Treatment of thoracolumbar fracture with pedicle screws at injury level: a biomechanical study based on three-dimensional finite element analysis

The aim of this study was to investigate the biomechanical mechanisms of treatment of thoracolumbar compression fracture with pedicle screws at injury level based on a three-dimensional finite element method. We constructed one three-dimensional finite element model of T11-L1 in a patient with a compression fracture of the T12 vertebral body(anterior edges of vertebral body were compressed to 1/2, and kyphosis Cobb angle was 18.6°) fixed by four pedicle screws and another model fixed by six pedicle screws at the injured vertebrae, and then assigned different forces to the two models to account for axial compression, flexion, extension, left lateral bending, and rightward axial rotation by Ansys software. After different loading forces were applied to the models, we recorded stress measurements on the vertebral pedicle screws, as well as the maximum displacement of T11. The stress distribution suggested that stress concentration was appreciable at the root of the pedicle screws under different loading modalities. Under axial compression, flexion, extension, left lateral bending, and rightward axial rotation load, the stress for the superior screw was significantly greater than the stress for the inferior screw (P < 0.05). The stress in the six pedicle screw fixation model was significantly decreased compared to the four screw interbody fusion model (P < 0.05), but the maximum displacement of T11 between two models under different loadings was not statistically different. The use of pedicle screws at injured vertebral bodies may optimize internal fixation load and reduce the incidence of broken screws.     

间充质干细胞来源胞外囊泡救治辐射损伤的研究进展

间充质干细胞来源胞外囊泡（MSC-EV）在保留间充质干细胞（MSC）生物学功能的同时,能够避免MSC内在缺陷;MSC-EV脂质双分子层结构能够避免其脂质、蛋白、DNA、RNA等内容物被酶类物质降解;此外,MSC-EV适合通过永生化MSC技术进行大规模制备。因此,与MSC相比,MSC-EV是一种新型高效、安全、便捷、可行的非细胞治疗方法,且在组织修复及免疫调节方面呈现出同等功效。本文仅就MSC-EV在辐射损伤救治方面的研究进展作一综述。     

EMIT法与HPLC法测定人全血环孢素谷浓度的比较

目的：比较酶放大免疫（EMIT）法和HPLC法测定人全血环孢素（Cs A）浓度的区别与相关性。方法：收集肾移植患者服药后的稳态谷浓度血样119份,分别用EMIT法和HPLC法进行测定,考察两种测定方法的区别和相关程度。结果：HPLC法和EMIT法检测的Cs A血浓度差异有统计学意义（P〈0.05）,EMIT法测定全血Cs A浓度的结果较HPLC法测定的结果平均高26.2 ng·ml^-1,95%CI为（14.6-37.7）ng·ml^-1,两种分析方法具有良好的相关性（r=0.997 4）。结论：HPLC法和EMIT法测定Cs A全血药物浓度结果差异具有统计学意义,在临床进行Cs A药物浓度监测中应予以关注并作相应调整。     

心率减速力测定预测室性心律失常患者心脏猝死的价值

目的对176例经Holter心电图监护所检出的室性心律失常患者行心率减速力(DC)检测,评价其对心脏猝死的临床预测价值。方法采用美国DMS公司的12导联同步描记Holter心电监护仪,对门诊及病房就诊的受检者进行24⁷2 h的Holter心电图监护,除常规心律失常及ST段监护指标外,同时检测窦性心率震荡(HRT)及心率变异(HRV)的心搏间RR间期标准差指标(SDNN)。将Holter心电监护直接记录出室性心动过速(VT)者列为观察组,共176例,男93例,女83例,年龄3972 h的Holter心电图监护,除常规心律失常及ST段监护指标外,同时检测窦性心率震荡(HRT)及心率变异(HRV)的心搏间RR间期标准差指标(SDNN)。将Holter心电监护直接记录出室性心动过速(VT)者列为观察组,共176例,男93例,女83例,年龄39⁹2岁,平均53岁;随机选取性别和年龄与观察组相仿的182例为对照组进行对比分析。结果以心率减速力<4.5 ms为异常和<2.5 ms为显著异常的标准,两组的心率减速力值异常率分别为50.6%(89/176)和4.4%(8/182),观察组明显高于对照组(χ2=96.6,P<0.05);两组的心率减速力显著异常率分别为33.0%(58/176)和0%(0/182),两组间差异显著(χ2=75.6,P<0.05);室性心动过速患者的心率减速力异常检出率明显高于HRT和HRV检测指标(χ2=106.4,P<0.05;χ2=58.6,P<0.05)。结论室性心动过速患者的心率减速力测定,有较高的异常检出率。     

Single- Versus Double-Unit Umbilical Cord Blood Transplantation for Hematologic Diseases: A Systematic Review

Controversial results exist regarding the clinical benefits of single- vs double-unit umbilical cord blood transplantation (UCBT) in patients with hematologic diseases. A systematic review was conducted to evaluate this issue. The PubMed, Embase, and Cochrane Library databases were searched up to May 2018. A total of 25 studies including 6571 recipients were identified. Although double-unit UCB contained higher doses of total nucleated cells and CD34⁺ cells, it offered no advantages over single-unit UCB in terms of hematologic recovery, including the rate and speed of neutrophil and platelet engraftment. Double-unit UCBT was associated with higher incidences of grades II-IV acute and extensive chronic graft-vs-host disease, accompanied by a lower relapse incidence, which may be attributed to a graft-vs-graft effect induced by double-unit UCB. However, transplant-related mortality, disease-free survival, and overall survival were comparable between single- and double-unit UCBT. Although double-unit UCBT confers no clinical advantages over single-unit UCBT, certain patients, such as those at high risk of relapse, might benefit from double-unit UCBT, a possibility that needs to be clarified in future randomized trials.     

Role of Platelet Transfusion in the Reversal of Anti-Platelet Therapy

Antiplatelet therapy is extensively used in the primary and secondary prophylaxis of arterial thrombotic disorders. Aspirin, the most commonly used antiplatelet agent, is a cyclooxygenase−1 inhibitor and considered a mild to moderate inhibitor of platelet function. Therefore, often a second antiplatelet agent is necessary in certain clinical conditions requiring greater inhibition of platelet function. An adenosine diphosphate (ADP) receptor, P2Y12, is an important target for this purpose; several agents inhibit this receptor providing potent antiplatelet effect. One of the side effects of these agents is bleeding, which in some patients may require reversal of antiplatelet effect. Similarly, patients undergoing emergent surgeries may benefit from reversal of antiplatelet effect to avoid excessive surgical bleeding. This article reviews current literature on this topic.     

静电纺丝聚己内酯纳米纤维支架支持小鼠诱导多能干细胞表达心肌细胞标志物

目的利用多能干细胞与仿生材料支架构建人工心肌,探讨仿生材料支架本身对多能干细胞心肌特异性分化的直接作用,为构建组织工程心肌提供理论支持。方法采用静电纺丝聚己内酯纳米纤维仿生支架,接种小鼠i PSCs(mi PSCs)细胞培养分化15 d,免疫荧光染色与Western blot法检测多能干细胞与心肌细胞特异性标志物。结果mi PSCs特异性表达多能干性标志物Oct4和Nanog,而且能够在聚己内酯纳米纤维支架上集落样增殖、分化;培养15 d后,mi PSCs在支架上分化出心肌特异性标志物c Tn T和MLC2a双重免疫荧光染色阳性的细胞;心肌细胞特异性结构蛋白c Tn T、α-MHC和MLC2的表达水平,支架组全面高于对照组。结论聚己内酯纳米纤维仿生支架支持mi PSCs生长与心肌细胞特异性分化。     

卡拉胶寡糖对放射损伤的防护作用

目的 探讨卡拉胶寡糖对受6．0Gy X射线照射小鼠的辐射防护作用。方法采用6MV X直线加速器一次全身照射BALB／c小鼠，3个卡拉胶寡糖组照射前连续14d和照射后继续给药7d。观察小鼠30d存活率、外周血白细胞总数、胸腺指数和脾脏指数、脾脏NK细胞活性和腹腔巨噬细胞吞噬功能。结果卡拉胶寡糖组小鼠30d存活率比照射对照组提高75％～90％；而且卡拉胶寡糖能加速小鼠外周血白细胞的恢复，明显提高胸腺指数和脾脏指数，激活脾脏NK细胞的杀伤活性，增强巨噬细胞吞噬功能。结论卡拉胶寡糖对受照射小鼠有明显的辐射防护作用。     

军队离退休人员恶性肿瘤与体质的关联性

目的了解军队离退休老年人群恶性肿瘤的患病情况;掌握该群体恶性肿瘤患者的中医体质分型及特点,为从体质着手防治肿瘤提供依据。方法采取横断面现场调查填写老年生活质量调查表和中医体质调查表。应用Epidata 3.0建立数据库后进行数据统计分析。结果与结论军队离退休老年人群中肿瘤患病率为9.1%;75～84岁年龄区间肿瘤患病率最高,明显高于其他年龄段(P<0.05)。军队离退休老年人群中恶性肿瘤构成前10位的患者共354人,占该人群肿瘤患者总数的86.1%。在恶性肿瘤人群中,位于前3位的体质分别为气虚质(31.8%)、痰湿质(21.7%)和瘀血质(23.4%)。军队离退休老年人群恶性肿瘤和非恶性肿瘤人群的体质构成分布不同。