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OBJECTIVE: This study reports the technical aspects and 30-day outcomes of the prospective, multicenter early feasibility study designed to evaluate the GORE EXCLUDER Thoracoabdominal Branch Endoprosthesis (TAMBE; W. L. Gore & Associates, Flagstaff, Ariz). METHODS: Thirteen patients with pararenal or extent IV thoracoabdominal aortic aneurysms were prospectively enrolled at five U.S sites and one non-U.S. site from 2014 to 2016. The TAMBE included four portals with either retrograde or antegrade renal portal configuration and used GORE VIABAHN Balloon-Expandable Endoprosthesis (W. L. Gore & Associates) for stenting of the renal and mesenteric arteries. The primary end point was procedural safety at 30 days, defined by absence of major adverse events, including any-cause mortality, myocardial infarction, stroke, paraplegia, bowel ischemia, respiratory failure, severe acute kidney injury (>50% decline in estimated glomerular filtration rate), dialysis, and procedural blood loss >1000 mL. RESULTS: There were 11 male and two female patients with a mean age of 69 ± 8 years. Mean aneurysm diameter was 61 ± 13 mm. A total of 52 renal and mesenteric arteries were incorporated (4 vessels/patient). Technical success was achieved in 12 patients (92%). One patient had inadvertent occlusion of a right renal artery due to dissection. There was no mortality, aneurysm rupture, conversion to open repair, dialysis, or spinal cord injury. Mean length of hospital stay was 5 ± 3 days. At 30 days, four patients (31%) had major adverse events, all due to procedural blood loss >1000 mL. One patient had a type I endoleak at the distal renal branch, which was successfully treated by placement of an additional renal stent before dismissal. Computed tomography angiography at 30 days showed patent target vessels and no type I or type III endoleak. CONCLUSIONS: This study confirms the early feasibility of the TAMBE for treatment of pararenal and extent IV thoracoabdominal aortic aneurysms. The high technical success, no mortality, and low morbidity rate support continuation of clinical investigation in a larger population of patients.

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With the advancement of the field of biotribology, considerable interest has arisen in the study of cell and tissue frictional properties. From the perspective of medical device development, the frictional properties between a rigid surface and underlying cells and tissues are of a particular clinical interest. As with many bearing surfaces, it is likely that contact asperities exist at the size scale of single cells and below. Thus, a technique to measure cellular frictional properties directly would be beneficial from both a clinical and a basic science perspective. In the current study, an atomic force microscope (AFM) with a 5 µm diameter borosilicate spherical probe simulating endovascular metallic stent asperities was used to characterize the surface frictional properties of vascular smooth muscle cells (VSMCs) in contact with a metallic endovascular stent. Various treatments were used to alter cell structure, in order to better understand the cellular components and mechanisms responsible for governing frictional properties. The frictional coefficient of the probe on VSMCs was found to be approximately 0.06. This frictional coefficient was significantly affected by cellular crosslinking and cytoskeletal depolymerization agents. These results demonstrate that AFM-based lateral force microscopy is a valuable technique to assess the friction properties of individual single cells on the micro-scale.

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A number of recent studies have demonstrated the effectiveness of atomic force microscopy (AFM) for characterization of cellular stress-relaxation behavior. However, this technique's recent development creates considerable need for exploration of appropriate mechanical models for analysis of the resultant data and of the roles of various cytoskeletal components responsible for governing stress-relaxation behavior. The viscoelastic properties of vascular smooth muscle cells (VSMCs) are of particular interest due to their role in the development of vascular diseases, including atherosclerosis and restenosis. Various cytoskeletal agents, including cytochalasin D, jasplakinolide, paclitaxel, and nocodazole, were used to alter the cytoskeletal architecture of the VSMCs. Stress-relaxation experiments were performed on the VSMCs using AFM. The quasilinear viscoelastic (QLV) reduced-relaxation function, as well as a simple power-law model, and the standard linear solid (SLS) model, were fitted to the resultant stress-relaxation data. Actin depolymerization via cytochalasin D resulted in significant increases in both rate of relaxation and percentage of relaxation; actin stabilization via jasplakinolide did not affect stress-relaxation behavior. Microtubule depolymerization via nocodazole resulted in nonsignificant increases in rate and percentage of relaxation, while microtubule stabilization via paclitaxel caused significant decreases in both rate and percentage of relaxation. Both the QLV reduced-relaxation function and the power-law model provided excellent fits to the data (R(2)=0.98), while the SLS model was less adequate (R(2)=0.91). Data from the current study indicate the important role of not only actin, but also microtubules, in governing VSMC viscoelastic behavior. Excellent fits to the data show potential for future use of both the QLV reduced-relaxation function and power-law models in conjunction with AFM stress-relaxation experiments.

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It was hypothesized that supercritical carbon dioxide (SC-CO(2)) treatment could serve as an alternative sterilization method at various temperatures (40-105 degrees C), CO(2) pressures (200-680 atm), and treatment times (25 min to 6 h), and with or without the use of a passive additive (distilled water, dH(2)O) or an active additive (hydrogen peroxide, H(2)O(2)). While previous researchers have shown that SC-CO(2) possesses antimicrobial properties, sterilization effectiveness has not been shown at sufficiently low treatment temperatures and cycle times, using resistant bacterial spores. Experiments were conducted using Geobacillus stearothermophilus and Bacillus atrophaeus spores. Spore strips were exposed to SC-CO(2) in commercially available supercritical fluid extraction and reaction systems, at varying temperatures, pressures, treatment times, and with or without the use of a passive additive, such as dH(2)O, or an active additive, such as H(2)O(2). Treatment parameters were varied from 40 to 105 degrees C, 200-680 atm, and from 25 min to 6 h. At 105 degrees C without H(2)O(2), both spore types were completely deactivated at 300 atm in 25 min, a shorter treatment cycle than is obtained with methods in use today. On the other hand, with added H(2)O(2) (<100 ppm), 6 log populations of both spore types were completely deactivated using SC-CO(2) in 1 h at 40 degrees C. It was concluded from the data that large populations of resistant bacterial spores can be deactivated with SC-CO(2) with added H(2)O(2)at lower temperatures and potentially shorter treatment cycles than in most sterilization methods in use today.

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