Enzymatic studies in foetal brain and liver of mouse following in utero exposure to ultrasound

Lactate, malate and succinate dehydrogenases (LDH, MDH and SDH) were estimated in the foetal brain and liver following in utero exposure of mice to a continuous wave of unfocussed ultrasound. Enzymes in both tissues showed a significant increase (P greater than 0.001), indicating high energy demand due to depletion of oxygen. The increase was recorded even on the twentieth day of pregnancy.     

Physical mechanisms responsible for the relaxation time distribution in disordered dielectrics

The relaxation time distribution function F(τ) is calculated in the framework of the random-field theory. The function F(τ) is expressed through the distribution function f(E) of a random electric field E with due regard for the derived dependence of the relaxation time τ on the electric field. The distribution function F(τ) is calculated in terms of the statistical theory within the random-field approximation. The nonlinear random-field contributions and spatial effects of correlations between randomly distributed electric dipoles are taken into account. The calculations are performed for a mixed ferroelectric glassy phase in which the short-range and long-range polar orders coexist. It is demonstrated that the inclusion of nonlinear contributions of the random field leads to an asymmetric relaxation time distribution function F(τ), whereas allowance made only for the linear random-field contributions results in a symmetric function F(τ). A comparison of the calculated functions F(τ) with empirical functions derived from the Cole-Cole (CC), Davidson-Cole (DC), Kohlrausch-Williams-Watts (KWW), and Havriliak-Negami (HN) laws for the dielectric response shows that these laws correspond to disordered systems in which the long-range and short-range orders coexist. Different forms of the function F(τ) are determined by either linear (the CC law) or nonlinear (the DC, KWW, and HN laws) contributions of the random field.     

Thermal mechanisms responsible for the irreversible degradation of superconductivity in commercial superconductors

Conditions for the irreversible propagation of thermal instabilities in commercial superconductors subjected to intense and soft cooling have been formulated. An analysis has been conducted using two types of the superconductor’s I–V characteristics, i.e., an ideal I–V characteristic, which assumes a step superconducting-to-normal transition, and a continuous I–V characteristic, which is described by a power law. The propagation rate of thermal instabilities along the superconducting composite has been determined. Calculations have been made for both subcritical and supercritical values of the current. It has been shown that they propagate along a commercial superconductor in the form of a switching wave. In rapidly cooled commercial superconductors, the steady-state rate of thermal instability propagation in the longitudinal direction can only be positive because there is no region of steady stabilization. It has been proved that, in the case of thermal instability irreversible propagation, the rise in the commercial superconductor temperature is similar to diffusion processes that occur in explosive chain reactions.     

Treatment of transplanted adriamycin-resistant ovarian cancers in mice by combination of adriamycin and ultrasound exposure

Ovarian cancer models were established in cyclophosphamide immunosuppressed mice by subrenal capsular cell fibrin clot transplantation. SKOV3 cancers were treated by adriamycin alone, or adriamycin combined with ultrasound exposure. SKOV3/ADR cancers were treated with adriamycin, as well as verapamil and insonation were administrated alone or concurrently. The results were: (1) Insonation alone could not suppress growth of tumours. (2) In SKOV3 cancers, ultrasound exposure potentiated the efficiency of adriamycin. (3) In SKOV3/ADR cancers, insonation reversed adriamycin resistance, but verapamil was not effective and no synergism existed between it and ultrasound. These findings revealed that ultrasound exposure enhanced the efficiency of adriamycin to both chemosensitive and chemoresistant ovarian cancers in vivo. Mechanisms were discussed.     

Improvements in azithromycin recrystallization using ultrasound for size reduction

The primary motive of the current work is to achieve smaller mean particle size with narrow size distribution that can enhance the bioavailability of azithromycin (ARZ), an essential requirement due to its poor water solubility. Recrystallization of ARZ was evaluated using cooling as well as antisolvent crystallization approaches in the presence of ultrasonic irradiation with detailed study into effect of different parameters such as ultrasonic power, time and temperature. Ultrasound assisted antisolvent crystallization at low temperatures (<10℃) yielded best size reduction up to 80% with narrower distribution and also gave better yield of the product, that too within 5 min of sonication. With scale up considerations, recirculation mode of operation was also evaluated which offered promising results for the size reduction. Images captured using optical microscope and SEM revealed a nearly uniform rod/plate-shaped geometry. Increase in amorphous nature of ARZ was confirmed based on XRD analysis. FTIR analysis showed no significant changes in the functional groups when compared to the original sample. Overall, the work demonstrated an improved reprocessing approach based on the use of ultrasound with insights into effect of operating parameters and effect of ultrasound on various characteristics.     

FPGA-based architecture for real-time data reduction of ultrasound signals

This paper describes a novel method for on-line real-time data reduction of radiofrequency (RF) ultrasound signals. The approach is based on a field programmable gate array (FPGA) system intended mainly for steel thickness measurements. Ultrasound data reduction is desirable when: (1) direct measurements performed by an operator are not accessible; (2) it is required to store a considerable amount of data; (3) the application requires measuring at very high speeds; and (4) the physical space for the embedded hardware is limited. All the aforementioned scenarios can be present in applications such as pipeline inspection where data reduction is traditionally performed on-line using pipeline inspection gauges (PIG). The method proposed in this work consists of identifying and storing in real-time only the time of occurrence (TOO) and the maximum amplitude of each echo present in a given RF ultrasound signal. The method is tested with a dedicated immersion system where a significant data reduction with an average of 96.5% is achieved.     

Increased accumulation of paclitaxel and doxorubicin in proliferating capillary cells and prostate cancer cells following ultrasound exposure

Introduction

We have previously reported enhanced cytotoxic effects of both doxorubicin and antisense oligonucleotides using an optimized ultrasound regime of a single 10 s exposure in burst-mode (4 MHz, 32 W/cm²(SaTa), 50 ms burst period) in both PC3 (prostate cancer) cells and angiogenic Huvec (human umbilical cord endothelial cells). The objective of this study was to investigate the effect of ultrasound on the cellular uptake of both hydrophilic agents (rhodamine R123, doxorubicin hydrochloride and mannitol) and hydrophobic agents (rhodamine R6G and paclitaxel) using the same 4 MHz ultrasound exposure system.

Methods

PC3 cells and Huvec were incubated with solutions of radioactive or fluorescent compounds for 1 h and ultrasound was then applied to cells. Following washing and lysis of cells, the degree of drug uptake was measured using liquid scintillation counting or fluorescence spectroscopy.

Results

Ultrasound exposure resulted in the enhanced uptake of both hydrophilic and hydrophobic compounds into cells. For paclitaxel, approximately 100% increased uptake was observed when the drug was encapsulated in a nanoparticulate micellar formulation compared to approximately 50% for free drug.

Conclusions

The 4 MHz, 32 W/cm² ultrasound exposure regime (using burst-mode with 50 ms burst period) allows for the enhanced uptake of both water soluble and insoluble compounds into proliferating cancer and angiogenic cells.     

Identification of flow mechanisms for a soft crystal

We study the behavior under flow of soft spherical micelles forming a fcc phase at high volume fraction. Due to the size (300 ?) of the elementary objects, the structure can be investigated through X-rays and neutron scattering, at rest and under flow in a Couette cell. Using scattering in two perpendicular directions, different mechanisms of flow are identified. At intermediate shear (around 100 s^-1) the system exhibits the so called layer sliding mechanism where two dimensional hexagonal compact planes of spheres align themselves with the Couette cell walls. At lower shear rate, the fcc structure is locally preserved, and the flow is mediated by defects between crystallites. At high shear rate, we observe the melting of the structure and a liquid-like structure factor. Moreover, we were able to use the existence of the layer sliding regime to generate a fcc monocrystal by annealing the satcking faults between the decorrelated planes created by the layer sliding. Received: 7 July 1997 / Received in final form: 16 January 1998 / Accepted: 5 March 1998     

Charge redistribution mechanisms of ceria reduction

Charge redistribution at low oxygen vacancy concentrations in ceria have been studied in the framework of the density functional theory. We propose a model to approach the dilute limit using the results of supercell calculations. It allows one to reproduce the characteristic experimentally observed behavior of composition versus oxygen pressure dependency. We show that in the dilute limit the charge redistribution is likely to be driven by a mechanism different from the one involving electron localization on cerium atoms. We demonstrate that it can involve charge localization on light element impurities.     

Speckle reduction for medical ultrasound images with an expectation-maximization framework

In view of inherent speckle noise in medical images,a speckle reduction method was proposed based on an expectation-maximization(EM) framework.First,the real component of the in-phase/quadrature(I/Q) ultrasound image is extracted.Then,it is used to blindly estimate the point spread function(PSF) of the imaging system.Finally,based on the EM framework,an iterative algorithm alternating between the Wiener Filter and the anisotropic diffusion(AD) is exploited to produce despeckled images.The comparison experiment is carried out on both simulated and in vivo ultrasound images.It is shown that,with respect to the I/Q image,the proposed method averagely improves the speckle-signal-to-noise ratio(S-SNR) and the edge preservation index(β) of images by the factor of 1.94 and 7.52.Meanwhile,it averagely reduces the normalized mean-squared error(NMSE) by the factor of 3.95.The simulation and in vivo results indicates that the proposed method has a better overall performance than exited ones.     

Early iNOS impairment and late eNOS enhancement during reperfusion following 2.49 MHz continuous ultrasound exposure after ischemia

ObjectiveIschemia reperfusion (IR) injury, occurring during heart attacks, hemorrhagic shock, and bypass and transplant surgeries, impairs microcirculatory function and nitric oxide (NO) synthesis. We report the regulation of endothelial and inducible NO synthase (eNOS and iNOS) proteins as a consequence of the application of continuous mode diagnostic frequency ultrasound application following IR injury.MethodsAnimals were assigned to one of five groups for microcirculatory assessment or Western blot analysis (WB) as follows: (1) IR+iNOS inhibition (1400W); and (2) IR+1400W+ultrasound for microcirculatory assessment, (3) Control; (4) IR; and (5) IR+ultrasound for WB. Functional capillary density and microvascular diameter, flow velocity, and flow were monitored for microcirculatory assessment. Skin tissue samples were harvested for WB. 2.49 MHz continuous ultrasound was used for application.ResultsBoth the inhibition of iNOS alone and iNOS inhibition with ultrasound irradiation positively influenced the microcirculation of observed animals relative to baseline values. Ultrasound exposure resulted in a significant production of eNOS protein in skin tissue harvested 24 h into reperfusion (p < 0.01). iNOS levels from the same tissue of ultrasound exposed animals were found to be significantly decreased 0.5 h into reperfusion (p < 0.05).ConclusionProtection from lasting IR injury effects in the microcirculation, with continuous mode diagnostic frequency ultrasound, results from augmented eNOS protein levels during late reperfusion. Ultrasound inhibited iNOS protein production during early reperfusion may also confer protection from IR injury.     

Identification of the transition responsible for the visible emission in ZnO using quantum size effects

The emission properties of suspensions of nanocrystalline ZnO particles with different particle sizes were studied. Two emission bands were observed, one being an exciton emission and the other the visible emission of ZnO. The energy of both emissions depends on the particle dimensions due to size quantization. A linear relationship between the energetic maxima of the two emission bands is found. Because of the difference in effective masses of electrons and holes in ZnO, the slope of the linear relationship clearly indicates that the visible emission is due to the transition of an electron from the conduction band to a deep trap. The nature of the deep trap is also considered.     

Fetal development of mice following intrauterine exposure to a static magnetic field of 6.3 T.

The study was undertaken to investigate possible teratogenic effects of a high magnetic field on fetal development in mice. Eighty-four pregnant CD-1 mice (ICR) were exposed to a static magnetic field of 6.3 T for 1 hr a day from day 7 through day 14 of gestation, a period corresponding to major organogenesis. Fifty mice served as controls. Dams were sacrificed on day 18 of gestation. Fetuses were examined for both external and skeletal abnormalities. No significant differences between exposed and control groups were observed regarding litter size, fetal weight, intrauterine mortality rate, or external and skeletal anomalies. The effects of static magnetic field of 6.3 T on the parameters studied appear negligible.     

A new algorithm for detecting fetal heart rate using ultrasound Doppler signals

Although the fetal heart rate monitoring using ultrasound is widely used it is still not optimized for automatic measurements due to the complexity of the Doppler signal. This paper presents a new fetal heart rate (FHR) detecting algorithm, using sampling auto-correlation approach. The results obtained using the custom-built ultrasonic Doppler fetal heart rate monitoring system are presented and confirm the validity of the method.     

Roughness reduction in submicron waveguides by low-molecular weight development

Roughness reduction of a submicron waveguide profile in chemically amplified negative resist is here performed by proper selection of an alkali-based developer, taking into account that its smaller molecules lead to smoother resist surface by altering the developing mechanism of aggregate extraction performed with standard quaternary ammonium hydroxide. Roughness is then analyzed by means of classical Atomic Force Microscope inspection; furthermore, a non-invasive line edge roughness analysis approach based on top-down scanning electron microscope acquisition gives comparable results, in terms of standard deviation and molecular aggregate periodicity.     

Biomolecular absorption of ultrasound. I: Molecular weight

Amino acid solutions have absorptions which are generally small compared to those for proteins. Proteolytic enzyme treatment of proteins in solution reduces their absorption. These observations suggest that absorption increases with molecular weight. However, measurements of sugars, polysaccharides, amino acids, and proteins yield no correlations of absorption with molecular weight within these groups. Therefore, it is concluded that absorption increases in these molecules with increasing molecular weight only in a threshold sense, with absorption increasing significantly only in a restricted molecular weight range. This range may approximate that observed for polyethylene glycol and dextran, viz., 1 to 100 monomer units. However, there is some indication that the transition range may be narrower than a factor of 100 in molecular weight.     

Intrinsic kinetics mechanisms for the catalytic reduction of NO by Na-loaded char

An insight into the interaction between NO and Na-loaded char is essential to improve the catalytic ability of Na to NO reduction, which will be useful to lower NO emissions during thermal utilization of sodium-containing fuels. Here, the intrinsic kinetics mechanisms for the catalytic reduction of NO by Na-loaded char were discussed in details. Using density functional theory (DFT) calculations, possible reaction pathways were first obtained, followed by evaluation of the rate coefficients through transition state theory (TST) calculations. On this basis, the analyses of both sensitivity and rate of products (ROP) were performed to illustrate the intrinsic kinetic mechanism for the NO reduction by Na-loaded char in a certain combustion condition, with an emphasis on the effects of temperature and NO-to-CO stoichiometric ratio. Results indicated that the catalytic active center –ONa plays an important role in the catalytic reduction of NO by Na-loaded char. Specifically, in most cases, the interaction of NO with Na-loaded char largely depends on the elementary reaction of CNO-Na+NO+CO→21-IM3+CO₂. As the stoichiometric ratio of NO to CO increases, the CO-Na+2NO→8-IM4+N₂ becomes increasingly dominant. Moreover, higher temperature causes the CNO-Na+NO→20-P + N₂O as the dominant reaction. Nonetheless, one thing that these reactions have in common is that they are all related to the catalytic active center –ONa. Therefore, the NO reduction Na-loaded char largely depends on the interaction of NO with the carbonaceous surface containing –ONa. Inspired by this, a conceptual approach was proposed to improve the catalytic performance of Na on NO reduction, and it has been shown to be theoretically feasible. To summarize, the combination of DFT, TST and kinetic calculations is useful to clarify the interaction between NO with Na-loaded char, and it gives a basis for the development of micro-kinetic model.     

Postpartum survival of mice exposed in utero to ultrasound

We found no credible enhancement of neonatal mortality in mice exposed in utero on Day 8 of gestation to ultrasound at 0.44 W/cm2 (+/- 20%) spatial average intensity, 2 MHz, continuous wave, for 60--180 s in a 37 degrees C water bath. This result is compared with the adverse effect on neonatal survival reported by Curto [in Ultrasound in Medicine (Plenum, New York, 1976), Vol. 2, pp. 535--536] for exposure on Day 14 of gestation at about 0.125 to 0.5 W/cm2, 1MHz, continuous wave, for 180 s in a 30 degrees C bath. It is concluded that a temporary reduction in fetal viability, lasting from 4 days to less than 10 days after exposure, could account for both sets of data. It is also evident from these data that improved methods of determining intensities within mammalian tissues are highly desirable.     

Use of a silver ion selective electrode to assess mechanisms responsible for biological effects of silver nanoparticles

For a detailed analysis of the biological effects of silver nanoparticles, discrimination between effects related to the nano-scale size of the particles and effects of released silver ions is required. Silver ions are either present in the initial particle dispersion or released by the nanoparticles over time. The aim of this study is to monitor the free silver ion activity {Ag⁺} in the presence of silver nanoparticles using a silver ion selective electrode. Therefore, silver in the form of silver nanoparticles, 4.2 ± 1.4 nm and 2–30 nm in size, or silver nitrate was added to cell culture media in the absence or presence of A549 cells as a model for human type II alveolar epithelial cells. The free silver ion activity measured after the addition of silver nanoparticles was determined by the initial ionic silver content. The p {Ag⁺} values indicated that the cell culture media decrease the free silver ion activity due to binding of silver ions by constituents of the media. In the presence of A549 cells, the free silver ion activity was further reduced. The morphology of A549 cells, cultivated in DME medium containing 9.1% (v/v) FBS, was affected by adding AgNO₃ at concentrations of ≥30 μM after 24 h. In comparison, silver nanoparticles up to a concentration of 200 μM Ag did not affect cellular morphology. Our experiments indicate that the effect of silver nanoparticles is mainly mediated by silver ions. An effect of silver on cellular morphology was observed at p {Ag⁺} ≤ 9.2.     

Degradation and toxicity reduction of textile dyestuff by ultrasound

Degradability of four textile dyes was investigated in deionized water solutions during 520 kHz ultrasonic irradiation. It was found that for all dyes, the rate of color decay was first order in the visible absorption of the dye, and related to the type of functional groups that characterized the chromophore in the dye molecules. The destruction of aromatic/olefinic carbons in azo dyes was slower than that of color--to be attributed to the priority of hydroxyl radical attack on the N=N bonds, and to the formation of numerous oxidation intermediates of organic character during the course of dye degradation. Toxicity analysis of the dye solutions prior to sonolysis revealed that "reactive" dyes were non-toxic, but "basic" ones were toxic at the test concentrations employed in the study. Significant degrees of toxicity reduction were accomplished along with color and aromatic carbon degradation.