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Robert J. Siegel - One of the best experts on this subject based on the ideXlab platform.
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Ultrasound thrombolysis.
Ultrasonics, 2008Co-Authors: Robert J. Siegel, Huai LuoAbstract:Ultrasound Energy for thrombolysis dates back to 1976. Trubestein et al. demonstrated first in vitro that a rigid wire delivery low frequency Ultrasound Energy could disrupt clot. These investigators also showed that this system had potential for peripheral arterial clot dissolution in vivo in animal studies [G. Trubestein, C. Engel, F. Etzel, Clinical Science 51 (1976) 697s-698s]. Subsequently, four basic approaches to ultrasonic thrombolysis have been pursued--two without pharmacological agents: (1) catheter-delivered external transducer Ultrasound, (2) transcutaneous-delivered HIFU external Ultrasound without drug delivery and Ultrasound in conjunction with thrombolytic drugs and/or microbubbles or other agents, (3) Catheter-delivered transducer-tipped Ultrasound with local drug delivery, and (4) transcutaneous-delivered low frequency Ultrasound with concomitant systemic (intravenous) drug delivery for site specific Ultrasound augmentation. This article reviews recent data on therapeutic Ultrasound for thrombolysis in vitro, in vivo, in animal studies, as well as in human clinical trials.
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Noninvasive low-frequency Ultrasound Energy causes vasodilation in humans.
Journal of the American College of Cardiology, 2006Co-Authors: Kiyoshi Iida, Huai Luo, Kohsuke Hagisawa, Takashi Akima, Prediman K. Shah, Tasneem Z. Naqvi, Robert J. SiegelAbstract:Objectives We evaluated the potential vasodilator effects of transcutaneous low-frequency Ultrasound (US) in human brachial arteries. Background Recent data show that transthoracic low-frequency US Energy results in canine coronary artery vasodilation. Methods Brachial artery diameters were measured before and after low-frequency US (29 kHz, 1.4 W/cm 2 ) exposure using US imaging with a linear-array transducer. We assessed the time course of diameter changes after US in 20 subjects. In 10 of 20 subjects, brachial artery flow-mediated vasodilation (FMD) was measured to compare the effect of US to a standard method of evaluating endothelial function. Results Significant vasodilation was seen after 2 min of US compared with baseline values. At 5 min of US, the brachial artery diameter increased by 4.1%. In addition, the arteries continued to dilate after US exposure. At 3 min after US there was a 5.4%, and at 5 min after US a 6.0% increase in vessel diameter (p Conclusions This is the first study to demonstrate that noninvasive transcutaneous low-frequency US Energy dilates human brachial arteries. This arterial vasodilator effect has a rapid onset (within 2 min), lasts about 20 min, and is similar in magnitude to that of FMD. The vasodilator effect of US may have diagnostic and therapeutic potential in patients with or at risk for vascular disease.
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Ultrasound Energy improves myocardial perfusion in the presence of coronary occlusion.
Journal of the American College of Cardiology, 2004Co-Authors: Robert J. Siegel, Huai Luo, Valentina Suchkova, Takashi Miyamoto, Raymond B. Baggs, Yoram Neuman, Michael J. Horzewski, Veijo T. Suorsa, Sergio L. Kobal, Todd A. ThompsonAbstract:Objectives We evaluated whether Ultrasound improves myocardial tissue perfusion in 14 animals with coronary artery occlusion. Background A recent study demonstrated that low-frequency Ultrasound improves tissue perfusion in the rabbit ischemic limb, but there are no data on Ultrasound enhancement of myocardial perfusion. Methods Fourteen animals (9 dogs, 5 pigs) underwent thoracotomy and occlusion of a diagonal branch of the left anterior descending coronary artery. Myocardial tissue perfusion units (TPUs) and pH were measured before coronary occlusion, after occlusion, and after direct exposure of the ischemic myocardium in thepresence of fixed occlusion to low-frequency Ultrasound (27 kHz). Results The TPU decreased from 100.9 ± 13 at baseline to 71.1 ± 13 (p Conclusions Low-frequency, low-intensity Ultrasound improves myocardial tissue perfusion and pH in the presence of a fixed coronary artery occlusion.
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Augmentation of In-Vitro Clot Dissolution by Low Frequency High-Intensity Ultrasound Combined with Antiplatelet and Antithrombotic Drugs
Journal of Thrombosis and Thrombolysis, 2001Co-Authors: Shaul Atar, Yochai Birnbaum, Tomoo Nagai, Robert J. SiegelAbstract:Background: Glycoprotein IIb/IIIa antagonists and heparin are increasingly used for treatment of acute coronary syndromes. There is no data on the effect of these drugs on clot dissolution when combined with low frequency high-intensity ultrasonic Energy. We examined a possible additive effect of low frequency high-intensity Ultrasound with an antithrombotic, an antiplatelet and a fibrinolytic agent alone or in combinations for in vitro blood clot dissolution. Methods: Human blood clots were incubated for 10′, 15′ and 30′ in normal saline containing commonly used concentrations of heparin, tirofiban, t-PA and Optison (echocardiographic contrast agent) alone and in combinations. Clots were then randomly exposed to low frequency high-intensity Ultrasound (27[emsp3 ]kHz) for 5 minutes. The percent difference in clot weight and the incremental effect of Ultrasound Energy were calculated. Results: The most significant additive effect of Ultrasound Energy was detected with the combination of tirofiban and heparin (39±2% augmentation after 10′ of incubation, p
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Clinical demonstration that catheter-delivered Ultrasound Energy reverses arterial vasoconstriction.
Journal of the American College of Cardiology, 1992Co-Authors: Robert J. Siegel, Peter Gaines, A.e. Procter, Tim A. Fischell, David C. CumberlandAbstract:Abstract Objectives. This study was designed to describe the clinical effects of Ultrasound Energy on guide-wire-induced arterial vasoconstriction. Background. We have previously shown that Ultrasound Energy (20 kHz) delivered by a wire probe produces dose-dependent, endothelium-independent smooth muscle relaxation capable or reversing both receptor-mediated and voltage-dependent vasoconstriction in vitro. Methods. A high intensity, low frequency Ultrasound catheter system was used to recanalize total occlusions in the superficial femoral arteries of two patients. After recanalization, the proximal residual stenoses were each Results. After 30 and 90 s, respectively, of exposure to Ultrasound Energy with a frequency of 19.5 kHz, peak tip amplitude of 111 μm and power output at the transducer of 25 W, the vasospasm resolved in each arterial segment. Conclusions. Our findings are the first reported clinical cases documenting that catheter-delivered low frequency, high intensity Ultrasound induces arterial vasodilation at the site of vasoconstriction. These biologic effects appear to be relatively unique for an angioplasty device and may have potential clinical importance.
Mahmut Bayramoglu - One of the best experts on this subject based on the ideXlab platform.
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Graphene Synthesis by Ultrasound Energy-Assisted Exfoliation of Graphite in Various Solvents
Crystals, 2020Co-Authors: Betül Gürünlü, Çiğdem Taşdelen-yücedağ, Mahmut BayramogluAbstract:The liquid-phase exfoliation (LPE) method has been gaining increasing interest by academic and industrial researchers due to its simplicity, low cost, and scalability. High-intensity Ultrasound Energy was exploited to transform graphite to graphene in the solvents of dimethyl sulfoxide (DMSO), N,N-dimethyl formamide (DMF), and perchloric acid (PA) without adding any surfactants or ionic liquids. The crystal structure, number of layers, particle size, and morphology of the synthesized graphene samples were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), ultraviolet visible (UV–vis) spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM). XRD and AFM analyses indicated that G-DMSO and G-DMF have few layers while G-PA has multilayers. The layer numbers of G-DMSO, G-DMF, and G-PA were determined as 9, 10, and 21, respectively. By DLS analysis, the particle sizes, polydispersity index (PDI), and zeta potential of graphene samples were estimated in a few micrometers. TEM analyses showed that G-DMSO and G-DMF possess sheet-like fewer layers and also, G-PA has wrinkled and unordered multilayers.
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Graphene Synthesis by Ultrasound Energy Assisted Exfoliation of Graphite in Various Solvents
2020Co-Authors: Betül Gürünlü, Çiğdem Taşdelen-yücedağ, Mahmut BayramogluAbstract:Liquid Phase Exfoliation (LPE) method has been gaining increasing interest by academic and industrial researchers due to its simplicity, low-cost, and scalability. High intensity Ultrasound Energy was exploited to transform graphite to graphene in the solvents of dimethyl sulfoxide (DMSO), N,N-dimethyl formamide (DMF), and perchloric acid (PA) without any surfactants or ionic liquids. The crystal structure, number of layers, particle size, and morphology of the synthesized graphene samples were characterized by X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), Ultraviolet visible (UV–vis) spectroscopy, Dynamic Light Scattering (DLS), and Transmission Electron Microscopy (TEM). XRD and AFM analyses indicated that G-DMSO and G-DMF have few layers and G-PA has multilayers. The layer numbers of G-DMSO, G-DMF, and G-PA were determined as 9, 10, and 21, respectively. By DLS analysis, the particle sizes of graphene samples were estimated in a few micrometers. TEM analyses showed that G-DMSO and G-DMF possess sheet-like fewer layers and also, G-PA has wrinkled and unordered multilayers.
Katsuro Tachibana - One of the best experts on this subject based on the ideXlab platform.
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Emerging technologies in therapeutic Ultrasound: Thermal ablation to gene delivery
Human Cell, 2004Co-Authors: Katsuro TachibanaAbstract:Ultrasound is used today in medicine as a modality for diagnostic imaging. Recently, there have been numerous reports on the application of thermal and nonthermal Ultrasound Energy for treating various diseases. In addition to thermal ablation of tumors, non-thermal Ultrasound combined with drugs and genes have led to much excitement especially for cancer treatment, vascular diseases, and regenerative medicine. Ultrasound Energy can enhance the effects of thrombolytic agents such as urokinase for treatment of stroke and acute myocardial infarction. New Ultrasound technologies have resulted in advanced devices such as a) Ultrasound catheters, b) Non-invasive methods as high intensity focused Ultrasound (HIFU) in conjunction with MRI and CT is already being applied in the clinical field, c) Chemical activation of drugs by Ultrasound Energy for treatment of tumors is another new field recently termed “Sonodynamic Thew”, and d) Combination of genes and microbubble have induced great hopes for ideal gene therapy (sonoporation). Various examples of Ultrasound combined modalities are under investigation which could lead to revolutionary therapy.
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Ultrasound therapy for stroke and regenerative medicine
International Congress Series, 2004Co-Authors: Katsuro TachibanaAbstract:Abstract Ultrasound has been in use in medicine for half a century as a modality for diagnostic imaging and therapy. Recently, there have been numerous reports on the application of thermal and nonthermal Ultrasound Energy for treating various diseases in the brain. In addition to thermal ablation of brain tumors, nonthermal Ultrasound combined with drugs has led to much excitement especially for vascular diseases in the brain and regenerative medicine. Ultrasound Energy can enhance the effects of thrombolytic agents such as urokinase for treatment of stroke. Therapeutic Ultrasound catheters are currently being developed. Noninvasive methods such as high-intensity focused Ultrasound (HIFU) in conjunction with magnetic resonance image (MRI) and CT are already being applied in the clinical field. Chemical activation of drugs by Ultrasound Energy for treatment of tumors is another new field recently termed “Sonodynamic Therapy”. Combination of genes and microbubble has induced great hopes for application of gene therapy to the brain. Various examples of Ultrasound combined modalities are under investigation which could lead to revolutionary brain therapy.
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Application of Ultrasound Energy as a New Drug Delivery System
Japanese Journal of Applied Physics, 1999Co-Authors: Katsuro Tachibana, S TachibanaAbstract:Ultrasound has been in use for the last three decades as a modality for diagnostic imaging in medicine. Recently, there have been numerous reports on the application of nonthermal Ultrasound Energy for targeting or controlling drug release. This new concept of therapeutic Ultrasound combined with drugs has led to much excitement in various medical fields. Ultrasound Energy can enhance the effects of thrombolytic agents such as urokinase. Therapeutic Ultrasound catheters are currently being developed for treatment of cardiovascular diseases. Devices with Ultrasound transducers implanted in transdermal drug patches are also being evaluated for possible delivery of insulin through the skin. Chemical activation of drugs by Ultrasound Energy for treatment of cancers is another new field recently termed "Sonodynamic Therapy". Various examples of Ultrasound application are under investigation which could lead to revolutionary drug delivery systems in the future.
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Ultrasound activation of new drugs for killing cancer cells
The Journal of the Acoustical Society of America, 1998Co-Authors: Katsuro Tachibana, Toshiki UchidaAbstract:The study of the destructive action of Ultrasound in conjunction with drugs upon cancer has become an exciting area. New substances that are chemically activated by low level Ultrasound Energy have recently been discovered [Tachibana et al., Lancet 349, 325 (1997)]. Three nontoxic red stains frequently used for cosmetics and food, Rose Bengal, Eosin Y, and Erythrosine B were evaluated if cytotoxic effects can be induced by Ultrasound Energy in vitro. Gastric and leukemic cancer cell line suspensions were exposed to Ultrasound (1 MHz) with or without the drugs. The survival rate of the cells was measured immediately after treatment. The temperature increase was less than 2 °C. Treatment with Ultrasound plus drugs resulted in a significant reduction of the survival rate compared to Ultrasound alone. Whereas the drug alone showed no change in survival rate. Although the mechanism is unclear, it is postulated that Ultrasound Energy, possibly cavitation, activated these drugs. Further experiments should be car...
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Enhancement of Fibrinolysis with Ultrasound Energy
Journal of Vascular and Interventional Radiology, 1992Co-Authors: Katsuro TachibanaAbstract:The effect of Ultrasound Energy on fibrinolysis of artificial thrombus in vitro was investigated. Thrombi produced by the Chandler loop method were exposed to low-Energy Ultrasound (5,000–6,000 Pa) in an Ultrasound bath (48 kHz) for 60 seconds. Fibrinolysis with urokinase was enhanced from 40.6% ± 1.8% to 59.2% ± 2.6% (mean ± standard deviation) with Ultrasound exposure after a 60-minute incubation. Ultrasound alone without urokinase resulted in no fibrinolysis. In a second experiment, a newly developed miniature Ultrasound-emitting ceramic element (2 × 1 × 5 mm) was attached to the tip of a catheter. Ultrasound exposure (225 kHz) from this device markedly enhanced fibrinolysis with urokinase from 8.9% ± 1.5% to 37.3% ± 0.8% (total Ultrasound exposure 60 seconds, intensity 30 mW/cm 2 ) after a 30-minute incubation. After a 120-minute incubation, fibrinolysis with Ultrasound exposure was 61.1% ± 1.8% versus 46.7% ± 0.5% for the unexposed group. Ultrasound enhancement of fibrinolysis was less pronounced with longer incubation time (60 or 120 minutes). Ultrasound Energy enhanced fibrinolysis with urokinase, especially in the early phase of lysis. This new device may shorten the time needed to complete fibrinolysis and reduce total drug dosage needed for treatment of thromboembolic diseases.
Betül Gürünlü - One of the best experts on this subject based on the ideXlab platform.
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Graphene Synthesis by Ultrasound Energy-Assisted Exfoliation of Graphite in Various Solvents
Crystals, 2020Co-Authors: Betül Gürünlü, Çiğdem Taşdelen-yücedağ, Mahmut BayramogluAbstract:The liquid-phase exfoliation (LPE) method has been gaining increasing interest by academic and industrial researchers due to its simplicity, low cost, and scalability. High-intensity Ultrasound Energy was exploited to transform graphite to graphene in the solvents of dimethyl sulfoxide (DMSO), N,N-dimethyl formamide (DMF), and perchloric acid (PA) without adding any surfactants or ionic liquids. The crystal structure, number of layers, particle size, and morphology of the synthesized graphene samples were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), ultraviolet visible (UV–vis) spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM). XRD and AFM analyses indicated that G-DMSO and G-DMF have few layers while G-PA has multilayers. The layer numbers of G-DMSO, G-DMF, and G-PA were determined as 9, 10, and 21, respectively. By DLS analysis, the particle sizes, polydispersity index (PDI), and zeta potential of graphene samples were estimated in a few micrometers. TEM analyses showed that G-DMSO and G-DMF possess sheet-like fewer layers and also, G-PA has wrinkled and unordered multilayers.
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Graphene Synthesis by Ultrasound Energy Assisted Exfoliation of Graphite in Various Solvents
2020Co-Authors: Betül Gürünlü, Çiğdem Taşdelen-yücedağ, Mahmut BayramogluAbstract:Liquid Phase Exfoliation (LPE) method has been gaining increasing interest by academic and industrial researchers due to its simplicity, low-cost, and scalability. High intensity Ultrasound Energy was exploited to transform graphite to graphene in the solvents of dimethyl sulfoxide (DMSO), N,N-dimethyl formamide (DMF), and perchloric acid (PA) without any surfactants or ionic liquids. The crystal structure, number of layers, particle size, and morphology of the synthesized graphene samples were characterized by X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), Ultraviolet visible (UV–vis) spectroscopy, Dynamic Light Scattering (DLS), and Transmission Electron Microscopy (TEM). XRD and AFM analyses indicated that G-DMSO and G-DMF have few layers and G-PA has multilayers. The layer numbers of G-DMSO, G-DMF, and G-PA were determined as 9, 10, and 21, respectively. By DLS analysis, the particle sizes of graphene samples were estimated in a few micrometers. TEM analyses showed that G-DMSO and G-DMF possess sheet-like fewer layers and also, G-PA has wrinkled and unordered multilayers.
Kullervo Hynynen - One of the best experts on this subject based on the ideXlab platform.
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Thermal effects of focused Ultrasound Energy on bone tissue.
Ultrasound in medicine & biology, 2001Co-Authors: N.b. Smith, J.m. Temkin, F. Shapiro, Kullervo HynynenAbstract:The effects of focused Ultrasound (US) at therapeutic acoustic power levels were studied in vivo on the bone-muscle interface in rabbit thighs. The purpose of this study was to provide direction in establishing safety guidelines for treating tissue masses using focused US on or near bone. A positioning device was used to manipulate a focused US transducer (1.5 MHz) in a magnetic resonance imaging (MRI) scanner. This system was used to sonicate the femurs of 10 rabbits at acoustic power levels of 26, 39, 52 and 65 W for 10 s. The rabbits were euthanized either 4 h or 28 days after the sonications and the bone samples were harvested for histology examinations. In the femurs studied, acoustic power levels from 39 to 65 W resulted in soft tissue damage characterized grossly by coagulated tissue and bone damage depicted by yellow discoloration. Histologic examination of lesions from sonications from 39 to 65 W demonstrated that osteocyte damage and necrosis, characterized by pyknotic cells and empty lacunae, occurred within the ablation area extending through the bone. The follow-up MR images demonstrated an increase in the amount of damage in the femurs at 28 days posttreatment in comparison to images taken immediately after treatment. Focused US directed at the femur caused immediate significant thermal damage to bone in the form of osteocyte necrosis extending through the (approximately) 1 cm bone in this study. The results suggest that, when focused US Energy is directed at or near bone-muscle interfaces, precautions should be taken to avoid thermal damage to the bone that can compromise its strength for extended periods.
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Application of Ultrasound Energy for intracardiac ablation of arrhythmias
European heart journal, 1995Co-Authors: J. E. Zimmer, Kullervo Hynynen, F. I. Carcus, Anthony C. Caruso, Louis F. Lampe, Maria L. AguirreAbstract:Ultrasound is a potential Energy source for cardiac ablation. Small Ultrasound applicators were tested for their ability to create lesions in cardiac tissue. Ultrasound applicators were designed, constructed and tested in canine cardiac tissue in degassed normal saline, and both in vitro and in vivo, lesions were produced by using transducers with frequencies of about 10 MHz. Lesion depth increased with longer duration of Energy delivery from 15-60 s, and there was a linear relationship between increasing power and depth of lesions. Seven in vivo experiments in open-chest dogs were performed, and the Ultrasound transducers were mounted on the tip of 7-French angiographic catheters. On the epicardium the maximum lesion depth was 9 mm. When the transducer was inserted into the left ventricle, lesions of 8.7 +/- 2.9 mm (n = 4) were produced. It is concluded that an Ultrasound transducer mounted on a cardiac catheter can produce lesions that may be useful for ablation of cardiac arrhythmias.
