7-甲氧基-4′-羟基-3′-二乙胺甲基异黄酮(MHDF)对大鼠血流动力学和主动脉的作用

本实验观察了MHDF对整体大鼠血流动力学和离体大鼠胸主动脉的作用。结果表明iv MHDF(3～12.8 mg/kg)能降低大鼠左心室±dp/dt_max,V_max,V_pm和LVSP,延长T-dp/dt_max,减慢心率。MHDF还能舒张大鼠胸主动脉,ED₅₀为6.5×10^-6mol/L;非竞争拮抗NA和CaCl₂致主脉收缩,pD₂′为3.11±0.21和3.73±0.07;抑制高K⁺致主动脉收缩,IC₅₀为1.76×10^-5mol/L。提示MHDF对血管的作用与α受体阻断剂不同,而可能与钙拮抗有关。     

The quitting experience for smokers in sixth through twelfth grades

The present study examined the withdrawal process for adolescents who had attempted to quit smoking. A sample of 622 6th through 12th graders were interviewed. Smoking status was reported prior to attempting to quit and its relationship with the withdrawal experience was evaluated. Although over half of those who smoked regularly reported trying to quit, 78% of the "quitters" were smoking six months after their quit attempt. Experiencing adverse withdrawal symptoms was related to smoking at daily levels before quitting; delaying trying to quit was associated with initiation of smoking at an early age; and quitting success was predicted by early quitting age, lower pre-quitting smoking levels, a lack of a prior quitting failure, and peer smoking. The results suggest that smoking intervention programs for adolescents should include components facilitating the quitting process that take into consideration youngsters' smoking and quitting histories.     

A Field-Compatible Method for Interpolating Biopotentials

Mapping of bioelectric potentials over a given surface (e.g., the torso surface, the scalp) often requires interpolation of potentials into regions of missing data. Existing interpolation methods introduce significant errors when interpolating into large regions of high potential gradients, due mostly to their incompatibility with the properties of the three-dimensional (3D) potential field. In this paper, an interpolation method, inverse-forward (IF) interpolation, was developed to be consistent with Laplace's equation that governs the 3D field in the volume conductor bounded by the mapped surface. This method is evaluated in an experimental heart–torso preparation in the context of electrocardiographic body surface potential mapping. Results demonstrate that IF interpolation is able to recreate major potential features such as a potential minimum and high potential gradients within a large region of missing data. Other commonly used interpolation methods failed to reconstruct major potential features or preserve high potential gradients. An example of IF interpolation with patient data is provided to illustrate its applicability in the actual clinical setting. Application of IF interpolation in the context of noninvasive reconstruction of epicardial potentials (the inverse problem) is also examined. © 1998 Biomedical Engineering Society. PAC98: 8710+e, 0260Ed     

Beckman EL-ISE电解质分析仪准确性及故障的分析判断

0 引言为了克服离子选择电极（ISE）法的微量电位信号极易受环境温度变化及电子噪声的干扰问题,该仪器采用了参考电极,把参考电极与其测定电极装在同一测量室内,保持其相同的物理环境,使干扰源对所有电极的影响相同. 以内参液作为参考电极的测量对象,测得一个参考电极电位值,再测样品的电极电位值,二者相抵就消除了所叠加的干扰信号.     

心脏直视手术围术期自体血回输335例的监护

0　引言　自体输血是采集患者体内血或回收自体失血,再输回同一患者,献血者与受血者为同一个体,既可以节约临床用血,减少患者费用,更重要是可以避免或减少同种输血传播感染性疾病.我科对335例体外循环心内直视手术患者实行自体血回输,收到较好的社会效益和经济效益.1　临床资料　1998-09/1999-02,我科心脏直视手术共445例,围术期采用自体输血335例,其中先心病226例,瓣膜手术59例,复杂心内畸形37例,冠心病、大血管13例,占同期体外循环心内直视手术75%.患者主要适应证:心脏及大血管外科手术,术前一般情况尚好,无肝、肾、呼吸功能障碍;术前检查…     

Determination of transmural location of onset of activation from cardiac surface electrograms

Methods of estimating depth of origin of ventricular activation from cardiac surface electrograms were evaluated in experiments on eight dogs. The ventricles were paced via multielectrode needle arrays placed transmurally in from four to six locations in the wall of the left ventricle. A multiplexed data-recording system was used to simultaneously record from 64 unipolar cardiac surface electrodes during pacing at each multielectrode needle site. The four indexes evaluated were the maximum and average gradients of activation isochrones around the site of earliest epicardial activation, the QRS area at the site of earliest epicardial activation, the interval between the QRS onset computed from all 64 epicardial surface electrograms, and the time of the minimum dV/dt in the electrogram displaying the earliest epicardial activation time (t(ee)-t(rmso) interval). Correlation coefficients between depth of stimulation and average and maximum gradients of isochrones, QRS area at the site of earliest epicardial activation, and t(ee)-t(rmso) interval were 0.985 or higher. These methods, particularly those involving gradients of isochrones, should be useful for evaluating electromaps of patients undergoing surgery for ablation of tachyarrhythmias.     

Biological Interactions of Aging and Anemia: A Focus on Cytokines

Anemia is one of the characteristics of the frailty phenotype and is often observed in elderly patients. Although anemia in people of advancing age can often be attributed to underlying etiologies such as iron deficiency or chronic disease, some cases do not have any identifiable cause. Therefore, it has been suggested that the aging process itself might be an intrinsic factor in the development of anemia, possibly through the age-related dysregulation of certain proinflammatory cytokines such as interleukin-6 (IL-6). Although the mechanism underlying the association between increased IL-6 and anemia has not been fully elucidated, it has been suggested that, like with other cytokines, it involves direct inhibition of erythropoietin production or interaction with the erythropoietin receptor.