Influence of endothelium on the membrane-stabilizing effect of calcium

Background: A decrease in membrane permeability to calcium ions, caused by increased extracellular calcium concentration is referred to as membrane-stabilization. There is a paucity of information on the role of vascular endothelium in the membrane-stabilizing effect of Ca2+ ions. The goal of the present study was to examine the influence of the endothelium on the membrane-stabilizing effect of Ca2+ ions in rabbit aortic smooth muscle. Methods: Isometric contractions of 2mm ring segments of rabbit aorta, placed in 20ml organ baths containing physiological salt solution (PSS) and bubbled with 95% O2, 5% CO2 gas mixture at 37oC and pH 7.4 were examined. The magnitude of the relaxation responses induced by increasing extracellular Ca2+ concentration from 5.0 to 25mM in phenylephrine pre-contracted rings was taken as an indirect indicator of the membrane-stabilizing effect of Ca2+. The relaxation responses induced by 25mM Ca2+ were estimated in endothelium-intact, endothelium-denuded rings as well as following exposure to 10-6M methylene blue. Results: In all experiments, an increase in [Ca2+]o (low bicarbonate PSS) from 5.0 to 25.0mM in rings with intact endothelium resulted in relaxation responses. These relaxation responses were attenuated in endothelium-denuded rings as well as following exposure to methylene blue. Conclusion: The results show that relaxation responses induced by high Ca2+ due to membrane stabilization is endothelium-dependent.Keywords: Calcium, rabbit aorta, Vascular smooth muscle, Membrane stabilization,Endothelium, methylene blue, Guanylate cyclas

COVID-19 Pandemic: Potential Impact of Lockdown in Sub-Saharan Africa

The COVID-19 lockdown approach in sub-Saharan Africa countries may not be as beneficial as intended due to the current employment, housing and health infrastructure challenges. Hence other infection prevention and control might need to be considered

Injuries in male and female semi-professional football (soccer) players in Nigeria: prospective study of a National Tournament

BACKGROUND: Research on the epidemiology of football injuries in Africa is very sparse despite its importance for injury prevention planning in a continent with limited sports medicine resources. The vast majority of studies available in literature were conducted in Europe and only a very few studies have prospectively reported the pattern of football injury in Africa. The purpose of this study was to evaluate the incidence and pattern of injuries in a cohort of male and female semi-professional football players in Nigeria. METHODS: A prospective cohort design was conducted, in which a total of 756 players with an age range of 18–32 years (356 males and 300 females) from 22 different teams (12 male and 10 female teams), were prospectively followed in a National Football Tournament. Physiotherapists recorded team exposure and injuries. Injuries were documented using the consensus protocol for data collection in studies relating to football injury surveillance. RESULTS: An overall incidence of 113.4 injuries/1000 h (95% CI 93.7–136.0) equivalent to 3.7 injuries/match and time-loss incidence of 15.6 injuries/1000 h were recorded for male players and 65.9 injuries/1000 h (95% CI 48.9–86.8) equivalent to 2.2 injuries/match and time-loss incidence of 7.9 injuries/1000 h were recorded for female players. Male players had a significantly higher risk of injuries [IRR = 1.72 (95% CI 1.23–2.45)]. Injuries mostly affected the lower extremity for both genders (n = 81, 70% and n = 31, 62% for males and females respectively). Lower leg contusion (n = 22, 19%) and knee sprain (n = 9, 18%) were the most common specific injury types for male and female players respectively. Most of the injuries were as a result of contact with another player (n = 102, 88%—males; n = 48, 96%—females). Time-loss injuries were mostly estimated as minimal (n = 11, 69%) for male players and severe (n = 4, 66%) for female players. CONCLUSION: The overall incidence of injuries among Nigerian semi-professional football players is high but most of the injuries do not result in time-loss. Pattern of injuries is mostly consistent with previous studies. More prospective studies are needed to establish injury prevention initiatives among African players

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe