超声治疗动脉粥样硬化性心血管疾病研究进展

超声干预治疗动脉粥样硬化性心血管疾病（atherosclerotic cardiovascular disease,ASCVD）是一种非侵入性治疗方法，其应用于临床治疗的前景广阔。超声波在身体组织中产生的机械、空化及生化等一系列作用可以有效清除血管中的斑块或血栓。但是，安全性是超声疗法应用于临床中亟需解决的首要问题。超声波在身体组织中的传播会引起组织损伤。另外，安全处理因超声刺激而产生的斑块或血栓碎片也是超声疗法应用中面临的挑战。除了确保安全性，合理制定治疗方案及治疗参数从而提高超声疗法疗效是超声疗法应用于临床中有待解决的重要问题。本文结合近年来超声干预治疗动脉粥样硬化性心血管疾病方面的各种临床、动物及体外模型实验研究结果，综述了超声干预治疗的机制、不同治疗方法和治疗参数的效果、如何确保安全性，以及提高超声疗法疗效需解决的一系列问题，进而提出可能的解决方案。     

超声在植物生理学领域的应用

综述了超声在植物生理学研究和实践中的应用。研究涉及超声对植物体呼吸强度、萌发率、生根状况、某些代谢途径的影响以及超声的空化作用对植物体生理学方面的影响。在植物生理学领域中超声的应用主要是利用了超声的空化作用、机械作用和热效应。     

超声在生物技术中应用的研究进展

超声波应用于生物技术是一个比较新的研究领域.许多研究发现,在有酶或细胞参与的情况下,一些过程可在超声作用下被激活.一般来说,较低强度的超声波可以通过改进反应物的质量传输机制,提高酶及固定酶的催化活性或加速细胞的新陈代谢过程.文中举例讨论了近年来超声在生物技术中应用的研究进展及前景.     

超声空化效应和超声微泡在生物医学中的应用

近年来,随着超声技术在医疗领域的广泛应用及超声造影剂研制的进展,空化效应和超声造影剂协同运用作为一种高效、安全、操作简单,且具有一定靶向性的无创治疗手段,在基因治疗、药物输送、溶栓和治栓,以及炎症与肿瘤的靶向诊断与治疗方面显示了巨大的运用潜力。简要综述了超声空化效应和超声微泡的治疗机制及应用。     

超声靶向微泡破坏与载药/载基因纳米粒联合应用的生物物理学机制及应用研究进展

超声靶向微泡破坏(ultrasound-targeted microbubble destruction, UTMD)能够安全、高效、简便地递送药物与基因,是当前超声医学领域的研究热点,其机制主要涉及超声辐照微泡引起的空化效应及其二级效应、内吞作用与声辐射力。近年来,随着生物医学材料科学迅猛发展,纳米载药系统取材更加广泛,制备方法愈发精良,载药量日益提高。将纳米载药系统与UTMD进行联合,可以扬长避短,为肿瘤等多种疾病的治疗带来新的思路与希望。本文旨在对UTMD与载药/载基因纳米粒联合应用的生物物理学机制及应用研究进行综述并提出展望。     

超声波的生物学效用及其在转基因中的应用

超声波主耍引起空化现象。超声波的生物学效用是多方面的,既可引起生物大分子以至于细胞的损伤;又可促进生物大分子的合成,加速生化反应。超声波诱导基因转移是目前发展起来的一种比较理想的转基因技术。     

关于超声组织定征的研究、应用进展

鉴于现有超声检测技术的局限性,促使人们进行超声组织定征(Ultrasonic tissue characterization)的研究、应用。超声组织定征试图通过定量提取人体组织中的有用信息,并做出解释以达到识别各种正常和病理组织并对其进行鉴别和分析的目的。由于超声通过组织的传输和反射特性的复杂性,超声和组织相互作用的机制尚     

医学超声治疗原理及其临床应用研究

本文从超声波对人体特有的生物效应出发,用生物医学工程的观点,阐述了现代超声治疗技术基本原理及最新临床应用成果,特别是在超声外科治疗技术中的最新发展,展望了超声治疗技术的应用发展前景。     

肿瘤的超声波治疗

文中就超声波热疗,高强度聚焦超声以及低频超声波在肿瘤治疗中的应用进行了描述。早期主要是利用超声波的热效应来治疗肿瘤,近年来兴起的高强度聚焦超声是热疗法的另一发展。它瞬间使肿瘤组织温度升至65℃以上,导致靶区组织凝固和坏死来达到对肿瘤的“热切除”,是一种安全、有效的肿瘤治疗手段,具有无限潜力。尽管低频超声治疗肿瘤的机制尚不明了,但因其可以诱导细胞凋亡,为肿瘤的治疗提供了新的途径,其治疗作用已受到重视。     

肿瘤的超声波治疗

文中就超声波热疗,高强度聚焦超声以及低频超声波在肿瘤治疗中的应用进行了描述。早期主要是利用超声波的热效应来治疗肿瘤,近年来兴起的高强度聚焦超声是热疗法的另一发展。它瞬间使肿瘤组织温度升至65℃以上,导致靶区组织凝固和坏死来达到对肿瘤的“热切除”,是一种安全、有效的肿瘤治疗手段,具有无限潜力。尽管低频超声治疗肿瘤的机制尚不明了,但因其可以诱导细胞凋亡,为肿瘤的治疗提供了新的途径,其治疗作用已受到重视。     

Ultrasound-biophysics mechanisms

Ultrasonic biophysics is the study of mechanisms responsible for how ultrasound and biological materials interact. Ultrasound-induced bioeffect or risk studies focus on issues related to the effects of ultrasound on biological materials. On the other hand, when biological materials affect the ultrasonic wave, this can be viewed as the basis for diagnostic ultrasound. Thus, an understanding of the interaction of ultrasound with tissue provides the scientific basis for image production and risk assessment. Relative to the bioeffect or risk studies, that is, the biophysical mechanisms by which ultrasound affects biological materials, ultrasound-induced bioeffects are generally separated into thermal and non-thermal mechanisms. Ultrasonic dosimetry is concerned with the quantitative determination of ultrasonic energy interaction with biological materials.

Whenever ultrasonic energy is propagated into an attenuating material such as tissue, the amplitude of the wave decreases with distance. This attenuation is due to either absorption or scattering. Absorption is a mechanism that represents that portion of ultrasonic wave that is converted into heat, and scattering can be thought of as that portion of the wave, which changes direction. Because the medium can absorb energy to produce heat, a temperature rise may occur as long as the rate of heat production is greater than the rate of heat removal. Current interest with thermally mediated ultrasound-induced bioeffects has focused on the thermal isoeffect concept. The non-thermal mechanism that has received the most attention is acoustically generated cavitation wherein ultrasonic energy by cavitation bubbles is concentrated. Acoustic cavitation, in a broad sense, refers to ultrasonically induced bubble activity occurring in a biological material that contains pre-existing gaseous inclusions. Cavitation-related mechanisms include radiation force, microstreaming, shock waves, free radicals, microjets and strain. It is more challenging to deduce the causes of mechanical effects in tissues that do not contain gas bodies. These ultrasonic biophysics mechanisms will be discussed in the context of diagnostic ultrasound exposure risk concerns.     

Tumor cytotoxicity in vivo and radical formation in vitro depend on the shock wave-induced cavitation dose

Local tumor therapy using focused ultrasonic waves may become an important treatment option. This technique exploits the ability of mechanical waves to induce thermal and nonthermal effects noninvasively. The cytotoxicity to cultured cells and biological tissues in vivo that results from exposure to ultrasonic shock waves is considered to be a nonthermal effect that is partly a consequence of ultrasound-induced cavitation. Cavitation is defined as the formation of bubbles during the negative wave cycle; their subsequent oscillation and/or violent implosion can affect surrounding structures. To investigate cavitational effects in cells and tissues, defined cavitation doses must be applied while ideally holding all other potential ultrasound parameters constant. The application of independent cavitation doses has been difficult and has yielded little knowledge about quantitative cavitation-tissue interactions. By using a special shock-wave pulse regimen and laser optical calibration in this study, we were able to control the cavitation dose independently of other physical parameters such as the pressure amplitudes, and averaged acoustic intensity. We treated Dunning prostate tumors (subline R3327-AT1) transplanted into Copenhagen rats with shock waves at three cavitation dose levels and then determined the tumor growth delay and the histopathological changes. All of the treated animals exhibited a significant tumor growth delay compared to the controls. Higher cavitation doses were associated with a greater delay in the growth of the tumor and more severe effects on tumor histopathology, such as hemorrhaging, tissue disruption, and necrosis. In vitro, the cavitation dose level correlated with the amount of radical formation. We concluded that the process of acoustic cavitation was responsible; higher cavitation doses caused greater effects in tumors both in vivo and in vitro. These findings may prove important in local tumor therapy and other applications of ultrasound such as ultrasound-mediated drug delivery.     

Ultrasound and matter--physical interactions

The basic physical characteristics of ultrasound waves are reviewed in terms of the typical displacements, velocities, accelerations and pressures generated in various fluid media as a function of frequency. The effects on wave propagation of interfaces are considered, and the way in which waves are reflected, transmitted and mode converted at interfaces introduced. Then the nonlinear propagation of high amplitude ultrasound is explained, and its consequences, including the generation of harmonic frequencies and enhanced attenuation, considered. The absorption of ultrasonic waves and the resulting heat deposition in absorbing media are described together with factors determining the resulting temperature rises obtained. In the case of tissue these include conduction and perfusion. The characteristics of cavitation in fluid media are also briefly covered. Finally, secondary nonlinear physical effects are described. These include radiation forces on interfaces and streaming in fluids.     

Progrès et perspectives ultrasonores

Ultrasonic waves are more and more widely used in medicine for the examination of organs by Doppler echography. The most frequently used ultrasonic frequencies range between 2 and 20 MHz. The relatively low cost and the non-invasiveness of ultrasound explain its increasing use in patients for both diagnosis and follow-up. In the near future, strong perspectives exist for the use of ultrasound for the treatment of tumours and also for local drug delivery. Several French research teams linked to university hospitals or research institutions have conducted key works for the progress of knowledge together with the development of new clinical methods. Several business units or industrial activities have been created after these works. Some landmarks will be found in this text on the features that today make the success of ultrasonic imaging and related modes, with the emphasis of the great and constantly renewed potential of creativity linked to those waves in the human body.     

The role of cavitation in liposome formation

Liposome size is a vital parameter of many quantitative biophysical studies. Sonication, or exposure to ultrasound, is used widely to manufacture artificial liposomes, yet little is known about the mechanism by which liposomes are affected by ultrasound. Cavitation, or the oscillation of small gas bubbles in a pressure-varying field, has been shown to be responsible for many biophysical effects of ultrasound on cells. In this study, we correlate the presence and type of cavitation with a decrease in liposome size. Aqueous lipid suspensions surrounding a hydrophone were exposed to various intensities of ultrasound and hydrostatic pressures before measuring their size distribution with dynamic light scattering. As expected, increasing ultrasound intensity at atmospheric pressure decreased the average liposome diameter. The presence of collapse cavitation was manifested in the acoustic spectrum at high ultrasonic intensities. Increasing hydrostatic pressure was shown to inhibit the presence of collapse cavitation. Collapse cavitation, however, did not correlate with decreases in liposome size, as changes in size still occurred when collapse cavitation was inhibited either by lowering ultrasound intensity or by increasing static pressure. We propose a mechanism whereby stable cavitation, another type of cavitation present in sound fields, causes fluid shearing of liposomes and reduction of liposome size. A mathematical model was developed based on the Rayleigh-Plesset equation of bubble dynamics and principles of acoustic microstreaming to estimate the shear field magnitude around an oscillating bubble. This model predicts the ultrasound intensities and pressures needed to create shear fields sufficient to cause liposome size change, and correlates well with our experimental data.     

Mechanism of disintegration of biological cells in ultrasonic cavitation

On the basis of elastic waves released by imploding cavitation bubbles, a mechanism for biological cell disintegration in high intensity ultrasounds has been proposed. Comparison of this mechanism with the published results on yeast cells shows many points of agreement suggesting that yeast cell disintegration in ultrasonic cavitation occurs by shear stresses developed by viscous dissipative eddies arising from shock waves.     

木质部导管空穴化研究中的几个热点问题

 导管的空穴化和栓塞化现象是目前国际上水分生理生态研究的一个热点。该文对导管空穴化和栓塞化研究中出现的几个热点问题进行了概括和总结。1）在研究导管空穴化的实验手段上,超声波传感器探测法具有一定的局限性;目前至少存在4种可能的原因来解释木质部压力探针法（XPP）和压力室法所测得的导管水柱张力不一致的现象;近来出现的核磁共振成像法可以进行导管空穴化的无损伤检测。2）导管解剖学特征与形成空穴的可能性之间的关系可能与树种相关。3）导管空穴化引起气孔关闭的作用机制目前还不太清楚。4）植物防止空穴化产生的能力与适应干旱能力之间的关系还没有定论。5）单独用根压来解释空穴化导管的重新注水机制是不全面的,还存在其它重新注水机制。     

Millimeter waves: Acoustic and electromagnetic

This article is the presentation I gave at the D'Arsonval Award Ceremony on June 14, 2011 at the Bioelectromagnetics Society Annual Meeting in Halifax, Nova Scotia. It summarizes my research activities in acoustic and electromagnetic millimeter waves over the past 47 years. My earliest research involved acoustic millimeter waves, with a special interest in diagnostic ultrasound imaging and its safety. For the last 21 years my research expanded to include electromagnetic millimeter waves, with a special interest in the mechanisms underlying millimeter wave therapy. Millimeter wave therapy has been widely used in the former Soviet Union with great reported success for many diseases, but is virtually unknown to Western physicians. I and the very capable members of my laboratory were able to demonstrate that the local exposure of skin to low intensity millimeter waves caused the release of endogenous opioids, and the transport of these agents by blood flow to all parts of the body resulted in pain relief and other beneficial effects. Bioelectromagnetics 34:3–14, 2013. © 2012 Wiley Periodicals, Inc.     

体外冲击波碎石焦点附近声压分布的时域有限差分法数值解析

泌尿系统结石症是一种多发病。体外冲击波碎石(Extracorporealshockwavelithotropisy,ESWL)法是应用人体外发射的高强度脉冲超声波在人体内的焦点附近形成的冲击波破碎结石,被破碎的结石碎片随尿液排出体外的治疗泌尿系统结石症方法。由于这种治疗方法具有非创伤等优点而被广泛地应用于泌尿系统结石症的治疗。但是,ESWL治疗过程中有时会引发尿血、肾血肿等并发症,影响其治疗效果的主要因素之一为ESWL焦点附近形成的声压分布。在这里,利用作者等以前提出的时域有限差分(finitedifferencetimedomain,FDTD)超声波非线性传播的仿真方法,数值仿真ESWL超声波非线性传播过程,研究ESWL焦点附近声压的分布、焦点区域(焦区)的大小形状、高强度超声波形成的实际焦点位置。