Monitoring the aggregation processes of amyloid-β using a spin-labeled, fluorescent nitroxyl radical

Amyloid nitroxyl radical (nitroxide) ligands were used to detect amyloid-β fibrils, the main constituents of senile plaques in Alzheimer's disease, using anisotropic ESR spectra, and were found to affect the aggregation process due to the radical functionality. These compounds have great potential as novel and multifunctional probes, combining spin labels, spin probes, and fluorescence probes.     

Fluorescent trimethyl-substituted naphthyridine as a ligand for C-C mismatch detection in CCG trinucleotide repeats

We report on the selective binding of 2-amino-5,6,7-trimethyl-1,8-naphthyridine (ATMND) to C-C mismatch present in the hairpin structures of (CCG)(n) trinucleotide repeats that are associated with neurological diseases; this binding is accompanied by significant fluorescence quenching of ATMND.     

Inhibitory effects of constituents from Euphorbia lunulata on differentiation of 3T3-L1 cells and nitric oxide production in RAW264.7 cells

A new flavonol galactopyranoside, myricetin 3-O-(2',3'-digalloyl)-β-D-galactopyranoide (1), and 23 known constituents, including myricetin 3-O-(2'-galloyl)-β-D-galactopyranoide (2), myricitrin (3), myricetin (4), quercetin 3-O-(2', 3'-digalloyl)-β-D-galactopyranoide (5), quercetin 3-O-(2'-galloyl)-β-D-galactopyranoide (6), hyperin (7), isoquercetrin (8), quercetin (9), kaempferol (10), apigenin (11), luteolin (12), 3-O-methylquercetin (13), 5,7,2',5'-tetrahydroxyflavone (14), 1,3,4,6-tetra-O-galloyl-β-D-glucose (15), 1,2,6-tri-O-galloyl-β-D-glucose (16), 1,3,6-tri-O-galloyl-β-D-glucose (17), gallic acid (18), protocatechuic acid (19), 3,4,5-trimethoxybenzoic acid (20), 2,6-dihydroxyacetophenone (21), 3,3'-di-O-methylellagic acid (22), ellagic acid (23) and esculetin (24) were isolated from Euphorbia lunulata Bge. Their structures were determined by spectroscopic analysis. Isolated hydrolysable tannins, flavonoids, and flavonol galactopyranoside gallates showed significant inhibition of the differentiation of 3T3-L1 preadipocytes and triglyceride accumulation in maturing adipocytes, and nitric oxide production in RAW 264.7 cells.     

Magnetic evaluation of intergranular interactions in thin-film media by rotational hysteresis loss analysis

Magnetic torque analysis has been carried out for CoNiPt, CoCrTa/Cr and CoCrPt/Cr thin-film media. The magnetic field H^grain_k, where the rotational hysteresis loss vanishes, remained almost constant in each material, independent of the coercive force H_c. Only in the CoCrTa media no clear correlation between the rotational hysteresis integral and H_c was observed.     

Application of a novel large-volume injection method using a stomach-shaped inlet liner in capillary gas chromatographic trace analysis of dioxins in human milk and plasma.

A newly developed large-volume injection (LVI) technique that employs a unique stomach-shaped inlet liner (SSIL) inside of a programmable temperature vaporizer was used for the determination of trace amounts of dioxins in human milk and plasma. The initial temperature and the initial dwelling time of the inlet and the kind of solvent used were found to be critical in determining the analytical sensitivity of dioxins due to the loss of these relatively volatile compounds during solvent vaporization. Human milk and plasma were purified and fractionated by pre-packed multi-layered silica-gel chromatography and activated carbon silica-gel column chromatography. A 20-microL aliquot of the fraction collected from the chromatography with toluene was directly applied to the LVI system in high-resolution gas chromatography/high-resolution mass spectrometry. Excellent correlation (r > 0.97) between the values obtained by the LVI method using the SSIL device and those by the conventional regular-volume splitless injection method was obtained for PCDDs, PCDFs and non-ortho PCBs in human milk and plasma samples.     

Sensitive derivatizatton reagents for the resolution of carboxylic acid enantiomers by high-performance liquid chromatography

Two highly sensitive, chiral derivatization reagents, D- and L-1-aminoethyl-4-dimethyl-aminonaphthalene, were synthesized from 1-dimethylaminonaphthalene. Condensation of carboxylic acids with the chiral reagent was readily effected in the presence of a watersoluble carbodiimide. The diastereoisomeric amides formed from N-acetylamino acid and α-arylpropionic acid enantiomers were efficiently resolved by normal phase chromatography (μPorasil column) -with hexane/ethyl acetate or hexane/tetrahydrofuran as a mobile phase. With a fluorescence detector (excitation 320 nm, emission 395 nm), the detection limit was 0.1 ng.