细胞凋亡在子宫肌瘤组织射频治疗中的作用

目的研究细胞凋亡在子宫肌瘤组织射频治疗中的作用。方法光镜和电镜检测多电极射频消融的子宫肌瘤组织及未消融的子宫肌瘤组织中的凋亡细胞。用免疫组化二步法检测20例多电极射频消融的子宫肌瘤组织及未消融的子宫肌瘤组织中Bc l-2(B cell lymhpom a/leukem ia-2)和Bax(Bc l-2 assoc iated x-prote in)蛋白的表达。结果在消融灶边缘及其外0.5 cm的子宫肌瘤组织,细胞凋亡指数(16.3±3.4)高于未消融的子宫肌瘤组织(7.1±1.6,P<0.01);同时Bc l-2蛋白表达减弱(P<0.05),Bax蛋白表达增强(P<0.05)。结论高温诱导的细胞凋亡在射频消融致子宫肌瘤治疗中起着相关作用,可能是消融引起肌瘤坏死的机制之一。     

Analysis of temperature measurement for monitoring radio-frequency brain lesioning

During ablative neurosurgery of movement disorders, for instance therapy of Parkinson's disease, temperature monitoring is crucial. This study aims at a quantitative comparison of measurement deviations between the maximum temperature located outside the lesioning electrode and two possible thermocouple locations inside the electrode. In order to obtain the detailed temperature field necessary for the analysis, four finite element models associated with different surroundings and with different power supplies are studied. The results from the simulations show that both the power level and the power density as well as the surrounding medium affect the temperature measurement and the temperature field in general. Since the maximum temperature is located outside the electrode there will always be a deviation in time and level between the measured and the maximum temperature. The deviation is usually 2–7 s and 3–12°C, depending on, for example, the thermocouple location and surrounding medium. Therefore, not only the measured temperature but also the relation between measured and maximum temperature must be accounted for during therapy and device design.     

Use of diaphragm transducers in the measurement of pressures on soft materials

Diaphragm pressure transducers are designed to measure pressures in fluids, but have also been applied to measuring pressures on soft materials, such as at the interface between the residual limb of a lower-limb amputee and the supporting surface defined by the prosthetic socket. The reliability and accuracy of Kulite^TM XTM-190 transducer as a pressure monitor on soft materials, such as silicone and Pelite^TM was evaluated in three physical model set-ups. The evaluations included the uniform loading of solid disks of silicone and Pelite^TM, the application of air pressure to the core of a contained thick-walled cylinder made of silicone, and the dynamic indentation of a contained solid silicone cylinder. Sensor measurements in all situations were similar to analytical, iterative or finite element solutions when certain conditions were met. These conditions include: (i) lubricating the interface between the soft material and the supporting structure; (ii) calibrating the transducers under surface and material conditions used during measurements; and (iii) using compatible soft materials (e.g. silicone but not Pelite^TM).     

Automating inventorying of blood stations: A system based on ultrahigh-frequency radio-frequency identification (UHF RFID) technology

Inventorying blood products is an essential process in blood station management. Traditional methods need to integrate barcodes with refrigerators, which suffer from low time efficiency, high error rate and high labour cost. Several methods have been proposed to automate this process in blood stations. However, none of them is ideal enough. In this paper, we analyse the difficulties of automation in blood inventory, and propose an automated blood inventory system based on UHF RFID technology. Comparisons over our method with manual inventory and handheld RFID inventory are conducted. The result shows that our method is nearly 10 times higher than manual inventory in time efficiency while increases the accuracy to 100%.     

Characterization of bone materials as ultrasonic transducers

Physical, dielectric, piezoelectric and electromechanical parameters have been reported for bone and its two major constituents i.e. collagen and apatite, for their characterization as ultrasonic transducer materials. Collagen and apatite have been extracted from full bone using well known methods. These materials have been used to prepare simple disc-shaped test pieces (dimensions: diameter 10 mm and thickness 1.0 ± 0.01 mm). The variation of various electrical parameters with frequency in the region (1–108 MHz) is examined for these materials. These include impedance, phase angle, relative voltage output, quality factor ‘Q’, dielectric constant and resistivity. The data so obtained are compared with those for ceramic and quartz transducers. The observations on impedance, phase and relative voltage output for bone materials indicate that the first resonance peak falls around 56 MHz followed by second and third harmonics around 112 MHz and 168 MHz respectively. A low ‘Q’ value suggests a fairly wide band transducer, while other parameters compare favourably with ceramic and quartz materials. Bone material has also been used to obtain a transducer in the standard configuration and velocity dispersion in the frequency range 1–108 MHz is examined.     

Possible use of mechanical-to-electrical transducers in experimental biological research

Mechanical-to-electrical transducers (mechanotrons), used in engineering to measure displacement, forces, pressures, and other mechanical parameters, were tested as sensitive elements for recording contractile activity of isolated objects (the frog ventricle, a segment of rat ileum), and also the level of the arterial pressure in anesthetized animals. The results showed that mechanotrons are simple, convenient, and reliable instruments for such investigations.Department of Pharmacology, Faculties of Internal Medicine and Hygiene, I. M. Sechenov First Moscow Medical Institute. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 11, pp. 626–629, November, 1979.     

Simulation of a programmable pulser for phased array transducers

We propose circuits for the implementation of a programmable pulser for phase array transducers. These provide digital control of pulse timing and firing, plus the possibility of manual setting of exciting pulse nature (simple or double), width and amplitude. Matching to the probe is thus optimized while programming enables adaptation to various types of transducers.     

Analysis of the dynamic characteristics of pressure transducers for studying respiratory mechanics at high frequencies

Differential pressure transducers are commonly used to study respiratory mechanics at physiological frequencies as well as during external forcing at high frequencies. In the latter condition, measuring errors could occur if the input impedance of the pressure transducers is not sufficiently large with respect to that of the respiratory system. In this work we analysed the input impedance Z and the transfer function H of two common pressure transducers (Validyne MP-45 and Celesco LCVR) equipped with membranes of different sensitivities and with connecting tubes of different lengths. Z was measured by the tube method and H was measured by comparison with a flat-response pressure transducer. In agreement with the predictions based on a simple lumped-parameters model, we found that Z reached very low values, especially at the frequencies where H had a resonance peak. For instance, for the widespread Validyne MP-45 transducer (200 Pa) with connecting tubes of 16 cm length and 3·8 mm internal diameter a minimum of Z of 8300 Pa s litre⁻¹ at 96 Hz was measured; at that frequency the amplitude of H attained a value of 3·1. Using the above transducer model we simulated the measurement of a rat input impedance up to 128 Hz using Validyne and Celesco transducers. With the Validyne MP-45 (200 Pa), equipped with the same connecting tubes as above, the computed error reached up to 50 per cent for the real part and 140 per cent for the imaginary part.     

Investigating a compact phantom and setup for testing body sound transducers

Contact transducers are a key element in experiments involving body sounds. The characteristics of these devices are often not known with accuracy. There are no standardized calibration setups or procedures for testing these sensors. This study investigated the characteristics of a new computer-controlled sound source phantom for testing sensors. Results suggested that sensors with different sizes require special phantom requirements. The effectiveness of certain approaches on increasing the spatial and spectral uniformity of the phantom surface signal was studied. Non-uniformities >20 dB were removable, which can be particularly helpful in comparing the characteristics of different size sensors more accurately.     

Ring electrode for radio-frequency heating of the cornea: Modelling and<Emphasis Type="Italic">in vitro</Emphasis> experiments

Radio-frequency thermokeratoplasty (RF-TKP) is a technique used to reshape the cornea curvature by means of thermal lesions using radio-frequency currents. This curvature change allows refractive disorders such as hyperopia to be corrected. A new electrode with ring geometry is proposed for RF-TKP. It was designed to create a single thermal lesion with a full-circle shape. Finite element models were developed, and the temperature distributions in the cornea were analysed for different ring electrode characteristics. The computer results indicated that the maximum temperature in the cornea was located in the vicinity of the ring electrode outer perimeter, and that the lesions had a semi-torus shape. The results also indicated that the electrode thickness, electrode radius and electrode thermal conductivity had a significant influence on the temperature distributions. In addition,in vitro experiments were performed on rabbit eyes. At 5 W power, the lesions were fully circular. Some lesions showed non-uniform characteristics along their circular path. Lesion depth depended on heating duration (60% of corneal thickness for 20s, and 30% for 10s). The results suggest that the critical shrinkage temperature (55–63°C) was reached at the central stroma and along the entire circular path in all the cases.     

小鼠STAT4和STAT6基因酵母双杂交表达载体的构建与鉴定

目的:分别克隆小鼠信号传导和转录活化因子-4(STAT4)、信号传导和转录活化因子-6(STAT6)基因编码序列(CDS序列),构建并鉴定其酵母表达质粒pGADT7-STAT4和pGADT7-STAT6。方法:PCR扩增STAT4和STAT6基因CDS序列,T-A亚克隆到pMD19-T simple载体中,酶切获取目的基因STAT4和STAT6,克隆入已经过双酶切和CIAP脱磷酸处理的酵母表达载体pGADT7,酶切鉴定并测序;转化pGADT7-STAT4和pGADT7-STAT6到酵母AH109细胞中,Western blot分析STAT4和STAT6的蛋白表达情况,同时检测其毒性和自激活作用。结果:成功扩增了STAT4和STAT6基因CDS序列,并分别成功克隆到pMD19-T simple载体和pGADT7中,测序结果符合要求。酵母表达质粒pGADT7-STAT4和pGADT7-STAT6成功转化到酵母AH109细胞中,无毒性和自激活作用,Western blot结果证实酵母细胞高表达融合蛋白STAT4和STAT6。结论:成功构建了酵母表达质粒pGADT7-STAT4和pGADT7-STAT6,为进一步研究STAT4和STAT6蛋白与其他蛋白质的相互作用奠定了基础。     

信号转导及转录激活因子家族分子在巨噬细胞极化调控中的作用研究进展

巨噬细胞在调控炎症及免疫反应,维持免疫稳态中发挥关键的作用.不同微环境条件下,巨噬细胞功能出现异质性.其可以极化为经典活化(M1)或替代活化(M2)两种不同的极化类型,分别发挥促炎或抑炎的功能.众所周知,许多调控分子参与了巨噬细胞的极化调控过程.在众多的极化调控分子中,信号转导及转录激活因子(Stats)家族是一类最主要的调控分子.Stats家族有7个成员,即Stat1、Stat2、Stat3、Stat4、Stat5a、Stat5b和Stat6.它们结构相似,但功能不同.目前已经明确,Stats分子在机体炎症应答中发挥重要的作用,调控着巨噬细胞的极化进程.     

Radio frequency perforation of cardiac tissue: Modelling and experimental results

Radio frequency (RF) current delivered through a thin catheter can be used to perforate the pulmonary valve or the atrial septum to treat pulmonary atresia in newborns. To understand better the mechanisms of RF perforation, a numerical model is developed, and experiments are performed in isolated canine cardiac tissue. The model consists of a cylindrical domain with a tissue layer between two blood layers. The finite-difference method is used to compute both the potential and temperature distributions. When the tissue temperature exceeds 100°C in all points that are directly in front of the catheter, these points are considered to be instantly vaporised, and the catheter advances over these points. The computed temperature time course coincides with measured temperature at small voltages (<16 V). Simulated perforation occurs when the voltage exceeds a threshold of 70–80V for a catheter diameter of 0.30–0.44 mm, which coincides with experimental observations in the myocardium. A voltage exceeding this perforation threshold tends to decrease tissue damage. Shorter electrodes (0.7 mm as against 2.4 mm) with smaller diameters produce a more rapid perforation. In conclusion, numerical simulations provide insights into aspects of RF perforation, such as electrode size, current, speed of perforation and collateral damage.     

Application of air-borne ultrasound to biomedical measurements

Remote measurement of distance, direction, size, form and volume are common but intricate measurement problems. We have applied the ultrasound pulse echo method, well-known from diagnostic ultrasound, for remote measurement in air. Short ultrasound pulses are emitted in air by electric excitation of an ultrasound transducer. When the ultrasonic wave is incident on a boundary between media of different acoustic impedance, part is reflected back as an echo. The time delay between transmission of the ultrasound pulse and the reception of an echo is a measure of the distance between the transducer and the echo-generating structure. The information obtained can be processed in different ways to produce the three main types of display: A-mode, B-mode and TM-mode. As a consequence most methods from diagnostic ultrasound can be applied also for ultrasound in air. Examples are given of biomedical applications, including a real-time ultrasound scanner for use in air.     

Linearity and frequency response of fleisch type pneumotachometers

Some aspects of the linearity and the frequency response of flow measurement with Fleisch type pneumotachometers are considered. The transition from a uniform velocity distribution at the entrance of the capillary tubes of the transducer to a fully developed flow profile is discussed as one of the phenomena influencing the linearity of the set-up.Besides, an expression is derived for the frequency response of the Fleisch pneumotachometer. The frequency responses as derived from measurements show good agreement with theory. In the range of the lower frequencies the frequency response of the flow measuring set-up is proved to be largely determined by the frequency response of the pressure transducer with the connecting tubes. A simple way is indicated to measure the latter. This, in combination with the calculated frequency response of the flow transducer, makes it fairly casy to determine the frequency response characteristics of a flow measuring set-up containing a Fleisch type pneumotachometer.