Physiologic compliance in engineered small-diameter arterial constructs based on an elastomeric substrate.

Compliance mismatch is a significant challenge to long-term patency in small-diameter bypass grafts because it causes intimal hyperplasia and ultimately graft occlusion. Current engineered grafts are typically stiff with high burst pressure but low compliance and low elastin expression. We postulated that engineering small arteries on elastomeric scaffolds under dynamic mechanical stimulation would result in strong and compliant arterial constructs. This study compares properties of engineered arterial constructs based on biodegradable polyester scaffolds composed of either rigid poly(lactide-co-glycolide) (PLGA) or elastomeric poly(glycerol sebacate) (PGS). Adult baboon arterial smooth muscle cells (SMCs) were cultured in vitro for 10 days in tubular, porous scaffolds. Scaffolds were significantly stronger after culture regardless of material, but the elastic modulus of PLGA constructs was an order of magnitude greater than that of porcine carotid arteries and PGS constructs. Deformation was elastic in PGS constructs and carotid arteries but plastic in PLGA constructs. Compliance of arteries and PGS constructs were equivalent at pressures tested. Altering scaffold material from PLGA to PGS significantly decreased collagen content and significantly increased insoluble elastin content in constructs without affecting soluble elastin concentration in the culture medium. PLGA constructs contained no appreciable insoluble elastin. This research demonstrates that: (1) substrate stiffness directly affects in vitro tissue development and mechanical properties; (2) rigid materials likely inhibit elastin incorporation into the extracellular matrix of engineered arterial tissues; and (3) grafts with physiologic compliance and significant elastin content can be engineered in vitro after only days of cell culture

Abdominal aortic aneurysm repair with the Zenith stent graft: Short to midterm results

AbstractPurpose: The purpose of this study was to assess the short-term and mid-term results of endovascular aneurysm repair with the Zenith stent graft in a single-center prospective study. Method: Between October 1998 and July 2001, we used the Zenith stent graft for elective endovascular aneurysm repair in 116 patients, six of whom were women. The mean age was 75 years, and the mean aneurysm diameter was 60.3 ± 8.8 mm. Stent grafts were oversized 10% to 20% relative to computed tomographic (CT) scan-based diameter measurements. All repairs were performed in the operating room through surgically exposed femoral arteries. The results were assessed before discharge with three-phase, contrast-enhanced CT scan and plain abdominal radiograph. These studies were repeated at 1, 6, 12, and 24 months after operation. Follow-up periods ranged from 1 to 34 months. Results: No failed insertions and no conversions to open surgery occurred. The diameter of the main body of the stent graft was 28 mm or more in 73 patients (63%). Additional stents were inserted during surgery to treat kinking in eight patients (6.9%) and renal artery encroachment in two patients (1.7%). Mean fluoroscopy time was 35.1 ± 18.3 minutes, contrast load was 146 ± 53 mL (350 mg/mL), and estimated blood loss was 249 ± 407 mL. The major complication rate was 9.5%, and the minor complication rate was 10.3%. The perioperative complications were myocardial infarction in four patients, arrythmia in four patients, and pulmonary embolism, renal failure, stroke, small bowel obstruction, femoral stenosis, digital embolism, and graft limb thrombosis in one patient each. All 116 patients went home from the hospital, but one patient died 2 weeks later of a combination of pulmonary embolism and myocardial infarction. Endoleak was seen on the first CT scan in 16 patients (15%); 15 were type II, and one was type III. No endoleaks of type I or IV were seen. Additional interventions were performed for each of the following conditions: type II endoleak (n = 4), type III endoleak (n = 1), femoral clamp injury (n = 1), renal artery stenosis (n = 1), and graft limb occlusion (n = 1). One patient had acute aneurysm dilatation and rupture caused by a type II endoleak through the inferior mesenteric artery 6 months after stent graft implantation. No cases were seen of late graft occlusion, stent graft migration, stent fracture, barb fracture, or secondary endoleak. Conclusion: The Zenith device is safe, versatile, and effective in the short to medium term. Most patients need wide stent grafts (≥28 mm proximally and ≥16 mm distally) to achieve 10% to 20% oversizing to prevent type I endoleak. (J Vasc Surg 2002;36:217-25.

Citation++: Data citation, provenance, and documentationNew draft item

<p>The dawning of the digital research age –</p> <p>computational science, computational social</p> <p>science, and the digital humanities – brings</p> <p>with it both enormous potential and challenges.</p> <p>Visions of interactive publication,</p> <p>open data, reproducible results, and massive</p> <p>digital collections are exciting, opening</p> <p>up new research frontiers and the promise</p> <p>of more rapid dissemination of and building</p> <p>upon research ouput. However, to date,</p> <p>little of this vision has been realized. It remains</p> <p>challenging to reuse digital artifacts,</p> <p>precisely identify data used in a publication,</p> <p>and reproduce the results of published</p> <p>work. We leverage research in data citation</p> <p>and provenance collection and maintenance</p> <p>to prototype and evaluate a provenanceenabled</p> <p>citation service to facilitate better</p> <p>access to data sets and reproducibility of research</p> <p>results.</p