诊断超声介导微泡提高肝纤维化通透性及促进基因传递

目的 探讨诊断超声联合微泡对肝纤维化组织通透性的影响及其介导基因转染肝纤维化大鼠的有效性。方法 采用二甲基亚硝胺(DMN)法建立大鼠肝纤维化模型,80只大鼠在建模第4周末随机分为:模型对照组、单纯微泡组、单纯超声组和诊断超声联合微泡组。分别进行肝纤维化微血管通透性实验和基因转染实验,采用激光共聚焦显微镜观察伊文思蓝(EB)在肝纤维化组织内分布情况,同时定量检测肝纤维化组织内EB的含量,评估不同分组微血管通透性。荧光显微镜下观察含增强型绿色荧光蛋白报告基因的质粒转染大鼠肝纤维化模型的基因表达情况。结果 激光共聚焦显微镜显示诊断超声联合微泡组纤维化肝实质内可见明显的EB红色荧光。诊断超声联合微泡组纤维化肝组织中EB含量明显高于其他3组(P<0.05)。荧光显微镜下观察,相比其余3组,诊断超声联合微泡组增强型绿色荧光蛋白最多,基因转染效率最高。结论 诊断超声联合微泡在提高纤维化肝脏微血管通透性的同时可促进基因传递。     

Ultrasound imaging in an animal model of vascular inflammation following balloon injury

Cardiovascular disease is a major cause of morbidity and mortality in the world and better prevention and treatment strategies are needed. Studies from this laboratory have shown that perfluorocarbon exposed sonicated dextrose albumin (PESDA) microbubbles bind to inflamed vasculature through interactions with scavenger receptors (SR). This current study details the use of PESDA as a tool for accessing and quantifying the extent of vascular inflammation. Angioplastied rat aortas were evaluated with low mechanical index microbubble imaging techniques contrast pulse sequencing (CPS); Siemens Acuson Sequoia 15L8, 7–15 MHz ultrasound probe with a mechanical index of 0.09 to detect microbubble binding. Real-time polymerase chain reaction (RT-PCR) analysis of angioplastied aortas demonstrated a significantly (p < 0.01) increased expression of both SRs and Interleukin 6 (IL-6). Vessel wall enhancement was quantified using densitometry of CPS ultrasound images and correlated with the upregulated expression of scavenger receptors, Toll-like receptors and IL-6. This study demonstrates that PESDA, in conjunction with CPS ultrasound, is an effective imaging technique to better detect early vascular inflammation and potential cardiovascular disease.     

电镜硝酸镧示踪超声微泡造影剂开放血脑屏障

目的 研究超声波破坏微泡造影剂对大鼠血脑屏障通透性的影响。 方法 用电镜硝酸镧示踪法观察超声波破坏微泡造影剂对大鼠血脑屏障通透性的变化。 结果 超声波照射后即刻，即可见镧颗粒通过毛细血管内皮细胞及细胞间的紧密连接进入组织间隙，血脑屏障开放持续至6h，12h时已关闭。电镜下可以见到血管源性脑水肿，细胞器水肿不明显。 结论 超声波破坏微泡造影剂开放血脑屏障，为中枢神经系统疾病的治疗提供了一种无创、具靶向性的药物转运方法。     

超声介导下携尿激酶靶向微泡在兔动脉内溶栓后的电镜观察

目的 探讨携尿激酶靶向微泡溶解兔动脉内血栓后下的形态学改变。方法 在24只新西兰大白兔单侧股动脉制作富含血小板的混合性血栓,分成4组,每组6只:①单纯超声照射组(US);②单纯尿激酶静脉注射组(UK);③超声照射+微泡造影剂+尿激酶静脉注射组(US+ M+ UK);④超声照射+RGDS微泡造影剂+尿激酶组(US+ R+ UK)。将RGDS、微泡造影剂(SonoVue)和尿激酶通过直接联合法配制成携尿激酶的靶向微泡,超声照射30 min,多普勒血流仪监测血流量变化评价溶栓效果,然后对其行HE染色、电镜检查。结果 US+ R+ UK组血流量完全恢复,实现完全再通（P＜0.001）,HE染色显示血栓完全溶解,扫描电镜检查示血栓的纤维网状结构破坏,透射电镜显示血栓的大量降解碎片。结论血栓纤维蛋白网状结构的破坏、纤维蛋白的溶解是携尿激酶靶向微泡在兔动脉内溶解血栓的主要电镜表现。     

低频超声破坏微泡造影剂开放血脑屏障的实验研究

目的探讨不同强度的低频超声经颅诱导微泡造影剂破坏对大鼠血脑屏障的影响。 方法股静脉注入微泡造影剂后，采用频率43kHz，声强分别为1．2．1．5．1．8．2．3w／cm。的连续超声波经大鼠颅骨照射3min，荧光显微镜观察伊文思兰的渗出。 结果注射微泡造影剂后，声强1．2w／cm^2时超声波即可以开放血脑屏障，随声强的增加脑组织损伤加重。 结论低频超声诱导微泡造影剂破坏可以靶向开放血脑屏障。     

两种微泡造影剂开放大鼠血脑屏障的比较性研究

目的 探讨自制磷脂微泡和声诺维两种微泡对大鼠血脑屏障的影响.方法 将32只SD大鼠随机分为自制微泡即刻组、自制微泡24 h组、声诺维即刻组和声诺维24 h组,各组由尾静脉注射相应微泡后,在探头频率为1 MHz、声强4 W/cm2、辐照时间1.0 min参数下超声照射大鼠脑部,大体观察脑组织的蓝染程度及范围;伊文思蓝测定法观察大鼠血脑屏障通透性;光镜下观察脑组织、脑细胞和血脑屏障病理学改变.结果 声诺维24 h组大鼠脑组织蓝染程度及范围明显小于其他各组,脑组织通透性明显低于其他各组（P﹤0.05）,HE染色各组未见大鼠脑组织损伤及血细胞渗出.结论 自制磷脂微泡开放大鼠血脑屏障效果与声诺维相比无明显差异,且自制微泡开放血脑屏障的效果更为稳定.     

Insonation of the eye in the presence of microbubbles: preliminary study of the duration and degree of vascular bioeffects--work in progress.

OBJECTIVE: The purpose of this study was to investigate the presence and duration of vascular permeability changes induced by the combination of ultrasound and an intravascular microbubble contrast agent in the rabbit eye. METHODS: Five eyes were studied in 8 anaesthetized rabbits. Insonation was performed with a diagnostic B-mode system (center frequency = 2 MHz; mechanical index [MI] = 0.2 and 1.7) for 5 minutes after administration of perflutren microbubbles (0.07 mL/kg). Fluorescein fundus angiography was performed before and 3 minutes after insonation; at 6 minutes, color fundus photography was used to assess the dye leakage, bleeding, and alteration of the diameter of fundus vessels. RESULTS: Alteration of fundus vessel diameters was observed in 1 of 5 cases at a low MI and in 4 of 5 cases at a higher MI. In 1 case, leakage of fluorescein indicated increased permeability at the higher MI. No bleeding was detected in any case. CONCLUSIONS: The permeability change induced by insonation and this dose of an ultrasound contrast agent appears to be transient under the conditions studied, although the time delay between insonation and optical assessment limits the completeness of the findings. This preliminary study may be relevant to drug delivery strategies using ultrasound and microbubbles.     

Microbubble Type and Distribution Dependence of Focused Ultrasound-Induced Blood–Brain Barrier Opening

Focused ultrasound, in the presence of microbubbles, has been used non-invasively to induce reversible blood–brain barrier (BBB) opening in both rodents and non-human primates. This study was aimed at identifying the dependence of BBB opening properties on polydisperse microbubble (all clinically approved microbubbles are polydisperse) type and distribution by using a clinically approved ultrasound contrast agent (Definity microbubbles) and in-house prepared polydisperse (IHP) microbubbles in mice. A total of 18 C57 BL/6 mice (n = 3) were used in this study, and each mouse was injected with either Definity or IHP microbubbles via the tail vein. The concentration and size distribution of activated Definity and IHP microbubbles were measured, and the microbubbles were diluted to 6 × 10⁸/mL before injection. Immediately after microbubble administration, mice were subjected to focused ultrasound with the following parameters: frequency = 1.5 MHz, pulse repetition frequency = 10 Hz, 1000 cycles, in situ peak rarefactional acoustic pressures = 0.3, 0.45 and 0.6 MPa for a sonication duration of 60 s. Contrast-enhanced magnetic resonance imaging was used to confirm BBB opening and allowed for image-based analysis. Permeability of the treated region and volume of BBB opening did not significantly differ between the two types of microbubbles (p > 0.05) at peak rarefractional acoustic pressures of 0.45 and 0.6 MPa, whereas IHP microbubbles had significantly higher permeability and opening volume (p < 0.05) at the relatively lower pressure of 0.3 MPa. The results from this study indicate that microbubble type and distribution could have significant effects on focused ultrasound-induced BBB opening at lower pressures, but less important effects at higher pressures, possibly because of the stable cavitation that governs the former. This difference may have become less significant at higher pressures, where inertial cavitation typically occurs.     

Incidence of cardiac arrhythmias with therapeutic versus diagnostic ultrasound and intravenous microbubbles.

OBJECTIVE: The purpose of this study was to determine the type of arrhythmias induced with therapeutic versus diagnostic transthoracic low-frequency ultrasound (TLFUS) transducers in the presence of intravenous microbubbles. METHODS: Intravenous perfluorocarbon-exposed sonicated dextrose albumin (PESDA) microbubbles were infused or given as a bolus injection while TLFUS was applied in the standard parasternal and apical views with either a 1-MHz therapeutic ultrasound transducer or high-mechanical-index diagnostic ultrasound (1.7 MHz). RESULTS: Significantly more ectopy was produced by the therapeutic transducer, especially at higher-intensity settings in the continuous wave mode after bolus injections of PESDA (P < .001 compared with lower intensities and lower continuous infusion rates). Six patients (15%) had either clinical supraventricular tachycardia or nonsustained ventricular tachycardia after intravenous PESDA with therapeutic TLFUS. In comparison, diagnostic high-mechanical-index ultrasound produced only isolated ventricular ectopy and no sustained ventricular arrhythmias. CONCLUSIONS: Intravenously injected microbubbles and low-frequency therapeutic transducers operating at longer duty cycles and wide beam widths have the capability of eliciting clinically important arrhythmias in patients at high risk for such events.     

微泡声学造影剂气体构成对二次谐波显像的作用

目的探讨二次谐波成像条件下改变微泡造影剂的气体构成是否能够增强经静脉注射后的心肌显像效果。方法对１０条开胸犬经静脉注射含有不同气体的声振右旋糖酐白蛋白微泡造影剂ＲＡ（空气,ｒｏｏｍａｉｒ）、ＳＦ６（六氟化硫,ｓｕｌｆｕｒｈｅｘａｆｌｕｏｒｉｄｅ）、ＦＸ系列（含有氟碳气体Ｃ３Ｆ８、Ｃ４Ｆ１０、Ｃ５Ｆ１２）。二次谐波显像条件下取左心室短轴切面观,观察心肌造影效果。结果含有氟碳气体的微泡造影剂经静脉注射后二次谐波显像下产生强烈的心肌显影,心肌声学密度分别为（１４．７２±２．７）ｄＢ（ＦＸ３３０）、（１４．３±２．４ｄＢ）（ＦＸ４３０）、（１３．７８±２．２４）ｄＢ（ＦＸ５３０）;氟硫气体仅存在轻微的心肌显像［（６．２４±１．５８）ｄＢ］,但心腔显影强烈［（２９．４８±６．０２）ｄＢ］,空气造影剂经静脉注射后几乎不产生心肌显影［（２．５３±０．７８）ｄＢ］,心腔内造影剂亦较弱［（１１．３±４．９６）ｄＢ］。结论不同气体构成的微泡声学造影剂二次谐波显像效果差异显著。氟碳气体声振右旋糖酐白蛋白是较好的经静脉声学造影剂。     

Optimization of the size distribution and myocardial contrast effect of perfluorocarbon-filled albumin microbubbles by lyophilization under continuous negative pressure.

This study was undertaken to evaluate the effect of lyophilization under continuous negative pressure on perfluoropropane-filled albumin microbubble size distribution and myocardial contrast effect. Three different microbubble preparations were studied: (1) 1% albumin solution without a sugar (Optison), (2) 1% albumin and 5% dextrose (PESDA), and (3) 1% albumin and 5% fructose (PESFA). The 2 preparations containing sugar were also subjected to lyophilization under continuous negative pressure. Microbubble size distribution was measured with a Coulter Multisizer II (Beckman Coulter, Inc, Fullerton, Calif). The microbubbles were injected intravenously into a rat during intravital microscopy of the mesenteric microcirculation. Finally, the different albumin microbubbles were injected intravenously into 10 dogs, and myocardial contrast effect was assessed by videodensitometry. Results of the Coulter counter studies showed lyophilized PESFA to have a smaller size distribution with 99.9% + or - 0.1% of microbubbles <10 microm in diameter and 88.5% + or - 1.4% <4 microm in diameter (P <.05 compared with Optison or PESDA). On intravital microscopy, PESFA microbubbles behaved as intravascular tracers without microvascular plugging or coalescence. Finally, myocardial peak gray scale and area under the curve were significantly higher for PESFA than for PESDA or Optison, respectively. In conclusion, lyophilization of perfluoropropane-filled albumin microbubbles results in smaller microbubbles with a more uniform size distribution and brighter myocardial contrast. In addition, the substitution of fructose for dextrose improves size distribution and contrast effect. These findings have important implications regarding the use of novel imaging technologies that take advantage of microbubble destruction to image myocardial perfusion.     

Dynamic Visualization of Lymphatic Channels and Sentinel Lymph Nodes Using Intradermal Microbubbles and Contrast‐Enhanced Ultrasound in a Swine Model and Patients With Breast Cancer

Objective. Sentinel lymph node (SLN) identification using intradermal micro‐bubbles and contrast‐enhanced ultrasound (CEUS) has been recently reported in swine models and patients with breast cancer. The objective of this study was to investigate the dynamics of intradermally administered microbubbles as they travel to draining SLNs in pigs. We also performed a detailed study of the passage of microbubbles through breast lymphatic channels in a small group of patients with breast cancer. Methods. Nine anesthetized healthy pigs were used for the study, and 5 female patients with primary breast cancer were recruited. Pigs received intradermal injections of a microbubble contrast agent in several territories to access lymphatic drainage to regional lymph nodes. Patients had periareolar intradermal injection of the microbubble contrast agent. Ultrasound examination was performed in the real‐time contrast pulse sequencing mode with a commercial scanner. Results. Sentinel lymph nodes were identified rapidly (<1 minute) and consistently in pigs. Intradermal microbubble injection and CEUS were found to have perfect concordance with the Evans blue dye method in locating swine SLNs. In all 5 patients with breast cancer, the microbubble contrast agent entered breast lymphatic channels and traveled to draining ipsilateral axillary SLNs within 3 minutes. Conclusions. Intradermally injected microbubbles traverse readily though lymphatic channels in pigs and human breast tissue. The ability to rapidly identify SLNs in the diagnostic period would enable targeted biopsy and may facilitate preoperative axillary staging in patients with early breast cancer.     

Inhibition of carotid artery neointimal formation with intravenous microbubbles

Because therapeutic gene products such as synthetic antisense oligodeoxynucleotides (ODN) bind to albumin-coated microbubbles, we sought to determine whether IV perfluorocarbon-exposed sonicated dextrose albumin (PESDA) microbubbles could target their delivery to the carotid artery following balloon injury. In 5 pigs, the concentration of ODN taken up within the carotid vascular wall was found to be significantly increased when the IV antisense (ODN) was administered bound to PESDA (ODN-PESDA), and while transcutaneous low-frequency (20 kHz) ultrasound was applied over the carotid artery. Based on these results, a chronic model was then developed, in which 21 pigs received either IV ODN-PESDA, ODN alone, or control, following carotid balloon injury. At 30 days following balloon injury, percent area stenosis was only 8 +/- 2% in the ODN-PESDA groups compared to 19 +/- 8% and 28 +/- 3% in the other groups (p < 0.01). IV PESDA may be a method of noninvasively targeting the delivery of therapeutic genes.     

Myocardial Injury Induced by Ultrasound-Targeted Microbubble Destruction: Evidence for the Contribution of Myocardial Ischemia

Ultrasound-targeted microbubble destruction (UTMD) can cause left ventricular (LV) dysfunction and tissue alterations in rats when high ultrasound (US) energy and long duration of imaging are used. However, the mechanism underlying these alterations remains unclear. The aim of the present work was to investigate the possible role of ischemia in the pathogenesis of the UTMD-induced LV damages in rats. To address this issue, rat hearts were exposed in situ to perfluorocarbon-enhanced sonicated dextrose albumin (PESDA) and US at peak negative pressures of 0.6, 1.2 or 1.8 MPa for 1, 3, 9, 15 or 30 min. Blood pressure and electrocardiogram were continuously recorded during insonation. LV function was assessed before and immediately after US exposure, as well as at 24 h and 7 d. At each time point, groups of rats were euthanized and their hearts were harvested for morphologic analysis. Rats exposed to either PESDA alone or US alone showed no functional or morphologic abnormalities. By contrast, rats exposed to both PESDA and US exhibited transient LV dysfunction, transient ST-segment elevation, premature ventricular contractions, microvascular ruptures, contraction band necrosis and morphologic tissue damage. These bio-effects were spontaneously and completely reversible by one week, except in the groups exposed to the highest peak negative pressure for the longest duration, in which mild dysfunction persisted and interstitial fibrosis developed. In conclusion, simultaneous exposure of rat hearts to PESDA and US in vivo results in significant bio-effects that are similar to myocardial ischemia, including transient regional LV dysfunction, transient ST-segment elevation and myocyte contraction band necrosis. (E-mail: vanoverschelde@card.ucl.ac.be)     

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。     

Ultrasound targeted microbubble destruction increases capillary permeability in hepatomas

Ultrasound-targeted microbubble destruction (UTMD) has evolved as a promising tool for organ-specific gene and drug delivery. Taking advantage of high local concentrations of therapeutic substances and transiently increased capillary permeability, UTMD could be used for the treatment of ultrasound accessible tumors. The aim of this study was to evaluate if UTMD can locally increase capillary permeability in a hepatoma model of the rat. Furthermore, we evaluated whether UTMD can transfect DNA into such tumors. Subcutaneous Morris hepatomas were induced in both hind limbs of ACI rats by cell injection. A total of 18 rats were divided into three groups. Only one tumor per rat was treated by ultrasound. The first group received injection of Evans blue, followed by UTMD. The second group received a phosphate-buffered saline solution infusion and ultrasound to the target tumor after Evans blue injection. The third group received UTMD first, followed by Evans blue injection. Tumors and control organs were harvested, and Evans blue extravasation was quantified. Another 12 rats received DNA-loaded microbubbles by UTMD to one tumor, encoding for luciferase. Evans blue injection followed by UTMD showed about fivefold higher Evans blue amount in the target tumors compared with the control tumors. In contrast, no significant difference in Evans blue content was detected between target and control tumors when ultrasound was applied without microbubbles or when UTMD was performed before Evans blue injection. Plasmid transfection was not successful. In conclusion, ultrasound targeted microbubble destruction is able to transiently increase capillary permeability in hepatomas. Using naked DNA, this technique does not seem to be feasible for noninvasive transfection of hepatomas.     

低能量脉冲式超声联合微泡对兔VX2肿瘤微循环的阻断作用

目的探讨低能量脉冲式超声联合微泡对兔VX2肿瘤微循环的阻断作用及其病理机制。方法将36只皮下VX2荷瘤兔随机平均分成3组:超声微泡组注入0.2ml/kg体质量微泡5ml,并辅以超声辐照10min;单纯超声组注入生理盐水5ml,辐照10min;单纯微泡组仅注入0.2ml/kg体质量微泡5ml,不进行超声辐照。CEUS观察各组治疗前、治疗后0、30min、60min时血流灌注情况,比较各时间点的灌注面积。治疗后即刻随机选取各组6只荷瘤兔处死,完整切取肿瘤,行病理学检查。结果超声微泡组治疗后即刻肿瘤血流灌注完全消失,灌注面积为0,但30min及60min后灌注有所恢复,各时间点治疗后灌注面积显著大于治疗前(均P<0.05);大体病理检查见肿瘤微血管扩张、管壁结构崩解,弥漫性充血、出血和肿瘤组织水肿,局部血肿,形成血栓等。单纯超声组及单纯微泡组治疗前、后造影剂灌注面积无差异,肿瘤内部未见出血、水肿等。结论低能量超声联合微泡能够阻断肿瘤微循环,可能是由于空化效应导致血管壁损伤,组织水肿对局部肿瘤血液循环产生阻力,从而阻断肿瘤血液循环。     

Contrast Agent Kinetics in the Rabbit Brain During Exposure to Therapeutic Ultrasound

Ultrasound-stimulated microbubbles are currently under investigation as a means of transiently disrupting the blood-brain barrier (BBB) and it has been shown that the strength of this effect is highly dependent on ultrasound exposure conditions. The objective of this study was to investigate the potential for contrast agent destruction in the brain under conditions relevant to BBB disruption with a view to determining its possible influence on effective exposure parameters. An ultrasound imaging array was mounted within the aperture of a 1.68-MHz focused therapy transducer. Pulse lengths of 10 ms were used at repetition rates of 0.1–2.0 Hz and pressures from 0.30–0.88 MPa. Contrast imaging was performed after the bolus injection of Definity™, and contrast time-intensity curves were then analyzed for regions-of-interest exposed to the therapy beam. Individual therapy pulses resulted in microbubble destruction, with the degree of agent depletion and replenishment time increasing with transmit pressure. As the pulse repetition rate was increased, agent reperfusion between pulses was incomplete and the concentration within the beam was progressively diminished, to a degree dependent on both pressure and repetition rates. These results demonstrate that microbubble concentration can be substantially influenced by destruction induced by therapeutic ultrasound pulses. The kinetics of this effect may therefore be a significant factor influencing the efficiency of BBB disruption, suggesting that monitoring of the spatial and temporal distribution of contrast agents may be warranted to guide and optimize BBB disruption therapy in both preclinical and clinical contexts. (E-mail: goertz@sri.utoronto.ca)     

Spatial Distribution of Ultrasound Targeted Microbubble Destruction Increases Cardiac Transgene Expression But Not Capillary Permeability

Ultrasound targeted microbubble destruction (UTMD) has evolved as a promising tool for organ specific gene and drug delivery. Using DNA-loaded microbubbles, cardiac transfection has been shown to be feasible. However, two-dimensional properties of the ultrasound beam limit cardiac transgene expression to the focal zone, thus, reducing its potential therapeutic effect. The aim of this study was to test if spatial distribution of ultrasound targeted microbubble destruction in the heart could lead to augmented transgene expression or increased capillary permeability. Lipid microbubbles containing plasmids with a luciferase transgene were used to target rat hearts. The diagnostic ultrasound probe was fixed in a mid-short axis view with a gel stand-off between the chest and probe. Ultrasound (1.3 MHz) with a mechanical index of 1.6 was intermittently applied to rats during microbubble infusion. Rats were randomized to either stay in that position or move horizontally in a cranio-caudal direction (3 mm sweep) relative to the ultrasound probe during UTMD. After 4 days, organs were harvested and analyzed for reporter gene expression. Another group of rats received Evans Blue, followed by UTMD with unloaded microbubbles. Again, rats were randomized into a static or moving group. Hearts were harvested to evaluate extravasation of Evans Blue. Moving rats in a cranio-caudal direction significantly increased transgene expression by 19-fold in the anterior heart, by sixfold in the posterior heart and by 32-fold in the apex. Interestingly, Evans Blue extravasation was not augmented in the moving group. Spatial distribution of UTMD may increase transgene expression due to sonication of larger areas in the heart. In contrast, capillary permeability does not increase, indicating less capillary damage. (E-mail: raffi.bekeredjian@med.uni-heidelberg.de)     

尿激酶RGDS微泡在体溶栓的血流频谱特点与可能机制的实验研究

目的 用直接连接法制备的携尿激酶RGDS超声微泡溶解在体血栓,分析其血流频谱的特征性改变及可能的溶栓机制.方法 42只新西兰大白兔单侧股动脉制成富含血小板的混合性血栓模型,分成7组,每组6只:①单纯超声照射组(US);②超声照射+造影剂注射组(US+M);③单纯尿激酶静脉注射组(UK);④超声照射+微泡造影剂+尿激酶静脉注射组(US+M+UK);⑤超声照射+RGDS微泡造影剂组(US+R);⑥RGDS微泡造影剂+尿激酶静脉注射组(R+UK);⑦超声照射+RGDS微泡造影剂+尿激酶组(US+R+UK),进行在体溶栓治疗.将RGDS、微泡造影剂(SonoVue)和尿激酶通过直接联合法配制成6 ml的混悬液后经耳缘静脉注射,超声照射30 min,应用脉冲多普勒血流仪持续监测血流流速,对血流量和频谱变化特点进行分析.结果 120 min后US、UK、US+M、US+R及US+M+UK组血流量均未实现再通,R+UK组血流量实现部分再通,US+R+UK组血流量完全再通(P＜0.001).血流频谱特点为:未再通的各组在整个溶栓过程中血流频谱为持续小、低幅杂波;再通的R+UK组和US+R+UK组溶栓时血流频谱出现持续高幅、杂乱的波,US+R+UK组溶栓时超声波与血流频谱产生共振变化.结论 在体溶栓时通与不通的血流频谱各具特点,超声共振效应是促进溶栓的可能机制.