Proteomic Discovery of Noninvasive Biomarkers Associated With Sport-Related Concussions.

BACKGROUND AND OBJECTIVES: Sport-related concussions affect millions of individuals across the United States each year, and current techniques to diagnose and monitor them rely largely on subjective measures. Our goal was to discover and validate objective, quantifiable noninvasive biomarkers with the potential to be used in sport-related concussion diagnosis. METHODS: Urine samples from a convenience series of healthy control collegiate athletes who had not sustained a concussion and athletes who sustained a concussion as diagnosed by a sports medicine physician within 7 days were collected prospectively and studied. Participants also completed an instrumented single-task gait analysis as a functional measure. Participants were recruited from a single collegiate athletic program and were ≥18 years of age and were excluded if they had a concomitant injury, active psychiatric conditions, or preexisting neurologic disorders. Using Tandem Mass Tags (TMT) mass spectroscopy and ELISA, we identified and validated urinary biomarkers of concussion. RESULTS: Forty-eight control and 47 age- and sex-matched athletes with concussion were included in the study (51.6% female, 48.4% male, average age 19.6 years). Participants represented both contact and noncontact sports. All but 1 of the postconcussion participants reported experiencing symptoms at the time of data collection. Insulin-like growth factor 1 (IGF-1) and IGF binding protein 5 (IGFBP5) were downregulated in the urine of athletes with concussions compared to healthy controls. Multivariable risk algorithms developed to predict the probability of sport-related concussion showed that IGF-1 multiplexed with single-task gait velocity predicts concussion risk across a range of postinjury time points (area under the curve [AUC] 0.786, 95% confidence interval [CI] 0.690-0.884). When IGF-1 and IGFBP5 are multiplexed with single-task gait velocity, they accurately distinguish between healthy controls and individuals with concussion at acute time points (AUC 0.835, 95% CI 0.701-0.968, p < 0.001). DISCUSSION: These noninvasive biomarkers, discovered in an objective and validated manner, may be useful in diagnosing and monitoring sport-related concussions in both acute phases of injury and several days after injury. TRIAL REGISTRATION INFORMATION: ClinicalTrials.gov Identifier: NCT02354469 (submitted February 2015, first patient enrolled August 2015). CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that urinary IGF-1 and IGFBP5 multiplexed with single-task gait velocity may be useful in diagnosing sport-related concussion.

Study of Concussion in Rugby Union through MicroRNAs (SCRUM): a study protocol of a prospective, observational cohort study.

INTRODUCTION: The diagnosis of mild traumatic brain injury or sports-related concussion is a challenge for all clinicians, players, coaches and parents involved in contact sports. Currently, there is no validated objective biomarker available to assess the presence or severity of concussion in sport, and so it is necessary to rely on subjective measures like self-reporting of symptoms which depend on the cooperation of the athlete. There is a significant health risk associated with repetitive injury if the diagnosis is missed, and so there is great value in an objective biomarker to assist diagnostic and prognostic decisions. OBJECTIVE: To establish a panel of non-invasive MicroRNA biomarkers in urine and saliva for the rapid diagnosis of sports-related concussion and investigate the kinetics and clinical utility of these biomarkers in assisting diagnostic, prognostic and return-to-play decisions. METHODS AND ANALYSIS: Observational, prospective, multicentre cohort study recruiting between the 2017-2018 and 2018-2019 Rugby Union seasons. Professional rugby players in the two highest tiers of senior professional domestic rugby competition in England will be recruited prospectively to the study. During the season, three groups will be identified: athletes entering the World Rugby Head Injury Assessment (HIA) protocol, uninjured control athletes and control athletes with musculoskeletal injuries. Saliva and urine will be collected from these athletes at multiple timepoints, coinciding with key times in the HIA protocol and return-to-play process. ETHICS AND DISSEMINATION: Ethics approval has been obtained. The compiled and analysed results will be presented at national and international conferences concerning the care of patients with traumatic brain injury. Results will also be submitted for peer review and publication in the subject journals/literature.

Impact-induced muscle damage and urinary pterins in professional rugby: 7,8-dihydroneopterin oxidation by myoglobin.

Muscle damage caused through impacts in rugby union is known to increase oxidative stress and inflammation. Pterins have been used clinically as markers of oxidative stress, inflammation, and neurotransmitter synthesis. This study investigates the release of myoglobin from muscle tissue due to force-related impacts and how it is related to the subsequent oxidation of 7,8-dihydroneopterin to specific pterins. Effects of iron and myoglobin on 7,8-dihydroneopterin oxidation were examined in vitro via strong cation-exchange high-performance liquid chromatography (SCX-HPLC) analysis of neopterin, xanthopterin, and 7,8-dihydroxanthopterin. Urine samples were collected from 25 professional rugby players pre and post four games and analyzed for myoglobin by enzyme-linked immunosorbent assay, and 7,8-dihydroneopterin oxidation products by HPLC. Iron and myoglobin oxidized 7,8-dihydroneopterin to neopterin, xanthopterin, and 7,8-dihydroxanthopterin at concentrations at or above 10 µM and 50 µg/mL, respectively. All four games showed significant increases in myoglobin, neopterin, total neopterin, biopterin, and total biopterin, which correlated between each variable (P < 0.05). Myoglobin and iron facilitate 7,8-dihydroneopterin oxidation to neopterin and xanthopterin. In vivo delocalization of myoglobin due to muscle damage may contribute to oxidative stress and inflammation after rugby. Increased concentrations of biopterin and total biopterin may indicate production of nitric oxide and monoamine neurotransmitters in response to the physical stress.

Urinary changes in ultra long-distance marathon runners.

The urine of 45 athletes, male and female, were studied after completing an ultra long-distance marathon race. Of these athletes, 24.4% were found on screening to have red blood cells in the urine. The urinary mean corpuscular volume (MCV) of red cells was used in an attempt to differentiate between lower and upper urinary tract haematuria. With the exception of 1 athlete, the red cells were not dysmorphic and had an MCV greater than 72 fl. This suggested that the haematuria had an origin from the lower urinary tract. The urinary changes disappeared within 7 days. No definite residual renal damage could be established.

Sports hematuria.

Strenuous exercise makes extraordinary demands. The transition from rest to intensive physical activity can cause pathological changes in various organs, particularly in the urinary tract. Hematuria (microscopic or macroscopic) is one of the abnormalities commonly found after sports activity. This phenomenon can occur in noncontact sports (such as rowing, running and swimming) as well as in contact sports (boxing, football and so forth). The pathophysiology can be either traumatic or nontraumatic. Renal trauma and/or bladder injury due to repeated impact of the posterior bladder wall against the bladder base can cause vascular lesions and consequently hematuria. There are 2 mechanisms of nontraumatic injury. 1) Vasoconstriction of the splanchnic and renal vessels occurs during exercise in order that blood can be redistributed to the contracting skeletal muscles, thus causing hypoxic damage to the nephron. This results in increased glomerular permeability which would favor increased excretion of erythrocytes and protein into the urine. 2) A relatively more marked constriction of the efferent glomerular arterioli results in an increased filtration pressure, which favors increased excretion of protein and red blood cells into the urine. It must be noted that sports hematuria differs from other conditions that may cause reddish discoloration of the urine due to physical exercise, such as march hemoglobinuria and exercise myoglobinuria. In the latter 2 abnormalities there is excretion of hemoglobin and myoglobin molecules in the urine and not whole blood or intact red blood cells. Sports hematuria usually has a benign self-limited course. However, coexisting urinary tract pathological conditions should be excluded carefully.