A permeabilized cell model for studying cell division: a comparison of anaphase chromosome movement and cleavage furrow constriction in lysed PtK1 cells.

After lysis in a Brij 58-polyethylene glycol medium, PtK1 cells are permeable to small molecules, such as erythrosin B, and to proteins, such as rhodamine-labeled FAB, myosin subfragment-1, and tubulin. Holes are present in the plasma membrane, and the mitochondria are swollen and distorted, but other membrane-bounded organelles of the lysed cell model are not noticeably altered. After lysis, the mitotic apparatus is functional; chromosomes move poleward and the spindle elongates. Cells lysed while in cytokinesis will continue to divide for several minutes. Addition of crude tubulin extracts, MAP-free tubulin, or taxol to the lysis medium retards anaphase chromosome movements but does not affect cleavage. On the other hand, N-ethylmaleimide-modified myosin subfragment-1, phalloidin, and cytochalasin B inhibit cleavage but have no effect on anaphase chromosome movements under identical lysis conditions. These results suggest that actomyosin plays no functional role in anaphase chromosome movement in mammalian tissue culture cells and that microtubule depolymerization is a rate-limiting step for chromosome-to-pole movements

The thermoregulatory and thermal responses of individuals with a spinal cord injury during exercise, acclimation and by using cooling strategies-A systematic review

In individuals with a spinal cord injury thermoregulatory mechanisms are fully or partially interrupted. This could lead to exercise-induced hyperthermia in temperate conditions which can be even more distinct in hot conditions. Hyperthermia has been suggested to impair physiological mechanisms in athletes, which could negatively influence physical performance and subjective well-being or cause mild to severe health issues. The aim was to evaluate the literature on the thermoregulatory and thermal responses of individuals with a spinal cord injury during exercise in temperate and hot conditions taking the effects of cooling techniques and heat acclimation into account. Two electronic databases, PubMed and Web of Science were searched. Studies were eligible if they observed the influence of exercise on various thermoregulatory parameters (e.g., core and skin temperature, sweat rate, thermal sensation) in individuals with a spinal cord injury. In total 32 articles were included of which 26 were of strong, 3 of moderate and 3 of weak quality. Individuals with a high lesion level, especially those with a tetraplegia, reached a higher core and skin temperature with a lower sweat rate. The use of cooling techniques before and during exercise can positively affect the burden of the impaired thermoregulatory system in all individuals with a spinal cord injury. Due to the absence of normal thermoregulatory abilities, individuals with a high-level spinal cord injury need special attention when they are exercising in temperate and hot conditions to prevent them from potential heat related issues. The use of cooling techniques can reduce this risk. [Abstract copyright: Copyright © 2021 Grossmann, Flueck, Perret, Meeusen and Roelands.

Heart rate responses and technical-tactical aspects of official 5-a-side youth soccer matches played on soil and artificial turf.

Using a randomized crossover design, this study aimed to compare the heart rate (HR) responses and match analysis parameters (i.e., type of action; the number of players involved in an action; the number of passes performed in a collective action; precision of the shots; lost balls; ball interceptions; dribblings; and tackles) of official 5-a-side youth male soccer matches played over 2 pitch surface (i.e., clay vs. artificial turf) conditions. Twenty-two young male soccer players (age 8.3 6 0.4 years) engaged in 2 consecutive 15-minute periods in each experimental condition. During the match, 53% of HR responses exceeded 85% of the individual HRpeak. No difference emerged between both pitch surfaces and match periods for HR and match analysis indicators. The two 15-minute periods resulted in being appropriate for 8-year-old players, in resembling the intensity of play and the intermittent nature of adult soccer. The similar HR responses and technical-tactical patterns observed on the 2 surfaces indicate that youth match play is not affected by differences in pitch surface. To support the development of individual and team skills of young soccer players, coaches are advised to prioritize game knowledge based on divergent thinking and experience, rather than traditional teaching based on instructions

Production of monoclonal antibodies reactive with ovine eosinophils

<p>Abstract</p> <p>Background</p> <p>There is strong evidence implicating eosinophils in host defence against parasites as well as allergic disease pathologies. However, a lack of reagents such as monoclonal antibodies (mAbs) specific for eosinophils has made it difficult to confirm the functional role of eosinophils in such disease conditions. Using an established mammary model of allergic inflammation in sheep, large numbers of inflammatory cells enriched for eosinophils were collected from parasite-stimulated mammary glands and used for the generation of mAbs against ovine eosinophils.</p> <p>Results</p> <p>A panel of mAbs was raised against ovine eosinophils of which two were shown to be highly specific for eosinophils. The reactivity of mAbs 3.252 and 1.2 identified eosinophils from various cell and tissue preparations with no detectable reactivity on cells of myeloid or lymphoid lineage, tissue mast cells, dendritic cells, epithelial cells or other connective tissues. Two other mAbs generated in this study (mAbs 4.4 and 4.10) were found to have reactivity for both eosinophils and neutrophils.</p> <p>Conclusion</p> <p>This study describes the production of new reagents to identify eosinophils (as well as granulocytes) in sheep that will be useful in studying the role of eosinophils in disease pathologies in parasite and allergy models.</p

Diagnosing overtraining in athletes using the two-bout exercise protocol

Objective: In this work, whether a two-bout exercise protocol can be used to make an objective, immediately available distinction between non-functional over reaching (NFO) and overtraining syndrome (OTS) was studied. Design: Underperforming athletes who were diagnosed with the suspicion of NFO or OTS were included in the study. Recovery of the athletes was monitored by a sports physician to retrospectively distinguish NFO from OTS. Setting: Sports medicine laboratory Participants: The protocol was started and completed by 10 underperforming athletes. NFO was retrospectively diagnosed in five athletes, and OTS was diagnosed in five athletes. Interventions: A two-bout maximal exercise protocol was used to measure physical performance and stressinduced hormonal reactions. Main outcome measurements: Exercise duration, heart rate and blood lactate concentration were measured at the end of both exercise tests. Venous concentrations cortisol, adrenocorticotrophic hormone (ACTH), prolactin and growth hormone were measured both before and after both exercise tests. Results: Maximal blood lactate concentration was lower in OTS compared with NFO, while resting concentrations of cortisol, ACTH and prolactin concentrations were higher. However, sensitivity of these measures was low. The ACTH and prolactin reactions to the second exercise bout were much higher in NFO athletes compared with OTS and showed the highest sensitivity for making the distinction. Conclusions: NFO might be distinguished from OTS based on ACTH and prolactin reactions to a two-bout exercise protocol. This protocol could be a useful tool for diagnosing NFO and OTS; however, more data should be collected before this test can be used as the gold standard

Cycling exposure and infrastructural correlates in a Flemish adolescent population

Introduction: Infrastructure adjusted to cyclists can be used as a tool to reduce cycling crashes and injuries. To increase cycling frequency and safety, a population's cycling exposure to different infrastructure needs to be known. Since cycling behavior of adolescents cannot be compared to adults, the objective of this study is to describe the cycling exposure and the characteristics of routes used by adolescents for bicycle commuting. Methods: We used an online travel diary to collect bicycle route information and an exposure matrix to collect cycling frequency data. Data were collected in Flanders (Belgium) from an adolescent population (15-18 years). Results: From the 1345 participating adolescents, 47% used their bicycle at least once a week. Infrastructural correlates were based on 467,000 km of cycled roads with a mean trip distance of 5.7 +/- 4.5 km; 91% of cycling exposure is on infrastructure with speed limits of 50 km/h or more and 32.7% on dedicated cycle lanes. Lower motorized traffic density was related to higher odds of daily bicycle commuting. Higher traffic densities or speed limits were related to lower odds of daily bicycle commuting, but this relationship disappeared after adjusting for presence of a dedicated cycle lane. Conclusions: Many adolescents who commute by bicycle cycle along streets with high speed limits and no dedicated cycle lanes probably because of the low motorized traffic densities on these roads. Adolescents should avoid roads without dedicated cycling infrastructure and high speed limits since these roads have been identified as high risk. The results are region specific and therefore this study should be replicated in other contexts