Low-intensity ultrasound increases endothelial cell nitric oxide synthase activity and nitric oxide synthesis

Low intensity transcranial ultrasound stimulation induces hemodynamic responses through neurovascular coupling

Collective studies have demonstrated that transcranial ultrasound stimulation (TUS) can elicit activation in hemodynamics, implying its potential in treating cerebral or peripheral vessel-related malfunction. The theory for hemodynamic response to TUS is neurovascular coupling (NVC) following the ultrasound-induced cellular (de)polarization. However, it was not conclusive due to the co-existence of the pathway of direct ultrasound-vessel interactions. This study thus aims to investigate and provide direct evidence for NVC pathway in a rodent model of TUS by inhibiting neural activity with sodium valproate (VPA), a GABAergic agent. Twenty Sprague-Dawley rats were randomly assigned to VPA and Saline groups. Microelectrode and optical imaging were utilized to record local field potential and relative cerebral blood flow (rCBF) during baseline, before, and after TUS periods. We found the attenuated neural activity was associated with reduced rCBF responses. These results provided direct evidence for the presence of NVC pathway in hemodynamic modulation by TUS.

Low-intensity pulsed ultrasound improves symptoms in patients with Buerger disease: a double-blinded, randomized, and placebo-controlled study

Here we report the effects of low-intensity pulsed ultrasound (LIPUS) on symptoms in peripheral arterial disease patients with Buerger disease. A double-blinded and randomized study with active and inactive LIPUS was conducted. We assessed symptoms in leg circulation during a 24-week period of LIPUS irradiation in 12 patients with Buerger disease. Twelve patients without LIPUS irradiation served as controls. The pain intensity on visual analog score was significantly decreased after 24-week LIPUS treatment. Skin perfusion pressure was significantly increased in patients who received LIPUS treatment. There was no significant difference in symptoms and perfusion parameters in the control group. No severe adverse effects were observed in any of the patients who underwent LIPUS treatment. LIPUS is noninvasive, safe and effective option for improving symptoms in patients with Buerger disease.

Efficacy and safety of a home-use handheld multi-energy-based device for skin rejuvenation: clinical, ex vivo, and histological studies

Alongside increases in the average lifespan and a growing interest in anti-aging remedies, the demand for at-home skincare devices is rapidly expanding in the cosmetic market. This study aimed to assess the safety and efficacy of a novel home-use handheld multi-energy-based device for skin rejuvenation that simultaneously emits low level light, low-dose radiofrequency, low-energy microcurrent, and low-intensity ultrasonic wave. This prospective, randomized, split-face clinical trial enrolled 36 healthy Korean women. After 8 weeks of device use, parameters associated with skin aging were assessed. Additionally, a preliminary ex vivo study and skin biopsy following device use were performed to confirm safety and efficiency of the device. Parameters associated with skin aging including skin hydration, elasticity, roughness, skin pore size, and eye wrinkle volume showed significant improvements after 8 weeks of the device use, relative to baseline measurements and the control side. No adverse effects were observed during the follow-up period. Results of ex vivo and in vivo skin tissue studies correlated with clinical findings, which showed an increase in the expression of type 1 collagen and a decrease in the expression of matrix metalloproteinase-1, which is related to the skin aging phenotype. The expression of loricrin and involucrin, major components of the epidermal skin barrier, also increased after the use of the device. Multi-energy-based device is effective for skin rejuvenation and tolerable, without any considerable adverse effects.

The exact phenomenon and early signaling events of the endothelial cytoskeleton response to ultrasound

Low-intensity ultrasound can be applied for medical imaging and disease treatment in clinical and experimental studies. However, the biological effects of ultrasound on blood vessels, especially endothelial cells (ECs) are still unclear. In this study, the laws of endothelial cytoskeleton changes under ultrasound induction are investigated. ECs are exposed to low-intensity ultrasound, and the cytoskeletal morphology is analyzed by a filamentous (F)-actin staining technique. We further analyze the characteristics of cytoskeleton rupture using indirect immunofluorescence techniques and cytoskeleton electron microscopy. Finally, the biological effects induced by ultrasound at the tissue level are investigated in an ex vivo blood-vessel model. Significant changes in cytoskeletal structure are detected when induced by ultrasound, including cytoskeletal rupture, blebbing and apoptosis. Moreover, a temporal threshold of ECs injury under different ultrasonic intensities is established. This study illustrates a pattern of significant changes in the cytoskeletal structure of ECs induced by ultrasound. The finding serves as a guide for selecting a safe threshold for clinical ultrasound applications.

Vascular Response to Low-intensity Ultrasound Stimulation

Low-intensity ultrasound stimulation (LIUS) is an emerging neuro- and vascular-modulation technique. Studies on humans and animals have shown that LIUS could induce changes in neuronal oscillations or blood flow. However, it is still inconclusive whether the hemodynamic response to LIUS is due to neurovascular coupling (NVC), direct ultrasound-vessel interactions, or both. This study aims to detect the direct effect of LIUS on vessels using optical imaging. Fluorescence images with indocyanine green (ICG) were used to identify and quantify the morphological change in the auricle vessels of rats. Diameters of vessels were measured before, during, and post LIUS. The results indicated that LIUS could significantly increase the vessel diameters (p = 0.031). Further exploratory analysis showed that vessel dilation occurred among the majority of randomly selected vessels (i.e., 21/30 animals (70%), dilation: 6.84±1.95µm, 95% CI: [3.02,10.66]), with a significant confounding effect of the vessel size. The results provided indirect evidence for two distinct pathways in LIUS-based neurovascular modulation, i.e., the NVC and the direct ultrasound-vessel interactions.

Effects of therapeutic ultrasound on the endothelial function of patients with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is characterized by endothelial dysfunction that causes micro- and macrovascular complications. Low intensity therapeutic ultrasound (LITUS) may improve endothelial function, but its effects have not been investigated in these patients. The aim of our study was to compare the effects of pulsed (PUT) and continuous (CUT) waveforms of LITUS on the endothelium-dependent vasodilation of T2DM patients. The present randomized crossover trial had a sample of twenty-three patients (7 men) diagnosed with T2DM, 55.6 (±9.1) years old, with a body mass index of 28.6 (±3.3) kg/m2. All patients were randomized and submitted to different waveforms (Placebo, CUT, and PUT) of LITUS and the arterial endothelial function was evaluated. The LITUS of 1 MHz was applied in pulsed (PUT: 20% duty cycle, 0.08 W/cm2 SATA), continuous (CUT: 0.4 W/cm2 SPTA), and Placebo (equipment off) types of waves during 5 min on the brachial artery. Endothelial function was evaluated using the flow-mediated dilation (FMD) technique. PUT (mean difference 2.08%, 95% confidence interval 0.65 to 3.51) and CUT (mean difference 2.32%, 95% confidence interval 0.89 to 3.74) increased the %FMD compared to Placebo. In the effect size analysis, PUT (d=0.65) and CUT (d=0.65) waveforms presented moderate effects in the %FMD compared to Placebo. The vasodilator effect was similar in the different types of waves. Pulsed and continuous waveforms of LITUS of 1 MHz improved the arterial endothelial function in T2DM patients.

Do ultrasound form spontaneously nitrous pigments in nitrite-free pork meat batter?

The effects of ultrasound (US) on myoglobin modification, nitrous pigment formation, color, and total and free sulfhydryl content in nitrite-free pork meat batter were assessed. Five treatments were elaborated: Control (without US); TUS10'12 and TUS20'12 (sonication at 25 kHz, at 12 °C for 10 and 20 min, respectively); TUS10'18 and TUS20'18 (sonication at 25 kHz, at 18 °C for 10 and 20 min, respectively). Sonication for 20 min at 12 °C increased OxyMb and DeoxyMb pigments while reducing MetMb levels. This US condition also yielded higher red color indices and lower yellow color indices. Moreover, TUS20'12 exhibited enhanced nitrous pigment formation and decreased FerrylMb and free sulfhydryl (SH) values, indicating reduced oxidation in OxyMb and DeoxyMb pigments. In conclusion, the findings demonstrate that US can impart a cured color to nitrite-free meat products.

Low intensity focused ultrasound: a new prospect for the treatment of Parkinson's disease

Background: As a chronic and progressive neurodegenerative disease, Parkinson's disease (PD) still lacks effective and safe targeted drug therapy. Low-intensity focused ultrasound (LIFU), a new method to stimulate the brain and open the blood-brain barrier (BBB), has been widely concerned by PD researchers due to its non-invasive characteristics.Methods: PubMed was searched for the past 10 years using the terms 'focused ultrasound', 'transcranial ultrasound', 'pulse ultrasound', and 'Parkinson's disease'. Relevant citations were selected from the authors' references. After excluding articles describing high-intensity focused ultrasound or non-Parkinson's disease applications, we found more than 100 full-text analyses for pooled analysis.Results: Current preclinical studies have shown that LIFU could improve PD motor symptoms by regulating microglia activation, increasing neurotrophic factors, reducing oxidative stress, and promoting nerve repair and regeneration, while LIFU combined with microbubbles (MBs) can promote drugs to cross the BBB, which may become a new direction of PD treatment. Therefore, finding an efficient drug carrier system is the top priority of applying LIFU with MBs to deliver drugs.Conclusions: This article aims to review neuro-modulatory effect of LIFU and the possible biophysical mechanism in the treatment of PD, summarize the latest progress in delivering vehicles with MBs, and discuss its advantages and limitations.

Effect of Photo-Mediated Ultrasound Therapy on Nitric Oxide and Prostacyclin from Endothelial Cells

Several studies have investigated the effect of photo-mediated ultrasound therapy (PUT) on the treatment of neovascularization. This study explores the impact of PUT on the release of the vasoactive agents nitric oxide (NO) and prostacyclin (PGI₂) from the endothelial cells in an in vitro blood vessel model. In this study, an in vitro vessel model containing RF/6A chorioretinal endothelial cells was used. The vessels were treated with ultrasound-only (0.5, 1.0, 1.5 and 2.0 MPa peak negative pressure at 0.5 MHz with 10% duty cycle), laser-only (5, 10, 15 and 20 mJ/cm² at 532 nm with a pulse width of 5 ns), and synchronized laser and ultrasound (PUT) treatments. Passive cavitation detection was used to determine the cavitation activities during treatment. The levels of NO and PGI₂ generally increased when the applied ultrasound pressure and laser fluence were low. The increases in NO and PGI₂ levels were significantly reduced by 37.2% and 42.7%, respectively, from 0.5 to 1.5 MPa when only ultrasound was applied. The increase in NO was significantly reduced by 89.5% from 5 to 20 mJ/cm², when only the laser was used. In the PUT group, for 10 mJ/cm² laser fluence, the release of NO decreased by 76.8% from 0.1 to 1 MPa ultrasound pressure. For 0.5 MPa ultrasound pressure in the PUT group, the release of PGI₂ started to decrease by 144% from 15 to 20 mJ/cm² laser fluence. The decreases in NO and PGI₂ levels coincided with the increased cavitation activities in each group. In conclusion, PUT can induce a significant reduction in the release of NO and PGI₂ in comparison with ultrasound-only and laser-only treatments.

Low-Intensity Continuous Ultrasound Therapies—A Systematic Review of Current State-of-the-Art and Future Perspectives

Therapeutic ultrasound has been studied for over seven decades for different medical applications. The versatility of ultrasound applications are highly dependent on the frequency, intensity, duration, duty cycle, power, wavelength, and form. In this review article, we will focus on low-intensity continuous ultrasound (LICUS). LICUS has been well-studied for numerous clinical disorders, including tissue regeneration, pain management, neuromodulation, thrombosis, and cancer treatment. PubMed and Google Scholar databases were used to conduct a comprehensive review of all research studying the application of LICUS in pre-clinical and clinical studies. The review includes articles that specify intensity and duty cycle (continuous). Any studies that did not identify these parameters or used high-intensity and pulsed ultrasound were not included in the review. The literature review shows the vast implication of LICUS in many medical fields at the pre-clinical and clinical levels. Its applications depend on variables such as frequency, intensity, duration, and type of medical disorder. Overall, these studies show that LICUS has significant promise, but conflicting data remain regarding the parameters used, and further studies are required to fully realize the potential benefits of LICUS.

Ultrasound therapy for treatment of lower extremity intermittent claudication

BACKGROUND

While often thought of as a diagnostic tool, ultrasound (US) can also potentially be used as a therapeutic modality. US applies mechanical stress on endothelial cells and induces nitric oxide synthase, which regulates the secretion of nitric oxide, a potent vasodilator. In animal ischemic models, US has been shown to improve hindlimb, myocardial, and cerebral perfusion. We performed a pilot trial of US therapy in the lower extremities of human subjects with intermittent claudication.

METHODS

10 subjects (5 male, 5 female, mean age 69.7 ± 10.3) with intermittent claudication were recruited. Both legs were placed in a specially designed boot with a water interface between US transducers and the legs. Subjects underwent pulsed US therapy at 250 kHz frequency for 30 min for three treatments a week for six weeks. Pre and post treatment ankle:brachial index (ABI), 6-min walk (6 MW), Walking Impairment Questionnaire (WIQ), and Short Form 36 (SF36) were performed. Pre and post-treatment results were compared with paired t-test.

RESULTS

Six minute walking distance at baseline was 352 ± 70 m, after one treatment session 353 ± 70 m (p = 0.99), and at completion 372 ± 71 m (p = 0.015). There was a trend toward improved ABI after 6 weeks of treatment (0.53 ± 0.17 vs 0.64 ± 0.12, p = 0.083). After six weeks, significant improvements were noted in overall WIQ score (2.00 ± 1.48 vs 2.63 ± 1.38, p = 0.0001), WIQ (distance) 2.07 ± 1.54 vs 2.73 ± 1.42 (p = 0.036), and WIQ (stair) 2.00 ± 1.67 vs 2.62 ± 1.24, p = 0.034, with a trend in WIQ (speed), 1.89 ± 1.26 vs 2.46 ± 1.43, p = 0.069. In the SF-36, significant improvements were noted in the domains of physical functioning (44.0 ± 41.6 vs 50.5 ± 41.1, p = 0.009) and role limitations - physical (35.0 ± 48.3 vs 60.0 ± 49.6, p = 0.006) after six weeks.

CONCLUSIONS

Therapeutic US is a potential noninvasive treatment for intermittent claudication. Pilot study patients noted significant improvements in 6 MW and WIQ results after 6 weeks of treatment. A nonsignificant improvement in ABI was noted. Further research will be needed to clarify optimal treatment frequency and duration.

Hypotension and Bradycardia Produced by Transthoracic Application of Low-Intensity Ultrasound Therapy in Hearts of Healthy Rats - A Preclinical Study

Objective

To investigate the cardiovascular effects produced by transthoracic application of low-intensity pulsed ultrasound therapy (LIPUST).

Methods

Three-month-old male Wistar rats (± 300 g, N=16) were randomly allocated in two groups, namely SHAM (control group, faked procedures) and UST (animals treated with LIPUST). These animals, under anesthesia, were instrumented (femoral artery and vein catheterization) for hemodynamic recordings (mean blood pressure [MBP], heart rate [HR]) and blood biochemical profile (lipids, creatine kinase-myocardial band [CK-MB]). Then, LIPUST (spatial average-temporal average [ISATA] 1-MHz, power 0.1 to 1.2 W/cm2, pulsed 2:8 ms, cycle at 30%, for three minutes) was applied to animals from the UST group, externally to their thorax. SHAM animals were equally manipulated, but without application of ultrasound energy. After the hemodynamic and biochemical measurements, animals were sacrificed, and their hearts were mounted in a Langendorff apparatus for coronary reactivity evaluation. Standard histology techniques were employed to analyze the hearts.

Results

LIPUST application caused statistically significant reductions in MBP (92±4 vs. 106±1 mmHg) and HR (345±14 vs. 380±17 rpm) when compared with SHAM procedures. UST rats exhibited higher CK-MB levels (318±55 vs. 198±26 U/dL) and lower plasma triglycerides levels (38±7 vs. 70±10 mg/dL) than SHAM animals. Coronary reactivity was not significantly changed by LIPUST. Cardiac histopathology showed an increase in capillary permeability in treated animals when compared with SHAM animals.

Conclusion

Noninvasive LIPUST induces significant metabolic and hemodynamic changes, including intensity-dependent bradycardia and hypotension, indicating a possible therapeutic effect for cardiac events.

Effect of Low-Frequency Therapeutic Ultrasound on Induction of Nitric Oxide in CKD: Potential to Prevent Acute Kidney Injury

Introduction

Post-contrast acute kidney injury (PC-AKI) develops in a significant proportion of patients with CKD after invasive cardiology procedures and is strongly associated with adverse outcomes.

Objective

We sought to determine whether increased intrarenal nitric oxide (NO) would prevent PC-AKI.

Methods

To create a large animal model of CKD, we infused 250 micron particles into the renal arteries in 56 ± 8 kg pigs. We used a low-frequency therapeutic ultrasound device (LOTUS - 29 kHz, 0.4 W/cm²) to induce NO release. NO and laser Doppler probes were used to assess changes in NO content and blood flow. Glomerular filtration rate (GFR) was measured by technetium-diethylene-triamine-pentaacetic acid (Tc-99m-DTPA) radionuclide imaging. PC-AKI was induced by intravenous infusion of 7 cm³/kg diatrizoate. In patients with CKD, we measured GFR at baseline and during LOTUS using Tc-99m-DTPA radionuclide imaging.

Results

In the pig model, CKD developed over 4 weeks (serum creatinine [Cr], mg/dL, 1.0 ± 0.2-2.6 ± 0.9, p < 0.01, n = 12). NO and renal blood flow (RBF) increased in cortex and medulla during LOTUS. GFR increased 75 ± 24% (p = 0.016, n = 3). PC-AKI developed following diatrizoate i.v. infusion (Cr 2.6 ± 0.7 baseline to 3.4 ± 0.6 at 24 h, p < 0.01, n = 3). LOTUS (starting 15 min prior to contrast and lasting for 90 min) prevented PC-AKI in the same animals 1 week later (Cr 2.5 ± 0.4 baseline to 2.6 ± 0.7 at 24 h, p = ns, n = 3). In patients with CKD (n = 10), there was an overall 25% increase in GFR in response to LOTUS (p < 0.01).

Conclusions

LOTUS increased intrarenal NO, RBF, and GFR and prevented PC-AKI in a large animal model of CKD, and significantly increased GFR in patients with CKD. This novel approach may provide a noninvasive nonpharmacological means to prevent PC-AKI in high-risk patients.

Ultrasound therapy with optimal intensity facilitates peripheral nerve regeneration in rats through suppression of pro-inflammatory and nerve growth inhibitor gene expression

Background

Therapeutic ultrasound (US) is a promising physical therapy modality for peripheral nerve regeneration. However, it is necessary to identify the most effective US parameters and clarify the underlying mechanisms before its clinical application. The intensity of US is one of the most important parameters. However, the optimum intensity for the promotion of peripheral nerve regeneration has yet to be determined.

Objectives

To identify the optimum intensity of US necessary for the promotion of peripheral nerve regeneration after crush injuries in rats and to clarify the underlying mechanisms of US by mRNA expression analysis.

Methods

We inflicted sciatic nerve crush injuries on adult Lewis rats and performed ultrasound irradiation using 4 different US intensities: 0 (sham stimulation), 30, 140, and 250 mW/cm² with frequency (5 days/week) and duration (5 min/day). We evaluated peripheral nerve regeneration by quantitative real-time PCR one week after injury. Histomorphometric analyses and motor function analysis were evaluated 3 weeks after injury.

Results

US stimulation enhanced re-myelination as well as sprouting of axons, especially at an intensity of 140 mW/cm². mRNA expression revealed that US suppressed the expression of the inflammatory cytokines TNF and IL-6 and the axonal growth inhibitors SEMA3A and GSK3β.

Conclusions

An intensity of 140 mW/cm² was optimal to support regeneration of the sciatic nerve after a crush injury in rats by, in part, the suppression of pro-inflammatory and nerve growth inhibitor gene expression.

Intensity-dependent effect of pulsed and continuous therapeutic ultrasound on endothelial function: a randomised crossover clinical trial

Background/Aims

The aim of this study was to evaluate the effects of different intensities and waveforms of therapeutic ultrasound on endothelial function in typically healthy participants.

Methods

A total of 15 participants were evaluated over 2 consecutive days. Different intensities of continuous and pulsed (20% duty cycle) 1-MHz ultrasound were applied to the brachial artery for 5 minutes each. Endothelial function was measured using flow-mediated dilation technique before and immediately after ultrasound was applied.

Results

Compared to baseline values, endothelium-dependent vasodilation increased with both continuous (2.8%) and pulsed (1.6%) ultrasound at an intensity of 0.4 W/cm2SPTA. At 1.2 W/cm2SPTA, endothelium-dependent vasodilation was 4.1% above baseline for pulsed and 5.3% above baseline for continuous waveforms. There was no additional increase in vasodilation at intensities above 1.2 W/cm2SPTA. The percentage of endothelium-dependent vasodilation was similar for the all of the different waveforms studied.

Conclusions

Both continuous and pulsed ultrasound waveforms promote endothelium-dependent vasodilation. There was a dose-dependent increase in vasodilation at intensities from 0.4 W/cm2SPTA to 1.2 W/cm2SPTA. Pulsed is more efficient than continuous ultrasound because it produces the same effect on endothelium-dependent vasodilation while employing 20% of the energy applied with continuous ultrasound.

A neuroprotective brain stimulation for vulnerable cerebellar Purkinje cell after ischemic stroke: a study with low-intensity focused ultrasound

The role of established contralateral cerebrocerebellar connections on cerebellar injury during stroke has been increasingly revealed in recent years. An extensive number of studies have investigated alteration in inter-hemispheric correlation in order to find brain regions whose responses are specific to restore functional loss and enhance adaptive neural plasticity after stroke. Although, several non-invasive brain stimulation studies have proven their efficacy in the treatment of stroke recovery, finding more effective brain regions that responsible for stroke rehabilitation as well as optimizing neural stimulation protocol are the main goals of further investigations. In this study, the lateral cerebellar nucleus (LCN) was exposed to Low-Intensity Focused Ultrasound (LIFU) to reduce the cerebellar damage resulting from crossed cerebellar diaschisis (CCD) phenomenon after cerebral ischemia. A mouse brain ischemia was induced by middle cerebral artery occlusion (MCAO). A level of decrease in Purkinje cell (PC) number and a quantity of myeloperoxidase (MPO) positive neutrophils in the cerebral cortex were compared between stroke and stroke+LIFU groups after MCAO. In stroke+LIFU group, the increased ipsilateral water content due to tissue swelling was observed, showing an attenuation of brain edema. Prominently, the reduction of the neuroimmune reactivity at the infarct core and the peri-infarct regions, and the increased rate of survival among PCs clearly demonstrated primary evidence of neuroprotective effect induced by LIFU-mediated cerebellar modulation.

Ultrasound-assisted debridement of neuroischaemic diabetic foot ulcers, clinical and microbiological effects: a case series

OBJECTIVE

To evaluate the clinical and microbiological effects of sequential wound debridement in a case series of neuroischaemic diabetic foot ulcers (DFUs) using an ultrasound-assisted wound debridement (UAW) device.

METHOD

A prospective, single-centre study, involving a case series of 24 neuroischaemic DFUs, was conducted to evaluate sequential wound debridement with UAW during a six-week treatment period. Soft tissue punch biopsies were taken every second week of treatment, both before and after wound debridement sessions. Qualitative and quantitative microbiological analysis was performed and wounds were assessed at patient admission, and before and after each debridement procedure.

RESULTS

Wound tissue quality scores improved significantly from a mean score of 2.1±1.3 points at patient inclusion, to 5.3±1.7 points (p=0.001). Mean wound sizes were 4.45cm² (range: 2-12.25cm²) at week zero, and 2.75cm² (range: 1.67-10.70cm²) at week six (p=0.04). The mean number of bacterial species per culture determined at week zero and at week six was 2.53±1.55 and 1.90±1.16, respectively (p=0.023). Wound debridement resulted in significant decreases in bacterial counts (1.17, 1.31 and 0.77 log units in colony forming units (CFU) for week zero, three and six, respectively). The average bacterial load in tissue samples before and after wound debridement after the six-week treatment was Log 5.55±0.91CFU/g and Log 4.59±0.89CFU/g, respectively (p<0.001).

CONCLUSIONS

The study results showed a significant bacterial load reduction in DFU tissue samples as a result of UAW debridement, independent of bacterial species, some of which exhibited antibiotic-resistance. Significant bacterial load reduction was correlated with improved wound conditions and significant reductions of wound size.

[Morphological justification of the effectiveness of ultrasonic cavitation with 0.2]

AIM

Structural and functional analysis of cells from purulent-necrotic wounds in patients with diabetic foot syndrome undergoing ultrasonic treatment with 0.2% Lavasept solution.

MATERIAL AND METHODS

It is presented morphological/ultrastructural analysis of wound specimens in 90 (DFS) patients aged 27-80 years with diabetic foot syndrome and purulent-necrotic complications who were hospitalized in the department of wounds and wound infections of the Vishnevsky Institute of Surgery in 2013-2016. Main group consisted of 75 patients, control group - 15 patients. Mean age was 58.4±8.2 years. All patients had diabetes mellitus type II for previous 13±4.5 years. Severity of foot tissue damage was assessed according to Wagner classification (F. Wagner, 1981). 46 (51.1%) patients had Wagner III-IV, 44 (48.9%) patients - Wagner II. Complex treatment included radical surgical management of purulent lesion, surgical revascularization for critical limb ischemia and foot reconstruction at the final stage. Additional measures were complete unloading of the foot, correction of carbohydrate metabolism and concomitant diseases. Topical treatment between surgical stages included dressing with 1.0% betadine solution (once a day). Ultrasonic cavitation was additionally applied in the main group. Electron microscopic examination of specimens was used before treatment, after 3-5 and 7-10 days in order to assess effectiveness of ultrasound cavitation for purulent-necrotic complications of DFS.

RESULTS

Ultrasound cavitation with 0.2% Lavasept solution effectively cleans wounds from microbial and cellular detritus, destroys cellular membranes of biofilm-forming microorganisms, prevents their redo development and reinfection of the wound. Effective management of the wounds accelerates reparative processes that allows to perform foot reconstruction early.

Therapeutic Ultrasound Increases Myocardial Blood Flow in Ischemic Myocardium and Cardiac Endothelial Cells: Results of In Vivo and In Vitro Experiments

BACKGROUND

Therapeutic ultrasound can reduce infarct size in a model of coronary thrombosis even when sonothrombolysis is ineffective. The aim of this study was to test the hypothesis that ultrasound-induced cardioprotection is mediated by molecules released from the vascular endothelium that increase myocardial blood flow (MBF) and also have direct tissue-salvaging effects.

METHODS

In vivo and in vitro experiments were performed using a 1.05-MHz transducer. For the in vivo experiments 10 control and 10 ultrasound-treated dogs undergoing occlusion of the left anterior descending coronary artery were studied. MBF was measured using myocardial contrast echocardiography. For the in vitro experiments, primary mouse cardiac endothelial cells were exposed to ultrasound at baseline or following oxygen-glucose deprivation and endothelial nitric oxide synthase phosphorylation as well as adenosine and the eicosanoids epoxyeicosatrienoic acids, dihydroxyeicosatrienoic acids, and hydroxyl-eicosatetraenoic acids were measured.

RESULTS

In vivo, ultrasound treatment caused higher MBF (20 ± 10 vs 10 ± 8, P = .03) and higher wall thickening (3 ± 3% vs 1 ± 0.4%, P = .01) in the collateral-derived border zone compared with control. Epicardial MBF in the left anterior descending coronary artery bed also tended to be higher (17 ± 17 vs 5 ± 4, P = .05) in ultrasound-treated versus control animals; however, endocardial MBF in this region was similar to that in controls (13 ± 14 vs 14 ± 7). In vitro, phosphorylated endothelial nitric oxide synthase and adenosine increased (by 129 ± 11% and 286 ± 63%, respectively, P < .01) with ultrasound compared with unstimulated cells. Similar results were obtained with epoxyeicosatrienoic acids. After oxygen-glucose deprivation, phosphorylated endothelial nitric oxide synthase decreased and was restored with application of ultrasound. Similar changes were noted with epoxyeicosatrienoic acids. Cell viability decreased with oxygen-glucose deprivation and returned to near baseline with ultrasound.

CONCLUSIONS

Ultrasound increases MBF in ischemic tissue in vivo. This effect is likely mediated by the release of a plethora of coronary vasodilators during ultrasound treatment that also have direct tissue-salvaging effects. Therapeutic ultrasound, therefore, has potential for treatment of acute and chronic myocardial ischemia independent of its effect on thrombolysis.

Effects of Non-thermal, Non-cavitational Ultrasound Exposure on Human Diabetic Ulcer Healing and Inflammatory Gene Expression in a Pilot Study

The purpose of this clinical study was to assess, in a limited patient population, the potential for a novel advanced wound care treatment based on low-frequency (20 kHz) low-intensity (spatial peak temporal peak intensity <100 mW/cm²; i.e., pressure amplitude of 55 kPa) ultrasound (LFLI-US), to affect wound closure rate in human diabetic foot ulcers (DFUs) and to effect changes in the relative expression of pro-inflammatory and anti-inflammatory genes. The ratio of expression of these genes, termed the M1/M2 score because it was inspired by the transition of macrophages from pro-inflammatory (M1) to anti-inflammatory (M2) phenotypes as wound healing progresses, was previously presented as a potential healing indicator for DFUs treated with the standard of care. We previously found that non-cavitational, non-thermal LFLI-US delivered with a pulse repetition frequency of 25 Hz was effective at improving wound healing in a pilot study of 20 patients with chronic venous ulcers. In this study, we assessed the potential for weekly LFLI-US exposures to affect wound healing in patients with diabetic ulcers, and we analyzed temporal changes in the M1/M2 score in debrided diabetic wound tissue. Although this was a limited patient population of only 8 patients, wounds treated with LFLI-US exhibited a significantly faster reduction in wound size compared with sham-treated patients (p < 0.001). In addition, the value of the M1/M2 score decreased for all healing diabetic ulcers and increased for all non-healing diabetic ulcers, suggesting that the M1/M2 score could be useful as an indicator of treatment efficacy for advanced DFU treatments. Such an indicator would facilitate clinical decision making, ensuring optimal wound management and thus contributing to reduction of health care expenses. Moreover, the results presented may contribute to an understanding of the mechanisms underlying ultrasonically assisted chronic wound healing. Knowledge of these mechanisms could lead to personalized or patient-tailored treatment.

Cortical Hemodynamic Responses Under Focused Ultrasound Stimulation Using Real-Time Laser Speckle Contrast Imaging

Although there is increasing use of focused ultrasound stimulation (FUS) in brain studies, the real-time changes of the cerebral blood flow (CBF) due to FUS remain unclear. In this study, we developed a novel scheme combining FUS and laser speckle contrast imaging, which can be used to measure the CBF caused by FUS in real time. The results showed that the change of CBF increased from 0 to 30 s and reached up to the maximum of 115.1 ± 6.5% at 30 s and then decreased gradually from 30 to 60 s. This study demonstrates that FUS was able to increase CBF and alter cortical hemodynamic responses, which indicates that FUS is a potential non-invasive method to study ischemic stroke rehabilitation.

Comparison of the effects of 1MHz and 3MHz therapeutic ultrasound on endothelium-dependent vasodilation of humans: a randomised clinical trial

OBJECTIVE

To compare the effects of different waveforms of 1MHz and 3MHz therapeutic ultrasound on endothelial function in healthy subjects.

DESIGN

Randomised placebo-controlled, crossover study with concealed allocation and assessor blinding.

SETTING

Imaging Centre of the University Hospital.

PARTICIPANTS

Thirty volunteers aged between 18 and 35 years were divided into two homogeneous groups (1MHz and 3MHz).

INTERVENTIONS

Continuous (CUT; 0.4W/cm^2SATA), pulsed (PUT; 20% duty cycle, 0.08W/cm^2SATA) and placebo waveforms (equipment off) of ultrasound (1MHz and 3MHz) were randomized and applied over the brachial artery for 5minutes.

MAIN OUTCOME MEASURES

Endothelial function was evaluated using the flow-mediated dilation (FMD) technique.

RESULTS

Both 1MHz [CUT: mean difference 4%, 95% confidence interval (CI) 2 to 6%, P<0.001; PUT: mean difference 4%, 95% CI 2 to 6%, P<0.001] and 3MHz (CUT: mean difference 4%, 95% CI 2 to 6%, P<0.001; PUT: mean difference 4%, 95% CI 2 to 6%, P<0.001) of therapeutic ultrasound increased %FMD by approximately 4% compared with the placebo waveforms. The endothelium-dependent vasodilator responses were the same for both types of waves and frequencies. No differences in baseline diameter, hyperaemic flow, and nitroglycerin-mediated diameter and vasodilation were observed between groups.

CONCLUSION

Both CUT and PUT ultrasound waveforms improved endothelial function. The 1MHz and 3MHz frequencies of therapeutic ultrasound led to similar improvement in endothelial function in healthy volunteers. Clinical trial registration number RBR-4z5z3t.

Therapeutic application of contrast ultrasound in ST elevation myocardial infarction: Role in coronary thrombosis and microvascular obstruction

In the past few decades, cardiac ultrasound has become a widely available, easy-to-use diagnostic tool in many scenarios in acute cardiac care. The introduction of microbubbles extended its diagnostic value. Not long thereafter, several investigators explored the therapeutic potential of contrast ultrasound on thrombus dissolution. Despite large improvements in therapeutic options, acute ST elevation myocardial infarction remains one of the main causes of mortality and morbidity in the western world. The therapeutic effect of contrast ultrasound on thrombus dissolution might prove to be a new, effective treatment strategy in this group of patients. With the recent publication of human studies scrutinising the therapeutic options of ultrasound and microbubbles in ST elevation myocardial infarction, we have entered a new stage in this area of research. This therapeutic effect is based on biochemical effects both at macrovascular and microvascular levels, of which the exact working mechanisms remain to be elucidated in full. This review will give an up-to-date summary of our current knowledge of the therapeutic effects of contrast ultrasound and its potential application in the field of ST elevation myocardial infarction, along with its future developments.

Low-Frequency Ultrasound Debridement in Chronic Wound Healing: A Systematic Review of Current Evidence

Chronic wounds are painful and debilitating to patients, pose a clinical challenge to physicians, and impose financial burden on the health-care system. New treatment options are therefore highly sought after. Ultrasound debridement is a promising technology that functions to disperse bacterial biofilms and stimulate wound healing. In this review, we focus on low-frequency ultrasound (20-60 kHz) and summarize the findings of 25 recent studies examining ultrasound efficacy. Ultrasound debridement appears to be most effective when used 3 times a week and has the potential to decrease exudate and slough, decrease patient pain, disperse biofilms, and increase healing in wounds of various etiology. Although current studies are generally of smaller size, the results are promising and we recommend the testing of low-frequency ultrasound therapy in clinical practice on a larger scale.

A Review on Brain Stimulation Using Low Intensity Focused Ultrasound

Brain stimulation techniques are important in both basic and clinical studies. Majority of well-known brain stimulating techniques have low spatial resolution or entail invasive processes. Low intensity focused ultrasound (LIFU) seems to be a proper candidate for dealing with such deficiencies. This review recapitulates studies which explored the effects of LIFU on brain structures and its function, in both research and clinical areas.

Although the mechanism of LIFU action is still unclear, its different effects from molecular level up to behavioral level can be explored in animal and human brain. It can also be coupled with brain imaging assessments in future research.

Towards use of MRI-guided ultrasound for treating cerebral vasospasm

Cerebral vasospasm is a major cause of morbidity and mortality in patients with subarachnoid hemorrhage (SAH), causing delayed neurological deficits in as many as one third of cases. Existing therapy targets induction of cerebral vasodilation through use of various drugs and mechanical means, with a range of observed efficacy. Here, we perform a literature review supporting our hypothesis that transcranially delivered ultrasound may have the ability to induce therapeutic cerebral vasodilation and, thus, may one day be used therapeutically in the context of SAH. Prior studies demonstrate that ultrasound can induce vasodilation in both normal and vasoconstricted blood vessels in peripheral tissues, leading to reduced ischemia and cell damage. Among the proposed mechanisms is alteration of several nitric oxide (NO) pathways, where NO is a known vasodilator. While in vivo studies do not point to a specific physical mechanism, results of in vitro studies favor cavitation induction by ultrasound, where the associated shear stresses likely induce NO production. Two papers discussed the effects of ultrasound on the cerebral vasculature. One study applied clinical transcranial Doppler ultrasound to a rodent complete middle cerebral artery occlusion model and found reduced infarct size. A second involved the application of pulsed ultrasound in vitro to murine brain endothelial cells and showed production of a variety of vasodilatory chemicals, including by-products of arachidonic acid metabolism. In sum, nine reviewed studies demonstrated evidence of either cerebrovascular dilation or elaboration of vasodilatory compounds. Of particular interest, all of the reviewed studies used ultrasound capable of transcranial application: pulsed ultrasound, with carrier frequencies ranging between 0.5 and 2.0 MHz, and intensities not substantially above FDA-approved intensity values. We close by discussing potential specific treatment paradigms of SAH and other cerebral ischemic disorders based on MRI-guided transcranial ultrasound.

Effects of Different Therapeutic Ultrasound Waveforms on Endothelial Function in Healthy Volunteers: A Randomized Clinical Trial

The purpose of this study was to determine the effects of different therapeutic 1-MHz ultrasound waveforms on endothelial function before and after cyclooxygenase (COX) inhibition. Forty-two healthy volunteers aged 27.2 ± 3.8 y underwent interventions and an evaluation for endothelial function (n = 15; with COX inhibition, n = 15; duration of the vasodilator effect, n = 12) by technique flow-mediated dilation. Continuous ultrasound therapy (0.4 W/cm(2 SATA)), pulsed ultrasound therapy (20% duty cycle, 0.08 W/cm(2 SATA)) or placebo (equipment power off) was randomly applied over the brachial artery for 5 min. COX inhibition (aspirin) was carried out 30 min before treatments. In relation to the placebo, flow-mediated dilation increased by 4.8% using continuous ultrasound and by 3.4% using pulsed ultrasound. After COX, flow-mediated dilation was enhanced by 2.1% by continuous ultrasound and 2.6% by pulsed ultrasound. This vasodilation persisted for 20 min. Continuous and pulsed therapeutic 1-MHz ultrasound waveforms improved endothelial function in humans, which provided them with anti-inflammatory vascular effects.

The correlation between admission blood glucose and intravenous rt-PA-induced arterial recanalization in acute ischemic stroke: a multi-centre TCD study

BACKGROUND

The relationship between hyperglycemia and arterial recanalization following intravenous recombinant tissue-plasminogen activator treatment in acute ischemic stroke is not well understood.

AIM

We aimed to evaluate the effects of hyperglycemia in thrombolysed ischemic stroke patients on recanalization rate and clinical outcome.

METHODS

We studied 348 (231 subjects from the CLOTBUST databank and 117 subjects from the CLOTBUST trial phase II) with documented intracranial artery occlusion treated with intravenous recombinant tissue-plasminogen activator. Serum glucose was determined at baseline before intravenous recombinant tissue-plasminogen activator administration. Hyperglycemia was defined as a glucose level ≥140 mg/dl (7·7 mmol/l). Transcranial Doppler findings were interpreted using the thrombolysis in brain ischemia flow grading system as persistent arterial occlusion, re-occlusion or complete recanalization. Poor clinical outcome was defined by modified Rankin score > 2 at three-months.

RESULTS

At baseline, 138 patients (37·4%) were hyperglycemic and 210 patients (56·9%) normoglycemic. Baseline characteristics based on glucose ≥ 140 (7·7 mmol/l) or less 140: age (70·0 ± 12·4 vs. 67·3 ± 14·1, P = 0·065), baseline National Institutes of Health Stroke Scale (17·0 ± 5·5 vs. 15·8 ± 5·5, P = 0·054), time to recombinant tissue-plasminogen activator (141·4 ± 69·1 vs. 145·3 ± 48·4 mins, P = 0·56), and history of diabetes mellitus [60/138 (43·5%) vs. 22/210 (10·5%), P < 0·001]). Patients with hyperglycemia have a higher rate of persisting occlusion [72/138 (52·2%) vs. 66/210 (31·4%)] and less rate of complete recanalization [34/138 (24·6%) vs. 82/210 (39%), P < 0·001]. Median time to recanalization in patients with severe hyperglycemia (glucose ≥ 200) (11 mmol/l) and glucose <200 was 163 ± 79 and 131 ± 90 mins, respectively (P = 0·045). Sixteen patients (11·6%) in the hyperglycemic group and 12 (5·7%) in the normoglycemic group had symptomatic intracerebral hemorrhage (P = 0·049). Seventy-eight patients (69%) in the hyperglycemia group and 72 patients (41·6%) in the normoglycemic group had poor clinical outcome (three-month modified Rankin score > 2) (P ≤ 0·001). After adjusting for stroke risk factors, patients with hyperglycemia were more likely to have poor clinical outcome (three-month modified Rankin score > 2) (adjusted odds ratio = 2·22, 95% confidence interval: 1·2-4·11, P = 0·011) and low complete recanalization rate (adjusted odds ratio: 0·5, confidence interval: 0·3-0·92, P = 0·025) with trend of increase risk of symptomatic intracerebral hemorrhage (adjusted odds ratio: 2·07, confidence interval:0·8-5·1, P = 0·114). There was no association between baseline glucose as a continuous variable and poor clinical outcome, but there was with the complete recanalization's rate.

CONCLUSION

Hyperglycemia is associated with low rate of complete recanalization and poor clinical outcome in intravenous recombinant tissue-plasminogen activator-treated patients. Further studies are needed to evaluate whether lowering hyperglycemia is beneficial in the management of acute stroke patients.

Augmentation of limb perfusion and reversal of tissue ischemia produced by ultrasound-mediated microbubble cavitation

BACKGROUND

Ultrasound can increase tissue blood flow, in part, through the intravascular shear produced by oscillatory pressure fluctuations. We hypothesized that ultrasound-mediated increases in perfusion can be augmented by microbubble contrast agents that undergo ultrasound-mediated cavitation and sought to characterize the biological mediators.

METHODS AND RESULTS

Contrast ultrasound perfusion imaging of hindlimb skeletal muscle and femoral artery diameter measurement were performed in nonischemic mice after unilateral 10-minute exposure to intermittent ultrasound alone (mechanical index, 0.6 or 1.3) or ultrasound with lipid microbubbles (2×10(8) IV). Studies were also performed after inhibiting shear- or pressure-dependent vasodilator pathways, and in mice with hindlimb ischemia. Ultrasound alone produced a 2-fold increase (P<0.05) in muscle perfusion regardless of ultrasound power. Ultrasound-mediated augmentation in flow was greater with microbubbles (3- and 10-fold higher than control for mechanical index 0.6 and 1.3, respectively; P<0.05), as was femoral artery dilation. Inhibition of endothelial nitric oxide synthase attenuated flow augmentation produced by ultrasound and microbubbles by 70% (P<0.01), whereas inhibition of adenosine-A2a receptors and epoxyeicosatrienoic acids had minimal effect. Limb nitric oxide production and muscle phospho-endothelial nitric oxide synthase increased in a stepwise fashion by ultrasound and ultrasound with microbubbles. In mice with unilateral hindlimb ischemia (40%-50% reduction in flow), ultrasound (mechanical index, 1.3) with microbubbles increased perfusion by 2-fold to a degree that was greater than the control nonischemic limb.

CONCLUSIONS

Increases in muscle blood flow during high-power ultrasound are markedly amplified by the intravascular presence of microbubbles and can reverse tissue ischemia. These effects are most likely mediated by cavitation-related increases in shear and activation of endothelial nitric oxide synthase.

Ultrasound stimulates formation and release of vasoactive compounds in brain endothelial cells

Stroke outcome is improved by therapeutic ultrasound. This benefit is presumed to be principally from ultrasound-mediated thrombolysis. We hypothesized that the therapeutic benefit of ultrasound in stroke may, in part, be mediated by the release of beneficial vasoactive substances. Accordingly, we investigated the effect of ultrasound on levels of cytochrome P-450, lipoxygenase, and cyclooxygenase metabolites of arachidonic acid as well as adenosine release and endothelial nitric oxide synthase (eNOS) phosphorylation in primary brain endothelial cells in vitro. Brain endothelial cells were exposed to 1.05-MHz ultrasound at peak rarefactional acoustic pressure amplitudes of 0.35, 0.55, 0.90, and 1.30 MPa. Epoxyeicosatrienoic acids (EETs), hydroxyeicosatetraenoic acids (HETEs), PGE2, adenosine, nitrate/nitrite, and eNOS phosphorylation were measured after ultrasound exposure. Levels of 8,9-EET, 11,12-EET, and 14,15-EET increased by 230 ± 28%, 240 ± 30%, and 246 ± 31% (P < 0.05), respectively, whereas 5-HETE and 15-HETE levels were reduced to 24 ± 14% and 10 ± 3% (P < 0.05), respectively, compared with cells not exposed to ultrasound. PGE2 levels were reduced to 56 ± 14% of control. Adenosine increased more than sixfold after ultrasound exposure compared with unstimulated cells (1.36 ± 0.22 vs. 0.37 ± 0.10 ng/ml, P < 0.05), nitrate/nitrite was below levels of quantification, and eNOS phosphorylation was not altered significantly. Our results suggest that ultrasound may enhance tissue perfusion during stroke by augmenting the generation of vasodilator compounds and inhibiting that of vasoconstrictors. Such regulation supports a beneficial role for therapeutic ultrasound in stroke independent of its effect on the occlusive thrombus.

Pulsed Transcranial Ultrasound Stimulation Immediately After The Ischemic Brain Injury is Neuroprotective

GOAL

We applied a low-intensity pulsed transcranial ultrasound stimulation (pTUS) to the ischemic cortex after a distal middle cerebral artery occlusion (dMCAO) to study whether pTUS is capable of protecting brain from ischemic injury.

METHODS

Rats were randomly assigned to Sham (n = 6), Control (n = 16), and pTUS (n = 16) groups. The pTUS-treated rats were subjected to 60-min ultrasonic stimulation immediately after the ischemia. After 48 h, the sensorimotor-related behavioral outcomes were assessed by a neurological severity score (NSS), and the permanent brain injury was assessed by the histologic analysis of TTC staining of brain slices.

RESULTS

pTUS group showed significantly lower NSS (n = 10, 5.5 ± 2.5) than the Control group ( n = 10, 10.5 ±1.4) (p < 0.01). Concordantly, the ischemic lesion was significantly reduced after receiving pTUS immediately after dMCAO. The cortical infarct volume in the control group was more than threefold of the pTUS group (43.39% ± 2.33%, n = 16 versus 13.78% ± 8.18%, n = 16, p < 0.01). Immunohistochemical staining indicated reduction of neutrophils in the affected area, and laser speckle imaging showed significant increase of a cerebral blood flow after pTUS, which consistently supported the neuroprotection of pTUS in ischemic brain injury.

CONCLUSION

Both behavior and histological results suggested that pTUS on ischemic core immediately after ischemic stroke could be neuroprotective.

SIGNIFICANCE

The noninvasiveness and high spatiotemporal resolution of pTUS makes it a unique neuromodulation technique in comparison with the current TMS and tDCS.

External ultrasound for carotid atherosclerotic plaque treatment

OBJECTIVES

The purpose of this study was to evaluate the efficacy of external ultrasound in the treatment of carotid atherosclerotic plaques.

METHODS

In the prospective study, 357 patients with 363 carotid atherosclerotic plaques were divided into an ultrasound treatment group and a control group. For 30 days, conventional medical treatment was conducted on 54 plaques in the control group, whereas irradiation therapy in addition to conventional medical treatment was conducted on 309 plaques in the ultrasound group. Carotid sonography was conducted before and after treatment, and the maximum plaque thickness and area were measured in a longitudinal section.

RESULTS

No patients withdrew from the treatment because of related side effects. After treatment, the maximum thickness and area of 79.94% of the plaques in the ultrasound group were reduced, whereas in the control group, the thickness and area of 18.52% were reduced. The mean changes in plaque thickness and area ± SD in the ultrasound and control groups were 0.22 ± 0.19 mm (7.61% ± 5.67%) versus 0.02 ± 0.05 mm (0.74% ± 1.64%) and 0.047 ± 0.039 cm(2) (13.28% ± 9.8%) versus 0.0044 ± 0.0102 cm(2) (1.1% ± 2.46%), respectively. Changes in both plaque thickness and area in the ultrasound group were significantly greater than those in the control group (P< .0001). Furthermore, the plaque echo type was another prognostic factor affecting efficacy (P < .05).

CONCLUSIONS

External ultrasound treatment is safe and effective for carotid atherosclerotic plaques and is worthy of further research and applications. The efficacy in anechoic/hypoechoic plaques is significantly higher than that in mixed echoic and calcified echoic plaques.

Acoustic droplet-hydrogel composites for spatial and temporal control of growth factor delivery and scaffold stiffness

Wound healing is regulated by temporally and spatially restricted patterns of growth factor signaling, but there are few delivery vehicles capable of the "on-demand" release necessary for recapitulating these patterns. Recently we described a perfluorocarbon double emulsion that selectively releases a protein payload upon exposure to ultrasound through a process known as acoustic droplet vaporization (ADV). In this study, we describe a delivery system composed of fibrin hydrogels doped with growth factor-loaded double emulsion for applications in tissue regeneration. Release of immunoreactive basic fibroblast growth factor (bFGF) from the composites increased up to 5-fold following ADV and delayed release was achieved by delaying exposure to ultrasound. Releasates of ultrasound-treated materials significantly increased the proliferation of endothelial cells compared to sham controls, indicating that the released bFGF was bioactive. ADV also triggered changes in the ultrastructure and mechanical properties of the fibrin as bubble formation and consolidation of the fibrin in ultrasound-treated composites were accompanied by up to a 22-fold increase in shear stiffness. ADV did not reduce the viability of cells suspended in composite scaffolds. These results demonstrate that an acoustic droplet-hydrogel composite could have broad utility in promoting wound healing through on-demand control of growth factor release and/or scaffold architecture.

Prenatal ultrasound exposure and association with postnatal hearing outcomes

Objective

Prenatal ultrasound exams have become increasingly frequent. Although no serious adverse effects are known, the public health implications would be enormous should adverse effects on auditory development be shown. This study looks to establish a possible correlation between hearing loss and increased prenatal ultrasound exposure.

Design

Retrospective cohort analysis.

Setting

Tertiary academic referral center.

Methods

A retrospective review of 100 children undergoing newborn hearing screening was conducted. Extensive data collection was performed, and this data was analyzed for a potential correlation between failure of newborn hearing screening and increased prenatal ultrasound exposure, as well as for a potential correlation of other variables with hearing loss.

Main outcome measures

Postnatal hearing outcomes.

Results

A higher number of both total and 3^rd trimester ultrasound exams as well as a younger gestational age at birth were all found to be significantly associated with a higher likelihood of passing the newborn hearing screen (p<0.001 for each). No other factors were found to reach statistical significance.

Conclusions

Our results show that there is no correlation between a higher level of prenatal ultrasound exposure and hearing loss. Indeed, infants who had more prenatal ultrasounds in the third trimester were more likely to pass their screening hearing exams. The finding that children receiving more prenatal ultrasounds have a higher likelihood of passing newborn hearing screens serves as an excellent reminder of the classic statistics rule that correlation does not imply causation.

Focused ultrasound delivers targeted immune cells to metastatic brain tumors

Natural killer (NK) cells are cytotoxic lymphocytes involved in innate immunity. NK-92, a human NK cell line, may be targeted to tumor-associated antigens in solid malignancies where it exhibits antitumor efficacy, but its clinical utility for treating brain tumors is limited by an inability to cross the blood-brain barrier (BBB). We investigated the potential for focused ultrasound (FUS) to deliver targeted NK-92 cells to the brain using a model of metastatic breast cancer. HER2-expressing human breast tumor cells were implanted into the brain of nude rats. The NK-92-scFv(FRP5)-zeta cell line expressing a chimeric HER2 antigen receptor was transfected with superparamagnetic iron oxide nanoparticles before intravenous injection, before and following BBB disruption using focused ultrasound (551.5 kHz focused transducer, 0.33 MPa average peak rarefaction pressure) in the presence of a microbubble contrast agent. Baseline and posttreatment 1.5T and 7T MR imaging was done, and histology used to identify NK-92 cells post-mortem. Contrast-enhanced MRI showed reproducible and consistent BBB disruption. 7T MR images obtained at 16 hours posttreatment revealed a significant reduction in signal indicating the presence of iron-loaded NK-92 cells at the tumor site. The average ratio of NK-92 to tumor cells was 1:100 when NK cells were present in the vasculature at the time of sonication, versus 2:1,000 and 1:1,000 when delivered after sonication and without BBB disruption, respectively. Our results offer a preclinical proof-of-concept that FUS can improve the targeting of immune cell therapy of brain metastases.

Ultrasound stimulation restores impaired neovascularization-related capacities of human circulating angiogenic cells

AIMS

Unsatisfactory effects of therapeutic angiogenesis in critical limb ischaemia may be ascribed to use of circulating angiogenic cells (CACs) derived from atherosclerotic patients with impaired neovascularization-related capacities. We tested whether ultrasound cell stimulation can restore the impaired capacities.

METHODS AND RESULTS

During culture of human peripheral blood-derived mononuclear cells for 4 days to achieve CACs, we stimulated the cells in culture daily with low-intensity pulsed ultrasound stimulation (LIPUS). Application of LIPUS to cells in culture derived from healthy volunteers augmented the generation and migration capacities of CACs, increased concentrations of angiopoietin 2 and nitrogen oxides in the culture medium, and increased the expression of phosphorylated-Akt and endothelial nitric oxide synthase in CACs on western blotting. Application of LIPUS to cells in culture derived from atherosclerotic patients also augmented the generation and migration capacities of CACs. Although neovascularization in the ischaemic hindlimb of athymic nude mice was impaired after intramuscular injection of CACs derived from atherosclerotic patients compared with that using CACs derived from healthy volunteers, LIPUS of the cells in culture derived from atherosclerotic patients restored the neovascularization capacities.

CONCLUSION

Therapeutic angiogenesis with LIPUS-pre-treated CACs may be a new strategy to rescue critical limb ischaemia in atherosclerotic patients.

Therapeutic modalities--an updated review for the hand surgeon

The number of therapeutic modalities available to the hand surgeon has greatly increased over the past several decades. A field once predicated only on heat, massage, and cold therapy now uses electrical stimulators, ultrasound, biofeedback, iontophoresis, phonophoresis, mirror therapy, lasers, and a number of other modalities. With this expansion in choices, there has been a concurrent effort to better define which modalities are truly effective. In this review, we aim to characterize the commonly used modalities and provide the evidence available that supports their continued use.

A review of low-intensity focused ultrasound pulsation

With the recent approval by the Food and Drug Administration (FDA) of Deep Brain Stimulation (DBS) for Parkinson's Disease, dystonia and obsessive compulsive disorder (OCD), vagus nerve stimulation (VNS) for epilepsy and depression, and repetitive transcranial magnetic stimulation (rTMS) for the treatment of depression, neuromodulation has become increasingly relevant to clinical research. However, these techniques have significant drawbacks (eg, lack of special specificity and depth for the rTMS, and invasiveness and cumbersome maintenance for DBS). This article reviews the background, rationale, and pilot studies to date, using a new brain stimulation method-low-intensity focused ultrasound pulsation (LIFUP). The ability of ultrasound to be focused noninvasively through the skull anywhere within the brain, together with concurrent imaging (ie, functional magnetic resonance imaging [fMRI]) techniques, may create a role for research and clinical use of LIFUP. This technique is still in preclinical testing and needs to be assessed thoroughly before being advanced to clinical trials. In this study, we review over 50 years of research data on the use of focused ultrasound (FUS) in neuronal tissue and live brain, and propose novel applications of this noninvasive neuromodulation method.

Potential use of ultrasound to promote protein crystallization

This work shows promising applications of ultrasound in promoting protein crystallization, which is important for structure determination by X-ray crystallography. It was observed that ultrasound can be used as a nucleation promoter as it decreases the energy barrier for crystal formation. Crystallization experiments on egg-white lysozyme were carried out with and without ultrasonic irradiation using commercial crystallization plates placed in temperature-controlled water baths. The nucleation-promoting effect introduced by ultrasound is illustrated by the reduction of the metastable zone width, as measured by the isothermal microbatch technique. The same effect was confirmed by the increased number of conditions leading to the formation of crystals when vapour diffusion techniques were carried out in the presence of ultrasound. By inducing faster nucleation, ultrasound leads to protein crystals grown at low supersaturation levels, which are known to have better diffraction properties. In fact, X-ray diffraction data sets collected using 13 lysozyme crystals (seven grown with ultrasound and six without) show an average 0.1 Å improvement in the resolution limit when ultrasound was used (p< 0.10). Besides the immediate application of ultrasound in nucleation promotion, the preliminary diffraction results also suggest a promising application in crystal quality enhancement.

Potential teratogenic effects of ultrasound on corticogenesis: implications for autism

The phenotypic expression of autism, according to the Triple Hit Hypothesis, is determined by three factors: a developmental time window of vulnerability, genetic susceptibility, and environmental stressors. In utero exposure to thalidomide, valproic acid, and maternal infections are examples of some of the teratogenic agents which increase the risk of developing autism and define a time window of vulnerability. An additional stressor to genetically susceptible individuals during this time window of vulnerability may be prenatal ultrasound. Ultrasound enhances the genesis and differentiation of progenitor cells by activating the nitric oxide (NO) pathway and related neurotrophins. The effects of this pathway activation, however, are determined by the stage of development of the target cells, local concentrations of NO, and the position of nuclei (basal versus apical), causing consequent proliferation at some stages while driving differentiation and migration at others. Ill-timed activation or overactivation of this pathway by ultrasound may extend proliferation, increasing total cell number, and/or may trigger precipitous migration, causing maldistribution of neurons amongst cortical lamina, ganglia, white matter, and germinal zones. The rising rates of autism coincident with the increased use of ultrasound in obstetrics and its teratogenic/toxic effects on the CNS demand further research regarding a putative correlation.

Cellular Alterations in Cultured Endothelial Cells Exposed to Therapeutic Ultrasound Irradiation

Restoration of blood supply to tissue with impaired perfusion depends on spontaneous or mediated angiogenesis, which among other mechanisms includes stimulation, migration, and proliferation of endothelial cells (ECs). Therapeutic ultrasound (US) irradiation is known as an inducer of cellular modifications and is used to accelerate wound healing. An in vitro setup was developed in order to allow for a comprehensive investigation of cellular alterations induced in cultured ECs after exposure to different modes of therapeutic US irradiation. Viability assays revealed a higher rate of proliferation in the sonicated groups, although cell death was not observed. Visualization of actin stress fibers demonstrated partial disassembly of the fibers immediately after US sonication, with a maximum after about 2 h. However, 24 h following sonication the fibers regain normal appearance. A similar behavior was observed with the microtubules and focal adhesion complexes. Utilizing a wound healing assay revealed that migration rate of ECs is enhanced by US irradiation. These findings hint that therapeutic US sonication of ECs results in temporarily cellular alterations, which may induce tissue remodeling via stimulation of EC proliferation and migration.

Shock waves in the treatment of stress fractures

In soccer players, lower extremity stress fractures are common injuries and are the result of repetitive use damage that exceeds the intrinsic ability of the bone to repair itself. They may be treated conservatively but this may cause long-term complications, such as delayed union, muscle atrophy and chronic pain. Stress fractures that fail to respond to this management require surgical treatment, which is also not without risks and complications. Extracorporeal shock wave therapy (ESWT) has been used successfully on fracture complications, such as delayed union and nonunion. As such, we want to examine ESWT in the management of stress fractures. In this article, we present a retrospective study of 10 athletes affected by chronic stress fractures of the fifth metatarsus and tibia that received three to four sessions of low-middle energy ESWT. At the follow-up (8 wk on average), the clinical and radiography results were excellent and enabled all players to gradually return to sports activities. These reports show that ESWT is a noninvasive and effective treatment for resistant stress fractures in soccer players.