Start-up propulsion biomechanics changes with fatiguing activity in persons with spinal cord injury

Objective: Shoulder pathology is a common condition in wheelchair users that can considerably impact quality of life. Shoulder muscles are prone to fatigue, but it is unclear how fatigue affects start-up propulsion biomechanics. This study determines acute changes in start-up wheelchair propulsion biomechanics at the end of a fatiguing propulsion protocol.

Design: Quasi-experimental one-group pretest-postest design.

Setting: Biomechanics laboratory. Participants: Twenty-six wheelchair users with spinal cord injury (age: 35.5?±?9.8 years, sex: 73% males and 73% with a paraplegia).

Interventions: Protocol of 15 min including maximum voluntary propulsion, right- and left turns, full stops, start-up propulsion, and rests.

Outcome measures: Maximum resultant force, maximum rate of rise of applied force, mean velocity, mean fraction of effective force, and mean contact time at the beginning and end of the protocol during start-up propulsion.

Results: There was a significant reduction in maximum resultant force (P?<?0.001) and mean velocity (P?<?0.001) at the end of the protocol. Also, contact time was reduced in the first stroke of start-up propulsion (P?<?0.001). Finally, propelling with a shorter contact time was associated with a greater reduction in performance (maximum velocity) at the end of the protocol.

Conclusion: There are clear changes in overground propulsion biomechanics at the end of a fatiguing propulsion protocol. While reduced forces could protect the shoulder, these reduced forces come with shorter contact times and lower velocity. Investigating changes in start-up propulsion biomechanics with fatigue could provide insight into injury risk.     

角膜内皮移植术后早期玻璃酸钠对泪膜及角膜上皮细胞再生的作用

目的　研究1 g·L^-1和3 g·L^-1玻璃酸钠（hyaluronate，HA）滴眼液对角膜内皮移植术后早期泪膜及角膜上皮细胞再生的作用。方法　选择2017年9月至2018年2月在北京大学第三医院行角膜内皮移植术的患者60例（60眼），随机分成1 g·L^-1HA组和3 g·L^-1HA组，每组各30例，观察标准干眼评估问卷（SPEED）评分、结膜角膜染色评分（OSS）、泪膜破裂时间（TBUT）、角膜上皮缺损范围，进行激光共聚焦显微镜检查。比较不同时间点组间、组内各指标差异。结果　SPEED评分:各时间点两组间比较差异均无统计学意义（均为P>0.05）。组内比较:两组组内术后7 d、14 d、28 d均低于前一时间点（均为P=0.000），余相邻时间点两两比较差异均无统计学意义（均为P>0.05）。TBUT:术后7 d、14 d、28 d 3 g·L^-1HA组均显著高于1 g·L^-1HA组（均为P<0.05），而术前组间差异不显著；组内比较:1 g·L^-1 HA组后一时间点较前一时间点、3 g·L^-1HA组术后7 d较术前均显著延长(均为P<0.05)，而3 g·L^-1HA组术后14 d、28 d与前一时间点差异均无统计学意义（均为P>0.05）。 OSS评分:术前及术后1 d、3 d两组间比较差异均无统计学意义（均为P>0.05），术后7 d、14 d、28 d 3 g·L^-1HA组均显著低于1 g·L^-1HA组（均为P<0.05）；组内比较:两组术后1 d OSS评分均显著高于术前（均为P=0.000），其余时间点两组均低于前一时间点（均为P=0.000）。角膜上皮缺损范围:术后1 d 两组间比较差异均无统计学意义（均为P>0.05），术后3 d、7 d 两组间比较，以及两组组内与前一时间点比较差异均有统计学意义（均为P<0.05）。角膜基底细胞密度:术前、术后28 d两组间比较，以及1 g·L^-1HA组组内术前与术后28 d比较差异均无统计学意义（均为P>0.05），而3 g·L^-1 HA组术后28 d显著低于术前（P=0.002）。结论　HA可以有效改善角膜内皮移植术后早期泪膜状态并促进角膜上皮细胞再生，存在浓度依赖性。     

Association of meibomian gland architecture and body mass index in a pediatric population

PurposeTo determine if meibomian gland architecture in a pediatric population is impacted by body mass index (BMI).MethodsProspective evaluation of 175 eyes of 175 pediatric patients from two clinics. Demographic and clinical information were reviewed. Symptoms of dry eye were assessed with the Standard Patient Evaluation of Eye Dryness (SPEED) questionnaire. Meibography was performed and grading of images was performed by a masked rater using a previously validated 5-point meiboscale (0–4) for gland atrophy and a 3-point score (0–2) for gland tortuosity.Results175 eyes of 175 participants aged 4–17 years (11.6 ± 3.7 years) were imaged. The mean meiboscore was 0.82 ± 0.94 (range 0–4) and the mean gland tortuosity score was 0.53 ± 0.70 (range 0–2). Ninety-six patients (56%) showed evidence of gland atrophy (meiboscore greater than 0) and the majority of patients (n=50, 29%) had a gland tortuosity score of 1. The mean BMI was 20.5 ± 4.86 kg/m² with 39.4% of patients (n = 69) above the 85th percentile. BMI percentile was not found to be a significant predictor of a meiboscore greater than 0 (odds ratio (OR) 1.004 95% confidence interval (CI) (0.99–1.10, p = 0.41). However, BMI percentile was found to be a significant predictor of gland tortuosity score (OR 1.01 95% CI (1.00–1.02), p = 0.02). Patients with BMI percentiles between 41 and 60 were 3.79 times more likely to have a gland tortuosity score of greater than 0 than patients with BMI percentiles between 0 and 20 (OR 3.789 CI (1.17–12.24)). No significant associations were found between age, race, or sex and meiboscore or tortuosity. There was a trend towards reduction in lipid layer thickness with increasing BMI percentile (p = 0.028, r² = 0.04).ConclusionIn this pediatric population, there was an association between meibomian gland tortuosity and higher percentiles of BMI. Future studies are needed to elucidate the pathogenesis of meibomian gland tortuosity and atrophy in pediatric patients.     

Epidemiology of isolated adult lower limb burns over 15 years with a focus on preventable work-related injuries

Our aim was to describe the epidemiology of isolated adult lower limb burns presenting to the Pinderfields Regional Burns Centre, Wakefield, United Kingdom between 2003 and 2018. Data was obtained using our local records of the international Burn Injury Database (iBID).6059 patients were treated in our department during this period. 18.7% presented with isolated lower limb burns (n = 1133). 65.4% of patients were male (n = 741). Scald was the most common mechanism of injury. Work-related burns accounted for 23.4% of the injuries (n = 265).36% of patients were admitted (n = 408), and 11.7% underwent surgical intervention (n = 133).Isolated lower limb burns are common in patients in the working age group. Work-related injuries are preventable. Targeted education to highlight the risks, reduce the incidence, and improve awareness of first aid measures are recommended.     

Impact of the COVID-19 lockdown on digital device-related ocular health

Purpose:Since the declaration of the lockdown due to COVID-19, the usage of digital devices has gone up across the globe, resulting in a challenge for the visual systems of all ages. The purpose of this study is to assess the impact of the lockdown on digital device usage, and consequently, the ocular surface health implications and circadian rhythm abnormalities related to digital eye strain.Methods:An open online survey was sent through various social media platforms and was open for a period of 2 weeks.Results:A total of 407 usable responses were obtained; the average age of respondents was 27.4 years. Typically, 93.6% of respondents reported an increase in their screen time since the lockdown was declared. The average increase in digital device usage was calculated at about 4.8 ± 2.8 h per day. The total usage per day was found to be 8.65 ± 3.74 hours. Sleep disturbances have been reported by 62.4% of people. Typically, 95.8% of respondents had experienced at least one symptom related to digital device usage, and 56.5% said that the frequency and intensity of these symptoms increased since the lockdown was declared.Conclusion:The study highlighted the drastic increase in use of digital devices after the initiation of the COVID-19 lockdown, and along with it, the slow deterioration of ocular health across all age groups. Awareness about prevention of digital eye strain should be stressed, and going forward, measures to bring these adverse effects to a minimum should be explored.     

儿童期创伤应对方式自动思维与大学生抑郁特质间的关系

目的探讨儿童期创伤与抑郁特质之间的中介和调节机制,为开展相关研究和干预提供参考。方法2017-2018年采用整群抽样的方法,抽取湖南某高校大一年级2 786名学生完成儿童期创伤问卷、状态特质抑郁问卷、自动思维问卷和特质应对方式问卷的调查。结果儿童期创伤、自动思维和消极应对对抑郁特质起正向的预测作用,积极应对对抑郁特质起负向的预测作用(β值分别为0.12,0.43,0.14,-0.33,P值均<0.05)。自动思维中介儿童期创伤与抑郁特质之间的关系(Bootstrapping法的95%CI为0.03~0.06)。消极应对分别调节了儿童期创伤与自动思维和儿童期创伤与抑郁特质之间的关系(P值均<0.05)。结论儿童期创伤影响抑郁特质,其关系受到应对方式和自动思维的影响。     

Arterial endofibrosis in endurance athletes: Prospective comparison of the diagnostic accuracy of intra-arterial digital subtraction angiography and computed tomography angiography

PurposeTo prospectively compare the diagnostic capabilities of computed tomography angiography (CTA) to those of digital subtraction angiography (DSA) in endurance athletes with suspicion of arterial endofibrosis.Materials and methodsForty-five athletes (39 men, 6 women; median age: 30 years, interquartile range: 23–42 years) prospectively underwent DSA and CTA without (n = 5) or with (n = 40) electrocardiogram gating. DSA was interpreted by a single expert (experience of 15 years). CTA was independently interpreted by three other readers (experience of 5–8 years). Readers assessed the presence and degree of stenoses on iliac and femoral arteries and the overall diagnosis (negative, uncertain, positive) of endofibrosis at the limb level. Sensitivities and specificities of DSA and CTA were estimated at the limb level using histological findings and long-term follow-up as reference, and compared using the McNemar test.ResultsFor diagnosing and quantifying stenoses, concordance between DSA and CTA was moderate-to-good for common and external iliac arteries, moderate for lateral circumflex arteries and poor-to-moderate for the other branches of the deep femoral artery. It was good for all readers for the overall diagnosis of endofibrosis. After long-term follow-up (median, 95 months; interquartile range: 7–109 months), DSA sensitivity and specificity were respectively 88.6% (39/44; 95% confidence interval [CI]: 76–95%) and 75% (24/32; 95% CI: 57.9–86.7%); CTA sensitivity and specificity were respectively 88.6% (39/44; 95% CI: 76–95%; P > 0.99) and 84.4% (27/32; 95% CI: 68.2–93.1%; P = 0.51), 86.3% (38/44; 95% CI: 73.3–93.6%; P > 0.99) and 75% (24/32; 95% CI: 57.9–86.7%; P > 0.99), and 84.1% (37/44; 95% CI: 70.6–92.1%; P = 0.68) and 75% (24/32; 95% CI: 57.9–86.7%; P > 0.99) for the three readers.ConclusionCTA shows performances similar to those of DSA in predicting the long-term diagnosis of endofibrosis in endurance athletes with suggestive symptoms.