桡骨远端解剖型记忆聚合器的记忆生物力学研究

目的 研究桡骨远端解剖型记忆聚合器(anatomic distal radius Ni-tinol memory connector，DRMC)的记忆生物力学特性，为临床治疗提供记忆生物力学基础。方法 20根湿桡骨尸体标本分别制作桡骨远端骨折模型，以DRMC及普通钢板(common plate，CP)固定，采用生物力学测试及电测方法进行测试。结果 DRMC环抱支产生的最大轴向环抱力为：12．82MPa,DRMC组与CP组相比，虽然屈服载荷相近，但是应变值明显小于CP组;CP组的屈服扭矩高于DRMC组(P＜0．05)，前者为(1．8&;#177;1．3)N&;#183;m后者为(1．4&;#177;1．1)N&;#183;m，两者之比为1：1．3，比较接近。结论 DRMC固定桡骨远端骨折的记忆生物力学特性是：轴向环抱持骨有利于稳定，纵向加压及记忆效应的存在，可显著降低应力遮挡率，有利于促进骨折的愈合。     

桡骨远端解剖型记忆聚合器治疗桡骨远端骨折三维有限元分析

目的:探讨桡骨远端解剖型记忆聚合器(anatomicdistalradiusNitinolmemoryconnector,DRMC)治疗桡骨远端骨折的记忆生物力学特性。方法:采用三维建模及有限元方法,分析计算DRMC固定桡骨远端骨折时在骨折断面及周围所产生的应力并构建记忆应力场。结果:桡骨远端DRMC持骨支产生轴向持骨力为14.66MPa,持骨支最大主应力值为40～70MPa,最小主应力值为3～7MPa,而加压支应力值相对较大,为20～40MPa。结论:DRMC在骨折线周围的应力分布合理,轴向持骨力有利于早期骨折稳定,加压支纵向加压及记忆效应的存在,可将被固定的废用段转化为生长段,促进骨折愈合。     

桡骨远端解剖型记忆聚合器治疗桡骨远端骨折三维有限元分析

目的：探讨桡骨远端解剖型记忆聚合器(anatomic distal radius Nitinol memory connector，DRMC)治疗桡骨远端骨折的记忆生物力学特性。方法：采用三维建模及有限元方法，分析计算DRMC固定桡骨远端骨折时在骨折断面及周围所产生的应力并构建记忆应力场。结果：桡骨远端DRMC持骨支产生轴向持骨力为14．66MPa，持骨支最大主应力值为40～70MPa，最小主应力值为3～7MPa，而加压支应力值相对较大，为20～40MPa。结论：DRMC在骨折线周围的应力分布合理，轴向持骨力有利于早期骨折稳定，加压支纵向加压及记忆效应的存在，可将被固定的废用段转化为生长段，促进骨折愈合。     

桡骨远端解剖型记忆聚合器三维模型构建及记忆生物力学意义

目的:介绍桡骨远端解剖型记忆聚合器(anatomicdistalradiusmemorycompressionconnector,DRMC)三维模型的构建并进行三维有限元计算及分析,探讨相关的记忆生物力学临床意义。方法:采用大型有限元分析软件ANSYS7.0,建立DRMC三维模型。结果:所构建DRMC三维模型,客观反映DRMC的真实形态及生物力学行为,同时与桡骨远端三维模型有较高的帖服。结论:DRMC三维有限元模型的构建,可以为DRMC治疗桡骨远端骨折的力学行为以及DRMC相关力学基础研究提供精确模型。     

桡骨远端解剖型记忆聚合器三维模型构建及记忆生物力学意义

目的：介绍桡骨远端解剖型记忆聚合器(anatomic distal radius memory compression connector，DRMC)三维模型的构建并进行三维有限元计算及分析，探讨相关的记忆生物力学临床意义。方法：采用大型有限元分析软件ANSYS 7．0，建立DRMC三维模型。结果：所构建DRMC三维模型，客观反映DRMC的真实形态及生物力学行为，同时与桡骨远端三维模型有较高的帖服。结论：DRMC三维有限元模型的构建，可以为DRMC治疗桡骨远端骨折的力学行为以及DRMC相关力学基础研究提供精确模型。     

桡骨远端解剖型镍钛记忆合金接骨器治疗桡骨远端骨折的生物力学特性

目的寻求桡骨远端解剖型镍钛记忆合金接骨器(anatomicinferiorextremityofradiusNi-tinolmemoryconnector,AIER-NTMC)治疗桡骨远端骨折的生物力学特性。方法采用虚功原理及莫尔方法,计算AIER-NTMC固定桡骨远端骨折时在骨折断面及周围所产生的应力并构建应力场。结果桡骨远端AIER-NTMC环抱支受力和环抱支端点处位移δ之间的关系:当接骨器产生8%的弹性变形时,由几何条件δ=4.17mm,P=24N,产生的压强为2.00～2.67MPa。结论AIER-NTMC在骨折线周围的应力分布合理,轴向持骨有利早期骨折端的固定,加压支纵向加压可明显降低骨折线吸收后的应力遮挡率。     

膨胀式椎弓根螺钉在骨质疏松椎体的生物力学研究

目的:测试并比较自行设计的膨胀式脊柱内固定系统椎弓根螺钉以及CD-和TSRH椎弓根螺钉置入人骨质疏松腰椎体标本的最大轴向拔出力及最大旋入力矩,评价膨胀式脊柱内固定系统螺钉脊柱固定的稳定性。方法:将20个骨质疏松腰椎椎体标本随机分为2组,每组10个椎体(20侧椎弓根),随机选择每组椎体的一侧椎弓根置入膨胀式脊柱内固定系统椎弓根螺钉,(直径6mm,长45mm),另一侧置入CD-和TSTH螺钉,行螺钉拔出试验,测试并记录螺钉的最大旋入力矩和最大轴向拔出力。结果:几种螺钉的最大旋入力矩分别为膨胀式脊柱内固定系统椎弓根螺钉(1.59±0.32)N·m、CD-(1.57±0.29)N·m和膨胀式脊柱内固定系统椎弓根螺钉(1.56±0.31)N·m、TSRH(1.63±0.30),最大轴向拔出力分别为膨胀式脊柱内固定系统椎弓根螺钉(1176.2±213.67)N·m、CD-(589.8±147.87)N·m和膨胀式脊柱内固定系统椎弓根螺钉(1162.6±223.97)N·m、TSRH(584.18±157.53)。膨胀式脊柱内固定系统螺钉最大轴向拔出力最大,且与CD-和TSRH螺钉相比差异有非常显著性意义(P<0.001)。结论:膨胀式脊柱内固定系统螺钉对人骨质疏松椎体具有较强的椎弓根锚固作用。     

天鹅加压接骨器影响骨折愈合记忆生物力学实验研究

目的观察天鹅记忆加压接骨器(SMC)对骨折愈合影响,进一步探讨其生物力学意义和记忆生物力学机制。方法25只家犬两侧股骨中段横型截骨,左侧以SMC内固定,右侧以加压接骨板固定,术后1,2,4,8,12周行X线摄片、三点折弯测试观察。结果SMC组内固定后骨折愈合时间明显早于对照组,且愈合过程中未见明显的外骨痂及骨质疏松。骨折后4,8,12周,SMC组截骨处骨皮质厚度和股骨力学强度均高于对照组。SMC组4,8,12周内固定骨折愈合过程中生物力学测试结果分别为(48±13),(79±15),(86±18),与钢板组比较具有差异显著性的意义(P<0.05,t=7.56,P<0.01,t=4.33)。结论SMC内固定可起到有效内固定和持续加压作用,使骨愈合时间缩短,提高了固定段骨的力学强度。     

桡骨远端解剖型镍钛记忆合金接骨器治疗桡骨远端骨折的生物力学特性

目的：寻求桡骨远端解剖型镍钛记忆合金接骨器（anatomic inferior extremity of radius Ni-tinol memory connector, AIER-NTMC)治疗桡骨远端骨折的生物力学特性。方法：采用虚功原理及莫尔方法，计算AIER－NTMC固定桡骨远端骨折时在骨折断面及周围所产生的应力并构建应力场，结果：桡骨远端AIER－NTMC环抱支受力环抱支端点处理位称δ之间的关系。当接骨器产生8％的弹性变形时，由几何条件δ＝4.17mm，P＝24N，产生的压强为2．00－2．67MPa，结论LAIER－NTMC在骨折线周围的应力分布合理，轴向持骨有利早期骨期骨折端的固定，加压支纵向加压可明显降低骨折线吸收后的应力遮挡等。     

胫骨交锁髓内钉远端锁钉最佳效果的生物力学特性

目的:对胫骨交髓内钉远端不同锁钉方式进行生物力学测试,分析锁钉固定最佳效果的力学因素。方法:实验于2001-04/06在第一军医大学生物力学实验室完成,选择成人新鲜尸体胫骨标本6具(第一军医大学生物力学实验室提供),每具标本先后模拟骨折愈合、稳定骨折及不稳定骨折3种状态。4枚锁钉按胫骨自上向下位置分别编为1,2,3,4号。①骨折愈合组:安装交锁髓内钉模拟骨折愈合。②稳定骨折组:中段横行锯断模拟稳定性骨折,分为远端两枚锁钉;远端3号锁钉固定;远端4号锁钉固定。③不稳定骨折组:胫骨中段制成1.5mm骨缺损模拟不稳定性骨折,分为远端两枚锁钉;远端3号锁钉固定;远端4号锁钉固定。采用MTS试验机,轴向加载0-1000N,加载速度为50N/s,按制备顺序先后分别测量不同状态远端两枚锁钉处应力应变情况。结果:6具胫骨标本均进入结果分析。各组胫骨交锁髓内钉远端锁钉的应力应变:分别在4号钉2枚,3号钉2枚,4号钉1枚,3号钉1枚不同状态固定下,不稳定骨折组应力应变显著大于稳定骨折组[(6.47±0.49)×10-4比(4.57±0.46)×10-4mm/N,(8.10±0.64)×10-4比(4.97±0.05)×10-4mm/N,(9.18±0.65)×10-4比(5.82±0.76)×10-4mm/N,(11.10±1.04)×10-4比(6.67±0.40)×10-4mm/N,P<0.05];稳定骨折组应力应变大于骨折愈合组。②不同状态锁钉固定应力应变比较:4号钉2枚<3号钉2枚<4号钉1枚<3号钉1枚。结论:在远端两枚锁钉中,靠近侧的锁钉应力应变更大。远端改用一枚锁钉固定后,远端锁钉承受的应力应变进一步显著增加,且以离骨折线较近的一枚锁钉固定应力应变更大,易发生断裂及退钉,故应以两枚锁钉固定远端并远离骨折线。     

Determination of creatine kinase isoenzyme MB activity in serum using immunological inhibition of creatine kinase M subunit activity. Activity kinetics and diagnostic significance in myocardial infarction.

This is a new method for the determination of creatine kinase isoenzyme MB activity in serum. The method uses direct activity measurement of creatine kinase B subunit activity after blocking of CK-M subunit activity by inhibiting antibodies. The test takes no longer than 15 min. The method yields an intra-serial C.V. of 2.0-12.9%, and a C.V. from day to day of 5.5%. The detection limit is 3.4 U/l creatine kinase MB. In the 95 cases with proven myocardial infarction several types of creatine kinase MB activity kinetics could be determined. The percentage of creatine kinase MB of peak CK-total is 6-25%, with a mean of 11.1%. The amount of creatine kinase MB with respect to total CK activity after reinfarction is higher than the amount after initial infarction.     

Dissociable correlates of two classes of retrieval processing in prefrontal cortex

Although substantial evidence suggests that the prefrontal cortex (PFC) implements processes that are critical for accurate episodic memory judgments, the specific roles of different PFC subregions remain unclear. Here, we used event-related functional magnetic resonance imaging to distinguish between prefrontal activity related to operations that (1) influence processing of retrieval cues based on current task demands, or (2) are involved in monitoring the outputs of retrieval. Fourteen participants studied auditory words spoken by a male or female speaker and completed memory tests in which the stimuli were unstudied foil words and studied words spoken by either the same speaker at study, or the alternate speaker. On "general" test trials, participants were to determine whether each word was studied, regardless of the voice of the speaker, whereas on "specific" test trials, participants were to additionally distinguish between studied words that were spoken in the same voice or a different voice at study. Thus, on specific test trials, participants were explicitly required to attend to voice information in order to evaluate each test item. Anterior (right BA 10), dorsolateral prefrontal (right BA 46), and inferior frontal (bilateral BA 47/12) regions were more active during specific than during general trials. Activation in anterior and dorsolateral PFC was enhanced during specific test trials even in response to unstudied items, suggesting that activation in these regions was related to the differential processing of retrieval cues in the two tasks. In contrast, differences between specific and general test trials in inferior frontal regions (bilateral BA 47/12) were seen only for studied items, suggesting a role for these regions in post-retrieval monitoring processes. Results from this study are consistent with the idea that different PFC subregions implement distinct, but complementary processes that collectively support accurate episodic memory judgments.     

俯卧位通气对高海拔地区肺复张治疗无效急性呼吸窘迫综合征患者氧合的影响

目的 探讨俯卧位通气对高海拔地区肺复张术(RM)治疗无效急性呼吸窘迫综合征(ARDS)患者的治疗作用.方法 从海拔2260m的地区医院筛选RM治疗无效的41例ARDS患者[平均氧合指数( PaO2/FiO2)较RM前升高＜20％视为RM无效],依不同病因分为肺内源性ARDS组(ARDSp组)和肺外源性ARDS组(ARDSexp组),每组再按信封法随机分为俯卧位组和仰卧位组,即ARDSp俯卧位组(11例)、ARDSp仰卧位组(9例)、ARDSexp俯卧位组(10例)、ARDSexp仰卧位组(11例).在通气前及通气1、2、3、4h监测动脉血氧分压( PaO2)、PaO2/FiO2、静态顺应性(Cst)、气道阻力(Raw)的变化.结果 通气lh时,ARDSexp俯卧位组PaO2/FiO2( mm Hg,l mm Hg=0.133 kPa)即较通气前显著升高(157.4±40.6比129.3±48.7,P＜0.05),并随通气时间延长呈持续增高趋势,4h达峰值(219.1 ±41.1);且ARDSexp俯卧位组通气3h内PaO2/FiO2较其他3组显著增高,另3组间则差异无统计学意义.ARDSp俯卧位组、ARDSexp俯卧位组通气4h时PaO2/FiO2均较相应仰卧位组显著增高(208.8±39.7比127.4±47.1,219.1±41.1比124.9±50.8,均P＜0.05).4组通气前后Cst无显著改变,各组间差异也无统计学意义.ARDSp俯卧位组通气4h时Raw(cmH2O·L-1·s-1)较通气前显著降低(6.8±1.7比10.7±1.8,P＜0.05),且明显低于其他3组;其他3组各时间点Raw组内及组间比较差异均无统计学意义.结论 俯卧位通气作为ARDS机械通气重要策略之一,可以改善RM无效高原ARDS患者的氧合,为抢救患者赢得宝贵的时间.     

Digital imaging among medical facilities

The Department of Veterans Affairs (VA) in the USA operates a network of 172 medical centres which all utilize a hospital information system (HIS) which has been developed and is currently maintained by the VA. During the past several years, an image management and communication module has been developed, installed and clinically utilized at the Washington DC and Maryland VA Medical Centres. This image management and communication system, referred to as the decentralized hospital computer program (DHCP) imaging system, is fully integrated with a commercial picture archiving and communication system (PACS). The system is utilized to capture, archive, and display all images generated within the hospital including radiology, nuclear medicine, pathology, endoscopy, bronchoscopy, and dermatology, intraoperative photographs, ECG data, and a limited number of paper documents. The ultimate goal of the project is to have all patient text and image data available at any clinical workstation to any authorized user anywhere within the network of medical centres. Clinical requirements for an imaging workstation include ease of use, rapid and reliable access to the complete set of patient information, and images which are of acceptable quality to meet the requirements of the user and the subspecialty. Patient confidentiality and data security must be safeguarded at all times. Integration of the images with the remainder of the patient's database was found to be critical to the success of the project. The experience at the Washington and Maryland facilities suggests that an imaging system that is successfully integrated with a hospital information system can provide substantial clinical and economic benefits both within and among medical centres. Clinical acceptance and utilization of the system has been excellent, particularly in diagnostic radiology where DHCP Imaging has been interfaced to a commercial PAC system. Based upon this initial experience, the VA has begun to deploy the system throughout its large network of medical centres.     

Myocardial elastography at both high temporal and spatial resolution for the detection of infarcts

Myocardial elastography is a novel method for noninvasively assessing regional myocardial function, with the advantages of high spatial and temporal resolution and high signal-to-noise ratio (SNR). In this paper, in-vivo experiments were performed in anesthetized normal and infarcted mice (one day after left anterior descending coronary artery [LAD] ligation) using a high-resolution (30 MHz) ultrasound system (Vevo 770, VisualSonics Inc., Toronto, ON, Canada). Radiofrequency (RF) signals of the left ventricle (LV) in longitudinal (long-axis) view and the associated electrocardiogram (ECG) were simultaneously acquired. Using a retrospective ECG gating technique, 2-D full field-of-view RF frames were acquired at an extremely high frame rate (8 kHz) that resulted in high-quality incremental displacement and strain estimation of the myocardium. The incremental results were further accumulated to obtain the cumulative displacements and strains. Two-dimensional and M-mode displacement images and strain images (elastograms), as well as displacement and strain profiles as a function of time, were compared between normal and infarcted mice. Incremental results clearly depicted cardiac events including LV contraction, LV relaxation and isovolumetric phases in both normal and infarcted mice, and also evidently indicated reduced motion and deformation in the infarcted myocardium. The elastograms indicated that the infarcted regions underwent thinning during systole rather than thickening, as in the normal case. The cumulative elastograms were found to have higher elastographic SNR (SNR(e)) than the incremental elastograms (e.g., 10.6 vs. 4.7 in a normal myocardium, and 6.0 vs. 2.4 in an infarcted myocardium). Finally, preliminary statistical results from nine normal (m = 9) and seven infarcted (n = 7) mice indicated the capability of the cumulative strain in differentiating infracted from normal myocardia. In conclusion, myocardial elastography could provide regional strain information at simultaneously high temporal (>/=0.125 ms) and spatial ( approximately 55 microm) resolution as well as high precision ( approximately 0.05 microm displacement). This technique was thus capable of accurately characterizing normal myocardial function throughout an entire cardiac cycle, at the same high resolution, and detecting and localizing myocardial infarction in vivo.     

Clinical Pharmacokinetics of Morphine

Morphine, the most widely used mu-opioid analgesic for acute and chronic pain, is the standard against which new analgesics are measured. A thorough understanding of the pharmacokinetics of morphine is required in order to safely and effectively use this analgesic in a wide variety of patients with different levels of organ function. A MEDLINE search was conducted to identify literature published between 1966 and January 2002 relevant to the pharmacokinetics of morphine. These publications were reviewed and the literature summarized regarding unique and clinically important elements of morphine disposition relative to its parenteral administration (including intravenous, intramuscular, subcutaneous, epidural and intrathecal administration), absorption profile (immediate release, controlled release, and sublingual/buccal, and rectal administration), distribution, and its metabolism/ excretion. Special populations, including infants, elderly, and those with renal/liver failure, have a unique morphine pharmacokinetic profile that must be taken into account in order to maximize analgesic efficacy and reduce the risk of adverse events.