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1.
The formation of leukotriene B4 and its ω-oxidised metabolites has been compared in calcium ionophore-stimulated polymorphonuclear leukocytes, in the absence of exogenous substrate, from fourteen psoriatic subjects and thirteen healthy controls. Although there was no significant difference in the levels of leukotriene B4, the psoriatic cells synthesised significantly greater amounts of ω-oxidation products than control cells. This difference was confirmed in an experiment comparing the time course of formation of the ω-oxidation products of leukotriene B4, under similar conditions, in polymorphonuclear leukocytes from four psoriatic subjects and three healthy controls. The kinetic constants for the metabolism of exogenous leukotriene B4 by 20-hydroxylase were determined by a radiochromatographic enzyme assay in polymorphonuclear leukocytes from three patients with psoriasis and three healthy controls. No significant differences were found in the apparent Km and Vmax values. It is concluded that the increased formation of ω-oxidation products in psoriatic cells may be secondary to increased synthesis of leukotriene B4 by these cells, with consequent increased metabolism, rather than to an inherent abnormality of the 20-hydroxylase system. Further work is needed to determine the kinetics of the enzymes involved in leukotriene B4 synthesis in the psoriatic polymorphonuclear leukocyte, and also to assess the contribution of the leukotriene B4 and ω-oxidation products from polymorphonuclear leukocytes infiltrating the skin to the pathogenesis of the psoriatic lesion. 相似文献
2.
P. Sirois S. Roy G. Beraldin P. Valler P. Borgeat 《Prostaglandins & other lipid mediators》1982,24(3)
The activity of natural 5,6-Dihydroxy-eicosatetraenoic acid (5,6-DiHETE; 2 isomers), 5S,15S-DiHETE, 8S,15S-DiHETE, 5S,12S-DiHETE, Δ6-trans-leukotriene B4, 12-epi-Δ6-leukotriene B4, ω-hydroxy-leukotriene B4, ω-carboxy-leukotriene B4, 15S-hydroxy-eicosatetraenoic acid (15S-HETE), 12S-HETE, 5S-HETE and 12S-hydroxy-heptadecatrienoic acid was compared to TLB4 on the guinea-pig lung parenchymal strip and on the release of prostaglandins and thromboxanes by the perfused guinea-pig lungs. The ω-hydroxy-LTB4 appeared more potent than LTB4 both for inducing a contraction and for releasing prostanoids whereas the ω-carboxy-LTB4 was much less active on the parenchyma and did not release prostanoids at the dose used. All other hydroxy acids tested were either very weakly active or inactive in the two systems used with the exception of the 5,6-DiHETEs which showed significant activity. These di-hydroxy acids induced contractions of the lung parenchymal strip which could be blocked by PFL-55712 but were inactive on the guinea-pig ileum. The 5S-HETE, 12S-HETE and 15S-HETE were also tested for possible myotropic activity on selected smooth muscle preparations. Our results provide further informations on the structural requirements for LTB4 (and other hydroxy acids) actions on the guinea-pig lungs. 相似文献
3.
The purpose of this study was to determine the role, if any, of Leukotriene B4 (LTB4) in Platelet Activating Factor (PAF)-induced aggregation of rat polymorphonuclear leucocytes (PMNs). Exposure of rat PMNs to 10−7 M PAF resulted in the release of 4.5 ± 0.7 ng/107 cells of LTB4 measured by radioimmunoassay. However, the maximum aggregation of PMNs achieved by exposure to LTB4 (10−7M) was only 50% of that produced by maximally aggregating concentrations of PAF (10−7M). 5-Lipoxygenase inhibitors, BW755c and Nafazatrom at concentrations that completely abolished LTB4 synthesis inhibited the aggregation induced by PAF only by 40% and 50% respectively. Furthermore, desensitisation experiments revealed that the aggregatory response of PMNs to PAF was only partially refractory to prior treatment with LTB4 whereas the aggregatory response to LTB4 was completely refractory to prior treatment with PAF. These results suggest that PAF-induced aggregation of rat PMNs is in part mediated by LTB4 and in part directly by an as yet unidentified mechanism. 相似文献
4.
The widely conserved preferential accumulation of α-tocopherol (α-TOH) in tissues occurs, in part, from selective postabsorptive catabolism of non-α-TOH forms via the vitamin E-ω-oxidation pathway. We previously showed that global disruption of CYP4F14, the major but not the only mouse TOH-ω-hydroxylase, resulted in hyper-accumulation of γ-TOH in mice fed a soybean oil diet. In the current study, supplementation of Cyp4f14−/− mice with high levels of δ- and γ-TOH exacerbated tissue enrichment of these forms of vitamin E. However, at high dietary levels of TOH, mechanisms other than ω-hydroxylation dominate in resisting diet-induced accumulation of non-α-TOH. These include TOH metabolism via ω-1/ω-2 oxidation and fecal elimination of unmetabolized TOH. The ω-1 and ω-2 fecal metabolites of γ- and α-TOH were observed in human fecal material. Mice lacking all liver microsomal CYP activity due to disruption of cytochrome P450 reductase revealed the presence of extra-hepatic ω-, ω-1, and ω-2 TOH hydroxylase activities. TOH-ω-hydroxylase activity was exhibited by microsomes from mouse and human small intestine; murine activity was entirely due to CYP4F14. These findings shed new light on the role of TOH-ω-hydroxylase activity and other mechanisms in resisting diet-induced accumulation of tissue TOH and further characterize vitamin E metabolism in mice and humans. 相似文献
5.
B.S. Tsai R.H. Keith D. Villani-Price R.A. Haack R.F. Bauer R. Leonard Y. Abe K.C. Nicolaou 《Prostaglandins & other lipid mediators》1989,37(2)
A leukotriene B4 (LTB4) analog, 20-trifluoromethyl LTB4 (20CF3−LTB4), has been synthesized and evaluated with human neutrophils for effects on chemotaxis and degranulation. 20CF3−LTB4 was equipotent to LTB4 as a chemoattractant (EC50, 3 nM), produced 50% of maximal activity of LTB4, and competed with [H] LTB4 for binding to intact human neutrophil LTB4 receptors. In contrast to chemotactic activity, 20CF3−LTB4 in nanomolar concentrations exhibited antagonist activity without agonist activity up to 10 μM on LTB4-induced degranulation. The analog had no significant effect on degranulation induced by the chemoattractant peptide, N-formyl-methionyl-leucyl-phenylalanine (fMLP). Like LTB4, 20CF3−LTB4 induced neutrophil desensitization to degranulation by LTB4. The results indicate that hydrogen atoms at C-20 of LTB4 are critical for its intrinsic chemotactic and degranulation activities. The fact that 20CF3−LTB4 is a partial agonist for chemotaxis and an antagonist for degranulation syggests that different LTB4 receptor subtypes are coupled to these neutrophil functions. Desensitization of the neutrophil degranulation response to LTB4 can result from receptor occupancy by an antagonist, and therefore, the desensitization is not specific for an agonist. 相似文献
6.
Alice H. Lin Patricia L. Ruppel Robert R. Gorman 《Prostaglandins & other lipid mediators》1984,28(6):837-849
[3H] Leukotriene B4 (LTB4) binds concentration dependency to intact human polymorophonuclear leukocytes (PMN's). The binding is saturable, reaches equilibrium in 10 min at 4°C, and is readily reversible. Mathematical modeling analysis reveals biphasic binding of [3H] LTB4 indicating two discrete populations of binding sites. The high affinity binding sites have a dissociation constant of 0.46 × 10−9M and Bmax of 1.96 × 104 sites per neutrophil; the low affinity binding sites have a dissociation constant of 541 × 10−9M and a Bmax of 45.6 × 104 sites per neutrophil. Competitive binding experiments with structural analogues of LTB4 demonstrate that the interaction between LTB4 and the binding site is stereospecific, and correlates with the relative biological activity of the analogs. At 25°C[3H] LTB4 is rapidly dissociated from the binding site and metabolized to 20-OH and 20-COOH-LTB4. Purification of neutrophils in the presence of 5-lipoxygenase inhibitors significantly increases specific [3H] LTB4 binding, suggesting that LTB4 is biosynthesized during the purification procedure. These data suggest that stereospecific binding and metabolism of LTB4 in neutrophils are tightly coupled processes. 相似文献
7.
Pankaj K Bhavsar Bruce D Levy Mark J Hew Michael A Pfeffer Shamsah Kazani Elliot Israel Kian Fan Chung 《Respiratory research》2010,11(1):71
Background
An imbalance in the generation of pro-inflammatory leukotrienes, and counter-regulatory lipoxins is present in severe asthma. We measured leukotriene B4 (LTB4), and lipoxin A4 (LXA4) production by alveolar macrophages (AMs) and studied the impact of corticosteroids.Methods
AMs obtained by fiberoptic bronchoscopy from 14 non-asthmatics, 12 non-severe and 11 severe asthmatics were stimulated with lipopolysaccharide (LPS,10 μg/ml) with or without dexamethasone (10-6M). LTB4 and LXA4 were measured by enzyme immunoassay.Results
LXA4 biosynthesis was decreased from severe asthma AMs compared to non-severe (p < 0.05) and normal subjects (p < 0.001). LXA4 induced by LPS was highest in normal subjects and lowest in severe asthmatics (p < 0.01). Basal levels of LTB4 were decreased in severe asthmatics compared to normal subjects (p < 0.05), but not to non-severe asthma. LPS-induced LTB4 was increased in severe asthma compared to non-severe asthma (p < 0.05). Dexamethasone inhibited LPS-induced LTB4 and LXA4, with lesser suppression of LTB4 in severe asthma patients (p < 0.05). There was a significant correlation between LPS-induced LXA4 and FEV1 (% predicted) (rs = 0.60; p < 0.01).Conclusions
Decreased LXA4 and increased LTB4 generation plus impaired corticosteroid sensitivity of LPS-induced LTB4 but not of LXA4 support a role for AMs in establishing a pro-inflammatory balance in severe asthma. 相似文献8.
Tafalla C Medina I Figueras A Novoa B 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》1999,123(4):945-356
Production of two eicosanoids derived from lipoxygenase and cyclooxygenase activities: leukotriene B4 (LTB4) and prostaglandin E2 (PGE2), respectively, have been simultaneously determined in turbot (Scophthalmus maximus) blood leucocyte and kidney macrophage supernatants by a reverse phase high performance liquid chromatography (HPLC) system coupled with a Diode–Array detector. Levels of LTB4 after calcium ionophore challenge were 4.08 ng ml−1 in blood leukocyte supernatants and 0.25 ng ml−1 in kidney macrophage supernatants. The levels found for PGE2 were 428.23 and 606.67 ng ml−1 in blood leukocytes and kidney macrophage supernatants, respectively. When blood leukocytes were treated with the respective inhibitors for the enzymes implicated on the synthesis of both compounds an inhibition of 90.35% was observed for PGE2 and 76.44% for LTB4. The detection limit of the method was 0.15 ng ml−1 for LTB4 and 50 ng ml−1 for PGE2. 相似文献
9.
A.W. Ford-Hutchinson G. Brunet P. Savard S. Charleson 《Prostaglandins & other lipid mediators》1984,28(1):13-27
Leukocyte numbers and Leukotriene B4- (LTB4-) and LTC4-immunoreactivity were measured in inflammatory exudates obtained from sponges impregnated with several irritants implanted subcutaneously in the rat. Sponges containig 1% uric acid, carragennan or zymosan were implanted for 5h and compared to saline sponges. Increases in leukocyte numbers and LTB4-immunoreactivity were found in the presence of irritants, the highest concentrations being observed in the presence of zymosan. The presence of LTB4 was confirmed by liquid chromatographic (HPLC) analysis. A time course study was carried out with zymosan-impregnated sponges and the maximal rate of leukocyte infiltrations was found to coincide with the maximal levels of LTB4-immunoreactivity. The LTC4-immunoreactivity was low and following analysis by HPLC was concluded to be unrelated to leukotrienes. The levels of LTB4-immunoreactivity, but not the numbers of leukocytes, were elevated compared to corresponding controls in sponges containing 0.01% ionphore A23187 (untreated rats) or in sponges containing zymosan (rats pretreated with indomethacin; 3 and 10 mg/kg p.o.). Impregnation of sponges with 3 × 10−6M LTB4 but not 3 × 10−7M LTB4 induced a significant leukocyte migration. It was concluded that LTB4 can induced leukocyte migration into sponge exudates in the rat but that measurements of LTB4 in such exudates can not be correlated with the degree of leukocyte infiltration. 相似文献
10.
William F. Stenson Kathy Chang Joseph R. Williamson 《Prostaglandins & other lipid mediators》1986,32(1)
The activity of synthetic LTB4 and PGE2, in increasing vascular permeability was tested simultaneously in seventeen different organs in the rat. Rats were injected in the aortic arch through a cannula in the carotid artery with 125-I-albumin, 51Cr-erythrocytes, and 57Co-EDTA. The rats were then injected through the carotid artery cannula with LTB4, PGE2 or a combination of LTB4 and PGE2. Eight minutes later the rats were killed and the activity of 125I, 51Cr, and 57Co measured in different organs. Changes in vascular permeability were infered from changes in the ratios of the isotope activities. LTB4 (15 μg/kg) induced enhanced permeability in caecum, small bowel, skin, fat pad, stomach, pancreas, and aorta, but not in the heart, brain, colon, testes, diaphragm, forelimb, cremaster muscle, lung, kidney or eye. A lower dose of LTB4, 3 μg/kg, enhanced vascular permeability in caecum, small bowel, skin, stomach, and aorta. PGE2 (1 μg/kg) enhanced vascular permeability only in the caecum. A combination of LTB4 (3 μg/kg) and PGE2 (1 μg/kg) was more potent than either alone. Rats depleted of neutrophils with anti-neutrophil serum were less sensitive to LTB4 than intact rats. These findings suggest that the vasculatures of different tissues in the rat vary markedly in their susceptibility to LTB4 induced increases in permeability. 相似文献
11.
Stephen M. Prescott Guy A. Zimmerman Aubrey R. Morrison 《Prostaglandins & other lipid mediators》1985,30(2):209-227
Diets that are enriched with fish oil have been shown to alter arachidonic acid metabolism via the cyclooxygenase pathway. Recently it has been shown that one of the major component fatty acids of fish oil, eicosapentaenoate (EPA), is a substrate for the leukotriene B (LTB) pathway when added exogenously to human neutrophils
. We fed a diet that contained 8–10 gm/day of EPA to four human subjects for three weeks and compared the arachidonate metabolism of their neutrophils to the same functions while the subjects were on their usual diet. The fish oil-supplementation increased neutrophil EPA content from undetectable levels to 7.4 ± 2.4% (p<0.01, expressed as % of total fatty acid), and decreased arachidonate from 15.4 ± 2.3% to 12.8 ± 2.3% (p<0.05). Leukotriene B5 was identified as a metabolite during the fish oil-diet by its chromatographic profile and mass spectrum. During the experimental diet LTB4 decreased from 160 ± 37 ng/107 neutrophils to 120 ± 12 (p<0.05), and LTB5 increased from 0 to 39 ± 9 ng/107 neutrophils (p<0.005). The diet had no effect on neutrophil aggregation or adherence to nylon fibers. 相似文献
12.
Leukotrienes (LTs), chemical mediators produced by mast cells, play an important role in allergic symptoms such as food allergies and hay fever. We tried to construct an evaluation method for the anti-LTB4 activity of chemical substances using a mast cell line, PB-3c. PB-3c pre-cultured with or without arachidonic acid (AA) was stimulated by calcium ionophore (A23187) for 20 min, and LTB4 production by the cells was determined by HPLC with UV detection. LTB4 was not detected when PB-3c was pre-cultured without AA. On the other hand, LTB4 production by PB-3c pre-cultured with AA was detectable by HPLC, and the optimal conditions of PB-3c for LTB4 detection were to utilize the cells pre-cultured with 50 µM AA for 48 h. MK-886 (5-lipoxygenase inhibitor) completely inhibited LTB4 production, but AACOCF3 (phospholipase A2 inhibitor) slightly increased LTB4 production, suggesting that LTB4 was generated from exogenous free AA through 5-lipoxygenase pathway. We applied this technique to the evaluation of the anti-LTB4 activity of food components. PB-3c pre-cultured with 50 µM AA for 48 h was stimulated with A23187 in the presence of 50 µM soybean isoflavones (daidzin, genistin, daidzein, and genistein), equol, quercetin, or kaempferol. Genistein, equol, quercetin, and kaempferol strongly inhibited LTB4 production without cytotoxicity. These results suggest that a new assay system using PB-3c is convenient to evaluate LTB4 inhibition activity by food components. This method could be utilized for elucidation of the mechanisms of LTB4 release suppression by food components such as flavonoids and the structure–activity relationship. 相似文献
13.
Paolo Montuschi Simona Martello Marialinda Felli Chiara Mondino Peter J Barnes Marcello Chiarotti 《Respiratory research》2005,6(1):119
Background
The role of leukotriene (LT) B4, a potent inflammatory mediator, in atopic asthmatic and atopic nonasthmatic children is largely unknown. The lack of a gold standard technique for measuring LTB4 in exhaled breath condensate (EBC) has hampered its quantitative assessment in this biological fluid. We sought to measure LTB4 in EBC in atopic asthmatic children and atopic nonasthmatic children. Exhaled nitric oxide (NO) was measured as an independent marker of airway inflammation.Methods
Fifteen healthy children, 20 atopic nonasthmatic children, 25 steroid-naïve atopic asthmatic children, and 22 atopic asthmatic children receiving inhaled corticosteroids were studied. The study design was of cross-sectional type. Exhaled LTB4 concentrations were measured using liquid chromatography/mass spectrometry-mass spectrometry (LC/MS/MS) with a triple quadrupole mass spectrometer. Exhaled NO was measured by chemiluminescence with a single breath on-line method. LTB4 values were expressed as the total amount (in pg) of eicosanoid expired in the 15-minute breath test. Kruskal-Wallis test was used to compare groups.Results
Compared with healthy children [87.5 (82.5–102.5) pg, median and interquartile range], exhaled LTB4 was increased in steroid-naïve atopic asthmatic [255.1 (175.0–314.7) pg, p < 0.001], but not in atopic nonasthmatic children [96.5 (87.3–102.5) pg, p = 0.59)]. Asthmatic children who were receiving inhaled corticosteroids had lower concentrations of exhaled LTB4 than steroid-naïve asthmatics [125.0 (25.0–245.0) pg vs 255.1 (175.0–314.7) pg, p < 0.01, respectively]. Exhaled NO was higher in atopic nonasthmatic children [16.2 (13.5–22.4) ppb, p < 0.05] and, to a greater extent, in atopic steroid-naïve asthmatic children [37.0 (31.7–57.6) ppb, p < 0.001] than in healthy children [8.3 (6.1–9.9) ppb]. Compared with steroid-naïve asthmatic children, exhaled NO levels were reduced in asthmatic children who were receiving inhaled corticosteroids [15.9 (11.5–31.7) ppb, p < 0.01].Conclusion
In contrast to exhaled NO concentrations, exhaled LTB4 values are selectively elevated in steroid-naïve atopic asthmatic children, but not in atopic nonasthmatic children. Although placebo control studies are warranted, inhaled corticosteroids seem to reduce exhaled LTB4 in asthmatic children. LC/MS/MS analysis of exhaled LTB4 might provide a non-invasive, sensitive, and quantitative method for airway inflammation assessment in asthmatic children. 相似文献14.
P. Perrin J. Zirrolli D.O. Stene J.P. Lellouche J.P. Beaucourt R.C. Murphy 《Prostaglandins & other lipid mediators》1989,37(1)
Intraperitoneal administration of [3H]-leukotriene E4 in the rat resulted in the appearance of radiolabel in urine and feces. Separation of polar urinary metabolites and chromatographic comparison of synthetic metabolites indicated the in vivo formation of ω-oxidized metabolites of LTE4 with sequential β-oxidation. Futhermore, the metabolite identified as 16-carboxy-17,18,19,20-tetranor-14,15-dihydro-N-acetyl-LTE4 substantiates the biochemical patheway of β-oxidation in vivo involving the 2,4-dienoyl CoA reductase as an integral step. These results substantiate β-oxidation of sulfidopeptide leukotrienes in vivo and these metabolites account for some of the major urinary metabolites of this class of lipid mediator. 相似文献
15.
M. Braquet P. Lavaud D. Dormont R. Garay R. Ducousso J. Guilbaud M. Chignard P. Borgeat P. Braquet 《Prostaglandins & other lipid mediators》1985,29(5):747-764
Anergy associated with an increase in suppressor helper T cell (Tc) ratio and a decrease in natural killer (NK) is one main cause of death following thermal injury (Tl). Recently, in vitro studies have shown that LTB4 can induce human Tc to exert suppressor cell activity, and incubation of lymphocytes with LTB4 for 24 hours significantly suppressed NK cell activity. Thus, we undertook an investigation of both AA metabolism and immunologic response in 20 patients who suffered 40–90% total body surface area (TBSA) burns. Cyclooxygenase (CO:RIA) and lipoxygenase (LO;HPLC det.) metabolites and superoxide (O2.−) production were measured in stimulated polymorphonuclear cells (PMNL) (A 23187 ± AA for icosanoid release; phorbol myristate acetate for O2.− production). Lyso-paf-acether (P-LPA) was measured in plasma samples. Ca2+-dependent K+ permeability in PMNL was measured by the cell K+ release induced by A 23187. Tc and Tc subsets were determined using monoclonal antibodies (OKT3+, OKT4+ and OKT8+). A biphasic sequential release of the different substances (leukocytic icosanoids and O2.− was monitored: increase ( 36–48 h after Tl) and decrease ( 72 h after Tl). The increase in AA stimulation was more transient than that of O2.−. The decline in the release of AA metabolites and O2.− production was associated with the anergic phase (decrease OKT4+/OKT8+ ratio) and with the clinical outcome of the patients. The decrease in LTB4 and other LO metabolites could explain the impairment of neutrophil chemotaxis. Ca2+-dependent K+ permeability increased early up to 2 or 3 times normal.In order to go further with the mechanism of inhibition of LTB4 and O2.− release, the effect of Tl plasma was assayed on normal leukocytes: a 10 min incubation with such plasma was sufficient to abolish LTB4 secretion. A less important inhibition was observed with O2.− release (−32%) and Ca2+-dependent K+ permeability (−30%). Plasma inhibition seems to be due to a thermolabile factor(s) [protein(s): “suppressive factor(s) of membrane activation ”SFMA] which is (are) under active investigation using gel-filtration chromatography and fast protein liquid chromotography (FPLC). Among the SFMAs, certain acute phase proteins could play a key role: i.e., incubation (10 min) of normal PMNL with ceruloplasmin (1 mg/ml) abolished LO products and O2.− release. 相似文献
16.
P. Tagari A. Foster D. Delorme Y. Girard J. Rokach 《Prostaglandins & other lipid mediators》1989,37(6)
Four novel ω- and β-oxidation (from the ω end) products of peptide leukotrienes, 20-hydroxy and 20-carboxy-LTE4, 18-carboxy-19,20-dinor-LTE4 and 16-carboxy-17, 18, 19, 20-tetranor-14, 15-dihydro-LTE4 were prepared by total synthesis and used as standards for identification of biliary and urinary metabolites in the cynomolgus monkey. After intravenous administration 14, 15,-[3H] leukotriene C4 (10 μCi kg−1 was partially metabolized in and rapidly cleared from the vascular circulation. This resulted, within 24 hours, in significant urinary excretion. (14.8 ± 2.1%, n = 4), consisting largely of material more polar than LET4 (61% of urinary excretion) as shown by reverse phase HPLC. The polar fraction demonstrated two predominant metabolites which coeluted in several HPLC solvent systems with synthetic 16-carboxytetranordihydro-LTE4 (major component) and 18-carboxydinor-LTE4 (minor component). Characterization of the major polar metabolites as 16-carboxytetranordihydro-LTE4 was substantiated by conversion to its N-acetylated derivative. The absence of the 14, 15 double bond was confirmed by product analysis of oxidative ozonolysis. In a single animal, the bile duct was cannulated, with significant biliary excretion of radioactivity demonstrated over 4 hours (58.6% recovery). The predominant polar biliary metabolites were also identified as the 18-carboxydinor and 16-carboxytetranordihydro derivatives of LTE4 mentioned above. These data suggest that β-oxidation products generated from the ω-carboxyl end of the 20-carboxyl-LTE4 are important products of [3H] LTC4 metabolism in the monkey. Quantitation of these urinary metabolites may be an important index of
leukotriene production. 相似文献
17.
S.T. Hoffstein R.M. Manzi K.A. Razgaitis P.E. Bender J. Gleason 《Prostaglandins & other lipid mediators》1986,31(2)
LTB4 (5s, 12R dihdroxy-6, 14-CIS-8, 10-trans-eicosatetraenoic acid) formed in activated neutrophils by lipoxygenation of arachidonic acid is an extremely potent chemotaxin. We examined structural requirements for chemotactic and aggregatory activity of the ligand using synthetic LTB4 and several of its isomers. Additionally we examined the potency of two analogs, nor- and homo- LTB4. Dose response curves for neutrophil chemotaxis to these compounds were obtained using a modified Boyden chamber. The mean distance cells moved into the filter was determined after 30 minutes. Peak chemotactic activity of LTB4 was at 10−7M. At higher concentrations, chemotactic activity was decreased. The shape of the dose response curve was similar to that of FMLP except that maximum chemotaxis to LTB4 was consistently greater than chemotaxis to FMLP. A mixture of the two epimers at C-5 and c-12 shifted the response curve to the right but did not lower maximum activity. Increasing or decreasing the chain by one carbon between the first hydroxyl group and the carboxyl group also shifted the response curve to the right without lowering maximal activity. Changing the 6 double bond from cis to trans has a greater effect. Activity was only detectable at high concentrations and maximum activity achieved was less than 50% that of LTB4. Thus the chain length between the carboxyl and C-5 hydroxyl groups, the c-5 and c-12 absolute stereochemistry and the stereochemistry of the delta6 double bond are all important structural features for chemotactic activity with delta6 stereochemistry apparently having the greatest contribution. The relative potencies of these compounds in inducing aggregation were comparable to their chemotactic potencies. The data suggested that they acted at the same receptor since even the less active isomers were able to desensitive the neutrophils to LTB4. 相似文献
18.
Two novel β-oxidation products of peptido leukotrienes, 16-carboxy-17, 18, 19, 20-tetranor-14, 15-dihydro-N-acetyl LTE4 and 18-carboxy-19, 20-dinor-N-acetyl LTE4, were prepared by total synthesis and used to identify previously unknown polar rat biliary metabolites. When [3H] LTC4 and synthetic N-acetyl-LTE4 were administered intravenously to anesthetized inbred male rats, extraction of the bile and subsequent reverse-phase HPLC fractionation allowed the isolation of two novel metabolites of N-acetyl-LTE4. Comparison of U.V. spectra and coelution experiments revealed that these metabolites correspond to the above-mentioned synthetic β-oxidation products. This was further confirmed by the coelution of the corresponding methyl esters. Oxidative ozonolysis of the metabolically produced 16-carboxy-17, 18, 19, 20-tetranor-14, 15-dihydro-N-acetyl LTE4 (major metabolite) confirmed the absence of the 14, 15-unsaturation. The presence of these metabolites indicates that peptide leukotrienes undergo N-acetylation followed by ω and subsequent β-oxidation in the anesthetized rat. 相似文献
19.
We have evaluated the biosynthesis, characterization and inhibition of Leukotrien (LT) B4 in unstimulated and in A23187-stimulated human whole blood. LTB4 was assayed by radioimmunoassay (RIA) both in unextracted serum and after extraction and thin-layer chromatography (TLC). Unstimulated human whole blood allowed to clot at 37°C for 60 min produced only trace amounts of LTB4 (0.16±0.05 ng/ml, mean±SD, n=3). LTB4-like immunoreactivity (ir-LTB4) detectable in unstimulated serum samples was largely overestimated by direct RIA, most likely because of interfering substance(s) unrealed to cyclooxygenasep or lipoxygenase activity. Incubation of human whole blood with A23187 (2–10 μM) resulted in a concentration-dependent stimulation of LTB4 production. At 10 μM A23187, ir-LTB4 was 18±2.4 ng/ml (mean±SEM, n=28). In A23187-stimulated serum samples, LTB4 concentrations measured by direct RIA correlated in a statistically significant fashion with those measured after extraction and TLC. Nafazatrom added
caused a dose-dependent inhibition of A23187-stimulated ir-LTB4 production with an IC50 of 17 μM. 相似文献
20.
William E. Serafin John A. Oates Walter C. Hubbard 《Prostaglandins & other lipid mediators》1984,27(6):899-911
Five milligrams of [5,6,8,9,11,12,14,15-3H8]-leukotriene B4 (LTB4) (1.68 Ci/mmol) were infused into a monkey over a three hour period. Twenty-five per cent of the infused 3H-activity was recovered in the urine during the twenty hours of collection. Plasma and urinary metabolite volatility studies revealed that in contrast to previously studied eicosanoids, more than 70% per cent of the infused LTB43H-label was converted to tritiated water. The major nonvolatile urinary metabolite of LTB4 representing 0.8% of the infused material was identified as 20-OH-LTB4. LTB4 was not excreted in the urine. Other nonvolatile metabolites of LTB4 representing less than 0.4% each of the infused material were isolated from the urine. While there was an adequate quantity of some of these metabolites for partial characterization, there was insufficient material for structural elucidation. Further studies were performed in rabbits in which either LTB4 or the structurally related compound 8,15-dihydroxyeicosatetraenoic acid (8,15-diHETE) were infused intravenously. In these rabbits the metabolism of LTB4 and 8,15-diHETE was similar to that in the monkey with greater than 80% of the infused 3H-activity converted to tritiated water. These studies suggest that leukotriene B4 and structurally related compounds undergo extensive degradation in vivo via the β-oxidation system. 相似文献