Ultrasound-assisted fermentation of Porphyra yezoensis sauce at different growth stages using Lactiplantibacillus plantarum: Metabolic response and biological activity

This study first employed ultrasonic-assisted fermentation of seaweed foot material with Lactiplantibacillus plantarum to produce Porphyra yezoensis sauce. The aim was to examine L. plantarum's growth and metabolism of nutritional components at different growth stages under low- (133.99 W/L) and high-ultrasonic power densities (169.17 W/L). After 24-h fermentation, L. plantarum exhibited a 21.32 % increase in the sonicated P. yezoensis sauce at 133.99 W/L and the logarithmic growth phase compared to that at 169.17 W/L. In addition, compared to the non-sonicated sauce, total phenolic and flavonoid contents increased by around 58 % and 27 % in sonicated sauce at 133.99 W/L, reaching 92.38 mg GEA/g DW and 111.08 mg RE/g DW, respectively. Principal Component Analysis (PCA) of the evaluation criteria for different fermentation stages under 133.99 W/L power ultrasonication revealed that the P. yezoensis sauce generated more phenolic compounds and exhibited stronger antioxidant capabilities in the sonicated sample at the logarithmic phase of L. plantarum. Compared to the traditional treated P. yezoensis sauce, the content of free amino acids was significantly increased in sonicated sauce, especially for logarithmic phase. Finally, GC-IMS analysis demonstrated that the ultrasonication at logarithmic phase released more volatile compounds compared to the non-sonicated sauce. This led to a reduction in the fishy odour of the Porphyra yezoensis sauce and an improved release of favourable flavour compounds.

Optimizing the use of low-frequency ultrasound for bacterial detachment of in vivo biofilms in dental research-a methodological study

OBJECTIVES

Low-frequency, low-intensity ultrasound is commonly utilized in various dental research fields to remove biofilms from surfaces, but no clear recommendation exists in dental studies so far. Therefore, this study aims to optimize the sonication procedure for the dental field to efficiently detach bacteria while preserving viability.

MATERIALS AND METHODS

Initial biofilm was formed in vivo on bovine enamel slabs (n = 6) which were worn by four healthy participants for 4 h and 24 h. The enamel slabs covered with biofilm were then ultrasonicated ex vivo for various time periods (0, 1, 2, 4, 6 min). Colony-forming units were determined for quantification, and bacteria were identified using MALDI-TOF. Scanning electron microscopic images were taken to also examine the efficiency of ultrasonications for different time periods.

RESULTS

Ultrasonication for 1 min resulted in the highest bacterial counts, with at least 4.5-fold number compared to the non-sonicated control (p < 0.05). Most bacteria were detached within the first 2 min of sonication, but there were still bacteria detached afterwards, although significantly fewer (p < 0.0001). The highest bacterial diversity was observed after 1 and 2 min of sonication (p < 0.03). Longer sonication periods negatively affected bacterial counts of anaerobes, Gram-negative bacteria, and bacilli. Scanning electron microscopic images demonstrated the ability of ultrasound to desorb microorganisms, as well as revealing cell damage and remaining bacteria.

CONCLUSIONS

With the use of low-frequency, low-intensity ultrasound, significantly higher bacterial counts and diversity can be reached. A shorter sonication time of 1 min shows the best results overall.

CLINICAL RELEVANCE

This standardization is recommended to study initial oral biofilms aged up to 24 h to maximize the outcome of experiments and lead to better comparability of studies.

Antibacterial and antibiofilm performance of low-frequency ultrasound against Escherichia coli O157:H7 and its application in fresh produce

Ultrasound technology has been focused on due to its unique advantages in biofilm removal compared with traditional antibacterial methods. Herein, the anti-biofilm properties of low-frequency ultrasound (LFUS) were studied against Enterohemorrhagic Escherichia coli O157: H7 (E. coli O157:H7). After ultrasonication (20 kHz, 300 W) for 5 min, the removal rate of biofilm from polystyrene sheets reached up to 99.999 %. However, the bacterial cells could not be inactivated completely even extending the duration of ultrasonic irradiation to 30 min. Fortunately, this study indicated that LFUS could efficiently weaken the metabolic capacity and biofilm-forming ability of bacterial cells separated from biofilm. It could be associated with the removal of cell surface appendages and damage to cell membrane induced by mechanical vibration and acoustic cavitation. Besides, the genetic analysis proved that the transcription level of genes involved in curli formation was significantly down-regulated during ultrasonic irradiation, thus impeding the process of irreversible adhesion and cells aggregation. Finally, the actual application effect of LFUS was also evaluated in different fresh produces model. The results of this study would provide a theoretical basis for the further application of ultrasound in the food preservation.

A phase I clinical trial of sonodynamic therapy combined with temozolomide in the treatment of recurrent glioblastoma

PURPOSE

The prognosis of recurrent glioblastoma (rGBM) is poor, and there is currently no effective treatment strategy. Sonodynamic therapy (SDT) is a new method for cancer treatment that uses a combination of low-frequency ultrasound and sonosensitisers to produce antitumor effects, which have shown good therapeutic effects in preclinical studies. Therefore, we initiated an open, prospective pilot study to evaluate the safety, tolerability, and efficacy of SDT for the treatment of rGBM.

METHODS

Nine patients with rGBM were enrolled who had received multiple treatments, but the nidus continued to progress without additional standard treatments. After MRI localisation, porphyrin drugs were injected, and intermittent low-frequency ultrasound therapy was performed for five days.

RESULTS

None of the nine patients in this clinical trial showed any clinical, neurological, haematological, or skin-targeted adverse effects associated with SDT. After the completion of the trial, one patient maintained stable disease, and eight patients experienced disease progression. Among the eight with progressive disease, the median progression-free survival time was 84 days. Four patients died, and the median overall survival duration after recurrence was 202.5 days.

CONCLUSION

The number of patients in this study was small; therefore, a long-term survival benefit was not demonstrated. However, this study suggests that SDT has potential as a treatment for rGBM and warrants further exploration. Trial information: Chinese Clinical Trial Registry ( http://www.chictr.org.cn/ ): ChiCTR2200065992. November 2, 2022, retrospectively registered.

Very Low Frequency Radial Modulation for Deep Penetration Contrast-Enhanced Ultrasound Imaging

Contrast-enhanced ultrasound imaging allows vascular imaging in a variety of diseases. Radial modulation imaging is a contrast agent-specific imaging approach for improving microbubble detection at high imaging frequencies (≥7.5 MHz), with imaging depth limited to a few centimeters. To provide high-sensitivity contrast-enhanced ultrasound imaging at high penetration depths, a new radial modulation imaging strategy using a very low frequency (100 kHz) ultrasound modulation wave in combination with imaging pulses ≤5 MHz is proposed. Microbubbles driven at 100 kHz were imaged in 10 successive oscillation states by manipulating the pulse repetition frequency to unlock the frame rate from the number of oscillation states. Tissue background was suppressed using frequency domain radial modulation imaging (F-RMI) and singular value decomposition-based radial modulation imaging (S-RMI). One hundred-kilohertz modulation resulted in significantly higher microbubble signal magnitude (63-88 dB) at the modulation frequency relative to that without 100-kHz modulation (51-59 dB). F-RMI produced images with high contrast-to-tissue ratios (CTRs) of 15 to 22 dB in a stationary tissue phantom, while S-RMI further improved the CTR (19-26 dB). These CTR values were significantly higher than that of amplitude modulation pulse inversion images (11.9 dB). In the presence of tissue motion (1 and 10 mm/s), S-RMI produced high-contrast images with CTR up to 18 dB; however, F-RMI resulted in minimal contrast enhancement in the presence of tissue motion. Finally, in transcranial ultrasound imaging studies through a highly attenuating ex vivo cranial bone, CTR values with S-RMI were as high as 23 dB. The proposed technique demonstrates successful modulation of microbubble response at 100 kHz for the first time. The presented S-RMI low-frequency radial modulation imaging strategy represents the first demonstration of real-time (20 frames/s), high-penetration-depth radial modulation imaging for contrast-enhanced ultrasound imaging.

Mechanism of low-frequency and high-frequency ultrasound-induced inactivation of soy trypsin inhibitors

In this study, the effect of ultrasonic frequency and power on the inactivation of soy trypsin inhibitors (TIs) was investigated to explore the ultrasound-induced inactivation mechanism. It was observed that 20 kHz and 355 kHz ultrasound have better inactivation efficiency than 1056 kHz. First-order rate constants for the inactivation process were obtained, which increased with increasing ultrasonic power at both 20 kHz and 355 kHz. For 20 kHz ultrasound, the formation of TI aggregates resulting from the physical effects of acoustic cavitation decreased the interactions between the active sites of TIs and trypsin, thus reducing the TI activity. For 355 kHz ultrasound, most of the methionine in the TIs was oxidised within 5 mins, resulting in a faster reduction of TI activity. Subsequent aggregation of TIs resulted in further TI inactivation. SDS-PAGE showed that neither disulphide bonds nor CC coupling were involved in the formation of aggregates.

Low-Frequency Sonophoresis as an Active Approach to Potentiate the Transdermal Delivery of Agomelatine-Loaded Novasomes: Design, Optimization, and Pharmacokinetic Profiling in Rabbits

The first melatonergic antidepressant drug, agomelatine (AGM), is commonly used for controlling major depressive disorders. AGM suffers low (< 5%) oral bioavailability owing to the hepatic metabolism. The current work investigated the potential of low-frequency sonophoresis on enhancing transdermal delivery of AGM-loaded novasomes and, hence, bioavailability of AGM. Drug-loaded novasomes were developed using free fatty acid (stearic acid or oleic acid), surfactant (span 60 or span 80), and cholesterol via thin-film hydration technique. The systems (N1-N16) were assessed for zeta potential (ZP), particle size (PS), encapsulation efficiency (EE%), and drug percent released after 0.5 h (Q_0.5 h) and 8 h (Q_8h), drug-crystallinity, morphology, and ex vivo drug permeation. Skin pre-treatment with low-frequency ultrasound (LFU) waves, via N13-novasomal gel systems, was optimized to enhance ex vivo drug permeation. Influences of LFU mode (continuous or pulsed), duty cycle (50% or 100%), and application period (10 or 15 min) were optimized. The pharmacokinetics of the optimized system (N13-LFU-C4) was assessed in rabbits. N13 was the best achieved novasomal system with respect to PS (471.6 nm), ZP (- 63.6 mv), EE% (60.5%), Q_0.5 h (27.8%), Q_8h (83.9%), flux (15.5 μg/cm²/h), and enhancement ratio (6.9). N13-LFU-C4 was the optimized novasomal gel system (desirability; 0.997) which involves skin pre-treatment with LFU in a continuous mode, at 100% duty cycle, for 15 min. Compared to AGM dispersion, the significantly (P < 0.05) higher flux (26.7 μg/cm²/h), enhancement ratio (11.9), C_max (118.23 ng/mL), and relative bioavailability (≈ 8.6 folds) could elucidate the potential of N13-LFU-C4 system in improving transdermal drug permeability and bioavailability.

High-intensity ultrasound-assisted recovery of anthocyanins from jabuticaba by-products using green solvents: Effects of ultrasound intensity and solvent composition on the extraction of phenolic compounds

This study proposes an update for the jabuticaba processing chain to obtain valuable coproducts from jabuticaba peels. High-intensity ultrasound (HIUS) technology was evaluated as a more efficient extraction process to obtain two high added-value coproducts: pectin and an anthocyanins-rich extract. The HIUS-assisted extraction of bioactive compounds like anthocyanins from the jabuticaba peels was evaluated. The effects of ultrasound intensity (1.1, 3.7, 7.3, and 13.0 W/cm²) and solvent composition concerning water/ethanol ratio (0, 25, 50, 75, and 100 g water/100 g) were examined. One-step HIUS processing promoted the best recovery of bioactive compounds at an ultrasound intensity of 3.7 W/cm² and 50 g water/100 g, thus proofing the interaction between ultrasound intensity and the solvent composition has a strong influence on the extraction efficiency of the groups of compounds studied and in the jabuticaba peel antioxidant potential. The confocal laser scanning microscopy confirmed bioactive compounds' exhaustion in the dried jabuticaba peel after the HIUS processing, proving its best recovery. The jabuticaba peel extract exhibited an intense reddish color typical of anthocyanin-rich products at acid pH (4.5). The HIUS technology turned out a promising way to recover these valuable phenolic compounds as a quick, relatively inexpensive, and simple technology that improves the yields and decreases the costs and environmental impacts compared to conventional extraction processes.

An investigation of mechanisms for the enhanced coagulation removal of Microcystis aeruginosa by low-frequency ultrasound under different ultrasound energy densities

There is a lack of studies elaborating the differences in mechanisms of low-frequency ultrasound-enhanced coagulation for algae removal among different ultrasound energy densities, which are essential to optimizing the economy of the ultrasound technology for practical application. The performance and mechanisms of low-frequency ultrasound (29.4 kHz, horn type, maximum output amplitude = 10 μm) -coagulation process in removing a typical species of cyanobacteria, Microcystis aeruginosa, at different ultrasound energy densities were studied based on a set of comprehensive characterization approaches. The turbidity removal ratio of coagulation (with polymeric aluminum salt coagulant at a dosage of 4 mg Al/L) was considerably increased from 44.1% to 59.7%, 67.0%, and 74.9% with 30 s of ultrasonic pretreatment at energy densities of 0.6, 1.11, and 2.22 J/mL, respectively, indicating that low-frequency ultrasound-coagulation is a potential alternative to effectively control unexpected blooms of M. aeruginosa. However, the energy density of ultrasound should be deliberately considered because a high energy density (≥18 J/mL) results in a significant release of algal organic matter, which may threaten water quality security. The specific mechanisms for the enhanced coagulation removal by low-frequency ultrasonic pretreatment under different energy densities can be summarized as the reduction of cell activity (energy density ≥ 0.6 J/mL), the slight release of negatively charged algal organic matter from cells (energy density ≥ 1.11 J/mL), and the aggregation of M. aeruginosa cells (energy density ≥ 1.11 J/mL). This study provides new insights for the ongoing study of ultrasonic pretreatment for the removal of algae via coagulation.

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 (dopamine_A1 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.

Experimental mouse model of NMOSD produced by facilitated brain delivery of NMO-IgG by microbubble-enhanced low-frequency ultrasound in experimental allergic encephalomyelitis mice

Although optic neuritis and myelitis are the core clinical characteristics of neuromyelitis optica spectrum disorders (NMOSD), appropriate animal models of NMOSD with myelitis and optic neuritis are lacking. we developed a mouse model of NMOSD by intravenously injecting 100 µg neuromyelitis optica immunoglobulin G antibody (NMO-IgG) and complement into experimental allergic encephalomyelitis (EAE) mice after reversible blood-brain barrier (BBB) opening by microbubble-enhanced low-frequency ultrasound (MELFUS). Animals were assessed by histopathology. We found noticeable inflammation and demyelination concomitant with the loss of aquaporin-4 (AQP4) and glial fibrillary acidic protein (GFAP) expression in the spinal cord, brain and optic nerve, as well as human IgG and C9neo deposition. Thus, with the help of MELFUS, we established an NMOSD mouse model with the core lesions of NMOSD by applying a considerably lower dose of human NMO-IgG, which may help identify the pathogenesis and facilitate the development of other neuroimmune disease models in the future.

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.

A randomized controlled trial of Chinese traditional medicine Dachengqi Decoction in the treatment of postoperative intestinal function recovery

BACKGROUND

Intestinal dysfunction is not conducive to the recovery of patients after surgery. It is particularly important to restore the intestinal function as soon as possible. In recent years, ultrasonic drug penetration therapy as a new type of non-invasive therapy has been used to solve this problem, but its efficacy has not been confirmed.

METHODS

Single-centre, parallel, randomized controlled clinical trial in China that included 184 patients undergoing laparoscopic gastrointestinal surgery. Ninety-one participants were randomly assigned to low-frequency ultrasound and electric pulses for transdermal drug delivery with Dachengqi Decoction (DCQD) (intervention group), and 90 were assigned to the control group after laparoscopic gastrointestinal surgery. The primary outcome was time to first flatus after surgery (by patient's subjective feeling). Secondary outcomes assessed the recovery time of bowel movement, time of the first defecation, postoperative gastrointestinal complications (e.g., nausea, vomit, and bloating), days of hospitalization and treatment costs.

RESULTS

Of 184 patients, 181 (98.4%) completed the trial. The sociodemographic characteristics and efficiency data were comparable in the two groups at baseline. The intervention group had a shorter mean time of bowel movement recovery than the control group [29.4 h (IQR, 22.0-35.0 h) vs. 33.7 h (IQR, 24.0-40.0 h; P=0.005)] and a shorter mean time to first flatus after surgery [35.8 h (IQR, 23.1-46.6 h) vs. 46.7 h (IQR, 25.9-61.3 h; P=0.012)]. Postoperative gastrointestinal reactions (e.g., nausea, vomit, and bloating) occurred in 28.6% in the intervention group and 43.3% in the control group (P=0.038). Two patients in the intervention group had electrical tingling sensations, and one patient had a skin rash during the treatment. There were no significant differences in the occurrence rates of AEs or SAE, days of hospitalization and treatment costs between the two groups.

CONCLUSIONS

Low-frequency ultrasound and electric pulses for transdermal drug delivery with DCQD can shorten the time of bowel movement recovery and accelerate first anal exhaust after laparoscopic gastrointestinal surgery.

TRAIL REGISTRATION

Chictr.org.cn Identifier: ChiCTR-IPR-17013630.

Effect of low-frequency ultrasound on the particle size, solubility and surface charge of reconstituted sodium caseinate

Low-frequency sonication (20 kHz) was applied to sodium caseinate suspensions (4%, 7% and 10% protein concentrations) at pH 4.0, 4.6, 6.7 and 9.0. Particle size, zeta potential and solubility analysis were used to evaluate the physical changes of the sodium caseinate suspensions before and after the application of ultrasound. At pH 6.7 the particle size remained between 5 and 7 µm for all concentrations before and after sonication (15-400 J/mL), resulting in no significant change (p > 0.05). Similarly, sonication did not significantly (p > 0.05) affect the solubility at pH 6.7. At this pH, the initial solubility was high at 94-98% (w/w) before sonication. At pH 9.0 for 4% and 7% concentrations, suspensions became more negatively charged and the initial particle size increased to 78-82 µm. In the presence of larger suspensions, the application of ≥15 J/mL reduced the particle size to less than 2 µm. By contrast to pH 6.7, the solubility at pH 9.0 for 4% and 7% protein suspensions reached 99% before and after sonication. Viscosity was the highest (80 mPa.s at 15 sec^-1) for a 10% protein concentration at pH 9.0. As the protein concentration of the sodium caseinate suspensions decreased from 10% to 4% at pH 9.0, the viscosity of the suspensions also decreased. However, application of low-frequency ultrasound had no effect on the viscosity of the sodium caseinate suspensions. Due to the absence of large insoluble aggregates in reconstituted sodium caseinate suspensions, the overall effect of low-frequency sonication were largely insignificant at native pH and only became evident at outlier pH values when the casein proteins associate.

Assessment of a low-frequency ultrasound device on prevention of biofilm formation and carbonate deposition in drinking water systems

A device generating low-frequency and low-intensity ultrasound waves was used for mitigating biofilm accumulation and scaling. Two systems were tested: a lab-scale plate heat exchanger operated with continuously recycled water and a continually fed flow-through drinking water pilot used for mimicking water circulation in pipes. Initial deposition of bacterial cells was not prevented by ultrasound wave treatment. However, whatever the tested system, both further calcium carbonate deposition and biofilm growth were markedly inhibited. Biofilms formed in reactors subjected to low-frequency and low-intensity ultrasound waves were weakly attached to the material. Even though the activity of bacteria was affected as shown by their lower cultivability, membrane permeability did not appear compromised. Ultrasound technology sounds very promising in both the mitigation of drinking water biofilm and carbonate accumulation.

Feasibility of low-frequency ultrasound imaging using pulse compressed parametric ultrasound

When using high-frequency (HF) ultrasound in sonography, attenuation due to the viscosity of the medium limits the available imaging depth, and strong reflection and scattering from hard tissue, such as bone, render biological diagnosis very difficult. In order to resolve these problems, the feasibility of low-frequency (LF) parametric ultrasound imaging with high directivity was explored in the present study. A pulse compression technique was applied to chirp-modulated parametric ultrasound waves in the frequency band of 100-500 kHz generated from modulated primary ultrasound waves with a center frequency of 2.8 MHz in order to improve the signal-to-noise ratio (SNR). Low-frequency ultrasound images of brass rods obtained using pulse compressed parametric ultrasound exhibit accurate target distances, a 3-mm range resolution, which agrees well with the theoretical value, and an 8-dB improvement in SNR. Parametric ultrasound imaging with pulse compression makes easy to separate overlapping targets in comparison with HF ultrasound imaging, and indicates the image with brightness independent of distance in comparison with directly radiated LF ultrasound imaging. These results reveal that pulse compressed LF parametric ultrasound is not only a useful method for improving the SNR and providing accurate distance measurements, but also enables imaging of overlapping targets.

Ultrasound-enhanced electrokinetic remediation for removal of Zn, Pb, Cu and Cd in municipal solid waste incineration fly ashes

Low-frequency ultrasound generated by a transducer was investigated to activate the raw municipal solid waste incineration (MSWI) fly ashes in the electrokinetic process, aiming at enhancing heavy metal (HM) removal and achieving better remedial efficacy. The maximum removal efficiencies of 69.84%, 64.24%, 67.74% and 59.93% were obtained in the orthogonal tests of ultrasonication for Zn, Pb, Cu and Cd, respectively. The acoustic time of 30 min and controlling temperature of 45 °C in the operating parameters were quantitatively determined to optimize the ultrasonication of the MSWI fly ash matrices. The changes of acoustic time had a significant effect on the extraction efficiencies of all the four heavy metal elements in the sonication optimal experiments. The longer running time was preferred for the pretreatment of the fly ashes in according to the marginal mean removal results. The voltage gradient of 2 V/cm was most likely to improve the removals of four HMs during the electrokinetics in the range of 0.5-2 V/cm. The synergetic application of acidification and ultrasonication for the media treatment was demonstrated to be most effective in enhancing the remedial efficiencies in the further electrokinetic experiments compared with the other activation systems. Correspondingly, the leaching concentrations of Zn, Pb, Cu and Cd in the samples were reduced by 85.92%, 98.22%, 88.53% and 98.34%, respectively. The contaminants were continuously extracted from the solid grains of the fly ashes by the protonic attack and bubble implosion. The obtained risk-assessment-code values indicated the adoption of AUS-EKR system reduced the environmental toxicity for the fly ashes to the maximum extent.

The use of 5-fluorouracil-loaded nanobubbles combined with low-frequency ultrasound to treat hepatocellular carcinoma in nude mice

OBJECTIVE

This study aimed to investigate the therapeutic effects of 5-fluorouracil (5-FU)-loaded nanobubbles irradiated with low-intensity, low-frequency ultrasound in nude mice with hepatocellular carcinoma (HCC).

METHODS

A transplanted tumor model of HCC in nude mice was established in 40 mice, which were then randomly divided equally into four groups: group A (saline), group B (5-FU-loaded nanobubbles), group C (5-FU-loaded nanobubbles with non-low-frequency ultrasound), and group D (5-FU-loaded nanobubbles with low-frequency ultrasound). The tumor size in each mouse was observed via ultrasound before and after the treatments. Inhibition of the tumor growth in each group was compared, and survival curves were generated. Tumor tissues were removed to determine the apoptotic index using the TUNEL method and quantitative analysis. Tumor tissues with CD34-positive microvessels were observed by immunohistochemistry, and the tumor microvessel densities were calculated.

RESULTS

The growth rate of the tumor volumes in group D was significantly slower than that in the other groups, while the tumor inhibition rates and apoptotic index in group D were significantly higher than those of the other groups. The number of microvessels staining positive for CD34 was decreased in group D. Therefore, group D presented the most significant inhibitory effects.

CONCLUSIONS

Therefore, 5-FU-loaded nanobubbles subjected to irradiation with low-frequency ultrasound could further improve drug targeting and effectively inhibit the growth of transplanted tumors, which is expected to become an ideal drug carrier and targeted drug delivery system for the treatment of HCC in the future.

Defining optimal permeant characteristics for ultrasound-mediated gastrointestinal delivery

Ultrasound-mediated drug delivery in the gastrointestinal (GI) tract is a bourgeoning area of study. Localized, low-frequency ultrasound has recently been shown to enable significant enhancement in delivery of a broad set of active pharmaceutical ingredients including small molecules, proteins, and nucleic acids without any formulation or encapsulation of the therapeutic. Traditional chemical formulations are typically required to protect, stabilize, and enable the successful delivery of a given therapeutic. The use of ultrasound, however, may make delivery insensitive to the chemical formulation. This might open the door to chemical formulations being developed to address other properties besides the deliverability of a therapeutic. Instead, chemical formulations could potentially be developed to achieve novel pharmacokinetics, without consideration of that particular formulation's ability to penetrate the mucus barrier passively. Here we investigated the effect of permeant size, charge, and the presence of chemical penetration enhancers on delivery to GI tissue using ultrasound. Short ultrasound treatments enabled delivery of large permeants, including microparticles, deep into colonic tissue ex vivo. Delivery was relatively independent of size and charge but did depend on conformation, with regular, spherical particles being delivered to a greater extent than long-chain polymers. The subsequent residence time of model permeants in tissue after ultrasound-mediated delivery was found to depend on size, with large microparticles demonstrating negligible clearance from the local tissue 24h after delivery ex vivo. The dependence of clearance time on permeant size was further confirmed in vivo in mice using fluorescently labeled 3kDa and 70kDa dextran. The use of low-frequency ultrasound in the GI tract represents a novel tool for the delivery of a wide-range of therapeutics independent of formulation, potentially allowing for the tailoring of formulations to impart novel pharmacokinetic profiles once delivered into tissue.

Performance and mechanism of phycocyanin removal from water by low-frequency ultrasound treatment

Ultrasonication pretreatment of raw water with high content of algal cells might cause an increase in dissolved organic nitrogen (DON) and proteins, which must be removed effectively before coagulation. In this study, the efficiency of sonication treatment in removing typical proteins derived from algal cells was investigated by applying ultrasonic waves at 20, 40, 60, 80, and 100kHz, and the influencing factors and removal mechanism were discussed. The results showed that low-frequency sonication could degrade phycocyanin to some extent, achieving about 95% removal rate after 150min of sonication. However, excitation emission matrix analysis indicated that ultrasonication could not entirely degrade phycocyanin into inorganic nitrogen, and many proteins and nitrogen-containing organics were found in the samples after sonication. While the total nitrogen concentration remained consistent during the entire sonication process (240min), the total inorganic nitrogen concentration increased from 0.6 to 1.3mg/L, indicating that only 33.3% of DON was oxidized into inorganic nitrogen. Nevertheless, sonication could significantly attenuate the interference of phycocyanin in coagulation and enhance coagulation. The mechanical effects and free-radical oxidation resulting from cavitation collapse could be responsible for the degradation of phycocyanin and proteins following sonication. In all, the use of ultrasonic treatment as a posttreatment following sonication to remove algal cells from raw water may not be beneficial.

Low-Frequency Ultrasound Enhances Antimicrobial Activity of Colistin-Vancomycin Combination against Pan-Resistant Biofilm of Acinetobacter baumannii

Acinetobacter baumannii biofilms in catheters are very difficult to treat. Low-frequency ultrasound (LFU) may improve bactericidal or bacteriostatic activity. However, no previous studies have been reported on its efficacy against pan-resistant biofilms of A. baumannii. This study was designed to investigate whether LFU can enhance the activity of colistin, vancomycin and colistin-vancomycin combinations against pan-resistant biofilms of A. baumannii. The efficacy of colistin combinations was determined using the fractional inhibitory concentration index (FICI). The antibacterial effect was determined from bacteria counts in biofilms and the establishment of 24-h time-kill curves. A significantly synergistic effect was detected between colistin and vancomycin (FICI <0.05). We found that although application of LFU (40 kHz, 600 mW/cm(2), 30 min, duty cycle 1:9) alone or in combination with a single agent failed to significantly reduce bacteria counts in biofilms, it apparently enhanced the antibacterial effectiveness of combinations of these agents. Moreover, higher concentrations of colistin in the combination treatments resulted in a better ultrasound-enhanced antibacterial effect. In 24-h time-kill curves, the combination of colistin (8 μg/mL) plus vancomycin (4 μg/mL) with LFU caused a significant reduction in bacteria counts in biofilms after 8 h and a continuing decline until 24 h. Bacterial counts were reduced by 3.77 log(CFU/mL) by LFU plus combinations, compared with combinations without LFU at 24 h. Our results indicate that LFU in combination with colistin plus vancomycin may be useful in treating pan-resistant A. baumannii infections.

Enhanced therapeutic anti-inflammatory effect of betamethasone on topical administration with low-frequency, low-intensity (20 kHz, 100 mW/cm(2)) ultrasound exposure on carrageenan-induced arthritis in a mouse model

The purpose of this work was to investigate whether low-frequency, low-intensity (20 kHz, <100 mW/cm(2), spatial-peak, temporal-peak intensity) ultrasound, delivered with a lightweight (<100 g), tether-free, fully wearable, battery-powered applicator, is capable of reducing inflammation in a mouse model of rheumatoid arthritis. The therapeutic, acute, anti-inflammatory effect was estimated from the relative swelling induced in mice hindlimb paws. In an independent, indirect approach, the inflammation was bio-imaged by measuring glycolytic activity with near-infrared labeled 2-deoxyglucose. The outcome of the experiments indicated that the combination of ultrasound exposure and topical application of 0.1% (w/w) betamethasone gel resulted in statistically significantly (p < 0.05) enhanced anti-inflammatory activity in comparison with drug or ultrasound treatment alone. The present study underscores the potential benefits of low-frequency, low-intensity ultrasound-assisted drug delivery. However, the proof of concept presented indicates the need for additional experiments to systematically evaluate and optimize the potential of, and the conditions for, tolerable low-frequency, low-intensity ultrasound-promoted non-invasive drug delivery.

Inactivation of Enterobacter aerogenes in reconstituted skim milk by high- and low-frequency ultrasound

The inactivation of Enterobacter aerogenes in skim milk using low-frequency (20kHz) and high-frequency (850kHz) ultrasonication was investigated. It was found that low-frequency acoustic cavitation resulted in lethal damage to E. aerogenes. The bacteria were more sensitive to ultrasound in water than in reconstituted skim milk having different protein concentrations. However, high-frequency ultrasound was not able to inactivate E. aerogenes in milk even when powers as high as 50W for 60min were used. This study also showed that high-frequency ultrasonication had no influence on the viscosity and particle size of skim milk, whereas low-frequency ultrasonication resulted in the decrease in viscosity and particle size of milk. The decrease in particle size is believed to be due to the breakup of the fat globules, and possibly to the cleavage of the κ-casein present at the surface of the casein micelles. Whey proteins were also found to be slightly affected by low-frequency ultrasound, with the amounts of α-lactalbumin and β-lactoglobulin slightly decreasing.