Effects of in utero exposure to 4.7 T MR imaging conditions on fetal growth and testicular development in the mouse

The effects of exposure in utero to high field (4.7 T) magnetic resonance imaging (MRI) conditions on fetal growth, adult growth, and testicular development in the mouse were investigated. Exposures of 8-h duration were made on day 9 and/or day 12 of gestation. Also investigated were effects of a combined treatment regime using continuous wave, unfocussed 1 MHz ultrasound on day 9 and MRI on day 12. Treatment groups consisted of 8 to 10 pregnant dams. Fetal data were taken on day 18 of gestation and data from adult animals that were exposed in utero were taken on day 50 postpartum. Significant differences in sensitive biological end points following in utero exposure to complex MRI field conditions were found. Fetal weights of the exposed groups ranged from 11% (day 9 MRI) to 17% (day 9 ultrasound/day 12 MRI) lower (p ≤ .05) than those of the cage control and sham-exposed fetuses and crown-rump length of exposed animals was reduced by 8% (p ≤ .05). The postpartum death rate was as high as 38% (significant at p ≤ .05 level) following MRI exposure on day 9 and day 12 of gestation. Daily sperm production was reduced by as much as 44% (p ≤ .05) in adults exposed to MRI on day 12 of gestation. A reduction in testis weight and volume in the adult males was also seen, but the difference was not statistically significant at the p ≤ .05 level. No effect was seen on embryonic deaths, sex ration, body weight at day 50, spleen weight, or seminal vesicle weight. The mechanism responsible for these results could involve one or more of the applied fields interacting with a sensitive stage of fetal development. Further studies are planned to isolate the individual field components and to elucidate biochemical and/or hormonal changes that may follow in utero exposure.     

Magnetic resonance imaging in obstetrics and gynecology

Magnetic resonance imaging of the female pelvis permits visualization of soft tissue structure previously unseen with other radiological techniques. The internal architecture of the corpus uterus, cervix and vagina are directly visualized in any plane. Furthermore, the hormonal environment of the female can be indirectly determined via assessment of the MR appearance of the uterus. Similarly, the complex changes which occur during pregnancy, such as cervical effacement and the relationship of internal os, fetal part and placenta, are easily documented. MR pelvimetry enables fast, safe depiction of the birth canal. Finally, the demonstrated fetal anatomy may prove particularly useful in the evaluation of intrauterine growth retardation and anomalies indeterminate by ultrasound.     

NMR imaging in human pregnancy: A preliminary study

In an effort to demonstrate the potential of nuclear magnetic resonance imaging (NMR) in the management of pregnancy, 15 patients in the first trimester and one in the third trimester of pregnancy have been investigated in the Aberdeen University NMR imager. Simple measurements of biparietal diameter and crown-rump length were made from both the NMR images and the ultrasound images on the same day, with good correlation between the two. The NMR data was displayed as inversion recovery, calculated T₁, proton density and S₁–S₂ images. The proton density and S₁–S₂ images were found to be the most useful for the demonstration of the fetus and for discriminating between placenta and uterus. The calculated T₁ data provided accurate quantification of the proton-spin lattice relaxation times of the different tissues, indicating that this measurement may be of use in the study of fetal brain development and placental function. The inversion recovery images showed poor tissue discrimination and were found to be of limited value. The unique information available using NMR and the non-invasive nature of the technique indicated that it should provide a useful method for the investigation of both fetal development and placental function in addition to making basic measurements of fetal size.     

On noninvasive assessment of acoustic fields acting on the fetus

The aim of this study is to verify a noninvasive technique for assessing the characteristics of acoustic fields in the audible range arising in the uterus under the action of maternal voice, external sounds, and vibrations. This problem is very important in view of actively developed methods for delivery of external sounds to the uterus: music, maternal voice recordings, sounds from outside the mother’s body, etc., that supposedly support development of the fetus at the prenatal stage psychologically and cognitively. However, the parameters of acoustic signals have been neither measured nor normalized, which may be dangerous for the fetus and hinder actual assessment of their impact on fetal development. The authors show that at frequencies below 1 kHz, acoustic pressure in the uterus may be measured noninvasively using a hydrophone placed in a soft capsule filled with liquid. It was found that the acoustic field at frequencies up to 1 kHz arising in the uterus under the action of an external sound field has amplitude-frequency parameters close to those of the external field; i.e., the external field penetrates the uterus with hardly any difficulty.     

Midgestational exposure of pregnant BALB/c mice to magnetic resonance imaging conditions

The potential for producing reproductive toxicity or teratogenesis in mice by exposure to magnetic resonance imaging (MRI) conditions was evaluated by means of reproduction studies and the homeotic shift test. Embryos from pregnant BALB/c mice were exposed in vivo for 16 hours beginning on gestation day 8.75 to MRI conditions of modest field strength (static field, 0.35 tesla (T); pulsed gradients, 2.3 X 10(-4) T/cm for 2.5 to 10 msec; and radio frequency, 15 MHz at an average of 61.2 mW). Unexposed, sham-exposed (both MRI and X-ray) and X-irradiated (0.5 Gy) animals were the control groups. Neither placental resorptions nor stillbirths were increased by MRI. Fetal weight at birth and crown-rump length were proportional; however, crown-rump length was significantly less (p less than 0.001) in the MRI-exposed fetuses (respective mean values for MRI-exposed fetuses were 21.8 +/- 0.2 mm compared to 22.4 +/- 0.1 for sham-exposed fetuses). Both crown-rump length and fetal weight were significantly reduced after X-irradiation. The percentage of homeotic skeletal shifts was scored for each of eight anatomic sites. Only X-radiation produced significant increases in skeletal shifts. Prolonged midgestational exposure of mice to MRI conditions currently used for human clinical imaging, therefore, failed to reveal overt embryotoxicity (resorptions, stillbirths) or teratogenicity (homeotic shifts), consistent with the non-ionizing properties of MR. However, the slight but significant reduction in fetal crown-rump length after prolonged exposure justifies further study of higher MRI energy levels and consideration of other endpoints for establishing with greater confidence the safety of MRI during pregnancy.     

Novel approach to evaluate the interaction of pulsed ultrasound with embryonic development

An in vitro whole-embryo culture system was used which allowed ultrasound to interact directly with rat embryos, at 9.5 days of gestation, under conditions of controlled temperature. Neural plate damage, expressed during a critical period of forebrain development, was evaluated 48 h post-insonation. Ultrasound-induced effects were thus identified in the absence of significant temperature changes or complications from the influence of maternal physiology. Exposures to 3.2 microseconds pulses of 3.14 MHz ultrasound at a PRF of 2 kHz and 1.2 W cm-2 intensity (ISPTA) for durations of 5, 15 or 30 min produced no major morphological abnormalities at a temperature of 38.5 degrees C. Embryonic response to stress was evidenced by changes in protein synthesis, and delayed development was indicated by a reduction in somite number. These effects were enhanced when the insonation temperature was elevated by 1.5 degrees C.     

Measurements of RF heating during 3.0-T MRI of a pig implanted with deep brain stimulator

Purpose

To present preliminary, in vivo temperature measurements during MRI of a pig implanted with a deep brain stimulation (DBS) system.

Materials and Methods

DBS system (Medtronic Inc., Minneapolis, MN) was implanted in the brain of an anesthetized pig. 3.0-T MRI was performed with a T/R head coil using the low-SAR GRE EPI and IR-prepped GRE sequences (SAR: 0.42 and 0.39 W/kg, respectively), and the high-SAR 4-echo RF spin echo (SAR: 2.9 W/kg). Fluoroptic thermometry was used to directly measure RF-related heating at the DBS electrodes, and at the implantable pulse generator (IPG). For reference the measurements were repeated in the same pig at 1.5 T and, at both field strengths, in a phantom.

Results

At 3.0 T, the maximal temperature elevations at DBS electrodes were 0.46 °C and 2.3 °C, for the low- and high-SAR sequences, respectively. No heating was observed on the implanted IPG during any of the measurements. Measurements of in vivo heating differed from those obtained in the phantom.

Conclusion

The 3.0-T MRI using GRE EPI and IR-prepped GRE sequences resulted in local temperature elevations at DBS electrodes of no more than 0.46 °C. Although no extrapolation should be made to human exams and much further study will be needed, these preliminary data are encouraging for the future use 3.0-T MRI in patients with DBS.     

纳米颗粒DBS/TiO_2的拉曼光谱

采用水热法制得表面包覆有十二烷基苯磺酸的二氧化钛纳米粒子 ,并应用拉曼光谱对其进行了检测。结果表明 :样品为表面包覆有十二烷基苯磺酸的二氧化钛纳米粒子的集合体。其拉曼峰与未包裹的二氧化钛拉曼峰相比 ,出现了蓝移现象 ,从纳米粒子的表面结构及包裹层的压力出发对此现象进行了定性解释和讨论     

纳米颗粒DBS／TiO2的拉曼光谱

采用水热法制得表面包覆有十二烷基苯磺酸的二氧化钛纳米粒子,并应用拉曼光谱对其进行了检测。结果表明：样品为表面包覆有十二烷基苯磺酸的二氧化钛纳米粒子的集合体。其拉曼峰与未包裹的二氧化钛拉曼锋相比,出现了蓝移现象,从纳米粒子的表面结构及包裹层的压力出发对此现象进行了定性解释和讨论。     

DBS包覆TiO2纳米粒子的表面光伏及光致发光性能

采用溶胶-水热法合成了十二烷基苯磺酸钠(DBS)包覆的TiO2纳米粒子,并利用X射线衍射仪、透射电镜、表面光电压谱(SPS)和光致发光光谱(PL)等对样品进行表征.重点探讨了DBS包覆的适宜条件及DBS包覆对TiO2光伏和发光等性质的影响.结果表明,进釜前pH值在4.5~5.5,DBS用量为TiO2质量的1.0%~3.0%时,能够获得理想包覆.在水热过程中,DBS的引入对锐钛矿型TiO2微晶的生长有抑制作用.由于DBS的包覆,使TiO2的SPS和PL信号强度显著下降,这可能与磺酸基的吸电子性以及表面缺陷等的减少有关.     

A technique for evaluating the oil/heavy-oil viscosity changes under ultrasound in a simulated porous medium

Theoretically, Ultrasound method is an economical and environmentally friendly or “green” technology, which has been of interest for more than six decades for the purpose of enhancement of oil/heavy-oil production. However, in spite of many studies, questions about the effective mechanisms causing increase in oil recovery still existed. In addition, the majority of the mechanisms mentioned in the previous studies are theoretical or speculative. One of the changes that could be recognized in the fluid properties is viscosity reduction due to radiation of ultrasound waves. In this study, a technique was developed to investigate directly the effect of ultrasonic waves (different frequencies of 25, 40, 68 kHz and powers of 100, 250, 500 W) on viscosity changes of three types of oil (Paraffin oil, Synthetic oil, and Kerosene) and a Brine sample. The viscosity calculations in the smooth capillary tube were based on the mathematical models developed from the Poiseuille’s equation. The experiments were carried out for uncontrolled and controlled temperature conditions. It was observed that the viscosity of all the liquids was decreased under ultrasound in all the experiments. This reduction was more significant for uncontrolled temperature condition cases. However, the reduction in viscosity under ultrasound was higher for lighter liquids compare to heavier ones. Pressure difference was diminished by decreasing in the fluid viscosity in all the cases which increases fluid flow ability, which in turn aids to higher oil recovery in enhanced oil recovery (EOR) operations. Higher ultrasound power showed higher liquid viscosity reduction in all the cases. Higher ultrasound frequency revealed higher and lower viscosity reduction for uncontrolled and controlled temperature condition experiments, respectively. In other words, the reduction in viscosity was inversely proportional to increasing the frequency in temperature controlled experiments. It was concluded that cavitation, heat generation, and viscosity reduction are three of the promising mechanisms causing increase in oil recovery under ultrasound.     

Effect of ultrasound on sodium arsenate induction time and crystallization property during solution crystallization processes

The effect of ultrasound vibrations on the cooling crystallization of sodium arsenate in supersaturated solutions was investigated. In particular, the effects of ultrasound vibrations on induction time and crystal size distribution were studied using a laser-based apparatus with relative supersaturation ranging from 1.3 to 1.8. The results show that ultrasound vibrations have a significant effect on reducing induction time and crystal size distribution. The application of ultrasound vibrations to the system resulted in a small change in surface tension; however, the induction time and crystal size significantly decreased. The mean size of sodium arsenate crystals decreased from 398.87 ± 3.27 to 168.68 ± 2.07 μm, as the ultrasound power increases from 26 to 130 W. Ultrasound vibrations significantly reduced the induction time in a highly supersaturated solution compared to that in a low supersaturated solution.     

An adaptive squared-distance-weighted interpolation for volume reconstruction in 3D freehand ultrasound

Volume reconstruction is a key procedure in 3D ultrasound imaging. An algorithm named as squared-distance-weighted (SDW) interpolation has been earlier proposed to reduce the blurring effect in the 3D ultrasonic images caused by the conventional distance weighted (DW) interpolation. However, the SDW parameter alpha, which controls the weight distribution, is a constant assigned by operators so that the interpolation effect is invariant for both sharp edges and speckle noises. In this paper, we introduced a new adaptive algorithm based on SDW interpolation for volume reconstruction of 3D freehand ultrasound. In the algorithm, the local statistics of pixels surrounding each voxel grid were used to adaptively adjust the parameter alpha in SDW. The voxel grids with a higher ratio of local variance and mean in their neighbourhoods would have a smaller alpha to make the image details sharper, while the voxel grids locating in regions with a lower ratio of local variance and mean would have a larger alpha to smooth image content in homogeneous regions, where speckle noise is usually observed and damages the image quality. By comparing the simulation results using the SDW and new adaptive algorithm, it was demonstrated that this new algorithm worked well in both edge preservation and speckle reduction.     

Enhancement of the photocatalytic activity of TiO2 nanoparticles by surface-capping DBS groups

TiO₂ nanoparticles capped with sodium dodecylbenzenesulfonate (DBS) are synthesized by a sol-hydrothermal process using tetrabutyl titanate and DBS as raw materials. The effects of surface-capping DBS on the surface photovoltage spectroscopy (SPS), photoluminescence (PL) and photocatalytic performance of TiO₂ nanoparticles are principally investigated together with their relationships. The results show that the surface of TiO₂ nanoparticles can be well capped by DBS groups while the pH value and added DBS amount are controlled at 5.0 and 2% of TiO₂ mass weight, respectively, and the linkage between DBS groups and TiO₂ surfaces is mainly by means of quasi-sulphonate bond. The intensities of SPS and PL spectra of TiO₂ obviously decrease after DBS-capping, while the activity can greatly increase during the photocatalytic degradation of Rhodamine B (RhB) solution, which are mainly attributed to the electron-withdrawing character of the DBS groups. Moreover, the enhancement of photocatalytic activity of DBS-capped TiO₂ is also related to the increase in the capability for adsorbing RhB.     

Ultrasound-assisted regeneration of zeolite/water adsorption pair

The use of ultrasound to enhance the regeneration of zeolite 13X for efficient utilization of thermal energy was investigated as a substitute to conventional heating methods. The effects of ultrasonic power and frequency on the desorption of water from zeolite 13X were analyzed to optimize the desorption efficiency. To determine and justify the effectiveness of incorporating ultrasound from an energy-savings point of view, an approach of constant overall input power of 20 or 25 W was adopted. To measure the extent of the effectiveness of using ultrasound, the ultrasonic-power-to-total power ratios of 0.2, 0.25, 0.4 and 0.5 were investigated and the results compared with those of no-ultrasound (heat only) at the same total power. To analyze the effect of ultrasonic frequency, identical experiments were performed at three nominal ultrasonic frequencies of ~28, 40 and 80 kHz. The experimental results showed that using ultrasound enhances the regeneration of zeolite 13X at all the aforementioned power ratios and frequencies without increasing the total input power. With regard to energy consumption, the highest energy-savings power ratio (0.25) resulted in a 24% reduction in required input energy and with an increase in ultrasonic power, i.e. an increase in acoustic-to-total power ratio, the effectiveness of applying ultrasound decreased drastically. At a power ratio of 0.2, the time required for regeneration was reduced by 23.8% compared to the heat-only process under the same experimental conditions. In terms of ultrasonic frequency, lower frequencies resulted in higher efficiency and energy savings, and it was concluded that the effect of ultrasonic radiation becomes more significant at lower ultrasonic frequencies. The observed inverse proportionality between the frequency and ultrasound-assisted desorption enhancement suggests that acoustic dissipation is not a significant mechanism to enhance mass transfer, but rather other mechanisms must be considered.     

Effects of aging and maternal protein restriction on the muscle fibers morphology and neuromuscular junctions of rats after nutritional recovery

Changes in the nutritional status of mothers may predispose their offspring to neuromuscular disorders in the long term. This study evaluated the effects of maternal protein restriction during pregnancy and lactation on the muscle fibers and neuromuscular junctions (NMJs) of the soleus muscle in the offspring of rats at 365 days of age that had undergone nutritional recovery. Wistar rats were divided into two groups: control (CG) – the offspring of mothers fed a normal protein diet (17%) and restricted (RG) – offspring of mothers fed a low protein diet (6%). After lactation, the male pups received standard chow ad libitum. At 365 days, samples of soleus muscle were collected for muscle fiber analysis (HE staining, NADH-TR reaction and ultrastructure), intramuscular collagen quantification (picrosirius red staining) and NMJs analysis (non-specific esterase technique). The cross-sectional area of type I fibers was reduced by 20% and type IIa fibers by 5% while type IIb fibers increased by 5% in the RG compared to the CG. The percentage of intramuscular collagen was 19% lower in the RG. Disorganization of the myofibrils and Z line was observed, with the presence of clusters of mitochondria in both groups. Regarding the NMJs, in the RG there was a reduction of 10% in the area and 17% in the small diameter and an increase of 7% in the large diameter. The results indicate that the effects of maternal protein restriction on muscle fibers and NMJs seem to be long-lasting and irreversible.     

Application of temperature-controlled ultrasound treatment and its potential to reduce phosphate content in frankfurter-type sausages by 50%

The objective of this study was to evaluate the effect of ultrasound treatments with different durations (15, 20, 25, 30, and 35 min) at a low static temperature (12 °C) controlled by an intelligent temperature control and monitoring system on the quality of 50% reduced-phosphate frankfurters. The results show that without ultrasound treatment, phosphate reduction caused some obvious deficits in the textural properties, sensorial parameters, and oxidative stability of frankfurters. Moreover, 25-min ultrasound treatment could significantly lower the cooking loss and enhance emulsion stability, textural properties, and sensorial parameters of reduced phosphate frankfurters, which was also verified by dynamic water distribution analysis and microstructural observation. Additionally, low constant temperature during ultrasound treatment was another crucial factor in retarding lipid oxidation during storage. Therefore, ultrasound treatment with moderate duration and stable low temperature could be considered a successful approach to obtain healthier reduced-phosphate frankfurters under the “clean label” concept.     

Some regularity on how to locate electrodes for higher fECG SNRs

The electrocardiogram(ECG) recorded from the abdominal surface of a pregnant woman is a composite of maternal ECG, fetal ECG(f ECG) and other noises, while only the f ECG component is always needed by us. With different locations of electrode pairs on the maternal abdominal surface to measure f ECGs, the signal-to-noise ratios(SNRs) of the recorded abdominal ECGs are also correspondingly different. Some regularity on how to locate electrodes to obtain higher f ECG SNRs is needed practically. In this paper, 343 groups of abdominal ECG records were acquired from 78 pregnant women with different electrode pairs locating, and an appropriate extended research database is formed. Then the regularity on f ECG SNRs corresponding to different electrode pairs locating was studied. Based on statistical analysis, it is shown that the f ECG SNRs are significantly higher in certain locations than others. Reasonable explanation is also provided to the statistical result using the theories of the fetal cardiac electrical axis and the signal phase delay.     

Effects of ultrasound on placental transfer during the last third of gestation in the rat

The effect of ultrasound on placental transfer in the rat has been measured in vivo. At 15, 18, 21 and 22 days of gestation one uterine horn of each anaesthetized rat was exposed, after laparatomy, to ultrasound. The control horn was effectively shielded. Radio-labelled tracers were then injected into the maternal circulation via a jugular vein cannula and fetuses removed simultaneously from both experimental and control horns at times predetermined to ensure minimal backflux from fetus to mother. Samples of maternal plasma were also taken at suitable intervals. The radioactive content of fetuses and plasma were measured and a unidirectional materno-fetal clearance value (Kmf) for each fetus calculated. It was shown that in rats whose body temperature was accurately maintained at 37 degrees C, ultrasound at the level used in the present study had no effect on placental clearance. However, in rats whose body temperature was allowed to fall to 32 degrees C, a 3 min exposure to 1.1 MHz continuous wave ultrasound at 1 W cm-2 caused a significant (p less than 0.001) decrease in the placental clearance of 22Na (by 55%) and 51Cr-EDTA (by 45%) in rats at 15 days of gestation. These effects showed no dose response and were not observed in rats at any of the other stages of gestation which we investigated. However, in rats at 21 days of gestation the clearance of 45Ca2+ was significantly (p less than 0.01) reduced (by 30%) by a similar exposure to ultrasound. It is concluded that although an interesting biological effect of ultrasound at low body temperatures has been observed, it has little relevance for the normal use of ultrasound in obstetrics.     

Sensitization effects of supramolecular assemblies on the luminescence of terbium-ion prulifloxacin complexes

Luminescence enhancement of terbium-ion prulifloxacin complexes (Tb(III)-PUFX) in supramolecular hydrogels formed by assembly of 1,3:2,4-di-O-benzylidene-D-sorbitol (DBS) was investigated by steady-state fluorescence, varying temperature fluorescence and time-resolved fluorescence. The luminescence images show that Tb(III)-PUFX were dispersed in the DBS gels. The luminescence intensity of Tb(III)-PUFX in the DBS gels was significantly increased in comparison with that in corresponding aqueous solutions. The varying temperature fluorescent spectra show that the luminescence intensity of Tb(III)-PUFX decreased with an increase in the temperature. This implies that the luminescence enhancement of Tb(III)-PUFX is related to the dissociation and the formation of the DBS assemblies. Time-resolved fluorescence measurements show slower rotational motion in DBS gels in comparison with that in the corresponding aqueous solutions. This may be ascribed to a unique microstructure of three-dimensional network formed by DBC aggregates, resulting in deactivation of the nonradiative relaxation. The images of field emission scanning electron microscopy and polarized optical microscopy indicate that the morphology of the DBS assemblies was not influenced upon addition of Tb(III)-PUFX to the DBS gels.