Cationic Polysaccharides Bind to the Endothelial Cell Surface Extracellular Matrix Involving Heparan Sulfate.

Cationic polysaccharides have been extensively studied for drug delivery via the bloodstream, yet few have progressed to clinical use. Endothelial cells lining the blood vessel wall are coated in an anionic extracellular matrix called the glycocalyx. However, we do not fully comprehend the charged polysaccharide interactions with the glycocalyx. We reveal that the cationic polysaccharide poly(acetyl, arginyl) glucosamine (PAAG) exhibits the highest association with the endothelial glycocalyx, followed by dextran (neutral) and hyaluronan (anionic). Furthermore, we demonstrate that PAAG binds heparan sulfate (HS) within the glycocalyx, leading to intracellular accumulation. Using an in vitro glycocalyx model, we demonstrate a charge-based extent of association of polysaccharides with HS. Mechanistically, we observe that PAAG binding to HS occurs via a condensation reaction and functionally protects HS from degradation. Together, this study reveals the interplay between polysaccharide charge properties and interactions with the endothelial cell glycocalyx toward improved delivery system design and application.

Does Skill Performance Influence Young Children's Perceived Physical Competence?

Children's self-perceived competence is critical for their engagement in fundamental motor skills (FMS), although these perceptions are highly inaccurate until around age seven (grade 2). Moreover, FMS competence is highly correlated with physical activity engagement in childhood. In this study we examined: (a) if children's perceptions of their FMS competence differed after they were allowed to perform the skill or observe their performance, and (b) if the accuracy of children's perceived competence changed under those conditions. Child participants (N = 76; K-second grade) judged their own competence for three physical skills (running, skipping and dribble or hopping) on the Harter and Pike Pictorial Scale of Perceived Competence and Social Acceptance under three conditions: (a) a no-performance baseline, (b) after performing each skill, and (c) after observing themselves performing the skill. A repeated measures analysis of variance (ANOVA) indicated that their perceived competence differed across these conditions for running but not for skipping/hopping (p = .556) or for dribbling (p = .368). Spearman's rho correlations showed that their perceived running competence scores better predicted their actual competence after observing their performance (rs = .25, p = .029) than after other conditions. Both performing and observing their performance were associated with changes in perceptions of running competence. Future research should focus on how and when children's perceived competence is assessed and how perceptions relate to FMS and physical activity engagement.

The Role of Vascular Cells in Pancreatic Beta-Cell Function.

Insulin-producing ß-cells constitute the majority of the cells in the pancreatic islets. Dysfunction of these cells is a key factor in the loss of glucose regulation that characterizes type 2 diabetes. The regulation of many of the functions of ß-cells relies on their close interaction with the intra-islet microvasculature, comprised of endothelial cells and pericytes. In addition to providing islet blood supply, cells of the islet vasculature directly regulate ß-cell activity through the secretion of growth factors and other molecules. These factors come from capillary mural pericytes and endothelial cells, and have been shown to promote insulin gene expression, insulin secretion, and ß-cell proliferation. This review focuses on the intimate crosstalk of the vascular cells and ß-cells and its role in glucose homeostasis and diabetes.