Shear-Thinning Nanocomposite Hydrogels for the Treatment of Hemorrhage

Internal hemorrhaging is a leading cause of death after traumatic injury on the battlefield. Although several surgical approaches such as the use of fibrin glue and tissue adhesive have been commercialized to achieve hemostasis, these approaches are difficult to employ on the battlefield and cannot be used for incompressible wounds. Here, we present shear-thinning nanocomposite hydrogels composed of synthetic silicate nanoplatelets and gelatin as injectable hemostatic agents. These materials are demonstrated to decrease in vitro blood clotting times by 77%, and to form stable clot-gel systems. In vivo tests indicated that the nanocomposites are biocompatible and capable of promoting hemostasis in an otherwise lethal liver laceration. The combination of injectability, rapid mechanical recovery, physiological stability, and the ability to promote coagulation result in a hemostat for treating incompressible wounds in out-of-hospital, emergency conditions.United States. Army Research Office (Contract W911NF-13-D-0001)National Institutes of Health (U.S.) (Interdepartmental Biotechnology Training Program NIH/NIGMS 5T32GM008334

Production and Life History of Paragnetina Media (Walker) (Insecta: Plecoptera) in a Central Wisconsin Stream

The life history and production of the stonefly Paragnetina media (Walker) were studied in the lower Tomorrow River, a central Wisconsin stream, from June 1983 to August 1984. Adults exhibited a prolonged synchronous emergence beginning in early June. Individuals emerging early in the emergence period were on average statistically larger (p < 0.05) than those emerging later. Females deposited a mean of 4 egg masses in the laboratory, and mean fecundity was 1473 eggs. Eggs were kept at 5 constant temperatures (range 5-30 degrees C) in the laboratory. The percentage of eggs that hatched generally increased with increasing water temperature. Hatching time (days after oviposition at which 10%, 50%, and 90% of the eggs hatched) decreased with increasing water temperature, and the relationships between the two variables were well described by a hyperbola over the temperature range 15-25 degrees C; therefore, the time taken for development was expressed in units of degree-days (DD) above a threshold temperature. Hatching time for fertilized eggs was shorter than for unfertilized eggs. Larvae exhibited a complex semivoltine life cycle, with either a 2, 3, or mixed (2 and 3), year period of development. Length frequency analysis indicated variability in the life cycle duration depending on the time of egg hatch. Larvae that hatched in late summer following emergence required 3 years for development; whereas, larvae that hatched the following spring required about 2 years. The size-frequency distributions and the Janetschek method indicated ca. 26 instars for males and 30 instars for females. In later instars, female larvae were distinctly larger than males. Annual production, calculated from the sum of male and female production estimates using the size frequency method with a CPI of 940 d, was 7.13 g wet weight/m2 riffle, with P/B ratios of 5.04 (cohort) and 1.96 (annual). Production by females from 76% of total production.University of Wisconsin Stevens Point, and the Worth Compan

C-type natriuretic peptide inhibits leukocyte recruitment and platelet-leukocyte interactions via suppression of P-selectin expression

The multifaceted process of immune cell recruitment to sites of tissue injury is key to the development of an inflammatory response and involved in the pathogenesis of numerous cardiovascular disorders. We recently identified C-type natriuretic peptide (CNP) as an important endothelium-derived mediator that regulates vascular tone and protects against myocardial ischemia/reperfusion injury. Herein, we investigated whether CNP inhibits leukocyte recruitment and platelet aggregation and thereby exerts a potential antiinflammatory influence on the blood vessel wall. We assessed the effects of CNP on leukocyte-endothelial cell interactions in mouse mesenteric postcapillary venules in vivo in animals with high basal leukocyte activation (endothelial nitric oxide synthase knockout mice, eNOS(-/-)) or under acute inflammatory conditions (induced by interleukin-1β or histamine). CNP suppressed basal leukocyte rolling in eNOS(-/-) mice in a rapid, reversible, and concentration-dependent manner. These effects of CNP were mimicked by the selective natriuretic peptide receptor-C agonist cANF(4-23). CNP also suppressed leukocyte rolling induced by IL-1β or histamine, inhibited platelet-leukocyte interactions, and prevented thrombin-induced platelet aggregation of human blood. Furthermore, analysis of human umbilical vein endothelial cells, leukocytes, and platelets revealed that CNP selectively attenuates expression of P-selectin. Thus, CNP is a modulator of acute inflammation in the blood vessel wall characterized by leukocyte and platelet activation. These antiinflammatory effects appear to be mediated, at least in part, via suppression of P-selectin expression. These observations suggest that endothelial CNP might maintain an anti-atherogenic influence on the blood vessel wall and represent a target for therapeutic intervention in inflammatory cardiovascular disorders

Identification, regulation and role of Tissue Inhibitor of Metelloproteinases-4 (TIMP-4) in human platelets

1. Matrix metalloproteinase-2 (MMP-2) released during activation of human platelets by aggregating agents and cancer cells is known to stimulate platelet aggregation. 2. The expression, activity and role of tissue inhibitors of metalloproteinases (TIMPs), natural inhibitors of MMPs, in isolated human platelets were investigated. 3. Western blot, reverse zymography, immunogold electron microscopy, aggregometry (collagen-, thrombin and HT-1080 human fibrosarcoma cells-induced aggregation), flow cytometry and the release of (14)C-serotonin from labelled platelets recruited to the aggregate were used to characterize the presence and function of platelet TIMPs. 4. TIMP-4 (23 kDa) has been identified as the major MMP inhibitor (12–16 ng per 10(8) platelets) in human platelets. Platelets expressed lower (<1 ng per 10(8) platelets) amounts of TIMP-1. No other TIMPs were detected using Western blot analysis. 5. TIMP-4 co-localized with MMP-2 in resting platelets and was released upon platelet aggregation induced by collagen and thrombin. 6. Collagen resulted also in the release of higher molecular weight (60 kDa) complexes of TIMP-4. 7. The release of TIMP-4 was reduced by prostacyclin and S-nitroso-glutathione (GSNO), an NO donor. 8. Human recombinant TIMP-4 (rTIMP-4), but not human rTIMP-1, inhibited partially both platelet aggregation and recruitment. 9. The recombinant TIMP-4 potentiated the recruitment inhibitor effects of GSNO. 10. TIMP-4 was not released during platelet aggregation induced by HT-1080 cells. 11. Human rTIMP-4 exerted a biphasic effect on HT-1080 cells-induced aggregation. 12. Thus, TIMP-4 is the major intraplatelet MMP inhibitor and it is involved in regulation of platelet aggregation and recruitment