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Biomedical subjects

P Ney

Publications and source records attributed to P Ney.

At least 19 recordsLinked to original sources
PubMed1991

PGD2 and its mimetic ZK 110.841 are potent inhibitors of receptor-mediated activation of human neutrophils.

The action of PGD2 and its mimetic ZK 110.841 ((5Z,13E)-(9R,11R,15S)-9-chloro-15-cyclohexyl-11,15- dihydroxy-16,17,18,19, 20-pentanor-5,13-prostadienoic acid) was compared to PGE1 in vitro on superoxide anion generation, degranulation, leukotriene (LT) B4 release and Ca++ fluxes in human polymorphonuclear leukocytes (PMN). All compounds were potent inhibitors of formyl-methionyl-leucyl-phenylalanine (FMLP)- and platelet-activating factor (PAF)-induced superoxide anion generation, beta-glucuronidase release and Ca++ influx. The PAF-induced release of LTB4 in the presence of 10 mumoles/l arachidonic acid was significantly attenuated by these prostaglandins. This inhibition of PMN function was paralleled by an increase in cellular cAMP levels. The molar potency of the prostaglandins used was comparable, although the D-type compounds appeared slightly more potent in some PMN function tests. None of the substances affected PMN activation induced by the calcium inophore calcimycin (A23187). The data demonstrate an effective inhibition of receptor-mediated (FMLP, PAF) PMN activation by PGD2 and its mimetic ZK 110.841, suggesting either an inhibitory PGD2 receptor on human PMN or action of PGD2 at the PGE receptor. PGD2 is a labile compound in vivo and is rapidly metabolized into a number of products with different biological properties. Since ZK 110.841 lacks this instability, this compound may serve as an important tool to classify PGD2-mediated reactions.

Alprostadil↗
PubMed1991

Antiplatelet, antineutrophil and vasodilating properties of 13,14-dihydro-PGE1 (PGE0)--an in vivo metabolite of PGE1 in man.

The actions of the in vivo metabolite of PGE1, 13,14-dihydro-PGE1 (PGE0), on platelet and neutrophil (PMN) function and vessel tone were studied in vitro. PGE0 inhibited aggregation, ATP release and thromboxane generation by human platelets (IC50 10-100 nmoles/l). The compound also inhibited superoxide anion generation and lysosomal enzyme release from human PMN. PGE0 was equipotent to PGE1 in both systems, while 15-keto-PGE1 was ineffective in platelets but produced some inhibition in PMN. These inhibitory effects of PGE0 and PGE1 were paralleled by concentration-dependent increases in cyclic AMP in platelets and PMN. Both compounds were also potent relaxants of several arterial preparations in the rabbit at comparable concentrations. In general, the vasorelaxing properties of PGE0 were somewhat lower and the contractile effects somewhat stronger in comparison to PGE1. These data demonstrate a significant and concentration-dependent inhibition of receptor-mediated activation of human platelets and PMN by PGE0. The molar potency of the compound is comparable to that of PGE1. Generation of PGE0 from infused PGE1 may contribute to the clinical efficacy of PGE1 in treatment of severe peripheral arterial occlusive disease.

Alprostadil↗
PubMed1991

[The pharmacology of 13,14-dihydro-PGE1 in comparison with PGE1].

This study investigates the effects of 13,14-Dihydro-PGE1 (PGE0) in comparison to PGE1 on human platelets, human polymorphonuclear granulocytes (PMN) and a number of vessel preparations of different species. The potency of PGE0 in inhibition of platelet and neutrophil activation is similar to PGE1. The vascular action differs. At a comparable molar potency, PGE0 showed stronger contractile and less relaxing effects than PGE1. The biological activities of PGE0 may contribute to the in vivo effects of PGE1 in treatment of peripheral arterial occlusive disease, in particular at high-dose i.v. administration.

Alprostadil↗
PubMed1990

Cyclic GMP mediates SIN-1-induced inhibition of human polymorphonuclear leukocytes.

Different nitrovasodilators were used to assess the role of cyclic GMP in the regulation of polymorphonuclear leukocyte (PMN) function. Molsidomine and its metabolites, 3-morpholinosydnonimine (SIN-1) and N-nitroso-N-morpholinoaminoacetonitrile (SIN-1A) at 0.01-1 mM, inhibited lysosomal enzyme release from PMN stimulated by 30 nM formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP). At 1 mM, molsidomine, SIN-1 and SIN-1A decreased beta-glucuronidase release by 19, 37 and 46% of the control, respectively. Glyceryl trinitrate (GTN) and sodium nitroprusside (SNP) showed no effect on beta-glucuronidase release from PMN. At 1 mM, SIN-1A, SIN-1 and SNP in the presence of 0.5 mM isobutylmethylxanthine (IBMX) stimulated cyclic GMP 21-, 9- and 14-fold, respectively, demonstrating a relation between cyclic GMP stimulation and neutrophil inhibition by the molsidomine metabolites. GTN and unmetabolized molsidomine were without effect on cyclic GMP levels. The hypothesis of an inhibitory effect of cyclic GMP on neutrophil function was further supported by the attenuation of SIN-1-induced inhibition of enzyme release by methylene blue (10 microM), an inhibitor of soluble guanylate cyclase. Moreover, 8-bromo cyclic GMP and dibutyryl cyclic GMP, 1 mM, decreased beta-glucuronidase release from FMLP-stimulated PMN by 12 and 44% of the control, respectively. These data demonstrate that cyclic GMP is an inhibitory second messenger in human PMN and suggest that this action of SIN-1 may be of considerable interest under conditions of platelet/PMN activation, e.g. during myocardial ischemia.

1-Methyl-3-isobutylxanthine↗
PubMed1990

A 46 base pair enhancer sequence within the locus activating region is required for induced expression of the gamma-globin gene during erythroid differentiation.

The locus activating region (LAR), contained within 30 kb of chromatin flanking the human beta-globin gene cluster, has recently been shown to be essential for high level beta-globin gene expression. To determine the effect of fragments containing LAR sequences on globin gene expression, mRNA from a marked gamma-globin gene linked to LAR fragments was assayed in stably transfected K562 erythroleukemia cells. DNaseI hypersensitive site II (HS II), located 10.9 kb upstream of the epsilon-globin gene, was required for high level gamma-globin gene expression. We also showed that a 46 bp enhancer element within HS II was necessary and sufficient for the increased gamma-globin gene expression observed with hemin induced erythroid maturation of K562 cells. These results localize a distant regulatory element important for activation of globin genes during human erythroid cell maturation.

Base Sequence↗
PubMed1990

Cytotoxic enzyme release and oxygen centered radical formation in human neutrophils are selectively inhibited by E-type prostaglandins but not by PGI2.

The action of PGE1, PGE2, PGI2 and iloprost on superoxide anion generation, lysosomal enzyme release, and changes of Ca2+ fluxes in human polymorphonuclear leukocytes (PMN) was studied in vitro. Both PGE-type compounds were equipotent inhibitors of FMLP-and PAF-stimulated superoxide anion generation, beta-glucuronidase release (IC50 3-5 mumol/l) and Ca2+ influx while PGI2 and iloprost were ineffective at concentrations up to 10 mumol/l. These inhibitory actions of PGE1 and PGE2 were paralleled by an increase in cAMP level of the PMN while no change occurred with PGI2 and iloprost. None of the prostaglandins affected the initial intracellular Ca2+ liberation after challenge with FMLP or PAF. Preincubation of PMN with PGE1 and PGE2 but not with iloprost resulted in subsequent desensitization against a second administration of these compounds. None of the compounds affected PMN activation produced by arachidonic acid or calcimycin (A 23187). These data demonstrate that PGE-type compounds are effective inhibitors of receptor-mediated (PAF, FMLP) activation of human PMN while prostacyclins are considerably less potent. This suggests that the inhibitory prostaglandin receptor on human PMN belongs to the E-type being functionally different from the inhibitory prostaglandin receptor on human platelets. These results suggest that compounds, such as PGE1 and PGE2 might be superior to prostacyclins to prevent PMN-associated generation of reactive oxygen species and lysosomal enzyme release in situations with endogenous PMN activation, i.e. inflammatory reactions.

Arachidonic Acid↗
PubMed1990

Nitrovasodilator-induced inhibition of LTB4 release from human PMN may be mediated by cyclic GMP.

This study investigates the action of nitrovasodilators on f-metleu-phe (FMLP)-stimulated LTB4 release and intracellular cyclic nucleotide levels in human polymorphonuclear leukocytes (PMN). Sodium nitroprusside, and the molsidomine (MOL) metabolites SIN-1 and SIN-1A potently inhibited LTB4 release and increased cGMP levels. No significant effects on LTB4 release or cGMP accumulation were observed in the presence of molsidomine or glyceryl trinitrate. None of the compounds tested affected cAMP levels. It is suggested that nitrovasodilators (i) inhibit LTB4 release from human PMN via enhanced cGMP and (ii) that this inhibition requires the presence of an active metabolite, probably nitric oxide.

Cyclic GMP↗
PubMed1989

E-type prostaglandins but not iloprost inhibit platelet activating factor-induced generation of leukotriene B4 by human polymorphonuclear leukocytes.

1. Platelet-activating factor (Paf) was found to stimulate leukotriene B4 release from human polymorphonuclear leukocytes (PMN). This stimulation was considerably enhanced in the presence of small amounts of exogenous arachidonic acid. 2. Prostaglandin E2 (PGE2) and PGE1 (0.1-10 microM) inhibited this reaction dose-dependently. No inhibition was seen with iloprost at these concentrations. 3. The data suggest that E prostaglandins are potent inhibitors of Paf-induced leukotriene generation by human PMNs and thus may serve as local factors controlling Paf-mediated inflammatory reactions.

Arachidonic Acids↗
PubMed1989

Endothelial protection by defibrotide--a new strategy for treatment of myocardial infarction?

Myocardial ischemia is associated with endothelial injury and an apparently insufficient generation of endothelium-derived vasodilating and platelet and white cell inhibitory mediators, such as prostacyclin (PGI2) and EDRF. This paper reviews some recent findings of our laboratory on cardioprotective effects of defibrotide, a PGI2 stimulating agent, in experimental myocardial ischemia and its possible sites of action in several in vitro assay systems. Defibrotide (32 mg/kg x h) reduced the infarct size by 50% in pigs, subjected to 1 h of coronary artery ligation followed by 3 h of reperfusion. This was associated with significant inhibition of neutrophil activation during the reperfusion period and a two-to threefold increase in cardiocoronary PGI2 generation. In vitro studies on PAF- and calcium ionophore-stimulated human granulocytes confirmed a dose-dependent (10-1000 micrograms/ml) antineutrophil effect of defibrotide (inhibition of lysosomal enzyme release) which was independent of the type of stimulus. Defibrotide (0.1 mg/ml) also inhibited superoxide anion generation from PAF stimulated neutrophils in Langendorff-perfused guinea pig hearts and was equipotent to a specific PAF antagonist (BN 52021). Defibrotide (0.1 mg/ml) did not stimulate PGI2 release from cultured porcine aortic endothelial cells but enhanced PGI2 release four- to fivefold above control if endothelial cells were coincubated with platelets. These data demonstrate a considerable cardioprotective potential of defibrotide which appears to involve endothelial protection from granulocyte-derived noxious compounds and a long-lasting stimulation of PGI2 production.

Animals↗
PubMed1988

The thromboxane receptor antagonist, daltroban, protects the myocardium from ischaemic injury resulting in suppression of leukocytosis.

The cardioprotective action of the new selective inhibitor of thromboxane receptors, daltroban (BM 13.505), was studied in cats subjected to 3 h of coronary artery ligation followed by 2 h of reperfusion. In comparison with vehicle (physiological saline)-treated cats, daltroban (20 mg/kg per h i.v.) reduced the ischaemia-induced rise in the ST segment and prevented the development of a Q-wave in the ECG during reperfusion. This was paralleled by a significantly improved preservation of creatine-phosphokinase activity in the ischaemic myocardium. Daltroban significantly attenuated platelet ATP secretion, the U-46.619-induced contraction of the cat thoracic aorta ex vivo and the myeloperoxidase-associated generation of reactive oxygen species ex vivo. These effects could be largely attributed to the inhibition of ischaemia-induced leukocytosis. It is concluded that daltroban protects the myocardium from ischaemic injury and that this effect involves prevention of ischaemia-induced leukocytosis.

Adenosine Triphosphate↗
PubMed1988

Protection of the ischemic myocardium from reperfusion injury by prostaglandin E1 inhibition of ischemia-induced neutrophil activation.

This study investigates the action of intravenous PGE1 on myocardial reperfusion injury and the possible involvement of antineutrophil activities. Cats were subjected to 3 h of temporary ligation of the left anterior descending coronary artery, followed by 2 h of reperfusion. Animals were treated with PGE1 (5 micrograms/kg x min) or vehicle (saline solution), starting 0.5 h after coronary artery occlusion. Vehicle-treated cats exhibited a significant loss of cardiac creatine phosphokinase specific activity at 5 h, accompanied by a significant ischemia-induced rise in the ST segment of the ECG and development of a Q wave after starting reperfusion. All of these alterations were largely prevented by PGE1 treatment. PGE1 exerted some blood-pressure-lowering activity at 5 h (P greater than 0.05) but did not reduce myocardial contractile force and oxygen consumption. PGE1 modestly antagonized ischemia-induced formation of platelet aggregates. However, PGE1 prevented the rise in peripheral white blood cell count during ischemia and reperfusion and inhibited the generation of reactive oxygen species (myeloperoxidase assay) from zymosan-stimulated whole blood ex vivo. The ratio of generation of reactive oxygen species/white blood count remained unchanged. It is concluded that PGE1 protects the ischemic myocardium from acute reperfusion injury and that this effect involves an action of the compound on neutrophils, probably by improved myocardial tissue preservation, resulting in reduced formation of chemotactic products and, consequently, less local neutrophil accumulation and release of noxious metabolites.

Alprostadil↗
PubMed1988

Potent inhibition of leukotriene (LT) B4 release from human polymorphonuclear leukocytes (PMN) by the PGE1-analogue OP-1206.

The present study investigates the inhibitory action of the PGE1-analogue OP-1206 on stimulated LTB4 release from human PMN. In comparison with PGE2, PGE1 and iloprost, OP-1206 was equipotent to PGE2 and PGE1 as inhibitor of PAF (3 microM) and FMLP (10 microM) induced LTB4 release even in the presence of exogenous arachidonic acid (10 microM). Iloprost was ineffective in this assay at a concentration of 10 microM. The data together with earlier observations suggest that E-type prostaglandins are potent inhibitors of receptor-mediated PMN activation and that these compounds may be valuable for prevention of PMN-associated tissue damage.

Alprostadil↗
PubMed1988

Protection of the ischaemic myocardium from reperfusion injury by defibrotide and its possible mechanism of action.

The following study was designed to investigate the therapeutic value of defibrotide (32 mg/kg bolus + 32 mg/kg x h i.v.) in a cat model of acute myocardial ischaemia (MI) and reperfusion and to elucidate its possible mechanism(s) of action. Infusion of defibrotide (DEF), starting 30 min after the onset of ischaemia, had no effect on any of the hemodynamic parameters measured. In comparison with vehicle-treated animals, DEF largely attenuated the MI-associated ST-segment elevation and completely prevented the development of a pathological Pardee-Q-wave upon reperfusion. Furthermore, DEF largely antagonized the loss of creatine phosphokinase from the ischaemic reperfused myocardium. DEF significantly reduced the MI-induced thrombocytopenia and inhibited the collagen-induced platelet ATP-secretion ex vivo. Interestingly, DEF-treatment did not modify the MI-induced leucocytosis or the release of reactive oxygen radicals from activated neutrophils. These findings indicate that stimulation of endogenous prostacyclin formation by DEF reduces myocardial reperfusion injury independently of any direct effects of the compound on neutrophil activation.

Animals↗
PubMed1987

Biosynthesis of 1-alkenes in higher plants. A model study with the composite Carthamus tinctorius L.

Uneven numbered 1-alkenes, such as 1-pentadecene, 1-heptadecene, 1,8-heptadecadiene, 1,8,11-heptadecatriene and 1,8,11,14-heptadecatetraene are the predominant hydrocarbons in germinating safflower (Carthamus tinctorius L.). According to their chain length and positions of double bonds they are derived from palmitic, stearic, oleic, linoleic or linolenic acid, respectively. This has been proved by administration of synthetic alpha-, beta-, or gamma-deuterated 12-phenyldodecanoic acids to germinating safflower. Mass spectrometric analysis of the resulting deuterium-labelled 11-phenyl-1-undecenes shows that only a single hydrogen from C-3 and carbon dioxide from C-1 of the precursor fatty acid is lost during vinyl group formation. A strong isotope effect (kH/kD greater than or equal to 10) during the conversion of racemic 12-phenyl[3-2h]dodecanoic acid to 11-phenyl-1-[2-2H]undecene is consistent with an initial enzymatic attack on a non-activated hydrogen at C-3 accompanied by simultaneous fragmentation into the respective 1-alkene and carbon dioxide. Mechanisms, based on ionic or radical abstraction of a hydrogen from C-3 of the fatty acid, followed by decarboxylation are discussed. The results are applicable to the formation of various vinylic substituents in natural products such as porphyrins, acetylenic hydrocarbons, pheromones from marine brown algae and terpenoids.

Alkenes↗