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)     

Ultrasound-Targeted Microbubble Destruction Accelerates Angiogenesis and Ameliorates Left Ventricular Dysfunction after Myocardial Infarction in Mice

Failure of coronary recanalization within 12 h or no flow in the myocardium after percutaneous coronary intervention is associated with high mortality from myocardial infarction, and insufficient angiogenesis in the border zone results in the expansion of infarct area. In this study, we examined the effects of ultrasound-targeted microbubble destruction (UTMD) on angiogenesis and left ventricular dysfunction in a mouse model of myocardial infarction. Fifty-four mice with MI were treated with no UTMD, ultrasound (US) alone or UTMD four times (days 1, 3, 5 and 7), and another 18 mice underwent sham operation and therapy. Therapeutic US was generated with a linear transducer connected to a commercial diagnostic US system (VINNO70). UTMD was performed with the VINNO70 at a peak negative pressure of 0.8 MPa and lipid microbubbles. Transthoracic echocardiography was performed on the first and seventh days. The results indicated that UTMD decreased the infarct size ratio from 78.1 ± 5.3% (untreated) to 43.3 ± 6.4%, accelerated angiogenesis and ameliorated left ventricular dysfunction. The ejection fraction increased from 25.05 ± 8.52% (untreated) to 42.83 ± 9.44% (UTMD). Compared with that in other groups, expression of vascular endothelial growth factor and endothelial nitric oxide synthase and release of nitric oxide were significantly upregulated after UTMD treatment, indicating angiogenesis. Therefore, UTMD is a potential physical approach in the treatment of myocardial infarction.     

超声波介导微泡破裂促EGFP基因转染大鼠脑组织的实验研究

目的 探讨超声波介导微泡造影剂破裂促外源基因在中枢神经系统转染的可行性.方法 15只大鼠分3组,1组经股静脉输入含绿色荧光蛋白质粒(pEGFP)的造影剂0.8 ml,立即用超声波照射大鼠颅骨3 min;第2组输入相同的造影剂0.8 ml,不采用超声波照射;第3组输入不含造影剂的pEGFP 0.2 ml,立即超声波照射3 min.48 h后处死大鼠,荧光显微镜下观察绿色荧光蛋白表达.结果 只在股静脉输入含pEGFP的造影剂,并经超声波照射的大鼠微血管壁上观察到绿色荧光蛋白表达.结论 以微泡造影剂为基因载体,通过超声波靶向破坏微泡,有可能在脑血管内皮细胞中获得基因转染.     

负载阿霉素的洗脱微球肝动脉化疗栓塞治疗难以手术切除的肝细胞肝癌的疗效和安全性

肝细胞肝癌(hepatocellular carcinoma,HCC)手术治疗后仍有较高的复发率,这些复发的患者中有很大一部分失去了再次手术的机会.对此类失去手术指征的HCC患者,通常采用一些非手术治疗方法,如经导管肝动脉栓塞(transcatheter arterialembolization,TAE)、经导管肝动脉化疗栓塞(tran-scatheter arterial chemoembolization,TACE)或射频消融.其中TACE应用广泛,其疗效已被临床证实,是目前无法手术切除HCC患者的首选治疗手段.     

Efficacy of Enrofloxacin in a Mouse Model of Sepsis

We examined the efficacy of enrofloxacin administered by 2 different routes in a mouse model of sepsis. Male CD1 mice were infected with a bioluminescent strain of enteropathogenic Escherichia coli and treated with enrofloxacin either by injection or in drinking water. Peak serum levels were evaluated by using HPLC. Mice were monitored for signs of clinical disease, and infections were monitored by using bioluminescence imaging. Serum levels of enrofloxacin and the active metabolite ciprofloxacin were greater in the group treated by injection than in controls or the groups treated by administration in drinking water. Survival of the group treated with enrofloxacin injection was greater than that of controls and groups treated with enrofloxacin in the drinking water. Bioluminescence in the group treated with enrofloxacin injection was less than that in the groups treated with oral administration at 12 h and in the groups treated orally and the control group at 16 h. According to these findings, we recommend the use of injectable enrofloxacin at 5 mg/kg SC for mice with systemic infections.Abbreviation: MIC, minimal inhibitory concentrationSepsis is defined as the systemic inflammatory response to the presence of bacterial infection.⁶ It affects approximately 750,000 people annually in the United States, with a mortality rate of 30% to 50% and a financial burden of US$16.7 billion dollars.¹ Septic shock is persistent hypotention with hypoperfusion abnormalities or organ dysfunction secondary to sepsis and kills 10 times more people than myocardial infarction in the United States.^7,38 Bacterial isolates from patients with gram-negative infections most commonly include Escherichia coli, Klebsiella species, or Enterobacter species.⁶ Due to the widespread and severe nature of this disease, this is an active area of scientific research.^14,17Enrofloxacin is a frequently used antibiotic approved for use in dogs, cats, cattle, and pigs in the United States. It is a fluoroquinolone antibiotic that leads to bacterial cell death through the inhibition of topoisomerase II, which controls supercoiling of bacterial DNA.³³ The bactericidal effect is dependent on the concentration of antibiotic present in tissues,³⁵ both of the parent compound and of the active metabolite ciprofloxacin.¹⁶ Enrofloxacin has been studied in a wide range of laboratory animal species including bovines,^16,26,27 dogs,^5,36 frogs,^20,25 horses,⁴¹ macaques,⁴ marmosets,⁴⁴ mice,^{22,32,34,36,40,49} rabbits,¹⁹ rats,⁸ sheep,¹⁵ and swine.^15,37,52 Published doses in veterinary formularies range from 2.5 to 20 mg/kg for enteral and parenteral bolus dosing and for rodents at 0.05 to 0.2 mg/mL in drinking water.^11,45,46 In laboratory animal medicine, fluoroquinolone antibiotics are sometimes administered as a therapeutic agent to populations of animals. One example of this practice is for eradication of an opportunistic pathogen such as Pneumocysitis carinii in genetically modified mice.³² In addition, fluroquinolones are used on a large scale prophylactically in research protocols involving bone marrow transplantation in mice.³⁹ When large groups of animals require treatment, the route of administration can affect the personnel time required to conduct the research.Bioluminesence imaging is a noninvasive imaging modality that has been used to study cell trafficking, tumor development, gene expression, gene therapy, inflammation and infection, protein–protein interactions, and protein stability and function in laboratory rodents.¹³ Bioluminescent imaging systems use specialized charge-coupled cameras to capture low amounts of light. Organisms can be genetically engineered to express firefly luciferase or other types of luciferase enzymes, which emit light when the organisms are provided an exogenous substrate, such as luciferin, in the presence of ATP and oxygen.²⁹ In addition, specialized bacteria have been engineered to carry genes for both the luciferase and the substrate, a long-chain fatty aldehyde, and thus do not require an exogenous source of substrate.⁴⁷ These types of modified bacteria have been used to study the progression and treatment of bacterial infections of the gastrointestinal tract,^10,21 wounds,^23,47 and surgical implants.^30,51,53 Advantages of bioluminescence imaging include the ability to assess the spatial and temporal distribution of bacteria after intervention in the same animal, thus reducing animal numbers.The purpose of the current study was to refine a model of sepsis by evaluating the efficacy of different routes of administration of prophylactic antibiotics. This work was part of a larger study evaluating the pathogenesis of hospital-acquired infection in patients receiving blood transfusions during concurrent antibiotic therapy. With an effective model system, research results can be translated to treatment of human diseases. Serial noninvasive optical imaging of a bioluminescently engineered strain of enteropathogenic Escherichia coli was used as a biomarker of bacterial infection in the presence of mitigating drug regimens. We hypothesized that there would be no difference in the severity of infection, evaluated as photons per second emitted from a region of interest over the abdomen, between animals that received enrofloxacin via different routes of administration in this model of sepsis. Our goal was to establish an effective method of preventing or treating gram-negative sepsis through antibiotic administration that minimized animal handling and manipulation, promoted animal wellbeing, and maximized the information obtained from the animals used in our research.     

超声破坏微泡促进骨骼肌血管新生的实验研究

目的　探讨超声破坏微泡引起的微血管破裂促进大鼠骨骼肌血管新生的有效性。方法　将 30只 Wistatr大鼠随机分为 3组 ,1组经静脉输入自制的白蛋白微泡造影剂 0 .5 ml,同时用 1MHz,2 .0 W/cm2 的超声在其骨骼肌局部间歇作用 2 min;1组仅在骨骼肌局部用同等的超声能量作用 ;第 3组作为对照组。实验结束后 ,各组分别取 1只做石蜡切片观察显微结构的变化。各组剩余的大鼠于 2周后处死 ,免疫组化观察骨骼肌中血管内皮生长因子 (VEGF)和血管内皮细胞 因子的表达。结果　超声破坏微泡组大鼠骨骼肌中可见 VEGF和 因子的表达较多 ,有较多的新生血管生成 ;而单纯超声作用组 VEGF和 因子表达较少 ,血管新生不明显 ;对照组中无 VEGF和 因子表达 ,无新生血管。结论　超声破坏微泡引起的微血管破裂可刺激骨骼肌中内源性 VEGF的分泌 ,促进血管生成。     

Microbubble Injection Enhances Inhibition of Low-Intensity Pulsed Ultrasound on Debris-Induced Periprosthetic Osteolysis in Rabbit Model

We determined whether the addition of microbubbles enhances the effect of low-intensity pulsed ultrasound (LIPUS) on bone–implant integration in an early-stage osteolysis model. The bone canals were injected with titanium particles before implantation to establish the periprosthetic osteolysis model. Before ultrasonic therapy, the microbubble-enhanced LIPUS group (G_Ti-Us-Mb) received an intra-articular injection of microbubbles. Biomechanical testing revealed that G_Ti-Us-Mb had significantly greater fixation strength than the LIPUS group (G_Ti-Us). Distal periprosthetic bone mineral density was also higher in G_Ti-Us than in the Ti group (G_Ti), but no significant increase was detected after administration of microbubbles. Histomorphometric analyses revealed that bone formation around the implant in G_Ti-Us was enhanced by the addition of microbubbles in G_Ti-Us-Mb. Taken together, our data indicate that microbubble injection enhances the inhibitory effect of LIPUS on debris-induced osteolysis and further strengthens the mechanical fixation of implants in an early-stage osteolysis model in vivo.     

超声破坏微泡造影剂促进大鼠心肌血管新生的实验研究

目的探讨超声破坏微泡刺激大鼠心肌内源性VEGF分泌、促进血管生成的新途径。方法正常成年Wistar大鼠30只随机分为3组。第1组超声破坏微泡组，第2组单纯超声辐照组，第3组对照组。每组均进行3次处理。第一次处理3d后每组各取1只大鼠断颈处死后取其心肌，常规HE染色光镜观察心肌结构变化。剩余大鼠于2周后取材，免疫组化检测心肌组织中VEGF表达，CD34免疫组化检测评定超声破坏微泡促进心肌血管新生疗效。结果超声破坏微泡组心肌组织中见大量VEGF和CD34表达，新生血管较多。单纯超声组心肌组织中有较少VEGF和CD34表达，新生血管较少。对照组仅有极少量VEGF和CD34表达，未见明显新生血管。结论超声破坏微泡可刺激心肌内源性VEGF分泌，促进血管新生。     

Noninvasive Imaging for Assessment of the Efficacy of Therapeutic Agents for Hepatocellular Carcinoma

Morphological imaging techniques are typically used in the anti-cancer drug efficacy evaluation process. However, these techniques can evaluate the therapeutic efficacy only when the tumor shows anatomic changes—usually at later stages, when the therapeutic effects are poor. In contrast, molecular imaging allows noninvasive monitoring of tumor growth, assessment of drug metabolism, and evaluation of therapeutic efficacy at the molecular and cellular levels. Multimodality molecular imaging, which combines the advantages of various imaging modalities, provides even more comprehensive therapeutic efficacy assessment in preclinical and clinical studies. This review provides an overview of molecular imaging evaluation of therapeutic efficacy of the anti-tumor drugs in hepatocellular carcinoma (HCC) both in preclinical and clinical research, which holds great promise in guiding HCC treatment into the era of precision medicine.

     

多媒体集体宣教模式在肝癌切除手术患者中的应用

目的 探讨多媒体集体宣教模式在肝癌切除手术患者中的应用方法及效果.方法 便利抽样法选择2014年1月至2015年12月在第二军医大学东方肝胆外科医院行肝癌切除的患者200例,按照手术时间的先后将其分为对照组和观察组各100例,分别采用传统宣教模式和多媒体集体宣教模式,比较两组患者的术前访视所需时间、Zung氏焦虑自评量表(self-rating anxiety scale,SAS)评分和满意度情况.结果 观察组患者术前访视所需的时间短于对照组,SAS评分低于对照组,满意度高于对照组,差异均有统计学意义(均P＜0.05).结论 多媒体集体宣教模式的应用有利于提高访视效果、访视效率及患者满意度.     

Pulsed-Focused Ultrasound Enhances Boron Drug Accumulation in a Human Head and Neck Cancer Xenograft-Bearing Mouse Model

Purpose

This study aims to demonstrate that pulsed high-intensity focused ultrasound (pulsed-HIFU) may enhance the fructose-conjugated 4-borono-L-phenylalanine (BPA-Fr) accumulation in tumor lesion using ¹⁸F-FBPA-Fr microPET scans.

Procedures

To the mice bearing orthotopic SASC03 human tongue squamous carcinoma xenograft, a 2-min pulsed-HIFU was applied to tumor. Immediately after pulsed-HIFU treatment, ¹⁸F-FBPA-Fr was intravenously injected, and biological characterizations including microPET imaging and biodistribution were conducted.

Results

Both biodistribution studies and microPET imaging performed after intravenous injection of ¹⁸F-FBPA-Fr revealed higher tumor uptake in HIFU-treated mice than that of the control. CD31 and Ki-67 histochemical staining of tumor sections and H&E staining of nearby normal tissues revealed no significant difference between the pulsed-HIFU-treated mice and the control.

Conclusion

This study demonstrated that pulsed-HIFU was beneficial to the accumulation of boron drug in the head and neck tumor lesion and may enhance the therapeutic efficacy of clinical BNCT.