不同声学参数对血栓内微泡介导的超声辅助溶栓效果的影响

目的 探讨经导管向血栓内注射微泡和尿激酶后超声溶栓的体外实验中,不同声压和占空比对溶栓效果的影响。方法 制备稀释的超声微泡并组装体外实验设备。将90份新鲜人血血栓样本平均分为9组,包括8个实验组(实验1~8组)及1个对照组。向血栓内注射0.02 ml微泡稀释液及2万U尿激酶,并对各组进行不同的超声辐照;实验1~4组固定占空比为10%,声压分别为285 kPa、512 kPa、708 kPa和931 kPa;实验5~8组固定声压为931 kPa,占空比分别为1%、2%、5%和10%;对照组不予超声辐照。计算并比较各组溶栓率的差异,并通过超声观察血栓表现及微泡分布情况。结果 超声辐照后微泡在血栓内有均匀扩散并逐渐减少的趋势。固定占空比时,实验3、4组溶栓率明显高于对照组(P< 0.01),实验4组溶栓率高于实验1组(P< 0.05);固定声压时,实验6、7、8组溶栓率均明显高于对照组(P均< 0.01),实验8组溶栓率明显高于实验5组(P< 0.01)。其余各组间溶栓率差异均无统计学意义(P均> 0.05)。结论 向血栓内注射微泡和尿激酶有助于增强超声溶栓效果,超声辐照时以声压708 kPa、占空比> 2%为宜。     

靶向和非靶向微泡联合尿激酶超声溶栓的电镜表现

目的 比较靶向和非靶向微泡联合尿激酶超声溶栓的电镜表现。方法 将精氨酸-甘氨酸-天冬氨酸-丝氨酸片段（RGDS）与尿激酶（UK）以及超声微泡（SonoVue）通过机械振荡法,制备成靶向微泡。于30只新西兰大白兔单侧股动脉制备在体混合性血栓,并分为单纯超声辐照组（US组）、超声辐照+非靶向微泡造影剂+UK组（US+M+UK组）、超声辐照+靶向微泡造影剂+UK组（US+RGDS+UK组）。通过超声及多普勒血流仪观察溶栓效果,然后对股动脉离体标本行HE染色,并观察电镜表现。结果 溶栓20 min后,与US组和US+M+UK组比较,US+RGDS+UK组血流量明显恢复（P均<0.05）,US组与US+M+UK组比较差异无统计学意义（P均>0.05）。US+M+UK组HE染色显示管腔内充满血栓,血小板梁呈颗粒状、不致密,扫描电镜示粗大束状的胶原纤维上疏松附着少量细小纤维蛋白丝,大部分断裂;透射电镜示血栓大部分溶解为空泡状,可见白细胞或血小板降解的碎片。US+RGDS+UK组HE染色显示血栓完全溶解;扫描电镜示血栓的纤维网状结构被破坏,纤维蛋白完全的溶解;透射电镜示血栓降解为高电子密度的颗粒。结论 血栓结构的空泡化、纤维蛋白网架结构完全崩解和纤维蛋白的完全溶解是靶向微泡和UK联合溶栓的主要电镜改变。     

诊断超声联合微泡对肿瘤微循环的作用

目的 探讨高机械指数诊断超声联合微泡对大鼠Walker-256肿瘤微循环的作用。 方法 将29只皮下荷Walker-256肿瘤SD大鼠随机分为超声微泡组(n=15)、单纯超声组(n=7)和假照组(n=7):对超声微泡组采用声辐射力脉冲(ARFI)成像模式下诊断超声连续激励20次辐照肿瘤,同时经尾静脉推注微泡0.04 ml;对单纯超声组在行超声辐照的同时以等量生理盐水代替微泡;对假照组则采用假照方式,仅推注等量微泡溶液,但不发射超声能量。对所有动物于辐照前、辐照后即刻、10、20 min行CEUS检查。最后每组随机选取3只动物获取肿瘤组织标本,行病理学检查。 结果 辐照后即刻,超声微泡组辐照区几乎无造影剂充填,呈负性显影,肿瘤区平均造影峰值强度(PI)由25.17%减低到12.01%(P<0.01);单纯超声组及假照组辐照后即刻可见造影剂快速充填,灌注良好(P>0.05)。10 min后,超声微泡组造影可见血流逐渐恢复,但PI仍降低;20 min后肿瘤血流基本完全恢复,呈高灌注(P>0.05)。 结论 高机械指数诊断超声联合微泡能特异性地暂时降低大鼠Walker-256皮下移植瘤的微循环。     

超声微泡联合Ad-EGFP/HIF-1α介导EPCs归巢大鼠缺血心肌

目的 观察超声破坏微泡联合Ad-EGFP/HIF-1α介导EPCs移植归巢大鼠缺血心肌的可行性及有效性。方法 采用Percoll密度梯度离心法分离SD大鼠骨髓人脐血单个核细胞(MNCs),血管内皮生长因子(VEGF)、碱性成纤维细胞生长因子(bFGF)及表皮生长因子(EGF)诱导培养;Ad-EGFP/HIF-1α在HNK293细胞中进行扩增,之后感染体外培养的内皮祖细胞(EPCs)。将30只SD大鼠建立MI模型后随机分为5组:①空白对照组(C),②超声＋微泡组(US+MB),③单纯EPCs组(EPCs),④超声＋EPCs组(US+EPCs),⑤超声＋微泡+EPCs组(US+MB+EPCs)。EPCs移植后48 h处死大鼠,以激光共聚焦显微镜观察大鼠心肌组织内EPCs的分布,Western blot 检测HIF-1α的表达。结果 US+MB+EPCs组绿色荧光强度高于其他各组,Western blot显示,US+MB+EPCs组HIF-1α蛋白表达高于其他组(P<0.05)。结论 超声破坏微泡联合Ad-EGFP/HIF-1α介导EPCs移植可有效促进EPCs归巢,为干细胞移植治疗IHD提供了一种新的途径。     

制备RGDS/rt-PA双负载靶向微泡并初步评价其靶向性溶栓效果

目的 制备RGDS/rt-PA双负载靶向微泡,分析其对富血小板血栓（PRT）的靶向性和溶栓效果。方法 制备不同剂量梯度的RGDS及rt-PA单负载靶向微泡,以其最佳结合剂量、按照不同加入顺序（先加入RGDS,再加入rt-PA;先加入rt-PA,再加入RGDS;将RGDS及rt-PA混匀后加入）分别制备RGDS/rt-PA双负载靶向微泡,检测其结合率。比较裸微泡、单负载及双负载微泡的物理特性（直径、浓度及pH值）,不同剂量梯度的同一配体与微泡的单负载结合率,同一剂量梯度的不同配体与微泡的单负载结合率,加入顺序不同的配体与微泡的双负载结合率。制备体外PRT模型,检测RGDS/rt-PA双负载靶向微泡的声学显像特征、靶向溶栓能力。结果 不同微泡间的物理特性差异均无统计学意义（P均>0.05）。不同剂量梯度的rt-PA、RGDS与微泡单负载结合率的差异均有统计学意义,同一剂量梯度的rt-PA与微泡单负载的结合率均低于RGDS （P均<0.05）。加入顺序不同的配体与微泡的双负载结合率的差异有统计学意义（F=16.090,P=0.004）。将RGDS/rt-PA双负载靶向微泡注入血栓模型管腔后,超声可见均匀分布的点状高回声,血栓边界回声明显增强;扫描电镜下可见纤维蛋白网状结构明显破坏、纤维束断裂成细沙状,并可见变形融合的血细胞。结论 RGDS/rt-PA双负载靶向微泡性质稳定,与配体的结合率高,声学显像特征好,具备一定的PRT靶向性及溶栓能力。     

超声微泡介导血管内皮生长因子基因转染大鼠阴茎组织

目的 探讨超声靶向破坏微泡介导血管内皮生长因子165(VEGF₁₆₅)转染于高脂模型大鼠阴茎海绵体组织的可行性。方法 以含4％胆固醇及1％胆酸饲料饲养36只2月龄雄性SD大鼠3个月,建立大鼠高脂模型,将其随机均分为高脂模型组(对照组)、VEGF₁₆₅组和1.0 W/cm²超声+微泡+VEGF₁₆₅组(US+MB＋VEGF₁₆₅组)。于基因转染后7天处死大鼠,采用荧光定量PCR检测VEGF₁₆₅基因表达水平,以Western Blot检测大鼠阴茎组织VEGF蛋白质的表达水平,用免疫组织化学法(IHC)检测大鼠阴茎组织内皮型一氧化氮合成酶(eNOS)蛋白质表达。结果 转基因7天后,US+MB＋VEGF₁₆₅组VEGF₁₆₅基因水平明显高于VEGF₁₆₅组及对照组(P均<0.05),其阴茎海绵体组织VEGF蛋白质表达较VEGF₁₆₅组及对照组增加(P均<0.05);IHC结果显示,US+MB＋VEGF₁₆₅组大鼠阴茎组织eNOS较其他组高表达(P均<0.05)。结论 超声靶向破坏微泡可介导VEGF₁₆₅基因在大鼠高脂模型阴茎海绵体组织的高效转移,为基因治疗高脂勃起功能障碍提供了实验依据。     

环RGD多肽靶向微泡用于动脉血栓成像

目的 构建环RGD(Arg-Gly-Asp)多肽靶向微泡,评价其在高剪切应力下对体外和体内富血小板血栓的黏附效果。 方法 采用巯基-马来酰亚胺共价桥接法制备携环RGD多肽靶向微泡(Mb-cRGD)及同型对照微泡(Mb-CON),在平行板流动腔中测定二者靶向结合血小板的能力以及解离情况,在琼脂糖流动腔模型中观察二者对大鼠腹主动脉富血小板血栓的靶向显影效果。 结果 两种微泡粒径和浓度相近(P均>0.05);在3.60 dyn/cm²剪切应力下,Mb-cRGD与血小板糖蛋白(GP)Ⅱb/Ⅲa的结合数目明显多于Mb-CON(P<0.05);采用封闭抗体cRGDfV封闭GPⅡb/Ⅲa后,两种微泡均不能与之有效黏附,两者比较差异无统计学意义(P>0.05);Mb-cRGD与GPⅡb/Ⅲa半数解离和完全解离所需剪切应力明显高于Mb-CON(P均<0.05);对体外及体内的富血小板血栓行超声检查,可见Mb-cRGD较Mb-CON对血栓显影更清晰(P均<0.05)。 结论 环RGD多肽靶向微泡黏附富血小板血栓牢固而持久,可作为一种新的超声分子探针用于动脉血栓成像。     

自制纳米级E-选择素靶向超声微泡对缺血心肌分子成像

目的 采用自制的携E-选择素抗体的纳米级靶向超声造影剂对大鼠缺血再灌注损伤后的缺血心肌进行超声分子成像,评估其检测缺血心肌的可行性。方法 采用生物素-链亲和素方法制备纳米级靶向微泡,应用荧光显微镜及流式细胞仪检测微泡形态及抗体连接效率;将26只SD大鼠随机分为E-选择素靶向微泡组(MB_E组,n=10)、IGg抗体微泡组(MB_IGg组,n=10)、普通微泡组(MB_C组,n=6),制备心肌缺血再灌注损伤模型,将冠状动脉左前降支阻断15 min后恢复灌注,于再灌注后6 h经尾静脉分别注射3种微泡行CEUS。后行病理学检查。结果 MB_E组缺血区域声学强度(VI)显著高于非缺血区(P<0.05),也显著高于MB_C组、MB_IGg组缺血区域的VI(P<0.05);MB_C组、MB_IGg组缺血区域与非缺血区的VI差异无统计学意义(P>0.05)。结论 纳米级E-选择素靶向超声微泡可以早期检测到缺血心肌,有望实现缺血心肌的"记忆"成像。     

长脉冲超声联合脂质体微泡溶解微血栓的体外实验研究

目的评价长脉冲超声联合脂质体微泡造影剂溶解微血栓的疗效。方法构建评价溶栓效能的体外循环系统,通过造成200~300μm的微血栓阻塞于滤网来模仿体内的微循环栓塞。然后治疗组给予脂质体微泡加超声治疗15min,超声频率1MHz、声压1.5MPa、脉冲间隔3s,包括100、1 000、5 000 3种周期,对照组给予超声照射但无声学微泡。结果治疗组溶栓的效果随着脉冲的延长而增加,且对应的惯性空化效应强度也随之增加。1 000和5 000周期组的溶栓率显著高于单纯超声组(P均<0.01)。结论长脉冲超声联合脂质体微泡能实现良好的溶栓效果,且在一定范围内溶栓的效果随着脉冲的延长而增加。惯性空化可能是长脉冲超声介导微泡溶栓的重要机制之一。     

超声激励荧光微泡对兔乳腺癌转移淋巴结的释放作用

目的 观察超声激励荧光微泡空化对兔乳腺癌转移淋巴结的荧光释放作用。 方法 使用二甲基亚砜(DMSO)溶解绿色细胞膜荧光分子探针(DiO),抽取少量溶解液与脂质微泡混和,通过高速机械振荡制成荧光微泡。选取16只荷VX2乳腺癌的新西兰大白兔随机分成荧光微泡联合超声空化组和单纯荧光微泡组。荧光微泡联合超声空化组经瘤周皮下注射1 ml荧光微泡并按摩,待瘤周引流淋巴结超声显影后,采用脉冲式治疗超声间歇辐照淋巴结5次,共30 min;单纯荧光微泡组同样经瘤周皮下注射荧光微泡并按摩,但给予治疗超声假照。剖取淋巴结标本行冰冻组织切片,于激光共聚焦显微镜下观察淋巴结内的荧光分布情况,并定量分析荧光面积、累积光密度(IOD)及平均光密度(AOD)。 结果 荧光微泡联合超声空化组淋巴结的荧光面积、IOD和AOD均高于单纯荧光微泡组(P均<0.05)。 结论 荧光脂质微泡经瘤周注射不仅可进入兔乳腺癌模型的淋巴管使淋巴结显影,且可在治疗超声的激励作用下实现荧光物质在局部淋巴结高浓度释放。     

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.