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Biomedical subjects

H Gleispach

Publications and source records attributed to H Gleispach.

At least 37 records · Page 2Linked to original sources
PubMed1988

Femtomole analysis of diclofenac in human plasma by gas chromatography/negative ion chemical ionization mass spectrometry using (18O2) diclofenac as internal standard.

A stable isotope dilution gas chromatographic/negative ion chemical ionization mass spectrometric assay for diclofenac in human plasma is described. The preparation of (18O2)diclofenac and its use as an internal standard for quantitative gas chromatography/mass spectrometry is shown. A sample processing and derivatization sequence with product recovery of 84.7% was found. The method presented permits quantitative measurement of diclofenac in human plasma at the lower femtomole level. Plasma levels of diclofenac after administration of diclofenac gel were estimated.

Diclofenac↗
PubMed1988

Anticoagulation for continuous arteriovenous hemofiltration in children.

Continuous arteriovenous hemofiltration requires continuous anticoagulation to prevent early hemofilter clotting. We used heparin given continuously in the arterial line of the extracorporeal circuit as anticoagulant in children with initially normal coagulation status, and heparin and/or prostacyclin in high-risk bleeding patients with preexisting coagulopathy. Heparin infusion enabled a mean running time of 22.2 +/- 9.6 h, with the 0.1-m2 hemofilter and of 26.6 +/- 4.7 h with the 0.25-m2 hemofilter. The mean filter running time with combined heparin/prostacyclin infusion was 31 +/- 8.8 h. Prostacyclin as the sole antithrombotic agent provided good filter function only in 1 patient with preexisting coagulopathy. No adverse effects such as bleeding thrombosis, or hypotension were observed.

Anticoagulants↗
PubMed1988

Comparison of the inhibitory effect of nonsteroidal antiinflammatory drugs on bone prostaglandin synthesis and resorption.

The biopotency of various nonsteroidal antiinflammatory drugs (NSAID) in inhibiting prostaglandin (PG) mediated bone resorption was evaluated in a neonatal mouse calvaria organ culture system. Thrombin stimulated formation of the osteolytic PG, PGE2 and PGI2 (measured as 6-keto-PGF1 alpha) and the concomitant stimulation of calcium release from cultured bone were inhibited by diclofenac much greater than indomethacin much greater than flurbiprofen greater than piroxicam greater than acemetacin much greater than acetylsalicylic acid. The relative potencies of the NSAID on PG synthesis in bone differs from that observed previously in other model systems.

Animals↗
PubMed1987

Quantitative measurement of 5-, 12-, and 15-hydroxyeicosatetraenoic acid together with 12-hydroxyheptadecatrienoic acid by stable isotope dilution gas chromatography-negative ion chemical ionization-mass spectrometry.

A stable isotope dilution gas chromatography-negative ion chemical ionization-mass spectrometry assay for simultaneous quantitative measurement of 5-hydroxyeicosatetraenoic acid (HETE), 12-HETE, 15-HETE, and 12-hydroxyheptadecatrienoic acid in one single GC/MS run was established. 18O2-Labeled analogs as internal standards, prepared according to conventional procedures, were found to be useful for this application. A sample processing and derivatization sequence providing highly purified compounds with a recovery of 42.7% was elaborated. The detection limit was in the femtomole range.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1987

Formation of 6,15-diketoprostaglandin F1 alpha from prostaglandin G2 by bovine aortic endothelial cells.

Besides 6-ketoprostaglandin F1 alpha, bovine aortic endothelial cells also produced considerable amounts of 6,15-diketoprostaglandin F1 alpha from arachidonic acid, either exogenously added or released from cellular phospholipids. Incubations of particulate fractions of endothelial cells with the cyclic endoperoxides prostaglandin G2 and prostaglandin H2 showed that 6,15-diketoprostaglandin F1 alpha is formed by the action of prostaglandin I2 synthetase on prostaglandin G2. The labile metabolite 15-hydroperoxyprostaglandin I2 is then converted nonenzymatically to the 15-keto derivative. In the presence of reduced glutathione, quantitative analysis of both metabolites by gas chromatography-mass spectrometry showed a significant decrease of 6,15-diketoprostaglandin F1 alpha formation, whereas prostaglandin I2 synthesis was markedly increased. This shift seems to be due to a stimulation of peroxidase by GSH, a well known cofactor of this enzyme. Thus, it seems that a decreased endothelial prostaglandin I2 formation may occur when cellular glutathione levels are reduced as a consequence of oxidant injury and lipid peroxidation. Additionally, ferrous ions seems to be involved in the regulation of endothelial prostaglandin I2 synthesis, since Desferal, a specific ferrous ion chelator that might have antimetastatic properties, produced a pronounced shift from 6,15-diketoprostaglandin F1 alpha to the 6-keto derivative, i.e., prostaglandin I2.

6-Ketoprostaglandin F1 alpha↗
PubMed1987

Gamma interferon inhibits basal and interleukin 1-induced prostaglandin production and bone resorption in neonatal mouse calvaria.

Production of the osteolytic arachidonic acid metabolites, prostaglandin (PG) E2, PGI2 and PGF2 alpha, by neonatal mouse calvariae was quantitated by gas chromatography/mass spectrometry. Mouse recombinant interleukin 1 (rIL-1) raised medium levels of PGE2 and PGI2 (measured as 6-keto-PGF1 alpha) in the dose range tested (1.0-10.0 U/ml culture medium), while an effect on PGF2 was only observed at 10 U/ml. Bone resorption in response to rIL-1 reached a plateau at 3.0 U/ml. Mouse recombinant gamma-interferon (rIFN-gamma) between 100-500 U/ml suppressed basal PG synthesis and spontaneous resorption of cultured bone. In addition, IFN-gamma at 100 U/ml prevented stimulation of PG synthesis by 3.0 U/ml rIL-1 and thereby reduced the bone resorbing activity of the cytokine by at least 60%. 5 X 10(-7) M indomethacin was equally effective in suppression of PG synthesis and bone resorption. The present study provides evidence that IFN-gamma inhibits PG synthesis and consequently resorption of cultured bone.

Animals↗
PubMed1987

Measurement of prostaglandins, thromboxanes and hydroxy fatty acids by stable isotope dilution gas chromatography/mass spectrometry.

A method for measurement of PGF2 alpha, PGE1, PGE2, 6-keto-PGF1 alpha, TXB2, 2,3-dinor-TXB2 as well as 5-, 8-, 9-, 11-, 12-, 15-HETE and HHT, utilizing negative ion chemical ionization GC/MS is presented. A highly efficient separation and purification procedure prior to the derivatization sequence allows quantification of the arachidonic acid metabolites described in two GC/MS runs. The detection limit was in the femtomole range. Application of the method to the quantitative profiling of arachidonic acid metabolites in various tissues and incubation media is demonstrated.

Gas Chromatography-Mass Spectrometry↗
PubMed1987

Cyclooxygenase and lipoxygenase metabolites during platelet aggregation: quantitative measurement by negative ion chemical ionization--gas chromatography/mass spectrometry.

This study was aimed at investigating systematically the aggregation of human gel filtered platelets induced by various physiological stimuli such as thrombin (0.25 U/ml), collagen (2 micrograms/ml), a mixture of thrombin and collagen, and ADP (2-5 microM). For quantitative measurement of TXB2, PGF2 alpha and 12-HETE, negative ion chemical ionization-gas chromatography/mass spectrometry using stable isotope dilution was applied. Stimulation by thrombin, collagen and the combined agonists resulted in an increase of TXB2 (up to 54 ng/1 X 10(8) platelets) and 12-HETE (up to 44 ng/1 X 10(8) platelets) during platelet aggregation. The stimulation with ADP showed only little increase of these metabolites and this only during the second wave of aggregation. Very little amounts of PGF2 alpha were produced during thrombin stimulated aggregation.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1987

Long-term adrenergic beta-action decreases and alpha-action enhances corticosterone levels in rats.

A 20 h hyperadrenalinemia in rats was produced by subcutaneously implanted A-retard tablets with an output rate of 1.8 micrograms/min/250 g. This caused a moderate (6 h, 20 h) to expressed (12 h) rise in Corticosterone. Concomitant beta-blockade leads to equal (12 h, 20 h) or even more expressed (6 h) enhancement of plasma corticosterone, while A + alpha-blockade lowers those levels significantly against A or A + Prop treated animals. At 6 and 20 h they are even significantly lower than control values. We therefore conclude that enhanced alpha-adrenergic influence increases and beta-adrenergic influence decreases plasma Corticosterone levels in rats.

Adrenocorticotropic Hormone↗
PubMed1986

Possible inhibitory function of endogenous 15-hydroperoxyeicosatetraenoic acid on prostacyclin formation in bovine aortic endothelial cells.

Arachidonic acid is metabolized via the cyclooxygenase pathway to several potent compounds that regulate important physiological functions in the cardiovascular system. The proaggregatory and vasoconstrictive thromboxane A2 produced by platelets is opposed in vivo by the antiaggregatory and vasodilating activity of prostacyclin (prostaglandin I2) synthesized by blood vessels. Furthermore, arachidonic acid is metabolized by lipoxygenase enzymes to different isomeric hydroxyeicosatetraenoic acids (HETE's). This metabolic pathway of arachidonic acid was studied in detail in endothelial cells obtained from bovine aortae. It was found that this tissue produced 6-ketoprostaglandin F1 alpha as a major cyclooxygenase metabolite of arachidonic acid, whereas prostaglandins F2 alpha and E2 were synthesized only in small amounts. The monohydroxy fatty acids formed were identified as 15-HETE, 5-HETE, 11-HETE and 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT). The latter two compounds were produced by cyclooxygenase activity. Nordihydroguaiaretic acid (NDGA), a rather selective lipoxygenase inhibitor and antioxidant blocked the synthesis of 15- and 5-HETE. It also strongly stimulated the cyclooxygenase pathway, and particularly the formation of prostacyclin. This could indicate that NDGA might exert its effect on prostacyclin levels by preventing the synthesis of 15-hydroperoxyeicosatetraenoic acid (15-HPETE), a potent inhibitor of prostacyclin synthetase. 15-HPETE could therefore act as an endogenous inhibitor of prostacyclin production in the vessel wall.

Animals↗
PubMed1986

Preparation of 18O-labelled standards of hydroxy-eicosatetraenoic acids and thromboxanes for quantitative measurement by gas chromatography/mass spectrometry.

A study on the extent of 18O incorporation into various hydroxy-eicosatetraenoic acids, thromboxane B2 and 2,3-dinor-thromboxane B2 by base-catalysed hydrolysis of their methyl ester derivatives is presented. The amount as well as the position of the inbuilt 18O atoms were determined by gas chromatography/mass spectrometry, utilizing electron impact and positive and negative ion chemical ionization.

Gas Chromatography-Mass Spectrometry↗
PubMed1985

Qualitative and quantitative measurement of hydroxy fatty acids, thromboxanes and prostaglandins using stable isotope dilutions and detection by gas chromatography-mass spectrometry.

Methods for measurement of the metabolites of arachidonic acid (AA), namely prostaglandins (PGs), thromboxanes (TXs) and hydroxy fatty acids, using stable isotope dilution gas chromatography--mass spectrometry are described. With a few exceptions, labelled species of the various AA metabolites are not commercially available and were therefore synthesized in our laboratory. [2H8]AA, produced by deuteration of eicosatetraynoic acid, was used for comparing the metabolism of exogenously added and endogenously present AA in fibroblast cultures. After derivatization and catalytic hydrogenation, structure elucidation and quantification of the different hydroxy fatty acids was carried out by determination of the fragment ions resulting from alpha-cleavage at the site of the hydroxy function. During catalytic hydrogenation a significant hydrogen--deuterium exchange was observed. To eliminate this problem, 18O-labelled standards were prepared by exchanging the oxygen of the carboxylic acid group. The preparation and the use of hydroxy fatty acids, PGs and TXs labelled with 18O is described.

Fatty Acids↗
PubMed1984

Characterization of lipoxygenase metabolites of arachidonic acid in cultured human skin fibroblasts.

Cultured human skin fibroblasts were incubated in the presence of [14C]arachidonic acid (50 microM; 1 m Ci/mmol) and the divalent cation ionophore A23187 at 37 degrees C for 60 min. The metabolites formed were extracted from the cell-free medium in diethyl ether, separated by thin layer chromatography and identified unequivocally by GC-MS. The distribution of the arachidonic acid metabolites as estimated from the recovered radioactivity showed as major product prostaglandin E2 (26%). Minor amounts of other prostaglandins, i.e., 6-oxo-prostaglandin F1 alpha (1%), prostaglandin F2 alpha (1%), prostaglandin D2 (0.5%) and prostaglandin A2 (1%) were also present. In addition to the prostaglandins, monohydroxy fatty acids (4.5%) were also detected. This fraction contained 33% 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT), 22% 11-hydroxy-5,8,11,14-eicosatetraenoic acid (11-HETE) and 31% 15-hydroxy-5,8,11,13-eicosatetraenoic acid (15-HETE). Lipid extracts of the cells did not show any detectable amount of the monohydroxy fatty acids, indicating that they are not incorporated metabolically in the cellular lipids. The monohydroxy fatty acids originate mainly from the exogenously added arachidonic acid as evidenced by the 2H/H ratio (30:1) from experiments with octadeuterated arachidonic acid [( 2H8]arachidonic acid). Indomethacin inhibited the formation of all prostaglandins, HHT and 11-HETE; moreover, eicosatetraynoic acid (also blocked the formation of 15-HETE. From these results, it can be concluded that in human skin fibroblasts prostaglandin E2 is the major product of the cycloxygenase pathway, while 15-HETE is the main lipoxygenase product.

Arachidonic Acid↗