Quantitative determination of 3-methoxy-4-hydroxy-mandelic acid (VMA) in urine.
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A bioluminescence assay for bile acids was developed using a co-immobilized 3 alpha-hydroxysteroid dehydrogenase, diaphorase, and bacterial luciferase. The assay was specific for bile acids containing a free 3 alpha-hydroxyl group, as well as androsterone. Light output was linear over a bile acid concentration range of 1-20 000 pmol. Intra-assay precision was 6.2-8.2% and the recovery of added standards was 92-110%. Comparison of results using the bioluminescence assay with those using gas liquid chromatography revealed an excellent correlation (r = 0.99, n = 31). Since the bioluminescence assay is rapid, sensitive, specific, and uses inexpensive reagents, it appears to be an ideal method for the measurement of total bile acids in serum.
Various aromatic acids have been investigated as putative ligands of excitatory amino acid receptors. 3-Hydroxy-2-quinoxalinecarboxylic acid (HQC), at 1 mM, was found to antagonize the 22Na+ efflux produced in 22Na+-preloaded brain slices by N-methyl-D-aspartate and kainate. The response to glutamate was also affected but not that to quisqualate. The apparent KI value of HQC for suppression of the N-methyl-D-aspartate response was 0.27 mM. The anticonvulsant action of HQC was investigated in mice and rats. HQC administered intracerebroventricularly caused a dose dependent delay in the occurrence of picrotoxin induced convulsions and afforded protection against picrotoxin induced death. These results confirm the proposition that antagonists of excitatory amino acids possess anticonvulsant properties.
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The presence of polymorphonuclear leukocytes (PMNs) within the airways is a characteristic feature of a variety of lung diseases. Pulmonary alveolar macrophages (PAMs) and epithelial cells release many different factors which contribute to the recruitment of inflammatory cells into infected airways. PAMs and tracheal epithelial cells are able to produce linoleic acid metabolites (9-HODE and 13-HODE) besides arachidonic acid metabolites. The objective of the present study was to determine whether 9-HODE and 13-HODE possess chemotactic activity for isolated PMNs. It was found that 9-HODE and 13-HODE induced a chemotactic response of both human and bovine PMNs in vitro. The HODEs evoked chemotaxis with a linear dose response from 10(-10) to 10(-6) M to the same extent as the arachidonic acid metabolite 15-HETE. At 10(-8) M, 9-HODE and 13-HODE were approximately half as potent in inducing chemotaxis as compared to LTB4.
Various diarylheptanoids including curcumin, bis (3,4-dihydroxy-cinnamoyl) methane, and yakuchinones A & B were screened and found to be potent inhibitors of 5-HETE production by intact human neutrophils, with respective IC50 values of 8.0, 4.4, 5.4, and 4.0 microM. These diarylheptanoids were found to be more potent than BW-755C, Phenidone, and AA-861. We have confirmed a previous report that several of these diarylheptanoids inhibit cyclooxygenase. Thus, curcuminoids and yakuchinones are more accurately characterized as dual inhibitors of arachidonic acid metabolism.
A new rapid high-performance liquid chromatographic method, without urine sample pre-treatment and based on isocratic ion-pair elution, fluorimetric detection and column-switching, has been developed for the determination of vanillylmandelic acid. The sensitivity was 0.1 mg/l, and the linearity was excellent in the concentration range tested. For all endogenous substances as well as for all the drugs tested no interferences were observed. Typical concentrations were in the range 0.3-5.5 mg of vanillylmandelic acid per day, depending on the age of subject under investigation.
99mTc complexes of 2-ethyl-2-hydrobutyric acid, 2-hydroxyisobutyric acid and (+)- and (-)-citramalic acid are readily prepared in high yield and high purity by reduction of 99mTcO4- in the presence of excess ligand. The resulting agents are very stable in vitro, but can undergo some decomposition during chromatographic analysis unless appropriate precautions are taken. Biodistribution studies in rats and dogs show that these new 99mTc agents accumulate primarily in the kidney and urinary bladder.