Duration Of Ultrasound Exposure Research Articles

Effects of ultrasound on the extraction of antioxidants from bearberry (Arctostaphylos adans) leaves

The effects of ultrasound (f = 60 kHz) on the quantity of biologically active substances extracted from bearberry leaves into a water:ethanol (1:1) mixture were studied, along with their antioxidant properties. The optimal conditions for extract preparation were identified: the raw material:extractant ratio and the duration of ultrasound exposure. Positive and negative aspects of the ultrasound extraction of antioxidants are discussed. The antioxidant activity of the extract prepared in optimum conditions was greater than that of a bearberry leaf extract prepared without ultrasound, increasing the resistance of sunflower oil to oxidation by factors of 2–2.2.

Phospholipids-based microbubbles sonoporation pore size and reseal of cell membrane cultured in vitro

Objective: To investigate phospholipids-based microbubbles induced sonoporation and cell membrane reseal in vitro under various conditions.Methods: A breast cancer cell line SK-BR-3 was used to investigate ultrasonic sonoporation under various conditions. Atomic force microscopy (AFM) scanning techniques were employed to observe the change of membrane pores.Results: Normal SK-BR-3 cells membrane pores were evenly distributed and less than 1 μm. After ultrasound exposure, membrane pores were enlarged at different degree depending on ultrasound exposure durations, filling gas species and microbubble suspension concentration. With microbubble suspension concentration being increased to 5% or ultrasound exposure reached 30 s, membrane pores in fluorocarbon (C3F8 or SF6)-filled microbubble groups exceeded 1 μm, which were significantly larger than that of air-filled microbubble group. Membrane pores were about 2–3 μm under ultrasound 60 s with 5% fluorocarbon-filled microbubble suspension. After 24 h of incubation, most of the enlarged membrane pores could reseal to normal size, which corresponded to cell viability.Conclusions: Membrane pores can be obviously enlarged by ultrasonic sonoporation of fluorocarbon-filled microbubbles, whose reseal time depended on ultrasound exposure duration and microbubble suspension concentration.

Myocardial delivery of colloid nanoparticles using ultrasound-targeted microbubble destruction

Ultrasound (US)-targeted microbubble destruction (UTMD) is a promising method for delivering genetic material to the heart. The aim of this study was: (i) to test whether colloid nanoparticles can be delivered to the rat myocardium using UTMD; and (ii) to determine whether tissue damage and contractile dysfunction occurs in hearts exposed to UTMD in vivo. Hearts from anaesthetized rats were exposed to perfluorocarbon-enhanced sonicated dextrose albumin (PESDA) (at two different microbubble concentrations) and US at peak pressures of 0.6, 1.2, or 1.8 MPa for 1, 3, or 9 min. During US, pairs of 30 and 100 nm fluorescent nanospheres were infused intravenously. Left ventricular function was assessed before and immediately after US, as well as at 24 h and 7 days. At the end of the experiments, the number of ruptured microvessels and the amount of nanospheres deposited were quantified. Rats exposed to PESDA alone or US alone showed no functional abnormalities, no capillary ruptures, and no nanosphere delivery. In contrast, rats exposed to both PESDA and US exhibited microvascular ruptures and nanosphere deposits. They also showed transient contractile dysfunction and premature ventricular contractions. All these changes were time-, US peak pressure-, and PESDA concentration-dependent. UTMD allows colloid nanoparticles to be delivered to the rat myocardium through microvessel rupture sites. The efficacy of delivery depends on the peak pressure applied, the duration of US exposure, and contrast concentration. UTMD also causes time- and peak pressure-dependent contractile dysfunction, and tissue alterations that are spontaneously reversible over time.

In vitro modulation of intracellular oxidative stress of endothelial cells by diagnostic cardiac ultrasound.

Diagnostic cardiac ultrasound are commonly assumed to pose no hazard to the patient-but this is not synonymous with being biologically inert. The production of intracellular reactive oxygen species (ROS) on endothelial cells is a key modulator of atheroprotective (at low level) and atherogenic (at high levels) actions. The aim of the study was to evaluate in vitro the effects on intracellular ROS of endothelial cells after ultrasound exposure of variable duration with commercially available cardiac imaging systems. Endothelial cells fluorescence was evaluated in vitro after sham (transducer off) exposure to ultrasound and after 5', 15' and 30' of ultrasound irradiation with second harmonic 1.3/2.6 MHz cardiac ultrasound scan (mechanical index 1.5). Intracellular ROS were 83 at baseline, and rose to 86, 112 and 122 fluorescence intensity at 1 h incubation after 5', 15' and 30' of ultrasound exposure respectively (P<0.01 for 30' versus baseline and 5' comparison). There were microscopic signs of endothelial damage only following 30' stage. Ultrasound exposure induced significant DNA laddering and LDH leakage after 15' of ultrasound exposure. Effects on endothelial cells could be reproduced by adding exposed extracellular medium to unexposed cells, and could be prevented removing exposed medium from cell culture or pretreating the medium with catalase. Cardiac ultrasound of current clinical diagnostic use increases intracellular oxidative stress on endothelial cells in vitro. This increase is accompanied by morphological evidence of endothelial damage only after longer exposure times, persists 1 h after withdrawal of ultrasound, and can be modulated over a wide range according to the duration of ultrasound exposure. Free radical production in the extracellular medium is the likely mediator of ultrasound effect.

Sister Chromatid Exchanges in Cultured Amniocytes Exposed to Diagnostic Ultrasound in Vitro

An in vitro system has been set up to study the possible genetic effects of diagnostic ultrasound (US) on the developing fetus. Amniotic cells were cultured by the in situ technique. Well established clones were exposed to US for various lengths of time using a linear array transducer within a sound transparent apparatus. Cells were then grown in the presence of 5-bromo-2'-deoxyuridine and processed for scoring the number of sister chromatid exchanges (SCE) as the cytogenetic endpoint. There was no linear relationship between the SCE frequency and the duration of US exposure. Variance analysis showed that only interindividual variability was a significant component of total variation. Neither the main effect of treatment nor the interaction effect were statistically significant. The data suggest that US delivered from a diagnostic unit to actively growing cultured fetal cells in a system closely mimicking the conditions of US exposure during amniocentesis does not induce SCE.

Confirmation of an ultrasound-induced mutation in two in-vitro mammalian cell lines

In-vitro V79 and L5178Y cells were exposed in a rotating test tube to continuous-wave (CW) 1 MHz 35 W/cm 2 ultrasound (0–4 or 0–3 min, respectively) and subsequently assayed for mutation as evidenced by resistance to 6-thioguanine (6-TG). There was a modest but statistically significant increase in mutation frequency in both cell types with increase in ultrasound exposure duration. X-ray exposures (3-9 Gy, a “positive control”) yielded a large increase in 6-TG resistance. The data support an earlier report by Kaufman (1985) of an ultrasound-induced increase in mutation to 6-TG resistance in in-vitro mammalian cells.