Neuroprotective Effect of Phlorotannin Isolated from Ishige okamurae Against H2O2-Induced Oxidative Stress in Murine Hippocampal Neuronal Cells, HT22

The present study is designed to investigate the neuroprotective effect of a kind of phlorotannins, diphlorethohydroxycarmalol (DPHC) isolated from Ishige okamurae against hydrogen peroxide (H₂O₂)-induced oxidative stress in murine hippocampal neuronal cells, HT22. H₂O₂ treatment induced neurotoxicity, whereas DPHC prevented cells from H₂O₂-induced damage then restoring cell viability was significantly increased. DPHC slightly reduced the expression of Bax induced by H₂O₂ but recovered the expression of Bcl-xL as well as caspase-9 and -3 mediated PARP cleavage by H₂O₂. Intracellular reactive oxygen species (ROS) and lipid peroxidation was overproduced as the result of the addition of H₂O₂; however, these ROS generations and lipid peroxidation were effectively inhibited by addition of DPHC in a dose-dependent manner. Moreover, DPHC suppressed the elevation of H₂O₂-induced Ca²⁺ release. These findings indicate that DPHC has neuroprotective effects against H₂O₂-induced damage in neuronal cells, and that an inhibitory effect on ROS production may contribute to the underlying mechanisms.     

Cleistocalyx nervosum var. paniala Berry Promotes Antioxidant Response and Suppresses Glutamate-Induced Cell Death via SIRT1/Nrf2 Survival Pathway in Hippocampal HT22 Neuronal Cells

Excessive glutamate neurotransmitters result in oxidative neurotoxicity, similar to neurodegeneration. An indigenous berry of Thailand, Cleistocalyx nervosum var. paniala (CNP), has been recognized for its robust antioxidants. We investigated the effects and mechanisms of CNP fruit extracts on antioxidant-related survival pathways against glutamate-induced neurotoxicity. The extract showed strong antioxidant capability and had high total phenolic and flavonoid contents, particularly resveratrol. Next, the protective effects of the CNP extract or resveratrol on the glutamate-induced neurotoxicity were examined in HT22 hippocampal cells. Our investigation showed that the pretreatment of cells with the CNP extract or resveratrol attenuated glutamate-induced neuronal death via suppression of apoptosis cascade by inhibiting the levels of cleaved- and pro-caspase-3 proteins. The CNP extract and resveratrol suppressed the intracellular ROS by increasing the mRNA expression level of antioxidant enzymes (SODs, GPx1, and CAT). We found that this extract and resveratrol significantly increased SIRT1 expression as a survival-related protein. Moreover, they also promoted the activity of the Nrf2 protein translocation into the nucleus and could bind to the promoter containing the antioxidant response element, inducing the expression of the downstream GPx1-antioxidant protein. Our data illustrate that the CNP extract and resveratrol inhibit apoptotic neuronal death via glutamate-induced oxidative neurotoxicity in HT22 cells through the activation of the SIRT1/Nrf2 survival mechanism.     

八肋游仆虫中心蛋白N端半分子Loop区首个氨基酸的作用

本文通过分子生物学方法将八肋游仆虫中心蛋白N端半分子loop区的首个氨基酸,天冬氨酸Asp37和Asp73,分别突变为带相反电荷的赖氨酸。使用铽敏化荧光、TNS疏水探针研究了八肋游仆虫中心蛋白N端半分子loop区的首个氨基酸的作用。结果表明：当中心蛋白loop Ⅰ区37位的天冬氨酸突变为赖氨酸后,loop Ⅰ丧失了金属离子结合能力,进而影响了中心蛋白依赖于金属离子的构象变化;而loop Ⅱ区73位的天冬氨酸突变为赖氨酸后仍保持金属离子结合能力,依赖于金属离子的构象变化减小。中心蛋白发挥大部分生物功能都依赖于金属离子,这就表明loop Ⅰ区37位的天冬氨酸在中心蛋白发挥生物功能时起着重要作用,是不可缺少的。在10 mmol·L^-1 Hepes、pH 7.4、20 mmol·L^-1 KCl条件下,八肋游仆虫中心蛋白N端半分子loop Ⅱ与金属离子Tb³⁺和Ca²⁺的结合常数分别为：K_Ⅱ(Tb³⁺)=(8.31±0.18)×10⁴ L·mol^-1和K_Ⅱ(Ca²⁺)=(0.94±0.12)×10² L·mol^-1,中心蛋白N端半分子的两个金属结合部位结合能力顺序为：Ⅰ>Ⅱ。     

希土化合物对离体巨噬细胞的影响

本文应用细胞培养法和单细胞阳离子测定系统研究了希土化合物以地巨噬细胞的影响，结果表明，在培养介质中ＳｍＣｌ３和Ｙｃｌ３的浓度大于１ｍｍｏｌ．ｄｍ＾－３时，有明显的细胞毒性，Ｙｃｌ３的细胞毒性大于ＳｍＣｌ３，ＳｍＣｌ３和ＹＣｌ３的细胞毒性明显大于Ｓｍ（Ａｌａ）３Ｃｌ３和Ｙ（Ａｌａ）２Ｃｌ３。希土化合物的作用使细胞（Ｃａ＾２＋ｉ）升高；毒性越大，Ｃａ＾２＋ｉ升高越甚。低浓度Ｓｍ＾３＋和Ｙ６３＋对细胞膜     

八肋游仆虫中心蛋白N-端半分子与Tb3+，Ca2+的结合

用分子生物学方法表达、纯化了游仆虫中心蛋白及N-端半分子，用铽荧光探针法、离子竞争法研究了pH 7.4，0.01 mol· L^-1 Hepes条件下中心蛋白与铽、钙的结合性质。结果表明中心蛋白有4个铽结合部位，其中2个为高亲合结合部位、2个为低亲合结合部位。具有2个低亲合结合部位的中心蛋白半分子与铽结合的条件常数是(2.13±0.10)×10⁵ L·mol^-1，与钙结合的条件常数是(7.52±0.02)×10² L·mol^-1。     

M(NTEA)配合物的NMR研究

用ＮＭＲ方法研究了氨三乙氧基乙酸（ＮＴＥＡ）的质子解离过程及其与Ｌａ３＋、Ｙ３＋、Ｌｕ３＋和Ｃａ２＋的配合作用．ＮＴＥＡ的氮原子和羧基的质子解离常数分别为８．８和３．０．当ｐＨ＞３．０时，Ｌａ３＋、Ｙ３＋和Ｌｕ３＋配合物能稳定形成（＞５０％），而Ｃａ２＋配合物则需出＞５．在ｐＨ３～６范围内，配合物与配体间的交换反应处于慢－中介交换速率区间，通过变温谱模拟得到了其交换反应的动力学参数．     

Study of Complex Formation Between Dicyclohexano-18-Crown-6 (DCH18C6) with Mg 2+, Ca2+, Sr 2+, and Ba2+ Cations in Methanol–Water Binary Mixtures Using Conductometric Method

The complexation reactions between Mg²⁺,Ca²⁺,Sr²⁺ and Ba²⁺ metal cations with macrocyclic ligand, dicyclohexano-18-crown-6 (DCH18C6) were studied in methanol (MeOH)–water (H₂O) binary mixtures at different temperatures using conductometric method . In all cases, DCH18C6 forms 1:1 complexes with these metal cations. The values of stability constants of complexes which were obtained from conductometric data show that the stability of complexes is affected by the nature and composition of the mixed solvents. While the variation of stability constants of DCH18C6-Sr ²⁺ and DCH18C6-Ba²⁺versus the composition of MeOH–H₂O mixed solvents is monotonic, an anomalous behavior was observed for variations of stability constants of DCH18C6-Mg²⁺ and DCH18C6-Ca²⁺ versus the composition of the mixed solvents. The values of thermodynamic parameters (ΔH_c°, ΔS_c°) for complexation reactions were obtained from temperature dependence of formation constants of complexes using the van’t Hoff plots. The results show that in most cases, the complexation reactions are enthalpy stabilized but entropy destabilized and the values of thermodynamic parameters are influenced by the nature and composition of the mixed solvents. The obtained results show that the order of selectivity of DCH18C6 ligand for metal cations in different concentrations of methanol in MeOH–H₂O binary system is: Ba²⁺>Sr²⁺>Ca²⁺> Mg²⁺.     

Safranal Induces Vasorelaxation by Inhibiting Ca2+ Influx and Na+/Ca2+ Exchanger in Isolated Rat Aortic Rings

Introduction: Safranal, which endows saffron its unique aroma, causes vasodilatation and has a hypotensive effect in animal studies, but the mechanisms of these effects are unknown. In this study, we investigated the mechanisms of safranal vasodilation. Methods: Isolated rat endothelium-intact or -denuded aortic rings were precontracted with phenylephrine and then relaxed with safranal. To further assess the involvement of nitric oxide, prostaglandins, guanylate cyclase, and phospholipase A₂ in safranal-induced vasodilation, aortic rings were preincubated with L-NAME, indomethacin, methylene blue, or quinacrine, respectively, then precontracted with phenylephrine, and safranal concentration–response curves were established. To explore the effects of safranal on Ca²⁺ influx, phenylephrine and CaCl₂ concentration–response curves were established in the presence of safranal. Furthermore, the effect of safranal on aortic rings in the presence of ouabain, a Na⁺-K⁺ ATPase inhibitor, was studied to explore the contribution of Na⁺/Ca²⁺ exchanger to this vasodilation. Results: Safranal caused vasodilation in endothelium-intact and endothelium-denuded aortic rings. The vasodilation was not eliminated by pretreatment with L-NAME, indomethacin, methylene blue, or quinacrine, indicating the lack of a role for NO/cGMP. Safranal significantly inhibited the maximum contractions induced by phenylephrine, or by CaCl₂ in Ca²⁺-free depolarizing buffer. Safranal also relaxed contractions induced by ouabain, but pretreatment with safranal totally abolished the development of ouabain contractions. Discussion/Conclusion: Inhibition of Na⁺-K⁺ ATPase by ouabain leads to the accumulation of Na⁺ intracellularly, forcing the Na⁺/Ca²⁺ exchanger to work in reverse mode, thus causing a contraction. Inhibition of the development of this contraction by preincubation with safranal indicates that safranal inhibited the Na⁺/Ca²⁺ exchanger. We conclude that safranal vasodilation is mediated by the inhibition of calcium influx from extracellular space through L-type Ca²⁺ channels and by the inhibition of the Na⁺/Ca²⁺ exchanger.     

Comparison of Partial Least Squares Regression and H-Point Standard Addition Method for Simultaneous Spectrophotometric Determination of Zinc, Cobalt and Nickel by 1-(2-Pyridylazo)2-Naphthol in Micellar Media

Simultaneous spectrophotometric methods are described for the determination of Zn²⁺, Co²⁺ and Ni²⁺ by 1-(2-pyridylazo)2-naphthol (PAN) in micellar media, using absorbance correction-H-point standard addition method (HPSAM) and partial least squares (PLS) regression. The ligand and its metal complexes, i.e. Zn²⁺-PAN, Co²⁺-PAN and Ni²⁺-PAN, were made water-soluble by the neutral surfactant Triton X-100, and therefore extraction with organic solvents was no longer required. Formation of all of these complexes was complete within 10min at pH 9.2. The linear range was 0.1–1.5mgL^–1 for Zn²⁺, 0.1–2.0mgL^–1 for Co²⁺ and 0.1–2.0mgL^–1 for Ni²⁺. The relative standard deviation (RSD) for the simultaneous determination of 0.50mgL^–1 each of Zn²⁺, Ni²⁺ and Co²⁺ by applying the H-point standard addition method was 2.55%, 2.04% and 3.70%, respectively. The total relative standard error for applying the PLS method to 9 synthetic samples in the linear ranges of these metals was 1.8%. Interference effects of common anions and cations were studied, and both methods were applied to the simultaneous determination of Zn²⁺, Co²⁺ and Ni²⁺ in alloy samples.     

Thermal investigations of nitrate-hydrates and deuterates of Ca2+, Cd2+ and Mg2+

DTA and DSC were used to study the thermal behaviour of Ca(NO₃)₂·4H₂O, Cd(NO₃)₂·4H₂O, Mg(NO₃)₂·6H₂O and their deuterated analogues. Evidence was found concerning the process of melting of the initial hydrates and deuterates, followed by a one-stage dehydration of the melt to vield the respective anhydrous salt. T _m, ΔH _m ^o , ΔS _m ^o and ΔH _deh ^o were determined and the ΔH _f ^o values for the investigated hydrates were calculated from the ΔH _deh ^o data.

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Zusammenfassung DTA und DSC wurden zur Untersuchung des thermischen Verhaltens von Ca(NO₃)₂·4H₂O, Cd(NO₃)₂·4H₂O, Mg(NO₃)₂·6H₂O und ihrer deuterierten Analoge eingesetzt. Man fand Aussagen bezüglich des Schmelzvorganges der Ausgangshydrate und Deuterate, gefolgt von einer Einschritt-Dehydratation der Schmelze unter Bildung der entsprechenden wasserfreien Salze. T _m, ΔH _m ^o , ΔS _m ^o und ΔH _deh ^o wurden ermittelt und die ΔH _f ^o Werte für die untersuchten Hydrate wurden anhand der ΔH _deh ^o berechnet.

     

电解液对全铅单液流电池电极性能的影响

研究Pb(II)和H+离子浓度对全铅单液流电池正、负电极在复合石墨基体上电化学行为的影响.结果表明,PbO2正极和Pb负极的电极过程受电化学和扩散混合控制.Pb(II)氧化沉积成PbO2时出现成核环,铅负极成核过电位小,充放电电压差远小于PbO2正极,电池极化主要来自PbO2正极.增加H+浓度有利于降低PbO2正极和Pb负极的极化,但析氧、析氢副反应和腐蚀加重.增大Pb(II)浓度有利于抑制析氧,但PbO2正极充电电压升高,充放电电压差增大.Pb(II)浓度较低时,充放电过程中PbO2沉积层少许脱落,充电电压进一步降低且更趋平稳.为此,电解液中HBF4浓度以2 mol L-1为宜,Pb(II)浓度应在0.9 mol L-1以上.     

Characterization of a Hg2+-Selective Fluorescent Probe Based on Rhodamine B and Its Imaging in Living Cells

A small organic molecule P was synthesized and characterized as a fluorometric and colorimetric dual-modal probe for Hg²⁺. The sensing characteristics of the proposed probe for Hg²⁺ were studied in detail. A fluorescent enhancing property at 583 nm (>30 fold) accompanied with a visible colorimetric change, from colorless to pink, was observed with the addition of Hg²⁺ to P in an ethanol-water solution (8:2, v/v, 20 mM HEPES, pH 7.0), which would be helpful to fabricate Hg²⁺-selective probes with “naked-eye” and fluorescent detection. Meanwhile, cellular experimental results demonstrated its low cytotoxicity and good biocompatibility, and the application of P for imaging of Hg²⁺ in living cells was satisfactory.     

淋巴细胞膜上Na+/Ca2+交换操纵的Eu3+内流的荧光法研究

利用Fura-2荧光浓度指示剂法、通过检测360nm激发荧光强度的变化,研究了Eu³⁺能否利用人外周血淋巴细胞膜上的Na⁺/Ca²⁺交换进入细胞。结果表明:用ouabain预处理细胞无Na⁺介质中测试,当加入Eu³⁺时,360nm荧光强度发生猝灭,且随着胞外加入的Eu³⁺浓度的增大而猝灭增强。表明在实验条件下Eu³⁺可以进入细胞。电压依赖性Ca     

Study on the synthesis of novel fluorescent macrocyclic sensors and their sensitive properties for Cu2+ and Fe3+ in aqueous solution

In this work, we synthesised and characterised three novel fluorescence macrocyclic sensors containing optically active dansyl groups. The studies for the interaction of the synthesised compounds with various mental ions (Li⁺, Na⁺, K⁺, Ag⁺, Mg²⁺, Ca²⁺, Ba²⁺, Pb²⁺, Zn²⁺, Co²⁺, Cd²⁺, Hg²⁺, Ni²⁺, Cu²⁺, Mn²⁺, Cr³⁺, Al³⁺, Fe³⁺) were performed by fluorescence titration, Job’s plot, ESI-MS and DFT calculations. The results showed that the sensors 1a–1c displayed selective recognition for Cu²⁺ and Fe³⁺ ions and formed stoichiometry 1:1 complex through PET mechanism in DMSO/H₂O solution (1:1, v/v, pH 7.4 of HEPES). The binding constant (K) and detection limit were calculated.     

Facile Synthesis of Aminated Graphene Quantum Dots for Promising and Selective Detection of Cobalt and Copper Ions in Aqueous Media

Due to the rapid development of industrialization, various environmental problems such as water resource pollution are gradually emerging, among which heavy metal pollution is harmful to both human beings and the environment. As a result, there are many metal ion detection methods, among which fluorescence detection stands out because of its rapid, sensitive, low cost and non-toxic characteristics. In recent years, graphene quantum dots have been widely used and studied due to their excellent properties such as high stability, low toxicity and water solubility, and have a broad prospect in the field of metal ion detection. A novel high fluorescence Cu²⁺, Co²⁺ sensing probe produced by graphene quantum hydrothermal treatment is reported. After heat treatment with hydrazine hydrate, the small-molecule precursor nitronaphthalene synthesized by self-nitrification was transformed from blue fluorescent GQDs to green fluorescent amino-functionalized N–GQDs. Compared with other metal ions, N–GQDs are more sensitive to Cu²⁺ and Co²⁺ on the surface, and N–GQDs have much higher selectivity to Cu²⁺ and Co²⁺ than GQDs. The strategy proposed here is simple and economical in design.     

Vanillin Induces Relaxation in Rat Mesenteric Resistance Arteries by Inhibiting Extracellular Ca2+ Influx

Vanillin is a phenolic aldehyde, which is found in plant species of the Vanilla genus. Although recent studies have suggested that vanillin has various beneficial properties, the effect of vanillin on blood vessels has not been studied well. In the present study, we investigated whether vanillin has vascular effects in rat mesenteric resistance arteries. To examine the vascular effect of vanillin, we measured the isometric tension of arteries using a multi-wire myograph system. After the arteries were pre-contracted with high K⁺ (70 mM) or phenylephrine (5 µM), vanillin was administered. Vanillin induced concentration-dependent vasodilation. Endothelial denudation or treatment of eNOS inhibitor (L-NNA, 300 μM) did not affect the vasodilation induced by vanillin. Treatment of K⁺ channel inhibitor (TEA, 10 mM) or sGC inhibitor (ODQ, 10 μM) or COX-2 inhibitor (indomethacin, 10 μM) did not affect the vanillin-induced vasodilation either. The treatment of vanillin decreased the contractile responses induced by Ca²⁺ addition. Furthermore, vanillin significantly reduced vascular contraction induced by BAY K 8644 (30 nM). Vanillin induced concentration-dependent vascular relaxation in rat mesenteric resistance arteries, which was endothelium-independent. Inhibition of extracellular Ca²⁺ influx was involved in vanillin-induced vasodilation. Treatment of vanillin reduced phopsho-MLC₂₀ in vascular smooth muscle cells. These results suggest the possibility of vanillin as a potent vasodilatory molecule.     

Effects of BaCl<Subscript>2</Subscript> on slow vacuolar ion channels on radish by patch-clamp

The effects of BaCl₂ on slow vacuolar (SV) currents of radish are studied by using the whole-vacuolar patch-clamp recording mode. The Ca²⁺-dependent SV channel can be activated by cytosolic Ca²⁺. When 1 mmol/L BaCl₂ is added into pipette solution, SV currents are suppressed remarkably. Then adding BaCl₂ of different concentrations into the bath solution, SV currents reflect different effects. The results show that BaCl₂ with a lower concentration (<3 mmol/L) promotes the channel currents and the currents are saturated when BaCl₂ concentrations are between 1 μmol/L and 1 mmol/L, but BaCl₂ with higher concentration (≥ 3 mmol/L) inhibits SV currents.     

苯乙烯三嗪衍生物的合成及在重金属离子识别中的应用

合成了2,4-二(2-噻吩乙烯基)-6-(4'-N,N-二甲氨基苯乙烯基)-1,3,5-均三嗪(2)并鉴定了其结构。在乙腈-水混合介质中,化合物2在355和416nm处呈现双吸收峰,加入Cu²⁺,Hg²⁺ 和Fe³⁺ 后,均在520nm附近形成新的吸收峰。化合物2与Cu²⁺、Hg²⁺ 和Fe³⁺ 均形成1:1型配合物,其结合常数分别为1.9×10⁵L·mol^-1,6.6×10³L·mol^-1,2.7×10³L·mol^-1。对照化合物4与金属离子的光谱响应与化合物2相似,仅吸收峰的位置不同。因此,可认为化合物2和4中三嗪环中的N和噻吩环中的S与Cu²⁺、Hg²⁺ 和Fe³⁺ 共同配位形成了稳定的金属配合物。     

A confocal study of mechanism of 5-hydroxytryptamino induced intracellular calcium dynamics in cultured rat stomach fundus smooth muscle cells with a new Ca2+ indicator STDln-AM

A new fluorescent Ca²⁺ indicator STDln-AM for detecting [Ca²⁺], transients in cultured smooth muscle cells is presented. By making a comparison, the difference between STDln and fluo-3 is discussed in detail. Using the new Ca²⁺ indicator, the mechanism of 5-hydroxytryptamino (5-HT) induced intracellular calcium dynamics in stomach fundus smooth muscle cells (SFSMC) of rats is investigated. It is shown that in contrast with fluo-3, STDln is uniformly distributed in the cytosolic compartment but excluded from the nucleus, when it is transfected into cells. This feature makes it a real cytosol Ca²⁺ indicator and can reflect changes of cytosol [Ca²⁺] more accurately than that of fluo-3. In addition, STDln responds to the [Ca²⁺], transients more sensitive and faster than fluo-3. The results also show that, the L-type Ca²⁺ channel inhibitor Mn9202 and the PLC inhibitor Compound 48/80 can significantly inhibit the [Ca²⁺], elevation induced by 5-HT, while the PKC inhibitor D-Sphingosine can enhance the effect of 5-HT. The results suggest that 5-HT acts by the way of 5-HT₂ receptors on SFSMC, then through 5-HT₂ receptors coupled IP₃/Ca²⁺ and GC/PKC double signal transduction pathways to make Ca²⁺ release from intracellular Ca²⁺ stores and Ca²⁺ influx possibly through L-type calcium channels.