Elution kinetics,antimicrobial activity,and mechanical properties of 11 different antibiotic loaded acrylic bone cement

Antibiotic-loaded acrylic bone cements (ALABC) spacers are routinely used in the treatment of prosthetic joint infections. The objectives of our study were to evaluate different ALABC for elution kinetics, thermal stability, and mechanical properties. A 10 or 20% mixture (w/w) beads of medium viscosity bone cement (DePuy, Inc) and vancomycin (VAN), gentamycin (GM), daptomycin (DAP), moxifloxacin (MOX), rifampicin (RIF), cefotaxime (CTX), cefepime (FEP), amoxicillin clavulanate (AmC), ampicillin (AMP), meropenem (MER), and ertapenem (ERT) were formed and placed into wells filled with phosphate-buffered saline. Antibiotic concentrations were determined using high-performance liquid chromatography. Antimicrobial activity was tested against Micrococcus luteus ATCC 9341 or Escherichia coli ATCC 25922. AmC, AMP, and FEP concentration rapidly decreased after day 2, being almost undetectable at day 4. Sustained and high elution rates were observed with VAN, GM, MOX, and RIF for the 30-day duration of the experiment. DAP, MER, ERT, and CTX elution rates constantly decreased from day 4. All antibiotics tested retained antimicrobial activity proving thermal stability. Mechanical properties of ALABC were maintained except when RIF was used.     

长臂单轴椎弓根螺钉在单纯性胸腰椎压缩性骨折复位固定中的应用及对肌肉损伤的影响

目的分析长臂单轴椎弓根螺钉经 Wiltse入路在单纯性胸腰椎压缩性骨折中的应用效果及对肌肉损伤的影响。方法选取自 2018年 1月至 2020年 8月周口市中心医院收治的单纯性胸腰椎压缩性骨折病人 87例，根据复位固定术式不同，分为观察组 38例、对照组 49例，其中观察组采取长臂单轴椎弓根螺钉经 Wiltse入路，对照组采取 AF系统经传统后正中入路。记录两组病人围术期指标、手术前后血清肌肉损伤指标［肌酸激酶( CK)、肌红蛋白( Mb)］变化；采用疼痛视觉模拟评分( VAS)评价病人不同时间节点疼痛水平；经胸腰椎正侧位片检查获取伤椎原始高度( H0)、术前及术后 1周伤椎椎体前缘高度( H1H2)，计算术前、术后 1周伤椎相对高度( H1/H0、H2/H0)及伤椎复位率，并测量矢状位 Cobb角变化；随访 3个月，采用 Oswestry功能障、碍指数( ODI)评价功能障碍情况，并统计手术相关并发症。结果观察组手术时长、术中失血量、术后引流量及首次下床活动时间均明显短于或低于对照组( P<0.05)。术后 3d，两组血清 CK、Mb水平均较术前升高( P<0.05)，且观察组血清 CK、Mb水平     

单纯胸外按压课程在高校人群心肺复苏培训中的应用

目的分析单纯胸外按压(chest compression cardiopulmonary resuscitation,CC-CPR)课程对高校人群胸外按压培训效果,探索心肺复苏公众培训新形式。方法招募120名高校人群随机分为CC-CPR课程组、Heart-saver CPR&AED First Aid(HS)课程组。两组分别进行不同课程培训,通过SUNLIFE Palm CPR胸腔按压反馈仪收集培训后按压数据,比较两组平均按压深度、平均按压频率、正确按压率、按压深度达标率、按压频率达标率、不良按压率。结果CC-CPR课程组在按压平均深度、频率上达到与HS课程组相同的培训效果,但在胸外按压达标率上比较,CC-CPR课程组比HS课程组在按压正确率、按压深度达标率、按压频率达标率上都有显著提升(P<0.05)。从不良胸外按压上比较,两组在滞留按压率、过深按压率、过慢按压率上都控制良好;但在过浅按压和过快按压发生率比较,CC-CPR课程组明显少于HS课程组,差异有统计学意义(P<0.05)。结论CC-CPR课程可使高校人群获得较HS课程更优的按压质量,且效率更高,是普及高校人群CPR培训方式的一种尝试与创新。     

A comparison between two powder compaction parameters of plasticity: The effective medium A parameter and the Heckel 1/K parameter

The purpose of the research was to introduce a procedure to derive a powder compression parameter (EM A) representing particle yield stress using an effective medium equation and to compare the EM A parameter with the Heckel compression parameter (1/K).     

Effects of nerve compression on fast axonal transport in streptozotocin-induced diabetes mellitus

Summary The hypothesis that nerves in diabetes mellitus exhibit an increased susceptibility to compression was experimentally tested. Inhibition of fast axonal transport was induced by local compression in sciatic nerves of rats with streptozotocin-induced diabetes mellitus. Fast anterograde axonal transport was measured after application of³H-leucine to the motor neurone cell bodies in the spinal cord. The sciatic nerve as subjected to local, graded compression in vivo by a small compression chamber. The amount of accumulation of proteins was quantified by calculation of a transport block ratio. Compression at 30 mm Hg for 3 h induced a significantly greater (p<0.05) accumulation of axonally transported proteins at the site of compression in nerves of diabetic animals (transport block ratio: 1.01±0.35; n=7) than in nerves of controls (0.67±0.16;n=7). Accumulation was significantly higher in ligature experiments of both control (1.34±0.44;n=8;p< 0.01) and diabetic animals (1.45±0.30;n=8 ;p< 0.05), indicating that the block of transport in compressed nerves was incomplete. Neither sham compressed diabetic (0.50±0.09;n=6) nor control (0.49±0.11;n=6) nerves showed any block of axonal transport. The possible causes of the increased inhibition of fast axonal transport in diabetic rats are discussed. The results indicate that diabetes may lead to an increased susceptibility of peripheral nerves to compression.     

Cathepsins B and L Increased during Response of Periodontal Ligament Cells to Mechanical Stress In Vitro

Cathepsin is a typical and well-characterized lysosomal cysteine protease that, under pathological conditions, is involved in tissue destruction. A recent immunocytochemical study demonstrated that cathepsins B (CAB) and L (CAL) were localized in the periodontal ligament (PDL) of the rat molar, and they were expressed in compressed sites during experimental tooth movement. Further, we demonstrated previously that the levels of CAB and CAL in gingival crevicular fluid increased during orthodontic tooth movement. Therefore, CAB and CAL may play important roles in the process of collagen degradation during orthodontic tooth movement, and our in vitro study examined the secretion of CAB and CAL in PDL cells following mechanical stress. PDL cells were subjected to 0.5, 1.0, 2.0, or 3.0 g/cm² of compression force or an increase in surface area by tension force of 0.28%, 0.95%, 1.72%, or 2.50% for 24 hr. For detection of CAB and CAL in conditioned medium, commercially available ELISA kits were used. We found compression and tension significantly increased the secretions of both CAB and CAL in PDL cells, which were exhibited in a time- and force magnitude-dependent manner. The compression-stimulated secretion of CAB was increased approximately 3-fold and that of CAL 4-fold, as compared with the control. Further, tension-stimulated secretion of CAB was increased by 1.5-fold and that of CAL 2-fold compared with the control. When analyzed using a semiquantitative polymerase chain reaction assay, CAB and CAL mRNA were increased in response to both compression and tension forces. These findings demonstrated that mechanical stress (compression and tension forces) causes an increase in secretion of CAB and CAL in PDL cells in vitro.