镁合金AZ31B材料表性与成骨细胞的黏附

背景：镁合金对成骨细胞的生物学行为及早期黏附是否有影响尚不明确。 目的：分析镁合金AZ31B的表性,并评价其对成骨细胞黏附的影响。 方法：采用扫描电镜及能谱分析明确镁合金AZ31B的表面形态及元素组成。以蛋白吸附实验检测镁合金AZ31B与钛合金对蛋白的吸附能力。将镁合金AZ31B与钛合金分别与小鼠前成骨细胞MC3T3-El共培养于24孔板内,观察培养2,6,24 h的细胞黏附情况。 结果与结论：扫描电镜可见镁合金AZ31B表面较为粗糙,有利于细胞在其表面的黏附.能谱分析结果表明镁合金AZ31B的主要元素有镁、铝、锌,其中镁约占96%,铝约占3%,锌约占1%,另有一些其他元素,含量较少。镁合金AZ31B与钛合金的蛋白吸附率差异无显著性意义。培养2 h时,镁合金AZ31B与钛合金上的细胞黏附率差异无显著性意义;培养6,24 h,镁合金AZ31B上的细胞黏附率显著低于钛合金上的细胞黏附率(P < 0.01)。培养于镁合金表面的成骨细胞贴壁展开,形态不规则,大多呈梭形,有较多突起,部分细胞间突起相互连接。表明镁合金AZ31B具有良好的细胞黏附性,适合于成骨细胞的早期黏附。     

Intracellular alkalinization causes Mg2+ release from intracellular binding sites in leech Retzius neurones

 Four-barrelled ion-sensitive microelectrodes were developed to enable simultaneous measurement of intracellular free Mg²⁺ and Na⁺ concentrations ([Mg²⁺]_i, [Na⁺]_i), intracellular pH and the membrane potential. The electrodes were used to investigate pH-induced [Mg²⁺]_i changes in Retzius neurones of the leech Hirudo medicinalis. The application of propionate or CO₂/HCO₃ ^–-buffered bath solutions caused a transient intracellular acidification, an initial [Mg²⁺]_i decrease and a continuous [Na⁺]_i increase. In the presence of CO₂/HCO₃ ^– this [Na⁺]_i increase was more pronounced and might be the reason for the slow increase in [Mg²⁺]_i following the initial decrease. The withdrawal of propionate or CO₂/HCO₃ ^–-buffered bath solutions caused a transient alkalinization which was accompanied by a slight but significant [Mg²⁺]_i increase, even in the nominal absence of extracellular Mg²⁺, while [Na⁺]_i returned to its original value. The alkalinization-induced [Mg²⁺]_i increase could be reduced to about 50% by the application of 1–10 μM cyclosporin A, an inhibitor of the mitochondrial permeability transition pore (MTP). Phenylarsine oxide, an MTP activator, caused a [Mg²⁺]_i increase with characteristics similar to those of the alkalinization-induced increase, which could not be attributed to any changes in [Na⁺]_i or pH_i. It is concluded that an intracellular alkalinization might induce the release of Mg²⁺ from intracellular stores. Received: 8 May 1997 / Received after revision: 31 July 1997 / Accepted: 19 August 1997     

异甘草酸镁干预肝纤维化大鼠肝细胞体积与数量的体视学

目的:探讨异甘草酸镁(MgIG)对四氯化碳(CCl4)致大鼠肝纤维化模型肝细胞数量与体积的影响.方法:雄性SD大鼠随机分为对照组、模型组、治疗组,治疗组给予CCl4皮下注射,同时每日腹腔注射MgIG?30 mg/?kg.各组大鼠在造模5周后取材,从每只大鼠等距抽选4个2 mm厚的肝组织块制作石蜡包埋切片,行Masson...     

静脉肾盂造影检查前3种肠道准备方法的临床效果比较观察

目的探讨静脉肾盂造影(IVP)检查前肠道准备中提高肠道清洁度,减轻患者痛苦的方法。方法120例泌尿系结石病人进行IVP检查前肠道准备,采用口服便塞停、硫酸镁和甘露醇的方法,分别观察3组患者肠道清洁度、药物不良反应及患者的耐受性等。结果口服便塞停组与口服硫酸镁组、口服甘露醇组肠道清洁度比较无显著性差异(P>0.05),但不良反应发生率有显著性差异(P<0.01)。结论口服便塞停片是一种安全、有效的肠道准备方法,患者痛苦少,适合静脉肾盂造影检查(IVP)前的肠道准备。     

CaO-MgO-P_2O_5-SiO_2-CaF_2系统自硬性玻璃的研究

为研究钙离子、镁离子在体内环境中对自硬性玻璃结晶行为的影响,为自硬性生物活性玻璃的临床应用提供依据,本文设计了CaO-P2O5-SiO2-CaF2(Ca-glass)和CaO-MgO-P2O5-SiO2-CaF2(CaMg-glass)系统玻璃并使用模拟体液(simulated body flu id,SBF)进行了研究。首先采用磷酸氢二氨[(NH4)2HPO4]/[NH4H2PO4]硬化液与Ca-glass、CaMg-glass制成硬化体,然后使用X射线衍射(XRD)、扫描电镜(SEM)、失重、力学分析等方法,研究硬化体在SBF中的结晶性、降解性和力学性能。实验结果表明,玻璃粉末与磷酸铵缓冲溶液反应形成了磷酸铵钙[(NH4)2.Ca(HPO4)2.H2O]硬化体。硬化体经过SBF浸泡,Ca-glass系统硬化体中部分磷酸铵钙转化成羟基磷灰石,而CaMg-glass系统硬化体仍然为磷酸铵钙。Ca-glass与CaMg-glass硬化体在SBF中浸泡28天分别降解19.4%和31.3%,抗压强度分别为93.14MPa和64.52MPa。镁离子的歧化作用是导致Ca-glass、CaMg-glass硬化体结晶性能、降解性能以及力学性能差别的主要原因。     

Online Prediction of Onsets of Seizure-like Events in Hippocampal Neural Networks Using Wavelet Artificial Neural Networks

It has been previously shown that wavelet artificial neural networks (WANNs) are able to classify the different states of epileptiform activity and predict the onsets of seizure-like events (SLEs) by offline processing (Ann. Biomed. Eng. 33(6):798–810, 2005) of the electrical data from the in-vitro hippocampal slice model of recurrent spontaneous SLEs. The WANN design entailed the assumption that time-varying frequency information from the biological recordings can be used to estimate the times at which onsets of SLEs would most likely occur in the future. Progressions of different frequency components were captured by the artificial neural network (ANN) using selective frequency inputs from the initial wavelet transform of the biological data. The training of the WANN had been established using 184 SLE episodes in 34 slices from 21 rats offline. Nine of these rats also exhibited periods of interictal bursts (IBs). These IBs were included as part of the training to help distinguish the difference in dynamics of bursting activities between the preictal- and interictal type. In this paper, we present the results of an online processing using WANN on 23 in-vitro rat hippocampal slices from 9 rats having 93 spontaneous SLE episodes generated under low magnesium conditions. Over the test cases, three of the nine rats exhibited over 30 min of IB activities. We demonstrated that the WANN was able to classify the different states, namely, interictal, preictal, ictal, and IB activities with an accuracy of 86.6, 72.6, 84.5, and 69.1%, respectively. Prediction of state transitions into ictal events was achieved using regression of initial “normalized time-to-onset” estimates. The SLE onsets can be estimated up to 36.4 s ahead of their actual occurrences, with a mean error of 14.3 ± 27.0 s. The prediction errors decreased progressively as the actual time-to-onset decreased and more initial “normalized time-to-onset” estimates were used for the regression procedure.     

生物可降解镁合金支架研究现状

目前介入治疗中主要以金属永久性支架为主,这类支架存在血栓形成和再狭窄的问题.生物可降解镁合金支架开始成为关注的焦点和热点,它理论上克服了永久性支架的缺点,是未来支架发展方向之一.相信在不久的将来,生物可降解镁合金支架在许多疾病中都将得到广泛应用.     

镁合金支架植入兔腹主动脉后降解时间及血管内膜增生观察

目的 观察新型可降解镁合金支架——MPM植入兔腹主动脉后降解时间及血管内膜增生.方法 24只新西兰大白兔随机分为4组,每组6只,分别于距左肾动脉水平下1 cm腹主动脉处植入MPM支架各1枚.术后30、60、90、180 d分别复查腹主动脉造影,分离支架段血管进行观察.采用SPSS20.0软件对数据进行分析.结果 24只实验兔在随访期间存活良好.植入支架逐渐降解,180 d时基本降解;血管内膜增生,90 d时达峰值,整个降解过程血管通畅.结论 可降解镁合金支架MPM完全降解时间为182 d,可满足血管正性重塑.     

Magnesium sulfate effectively reduces blood pressure in an animal model of preeclampsia

Objective.?We tested the ability of magnesium sulfate to reduce hypertension and neonatal growth retardation in an animal model of preeclampsia.

Study design.?On day 17 of pregnancy, osmotic minipumps were inserted subcutaneously to continuously deliver either vehicle (saline control group), or N-nitro-l-arginine methyl ester (L-NAME) (50 mg/kg/day), or L-NAME (50 mg/kg/day) in combination with magnesium sulfate (60 mg/kg/day). Prior to insertion, blood pressure and heart rate were monitored with a pneumatic tail cuff device. Blood pressure measurements were repeated on days 18, 20, and 21 of pregnancy. Blood was obtained on days 17 and 21, along with urine, to assess magnesium levels and degree of proteinuria. Pups were weighed and measured at 48 hours postpartum.

Results.?Rats receiving L-NAME developed hypertension within 24 hours of implantation (108 ± 3.9 vs. 123 ± 3.4 mmHg, p < 0.05). Magnesium sulfate, given along with L-NAME did not prevent mean blood pressure from increasing, but reduced it by day 21 compared to L-NAME given alone (107 ± 3.4 vs. 122 ± 8.7 mmHg, respectively, p < 0.05). Magnesium sulfate reduced neonatal growth retardation by improving the weight of the pups compared to pups from maternal rats given L-NAME alone (6.1 ± 0.1 vs. 5.2 ± 0.3 grams, respectively, p < 0.05).

Conclusion.?Maternal magnesium sulfate reduces blood pressure and increases neonatal size compared to L-NAME without magnesium. These findings support a beneficial effect of magnesium in preeclampsia.     

Umbilical artery pH may be a possible confounder for neonatal adverse outcomes in preterm infants exposed to antenatal magnesium

Objectives: To determine the normal range of ionized magnesium (IMg) levels in cord blood during preterm gestation and to investigate whether antenatal Mg administration affects neonatal intraventricular hemorrhage (IVH) or patent ductus arteriosus (PDA). Methods: In this retrospective case–control study, we reviewed 118 pregnant women with antenatal Mg administration and their infants after they gave birth at one tertiary care center between January 2006 and December 2010. Thirty-seven cases with IVH and/or PDA were compared to 81 controls by multiple logistic regression analysis. The normal range of IMg levels was determined by another 79 subjects without any tocolytic agents and possible confounders. Perinatal and neonatal characteristics were then compared between three groups divided by the IMg levels in cord serum. Results: The normal range of IMg levels in cord blood was determined to be 0.47?±?0.07 mmol/L, regardless of gestational weeks. IMg level in cord serum could not be a risk factor for IVH or PDA. Elevation of IMg level in cord blood resulted in an increased incidence of IVH and a decreased incidence of PDA, but not significantly. IMg level in cord blood was inversely correlated with umbilical artery pH (p = 0.067). Conclusions: There was no significant relationship between the IMg levels in cord serum and neonatal IVH and PDA. Umbilical artery pH may be a possible confounder.