Contractions Induced in Human Pulmonary Arteries by a H2S Donor, GYY 4137, Are Inhibited by Low-Frequency (20 kHz) Ultrasound.

The present study aimed to investigate the effect of a H2S donor, GYY 4137, on human pulmonary arteries and whether low-frequency ultrasound (20 kHz, 4 W/cm2) inhibits GYY 4137 contractions. Functional studies were conducted on human and rat pulmonary arteries mounted on microvascular myographs. We placed an ultrasonic gadget in the tissue organ bath to insonate the arteries with low-frequency ultrasound. To measure the effect of the low-frequency ultrasound on the entrance of extracellular Ca2+, the preparations were placed in a Ca2+-free solution, and the thromboxane agonist, U46619, and extracellular calcium were added in the presence of insonation. In isolated human pulmonary arteries, GYY 4137 induced contractions, which were most pronounced in the arteries contracted with the thromboxane analogue, U46619. The transient GYY4137 contractions were reversed by low-frequency ultrasound, a blocker of KV7 channels, XE-991 (10 µM), and glibenclamide (1 µM), a blocker of ATP-sensitive channels. Low-frequency ultrasound also inhibited the contractions induced by the smooth muscle entrance of increasing extracellular calcium concentrations. The present findings show that GYY 4137 can cause a transient contraction of pulmonary arteries in human arteries. GYY 4137 alone does not cause significant vascular contraction in rat lung arteries, but it contracts rat lung arteries precontracted with U46619. The transient contractions induced by GYY 4137 can be inhibited by low-frequency ultrasound, probably by counteracting the influx of external Ca2+. The effect of low-frequency ultrasound counteracts contraction in pulmonary arteries; therefore, a possibility could be to develop a larger device allowing treatment of patients with pulmonary hypertension.

Evaluation of renal cortical echogenicity in healthy cats using anisotropic backscatter artifacts and echogenicity differences among internal organs.

BACKGROUND: Renal cortical anisotropic backscatter artifact (CABA) is a hyperechoic region of the renal poles where the insonation of sound beams is perpendicular to the renal tubules within the renal cortex. AIMS: To determine whether renal CABA can be observed in healthy cats and to compare the echogenicity of renal CABA with that of the spleen and liver. MATERIAL AND METHODS: Images of the spleen, liver, kidneys, and urinary bladder were acquired from 30 clinically healthy cats with renal CABA. Echogenicity differences among organs and echo scores within urine were recorded and analyzed. All ultrasound images were acquired using a 7.2-14-MHz linear transducer. Univariate logistic regression was used to assess the associations between the presence of renal CABA and various variables. RESULTS: The prevalence of the renal CABA was 86.7% (26/30) and 93.3% (28/30) according to different observers. The reproducibility of renal CABA is substantial to excellent. The renal CABA echogenicity was greater or equal to the spleen and greater than the hepatic echogenicity in 90.0% of cats (27/30). For comparison with the spleen and liver, there were three and six combinations of echogenicity differences using the CABA and non-CABA regions, respectively. The renal cortical echogenicity in the CABA region was higher than the liver in all subjects. Renal CABA was not associated with age, body weight, gender, body condition score, or lipid droplets in the urinary bladder. CONCLUSION: Renal CABA was present in most healthy cats and could be used for echogenicity comparisons with the liver and spleen.

Nanodroplet-Mediated Low-Energy Mechanical Ultrasound Surgery.

Mechanical ultrasound surgery methods use short, high-intensity pulses to fractionate tissues. This study reports the development of a two-step technology for low-energy mechanical ultrasound surgery of tissues using nanodroplets to reduce the pressure threshold. Step 1 consists of vaporizing the nanodroplets into gaseous microbubbles via megahertz ultrasound excitation. Then, low-frequency ultrasound is applied to the microbubbles, which turns them into therapeutic warheads that trigger potent mechanical effects in the surrounding tissue. The use of nanoscale nanodroplets coupled with low-frequency ultrasound reduces the pressure threshold required for mechanical ultrasound surgery by an order of magnitude. In addition, their average diameter of 300 nm can overcome challenges associated with the size of microbubbles. Optimization experiments were performed to determine the ultrasound parameters for nanodroplet vaporization and the subsequent microbubble implosion processes. Optimal vaporization was obtained when transmitting a 2-cycle excitation pulse at a center frequency of 5 MHz and a peak negative pressure of 4.1 MPa (mechanical index = 1.8). Low-frequency insonation of the generated microbubbles at a center frequency of 850, 250 or 80 kHz caused enhanced contrast reduction at a center frequency of 80 kHz, compared with the other frequencies, while operating at the same mechanical index of 0.9. Nanodroplet-mediated insonation of ex vivo chicken liver samples generated mechanical damage. Low-frequency treatment at a mechanical index of 0.9 and a center frequency of 80 kHz induced the largest lesion area (average of 0.59 mm2) compared with 250- and 850-kHz treatments with the same mechanical index (average lesions areas of 0.29 and 0.19 mm2, respectively, p < 0.001). The two-step approach makes it possible to conduct both the vaporization and implosion stages at mechanical indices below 1.9, thus avoiding undesired mechanical damage. The findings indicate that coupled with low-frequency ultrasound, nanodroplets can be used for low-energy mechanical ultrasound surgery.

Sonoporation of Human Renal Proximal Tubular Epithelial Cells In Vitro to Enhance the Liberation of Intracellular miRNA Biomarkers.

Ultrasound has previously been demonstrated to non-invasively cause tissue disruption. Small animal studies have demonstrated that this effect can be enhanced by contrast microbubbles and has the potential to be clinically beneficial in techniques such as targeted drug delivery or enhancing liquid biopsies when a physical biopsy may be inappropriate. Cavitating microbubbles in close proximity to cells increases membrane permeability, allowing small intracellular molecules to leak into the extracellular space. This study sought to establish whether cavitating microbubbles could liberate cell-specific miRNAs, augmenting biomarker detection for non-invasive liquid biopsies. Insonating human polarized renal proximal tubular epithelial cells (RPTECs), in the presence of SonoVue microbubbles, revealed that cellular health could be maintained while achieving the release of miRNAs, miR-21, miR-30e, miR-192 and miR-194 (respectively, 10.9-fold, 7.17-fold, 5.95-fold and 5.36-fold). To examine the mechanism of release, RPTECs expressing enhanced green fluorescent protein were generated and the protein successfully liberated. Cell polarization, cellular phenotype and cell viability after sonoporation were measured by a number of techniques. Ultrastructural studies using electron microscopy showed gap-junction disruption and pore formation on cellular surfaces. These studies revealed that cell-specific miRNAs can be non-specifically liberated from RPTECs by sonoporation without a significant decrease in cell viability.

Low-Frequency (20 kHz) Ultrasonic Modulation of Drug Action.

We tested the effect of low-frequency ultrasound (LUS, 20 kHz, 4 W/cm2) on the function of rat mesentery and human pulmonary arteries with wire myography. The vessels were induced to contract with either noradrenaline or physiologic saline solution (PSS) with a high potassium concentration (KPSS) and then incubated with capsaicin (2.1 × 10-7 M, TRPV1 [transient receptor potential vanilloid 1] activator), dopamine (1 × 10-4 M, dopamine and α2-receptor activator), or fenoldopam (dopamineA1 receptor agonist, 1 × 10-4 M) with and without glibenclamide (1 µM, KATP [adenosine triphosphate {sensitive potassium channel (ATP)}-sensitive potassium channel] inhibitor and α2-receptor modulator), and insonated. Vessels were incubated in Ca2+-free PSS and induced to contract with added extracellular Ca2+ and noradrenaline. Pulmonary arteries were induced to contract with KPSS and dopamine. Then the vessels were insonated. LUS inhibited the influx of external Ca2+, inhibited the dopamine-induced vasoconstriction in the KPSS (glibenclamide reversible), reduced the capsaicin-induced vasorelaxation, increased the gentamicin-induced vasorelaxation and increased the dopamine-induced contraction in the KPSS in human pulmonary arteries.

Fetal Speckle-Tracking: Impact of Angle of Insonation and Frame Rate on Global Longitudinal Strain.

BACKGROUND: There is a growing body of research on fetal speckle-tracking echocardiography because it is considered to be an angle-independent modality. The primary aim of this study was to investigate whether angle of insonation and acquisition frame rate (FR) influence left ventricular endocardial global longitudinal peak strain (GLS) in the fetus. METHODS: Four-chamber views of 122 healthy fetuses were studied at three different angles of insonation (apex up/down, apex oblique, and apex perpendicular) at high and low acoustic FRs. GLS was calculated, and a linear mixed-model analysis was used for analysis. Six hundred fifty-six fetal echocardiographic clips were analyzed (288 in the second trimester, at a median gestation of 21 weeks [interquartile range (IQR), 1 week], and 368 in the third trimester, at a median gestation of 36 weeks [IQR, 2 weeks]). RESULTS: Angle of insonation and FRs were significant determinants of GLS. Ventricular septum perpendicular to the ultrasound beam was associated with higher (more negative) GLS compared with apex up/down (at high FR: -21.8% vs -19.7%, P < .001; at low FR: -24.1% vs -21.4%, P < .001). Higher frames per second (FPS; median 149 FPS [IQR, 33 FPS] = 61 frames per cycle [FPC] [IQR, 17 FPC]) compared with lower FPS (median 51 FPS [IQR, 15 FPS] = 22 FPC [IQR, 7 FPC]) at the same insonation angle resulted in lower GLS (apex up/down: -19.7% vs -21.4%, P < .001; apex oblique: -21.2% vs -22.7%, P < .001; apex perpendicular: -21.8% vs -24.1%, P < .001). CONCLUSIONS: The present findings show that insonation angle and FR influence GLS significantly. These factors need to be considered when comparing studies with different acquisition protocols, when establishing normative values, and when interpreting pathology. Speckle-tracking echocardiography cannot be considered an angle-independent modality during fetal life.

Local anesthesia enhanced with increasing high-frequency ultrasound intensity.

The effect of local anesthetics, particularly those which are hydrophilic, such as tetrodotoxin, is impeded by tissue barriers that restrict access to individual nerve cells. Methods of enhancing penetration of tetrodotoxin into nerve include co-administration with chemical permeation enhancers, nanoencapsulation, and insonation with very low acoustic intensity ultrasound and microbubbles. In this study, we examined the effect of acoustic intensity on nerve block by tetrodotoxin and compared it to the effect on nerve block by bupivacaine, a more hydrophobic local anesthetic. Anesthetics were applied in peripheral nerve blockade in adult Sprague-Dawley rats. Insonation with 1-MHz ultrasound at acoustic intensity greater than 0.5 W/cm2 improved nerve block effectiveness, increased nerve block reliability, and prolonged both sensory and motor nerve blockade mediated by the hydrophilic ultra-potent local anesthetic, tetrodotoxin. These effects were not enhanced by microbubbles. There was minimal or no tissue injury from ultrasound treatment. Insonation did not enhance nerve block from bupivacaine. Using an in vivo model system of local anesthetic delivery, we studied the effect of acoustic intensity on insonation-mediated drug delivery of local anesthetics to the peripheral nerve. We found that insonation alone (at intensities greater than 0.5 W/cm2) enhanced nerve blockade mediated by the hydrophilic ultra-potent local anesthetic, tetrodotoxin. Graphical abstract.

El ultrasonido, de la cabecera del paciente al aula / Ultrasound, from the Patient's Bedside to the Classroom

Resumen: En los últimos años la ecografía a la cabecera del paciente ha crecido exponencialmente. Su aplicación es observada en el quirófano, en las unidades de cuidados intensivos, en urgencias, en la atención de primer nivel e incluso en el trabajo de campo. Es tan versátil que facilita el diagnóstico, mejora la monitorización de los pacientes y apoya en los procedimientos invasivos, todo esto de forma segura y eficaz. En el área de la educación médica ha permeado hasta el pregrado, donde ya se le propone como una herramienta didáctica que permite la vinculación entre el conocimiento de las ciencias básicas y la aplicación clínica. La ecografía corresponde a uno de los instrumentos más versátiles en la medicina contemporánea, por lo que se hace obligada y prioritaria una mayor capacitación e investigación en el tema.

Abstract: In recent years, ultrasound at the patient's bedside has exponentially grown. Its application has been observed in the operating room, intensive care units, emergency rooms, first-level care and even in field work. It is so versatile that it facilitates diagnosis, improves patient monitoring and supports invasive procedures, all in a safe and effective manner. It has been used as a didactic tool in medical education that helps create a link between basic sciences and clinical application. Ultrasound is one of the most versatile instruments in contemporary medicine, hence, more training and research in the subject is a must and a priority.

Effect of insonation angle on peak systolic velocity variation.

OBJECTIVES: As point of care ultrasound (POCUS) has become more integrated into emergency and critical care medicine, there has been increased interest in utilizing ultrasound to assess volume status. However, recent studies of carotid POCUS on volume status and fluid responsiveness fail to recognize the effect insonation angle has on their results. To address this, we studied the effect of insonation angle on peak systolic velocity (PSV) change associated with respiratory variation (RV) and passive leg raise (PLR). METHODS: Doppler measurements were obtained from 51 subjects presenting to the ED. Minimal and maximal PSV were obtained using insonation angles of 46°, 60°, and 90°. ∆PSV was calculated using PLR and RV as trial methods. Results were categorized into two groups, those with a ∆PSV > 10% and those with a ∆PSV ≤ 10%. ∆PSV mean and standard error, as well as measures of agreement were calculated. RESULTS: Mean ∆PSV associated with PLR test was 9% in the 46° and 60° groups, and 18% in the 90° group, with standard errors of 6, 7, and 14%, respectively. Using 46° as our relative gold standard, Kappa was 0.23 at 60° and 0.11 at 90° with RV as the trial method, and 0.23 at 60° and 0.01 at 90° with a PLR as the trial method. CONCLUSIONS: Variation in PSV is heavily dependent on insonation angle. There was only slight to fair agreement in ∆PSV among the various insonation angles. Further investigation of the optimal insonation angle to assess ∆PSV should be undertaken.

Changes in the microvasculature and hemostatic system in rats after insonation.

Ultrasound, one of the most physically impactful factors of the modern human living environment, can cause hemodynamic changes in the microvasculature and the hemostatic system. Such shifts can be considered as possible predictors of cardiovascular diseases and their complications. This study aimed to examine the effect of 7-day in-air insonation on the microvasculature and hemostatic system of rats. The study included 28 male Wistar rats. A group of study animals was insonated over 7 days at a frequency of 25 kHz. The emitters were installed in a vertical position at a distance of 10 cm from both the sidewalls of a coarse wire cage. The sound pressure was 89.0 dB and power flux density was 7.73 ± 0.03 W/cm2. The microvasculature values of the study rats obtained by laser Doppler flowmetry were compared to those of control animals. To evaluate the hemostatic system, an integral research method, thromboelastography, was used. In the study rats, in response to 7-day insonation, statistically significant decreases in the active and passive factors of blood circulation modulation were observed compared to the control animals: microcirculation, flux, amplitude of endothelial and vasomotor vibrations, and amplitude of respiratory and pulse waves. According to the thromboelastography data, prolonged coagulation time at the initial stage and inhibited fibrinolytic activity were recorded. Thus, the study animals showed signs of a stress reaction based on changes in their microcirculatory parameters confirmed by increased serum concentrations of adrenocorticotropic hormone and cortisol and analysis of behavioral reactions in the open-field test.

Fetal Gene Therapy for Ornithine Transcarbamylase Deficiency by Intrahepatic Plasmid DNA-Micro-Bubble Injection Combined with Hepatic Ultrasound Insonation.

We evaluated the therapeutic efficacy of hepatic transfection of plasmid DNA using micro-bubbles and ultrasound insonation for fetal correction of ornithine transcarbamylase (OTC) deficiency in mice. Twenty-three sparse-fur heterozygous pregnant mice (day 16 of gestation) were divided into three groups: injection of plasmid-DNA micro-bubble mixture into fetal liver with ultrasound insonation (Tr, n = 11); control group 1 (C1), injection of plasmid-DNA micro-bubble mixture into fetal liver with no insonation (n = 5); and control group 2 (C2), injection of saline-micro-bubble mixture into fetal liver with ultrasound insonation (n = 7). Levels of blood ammonia and urinary orotic acid were significantly lower in the Tr group than in the C1 and C2 groups (p < 0.05, p < 0.01, respectively), whereas OTC activity was not different between groups. Therefore, ultrasound insonation with micro-bubbles enhanced plasmid DNA transfection into fetal mouse liver, leading to one of the therapeutic methods in ammonia metabolism. This might provide more time for OTC-deficient infants until liver transplantation.

Temporal bone thickness and texture are major determinants of the high rate of insonation failures of transcranial Doppler in Amerindians (the Atahualpa Project).

PURPOSE: To assess the role of temporal bone characteristics in transcranial Doppler (TCD) insonation failures in Amerindians living in rural Ecuador. METHODS: We evaluated thickness and texture of temporal bones in community-dwelling Amerindians ≥65 years old undergoing TCD. Using receiver operator characteristics curve analysis and generalized estimating equations, we investigated factors associated with insonation failures. RESULTS: Of 65 participants (mean age 74.7 ± 6.7 years, 60% women), 32 (49%) had uni- or bilateral insonation failure through temporal windows. Considering temporal bones independently, 57 of 130 (44%) had poor insonation. Mean thickness was higher (4.7 ± 1.2 versus 2.7 ± 0.9, p < 0.0001), and texture more often heterogeneous (93% versus 22%, p < 0.0001) in bones with poor acoustic windows. Thickness, better predicting poor insonation, was ≥3.6 mm if used alone, and ≥2.7 mm if used together with heterogeneous texture. For every millimeter of increase in thickness, subjects were 2.9 times more likely to have insonation failures. Per se, heterogeneous texture increased by 3.2 times the odds for poor insonation. In all models, being woman increased the odds for poor insonation by six to nine times. CONCLUSIONS: Temporal bone thickness and texture are independent predictors of TCD insonation failure in Amerindians.

Language of Transducer Manipulation: Codifying Terms for Effective Teaching.

There is a need for consistent, repetitive, and reliable terminology to describe the basic manipulations of the ultrasound transducer. Previously, 5 basic transducer motions have been defined and used in education. However, even with this effort, there is still a lack of consistency and clarity in describing transducer manipulation and motion. In this technical innovation, we describe an expanded definition of transducer motions, which include movements to change the transducer's angle of insonation to the target as well as the location on the body to optimize the ultrasound image. This new terminology may allow for consistent teaching and improved communication in the process of image acquisition.

Ultrasound sensitive eLiposomes containing doxorubicin for drug targeting therapy.

This study describes a novel nanocarrier of emulsion liposomes (eLiposomes) composed of a perfluoropentane nanodroplet within the aqueous interior of a DPPC liposome, along with the anticancer drug doxorubicin (Dox). The eLiposome containing Dox (eLipoDox) displayed good release of Dox upon insonation with low intensity ultrasound at 20-kHz, 1.0-MHz and 3.0-MHz. More release occurs in vitro at 20-kHz than at the higher frequencies. Controlled delivery was demonstrated by applying ultrasound (US) to HeLa tumor cells in vitro. The confocal images of Dox release to cells indicate that eLipoDox is an effective carrier of chemotherapeutic agent, and releases Dox to the cell cytosol upon insonation. This novel drug delivery system promises to provide more effective US therapy and tumor treatment and has the potential to reduce the side effects of cardiotoxicity caused by Dox. FROM THE CLINICAL EDITOR: In this paper, an ultrasound-sensitive doxorubicine-carrying nanoliposome delivery system is reported. Doxorubicin release as a result of ultrasound exposure is clearly demonstrated, paving the way to potential clinical applications with the aim of reducing the systemic toxicity and enhanced local delivery of this compound.