4 research outputs found
The reliability of dual-energy X-ray absorptiometry measurements of bone mineral density in the metatarsals
Correlation of MRI Grading of Bone Stress Injuries With Clinical Risk Factors and Return to Play
BackgroundBone stress injuries are common in track and field athletes. Knowledge of risk factors and correlation of these to magnetic resonance imaging (MRI) grading could be helpful in determining recovery time.PurposeTo examine the relationships between MRI grading of bone stress injuries with clinical risk factors and time to return to sport in collegiate track and field athletes.Study designCohort study (prognosis); Level of evidence, 2.MethodsA total of 211 male and female collegiate track and field and cross-country athletes were followed prospectively through their competitive seasons. All athletes had preparticipation history, physical examination, and anthropometric measurements obtained annually. An additional questionnaire was completed regarding nutritional behaviors, menstrual patterns, and prior injuries, as well as a 3-day diet record. Dual-energy X-ray absorptiometry was performed at baseline and each year of participation in the study. Athletes with clinical evidence of bone stress injuries had plain radiographs. If radiograph findings were negative, MRI was performed. Bone stress injuries were evaluated by 2 independent radiologists utilizing an MRI grading system. The MRI grading and risk factors were evaluated to identify predictors of time to return to sport.ResultsThirty-four of the athletes (12 men, 22 women) sustained 61 bone stress injuries during the 5-year study period. The mean prospective assessment for participants was 2.7 years. In the multiple regression model, MRI grade and total-body bone mineral density (BMD) emerged as significant and independent predictors of time to return to sport. Specifically, the higher the MRI grade (P = .004) and lower the BMD (P = .030), the longer the recovery time. Location of the bone injury at predominantly trabecular sites of the femoral neck, pubic bone, and sacrum was also associated with a prolonged time to return to sport. Female athletes with oligomenorrhea and amenorrhea had bone stress injuries of higher MRI grades compared with eumenorrheic athletes (P = .009).ConclusionHigher MRI grade, lower BMD, and skeletal sites of predominant trabecular bone structures were associated with a delayed recovery of bone stress injuries in track and field athletes. Knowledge of these risk factors, as well as nutritional and menstrual factors, can be clinically useful in determining injury severity and time to return to sport
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Recurrent emergence of SARS-CoV-2 spike deletion H69/V70 and its role in the Alpha variant B.1.1.7
We report severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike ΔH69/V70 in multiple independent lineages, often occurring after acquisition of receptor binding motif replacements such as N439K and Y453F, known to increase binding affinity to the ACE2 receptor and confer antibody escape. In vitro, we show that, although ΔH69/V70 itself is not an antibody evasion mechanism, it increases infectivity associated with enhanced incorporation of cleaved spike into virions. ΔH69/V70 is able to partially rescue infectivity of spike proteins that have acquired N439K and Y453F escape mutations by increased spike incorporation. In addition, replacement of the H69 and V70 residues in the Alpha variant B.1.1.7 spike (where ΔH69/V70 occurs naturally) impairs spike incorporation and entry efficiency of the B.1.1.7 spike pseudotyped virus. Alpha variant B.1.1.7 spike mediates faster kinetics of cell-cell fusion than wild-type Wuhan-1 D614G, dependent on ΔH69/V70. Therefore, as ΔH69/V70 compensates for immune escape mutations that impair infectivity, continued surveillance for deletions with functional effects is warranted