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.     

Catheter Ablation of Chronic Atrial Fibrillation with Noncontact Mapping:

SEIDL, K., et al .: Catheter Ablation of Chronic Atrial Fibrillation with Noncontact Mapping: Are Continuous Linear Lesions Associated with Ablation Success? Catheter-based, right and left atrial compartmentalization procedure was evaluated using a noncontact mapping (NCM) system. Its usefulness to identify and close discontinuities in linear lesions in both atria was evaluated. The impact of linear lesion continuity on ablation success of chronic AF was also investigated. Nineteen patients with symptomatic, drug refractory chronic AF were studied. Right atrial ablation with three predefined lines was attempted in all patients. In 18 patients, left atrial ablation was performed with four linear lesions. During a follow-up of 12 ± 3 months , 6 of 19 patients remained in sinus rhythm (SR) without antiarrhythmic agents (AAs). In addition, four patients were maintained in SR with AA. Thirteen of 14 patients with gaps identified during off-line analysis had recurrence of AF. Only one patient with a gap was free of recurrence without AAs. In the remaining five patients without recurrence of AF, no gap was observed during off-line analysis. In all four patients who were free of AF with additional treatment of AAs, two gaps had been identified. In the remaining nine patients with chronic AF recurrence, a mean of 4.9 gaps were identified. Excluding the initial learning period (first five patients) the success rate increased to 43% (6/14 patients) without and to 71% (10/14 patients) with AA. NCM identifies discontinuities in lines of ablation. Successful ablation of chronic AF is associated with continuity of linear lesions and good clinical technique demands a vigilant search for and closure of every gap. (PACE 2003; 26[Pt. I]:534–543)     

重组大鼠TGF-β1在大肠杆菌的表达及初步鉴定

β型转化生长因子 (ＴＧＦ β)有 5种不同的异构体 ,其中ＴＧＦ β1研究最为深入 ,由于ＴＧＦ β1对多种脏器纤维化及肿瘤的发生、发展有关而倍受关注。哺乳动物细胞合成的ＴＧＦ β1前体含 390个氨基酸 ,其中包含Ｎ 端信号肽(ａａ 1 2 3) ,ＬＡＰ(ｌａｔｅｎｔａｓｓｏｃｉａｔｅｐｅｐｔｉｄｅ) (ａａ2 3 2 78)和 112个氨基酸的Ｃ端肽 (ａａ2 79 390 ) ,在ａａ 2 75～ 2 78有四个碱性氨基酸组成的酶解位点 ,Ｃ端肽可从该位点酶解释放最终形成成熟态的ＴＧＦ β1单体 ,活性ＴＧＦ β1即为该单体的同种二聚体。本文克隆了编码 2 79～ 390氨…     

Solid-phase synthesis of H- and methylphosphonopeptides

We introduce solid-phase syntheses of H- and methylphosphonopeptides, giving access for the first time to a new class of mimics for o-phosphoamino acids. The model peptides H-GlyGlyXaaAla-OH (Xaa = Ser, Thr) were synthesized on a solid-phase using Fmoc/^tBu strategy and HBTU/HOBt activation by incorporation of hydroxyl-protected serine and threonine. As selectively cleavable hydroxyl-protecting groups we used triphenylmethyl and tert-butyldimethylsilyl for both amino acids, as described in the literature. All peptides were phosphitilated with O,O-di-tert-butyl-N,N-diethylphosphoramidite and yielded H-phosphonopeptides after trifluoroacetic acid cleavage. Alternatively we phosphonylated the peptides with O-tert-butyl-N,N-diethyl-P-methylphosphonamidite, which was synthesized by a two-step one-pot procedure starting from commercially available chemicals. All H- and methylphosphonopeptides were obtained in high purities and yields, as shown by reversed-phase high-performance liquid chromatography and anion-exchange chromatography. The phosphonopeptides were characterized by ¹H and ³¹P NMR. We confirmed their molecular masses by electrospray mass spectrometry and analyzed their fragmentation schemes, which seemed to be characteristic for each class of analogues. The H-phosphonopeptides lost phosphonic acid (H₃PO₃, 82 mass units) and the methylphosphonopeptides lost methylphosphonic acid (MeH₂PO₃, 96 mass units). Both H- and methylphosphonopeptides represent a new and simply accessible class of mimics for phosphopeptides. Compared with the corresponding phosphopeptides all phosphonopeptides were synthesized in higher yields and purities (>80%). © Munksgaard 1996.     

Physico-chemical characterization of legumin-T from faba bean (Vicia faba L.)

Legumin-T, the high-molecular mass product of limited tryptic hydrolysis of faba bean legumin, was investigated using hydrodynamic methods, static light scattering, fluorescence and ultraviolet spectroscopy. The following physico-chemical parameters were determined in a high-ionic strength buffer system: molecular mass, 2.4 × 10⁵ g/mol; sedimentation coefficient, s³₁₀= 10.8 × 10^?13s_i; diffusion coefficient, D⁰₂₀= 4.1 × 10^?7 cm² s^?1; intrinsic viscosity, [n] = 3.51 mL/g; partial specific volume, v∣?= O.719 mL/g; frictional ratio, f/f_o= 1.22; shape factor, β= 2.17 × 10⁶. Conformational changes during the formation of legumin-T can be deduced from the fluorescence emission and UV spectra. © Munksgaard 1996     

Trimethylmethoxyphenyl-retinoic acid (Ro 10–1670) inhibits mitogen-induced DNA-synthesis in peripheral blood lymphocytes in vitro

Trimethylmethoxyphenyl-retinoic acid (TMMP-retinoic acid, Ro 10-1670) is the main metabolite of the aromatic retinoid Ro 10-9359 (Tigason, etretinate), which is now in clinical use. Therefore, we selected this metabolite for our in vitro studies on human lymphocytes. The following findings were obtained: TMMP-retinoic acid is practically insoluble in aqueous solution. It remains partly in solution only if bound to protein. Under these conditions it had no influence on DNA-synthesis of human peripheral blood lymphocytes added in vitro without lectins (5--12.5 ng/ml culture medium). However, if human peripheral blood lymphocytes were cultured in vitro with lectins (ConA, PHA-M, PHA-P and PWM) and in the presence of TMMP-retinoic acid (25 microgram/ml culture medium) no induction of DNA-synthesis was seen. The altered lymphocytic response in presence of TMMP-retinoid in vitro was clearly dose-dependent at these levels. Trypan blue exclusion tests showed no evidence of cytotoxicity. Our studies clearly indicate that TMMP-retinoic acid inhibits the biological response of human blood lymphocytes to lectins in vitro, at dosages close to therapeutic levels in vivo. They confirm that retinoids may exert distinct effects on dermal cells in addition to their influence on keratinocytes, and suggest that the therapeutic action of the drug may be also related to the altered lymphocytic response.