Effectiveness and safety of manual hemostasis facilitated by the SyvekPatch with one hour of bedrest after coronary angiography using six-French catheters

pGlcNAc Nanofiber Treatment of Cutaneous Wounds Stimulate Increased Tensile Strength and Reduced Scarring via Activation of Akt1

Treatment of cutaneous wounds with poly-N-acetyl-glucosamine containing nanofibers (pGlcNAc), a novel polysaccharide material derived from a marine diatom, results in increased wound closure, antibacterial activities and innate immune responses. We have shown that Akt1 plays a central role in the regulation of these activities. Here, we show that pGlcNAc treatment of cutaneous wounds results in a smaller scar that has increased tensile strength and elasticity. pGlcNAc treated wounds exhibit decreased collagen content, increased collagen organization and decreased myofibroblast content. A fibrin gel assay was used to assess the regulation of fibroblast alignment in vitro. In this assay, fibrin lattice is formed with two pins that provide focal points upon which the gel can exert force as the cells align from pole to pole. pGlcNAc stimulation of embedded fibroblasts results in cellular alignment as compared to untreated controls, by a process that is Akt1 dependent. We show that Akt1 is required in vivo for the pGlcNAc-induced increased tensile strength and elasticity. Taken together, our findings suggest that pGlcNAc nanofibers stimulate an Akt1 dependent pathway that results in the proper alignment of fibroblasts, decreased scarring, and increased tensile strength during cutaneous wound healing.

A review of current methods for assessing hemostasis in vivo and introduction to a potential alternative approach

A validated method for assessing hemostasis in vivo is critical for testing the hemostatic efficacy of therapeutic agents in preclinical animal models and in patients with inherited bleeding disorders, such as von Willebrand disease (VWD) and hemophilia A, or with acquired bleeding disorders such as those resulting from medications or disease processes. In this review, we discuss current methods for assessing hemostasis in vivo and the associated challenges. We also present ARFI-Monitored Hemostatic Challenge; a new, potentially alternate method for in vivo hemostasis monitoring that is in development by our group.

Integrin-dependent Akt1 activation regulates PGC-1 expression and fatty acid oxidation

BACKGROUND

Poly-N-acetyl glucosamine nanofibers derived from a marine diatom have been used to increase cutaneous wound healing. These nanofibers exert their activity by specifically activating integrins, which makes them a useful tool for dissecting integrin-mediated pathways. We have shown that short-fiber poly-N-acetyl glucosamine nanofiber (sNAG) treatment of endothelial cells results in increased cell motility and metabolic rate in the absence of increased cell proliferation.

RESULTS

Using a Seahorse Bioanalyzer to measure oxygen consumption in real time, we show that sNAG treatment increases oxygen consumption rates, correlated with an integrin-dependent activation of Akt1. Akt1 activation leads to an increase in the expression of the transcriptional coactivator, peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α). This is not due to increased mitochondrial biogenesis, but is associated with an increase in the expression of pyruvate dehydrogenase kinase 4 (PDK4), suggesting regulation of fatty acid oxidation. Blockade of fatty acid oxidation with etomoxir, an O-carnitine palmitoyltransferase-1 inhibitor, blocks the sNAG-dependent increased oxygen consumption. (3)H-palmitate uptake experiments indicate a PDK4-dependent increase in fatty acid oxidation, which is required for nanofiber-induced cell motility.

CONCLUSIONS

Our findings imply a linear pathway whereby an integrin-dependent activation of Akt1 leads to increased PGC-1α and PDK4 expression resulting in increased energy production by fatty acid oxidation.

Anti-bacterial effects of poly-N-acetyl-glucosamine nanofibers in cutaneous wound healing: requirement for Akt1

Background

Treatment of cutaneous wounds with poly-N-acetyl-glucosamine nanofibers (sNAG) results in increased kinetics of wound closure in diabetic animal models, which is due in part to increased expression of several cytokines, growth factors, and innate immune activation. Defensins are also important for wound healing and anti-microbial activities. Therefore, we tested whether sNAG nanofibers induce defensin expression resulting in bacterial clearance.

Methodology

The role of sNAG in defensin expression was examined using immunofluoresence microscopy, pharmacological inhibition, and shRNA knockdown in vitro. The ability of sNAG treatment to induce defensin expression and bacterial clearance in WT and AKT1−/− mice was carried out using immunofluoresent microscopy and tissue gram staining. Neutralization, using an antibody directed against β-defensin 3, was utilized to determine if the antimicrobial properties of sNAG are dependent on the induction of defensin expression.

Conclusions/Findings

sNAG treatment causes increased expression of both α- and β-type defensins in endothelial cells and β-type defensins in keratinocytes. Pharmacological inhibition and shRNA knockdown implicates Akt1 in sNAG-dependent defensin expression in vitro, an activity also shown in an in vivo wound healing model. Importantly, sNAG treatment results in increased kinetics of wound closure in wild type animals. sNAG treatment decreases bacterial infection of cutaneous wounds infected with Staphylococcus aureus in wild type control animals but not in similarly treated Akt1 null animals. Furthermore, sNAG treatment of S. aureus infected wounds show an increased expression of β-defensin 3 which is required for sNAG-dependent bacterial clearance. Our findings suggest that Akt1 is involved in the regulation of defensin expression and the innate immune response important for bacterial clearance. Moreover, these findings support the use of sNAG nanofibers as a novel method for enhancing wound closure while simultaneously decreasing wound infection.

ARFI ultrasound for in vivo hemostasis assessment postcardiac catheterization, part II: pilot clinical results

In this second of a two part series, we present pilot clinical data demonstrating Acoustic Radiation Force Impulse (ARFI) ultrasound for monitoring the onset of subcutaneous hemostasis at femoral artery puncture sites (arteriotomies), in vivo. We conducted a randomized, reader-blinded investigation of 20 patient volunteers who underwent diagnostic percutaneous coronary catheterization. After sheath removal (6 French), patients were randomized to treatment with either standard of care manual compression alone or, to expedite hemostasis, manual compression augmented with a p-GlcNAc fiber-based hemostatic dressing (Marine Polymer Technologies, Danvers MA). Concurrent with manual compression, serial ARFI imaging began at the time of sheath removal and continued every minute for 15 min. Serial data sets were processed with custom software to (1) estimate the time of hemostasis onset, and (2) render hybrid ARFI/B-Mode images to highlight displacements considered to correspond to extravasted blood. Images were read by an observer blinded to the treatment groups. Average estimated times to hemostasis in patient volunteers treated with manual compression alone (n = 10) and manual compression augmented by hemostatic dressing (n = 9) were, respectively, 13.00 +/- 1.56 and 9.44 +/- 3.09 min, which are statistically significantly different (p = 0.0065, Wilcoxon two-sample test). Example images are shown for three selected patient volunteers. These pilot data suggest that ARFI ultrasound is relevant to monitoring subcutaneous bleeding from femoral arteriotomies clinically and that time to hemostasis was significantly reduced by use of the hemostatic dressing.

Poly-N-acetyl glucosamine nanofibers regulate endothelial cell movement and angiogenesis: dependency on integrin activation of Ets1

Poly-N-acetyl glucosamine (pGlcNAc) nanofiber-derived materials effectively achieve hemostasis during surgical procedures. Treatment of cutaneous wounds with pGlcNAc in a diabetic mouse animal model causes marked increases in cell proliferation and angiogenesis. We sought to understand the effect of the pGlcNAc fibers on primary endothelial cells (EC) in culture and found that pGlcNAc induces EC motility. Cell motility induced by pGlcNAc fibers is blocked by antibodies directed against alphaVbeta3 and alpha5beta1 integrins, both known to play important roles in the regulation of EC motility, in vitroand in vivo. pGlcNAc treatment activates mitogen-activated protein kinase and increases Ets1, vascular endothelial growth factor (VEGF) and interleukin 1 (IL-1) expression. pGlcNAc activity is not secondary to its induction of VEGF; inhibition of the VEGF receptor does not inhibit the pGlcNAc-induced expression of Ets1 nor does pGlcNAc cause the activation of VEGF receptor. Both dominant negative and RNA interference inhibition of Ets1 blocks pGlcNAc-induced EC motility. Antibody blockade of integrin results in the inhibition of pGlcNAc-induced Ets1 expression. These findings support the hypothesis that pGlcNAc fibers induce integrin activation which results in the regulation of EC motility and thus in angiogenesis via a pathway dependent on the Ets1 transcription factor and demonstrate that Ets1 is a downstream mediator of integrin activation.

Determining best practice: Comparison of three methods of femoral sheath removal after cardiac interventional procedures

OBJECTIVE

To test the null hypothesis that there is no significant difference between 3 methods of sheath removal: manual compression, mechanical compression with the Compressar, and mechanical compression with the Femostop.

METHODS

The research design was experimental. Ninety patients were randomly assigned using a random-numbers table to undergo one of 3 methods of sheath removal. The principal investigator (L.M.B.) requested the patients' consent to undergo randomization of the sheath removal. Post procedure, each patient was told which method of sheath removal he or she would undergo based on results of the random-numbers table assignment.

RESULTS

There were no significant differences between the groups with regard to age, body mass index, sheath size, heparin utilization, antiplatelet agents, or use of IIb-IIIa inhibitors. The complications between the methodologies for sheath removal were statistically significant. Patients who underwent manual sheath removal had fewer complications compared with those who underwent sheath removal using the Compressar or Femostop (chi2 P = .04). When complications were compared with the other parameters, only the presence of postprocedure heparin infusion (chi2 P = .014) and ACT values (Student t test P = .044) proved to be statistically significant.

CONCLUSIONS

Based on the results of this study, staff in the study setting are currently exploring manual sheath removal as the preferred practice. Randomized controlled studies with larger sample populations at multicenter research sites are needed to ensure generalizability of results to larger populations. When using manual pressure application in conjunction with closure pad devices, hold times can be decreased, thus resulting in cost savings through decreased equipment use, earlier discharge times, and improved bed utilization.