SARS-CoV、MERS-CoV、SARS-CoV-2的基因结构特点与致病机制

高致病性冠状病毒具有高发病率、高病死率以及全球大流行等特点,严重威胁人类健康,给社会经济带来巨大挑战。目前关于高致病冠状病毒的致病机制,主要从直接细胞病变效应和间接免疫病理损伤两方面进行讨论,但具体作用基因的研究尚需进一步深入。本文从高致病性冠状病毒的基因结构特点与致病机制的相关性进行综述,为预防和治疗高致病性冠状病毒感染提供参考。     

城市社区在公共卫生管理中的干预机制构建

公共卫生管理和防控作为基础性、长期性的重大民生工程,对人民群众的身体健康、生命安全有着重要影响。社区作为社会基层,在突发公共卫生事件的防控中成为工作重心。当前城市社区在公共卫生管理和防控中还存在诸多问题,应从激发社区内生动力、精准施策、强化社区主体责任、加强信息化建设、科学舆情疏导等方面着力实施,不断提升社区干预在突发公共卫生事件防控中的治理水平。     

COVID-19对学术交流的影响及学术出版机构的应对举措

【目的】 研究COVID-19疫情暴发给学术交流及学术出版带来的深远影响。【方法】 利用文献调研法和案例分析法挖掘COVID-19疫情带来的学术环境变化,并探讨学术出版的整体变化趋势和国内外出版机构的应对方式。【结果】 COVID-19疫情改变了当前的学术交流环境:加速推进开放科学进程,快速传播的预出版模式受到青睐,开放评审促进快速学术交流,多项基金项目助力COVID-19科学研究,中国科研人员应对COVID-19反应积极而迅速。出版机构顺应学术出版的整体趋势,为科学共同体提供大量免费服务,扩大知识服务的目标群体,提供海量知识及COVID-19快速发表通道,我国出版机构应对COVID-19也采取了大量积极举措。【结论】 国内外出版机构应对突发事件时应建立学术出版应急机制,增强知识服务能力,促进知识创新及传播,以适应一个全新的快速发展的学术环境。     

草酸钙的形成机理及影响因素

目的 :探讨草酸钙结石的形成机理和影响因素。方法 :根据微溶电解质动力学原理 ,利用草酸与氯化钙作用形成草酸钙的性质 ,加入其它尿液中常见组分 ,测定草酸钙诱导期与过饱和溶液浓度的关系 ,并分析结石的显微结构。结果 :草酸钙的诱导期与溶液过饱和浓度呈反比关系 ,且不同干扰因素对草酸钙的过饱和比影响也不同。结论 :钙和草酸是草酸钙形成的必要条件 ;溶液的过饱和是草酸钙成核的基础 ;基质对草酸钙起胶结作用 ;氯化钠、氯化铵、氯化镁能促进草酸钙的形成 ,而氯化铁、尿素、甘氨酸能抑制草酸钙的沉淀。     

气固法合成氯磺化聚乙烯——Ⅱ.氯磺化反应影响因素

以氯化聚乙烯为原料,氯气和二氧化硫为反应气体,紫外光引发,气固法合成了氯磺化聚乙烯。通过元素分析得出,氯磺化反应中不存在氯化和脱氯的副反应。在釜式反应器内研究了氯磺化反应的气固相反应机理,发现气体的内扩散和本征化学反应是氯磺化反应的控制步骤,升高温度（在30－50℃范围内）使氯磺化反应后期的速率显著提高,这是由氯化聚乙烯的共结晶的熔融引起的。还讨论了氯化聚乙烯的链结构和固态结构对氯磺化反应的影响。     

NO在负载型金属氧化物催化剂上的氧化反应机理

研究了γ- Al2 O3负载的金属氧化物催化剂对 NO催化氧化性能。实验发现 ,30 0°C下催化剂活性顺序为 Mn>Cr>Co>Cu>Fe>Ni>Zn,P-型金属氧化物对 NO的氧化活性较强。对 Mn O2这种具有代表性的 P-型金属氧化物催化剂 ,提出了其 NO催化氧化的反应机理和动力学模型。     

气固法合成氯磺化聚乙烯——Ⅰ.气—固相反应机理

以氯化聚乙烯为原料,氯气和二氧化硫为反应气体,紫外光引发,气固法合成了氯磺化聚乙烯。通过元素分析得出,氯磺化反应中不存在氯化和脱氯的副反应。在釜式反应器内研究了氯磺化反应的气固相反应机理,发现气体的内扩散和本征化学反应是氯磺化反应的控制步骤,升高温度（在30－50℃范围内）使氯磺化反应后期的速率显著提高,这是由氯化聚乙烯的共结晶的熔融引起的。还讨论了氯化聚乙烯的链结构和固态结构对氯磺化反应的影响。     

Revision Total Knee Arthroplasty in Young Patients: Higher Early Reoperation and Rerevision

BackgroundRevision total knee arthroplasty (rTKA) rates are increasing in younger patients. Few studies have assessed outcomes of initial aseptic rTKA performed for younger patients compared with traditional-aged patients.MethodsA detailed medical record review was performed to identify patient demographics, medical comorbidities, surgical rTKA indications, timing from index TKA to rTKA, subsequent reoperation rates, component rerevision rates, and salvage procedures for 147 young patients (158 knees) aged 55 years and younger and for a traditional older cohort of 276 patients (300 knees) between 60 and 75 years. Univariate analysis was performed to assess differences in these primary variables, and a log-rank test was used to estimate 5-year implant survival based on either reoperation or component revision and salvage procedures.ResultsYounger TKA patients were more likely to undergo initial aseptic rTKA within 2 years of their primary TKA (52.5% vs 29.0%, P < .001) and were more likely to undergo early reoperation (17.7% vs 9.7%, P = .02) or component rerevision (11.4% vs 6.0%, P < .05) after rTKA. Infection and extensor mechanism complications were more commonly noted in younger patients. Estimated 5-year survival was also lower for both reoperation (59.4% vs 65.7%, P = .02) and component rerevision or salvage (65.8% vs 80.1%, P = .02).ConclusionEarly reoperation and component re-rTKA were performed nearly twice as often in younger rTKA than traditional-aged TKA patients. Care should be given to reduce perioperative infection and extensor mechanism failures after rTKA in younger patients.     

An inverted ankle joint orientation at foot strike could incite ankle inversion sprain: Comparison between injury and non-injured cutting motions of a tennis player

Ankle sprain is very common in sports. Research on its prevention is as important as on its treatment as recommended in the 2016 consensus statement of the International Ankle Consortium. Successful prevention depends on the understanding of its mechanism, which has been presented with quantities in some recent case reports. Inciting event was suggested to be an inverted ankle joint at foot strike, however, is still lacking evidence from comparison with non-injury trials. This study investigated the ankle joint orientation at foot strike in successful non-injury cases and compared them with a previously analysed ankle sprain injury case. Two injury-free cutting motions with similar movement approach to a previously analysed ankle sprain injury performed by the same athlete were collected from an online search and were trimmed from 0.05 s before until 0.30 s after the foot strike. The video sequences were then processed by video editing software and then analysed by a model-based image-matching motion analysis technique. Ankle joint orientation at foot strike and the profiles were presented in inversion, plantarflexion and rotation planes, for both the previously analysed injury case and the two non-injury cases. The ankle joint orientation at foot strike was 0–1 degree inverted and 10–21° dorsiflexed in the two non-injury cases, compared to 14° inverted and 16° plantarflexed in the previously analysed injury case. From the case comparison, it can be observed that an inverted ankle joint orientation at foot strike in an inciting event of ankle inversion sprain.     

Simultaneous bilateral versus unilateral tibial tubercle fractures

PurposeTibial tubercle/tuberosity fractures are rare injuries in young patients accounting for less than one percent of physeal fractures. Bilateral simultaneous fractures are even rarer, with only a few case reports in literature. The purpose of our study was to describe the largest case series of bilateral simultaneous tibial tuberosity avulsion fractures and compare it with unilateral fractures. We also wanted to compare our bilateral fractures case series with all the cases reported in the last 65 years.MethodsIRB approved retrospective study involving patients under age 18 years with tibial tuberosity avulsion fractures. Bilateral simultaneous fractures were compared to a unilateral group including demographic data, mechanism of injury, clinical exam findings, complication rates, and outcomes including return to function. Statistical analysis was performed using Mann-Whitney and Fisher Exact tests to compare the different groups.Results138 patients (131 males, 7 females) from a tertiary children’s hospital between 2012 and 2019 with tibial tuberosity avulsion fractures were included. 11 bilateral simultaneous fractures (BL Group) were identified and compared to age matched cohort from the 127 unilateral fracture patients (UL group). There was no significant difference found in BMI, height, weight, age, sex, mechanism of injury, return to functional range of motion, and return to sports between the groups. 7/11 (63%) of the patients in the BL group who sustained simultaneous fractures had to be home bound and could not attend school for an average of 8.3 weeks. There was a higher rate of complications in the BL group (63.3%) compared to the UL group (21.1%), which was statistically significant. The most common complications in the bilateral group were hardware removal and wound dehiscence.ConclusionThis first case series comparing unilateral versus bilateral simultaneous tibial tuberosity avulsion fractures suggests that the final outcomes of the two groups are similar, however it shows a significantly higher complication rate and hardware removal rate in the BL group. This study is also the first to highlight the significant initial morbidity in the BL fracture group with issues with regards to early mobility and loss of school-days. Keeping in mind the profound initial impact the bilateral injury poses to the patient; surgeons can possibly plan for rigid fixation for early mobilization to better prepare bilateral fracture patients for the early post-operative recovery process.