Tackle injury epidemiology and performance in rugby league - narrative synthesis

Background

In rugby league (RL), the ability to repeatedly engage in the tackle, whether as a ball carrier or tackler, is essential for team success and player performance. It is also the leading cause of injury, with over 90% of total injuries occurring during the tackle in professional and amateur cohorts. To effectively reduce the risk of injury and optimise performance, establishing the extent of the 'problem', through injury surveillance or descriptive performance studies is required.

Objective

The purpose of this narrative synthesis was to systematically search and synthesise tackle injury epidemiology and tackle performance frequency in RL. To achieve this objective, a systematic review was conducted.

Methods

The search was limited to English-only articles published between January 1995 and October 2018. Based on the search criteria, a total of 53 studies were found: 32 focused on tackle injury epidemiology (nine cases studies) and 21 focused on tackle frequency.

Results

In general, over 600 tackles may occur during an RL match. Tackle injury frequencies (both overall and time-loss injuries) ranged between 47%-94% at the professional level, and between 38%-96% for the lower levels of play. A greater proportion of injuries occurring in professional RL are severe time-loss injuries when compared to lower levels of play. Most time-loss and overall injuries occur to players who are tackled, i.e., ball carriers, across all levels of play.

Conclusion

This narrative synthesis will facilitate tackle injury prevention and performance research in RL, and act as a reference document for coaches and practitioners.

Correction to: Protection against cardiac ischemia-reperfusion injury by hypothermia and by inhibition of succinate accumulation and oxidation is additive

The original version of this article unfortunately contained a mistake.

Protection against cardiac ischemia-reperfusion injury by hypothermia and by inhibition of succinate accumulation and oxidation is additive

Hypothermia induced at the onset of ischemia is a potent experimental cardioprotective strategy for myocardial infarction. The aim of our study was to determine whether the beneficial effects of hypothermia may be due to decreasing mitochondria-mediated mechanisms of damage that contribute to the pathophysiology of ischemia/reperfusion injury. New Zealand male rabbits were submitted to 30 min of myocardial ischemia with hypothermia (32 °C) induced by total liquid ventilation (TLV). Hypothermia was applied during ischemia alone (TLV group), during ischemia and reperfusion (TLV-IR group) and normothermia (Control group). In all the cases, ischemia was performed by surgical ligation of the left anterior descending coronary artery and was followed by 3 h of reperfusion before assessment of infarct size. In a parallel study, male C57BL6/J mice underwent 30 min myocardial ischemia followed by reperfusion under either normothermia (37 °C) or conventionally induced hypothermia (32 °C). In both the models, the levels of the citric acid cycle intermediate succinate, mitochondrial complex I activity were assessed at various times. The benefit of hypothermia during ischemia on infarct size was compared to inhibition of succinate accumulation and oxidation by the complex II inhibitor malonate, applied as the pro-drug dimethyl malonate under either normothermic or hypothermic conditions. Hypothermia during ischemia was cardioprotective, even when followed by normothermic reperfusion. Hypothermia during ischemia only, or during both, ischemia and reperfusion, significantly reduced infarct size (2.8 ± 0.6%, 24.2 ± 3.0% and 49.6 ± 2.6% of the area at risk, for TLV-IR, TLV and Control groups, respectively). The significant reduction of infarct size by hypothermia was neither associated with a decrease in ischemic myocardial succinate accumulation, nor with a change in its rate of oxidation at reperfusion. Similarly, dimethyl malonate infusion and hypothermia during ischemia additively reduced infarct size (4.8 ± 2.2% of risk zone) as compared to either strategy alone. Hypothermic cardioprotection is neither dependent on the inhibition of succinate accumulation during ischemia, nor of its rapid oxidation at reperfusion. The additive effect of hypothermia and dimethyl malonate on infarct size shows that they are protective by distinct mechanisms and also suggests that combining these different therapeutic approaches could further protect against ischemia/reperfusion injury during acute myocardial infarction.

Phospholipase A2 of Microbiota as Pathogenetic Determinant to Induce Inflammatory States in Ulcerative Colitis: Therapeutic Implications of Phospholipase A2 Inhibitors

Background

Attack by commensal microbiota is one component of induction of inflammatory episodes in ulcerative colitis (UC). In UC, the mucus layer is intrinsically devoid of phosphatidylcholine (PC) resulting in low hydrophobicity which facilitates bacterial invasion. Colonic ectophospholipase-carrying bacterial strains are likely candidates to further thinning the PC mucus barrier and to precipitate inflammatory episodes.

Objective

To evaluate the effect of phospholipase A₂ (PLA₂) inhibitors on inflammation in a genetic UC mouse model.

Methods

As PLA₂ inhibitor, we applied the bile acid-phospholipid conjugate ursodeoxycholate-lysophosphatidylethanolamide (UDCA-LPE) or as control 5% Tween 80 by oral gavage to intestine-specific kindlin 2 knockout mice.

Results

Luminal UDCA-LPE reduced the PLA₂ activity in stool by 36 ± 8%. Concomitantly no inflammatory phenotype was observed when compared to kindlin 2^(-/-) mice not treated with UDCA-LPE. The improvement was documented in regard to stool consistency, calprotectin levels in stool, and macroscopic/endoscopic as well as histologic features of the mucosa. The pattern of colonic microbiota distribution obtained in the UC phenotype mice was reversed by UDCA-LPE to the control mice pattern.

Conclusion

The inhibition of the bacterial ectophospholipase A₂ activity improves mucosal inflammation in a genetic mouse model of UC. It is assumed that the remaining mucus PC shield is better preserved when luminal PLA₂ is suppressed.

Cellular Uptake of Gold Nanoparticles and Their Behavior as Labels for Localization Microscopy

Gold nanoparticles (GNPs) enhance the damaging absorbance effects of high-energy photons in radiation therapy by increasing the emission of Auger-photoelectrons in the nm-μm range. It has been shown that the incorporation of GNPs has a significant effect on radiosensitivity of cells and their dose-dependent clonogenic survival. One major characteristic of GNPs is also their diameter-dependent cellular uptake and retention. In this article, we show by means of an established embodiment of localization microscopy, spectral position determination microscopy (SPDM), that imaging with nanometer resolution and systematic counting of GNPs becomes feasible, because optical absorption and plasmon resonance effects result in optical blinking of GNPs at a size-dependent wavelength. To quantify cellular uptake and retention or release, SPDM with GNPs that have diameters of 10 and 25 nm was performed after 2 h and after 18 h. The uptake of the GNPs in HeLa cells was either achieved via incubation or transfection via DNA labeling. On average, the uptake by incubation after 2 h was approximately double for 10 nm GNPs as compared to 25 nm GNPs. In contrast, the uptake of 25 nm GNPs by transfection was approximately four times higher after 2 h. The spectral characteristics of the fluorescence of the GNPs seem to be environment-dependent. In contrast to fluorescent dyes that show blinking characteristics due to reversible photobleaching, the blinking of GNPs seems to be stable for long periods of time, and this facilitates their use as an appropriate dye analog for SPDM imaging.

A phase I study of tumor treating fields (TTFields) in combination with pemetrexed for pretreated advanced non-small cell lung cancer

e18500

Background: TTFields (tumor treating fields) are low intensity, intermediate frequency, alternating electric fields which slow the growth of solid tumors in-vivo, and have shown promise in pilot clinical trials in patients with advanced solid tumors. TTFields are a regional treatment which acts both by interfering with microtubules polymerization and by physical disruption of the cell structure during cytokinesis. It has been shown previously that TTFields sensitize non-small cell lung cultures to Pemetrexed. In-Vivo, TTFields did not increase pemetrexed related toxicity. Methods: A prospective trial was performed in 14, pretreated, stage IIIb-IV, NSCLC patients. Patients with brain metastases were excluded, as were patients with abnormal marrow, kidney, liver or cardiac functions. Patients with history of clinically significant arrhythmias or those having pacemakers were excluded as well. Patients received Pemetrexed 500mg/m2 IV q3w together with daily TTFields (12 h/day) using a portable medical device (NovoTTF-100L). The device generated 2 direction (AP and Lat), 150 kHz TTFields. Patients were followed every three weeks and had a lung CT every 9 weeks. The primary endpoint was the safety and tolerability of the NovoTTF-100L device in combination with pemetrexed. Results: The 14 patients received an average of 4 courses of pemetrexed (Range 1–9) and a cumulative TTFields treatment time of 182 weeks. The device was well tolerated as indicated in the device log files which showed an average daily use of 11±1 hours. There were no device-related, nor pemetrexed-related SAEs. In addition, no unexpected abnormalities were evident in the lab tests or EKGs, done every 3 weeks for all patients. There were no reports of arrhythmias. The only device related AE seen in all patients was dermatitis under the electrodes. This improved with meticulous skin care, topical steroid use and in extreme cases oral steroids. One patient (7.6%) had a CR, 1 a PR (7.6%), 9 SD (69.2%) and 3 PD (23%). 77% of patients were progression free at 12 weeks and the 6 month survival was 89%. Conclusions: TTFields are well tolerated when given together with pemetrexed. The excellent safety profile and initial efficacy results reported here justify further clinical testing.

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Oxidant tone regulates RANTES gene expression in airway epithelial cells infected with respiratory syncytial virus. Role in viral-induced interferon regulatory factor activation

Respiratory syncytial virus (RSV) produces intense pulmonary inflammation, in part, through its ability to induce chemokine synthesis in infected airway epithelial cells. RANTES (regulated upon activation, normal T-cells expressed and secreted) is a CC chemokine which recruits and activates monocytes, lymphocytes, and eosinophils, all cell types present in the lung inflammatory infiltrate induced by RSV infection. In this study we investigated the role of reactive oxygen species in the induction of RANTES gene expression in human type II alveolar epithelial cells (A549), following RSV infection. Our results indicate that RSV infection of airway epithelial cells rapidly induces reactive oxygen species production, prior to RANTES expression, as measured by oxidation of 2',7'-dichlorofluorescein. Pretreatment of airway epithelial cells with the antioxidant butylated hydroxyanisol (BHA), as well a panel of chemically unrelated antioxidants, blocks RSV-induced RANTES gene expression and protein secretion. This effect is mediated through the ability of BHA to inhibit RSV-induced interferon regulatory factor binding to the RANTES promoter interferon-stimulated responsive element, that is absolutely required for inducible RANTES promoter activation. BHA inhibits de novo interferon regulator factor (IRF)-1 and -7 gene expression and protein synthesis, and IRF-3 nuclear translocation. Together, these data indicates that a redox-sensitive pathway is involved in RSV-induced IRF activation, an event necessary for RANTES gene expression.

Inhibition of acetylcholinesterase by three new pyridinium compounds and their effect on phosphonylation of the enzyme

Three new mono-pyridinium compounds were prepared: 1-phenacyl-2-methylpyridinium chloride (1), 1-benzoylethylpyridinium chloride (2) and 1-benzoylethylpyridinium-4-aldoxime chloride (3) and assayed in vitro for their inhibitory effect on human blood acetylcholinesterase (EC 3.1.1.7, AChE). All the three compounds inhibited AChE reversibly; their binding affinity for the enzyme was compared with their protective effect (PI) on AChE phosphonylation by soman and VX. Compound 1 was found to bind to both the catalytic and the allosteric (substrate inhibition) sites of the enzyme with estimated dissociation constants of 6.9 microM (Kcat) and 27 microM (Kall), respectively. Compound 2 bound to the catalytic site with Kcat = 59 microM and compound 3 only to the allosteric site with Kall = 328 microM. PI was evaluated from phosphonylation measured in the absence and in presence of the compounds applied in a concentration corresponding to their Kcat or Kall value, and was also calculated from theoretical equations deduced from the reversible inhibition of the enzyme. Compounds 1 and 3 protected the enzyme from phosphonylation by soman and VX, whereas no protection was observed in the presence of compound 2 under the same conditions. Irrespective of the binding sites to AChE, PI for compounds 1 and 3 evaluated from phosphonylation agreed with PI calculated from reversible inhibition. Compound 3 was found to be a weak reactivator of methylphosphonylated AChE with Kr = 1.1 x 10(2) L mol-1 min-1.

Localization and characterization of white blood cell populations within the human ovary throughout the menstrual cycle and menopause

The purpose of this investigation was to localize and characterize white blood cell populations in the human ovary through its physiological life cycle. Ovaries from 30 women of reproductive age and from three post-menopausal women were embedded in paraffin or frozen. Clinical information and pathology review were used to obtain accurate menstrual cycle information and to ensure the absence of ovarian disease. Tissue sections were stained for leukocyte phenotypes and the numbers of white blood cells in the ovary were semiquantitatively assessed by two separate examiners using a 0-3 plus (+) scoring system. Our results demonstrated that macrophages and T lymphocytes were the primary immune cells of the ovary, the concentrations of which were dependent on the location and stage of development of the structures containing leukocytes. Developing follicles contained few (+) macrophages located in the theca, while atretic follicles possessed moderate (+2) numbers in the granulosa and few (+) to moderate (+2) numbers in the theca. Newly formed corpora lutea contained few (+) macrophages, while regressing corpora lutea contained abundant (+3) numbers. Human leukocyte antigen (HLA)-DR positive cells were located predominantly at sites where macrophages were present. T lymphocytes were generally not present in the developing follicle but focal, small (+) numbers were observed in blood vessels of the theca. Atretic follicles contained few (+) T lymphocytes in the granulosa and few (+) to moderate (+2) numbers in the theca. Few (+) T lymphocytes were present in new corpora lutea, while moderate (+2) to abundant (+3) numbers were present in regressing corpora lutea. T lymphocytes at all sites were UCHL1 positive. The CD4 (T helper) to CD8 (T suppressor) ration in the corpus luteum was 1:1. B-lymphocytes and natural killer cells were generally absent in the pre-menopausal ovary. The post-menopausal ovary, in contrast, only contained few (+) macrophages, T lymphocytes and natural killer cells in the stroma. In conclusion, our results indicate that the human ovary is an immunologically dynamic tissue containing activated macrophages and T lymphocytes which provide an anatomical basis for immunoendocrine interactions within the ovary.