The immediate reproducibility of T wave alternans during bicycle exercise

A number of recent studies have demonstrated that the microvolt level T wave alternans measured during bicycle exercise can identify patients at high risk for developing malignant ventricular arrhythmias. However, little is known about the reproducibility of T wave alternans measured during bicycle exercise. The purpose of this study was to prospectively evaluate the immediate reproducibility of T wave alternans measured during bicycle exercise testing. Thirty-five patients with congestive heart failure underwent two sequential bicycle exercise tests with the measurement of T wave alternans. The T wave alternans tests were randomly sorted and then classified by two readers who were blinded to the patient and the sequence of the two tests. Tests were classified as determinate (positive or negative) or indeterminate according to previously published criteria. Of the 22 patients that had two determinate T wave alternans tests, 18 (82%) of 22 patients had concordant test results (kappa 0.58). Of the four patients who had discordant test results on the two tests, three patients had one test that was borderline and difficult to interpret. One patient had two sequential tests that were clearly different. Of the ten patients whose initial test was indeterminate, five became determinate on the second test. T wave alternans measured during bicycle exercise has an acceptable reproducibility when measurements are madefrom two sequential exercise tests performed within a short period. This data suggests that the measurement of T wave alternans during exercise is reliable. Repeating the exercise test with a second measure of T wave alternans during the same session can significantly reduce the proportion of patients with indeterminate test results.     

On-line noninvasive one-point measurements of pulse wave velocity

 Pulse wave velocity (PWV) is a basic parameter in the dynamics of pressure and flow waves traveling in arteries. Conventional on-line methods of measuring PWV have mainly been based on “two-point” measurements, i.e., measurements of the time of travel of the wave over a known distance. This paper describes two methods by which on-line “one-point” measurements can be made, and compares the results obtained by the two methods. The principle of one method is to measure blood pressure and velocity at a point, and use the water-hammer equation for forward traveling waves. The principle of the other method is to derive PWV from the stiffness parameter of the artery. Both methods were realized by using an ultrasonic system which we specially developed for noninvasive measurements of wave intensity. We applied the methods to the common carotid artery in 13 normal humans. The regression line of the PWV (m/s) obtained by the former method on the PWV (m/s) obtained by the latter method was y = 1.03x − 0.899 (R ² = 0.83). Although regional PWV in the human carotid artery has not been reported so far, the correlation between the PWVs obtained by the present two methods was so high that we are convinced of the validity of these methods. Received: May 13, 2002 / Accepted: August 2, 2002 Acknowledgment This work was partly supported by a Grant-in-Aid for Scientific Research (B) 14380414 from the Ministry of Education, Culture, Sports, Science and Technology of Japan, and by Research and Development Committee Program of the Japan Society of Ultrasonics in Medicine. Correspondence to A. Harada     

骨髓间充质干细胞移植对大鼠钙化主动脉结构及顺应性的影响

目的研究骨髓间充质干细胞对大鼠大血管钙化是否具有修复作用。方法选用8周龄健康Wister鼠复制维生素D 尼古丁钙化模型,采用左心室直接注射干细胞的方法进行干预移植,4周后检测有创血压、脉搏波传导速度,评价动脉顺应性;采用不同染色方法分析组织中弹性纤维、胶原纤维比例,动脉壁中Ⅰ、Ⅲ型胶原的水平和比例变化及动脉钙化程度;采用原子吸收光谱法测定钙化组织中钙含量。结果维生素D 尼古丁钙化大鼠接受骨髓间充质干细胞干预后弹力/胶原纤维比值发生改变,细胞移植组高于假移植组(1.5%±0.3%比0.9%±0.2%,P<0.01)。骨髓间充质干细胞移植组弹力纤维保持固有形状,与胶原纤维结合紧密;动脉组织局部钙含量较假移植组下降(13.80±1.28mg/g比29.90±1.85mg/g,P<0.01)。上述动脉结构的改变伴有动脉顺应性的改善。结论骨髓间充质干细胞移植能改善细胞外基质成分的构成比例,部分抑制钙在动脉壁中的沉积过程,这种动脉结构的恢复伴有动脉顺应性的改善。     

A new teaching model of the systemic circulation that incorporates reservoir characteristics

A hydraulic teaching model of the human systemic circulation is proposed, based on the principles of the reservoir-wave approach. Reservoir characteristics are portrayed by the arterial tall-and-narrow and venous short-and-wide columns, the relative compliances of which are signified by their diameters. Wave characteristics are represented by proximal arterial and venous resistances; rapid left ventricular ejection and rapid right atrial filling cause flow-dependent pressure drops across the respective resistances. (The value of the proximal arterial resistance is numerically equal to the characteristic impedance.) The pressure drop across the proximal arterial resistance, excess pressure, is understood to be fundamentally wave-related and has been shown to be a measure of the efficiency of cardiac-vascular coupling. Excess pressure also predicts an incremental risk of cardiovascular morbidity and largely accounts for the hysteresis evidenced by an open aortic pressure-volume loop.     

Bone Marrow Edema Syndrome of the Medial Femoral Condyle Treated With Extracorporeal Shock Wave Therapy: A Clinical and MRI Retrospective Comparative Study

Objective

To determine the validity of extracorporeal shock wave therapy (ESWT) in the treatment of bone marrow edema (BME) of the medial condyle of the knee.

Estimating acoustic peak pressure generated by ultrasound transducers from harmonic distortion level measurement

Pressure amplitude measurement is important for general research on ultrasound. Because it requires high accuracy, it is usually done using a hydrophone calibrated by an accredited laboratory. In this paper, a method is proposed for estimating the pressure amplitude in the ultrasound field using an uncalibrated single-element transducer and Khokhlov-Zabolotskaya-Kuznetsov simulations of the ultrasound field. The accuracy of the method is shown to be better than 20% for slightly focused and nonfocused transducers. Extending the method to a pulse-echo setup enables pressure measurement of a transducer without the need for an extra transducer or hydrophone.     

New avian suspension cell lines provide production of influenza virus and MVA in serum-free media: Studies on growth,metabolism and virus propagation

Few suspension cells can be used for vaccine manufacturing today as they either do not meet requirements from health regulatory authorities or do not produce high virus titres. Two new avian designer cell lines (AGE1.CR and AGE1.CR.pIX) that have been adapted to grow in suspension in serum-free medium were evaluated for their potential as host cells for influenza and modified vaccinia Ankara (MVA, wild type) vaccine production. Their metabolism was studied during growth in static (T-flasks) and dynamic cultivation systems (roller bottles, stirred tank reactor, wave bioreactor). High cell concentrations up to 5.8 × 10⁶ cells/mL were obtained with doubling times of 23 h for AGE1.CR and 35 h for AGE1.CR.pIX, respectively. Both viruses were produced to high titres (3.5 log HA/100 μL for influenza virus, 3.2 × 10⁸ pfu/mL for MVA). Hence, the CR cell lines are an appropriate substrate for pharmaceutical influenza and MVA production.     

波强的研究和应用进展

波强（WI）是关于波的传导的血流动力学指数,WI测量方法是在传统eTRACKING技术基础上发展的一项实时测量系统,该方法利用内径一压力的线性关系提供心脏和血管系统的血流动力学表现及相互关系。本文对WI研究进展及其在实验室和临床科研中的应用进行综述。