Thermal and hydrolytic degradation of electrospun fish gelatin membranes

The thermal and hydrolytic degradation of electrospun gelatin membranes cross-linked with glutaraldehyde in vapor phase has been studied. In vitro degradation of gelatin membranes was evaluated in phosphate buffer saline solution at 37 °C. After 15 days under these conditions, a weight loss of 68% was observed, attributed to solvation and depolymerization of the main polymeric chains. Thermal degradation kinetics of the gelatin raw material and as-spun electrospun membranes showed that the electrospinning processing conditions do not influence polymer degradation. However, for cross-linked samples a decrease in the activation energy was observed, associated with the effect of glutaraldehyde cross-linking reaction in the inter- and intra-molecular hydrogen bonds of the protein. It is also shown that the electrospinning process does not affect the formation of the helical structure of gelatin chainsThis work was supported by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2011 and by projects project references NANO/NMed-SD/0156/2007 and PTDC/CTM-NAN/112574/2009. The authors also thank support from the COST Action MP1003, 2010 'European Scientific Network for Artificial Muscles'. DMC, JP and VS would like to acknowledge the FCT for the SFRH/BD/82411/2011, SFRH/BD/64901/2009 and SFRH/BPD/64958/2009 grants respectively

Development of gelatin-alginate hydrogels for burn wound treatment

Hydrogels are interesting as wound dressing for burn wounds to maintain a moist environment. Especially gelatin and alginate based wound dressings show strong potential. Both polymers are modified by introducing photocrosslinkable functionalities and combined to hydrogel films (gel-MA/alg-MA). In one protocol gel-MA films are incubated in alg-MA solutions and crosslinked afterward into double networks. Another protocol involves blending both and subsequent photocrosslinking. The introduction of alginate into the gelatin matrix results in phase separation with polysaccharide microdomains in a protein matrix. Addition of alg(-MA) to gel-MA leads to an increased swelling compared to 100% gelatin and similar to the commercial Aquacel Ag dressing. In vitro tests show better cell adhesion for films which have a lower alginate content and also have superior mechanical properties. The hydrogel dressings exhibit good biocompatibility with adaptable cell attachment properties. An adequate gelatin-alginate ratio should allow application of the materials as wound dressings for several days without tissue ingrowth

War-related psychological sequelae among emergency department patients in the former Republic of Yugoslavia

Background Residents of the Republic of Serbia faced civil war and a NATO-led bombing campaign in 1999. We sought to assess the burden of metal health dysfunction among emergency department (ED) patients presenting for care three years post-war in Serbia. Methods This study was conducted during July and August 2002 at two sites: a university hospital ED in Belgrade, Serbia and an ED in a remote district hospital serving a Serbian enclave in Laplje Selo, Kosovo. Investigators collected data on a systematic sample of non-acute patients presenting to the ED. All respondents completed a structured questionnaire assessing demographics and symptoms of post-traumatic stress disorder (PTSD) (using the Harvard Trauma Questionnaire), and major depression (using the Center for Epidemiologic Studies Depression Scale). Results A total of 562 respondents participated (310 in Belgrade, 252 in Laplje Selo); the response rate was 83.8%, 43% were female, and mean age was 37.6 years (SD = 13.4). Overall, 73 (13.0%) participants had symptoms consistent with PTSD, and 272 (49.2%) had symptoms consistent with depression. Sixty-six respondents had both disorders (11.9%). In separate multivariable logistic regression models, predictors of PTSD were refugee status and residence in Laplje Selo, and predictors of depression were older age, current unemployment, and lower social support. Conclusions Three years post-war, symptoms of PTSD and major depression in Serbia remained a significant public health concern, particularly among refugees, those suffering subsequent economic instability, and persons living in rural, remote areas

A review on mechanical considerations for chronically-implanted neural probes

International audienceThis review intends to present a comprehensive analysis of the mechanical considerations for chronically-implanted neural probes. Failure of neural electrical recordings or stimulation over time has shown to arise from foreign body reaction and device material stability. It seems that devices that match most closely with the mechanical properties of the brain would be more likely to reduce the mechanical stress at the probe/tissue interface, thus improving body acceptance. The use of low Young's modulus polymers instead of hard substrates is one way to enhance this mechanical mimetism, though compliance can be achieved through a variety of means. The reduction of probe width and thickness in comparison to a designated length, the use of soft hydrogel coatings and the release in device tethering to the skull, can also improve device compliance. Paradoxically, the more compliant the device, the more likely it will fail during the insertion process in the brain. Strategies have multiplied this past decade to offer partial or temporary stiffness to the device to overcome this buckling effect. A detailed description of the probe insertion mechanisms is provided to analyze potential sources of implantation failure and the need for a mechanically-enhancing structure. This leads us to present an overview of the strategies that have been put in place over the last ten years to overcome buckling issues. Particularly, great emphasis is put on bioresorbable polymers and their assessment for neural applications. Finally, a discussion is provided on some of the key features for the design of mechanically-reliable, polymer-based next generation of chronic neuroprosthetic devices