Differences in the Movement Skills and Physical Qualities of Elite Senior & Academy Rugby League Players.

The aim of the present study was to investigate (a) the differences in the movement skills and physical qualities between academy and senior rugby league players, and (b) the relationships between movement skills and physical qualities. Fifty-five male rugby league players (Senior, n=18; Under 19 n=23; Under 16, n=14) undertook a physical testing battery including anthropometric (stature & body mass), strength (isometric mid-thigh pull; IMTP) and power (countermovement jump; CMJ) qualities, alongside the athletic ability assessment (AAA; comprised of overhead squat, double lunge, single-leg Romanian deadlift, press-up and pull-up exercises). Univariate analysis of variance demonstrated significant (p<0.001) differences in body mass, IMTP peak force, CMJ mean power, and AAA movement skills between groups. The greatest observed differences for total movement skills, peak force and mean power were identified between Under 16 and 19 academy age groups. Spearman's rank correlation coefficients demonstrated a significant moderate (r=0.31) relationship between peak force and total movement skill. Furthermore, trivial (r=0.01) and small (r=0.13; r=0.22) relationships were observed between power qualities and total movement skill. These findings highlight that both movement skills and physical qualities differentiate between academy age groups, and provides comparative data for English senior and academy rugby league players

Overcoming the problem of multicollinearity in sports performance data: A novel application of partial least squares correlation analysis

Objectives Professional sporting organisations invest considerable resources collecting and analysing data in order to better understand the factors that influence performance. Recent advances in non-invasive technologies, such as global positioning systems (GPS), mean that large volumes of data are now readily available to coaches and sport scientists. However analysing such data can be challenging, particularly when sample sizes are small and data sets contain multiple highly correlated variables, as is often the case in a sporting context

Current dietetic practices of obesity management in Saudi Arabia and comparison with Australian practices and best practice criteria

Objective: To describe the dietetic practices of the treatment of obesity in Saudi Arabia and compare this with best practice criteria and the practice in Australia. Methods: Anonymous questionnaires were completed by dietitians in Saudi Arabia. The topics included barriers to obesity management, demand and level of service and strategies and approaches used for weight management. Best practice scores were based on those used to assess Australian dietitians. Results: 253 dietitians participated in the survey. Of these, 175 (69 %) were involved in the management of obesity. The best practice score for Australian dietitians was slightly but significantly greater than the scores of Saudi dietitians (mean 41.6 vs 38.8; p \u3c0.001), (median 43 vs 39). There was also a significant correlation between the best practice score and years of experience (r = 0.26, p \u3c0.001). The most common assessment approaches were assessment of BMI (87%) and exercise habits (81%) while the most common strategies for obesity management were; dietary total fat reduction (92%) and increase incidental daily activity (92%). The major barrier for establishment of a weight management clinic reported by 49% of participants was inadequate resources. Conclusion: Saudi Arabian dietetic practice for the management of obesity does incorporate most best practice recommendations, but some specific elements are rarely used

Three Regions within Acta Promote Arp2/3 Complex-Mediated Actin Nucleation and Listeria monocytogenes Motility

The Listeria monocytogenes ActA protein induces actin-based motility by enhancing the actin nucleating activity of the host Arp2/3 complex. Using systematic truncation analysis, we identified a 136-residue NH2-terminal fragment that was fully active in stimulating nucleation in vitro. Further deletion analysis demonstrated that this fragment contains three regions, which are important for nucleation and share functional and/or limited sequence similarity with host WASP family proteins: an acidic stretch, an actin monomer–binding region, and a cofilin homology sequence. To determine the contribution of each region to actin-based motility, we compared the biochemical activities of ActA derivatives with the phenotypes of corresponding mutant bacteria in cells. The acidic stretch functions to increase the efficiency of actin nucleation, the rate and frequency of motility, and the effectiveness of cell–cell spread. The monomer-binding region is required for actin nucleation in vitro, but not for actin polymerization or motility in infected cells, suggesting that redundant mechanisms may exist to recruit monomer in host cytosol. The cofilin homology sequence is critical for stimulating actin nucleation with the Arp2/3 complex in vitro, and is essential for actin polymerization and motility in cells. These data demonstrate that each region contributes to actin-based motility, and that the cofilin homology sequence plays a principal role in activation of the Arp2/3 complex, and is an essential determinant of L. monocytogenes pathogenesis

The Pore-Forming Toxin Listeriolysin O Mediates a Novel Entry Pathway of L. monocytogenes into Human Hepatocytes

Intracellular pathogens have evolved diverse strategies to invade and survive within host cells. Among the most studied facultative intracellular pathogens, Listeria monocytogenes is known to express two invasins-InlA and InlB-that induce bacterial internalization into nonphagocytic cells. The pore-forming toxin listeriolysin O (LLO) facilitates bacterial escape from the internalization vesicle into the cytoplasm, where bacteria divide and undergo cell-to-cell spreading via actin-based motility. In the present study we demonstrate that in addition to InlA and InlB, LLO is required for efficient internalization of L. monocytogenes into human hepatocytes (HepG2). Surprisingly, LLO is an invasion factor sufficient to induce the internalization of noninvasive Listeria innocua or polystyrene beads into host cells in a dose-dependent fashion and at the concentrations produced by L. monocytogenes. To elucidate the mechanisms underlying LLO-induced bacterial entry, we constructed novel LLO derivatives locked at different stages of the toxin assembly on host membranes. We found that LLO-induced bacterial or bead entry only occurs upon LLO pore formation. Scanning electron and fluorescence microscopy studies show that LLO-coated beads stimulate the formation of membrane extensions that ingest the beads into an early endosomal compartment. This LLO-induced internalization pathway is dynamin-and F-actin-dependent, and clathrin-independent. Interestingly, further linking pore formation to bacteria/bead uptake, LLO induces F-actin polymerization in a tyrosine kinase-and pore-dependent fashion. In conclusion, we demonstrate for the first time that a bacterial pathogen perforates the host cell plasma membrane as a strategy to activate the endocytic machinery and gain entry into the host cell