Anti-Bacterial Effects of Poly-N-Acetyl-Glucosamine Nanofibers in Cutaneous Wound Healing: Requirement for Akt1

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.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.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

Emotions and motivation in mathematics education: theoretical considerations and empirical contributions

Emotions and motivation are important prereq-uisites, mediators, and outcomes of learning and achieve-ment. In this article, we first review major theoretical approaches and empirical findings in research on students\u27 emotions and motivation in mathematics, including a dis-cussion of how classroom instruction can support emo-tions and motivation. Based on this review, we encourage researchers from mathematics education and other dis-ciplines of educational research to combine their efforts. Second, we provide an overview of the contributions in this special issue, most of which reflect such a combination of efforts by considering perspectives from both mathematics education and other fields of educational research. Finally, we consider the neglect of intervention studies and outline directions for future research. We identify intervention studies that target emotions and motivation as one promis-ing but so far underrepresented line of research in mathe-matics education and review results from existing interven-tion studies. For future research, we suggest that researchers should implement fine-grained concepts, assessment instru-ments, theoretical hypotheses, and methods of analysis tai-lored to the specific features of the mathematical domain to adequately investigate students\u27 emotions and motivation in this domain