Interactions of Rare Earth-Amino Acid Complexes with Nucleic Acids

A number of metal-based anticancer drugs are designed to target nucleic acids. Therefore, the elucidation of their interactions with nucleic acids is important for rational design of new anticancer agents with high selectivity and low toxicity, which has been received much attention in this field. Lanthanide complexes have the potential to be therapeutic agents due to their unique magnetic, optical, electronic, and coordinate characteristics. However, lanthanide ions are easy to hydrolysis under physiological pH, which makes it difficult to study rare earth complexes nucleic acids selectivity. Recent studies have shown that natural amino acids can form stable complexes with rare earth ions under near physiological condition and the complexes have high solubility. This review summarizes the current progress in rare earth-amino acid complexes binding to nuclelic acids and their selectivity.

Assembly of 12-tungstosilicic acid and 4-aminobenzo-15-crown-5 ether based on the electrostatic attraction through bridging of oxonium ions on different substrates

Based on the electrostatic attraction Keggin-type polyoxometalate H4SiW12O40 (SiW12) and small molecule 4-aminobenzo-15-crown-5 ether (4-AB15C5) were alternately deposited on poly (allylamine hydrochloride) (PAH)-derived indium tin oxide (ITO) substrate through a layer-by-layer (LBL) self-assembly, forming a supramolecular multilayer film (film-A). SiW12 was also deposited on a glassy carbon electrode (GCE) derived by 4-AB15C5 via covalent bonding in 0.1 M NaCl aqueous solution and formed a composite monolayer film (film-B). UV-vis absorption spectroscopy, X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR) spectroscopy measurements demonstrated that the interactions between SiW12 and 4-AB15C5 in both two film electrodes were the same and caused by the bridging action of oxonium ions. But, the nanostructure in the two film electrodes was different. 4-AB15C5 in film-A was oriented horizontally to ITO substrate, however, that in film-B was oriented vertically to GCE. Namely film-A corresponded to a layer structure, and film-B corresponded to an intercalation structure.

Determination of total calcium in plasma by flow injection analysis with tris(2,2 '-bipyridyl)ruthenium(II) electrochemiluminescent detection

We described here a new method for the determination of total calcium in plasma. The method is based on the precipitation of calcium with excess oxalate and the measurement of residual oxalate by flow injection analysis with Ru(bpy)(3)(2+) electrochemiluminescent detection. It has the advantages of extremely stable reagent, user-friendly instrument, high selectivity, good analytical recovery, wide dynamic range, and nice correlation with atomic absorption spectroscopy. The calibration plot for calcium is linear over a concentration range from 0.5 mmol L-1 to 4.8 mmol L-1, which is wider than those obtained by most other methods. The analytical recoveries for plasma calcium are 98.4-101.2% with coefficients of variation (CVs) of 1.96-2.52%. The within-day CVs range from 0.76% to 0.95%, and between-day CVs were from 1.12% to 1.46%. The time for each injection is one minute. Because the proposed method can be readily carried out on increasingly popular instruments for Ru(bpy)(3)(2+) ECL immunoassays and DNA probe assays, Ru(bpy)32+ ECL method is suitable for routine clinical analysis of calcium.

Sol-gel-derived, polishable, 1 : 12-phosphomolybdic acid-modified ceramic-carbon electrode and its electrocatalytic oxidation of ascorbic acid

Novel ceramic-carbon electrodes (CCEs) containing 1:12-phosphomolybdic acid (PMo12) were constructed by homogeneously dispersing PMo12 and graphite powder into methyltrimethoxysilane-derived gel. Peak currents for the PMo12-doped CCE were surface-controlled at lower scan rates but diffusion-controlled at higher scan rates and peak potentials shifted to the negative potential direction with increasing pH. In addition, the electrode exhibited electrocatalytic activity toward the oxidation of ascorbic acid. The PMo12-modified CCE presented good chemical and mechanical stability and good surface renewability (ten successive polishing resulted in less than 5% relative standard deviation). (C) 2000 Elsevier Science B.V. All rights reserved.

LB multilayers and superlattice films of erbium fatty acid salts

Multilayers of Y-type bilayers of pure and mixed erbium palmitate(EP), nonadecanate(Er) and behenate(EB) on CaF2 substrates were prepared by conventional Langmuir-Blodgett (LB) method. II is demonstrated that two systems composed of alternating bilayer of different fatty acid salts are unidimensional superlattices. These LB films were characterized by means of x-ray photoelectronic Spectrometry (XPS), FTIR and x-ray diffraction (XRD) measurements.

Preparation of a composite film electrode containing 12-tungstosilicic acid and its electrocatalytic reduction for nitrite

A novel organic-inorganic composite film was formed by attaching Keegin-type heteropolyanion, SiW12O404- (devoted briefly as SiW12), on a glassy carbon electrode derivatized by 4-aminophenyl group. The composite film has an ionic bonding character between SiW12 and the surface amino group, which greatly improves the Blm stability and exhibits a more reversible electrochemical behavior. The modified electrode offers an excellent and stable electrocatalytic response for the reduction of nitrite. Possible mechanism was provided for the reaction of nitrite with SiW12O404-/aminophenyl composite film.

COMPARATIVE-ANALYSIS OF GLYCOPROTEIN AND GLYCOLIPID COMPOSITION OF VIRULENT AND AVIRULENT STRAIN MEMBRANES OF MYCOPLASMA-HYOPNEUMONIAE

The glycoproteins and glycolipids from membranes of virulent strain Z and avirulent strain M of Mycoplasma hyopneumoniae have been compared. The proteins and the glycoproteins were identified by SDS-polyacrylamide gel electrophoresis and concanavalin A-biotin labeling, respectively. The membrane preparation contained approximately 34 protein bands with molecular weights between 20 KD and 100 KD. The concanavalin A-biotin system reacted with a glycoprotein of a molecular weight of approximately 28,000 from avirulent strain M and did not react with the correspondent band from virulent strain Z. The membrane glycolipids of both strains consisted of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), and the percentages of 16:0, 18:0, and 18:1 fatty acids comprised more than 80% of the total fatty acids of membrane glycolipids. The 18:0 fatty acid of MGDG in avirulent strain M was twofold higher than that of virulent strain Z.

Organic geochemical studies of sinking particulate material in China sea area(I) - Organic matter fluxes and distributional features of hydrocarbon compounds and fatty acids

Sinking particulate material collected from Nansha Yongshu reef lagoon and the continental shelf of the East China Sea by sediment traps has been analyzed and studied for the first time using organic geochemical method. The results show that about half of the sinking particulate organic matter in the two study areas are consumed before reaching the depth of 5 m to the sea floor and the degree of this consumption in Yongshu reef lagoon is larger than that in the continental shelf of the East China Sea. The distributions of hydrocarbons and fatty acids indicate that the minor difference of biological sources of sinking particulate organic matter exists between Yongshu reel lagoon and the continental shelf of the East China Sea, but they mainly come from marine plankton. Stronger biological and biochemical transformations of sinking particulate organic matter are also observed and the intensity of this transformation in Yongshu reef lagoon is greater than that in the continental shelf of the East China Sea. It is found that the occurrence of C-25 highly branched isoprenoid (HBI) diene may be related to the composition of diatom species.

CHINESE NITRARIA TANGUTORUM BOBR。： CHEMICAL CONSTITUENTS OF SEED OIL EXTRACTED BY SFE-CO_2

In order to develop and make good use of Nitraria tangutorum Bobr. in Qinghai-Tibetan Plateau for its ecological and medicinal values, the seed oil was extracted by SFE-CQ2 and the chemical constituents was analyzed by GC/MS. The component relative contents were determined by area nomalization. 28 components were separated from the extracts of SFE-CQj and 12 of them, which accounted for 85.99% were identified. They were(Z, Z)-9, 12-octadecadienoic acid (linoleic acid), bicyclo[ 10. 1. 0] tridec-1-ene, 7-pentadecyne, gamma-sitosterol, gamma-tocopherol, 1, -8,Z-10-hexadecatriene,9,12-octadecadienal, 24-methyl-5-cholestene-3-ol,(Z)-9,17-octadecadienal, stigmastan-3,5-dien, eicosane and so on. Among them, the relative content of (Z, Z)-9,12-octadecadienoic acid is the highest, accounting for 65.85% of the total area. It is concluded that N. tangutorum Bobr. seed oil is a rich source of linoleic acid.

Determination of alcohols by high-performance liquid chromatography with fluorimetric detection after pre-column derivatisation with carbazole-9-N-acetic acid and chromatographic behaviour of alcoholic derivatives

Alcohols were derivatised to their carbazole-9-N-acetic acid (CRA) esters with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC . HCl) as the dehydrating agent. Studies on derivatisation conditions indicated that the coupling reaction proceeded rapidly and smoothly in the presence of a base catalyst in acetonitrile to give the corresponding sensitively fluorescent derivatives. The retention behaviour of alcohol derivatives was investigated by varying mobile phase compositions (ACN-water and MeOH-water). The parameters from the equation log k'=A-BX were evaluated by retention data of derivatives using an isocratic elution with different mobile phases. The results indicated that the parameters derived allowed computation of retention factors in good agreement with experiments. At the same time, a general equation was derived that makes possible predictions of partition coefficient in binary mobile phases with different proportions of organic solvent to water based on some simple regression analysis. The LC separation for the derivatised alcohols containing higher carbon alcohols showed good reproducibility on a reversed-phase C-18 column with gradient elution. The detection limits (excitation at 335 nm, emission at 360 nm) for derivatised alcohols (signal-to-noise ratio=3:1) were in the range of 0.1-0.4 pg per injection. (C) 2001 Elsevier Science B.V. All rights reserved.

Effects of aniracetam on extracellular levels of transmitter amino acids in the hippocampus of the conscious gerbils: an intracranial microdialysis study

The effects of aniracetam on extracellular amino acid levels in the hippocampus of conscious gerbils, with or without transient cerebral ischemia/reperfusion, were measured by microdialysis and reverse phase-high performance liquid chromatography. Increased extracellular levels of aspartate and glutamate that were observed in the hippocampus of conscious gerbils during transient global forebrain ischemia were reversed by aniracetam. In contrast, the level of extracellular gamma-aminobutyric acid was increased, while taurine was maintained at a higher level than other amino acids by administration of aniracetam (100 mg/kg, p.o.) 60 min before ischemia. Further, in contrast to ischemic animals, administration of aniracetam (100 mg/kg, p.o.) enhanced the release of glutamate and aspartate in the normal gerbil hippocampus. The results suggest that these effects might be due to a partial calcium agonist activity of aniracetam, and that the effects of aniracetam on amino acid levels might be a mechanism of protection against delayed neuronal death in the ischemic hippocampus, thereby improving memory dysfunction induced by ischemia/reperfusion. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.

Effects of several organic acids on the feeding behavior of Tilapia nilotica

Automatic recording of the frequency of feeding 'bites' was used to evaluate the effects of several organic acids (citric, metacectonic, lactic, acetic, and oxalic) on the stimulatory feeding behavior of Tilapia nilotica . Some of these acids are added to food stocks to retard spoilage. The results showed that citric acid at a concentration of 10(-2) to 10(-6) m, metacetonic acid at 10(-4) to 10(-6) m, and lactic acid at 10(-2) to 10(-5) m stimulated feeding. Fish tended to avoid metacetonic acid at 10(-3) m and acetic acid at 10(-3) m. Acetic acid at 10(-5) m and oxalic acid at 10(-6) m had no significant effects on fish feeding.

EFFECT OF TOTAL HYDROGEN CONTENT IN SILICON-NITRIDE SENSITIVE FILM ON PERFORMANCE OF ISFET

Quantitative determinations of the hydrogen content and its profile in silicon nitride sensitive films by the method of resonant nuclear reaction have been carried out. At a deposition temperature of 825-degrees-C, hydrogen exists in an LPCVD silicon nitride sensitive film and the hydrogen content on its surface is in the range (8-16) x 10(21) cm-3, depending on the different deposition processes used. This hydrogen content is larger than the (2-3) x 10(21) cm-3 in its interior part, which is homogeneous. Meanwhile, we observe separate peaks for the chemical bonding configurations of Si-H and N-H bonds, indicated by the infrared absorption bands Si-O (1106 cm-1), N-H (1200 cm-1), Si-H-3 (2258 cm-1) and N-H-2 (3349 cm-1), respectively. The worse linear range of the ISFET is caused by the presence of oxygen on the surface of the silicon nitride sensitive film. The existence of chemical bonding configurations of Si-H, N-H and N-Si on its surfaces is favourable for its pH response.