透析液钙离子浓度对肾功能衰竭血液透析患者血清钙离子水平及血压的影响

目的 观察不同钙离子浓度的透析液对血液透析患者透析后血清钙离子水平及血压变化的影响，为肾功能衰竭血液透析患者的高钙血症及高血压的防治提供依据。方法 选择不同钙离子浓度的透析液，将维持性血液透析患者分为高钙组（1．75mmol／L）和低钙组（1．25mmol／L），比较患者每次透析前后脉搏、血压，同时抽查患者透析前后血钙及血肌酐浓度的变化。结果透析后两组患者血肌酐浓度均显著下降，透析前后差异均具有统计学意义（P〈0．01）；高钙组患者透析后血钙较透析前升高，差异具有统计学意义（P〈0．01），而低钙组患者血钙比透析前略降低，差异无统计学意义（P〉0．05）。高钙组患者透析后较透析前收缩压、舒张压及平均动脉压都升高，差异均具有统计学意义（P〈0．05），而低钙组患者透析后较透析前收缩压、舒张压及平均动脉压都降低，差异均具有统计学意义（P〈0．05）。透析后两组血钙比较差异具有统计学意义（P〈0．01）；透析后低钙组较高钙组患者的收缩压、舒张压及平均动脉压都降低，三者差异均具有统计学意义（P〈0．01）。结论透析液钙离子浓度与血液透析患者血清钙离子水平及血压呈正相关，低钙透析液透析有助于维持性血液透析患者高血压的控制。     

Ex vivo identification of atherosclerotic plaque calcification by a 31P solid-state magnetic resonance imaging technique.

Calcified tissue is a common component of atherosclerotic plaques, and occurs most often in mature plaques. The process of calcification is a poorly understood risk factor that may contribute to a plaque's vulnerability to sudden rupture. In this study a solid-state imaging sequence, termed single-point imaging (SPI), was used to observe calcification directly in ex vivo atherosclerotic plaques. Standards were used to validate the ability of (31)P SPI to detect and differentiate calcification from crystalline cholesterol, phospholipids, and other plaque components. After suitable experimental parameters were found, human carotid specimens obtained by endarterectomy were imaged ex vivo by (31)P solid-state imaging and standard (1)H methods. In contrast to (1)H imaging methods, (31)P imaging detected only the calcification in the plaque.     

缺氧缺血性脑病新生鼠补钙前后脑细胞,红细胞内外钙的变化

为了观察一般剂量补钙对缺氧缺血性脑病（ＨＩＥ）脑细胞和红细胞内外钙变化的影响，以探讨ＨＩＥ时补钙是否增加脑细胞钙超载，用ＨＩＥ新生动物模型进行了实验研究，结果表明：（１）缺氧缺血时红细胞、脑细胞及脑组织出现钙积聚；（２）补钙后，血浆总钙浓度明显升高，而脑细胞、脑组织及红细胞钙积聚并未加重；（３）血浆总钙浓度与脑细胞或红细胞胞浆游离钙离子浓度无相关关系。提示：（１）ＨＩＥ时钙内流可能是全身性的；（２）对ＨＩＥ并低钙血症患儿吸氧后一般剂量补钙可能是安全的。     

心钠素对心肌血管钙超载的影响

提要本研究是在大鼠VD_3+Nicotine引起的心血管钙超载模型上观察心钠素(ANF)治疗(10ug ·kg~-1/d),对钙超载的影响。结果发现,钙超载组动物主动脉、心肌组织钙含量较对照组分别增高24倍(54.4±2.2vs 2.3±0.04fumol/gww)和9倍(16.9±2.1vs1.8±0.1umol/gww)。ANF治疗能显著抑制钙超载的发生,主动脉和心肌组织钙含量较钙超载组分别降低92％(3.8±0.4 umol/gww)和66％(5.6±0.6umol/gww)。离体滋流的钙超载血管环较对照组对去甲肾上腺素收缩反应增强;对乙酰胆碱舒张反应减弱,对硝普钠舒张反应无影响。ANF能显著改善钙超载所致的血管反应性障碍。实验结果表明,ANF具有显著的防治心血管钙超载的作用。     

A Clinical Study of Reversing Left Ventricular Hypertrophy in Hypertensive Patients by Adalat

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New peritoneal dialysis solutions

Summary: Current peritoneal dialysis solutions are not biocompatible, particularly in respect to low pH, high osmolality and use of lactate. In addition, glucose is not an ideal osmotic agent. Recent advances in the formulation of peritoneal dialysis fluids aim to provide a more physiological environment to preserve membrane integrity. the effects of pH and lactate have been overcome by the use of bicarbonate based solutions whilst icodextrin (glucose polymers) often prolonged ultrafiltration in spite of being isomotic to uraemic plasma. Future formulations will see a combination of osmotic agents (including amino acids) and bicarbonate to achieve a more biocompatible solution whilst still meeting the ultrafiltration needs of the patients. Additives (glycosaminoglycans, procysteine) may protect the peritoneum from free radical injury.     

l-DOPA induces concentration-dependent facilitation and inhibition of presynaptic acetylcholine release in the guinea-pig submucous plexus

Neurotransmitter- or neuromodulator-like actions ofl-DOPA were investigated with intracellular recordings from submucous plexus neurons of the guinea-pig caecum.l-DOPA at 30 nM augmented the amplitude of fast EPSPs, but did not affect depolarizations elicited by puff application of acetylcholine (ACh). The augmenting effect ofl-DOPA on the fast EPSPs was counteracted byl-DOPA methyl ester. The fast EPSPs were depressed by 10 μMl-DOPA, but transiently augmented after rinsing the drug.l-DOPA methyl ester did not affect the inhibitory action ofl-DOPA on the fast EPSPs, but antagonized the potentiation following the inhibition. The depolarization elicited by exogenously applied. ACh was inhibited by 10 μMl-DOPA. Intracellular Ca²⁺ concentrations ([Ca²⁺]_i) of the neuronal soma were measured with fura-2 microfluorophotometry. The transient increase in the [Ca²⁺]_i evoked by the somatic action potential (Δ[Ca²⁺]_AP) was facilitated by 30 nMl-DOPA, but decreased by the drug at 10 μM. It is concluded thatl-DOPA at low concentrations enhances the Δ[Ca²⁺]_AP, increasing the neurotransmitter release, but at high dose diminishes the Δ[Ca²⁺]_AP, inhibiting the neurotransmission.     

补钙预防结直肠息肉及结直肠癌的作用

本文概述了人体补充钙后对大肠息肉及结肠癌发生的影响。     

Release of corrosion products from amalgam in phosphate containing solutions

Abstract— The effect of phosphate concentration on corrosion was compared for two types of amalgam: a conventional alloy (ANA 68) and a high-Cu admixed alloy (Dispersalloy). The test specimens were stored for 4 months in electrolytes containing 85 mM NaCl and 85 mM NaCl with 2.5, 10, or 100 mM phosphate buffer respectively. The solutions were renewed each month and analyzed for Cu, Zn, Sn, Hg, and Ag in an atomic absorption spectrophotometer. The surfaces and cross-sections of the specimens were studied in a scanning electron microscope (SEM) with an energy dispersive detector (EDAX). The corrosion products, mainly Sn-compounds, at the surface of the amalgams were less in the solutions containing high concentrations of phosphate. In cross-section subsurface corrosion of the high-Cu amalgam was observed especially in specimens immersed in the NaCl solution without phosphate. The conventional amalgam showed surface corrosion only. The decrease in release of elements with time from the conventional amalgam in all the experimental solutions might indicate passivation. For the high-Cu amalgam the release of elements increased with time, except for Cu and Sn in the solution with 100 mM phosphate, indicating that phosphate inhibits corrosion of the Cu-Sn-phases. Release of corrosion products from the high-Cu amalgam was more dependent on the presence of phosphate than the conventional amalgam.     

Ineffectiveness of organic calcium channel blockers in antagonizing long-term potentiation

Evidence has accumulated suggesting that the presence of calcium is critical for development of hippocampal long-term potentiation (LTP). However, there is a paucity of information about whether calcium's role in LTP is pre- or postsynaptic. In the present study, we examined the effectiveness of nitrendipine, verapamil, flunarizine and the benzodiazepine diazepam in: blocking voltage-dependent calcium channels; blocking synaptic transmission; and preventing development of LTP. Using the in vitro slice preparation, we obtained intracellular and extracellular recordings from guinea pig hippocampal CA1 pyramidal cells. At the cellular level, all 4 drugs were ineffective in blocking voltage-dependent calcium spikes (TTX resistant) and the calcium-dependent afterhyperpolarization. Verapamil and diazepam appeared to antagonize synaptic transmission, as reflected in smaller population spike amplitudes. Development of long-term potentiation was not affected by the presence of verapamil, flunarizine and diazepam. Nitrendipine appeared to reduce the percentage of slices exhibiting LTP; however, ethanol, the vehicle used to dissolve nitrendipine, was shown in separate experiments to reduce the percentage of slices exhibiting LTP. These results suggest that neither the organic calcium channel blockers--nitrendipine, verapamil, and flunarizine--nor micromolar concentrations of diazepam are potent blockers of extrasynaptic voltage-sensitive calcium channels in hippocampus. They thus cannot be used to demonstrate a specific pre- or postsynaptic calcium role in LTP.