Electrophysiological actions of the plant alkaloid 6-benzoylheteratisine in rat hippocampal slices

The effects of the Aconitum alkaloid 6-benzoylheteratisine on neuronal activity was investigated in the in vitro slice preparation of rat hippocampus by extracellular recording of the stimulus-evoked population spike. 6-Benzoylheteratisine (0.01-10 μΜ) depressed the orthodromic and antidromic population spike in a concentration-dependent manner.The action of the drug was activity-dependent. The latency of onset of the inhibition was accelerated when the frequency of electrical stimulation had been increased. Furthermore, the effect of 6-benzoylheteratisine was evaluated in two different models of epileptiform activity induced either by blockade of GABA receptors by bicuculline (10 μΜ) or by a nominal Mg²⁺-free bathing medium. Due to the activity-dependent mode of action, this drug effectively reduced the number and the size of the synaptically evoked population spikes in the presence of bicuculline or nominal Mg²⁺-free bathing medium, respectively. Received: 23 September 1996 / Accepted: 2 January 1997     

氯菊酯和氯氰菊酯对大鼠脑突触体Ca~(2+)-和Ca~(2+),Mg~(2+)-ATP酶活性的抑制

氯菊酯可明显抑制Ca~(2+)—ATP酶活性,其抑制作用是可逆的,底物动力学分析表明为非竞争性抑制,介质的酸度可影响其抑制效应;氯氰菊酯对该酶活性无明显影响.氯菊酯和氯氰菊酯均能可逆性地抑制Ca~(2+),Mg~(2+)—ATP酶活性,但氯菊酯为反竞争性抑制.且有一定的pH依赖性,而氯氰菊酯为非竞争性抑制,其抑制率基本不受pH的影响,表明这两种杀虫剂在Ca~(2+) ,Mg~(2+)—ATP酶上有不同的结合位点.     

粤西砖红壤的镁素状况及其有效性

研究结果表明,粤西砖红壤的全镁含量普遍较低,玄武岩和花岗岩发育的土壤,全镁含量多在0.2％以下,浅海沉积物发育的土壤,全镁不足0.1％,玄武岩发育的土壤,交换性镁较丰,表土含量均在100ppm以上,镁饱和度较高;浅海沉积物和花岗岩发育的土壤,交换性镁贫缺,表土平均含量分别为16.7和14.7ppm,镁饱和度大都极低.土壤供镁能力的强弱依次是:玄武岩发育的砖红壤>浅海沉积物发育的砖红壤>花岗岩发育的砖红壤。交换性镁及镁饱和度与牧草的相对产量、吸镁量以及玉米小苗的含镁量、吸镁量的相关性达显著或极显著水平。据此初步认为可用作土壤镁素诊断指标。酸深性镁的有效性也较高,但因其释放速度较慢,不宜作为诊断指标,可用以评价土壤有效镁的补充能力。     

可吸收肋骨内固定装置的研究现状

多处肋骨骨折会导致胸腔变形,影响呼吸功能而需要手术固定。金属类固定装置力学性能好但需要二次手术移除,因此,可吸收类的内部肋骨固定材料受到越来越多的关注和使用。常用的可吸收装置一般由聚合物或者合金制成,其中聚左旋乳酸(PLLA)应用最为广泛,其降解速度和强度可以通过调节几种聚合物的比例控制;可降解类金属材料则可通过加入金属调控。继续改进和开发新的骨固定类装置的特性仍是可降解类材料未来发展的趋势之一。     

Nanoparticle Additivation Effects on Laser Powder Bed Fusion of Metals and Polymers—A Theoretical Concept for an Inter-Laboratory Study Design All Along the Process Chain,Including Research Data Management

In recent years, the application field of laser powder bed fusion of metals and polymers extends through an increasing variability of powder compositions in the market. New powder formulations such as nanoparticle (NP) additivated powder feedstocks are available today. Interestingly, they behave differently along with the entire laser powder bed fusion (PBF-LB) process chain, from flowability over absorbance and microstructure formation to processability and final part properties. Recent studies show that supporting NPs on metal and polymer powder feedstocks enhances processability, avoids crack formation, refines grain size, increases functionality, and improves as-built part properties. Although several inter-laboratory studies (ILSs) on metal and polymer PBF-LB exist, they mainly focus on mechanical properties and primarily ignore nano-additivated feedstocks or standardized assessment of powder feedstock properties. However, those studies must obtain reliable data to validate each property metric’s repeatability and reproducibility limits related to the PBF-LB process chain. We herein propose the design of a large-scale ILS to quantify the effect of nanoparticle additivation on powder characteristics, process behavior, microstructure, and part properties in PBF-LB. Besides the work and sample flow to organize the ILS, the test methods to measure the NP-additivated metal and polymer powder feedstock properties and resulting part properties are defined. A research data management (RDM) plan is designed to extract scientific results from the vast amount of material, process, and part data. The RDM focuses not only on the repeatability and reproducibility of a metric but also on the FAIR principle to include findable, accessible, interoperable, and reusable data/meta-data in additive manufacturing. The proposed ILS design gives access to principal component analysis (PCA) to compute the correlations between the material–process–microstructure–part properties.     

Mg~(2+)和Fe~(3+)对日本血吸虫毛蚴的趋向作用观察及在“模拟钉螺”中的应用

目的观察Mg2+、Fe3+对日本血吸虫毛蚴的趋向作用及其在"模拟钉螺"中的应用。方法采用改良Ro-berts比较法。结果加入1.00mol/L的Mg2+溶液时,实验组和对照组中日本血吸虫毛蚴的数目比为93和21(P0.01);Fe3+浓度为0.05、0.10、0.25、0.50和1.00mol/L时,实验组和对照组中日本血吸虫毛蚴的数目比分别是8l和29(P0.01)、24和5(P0.01)、225和39(P0.01)、41和7(P0.01)、52和17(P0.01)。一定配比的明胶混合物释放出的Fe3+吸引日本血吸虫毛蚴的能力强于钉螺处理过的水。结论适宜浓度的Mg2+和Fe3+能显著影响日本血吸虫毛蚴的趋向运动,"模拟钉螺"吸引日本血吸虫毛蚴的能力强于钉螺处理过的水。     

A Study on Spontaneously Obese Rat (Minko Rat) with Abnormal Lipid Metabolism,Strength and Mineral Concentrations in Bone

Objectives: In view of the prevalence of osteoporosis in Japan, which surveys have shown has almost doubled over the last ten years, contributory factors, additional to the mineral status, that affect bone stiffness have been explored in spontaneously obese (Minko) rats.

Methods: Bone stiffness and strength as well as content of Mg, Ca, P, Na, K, and trace minerals in femurs were compared in male and female Minko rats, which have abnormal lipid metabolism.

Results: Mechanical study of femurs indicated that bone stiffness of male rats was significantly higher than that of female rats, but that Mg, Ca, P, Na, Zn, Sr and Fe concentrations in male rats were significantly lower than that of female rats, while S and K concentrations in male rats were significantly higher than that of female rats.

Conclusions: These results suggest that bone strength isn’t determined only by mineral concentrations such as Mg, Ca and P. We reported that the bone strength of “Minko Rats” was significantly higher than bone strength of control rats, but there was no significant difference of Ca and P concentrations between the two groups of rats.     

Do Interictal Discharges Promote or Control Seizures? Experimental Evidence from an In Vitro Model of Epileptiform Discharge

Summary: Interictal and ictal discharges are recorded from limbic structures in temporal lobe epilepsy patients. In clinical practice, interictal spikes are used to localize the epileptogenic area, but they also are assumed to promote ictal events. Here I review data obtained from combined slices of mouse hippocampus–entorhinal cortex that indicate an inverse relation between interictal and ictal events. In this preparation, application of 4-aminopyridine or Mg²⁺-free medium induce (a) interictal discharges that originated from CA3 and propagate (via the Schaffer collaterals) to CA1 and entorhinal cortex, to return to the hippocampus through the dentate area; and (b) ictal discharges that initiate in the entorhinal cortex and propagate to the hippocampus via the dentate gyrus. Interictal activity occurs throughout the experiment (up to 6 h), whereas ictal discharges disappear after 1–2 h. Schaffer collateral cut abolishes interictal discharges in CA1, entorhinal cortex, and dentate and reestablishes entorhinal ictal discharges. Moreover, ictal discharge generation in the entorhinal cortex after Schaffer collateral cut is prevented by mimicking CA3 activity with rhythmic electrical stimulation of CA1 outputs. Thus hippocampal interictal activity controls the ability of the entorhinal cortex to generate seizures. It also may be proposed that Schaffer collateral cut may model the epileptic condition in which CA3 damage results in loss of hippocampal control over the entorhinal cortex. In conclusion, these experiments demonstrate that interictal activity controls rather than promotes ictal events, and functional integrity of CA3 constitutes a critical control mechanism in temporal lobe epilepsy.     

胃癌细胞三磷酸腺苷酶、5′—核苷酸酶和胞嘧啶单核苷酸酶活性定位的电镜细胞化学研究

应用电镜酶细胞化学方法对12例胃癌细胞三磷酸腺苷酶(Mg~(2+)—ATPase,Ca~(2+)—ATPase),5~1—核苷酸酶(5NPase)及胞嘧啶单核苷酸酶(CMPase)进行了超微结构水平的定位观察。结果表明:胃管状腺癌细胞腔缘微绒毛丰富,Mg~(2+)—ATPase、Ca~(2+)—ATPase及5NPase定位于微绒毛表面,反应明显,提示其功能代谢具有极性分布特点。粘液腺癌细胞出、入胞现象活跃,Mg~(2+)—ATPase、Ca~(2+)—ATPase及CMPase反应明显,认为与其粘液的大量分泌,营养物质的摄取与加工以及逃避免疫细胞的杀伤机制有关。低分化腺癌上述酶大都无反应或反应微弱。作者认为胃癌细胞的酶活性及其分布与其分化程度及功能状况有关。     

高原地区2型糖尿病患者微血管病变与血液学相关分析

目的探讨高原地区2型糖尿病患者血液学指标水平变化与微血管病变程度关系。方法在海拔2260m以上青海西宁地区选择137例2型糖尿病患者和82例健康者进行血小板计数（PLT）、血小板平均体积（MPV）、血小板分布宽度（PDW）、尿微量白蛋白（U-mAlb）、血清Mg2＋及糖化血红蛋白（HbAlc）测定,将两组结果进行比较分析。结果高原地区2型糖尿病组的HbAlc、PLT、MPV、PDW、U-mAlb、血清Mg2＋的浓度显著高于正常对照组（P〈0.01）。随着HbAlc水平增高,PLT、MPV、PDW、U-mAlb水平随之增高,血清Mg2＋有增高的趋势,呈显著正相关（P〈0.01）。结论2型糖尿病微血管病变程度与HbAlc的增高有关,血小板参数增高可作为血管及微血管病变的敏感指标,U-mAlb是糖尿病早期肾小球损伤的灵敏指标,微血管病变病情越重血清Mg2＋水平越高。