Resonance Rayleigh scattering method for the recognition and determination of double-stranded DNA using amikacin

In weakly acidic buffer medium, the interaction of amikacin with calf thymus DNA, yeast RNA and denatured DNA has been investigated by using resonance Rayleigh scattering (RRS) technique. The result shows that calf thymus DNA is capable of enhancing the RRS intensity of the amikacin, while yeast RNA and denatured DNA have very little enhancement effect. Based on the characteristics, a sensitive assay for detecting double-stranded DNA in the presence of denatured DNA and yeast RNA has been developed. The enhancement of the RRS signal is directly proportional to the concentration of double-stranded DNA in the range 0.02-12.0 μg ml⁻¹ for calf thymus DNA and its detection limit (3σ) is 2.5 ng ml⁻¹. The method shows a wide linear range and high sensitivity, and almost no interference can be observed from RNA, denatured DNA, amino acid and most of the metal ions. The trace amounts of nucleic acid in synthetic samples and practical samples are determined with satisfactory results. Therefore, the proposed method is promising for as an effect means for recognition in vivo and determination in situ of double-stranded DNA.     

51VNMR研究磷钼钒系杂多酸的热稳定性

用NMR及IR、TG-DTA等手段研究具有Keggin结构的磷钼钒系杂多酸在空气中的热稳定性。实验结果表明:合成的杂多酸在各个Keggin单元中具有不同的钒含量。样品的热稳定性与其钒含量有关.随着钒含量的增加,keggin结构的热稳定性逐渐降低,但H_4PMo_(11)V_1O_(40)具有比H_3PMo_(12)O_(40)还要高的热稳定性。由于钒的取代,钼钒磷酸的热分解过程不同于钼磷酸。失去结构水使Keggin结构遭到破坏,但在室温下与水重新作用可使钼钒磷酸的Keggin结构恢复。     

鸟嘌呤与Cu(Ⅰ)配位作用的极谱研究

在0.02mol/L NaHCO_3-0.05mol/L Na_2SO_4(pH9)介质中,对鸟嘌呤与Cu(Ⅰ)的配位作用进行了极谱研究,测定了鸟嘌呤与Cu(Ⅰ)配位的配体数(2)和该配合物的条件形成常数(β_1=1.80×10~(14),β_2=2.85×10~(18)),并对DcFord-Hume公式的适用性作了讨论.     

含双二苯基膦甲烷铜(Ⅰ)配合物的研究进展

本文概述了含双二苯基膦甲烷铜(Ⅰ)配合物的化学进展,总结了配合物的合成方法:置换法、还原法、电化学方法和直接加成法,全面论述了双核、三核、多核和异核配合物的结构特征,探讨了该类配合物的重要荧光性质。     

Linear scaling local correlation approach for solving the coupled cluster equations of large systems

A linear scaling local correlation approach is proposed for approximately solving the coupled cluster doubles (CCD) equations of large systems in a basis of orthogonal localized molecular orbitals (LMOs). By restricting double excitations from spatially close occupied LMOs into their associated virtual LMOs, the number of significant excitation amplitudes scales only linearly with molecular size in large molecules. Significant amplitudes are obtained to a very good approximation by solving the CCD equations of various subsystems, each of which is made up of a cluster associated with the orbital indices of a subset of significant amplitudes and the local environmental domain of the cluster. The combined effect of these two approximations leads to a linear scaling algorithm for large systems. By using typical thresholds, which are designed to target an energy accuracy, our numerical calculations for a wide range of molecules using the 6-31G or 6-31G* basis set demonstrate that the present local correlation approach recovers more than 98.5% of the conventional CCD correlation energy.     

2-Deoxy-d-glucose Promotes Buforin IIb-Induced Cytotoxicity in Prostate Cancer DU145 Cells and Xenograft Tumors

Inhibition of the glycolytic pathway is a critical strategy in anticancer therapy because of the role of aerobic glycolysis in cancer cells. The glycolytic inhibitor 2-Deoxy-d-glucose (2-DG) has shown potential in combination with other anticancer agents. Buforin IIb is an effective antimicrobial peptide (AMP) with broad-spectrum anticancer activity and selectivity. The efficacy of combination treatment with 2-DG and buforin IIb in prostate cancer remains unknown. Here, we tested the efficacy of buforin IIb as a mitochondria-targeting AMP in the androgen-independent human prostate cancer cell line DU145. Combining 2-DG with buforin IIb had a synergistic toxic effect on DU145 cells and mouse xenograft tumors. Combination treatment with 2-DG and buforin IIb caused stronger proliferation inhibition, greater G1 cell cycle arrest, and higher apoptosis than either treatment alone. Combination treatment dramatically decreased L-lactate production and intracellular ATP levels, indicating severe inhibition of glycolysis and ATP production. Flow cytometry and confocal laser scanning microscopy results indicate that 2-DG may increase buforin IIb uptake by DU145 cells, thereby increasing the mitochondria-targeting capacity of buforin IIb. This may partly explain the effect of combination treatment on enhancing buforin IIb-induced apoptosis. Consistently, 2-DG increased mitochondrial dysfunction and upregulated Bax/Bcl-2, promoting cytochrome c release to initiate procaspase 3 cleavage induced by buforin IIb. These results suggest that 2-DG sensitizes prostate cancer DU145 cells to buforin IIb. Moreover, combination treatment caused minimal hemolysis and cytotoxicity to normal WPMY-1 cells. Collectively, the current study demonstrates that dual targeting of glycolysis and mitochondria by 2-DG and buforin IIb may be an effective anticancer strategy for the treatment of some advanced prostate cancer.     

Novel 1,3,5-thiadiazine-2-thione derivatives containing a hydrazide moiety: Design,synthesis and bioactive evaluation against phytopathogenic fungi in vitro and in vivo

A series of novel 1,3,5-thiadiazine-2-thione derivatives bearing a hydrazide moiety were designed, synthesized and evaluated for their biological activities against phytopathogenic fungi. The antifungal bioassays indicated that the title compound 5b impressively displayed the obvious selectivity and specificity aganist Rhizoctonia solani (Rs) in vitro and in vivo. The above researches provide a significant reference for the further structural optimization of 1,3,5-thiadiazine-2-thione derivatives bearing a hydrazide moiety as potential fungicides.     

Speciation analysis of aluminium(III) in natural waters and biological fluids by complexing with various catechols followed by differential pulse voltammetry detection

The biological effects of aluminium have received much attention in recent years. Speciation of Al is of basic relevance as it concerns its reactivity and bioavailability. A differential pulse voltammetry (DPV) procedure is proposed for speciation analysis of Al(III) in natural waters and biological fluids using six catechols (L-dopa, dopamine, epinephrine, norepinephrine, caffeic acid and o-benzenediol) as electroactive ligands. The decrease of the DPV anodic peak current for each catechol ligand is linear with the increase of Al concentration. This speciation analysis idea is based on the measurement of the complexation capacity, namely, different affinities of Al(III) for catechols and organic ligands under two pH conditions. The labile monomeric Al fraction (mainly inorganic aluminium) is determined at pH 4.6, while the total monomeric Al fraction is determined at pH 8.5. The principle for Al(III) speciation analysis by an electrochemical method is discussed. This sensitive and simple fractionation method is successfully applied to the speciation analysis of Al in natural waters and the results agree well with those of Driscoll's method. The speciation analysis of Al in biological fluids is also explored and the results are compared with those obtained by ultrafiltration and dialysis. Compared with other speciation protocols the electrochemical method possesses some remarkable advantages: rapidity, high sensitivity, cheap instrumentation and a simple operation procedure.     

新型光学活性α-氨基磷酸及其酯合成进展

α-氨基膦酸酯是一类很重要的天然氨基酸类似物，具有新颖的化学结构和多 种生理活性。综述了近年来光学活性α-氨基膦酸及酯的合成进展。     

阴离子对水的羟基伸缩振动拉曼光谱的影响

通过比较纯水、NaX(X=F, Cl, Br, I)、Na2S、NaOH、NaNO3、Na2CO3、Na2SO4溶液的羟基伸缩振动拉曼光谱, 发现所研究的阴离子对水的结构都有破坏作用. 通过比较阴离子对水的羟基伸缩振动拉曼光谱的影响, 可将所研究的阴离子分为两类, 一类阴离子有F−、OH−、S2−、CO32−, 另一类阴离子有Cl−、Br−、I−、NO3−和SO42−. 它们的主要区别在于对羟基伸缩振动拉曼光谱3600 cm−1、2900−3100 cm−1处影响不同, 产生这些区别的原因在于阴离子与水分子之间氢键的强弱. 阴离子对水的羟基伸缩振动拉曼光谱的影响因素有离子半径、离子电荷和离子结构, 它们的影响程度为离子结构>离子电荷>离子半径.