a sheep model, while controlling for the type of graft material, the duration of implantation, fabrication method, type of circulation (arterial/venous), and type of surgery (interposition graft). We found that there was significantly less remaining scaffold (i.e., faster degradation) in nanofiber vascular grafts implanted in the sheep model compared with the rat model, in both the arterial and the venous circulations, at 6 months postimplantation. In addition, there was more extracellular matrix deposition, more elastin formation, more mature collagen, and no calcification in the sheep model compared with the rat model. In conclusion, studies comparing degradation of vascular grafts in large and small animal models remain limited. For clinical translation of nanofiber vascular grafts, it is important to understand these differences.     

Case report: Complete esophageal obliteration secondary to cytomegalovirus in AIDS patient

HIV‐related benign esophageal strictures have been reported secondary to idiopathic esophageal ulceration, cytomegalovirus (CMV) esophagitis, herpetic esophagitis, and increased sensitivity to radiation therapy. Despite extensive and deep nature of CMV ulceration, stricture formation is uncommon. There have been anecdotal reports of esophageal strictures secondary to CMV infection in HIV patients. Esophageal stricture has been reported during active CMV ulceration as well as subsequent to successful treatment. Esophageal strictures secondary to CMV have also been reported without prior ulceration. We report a patient with CMV esophagitis presenting with ulceration and stricture who developed total obliteration of esophageal lumen following treatment with gancyclovir.     

Flexor tendon repair using shape memory alloy suture: a biomechanical evaluation

The purpose of the current study was to test in vitro a new shape memory alloy suture for flexor tendon repair. Forty fresh-frozen human anatomic flexor superficialis and profundus tendons were divided and repaired via the cruciate four-strand technique using one of two suture materials (the shape memory alloy suture and the 4-0 Ethibond suture). The forces required to cause a 1, 2, and 3 mm gap, ultimate load to failure, and repair stiffness were compared. Twenty specimens of each suture material also were tensile tested for load to failure, tensile strength, and elongation at failure. The shape memory alloy suture had a significantly higher mean resistance force to 1, 2, and 3 mm gap formation than the 4-0 Ethibond suture (47 N versus 31 N, 51 N versus 36 N, and 57 N versus 41 N, respectively). The shape memory alloy suture repair was 40% stronger than the 4-0 Ethibond suture (61.9 +/- 8.8 N versus 44.3 +/- 10.6 N). Repair with the shape memory alloy suture was significantly stiffer than repair with the 4-0 Ethibond suture (8.1 +/- 1.0 N/mm versus 6.1 +/- 0.9 N/mm). The load to failure and tensile strength of the shape memory alloy suture were significantly higher than that of the 4-0 Ethibond suture. The values of elongation for the two materials were not significantly different. The results of the current study suggest that the shape memory alloy suture may be superior to the 4-0 Ethibond suture in resisting gap formation in the range of forces generated in the early rehabilitation protocol and may be the future material of choice for tendon repairs.     

Vascularized bone graft for scaphoid nonunion

The management of recalcitrant nonunion of the scaphoid can be frustrating. Recent understanding of the vascular anatomy of the distal radius has helped in the management of these problems. Vascularized bone grafting for scaphoid nonunion has improved the union rates. Consequently, familiarity with this procedure is an important tool for any surgeon who treats scaphoid nonunion. Although there are numerous publications discussing both the vascular anatomy of the distal radius and the scaphoid, little is written about the surgical technique. This study reviews the literature on scaphoid nonunion and outlines the authors' experience with this procedure.     

Cholestatic liver diseases: An era of emerging therapies

Recently the field of cholestasis has expanded enormously reflecting an improved understanding of the molecular mechanisms underlying bile secretion and its perturbation in chronic cholestatic disease. Novel anti-cholestatic therapeutic options have been developed for patients not favorably responding to ursodeoxycholic acid (UDCA), the current standard treatment for cholestatic liver disease. Important novel treatment targets now also include nuclear receptors involved in bile acid (BA) homoeostasis like farnesoid X receptor and G protein-coupled receptors e.g., the G-protein-coupled BA receptor “transmembrane G coupled receptor 5”. Fibroblast growth factor-19 and enterohepatic BA transporters also deserve attention as additional drug targets as does the potential treatment agent norUDCA. In this review, we discuss recent and future promising therapeutic agents and their potential molecular mechanisms in cholestatic liver disorders.     

The "hybrid flip-over" technique for anterior leaflet prolapse repair

Repair of the anterior mitral leaflet or bi-leaflet prolapse is technically more demanding than repair of the posterior mitral leaflet. Although several techniques have been proposed for the repair of anterior mitral leaflet prolapse during bi-leaflet repair, practical challenges remain, including the determination of the appropriate length for artificial chords. Herein we describe a novel and reproducible technique for bi-leaflet mitral valve repair, including those with extensive anterior mitral leaflet prolapse.