微波消融犬室性心动过速的实验研究

观察微波消融犬室性心动过速（简称室速）疗效和微波消融对血液动力学的影响。健康犬４０只,随机分成５组,Ⅰ组（对照组,ｎ＝８）,Ⅱ、Ⅲ、Ⅳ和Ⅴ组（消融组,ｎ＝８）,由股动脉、股静脉穿刺进行血液动力学监测。用０．０１ｍｌ０．０３％乌头碱注入心室壁诱发室性心动过速。消融释放功率和时间Ⅱ组为４０Ｗ×３０ｓ,Ⅲ组为４０Ｗ×６０ｓ,Ⅳ组为８０Ｗ×３０ｓ,Ⅴ组为８０Ｗ×６０ｓ。结果：自发放微波能量至室速终止时间Ⅱ、Ⅲ组为（１０．１±２．４）ｓ,与对照组比,Ｐ＜０．００１;Ⅳ、Ⅴ组为（５．３±１．５）ｓ,与对照组比,Ｐ＜０．００１。消融前后血液动力学各项指标差异无统计学意义（Ｐ＞０．０５）,消融后组间血液动力学各项指标差异无统计学意义（Ｐ＞０．０５）。微波产生的心肌损伤,显微镜下观察均为凝固性坏死,与周围组织存在清晰的界限。结论：微波消融室速具有较好的疗效,消融能量与时间在一定范围内对血液动力学无明显影响,可望成为室速治疗的１种新方法。     

Radiofrequency ablation in children

Radiofrequency (RF) catheter ablation has ushered in a new era in the management of patients with symptomatic tachyarrhythmias. By providing the ability to cure the underlying arrhythmic substrate, RF catheter ablation obviates the need for life-long antiarrhythmic drugs. In the reported series, the success has been high and the complications have been infrequent and relatively minor. Not unexpectedly, RF catheter ablation has become the treatment of choice for patients with symptomatic paroxysmal tachyarrhythmias. The role of radiofrequency catheter ablation in infants and small children remains controversial, and awaits a larger experience and longer follow-up data.     

Fascicular tachycardia sensitive to calcium antagonists

Five patients with recurrent tachycardias exhibiting right bundlebranch block with left axis deviation were referred for investigation.In each case, a supraventricular mechanism was suspected. Duringsinus rhythm, the QRS morphology and axis (–10 to +60degrees) and HV intervals were normal. Tachycardia was initiatedby timed ventricular premature stimuli in 4 patients, rapidventricular pacing in 3 patients and rapid atrial pacing in2 patients. The tachycardia cycle length varied from 275 to380 ms with right bundle branch block and a leftward axis changeof 30 to 125 degrees at the onset of the tachycardia. The HVinterval ranged from +15 to –20 ms. In each patient ventriculoatrialdissociation occurred spontaneously or could be induced. Alltachycardias could be terminated or greatly slowed by calciumantagonists. These data are consistent with an unusual reentrantmechanism of tachycardia located in the posterior fascicle ofthe left bundle branch.     

Effects of DPI 201-106, a novel cardiotonic agent,on hemodynamics,cardiac electrophysiology and arrhythmias induced by programmed ventricular stimulation in dogs with subacute myocardial infarction: A comparative study with dobutamine

Summary DPI 201-106 (DPI), a novel and potent cardiotonic agent, exhibits its effects by prolonging the open state of Na⁺ channels, resulting in an increase in action potential duration, and thus, is supposed to share the class III antiarrhythmic activity. The effects of DPI on the hemodynamics, intraventricular conduction and refractoriness of heart, and the incidence of arrhythmias induced by programmed electrical ventricular stimulation (PES) were compared with (±)-dobutamine. Dogs which survived for 5 to 7 days after the induction of myocardial infarction were used as the model. The presence of sub-acute myocardial infarction caused by occluding the left anterior descending coronary artery elicited a mild left ventricular dysfunction represented by a significant decrease in peak LV dp/dt by about 20%.Both i.v. bolus injection of DPI (1, 3 and 5 mg/kg) and i. v. continuous infusion of dobutamine (3, 5 and 10 g/kg/min), which were administered in a cumulative manner, dose-dependently improved the hemodynamic parameters. At the higher doses of both DPI (3 and 5 mg/kg) and dobutamine (5 and 10 g/kg/min) the control values were reached or even exceeded. DPI dose-dependently increased the effective refractory period (ERP) of both non-infarcted and infarcted ventricular myocardia to a similar degree, but the conduction time showed a frequency-dependent increase in the infarcted myocardium to a greater degree than in the non-infarcted myocardium after DPI. In contrast, dobutamine decreased the ERP in both non-infarcted and infarcted myocardia, and slightly increased the difference of refractoriness between the non-infarcted and infarcted zones with no effect on the intraventricular conduction. In the PES study, DPI (3 and 5 mg/kg) produced a significant decrease in the incidence of ventricular tachycardia, whereas dobutamine (5 and 10 g/kg/min) tended to worsen the arrhythmias. These findings suggest that cardiotonic agents with a class III antiarrhythmic property such as DPI may be potentially useful for the management of heart failure accompanied by ischemic heart disease.Abbreviations DPI, DPI 201-106; PES programmed electrical ventricular stimulation - LV dp/dt the rate of rise of left ventricular pressure - ERP effective refractory period - RVOT right ventricular outflow tract - VT ventricular tachycardia - LAD left anterior discending coronary artery Send offprint requests to T. Uematsu at the above address     

Pharmacological comparison of the sigma recognition site labelled by [3H]haloperidol in human and rat cerebellum

Summary The radioligand binding characteristics of [³H]haloperidol (in the presence of spiperone, 25 nmolL^–1) were investigated in rat and human cerebellar membranes.In both rat and human cerebellar membrane preparations saturation studies with [³H]haloperidol (non-specific binding defined by pentazocine, 10 molL^–1) demonstrated high affinity saturable specific binding to a homogenous population of binding sites (rat, Bmax 6693 ± 1242 fmol mg^–1 protein, pK_D 8.33 ± 0.08; human, Bmax 2550 ± 437 fmol mg^–1 protein, pK_D 8.59 ± 0.11; mean ± SEM, n = 3–6). Competition studies employing a wide range of structurally diverse competing compounds displayed that the [³H]haloperidol binding site was pharmacologically similar in both preparations and comparable to sigma recognition sites previously identified in various tissues originating from different species. In addition, with reference to the potential subtypes of sigma recognition sites, the labelling of these sites by low nanomolar concentrations of [³H]haloperidol provides evidence that they belong to the sigma-1 recognition site subtype.The present findings suggest that the pharmacology of the rat and human cerebellar sigma recognition site are directly comparable and provides further supporting evidence towards the use of [³H]haloperidol radioligand binding studies in the rat to detect sigma receptor ligands with potential therapeutic activity. Send offprint requests to: N.M. Barnes at the above address     

Low doses of oxytocin facilitate social recognition in rats

Social recognition of juveniles by adult male residents has been shown to be modulated by neurohypophyseal hormones. The decrease of social investigation behavior during a second encounter with the same juvenile serves as index for social recognition. In the present study it was found that low doses (0.09–6.0 ng · kg^–1) of oxytocin (OXT) given subcutaneously dose dependently facilitated social recognition. The effect of OXT appeared specific, since no change in social investigation was found when a novel juvenile was tested during the second encounter. No disturbances of social recognition by the low doses of OXT could be detected, in contrast to higher doses of this hormone. Other neurohypophyseal hormones, vasopressin and vasotocin, did not facilitate social recognition when tested in the same range of low doses.     

Scopolamine Effects on Visual Information Processing, Attention, and Event-Related Potential Map Latencies

We measured performance and event-related brain potential (ERP) map latencies in 12 subjects during four visual discrimination tasks to compare the timing of scopolamine effects on information processing and attention. "Topographic component recognition" found ERP map latencies at times of best fit with a component model map. This "common topography" criterion minimized topographic differences among conditions to facilitate latency interpretations. Scopolamine slowed N1 latency in all tasks, and P3 and reaction time in some tasks. The drug delayed responses to easy targets more than to hard targets. It also induced a disproportionate N1 delay for unilateral high spatial frequency gratings. Both effects reflect a scopolamine-induced impairment when processing targets that usually capture attention. Scopolamine also impaired accuracy for unilateral high spatial frequency gratings, and for gratings presented at probable locations, confirming and extending previous findings. Scopolamine-induced P1 and N1 delays showed that visual processing was affected. Several results were inconsistent with a serial stage model. We suggest that scopolamine both delays selected processes and impairs a processing mode based on automatic capture of attention, inducing more serial processing.     

Scale-invariant superiority of foveal vision in perceptual categorization

The recognition of objects is exceedingly difficult in indirect view. This complication cannot be explained in terms of retino-cortical magnification, as size scaling fails to establish position invariance both for character recognition [Strasburger, H. & Rentschler, I. (1996) Eur. J. Neurosci., 8 1787-1791] and pattern classification [Jüttner, M. & Rentschler, I. (1996) Vision Res., 36, 1007-1021]. Thus we compared, for two tasks of discrimination learning and category learning with respect to a common set of grey-level patterns, how humans perform in foveal and extrafoveal vision. Observers learnt to discriminate (size-scaled) images equally well in foveal and extrafoveal view, whereas they displayed profound deficiencies in extrafoveal category learning for the same patterns. From the behavioural learning data, internal representations of the learning signals were reconstructed by means of computer simulations. For foveal view, these representations were found to be veridical to their physical counterparts for both learning tasks. For extrafoveal view, they were severely distorted for category learning but not for discrimination learning. A variance reduction of the pattern classes by a factor of 100 reduced the dissociation between extrafoveal categorization and discrimination but did not remove it. These observations suggest a scale-invariant superiority of foveal vision for learning object categories. This implies a high degree of space variance of visual cognition which is vastly underestimated by classical measures of visual performance, e.g. acuity, visual field and contrast sensitivity.     

聋儿配戴助听器后使用无线调频语训系统的效果评估

目的：研究和比较全数字助听器与无线调频语训（FM）系统不同结合方式对重度听力损失儿童的助听效果，方法：聋儿双耳分别配戴全数字助听器，双耳全数字助听器结合单耳FM系统，双耳全数字助听器结合双耳FM系统，在安静和噪声环境中，以不同强度的言语声测试言语可懂度，比较在安静环境和噪声环境中使用与不同使用FM系统及单耳使用与双耳同时使用的助听效果。结果：在安静和噪声环境下，使用FM系统的言语可懂度优于不使用该系统（P＜0．05），单耳使用该系统和双耳使用该系统无明显差异（P＞0．05）。结论：聋儿配戴助听器使用无线调频语训系统在安静和噪声环境下言语可懂度高于不使用该系统者。     

人体寄生虫虫卵图像的自动识别

本文对显微医学图像的自动识别进行了初步研究，在微型计算机上实现了血吸虫等十余种人体寄生虫虫卵显微图像的预处理、分割、特征提取及识别与分类。通过对一批检验样本的识别分类，取得了正确率为９２％的较好结果。