非右房肥大的P波高电压(附39例临床分析)

本文报告39例临床上除外右房肥大的P波高电压,此种P波高电压主要见于冠心病及急性颅脑疾患,二者之和占76.9%。其形态64%与肺性P波相同。产生的机制可能与结间束传导阻滞、中枢调节机能受累、交感神经兴奋性增高等有关。     

Comparative early and midterm results of open juxtarenal and infrarenal aneurysm repair

Background and aims Since the introduction of endovascular aortic aneurysm repair (EVAR) for aortic aneurysms, the number of juxtarenal aortic aneurysms (JRA) has been growing steadily due to selection bias (neck morphology for EVAR). This case-match study compares the perioperative outcome and midterm results of suprarenally clamped JRA with infrarenal aortic aneurysms (AAA). Methods From 1997 to 2004, patients who received open surgery with suprarenal clamping for JRA were included in the study and compared to matched patients with infrarenal clamping (AAA). Measurements analyzed were the in-hospital mortality and morbidity. Midterm results were obtained through clinical investigation and magnetic resonance angiography imaging. Results Thirty-five patients (mean age, 68.4 years; 30 male and 5 female) received suprarenal cross-clamping for JRA. The overall in-hospital mortality for JRA and for the controls (AAA) with elective aortic repair was 4.5% (6.1% JRA; 3% AAA, p = 0.058). The morbidity of JRA was elevated according to the rate of pulmonary complications (p = 0.021) and the need for re-operation (p = 0.019). The mean follow-up time was 2.3 years (range, 8–96 months). At follow-up, 28 patients (80%) from the JRA group and 29 patients from the AAA group (82.9%) were alive. Conclusion Open aortic surgery for JRA with the need for suprarenal cross-clamping shows a slightly elevated in-hospital mortality rate without statistical significance and equal midterm mortality results in comparison with infrarenally clamped aortic aneurysms.     

The effects of changes to action potential duration on the calcium content of the sarcoplasmic reticulum in isolated guinea-pig ventricular myocytes

. We have estimated sarcoplasmic reticulum calcium content using rapid application of caffeine on voltage clamped, isolated guinea-pig ventricular myocytes. Caffeine induces the release of calcium from the sarcoplasmic reticulum and this calcium is extruded from the cells by the sarcolemmal Na/Ca exchange. Integrating the inward Na/Ca exchange current thus allows estimations of sarcoplasmic reticulum calcium content. Ventricular myocytes were stimulated to reach new steady-states by action potential voltage clamps of varying duration. Once contractile steady-state had been reached caffeine was rapidly applied in place of the next action potential and sarcoplasmic reticulum calcium content measured. Prolonging the action potential duration increased sarcoplasmic reticulum calcium content and vice-versa. This calcium loading may underlie the positive inotropic effect of increased action potential duration. Received: 11 July 1996 / Received after revision: 15 October 1996 / Accepted: 26 November 1996     

Electrophysiological Characterization of a Novel Conotoxin That Blocks Molluscan Sodium Channels

A novel peptide toxin, PnIVB, isolated from the venom of Conus pennaceus blocks voltage-gated sodium current in Aplysia neurons. Complete blockade is obtained at a PnIVB concentration of 80±2.2 nM and 50% blockade at 16±0.86 nM. The potency of PnIVB in blocking Aplysia sodium current is four orders of magnitude larger than that of tetrodotoxin. The toxin has no paralytic activity when injected into fish. The rapid blockade of sodium current by PnIVB is not associated with a change in the activation or inactivation kinetics of the current, or with the reversal potential. Sodium current blockade is reversible after a 30 min wash with 50 times the bath volume. The novel conotoxin PnlVB can be used as a powerful tool for mollusc neurobiological research and as a molecular probe to explore the structure-function relations of voltage-gated sodium channel subtypes.     

高电压胸部摄影诊断和防护效果研究

作者以体模实验为基础。测定了不同管电压拍摄胸片时的病人剂量，考察了提高管电压对胶片影像质量的影响，结果表明，使用高电压拍摄胸片比使用低电压有利于降低病人剂量，在增加影像信息量，提高肋骨阴影区和纵膈区灶检出率方面更有较大优越性，此外，使用高电压技术不家利于延长Ｘ射线管的使用寿命。     

微波照射对小鼠海马细胞膜ATPase活性和离子通道的影响

目的从电生理、酶学角度探讨微波照射对海马细胞的影响机理。方法用 2 4 5 0MHz连续波照射理疗机为照射源 ,以小白鼠为对象 ,观察微波照射强度为 1 0mW /cm2 时小鼠海马细胞膜Na+,K+ AT Pase、Ca2 +,Mg2 + ATPase活性、电压门控型Na+、K+、Ca2 +通道的变化情况 ,分别用组织化学染色法和膜片钳方法测定ATPase活性和离子通道功能。结果 1 )照射组海马Na+,K+ ATPase活性与对照组无显著差别 ,Ca2 +,Mg2 + ATPase活性比对照组显著降低 (P <0 .0 5 ) ;2 )照射组静息电位未发生显著变化 ,电压门控型Na+、K+、Ca2 +电流的诱导发生率显著地低于对照组 ,Na+电流峰值所在膜电位向去极化方向偏移 ,Na+电流衰减速率减慢 ,A电流的发生率显著低于对照。结论 2 4 5 0MHz微波照射小鼠 ,在 1 0mW /cm2 时 ,细胞的生存不会受影响 ,但海马细胞膜Ca2 +,Mg2 + ATPase活性受到抑制 ,电压门控型Na+、K+、Ca2 +离子通道受到损害 ,有可能影响学习记忆功能     

WHERE ARE THE GATES IN GAP JUNCTION CHANNELS?

1. In the formation and function of gap junction channels two types of gates ought to be discriminated: the docking gate and the channel gates proper. The docking gate is involved in the transformation of a closed hemichannel to a patent gap junction channel. By definition the trigger mechanism for this gate and maybe even the gate itself is contained within the extracellular loops of the gap junction proteins, the connexins. The channel gates proper determine the open and closed states of the complete gap junction channels. 2. Probing the docking gate by mutagenesis of connexins and by synthetic peptides indicates that this gate is the consequence of complex interactions between a large fraction of the amino acids comprising the extracellular loops. Probably both inter- and intra-molecular interactions are involved, and disulfide exchange may be entailed in the stabilization of the open and closed states. 3. Of the various effectors on the channel gate(s) the voltage effects have obtained the most scrutiny to date. The response of gap junction channels and hemichannels is diverse, the various channels respond differently to transjunctional and membrane potential. No equivalent to the S4 segment representing the voltage sensor in other voltage dependent ion channels is present in the connexin sequences, instead mutations in various segments of connexins have been reported to affect the voltage dependence of gap junction channels. To understand the complexity of voltage effects on gap junction channels, non-connexin peptides may need to be considered as voltage sensors or as modifiers thereof.     

Effects of glucagon-like peptide 1 (7–36 amide) on whole-body protein metabolism in healthy man

The incretin glucagon-like peptide 1 (GLP-1) shows glucose-dependent insulinotropic activity and may exert anabolic effects. Whole-body protein metabolism was assessed by measuring [1-¹³C]-leucine kinetics in 13 healthy volunteers during hyperglycaemic clamping with or without pancreatic clamping (somatostatin infusion) in order to differentiate between insulin-mediated and direct GLP-1 effects. During intact pancreatic secretion leucine flux and leucine oxidation rate as parameters of whole-body protein breakdown decreased markedly after 180 min of synthetic GLP-1 infusion (GLP-1 vs. placebo: P  < 0.003). Indirect calorimetry showed an increase in energy expenditure and CO₂ production during GLP-1 administration ( P  < 0.0005). Plasma insulin increased after 3 h of GLP-1 infusion to 1486 ± 145 pmol L⁻¹ vs. 185 ± 12 pmol L⁻¹ for saline ( P  < 0.0001). When plasma insulin levels were kept constant (GLP-1 vs. saline, NS) during pancreatic clamping, GLP-1 effects on both protein metabolism and energy expenditure were abolished. Thus, GLP-1 infusion in man exerts protein anticatabolic and thermic effects, which are mediated by GLP-1-induced stimulation of insulin secretion.     

体表电位标测微机系统(Ⅰ型)

本系统的107个电极中,103个分布于胸、背部,1个为参考电极,1个为V_3,其余用于肢导。本系统除能绘出2、4、8ms任意间隔的103通道同步的体表等电位图,常规12导联和V_(7 9)心电图,胸、背部位的心电图外,还可记录R峰值等电位图,∑R,Q波等电位图,nQ30、40,极大、极小轨迹图等。