Octyl-a-cyanoacrylate adhesive in the treatment of tibial transverse fracture in rabbits

Asfracturescausedbyhighenergybecomemoreseriousandtheoccurrencegraduallyincreases,fractures,especiallycomminutedfractures,posemoredifficultiesinthetreatment.Inmanaging comminutedfractures,inappropriatestabilizationof fragmentedbonesisthemaincauseofunsuccessful internalfixationanddelayedunionornonunionof bones.Atpresent,commonlyusedmaterialsinfixation arescrews,steelwire,etc,.Stabilizationofmultiple bonefragmentsisstillthekeyinrealpractice.Octyl a cyanoacrylateadhesivehasbetterbiomechanical stre…     

Study of forced degradation behavior of pramlintide acetate by HPLC and LC–MS

Pramlintide acetate (Symlin^®), a synthetic analogue of the human hormone amylin. It was approved in March 2005 as a subcutaneous injection for the adjunctive treatment of patients who have type 1 or 2 diabetes mellitus. The objective of current investigation was to study the degradation behavior of pramlintide acetate under different ICH recommended stress conditions by HPLC and LC–MS. Pramlintide acetate was subjected to stress conditions of hydrolysis (acidic or alkaline), oxidation, photolysis and thermal decomposition. Extensive degradation products were observed under the hydrolysis, oxidation or thermal stress conditions, while minimal degradation was found in the photolytic conditions. Successful separation of drug from the degradation products was achieved by the validated chromatography (RP-HPLC and SCX-HPLC) methods. Subsequent to isolation, the molecular weight of each component was determined by LC–MS. The LC–MS m/z values and fragmentation patterns of 4 impurities matched with the predicted degradation products of pramlintide acetate.     

急性肺栓塞患者BNP、CTnI、D-dimer水平改变及其临床意义

【目的】探讨检测急性肺栓塞患者的血浆脑钠肽（BNP）、肌钙蛋白I（cTnI）及D‐二聚体（D‐dimer）水平变化的临床意义。【方法】选择本院2009年1月至2013年12月收治的急性肺栓塞患者64例,根据患者病情分为大面积肺栓塞组（ n ＝27）和非大面积肺栓塞组（ n ＝37）,对两组患者血浆cTnI、BNP及D‐dimer水平进行测定,观察比较两组患者各指标水平的变化及右心功能和病死率。【结果】大面积肺栓塞组BN P、血浆cTnI水平明显高于非大面积肺栓塞组,两组比较差异有显著性（ P ＜0．05）;两组D‐dimer浓度比较差异无统计学意义（ P ＞0．05）;大面积肺栓塞组的右心功能不全者和病死率均高于非大面积肺栓塞组,两组比较差异有统计学意义（ P ＜0．05）。【结论】检测BNP、cTnI及D‐dimer水平对APE患者临床诊断、临床决策及预后判断具有重要的临床意义。     

羟基磷灰石晶须/纳米氧化锌复合抗菌人工骨体外极限降解实验

目的 将纳米氧化锌对羟基磷灰石晶须进行改性,制备合成一种抗菌植骨复合材料,研究其在极限环境中的降解和物质变化.方法 通过溶胶-凝胶法制备纳米氧化锌,将制备所得纳米氧化锌改性羟基磷灰石晶须,得到羟基磷灰石晶须/纳米氧化锌复合材料.依据IS0 10993-14标准,采用柠檬酸缓冲溶液浸泡测试失重率,并对材料表面的形态变化作扫描电镜观察和X射线衍射分析.结果 HAPw/n-ZnO、HAPw降解率分别为：25.44％、18.59％,浸泡后通过扫描电镜可以明显观察到断裂的羟基磷灰石晶须,其表面的纳米氧化锌颗粒大量减少.XRD分析羟基磷灰石的三强峰降低.结论 HAPw/n-ZnO属于低可溶性材料.     

RNAlater在保存甲状旁腺腺瘤中的研究和探索

目的 探讨不同保存方法对甲状旁腺组织保存的影响,为组织库规范化建设提供理论支持.方法 收集北京协和医院2010年8月至2011年11月的散发甲状旁腺腺瘤组织共22例标本,所有标本均经手术病理证实,其中11例标本用传统液氮法保存（A组）,另11例标本用RNAlater保存（B组）,分别提取组织总RNA,测定OD 260/OD 280值;进行RNA质量评价,琼脂凝胶电泳判断RNA完整性;分别利用Realtime-PCR技术检测内参基因β-actin的表达情况.结果 在RNA的提取纯度和浓度及RNA完整性方面对比2组标本结果差异无统计学意义（P＞0.05）;B组内参基因β-actin的表达量明显高于A组（P＜0.05）.结论 RNAlater在保存RNA和预防RNA降解方面和传统液氮法相比无明显差异,但RNAlater保存法对于长期保存组织标本方面优于传统液氮法.     

甲壳素短纤维对聚己内酯体内的降解作用

目的 对纯聚己内酯（PCL）和甲壳素短纤维增强PCL复合材料进行体内降解实验研究，观察其理化性能变化及组织反应情况，为临床应用提供有价值的实验依据。方法 将纯PCL和甲壳素短纤维增强PCL植入兔背部脊柱两侧肌肉内，于2、4、8、12、16、24周取材，分别测试两种材料的生物吸收率、弯曲强度和弯曲模量，并行组织学和透视电镜观察。结果 甲壳素短纤维增强PCL初始强度大于纯PCL，在体内植入过程中，生物吸收率大于纯PCL，力学性能先高后低，强度和模量值24周时与初始值相差不大。未见材料周围组织变性、坏死或肉芽肿异常增生现象。结论 PCL复合甲壳素纤维后，加快降解速度，提高力学性能，材料-组织界面炎性反应轻，是一种具有开发价值的新型胸壁缺损修补及骨科内固定材料。     

一种新型的通用神经网络模型

讨论了由Ｄｕｍｅｌｈａｒｔ等提出的通用ＰＤＰ模型的基本思想及其局限性以后，提出了一种新型的通用神经网络模型。该模型对于退化问题、神经路径的生成和消失的动态处理，以及用之组成的神经网络结构方面均有许多优越性。此外，它还有助于更合理地解释人脑的工作机制及思维模拟。     

Degradation of DL-PLA-methadone microspheres during in vitro release

The in vitro degradation of polylactic acid of different weight average molecular weight (M_w) in microspheres containing variable amounts of methadone base (between 17 and 47%) was studied using the degradation index (DI), polidispersivity (pd) and molecular weights distribution. Both pd and DI are independent of initial methadone content and increase with M_w polymer, showing values of DI around 6.6 for the high M_w and 2.9 for the lower M_w. The distribution functions in the number of the molecular weights during the degradation assays indicate the presence of different break mechanisms for high and low molecular weight chains. A semiempiric model is proposed to explain the evolution of M_n during degradation in function of the number of bonds available for their breaking and hydrolysis rate constant. The first parameter ranges between 2.35 and 6.65 in function of M_w; the hydrolysis rate constant is independent of M_w and equal to 0.020 h⁻¹ (SD = 0.011 h⁻¹).     

The localization and characterization of proteinases for the initial cleavage of porcine amelogenin

Summary In the outermost layer of porcine-developing enamel adjacent to the ameloblasts in the secretory stage, the activities of two proteinases having molecular masses of 76 and 78kDa were detected by enzymography using gelatin as a substrate. On the other hand, high activities of known 30 and 34kDa proteinases were localized in the inner layer of the enamel. The 76kDa proteinase cleaved the carboxylterminal peptide of porcine 25kDa amelogenin to convert it to 20kDa amelogenin. The 78kDa proteinase also acted on the 25kDa amelogenin similarly, but its activity was weak. The results indicate that the 25kDa amelogenin synthesized and secreted by ameloblasts is converted to 20kDa amelogenin by the action of proteinase localized in the outermost layer of the secretory enamel, and then further degraded by the proteinases in the inner layer of the enamel associated with the increase of mineralization.