Effects of low-intensity ultrasound on gramicidin D-induced erythrocyte edema

Low-intensity ultrasound attenuates paw edema formation and decreases vascular permeability induced by carrageenan injection in rats

Background

Therapeutic potential of low-intensity ultrasound (LIUS) has become evident in various musculoskeletal diseases. We have previously shown that LIUS has an inhibitory effect on local edema in various diseases including the arthritis and brain injury. In this study, we examined whether LIUS can attenuate paw edema formation vis-à-vis vascular permeability and inflammation in rats induced by carrageenan. LIUS with a frequency of 1 MHz and the intensities of 50, 100, or 200 mW/cm² were exposed on rat paws for 10 min immediately after carrageenan injection.

Results

Carrageenan injection induced paw edema which was peaked at 6 h and gradually decreased nearly to the initial baseline value after 72 h. LIUS showed a significant reduction of paw edema formation at 2 and 6 h at all intensities tested. The highest reduction was observed at the intensity of 50 mW/cm². Histological analyses confirmed that LIUS clearly decreased the carrageenan-induced swelling of interstitial space under the paw skin and infiltration of polymorphonuclear leukocytes. Moreover, Evans Blue extravasation analyses exhibited a significant decreases of vascular permeability by LIUS. Finally, immunohistochemical staining showed that expression of pro-inflammatory proteins, namely, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) induced by carrageenan injection was reduced back to the normal level after LIUS stimulation.

Conclusions

These results provide a new supporting evidence for LIUS as a therapeutic alternative for the treatment of edema in inflammatory diseases such as cellulitis.

A Miniaturized Low-Intensity Ultrasound Device for Wearable Medical Therapeutic Applications

Low-intensity ultrasound has drawn increasing attention recently as a non-invasive modality for medical therapeutic applications. Current commercially available low-intensity ultrasound devices are bulky and expensive. In this paper, a battery-powered miniaturized device is proposed to generate low-intensity therapeutic ultrasound. The proposed device consists of a custom Application-Specific Integrated Circuit (ASIC), an off-chip digital control block, and a piezoelectric transducer. The ASIC, which integrates a DC-DC boost converter and a transducer driver, is implemented in TSMC's 0.18  μm BCD Gen2 process. Measurement results show that a maximum output voltage of 14 V is achieved by the proposed fully-integrated DC-DC boost converter with a battery supply voltage of 3.7 V. The peak power conversion efficiency is 29% and the output power at the peak power conversion efficiency is 105 mW. The on-chip transducer driver employs a half-bridge circuit with two n-type devices at the output stage. A high-voltage level shifter with low power consumption and short propagation delay is proposed in this paper for the high-performance operation of the half-bridge transducer driver. The piezoelectric transducer is a customized transducer with a resonance frequency of 1.5 MHz. At this frequency, the proposed low-intensity ultrasound device is able to generate continuous-wave ultrasound with a therapeutic power intensity of 32 [Formula: see text]. The proposed low-intensity ultrasound device is low-cost, compact, and light-weight, which enables affordable, and wearable applications.

Low-Intensity Ultrasound Enhances Histone Acetylation and Inhibition of Interleukin 6 Messenger RNA Expression by the Histone Deacetylase Inhibitor Sodium Butyrate in Fibroblasts

OBJECTIVES

Sodium butyrate, an inhibitor of histone deacetylase, has several therapeutic actions, including anti-inflammation. These actions depend on the concentration of sodium butyrate. In addition, lower concentrations have shown no effect on inflammation. Sonoporation by ultrasound can modify the permeability of the cell plasma membrane. Thus, the effects of sodium butyrate may be enhanced by the ultrasonic acoustics. Therefore, the facilitative effects of low-intensity ultrasound on histone acetylation and interleukin 6 (IL-6) regulation by sodium butyrate were investigated in this study.

METHODS

Human dermal fibroblasts were treated with 1-mM sodium butyrate for 3 hours with 20 minutes of 0.1-W/cm² pulsed or continuous ultrasound irradiation at the beginning of the sodium butyrate treatments.

RESULTS

The combination of treatments with sodium butyrate and ultrasound significantly increased histone acetylation in fibroblasts (P < .05), whereas sodium butyrate could not increase histone acetylation. In addition, this combined treatment significantly suppressed the IL-6 messenger RNA expression level with lipopolysaccharide stimulation for 1 hour (P < .05). Meanwhile, the treatment with sodium butyrate alone could not suppress IL-6 messenger RNA expression in fibroblasts. These effects were achieved with both 20% pulsed and continuous ultrasound but not observed with ultrasound treatment alone.

CONCLUSIONS

These results suggest that low-intensity ultrasound treatment promotes the physiologic actions of sodium butyrate as a histone deacetylase inhibitor.