EPR analysis of radicals generated in ultrasound-assisted lipoplasty simulated environment

Medium-high frequency sonication dominates spherical-SiO2 nanoparticle size

Spherical SiO₂ nanoparticles (SSNs) have been inventively synthesized using the Stöber method with sonication at medium-high frequencies (80, 120, and 500 kHz), aiming to control SSN size and shorten reaction time. Compared to the conventional method, such sonication allowed the Stöber reaction complete in 20-60 min with a low molar ratio of NH₄OH/tetraethyl orthosilicate (0.84). The hydrodynamic diameters of 63-117 nm of SSNs were obtained under sonication with 80, 120, and 500 kHz of ultrasonic frequencies. Moreover, the SSNs obtained were smaller at 120 kHz than at 80 kHz in a multi-frequencies ultrasonic reactor, and the SSN size decreased with increasing ultrasonic power at 20 °C, designating the sonochemical unique character, namely, the SSN-size control is associated with the number of microbubbles originated by sonication. With another 500 kHz ultrasonic bath, the optimal system temperature for producing smaller SSNs was proven to be 20 °C. Also, the SSN size decreased with increasing ultrasonic power. The smallest SSNs (63 nm, hydrodynamic diameter by QELS, or 21 nm by FESEM) were obtained by sonication at 207 W for 20 min at 20 °C. Furthermore, the SSN size increased slightly with increasing sonication time and volume, favoring the scale-up of SSNs preparation. The mechanisms of controlling the SSN size were further discussed by the radical's role and effects of ammonia and ethanol concentration.

32 Years of Ultrasonic-Assisted Lipoplasty (U.A.L.): From Aesthetic to Obesity

In this article, we tried to take stock of the state of the art in ultrasonic-assisted lipoplasty focusing on its most recent technologic advances and in the newest clinical applications, such as overweight, obesity, breast surgery and regenerative medicine. Great space was devoted to the analysis and clarification of the most common myths and legends related to this intriguing technique.

Isolation of human adipose-derived stromal cells using laser-assisted liposuction and their therapeutic potential in regenerative medicine

Harvesting adipose-derived stromal cells (ASCs) for tissue engineering is frequently done through liposuction. However, several different techniques exist. Although third-generation ultrasound-assisted liposuction has been shown to not have a negative effect on ASCs, the impact of laser-assisted liposuction on the quality and differentiation potential of ASCs has not been studied. Therefore, ASCs were harvested from laser-assisted lipoaspirate and suction-assisted lipoaspirate. Next, in vitro parameters of cell yield, cell viability and proliferation, surface marker phenotype, osteogenic differentiation, and adipogenic differentiation were performed. Finally, in vivo bone formation was assessed using a critical-sized cranial defect in athymic nude mice. Although ASCs isolated from suction-assisted lipoaspirate and laser-assisted lipoaspirate both successfully underwent osteogenic and adipogenic differentiation, the cell yield, viability, proliferation, and frequency of ASCs (CD34(+)CD31(-)CD45(-)) in the stromal vascular fraction were all significantly less with laser-assisted liposuction in vitro (p < .05). In vivo, quantification of osseous healing by micro-computed tomography revealed significantly more healing with ASCs isolated from suction-assisted lipoaspirate relative to laser-assisted lipoaspirate at the 4-, 6-, and 8-week time points (p < .05). Therefore, as laser-assisted liposuction appears to negatively impact the biology of ASCs, cell harvest using suction-assisted liposuction is preferable for tissue-engineering purposes.

On the efficiency of water soluble antioxidants

The wide use of high intensity ultrasound (HIU) in modern medicine raises the question of bio-safety. It has been shown that the effect of HIU in biological media may have similarity to the effects of ionizing radiation. Exposure of biological media to HIU field may lead to cavitation phenomenon followed by formation of free radicals such as hydroxyl radical (OH(·)) and the super-oxide ion (O(2)(·-)). These are highly reactive species that may cause harmful effects and induce oxidative stress. In the present study we employed electron spin resonance (ESR) spectroscopy together with spin traps to quantify the dynamics of hydroxyl radical formation during exposure to HIU field in the presence of different amounts of six antioxidants. Thus, the efficiency of water-soluble antioxidants, namely Allicin, Melatonin, Deoxyribose, Trolox, Nuphlutine and Hermidin, to suppress accumulation of OH radicals was examined. The results show that among the six, Trolox and Allicin reduce hydroxyl concentration with the highest efficiency.

Adipose tissue-derived mesenchymal stem cell yield and growth characteristics are affected by the tissue-harvesting procedure

BACKGROUND

Adipose tissue contains a stromal vascular fraction that can be easily isolated and provides a rich source of adipose tissue-derived mesenchymal stem cells (ASC). These ASC are a potential source of cells for tissue engineering. We studied whether the yield and growth characteristics of ASC were affected by the type of surgical procedure used for adipose tissue harvesting, i.e. resection, tumescent liposuction and ultrasound-assisted liposuction.

METHODS

Frequencies of ASC in the stromal vascular fraction were assessed in limiting dilution assays. The phenotypical marker profile of ASC was determined, using flow cytometry, and growth kinetics were investigated in culture. ASC were cultured under chondrogenic and osteogenic conditions to confirm their differentiation potential.

RESULTS

The number of viable cells in the stromal vascular fraction was affected by neither the type of surgical procedure nor the anatomical site of the body from where the adipose tissue was harvested. After all three surgical procedures, cultured ASC did express a CD34+ CD31- CD105+ CD166+ CD45- CD90+ ASC phenotype. However, ultrasound-assisted liposuction resulted in a lower frequency of proliferating ASC, as well as a longer population doubling time of ASC, compared with resection. ASC demonstrated chondrogenic and osteogenic differentiation potential.

DISCUSSION

We conclude that yield and growth characteristics of ASC are affected by the type of surgical procedure used for adipose tissue harvesting. Resection and tumescent liposuction seem to be preferable above ultrasound-assisted liposuction for tissue-engineering purposes.

Sonochemically induced covalent binding of calf thymus DNA by aziridinylquinones

Sonolysis of argon- or oxygen-containing samples in the presence of calf thymus DNA and the diaziridinylquinones 2,5-bis-aziridin-1-yl-3,6-dichloro-1,4-benzoquinone (AZClQ) and 2,5-bis(carboethoxyamino)-3,6-diaziridinyl-1,4-benzoquinone (AZQ) produced quinone-DNA covalent adducts at pH 5.5 and to a much lesser extent at pH 7.4. The corresponding semiquinone derivatives are detected using EPR spectroscopy after sonolysis of argon-saturated solutions at pH 7.4. The amount of covalent adducts decreases with addition of SOD, indicating a role of superoxide in this process. Addition of oxygen to the purging gas decreased but did not eliminate this covalent adduct. Thus this work suggests a possible synergism between bioreductive quinones and ultrasound in antitumor therapies based on alkylating quinone-DNA adduct formation with potential applications to both hypoxic and normally oxygenated conditions.

Acoustic cavitation in phacoemulsification and the role of antioxidants

Cataract surgery by phacoemulsification generates acoustic cavitation, resulting in formation of reactive oxygen species. The aim of this study was to establish the mechanism of damage by phacoemulsification in an in vitro setting simulating cataract surgery and to assess the protective effects of water-soluble antioxidants. Electron paramagnetic resonance spectroscopy was used to analyze generation of radicals in an intraocular irrigating solution by phacoemulsification instrumentation, operating at an ultrasonic frequency range of 40--60 kHz. Hydroxyl radicals were generated by phacoemulsification under conditions simulating cataract surgery. The effects of water-soluble antioxidants in the irrigating solution on the amounts of radicals were evaluated by electron paramagnetic resonance spectroscopy. The water-soluble antioxidant glutathione, applied in either oxidized or reduced form, decreased hydroxyl radicals concentration measured in the sonicated medium. The effective concentrations of oxidized and reduced glutathione in irrigating solution that significantly eliminate the hydroxyl radical signal were determined in the range of 10(-3)-10(-2) M. Antioxidants should be applied clinically to reduce damage to the corneal endothelium induced by phacoemulsification, thereby improving biosafety.

Acoustic cavitation in phacoemulsification: chemical effects, modes of action and cavitation index

High-intensity ultrasound (US) energy (HIUE) has been extensively used in the last 3 decades in a wide range of surgical procedures, including phacoemulsification. The generation of radicals and sonoluminescence (SL) by application of continuous-wave (CW) HIUE to an aqueous medium under conditions simulating cataract phacoemulsification surgery is demonstrated by electron paramagnetic resonance (EPR) spectroscopy and a sensitive photon-detecting system. The findings provide direct evidence for the generation of acoustic cavitation in the simulated intraocular environment, pointing out that generation of acoustic cavitation in clinical phacoemulsification and other surgical applications of US is possible. The findings imply that the effects of acoustic cavitation in aqueous medium may contribute to the endothelial damage observed clinically following phacoemulsification cataract surgery. Saturation of the irrigating solution with various gases modifies the acoustic cavitation. Saturation of the irrigating solution with CO2 practically eliminates acoustic cavitation, with the concomitant elimination of radicals and SonL. CO2 may be utilized clinically to suppress acoustic cavitation in phacoemulsification and other medical applications. A cavitation index (CI) is introduced for the purpose of standardizing phacoemulsification instrumentation and other medical US devices that employ HIUE.