ABSTRACT
A procedure for the quantification of sub-nanogram per millilitre concentrations of indomethacin in plasma and synovial fluid has been developed using gas chromatography/negative ion chemical ionization/tandem mass spectrometry. The procedure is based on selected ion monitoring of the daughter ion at m/z 312 generated following decarboxylation of the 35Cl isotope peak of the indomethacin anion (m/z 356) formed from the pentafluorobenzyl ester of indomethacin in the ion source of the mass spectrometer. The internal standard, d2-indomethacin, has a daughter ion at m/z 316 formed from the corresponding 37Cl isotope peak. The limit of quantification was 0.1 ng ml-1 for both plasma and synovial fluid.
Subject(s)
Indomethacin/chemistry , Synovial Fluid/chemistry , Chlorine , Gas Chromatography-Mass Spectrometry , Humans , Indomethacin/blood , RadioisotopesABSTRACT
The effect of methanol on the ability of elicited rat peritoneal leukocytes to metabolise endogenous and exogenous arachidonic acid was studied using 2H8-arachidonic acid as the source of exogenous arachidonic acid and calcium ionophore A23187 as the lipoxygenase stimulus. As the methanol concentration increased from 0 to 992 mM there was a slight decrease in the total amount of LTB4 and related compounds formed, however examination of the ratio of undeuterated to deuterated LTB4 formed revealed that as the methanol concentration increased from 0 to 992 mM, the percentage of undeuterated LTB4 present decreased significantly from 57 +/- 9% to 2 +/- 1%. Methanol interferes with the ability of these cells to utilise endogenous arachidonic acid even in the presence of the powerful stimulus calcium ionophore A23187 thus allowing the facile biosynthesis of a range of deuterium labelled arachidonic acid metabolites.
Subject(s)
Arachidonic Acids/metabolism , Leukocytes/metabolism , Methanol/pharmacology , Animals , Arachidonic Acid , Arachidonic Acids/pharmacology , Calcimycin/pharmacology , Depression, Chemical , Enzyme Activation/drug effects , Gas Chromatography-Mass Spectrometry , Leukocytes/drug effects , Leukotriene B4/biosynthesis , Lipoxygenase/metabolism , Peritoneal Cavity/cytology , RatsABSTRACT
A procedure for the quantification of leukotriene B4 (LTB4) in synovial fluid has been developed using gas chromatography/tandem mass spectrometry based on selected reaction monitoring of the elimination of t-butyldimethylsilanol from the ions of m/z 431 and 438 in the negative ion chemical ionization mass spectra of the di-t-butyldimethylsilyl/pentafluorobenzyl derivatives of leukotriene B4 and the internal standard (2H8)leukotriene B4. The detection limit (approximately 10 pg ml-1) is sufficiently low to permit determination of LTB4 concentration in the synovial fluid of patients with various arthropathies. Single-stage mass spectrometry was found not to be selective enough to permit quantification of LTB4 in synovial fluid.
Subject(s)
Gas Chromatography-Mass Spectrometry/methods , Leukotriene B4/analysis , Synovial Fluid/analysis , Arthritis, Rheumatoid/metabolism , Humans , Osteoarthritis/metabolismABSTRACT
Plasma and synovial fluid concentrations of biphenylacetic acid were determined following application of 3 g of 3% biphenylacetic acid gel to one knee of patients suffering from rheumatoid arthritis. The mean peak plasma concentration was 34 ng/ml. Synovial fluid concentrations tended to follow plasma concentrations but at a somewhat lower level, the mean peak synovial fluid concentration was 21 ng/ml. The average ratio of synovial fluid AUC (0-24 h) to plasma AUC (0-24 h) was 0.58, r = 0.97. Where patients had bilateral effusions, the concentration in the ipsilateral knee at each time point examined was not significantly different to that in the contralateral knee, suggesting that absorption was initially into the plasma and subsequently into the synovium.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/administration & dosage , Phenylacetates/administration & dosage , Administration, Topical , Adult , Aged , Anti-Inflammatory Agents, Non-Steroidal/pharmacokinetics , Female , Humans , Male , Middle Aged , Phenylacetates/pharmacokineticsABSTRACT
The activities of α-mannosidase (EC 3.2.1.24), ß-galactosidase (EC 3.2.1.23), and α-galactosidase (EC 3.2.1.22) have been measured in extracts from cotyledons at various stages following germination of pea seeds (Pisum sativum L., cultivars Melbourne Market, Greenfeast, and Telephone). The activities of all three glycosidases are fully accounted for by enzyme synthesis during seed development. The α-mannosidase (isoenzyme 1) from pea cotrledons is inhibited by the indolizidine alkaloid swainsonine with an apparent K(i) of 1.37 \sx 10(-7) M.
