Non-Overlapping Functions for Pyk2 and FAK in Osteoblasts during Fluid Shear Stress-Induced Mechanotransduction

Mechanotransduction, the process by which cells convert external mechanical stimuli such as fluid shear stress (FSS) into biochemical changes, plays a critical role in maintenance of the skeleton. We have proposed that mechanical stimulation by FSS across the surfaces of bone cells results in formation of unique signaling complexes called mechanosomes that are launched from sites of adhesion with the extracellular matrix and with other bone cells [1]. Deformation of adhesion complexes at the cell membrane ultimately results in alteration of target gene expression. Recently, we reported that focal adhesion kinase (FAK) functions as a part of a mechanosome complex that is required for FSS-induced mechanotransduction in bone cells. This study extends this work to examine the role of a second member of the FAK family of non-receptor protein tyrosine kinases, proline-rich tyrosine kinase 2 (Pyk2), and determine its role during osteoblast mechanotransduction. We use osteoblasts harvested from mice as our model system in this study and compared the contributions of Pyk2 and FAK during FSS induced mechanotransduction in osteoblasts. We exposed Pyk2+/+ and Pyk2−/− primary calvarial osteoblasts to short period of oscillatory fluid flow and analyzed downstream activation of ERK1/2, and expression of c-fos, cyclooxygenase-2 and osteopontin. Unlike FAK, Pyk2 was not required for fluid flow-induced mechanotransduction as there was no significant difference in the response of Pyk2+/+ and Pyk2−/− osteoblasts to short periods of fluid flow (FF). In contrast, and as predicted, FAK−/− osteoblasts were unable to respond to FF. These data indicate that FAK and Pyk2 have distinct, non-redundant functions in launching mechanical signals during osteoblast mechanotransduction. Additionally, we compared two methods of generating FF in both cell types, oscillatory pump method and another orbital platform method. We determined that both methods of generating FF induced similar responses in both primary calvarial osteoblasts and immortalized calvarial osteoblasts

Development of a biocompatible small-diameter vascular prothesis derived from small intestinal submucosa

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Demographics of Prehospital Helicopter EMS Responses in Rural Florida

AbstractIntroduction:Helicopter emergency medical service (HEMS) systems typically are described in terms of their role in the care and transport of trauma victims, while their function(s) in the care of patients with medical illness goes unrecognized.Methods:Review of 575 prehospital HEMS missions by a flight program located in rural, north-central Florida over a five-year period, was performed to define demographics regarding the nature of the call.Results:Scene responses for trauma victims comprised 63% of these missions, while patients with medical illnesses comprised 37%. The incidence of medical scene responses is significantly higher in this review than has been noted in previous reports.Conclusion:1) In rural settings, patients with medical illnesses comprise a major share of prehospital HEMS responses; 2) HEMS flight crews should be competent in treatment of prehospital medical patients, and their protocols reflect the needs of these patients; and 3) EMS providers must be aware of the role of HEMS in the transport of the medical patient.</jats:sec

Histological and adhesiogenic characterization of the Zenapro Hybrid Hernia Repair Device

AbstractBackgroundA major clinical problem relating to hernia repair is the formation of intra-abdominal, post-surgical adhesions when mesh products are used to reinforce the abdominal wall. To achieve better outcomes, more technologically-advanced products designed to achieve permanence of repair while eliminating serious complications such as adhesion formation are needed. This study was designed to assess the histological remodeling and adhesiogenic properties of the Zenapro™ Hybrid Hernia Repair Device as compared to uncoated and coated polypropylene.Materials and MethodsZenapro™, Prolene® and Ventralight® ST Mesh were implanted to repair full-thickness abdominal wall defects in rabbits and rats and were allowed to survive for various lengths of time. Animals were euthanized, the implants were identified, and the extent and tenacity of adhesions were evaluated. Tissue samples were collected and evaluated for inflammation, integration of the mesh with the abdominal wall, and collagen deposition.ResultsA significant difference was found in the extent of adhesions in the Prolene group as compared to the Zenapro group (p = 0.021) and the Ventralight ST group (p = 0.04) in the rat study. The tenacity of the adhesions in the Prolene mesh group trended higher than in the other groups but failed to reach statistical significance. Histological evaluation demonstrated that collagen accumulation was greatest for the Zenapro implants as compared to either the Ventralight ST or Prolene samples. At the conclusion of 6-months in the rabbit model, the Zenapro sites showed signs of a thicker repair composed of more organized mature collagen than was seen in the Ventralight ST samples. Neither device was found to elicit any sort of detrimental inflammatory tissue reaction.ConclusionA combination hernia device composed of a complete extracellular matrix with a synthetic mesh can result in enhanced tissue ingrowth and neovascularization while maintaining high tensile strength and mitigating adhesiogenic effects

A Positive Pressure Universal Gripper Based on the Jamming of Granular Material

Abstract—We describe a simple passive universal gripper, con-sisting of a mass of granular material encased in an elastic mem-brane. Using a combination of positive and negative pressure, the gripper can rapidly grip and release a wide range of objects that are typically challenging for universal grippers, such as flat ob-jects, soft objects, or objects with complex geometries. The gripper passively conforms to the shape of a target object, then vacuum-hardens to grip it rigidly, later utilizing positive pressure to reverse this transition—releasing the object and returning to a deformable state. We describe the mechanical design and implementation of this gripper and quantify its performance in real-world testing sit-uations. By using both positive and negative pressure, we demon-strate performance increases of up to 85 % in reliability, 25 % in error tolerance, and the added capability to shoot objects by fast ejection. In addition, multiple objects are gripped and placed at once while maintaining their relative distance and orientation. We conclude by comparing the performance of the proposed gripper with others in the field. Index Terms—End effectors, grain size, jamming, manipulators, pressure control. I