The Helmholtz Total Artificial Heart Labtype

Abstract: To perform the first experimental tests for validation of a new gear unit concept, the pump chamber, diaphragm, and pusher plate design of an orthotopic electromechanical total artificial heart (TAH) (Helmholtz Labtype) was manufactured. In its early stage of development, it provides some of the most important features of the conceptual final artificial heart. The new gear unit transforms a uniform unidirectional rotational motor movement into translatory pusher plate movements, with resting phase in the end–diastolic position, and the angled pump chamber orientation determines the available space for the motor and gear unit. Furthermore, this labtype provides flexibility with regard to use of different types of structural parts for experimental investigations. The first in vitro test results, obtained with specially designed circulatory mockloops that simulate physiological preload and afterload conditions, are presented. They comprise pressure and flow generation, motor performance, efficiency, and energy consumption. The results prove the feasability of the new gear unit concept for an electromechanical artificial heart and allow a reliable determination of the necessary performance of the future brushless DC motor for the first in vivo TAH model.     

Adaptive changes in cerebral blood flow and oxygen consumption during ethanol intoxication in the rat

Cerebral blood flow (CBF) and oxygen consumption (CMRO₂) were measured during acute and long-term ethanol intoxication in the rat. The purpose was to investigate whether the adaptive changes (development of tolerance) occurring in the CNS during ethanol intoxication were associated with changes in CBF and/or CMRO₂. Consistent with other studies we found that acute severe ethanol intoxication (median blood alcohol concentration (BAC=5.4 mg/ml)) caused a significant decrease in CBF and CMRO₂. After 3–4 days of severe intoxication (BAC of 6.6 mg/ml) these physiological variables were less affected indicating that functional tolerance had developed: CMRO₂ and CBF during acute ethanol intoxication were 9.3 ml/100 g/min and 60 ml/100 g/min respectively; after the long term intoxication period these variables reached 11.2 ml/100 g/min and 78 ml/100 g/min respectively, i.e. values not significantly lower than those of the control group. After induction of hypercapnia (PaCO₂ about 80 mmHg) CBF increased by 360% in the control group; in the acutely intoxicated group CBF increased by only 127% and in the long term intoxicated group by 203 % indicating that the cerebrovascular CO₂-reactivity had also adapted to the ethanol intoxication. It is concluded that adaptive changes of the CNS to chronic ethanol intoxication comprise alterations in CMRO₂, CBF and cerebrovascular reactivity.     

多发性脑膜瘤的临床和组织学研究

目的：研究多发性脑膜瘤的临床和组织学特点.方法：对39例多发性脑膜瘤的临床资料进行回顾性分析,免疫组化检测孕激素受体（PR）、p53和细胞周期蛋白抗体MIB-1在多发性脑膜瘤中的表达,并与单发性脑膜瘤进行比较.结果：多发性脑膜瘤女性多见,肿瘤的分布较为广泛,大脑半球凸面为好发部位.免疫组化结果显示：PR的表达在多发性脑膜瘤比单发性脑膜瘤强,p53和MIB-1的表达则两者无显著性差异.结论：多发性脑膜瘤的诊断主要依靠影像学资料,其发生学可能与孕激素及其受体有关,单克隆起源的可能性较大.     

Influence of different intragastric stimuli on triggering of transient lower oesophageal sphincter relaxation in the dog

Gastro-oesophageal reflux in the dog is mainly caused by transient lower oesophageal sphincter relaxation (TLOSR), the major stimulus for which is distension of the stomach. The possibility that liquid and/or acid sensors in the proximal stomach reduce the incidence and/or shorten the duration of TLOSR was addressed in the present study. Manometric recordings of the pharynx, oesophagus, lower oesophageal sphincter and stomach were made in awake dogs equipped with an oesophagostomy. TLOSRs were induced by insufflation of air or infusion of liquid nutrients with varying pH. Intragastric distension with air provoked TLOSRs with a significantly shorter duration than those seen after distension with liquid (4.3 +/- 0.5 vs 9.6 +/- 0.3 sec; P < 0.05). There were fewer TLOSRs at high intragastric pH (pH 5.0: 3.1 +/- 0.5/90 min) than at low pH (pH 1.5: 5.5 +/- 0.9/90 min, P < 0.05). Successfully propagated peristalsis following a TLOSR was more common after stimulation with liquid than with air. It can be concluded that there are H(+)-sensing mechanisms in the stomach which stimulate triggering of TLOSR. In addition, the reduced duration of TLOSR during air insufflation shows that the physical state of the distending stimulus can affect the patterning of TLOSR.