Perioperative Results and Risk Factors for In-Hospital Mortality In Patients With Stanford Type A Aortic Dissection Undergoing Sun's Procedure - A Single Center Study.

BACKGROUND: The study was to analyze the therapeutic effect and risk factors of in-hospital mortality in patients with acute Stanford type A aortic dissection operated by Sun's procedure. METHODS: From Jan. 2010 to March 2016, 72 patients whose data was fully accessible underwent Sun's procedure in our hospital due to acute Stanford type A aortic dissection. Patients were divided into the survival group and the death group, and the risk factors for in-hospital mortality were collected and analyzed. RESULTS: All 72 patients were diagnosed as acute Stanford type A aortic dissection by CT angiography in which the ascending aorta, aortic arch and descending aorta were involved; these patients were operated by Sun's procedure. The operation of proximal aorta included 39 Bentall procedure, one David surgery, and 32 ascending aorta replacement. The in-hospital mortality rate was 19.4% (14 patients). Studies showed the risk factors for the in-hospital mortality included the body mass index, cardiopulmonary bypass time, operation time, intraoperative transfusion of red blood cells and plasma volume, and the total perioperative transfusion of red blood cells, plasma and cryoprecipitate volume. Independent risk factors included the body mass index and cardiopulmonary bypass time. CONCLUSION: Acute Stanford type A aortic dissection is a severe, complex disease with high in-hospital mortality, though the Sun's procedure is an effective surgical approach in treating this kind of disease in some center. Body mass index and cardiopulmonary bypass time are independent risk factors for in-hospital mortality.

Electrically conductive graphene/polyacrylamide hydrogels produced by mild chemical reduction for enhanced myoblast growth and differentiation.

Graphene and graphene derivatives, such as graphene oxide (GO) and reduced GO (rGO), have been extensively employed as novel components of biomaterials because of their unique electrical and mechanical properties. These materials have also been used to fabricate electrically conductive biomaterials that can effectively deliver electrical signals to biological systems. Recently, increasing attention has been paid to electrically conductive hydrogels that have both electrical activity and a tissue-like softness. In this study, we synthesized conductive graphene hydrogels by mild chemical reduction of graphene oxide/polyacrylamide (GO/PAAm) composite hydrogels to obtain conductive hydrogels. The reduced hydrogel, r(GO/PAAm), exhibited muscle tissue-like stiffness with a Young's modulus of approximately 50kPa. The electrochemical impedance of r(GO/PAAm) could be decreased by more than ten times compared to that of PAAm and unreduced GO/PAAm. In vitro studies with C2C12 myoblasts revealed that r(GO/PAAm) significantly enhanced proliferation and myogenic differentiation compared with unreduced GO/PAAm and PAAm. Moreover, electrical stimulation of myoblasts growing on r(GO/PAAm) graphene hydrogels for 7days significantly enhanced the myogenic gene expression compared to unstimulated controls. As results, our graphene-based conductive and soft hydrogels will be useful as skeletal muscle tissue scaffolds and can serve as a multifunctional platform that can simultaneously deliver electrical and mechanical cues to biological systems. STATEMENT OF SIGNIFICANCE: Graphene-based conductive hydrogels presenting electrical conductance and a soft tissue-like modulus were successfully fabricated via mild reduction of graphene oxide/polyacrylamide composite hydrogels to study their potential to skeletal tissue scaffold applications. Significantly promoted myoblast proliferation and differentiation were obtained on our hydrogels. Additionally, electrical stimulation of myoblasts via the graphene hydrogels could further upregulate myogenic gene expressions. Our graphene-incorporated conductive hydrogels will impact on the development of new materials for skeletal muscle tissue engineering scaffolds and bioelectronics devices, and also serve as novel platforms to study cellular interactions with electrical and mechanical signals.

Polypyrrole-incorporated conductive hyaluronic acid hydrogels.

BACKGROUND: Hydrogels that possess hydrophilic and soft characteristics have been widely used in various biomedical applications, such as tissue engineering scaffolds and drug delivery. Conventional hydrogels are not electrically conductive and thus their electrical communication with biological systems is limited. METHOD: To create electrically conductive hydrogels, we fabricated composite hydrogels of hyaluronic acid and polypyrrole. In particular, we synthesized and used pyrrole-hyaluronic acid-conjugates and further chemically polymerized polypyrrole with the conjugates for the production of conductive hydrogels that can display suitable mechanical and structural properties. RESULTS: Various characterization methods, using a rheometer, a scanning electron microscope, and an electrochemical analyzer, revealed that the PPy/HA hydrogels were soft and conductive with ~ 3 kPa Young's modulus and ~ 7.3 mS/cm conductivity. Our preliminary in vitro culture studies showed that fibroblasts were well attached and grew on the conductive hydrogels. CONCLUSION: These new conductive hydrogels will be greatly beneficial in fields of biomaterials in which electrical properties are important such as tissue engineering scaffolds and prosthetic devices.

Polypyrrole/Alginate Hybrid Hydrogels: Electrically Conductive and Soft Biomaterials for Human Mesenchymal Stem Cell Culture and Potential Neural Tissue Engineering Applications.

Electrically conductive biomaterials that can efficiently deliver electrical signals to cells or improve electrical communication among cells have received considerable attention for potential tissue engineering applications. Conductive hydrogels are desirable particularly for neural applications, as they can provide electrical signals and soft microenvironments that can mimic native nerve tissues. In this study, conductive and soft polypyrrole/alginate (PPy/Alg) hydrogels are developed by chemically polymerizing PPy within ionically cross-linked alginate hydrogel networks. The synthesized hydrogels exhibit a Young's modulus of 20-200 kPa. Electrical conductance of the PPy/Alg hydrogels could be enhanced by more than one order of magnitude compared to that of pristine alginate hydrogels. In vitro studies with human bone marrow-derived mesenchymal stem cells (hMSCs) reveal that cell adhesion and growth are promoted on the PPy/Alg hydrogels. Additionally, the PPy/Alg hydrogels support and greatly enhance the expression of neural differentiation markers (i.e., Tuj1 and MAP2) of hMSCs compared to tissue culture plate controls. Subcutaneous implantation of the hydrogels for eight weeks induces mild inflammatory reactions. These soft and conductive hydrogels will serve as a useful platform to study the effects of electrical and mechanical signals on stem cells and/or neural cells and to develop multifunctional neural tissue engineering scaffolds.