Leukocyte- and Platelet-Rich Fibrin (L-PRF) Obtained from Smokers and Nonsmokers Shows a Similar Uniaxial Tensile Response In Vitro

We evaluated and compared the biomechanical properties of Leukocyte-and Platelet Rich Fibrin L-PRF clots and membranes derived from smoker and nonsmoker donors. Twenty venous-blood donors (aged 18 to 50 years) were included after signing informed consent forms. L-PRF clots were analyzed and then compressed to obtain L-PRF membranes. L-PRF clot and membrane samples were tested in quasi-static uniaxial tension and the stress-stretch response was registered and characterized. Furthermore, scanning electron microscope representative images were taken to see the fibrin structure from both groups. The analysis of stress-stretch curves allowed us to evaluate the statistical significance in differences between smoker and nonsmoker groups. L-PRF membranes showed a stiffer response and higher tensile strength when compared to L-PRF clots. However, no statistically significant differences were found between samples from smokers and nonsmokers. With the limitations of our in vitro study, we can suggest that the tensile properties of L-PRF clots and membranes from the blood of smokers and nonsmokers are similar. More studies are necessary to fully characterize the effect of smoking on the biomechanical behavior of this platelet concentrate, to further encourage its use as an alternative to promote wound healing in smokers.

The role of military forces in emergency management (civil-military interaction)

Those involved in emergency response and recovery, including the military, require an acute level of awareness of livelihoods that rely on livestock and their associated implications for human security. Emergencies cause injury and death and devastate livestock-based livelihoods, a key characteristic of the lives of many of the world's rural poor. The role for military forces in emergency management is expanding, and this can cause friction during an emergency due to competing agendas and objectives. Opportunities exist to make greater use of the military, such as providing support to livestock-based livelihoods, but there are challenges and barriers that must be overcome. A common framework for civil-military interaction may help to coordinate response efforts and enhance local and international responses to emergencies. The Livestock Emergency Guidelines and Standards and the proposed livelihood security model are constructs that can help to develop a shared understanding of the security environment during a livestock emergency response. Examples from the Philippines' response to Typhoons Sarika and Haima and Sri Lankan military agricultural engagements provide context for a proposed common operational framework.

Rapid fabrication of reinforced and cell-laden vascular grafts structurally inspired by human coronary arteries

Design strategies for small diameter vascular grafts are converging toward native-inspired tissue engineered grafts. A new automated technology is presented that combines a dip-spinning methodology for depositioning concentric cell-laden hydrogel layers, with an adapted solution blow spinning (SBS) device for intercalated placement of aligned reinforcement nanofibres. This additive manufacture approach allows the assembly of bio-inspired structural configurations of concentric cell patterns with fibres at specific angles and wavy arrangements. The middle and outer layers were tuned to structurally mimic the media and adventitia layers of native arteries, enabling the fabrication of small bore grafts that exhibit the J-shape mechanical response and compliance of human coronary arteries. This scalable automated system can fabricate cellularized multilayer grafts within 30 min. Grafts were evaluated by hemocompatibility studies and a preliminary in vivo carotid rabbit model. The dip-spinning-SBS technology generates constructs with native mechanical properties and cell-derived biological activities, critical for clinical bypass applications.

Impact of the Hydration States of Polymers on Their Hemocompatibility for Medical Applications: A Review

Water has a key role in the functioning of all biological systems, it mediates many biochemical reactions, as well as other biological activities such as material biocompatibility. Water is often considered as an inert solvent, however at the molecular level, it shows different behavior when sorbed onto surfaces like polymeric implants. Three states of water have been recognized: non-freezable water, which does not freeze even at -100 °C; intermediate water, which freezes below 0 °C; and, free water, which freezes at 0 °C like bulk water. This review describes the different states of water and the techniques for their identification and quantification, and analyzes their relationship with hemocompatibility in polymer surfaces. Intermediate water content higher than 3 wt % is related to better hemocompatibility for poly(ethylene glycol), poly(meth)acrylates, aliphatic carbonyls, and poly(lactic-co-glycolic acid) surfaces. Therefore, characterizing water states in addition to water content is key for polymer selection and material design for medical applications.

Salmonella Typhi shdA: pseudogene or allelic variant?

ShdA from Salmonella Typhimurium (ShdASTm) is a large outer membrane protein that specifically recognizes and binds to fibronectin. ShdASTm is involved in the colonization of the cecum and the Peyer's patches of terminal ileum in mice. On the other hand, shdA gene from Salmonella Typhi (shdASTy) has been considered a pseudogene (i.e. a nonfunctional sequence of genomic DNA) due to the presence of deletions and mutations that gave rise to premature stop codons. In this work we show that, despite the deletions and mutations, shdASTy is fully functional. S. Typhi ΔshdA mutants presented an impaired adherence and invasion of HEp-2 pre-treated with TGF-β1, an inducer of fibronectin production. Moreover, shdA from S. Typhi and S. Typhimurium seem to be equivalent since shdASTm restored the adherence and invasion of S. Typhi ΔshdA mutant to wild type levels. In addition, anti-FLAG mAbs interfered with the adherence and invasion of the S. Typhi shdA-3xFLAG strain. Finally, shdASTy encodes a detectable protein when heterologously expressed in Escherichia coli DH5α. The data presented here show that shdASTy is not a pseudogene, but a different functional allele compared with shdASTm.

Investigating the Release of a Hydrophobic Peptide from Matrices of Biodegradable Polymers: An Integrated Method Approach

The objectives of this work were: (1) to select suitable compositions of tyrosine-derived polycarbonates for controlled delivery of voclosporin, a potent drug candidate to treat ocular diseases, (2) to establish a structure-function relationship between key molecular characteristics of biodegradable polymer matrices and drug release kinetics, and (3) to identify factors contributing in the rate of drug release. For the first time, the experimental study of polymeric drug release was accompanied by a hierarchical sequence of three computational methods. First, suitable polymer compositions used in subsequent neural network modeling were determined by means of response surface methodology (RSM). Second, accurate artificial neural network (ANN) models were built to predict drug release profiles for fifteen polymers located outside the initial design space. Finally, thermodynamic properties and hydrogen-bonding patterns of model drug-polymer complexes were studied using molecular dynamics (MD) technique to elucidate a role of specific interactions in drug release mechanism. This research presents further development of methodological approaches to meet challenges in the design of polymeric drug delivery systems.

Multiscale analysis of water uptake and erosion in biodegradable polyarylates

The role of hydration in degradation and erosion of materials, especially biomaterials used in scaffolds and implants, was investigated by studying the distribution of water at length scales from 0.1 nm to 0.1 mm using Raman spectroscopy, small-angle neutron scattering (SANS), Raman confocal imaging, and scanning electron microscopy (SEM). The measurements were demonstrated using L-tyrosine derived polyarylates. Bound- and free- water were characterized using their respective signatures in the Raman spectra. In the presence of deuterium oxide (D(2)O), H-D exchange occurred at the amide carbonyl but was not detected at the ester carbonyl. Water appeared to be present in the polymer even in regions where there was little evidence for N-H to N-D exchange. SANS showed that water is not uniformly dispersed in the polymer matrix. The distribution of water can be described as mass fractals in polymers with low water content (~5 wt%), and surface fractals in polymers with larger water content (15 to 60 wt%). These fluctuations in the density of water distribution are presumed to be the precursors of the ~ 20 μm water pockets seen by Raman confocal imaging, and also give rise to 10-50 μm porous network seen in SEM. The surfaces of these polymers appeared to resist erosion while the core of the films continued to erode to form a porous structure. This could be due to differences in either the density of the polymer or the solvent environment in the bulk vs. the surface, or a combination of these two factors. There was no correlation between the rate of degradation and the amount of water uptake in these polymers, and this suggests that it is the bound-water and not the total amount of water that contributes to hydrolytic degradation.