Alexander Crea

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1. Leukotriene (LT) B3 was prepared by total chemical synthesis and its identity was confirmed by nuclear magnetic resonance analysis and proton homonuclear plot of connectivities and chemical shift assignments. The effects of LTB3 on complement receptor enhancement, chemotaxis and lysozyme release in human neutrophils (PMN) were compared with those of LTB4(More)
Bronchoalveolar lavage (BAL) was performed on 11 atopic patients with mild asymptomatic bronchial asthma and 11 healthy nonasthmatic volunteers. All asthmatic subjects had evidence of bronchial hyperresponsiveness to inhaled carbachol. The concentrations of leukotriene (LT) C4, LTD4, LTE4, LTB4, prostaglandin D2 (PGD2), platelet-activating factor (PAF) and(More)
The subcellular localization of enzymes involved in leukotriene formation was analysed according to biological (chemotaxis, spasmogenic properties) and analytical methods. By subcellular fractionation the major activity for 5--lipoxygenase and L-gamma-glutamyltranspeptidase coeluted with the 200,000 g precipitate while glutathione-S-transferase activity was(More)
Incubation of eosinophils (EOS) with alveolar macrophage (AM) supernatants isolated from asthmatic subjects followed by stimulation with the calcium ionophore A23187 resulted in enhancement of the capacity of EOS to elaborate leukotriene C4 (LTC4) (mean enhancement 169 +/- 37%, n = 31). Pretreatment of EOS with AM supernatants derived from normal(More)
Lipoxins (LX) are trihydroxytetraene metabolites derived from arachidonic acid via an interaction between the 5- and 15-lipoxygenases. Preincubation of [3H] myo-inositol labeled PMN with 10-7M and 10-5M LXA4 for 1 minute at 37 degrees C resulted in a concentration dependent inhibition of the generation of [3H] IP3 and [3H] IP in cells subsequently(More)
The metabolism of leukotrienes (B4, C4, D4, and E4) within human plasma was studied and a simple sample preparation is presented. It was demonstrated that leukotriene E4 and leukotriene B4 were stable during incubation at 37 degrees C using the in vitro system. In contrast, leukotriene C4 was metabolized by gamma-glutamyl transpeptidase activities into(More)
Bronchial asthma is characterized by airways inflammation and airways hyperresponsiveness. It is unlikely that the pathophysiology of asthma and bronchial hyperresponsiveness can be explained on the basis of a single cell or a single class of mediators. Nevertheless, the possibility that leukotrienes may contribute to the pathogenesis of the inflammatory,(More)
The generation and release of lipoxygenase factors and leukotrienes from human polymorphonuclear granulocytes is demonstrated during bacterial phagocytosis and interaction with bacterial exotoxins (alpha-toxin, enterotoxin, lipase from Staph. aureus; Streptolysin O; cytotoxin from Pseudomonas aeruginosa). The leukotrienes released during stimulation exert(More)
Lipoxins are trihydroxytetraene metabolites which are derived from arachidonic acid through an interaction between different lipoxygenase pathways. Previous work has shown that lipoxin A4 (LXA4) inhibits the chemotactic responsiveness of neutrophils (PMN) to leukotriene B4. We have now assessed the structural determinants of the lipoxin A4 molecule which(More)
Fish oil is rich in the polyunsaturated N-3 fatty acids, eicosapentaenoic (EPA) and docosahexaenoic acids (DCHA). EPA competes with arachidonic acid (AA) for metabolism by the cyclooxygenase and lipoxygenase pathways. Selective metabolites derived from EPA have reduced biological activities as compared with the AA-derived counterparts. Dietary(More)