In view of an appreciable increase in resistance of Staphylococcus aureus to the conventional antibiotics, it is desired to develop new effective drugs. Antimicrobial peptides (AMPs) seem to be attractive candidates. In general, AMPs samples used for in vitro studies consist of a peptide, counter-ion, and water. The presence of the counter-ion could be significant as it affects peptide secondary structure and biological activity. The purpose of this study was to estimate the impact of counter-ion on antistaphylococcal activity of selected AMPs (CAMEL, citropin 1.1, LL-37, pexiganan, temporin A). To do this, three kinds of salts were prepared, namely, acetates, hydrochlorides, and trifluoroacetates. In addition, the hemolytic activity against human red blood cells (hRBCs) and cytotoxicity (HaCaT) were determined. The results indicate that there is a substantial difference between different salts, but the pattern is not consistent for the peptides. In general, the antistaphylococcal activity decreased in the order: CAMEL > temporin A > pexiganan > citropin 1.1 ≫ LL-37. The highest selectivity indexes were determined for CAMEL hydrochloride, pexiganan acetate, and temporin A trifluoroacetate. This study shows how important is to take into account the kind of counter-ions when designing novel peptide-based antimicrobials.

The purpose of this long-term retrospective analysis was to determine whether anthropometric and physical performance data could predict success in elite youth Scottish soccer players. Stature, body mass, sprint, jump and aerobic performance were collected from 512 players (U10 to U17) across a 10-year period. Players participated in an average of four profiling sessions (range: 1-14) and up to a maximum of three per year (August, December, and May) with standardisation applied to the surface, test order, time, and protocols. One hundred players were awarded professional contracts. Associations between variables were quantified with mixed-effects linear models. Prediction was assessed with least absolute shrinkage and selection operator (LASSO) regression developed on a training set (2/3 data) and tested with proportion of error on a leave-out (1/3 data) test set. Confidence intervals were obtained through bootstrap LASSO samples. A strong relative age bias was identified with 50% of successful players born in the first quarter of the year. Successful players were on average taller and performed better in sprint and jump tests (p<0.05). However, effects were small and even when variables were combined, proportion of errors identified were similar to random guessing (0.45[95%CI:0.41 -0.49]). The results indicate that whilst successful players as youths demonstrate on average distinct anthropometric and physical profiles, these differences are unlikely to provide a reliable source to predict success within an already talented group. Practitioners should use data collected to guide exercise prescription but be aware of its substantive limitations in predicting success in isolation.

This study quantified and compared the weekly locomotor activity and subjective load between elite and development loan youth soccer players registered to a primary club. Development loan players were loaned to a lower-league club and trained part-time with their loan club whilst being available for development fixtures and training with the primary club. Data were collected in 16 squad players and 4 development loan players at loan clubs across a 41 week competitive phase of the 2018/2019 season. Analysis was completed on total distance (m), PlayerLoadTM (au), low intensity running (<14.4 km·h−1, m), running (19.8–24.98 km·h−1, m), sprinting (>24.98 km·h−1, m), accelerations (>2 m·s−2 count) and decelerations (<−2 m·s−2, count). Point estimates for the development loan players consistently showed lower weekly values than squad players for all variables ranging from 5.2% (weekly sRPE) to 16.8% (weekly sprint distance covered). Differences, however, were not found to be statistically significant ( p ≥ 0.07). Variance ranged from 23.6% (weekly distance) to 37.7% (weekly high-intensity accelerations). Although the goals of a development loan are likely to be multifactorial, this is the first study to quantify and compare locomotor activities and subjective loading of players within the development loan environment.

Background: Sprint interval training (SIT) performed on a cycle ergometer is a common mode of training and has become increasingly studied as an exercise intervention to improve a range of physical performance outcomes.Objectives: The primary objective was to synthesise findings from published research and through meta-analysis quantify the effect of SIT and potential moderators on physical performance outcomes with healthy adults. The secondary objective was to assess the methodological quality of included studies and the existence of small study effects. Methods:The review included studies from 2000 to 2020 based on the following criteria: 1) healthy participants 18 to 45 years; 2) minimum 2-week SIT intervention comprising "all out" sprints up to a maximum of 30 seconds on a cycle ergometer; 3) cohort or control group design; 4) pre-post intervention outcomes that could be categorised as aerobic (e.g. VO2max, incremental time); anaerobic (e.g. peak power, fatigue index); mixed aerobic/anaerobic (e.g. critical power test, peak power across repeated tests); or muscular force (e.g. maximal voluntary contraction, peak force). Methodological quality was assessed using a modified Downs and Black Checklist and a strategy based on the recommendations of the Grading of Recommendations Assessment Development and Evaluation working group. All metaanalyses were conducted within a Bayesian framework to facilitate probabilistic interpretations of mean standardised effect sizes obtained from both non-controlled and non-exercisecontrolled data.Results: Fifty-five studies met the inclusion criteria, with 50% graded as moderate methodological quality and 42% graded as low methodological quality. Most studies (58%) comprised an intervention of 4 weeks or less, with the collective research featuring a wide range of training protocols. The primary meta-analysis was conducted on non-controlled effect sizes from 403 outcomes. The analysis identified a small to medium effect of improved physical performance with SIT (ES0.5 = 0.43 [95%CrI: 0.35 to 0.52]). Moderator analyses identified large differences among outcome types, with no evidence of an effect for muscular force outcomes (ES0.5 = 0.05 [95%CrI: -0.25 to 0.35]) and the largest effect estimated for anaerobic outcomes (ES0.5 = 0.57 [95%CrI: 0.33 to 0.86]). Additionally, moderation effects were identified for intervention duration, sprint length, and the number sprints performed per session, with larger effects obtained for greater values of each moderator. Many positive outliers were identified with additional evidence of extensive small study effects. Conclusion:This meta-analysis demonstrates that short-term SIT interventions are effective for developing small to moderate improvements in a range of physical performance outcomes across the aerobic to anaerobic spectrum. However, extensive small study effects, likely influenced by researchers analysing many outcomes, suggests potential overestimation of reported effects. It is recommended that future research analyse a smaller nu...