Showing papers in "Prostaglandins Leukotrienes and Essential Fatty Acids in 1998"
TL;DR: In this investigation, effects of naturally occurring flavonoids on epidermal cyclooxygenase/lip oxygengenase were studied using five selected derivatives: flavanone, apigenin, quercetin (flavonol), amentoflavone and ginkgetin (biflavone) because eicosanoids generated in the epidermis are believed to be involved in various biological activities of the skin.
Abstract: Although there have been numerous topical applications of plant extracts having flavonoids known as anti-inflammatory compounds, only a few studies were reported concerning effects of flavonoids on epidermal cyclooxygenase/lipoxygenase. In this investigation, effects of naturally occurring flavonoids on epidermal cyclooxygenase/lipoxygenase were studied using five selected derivatives: flavanone, apigenin (flavone), quercetin (flavonol), amentoflavone and ginkgetin (biflavone) because eicosanoids generated in the epidermis are believed to be involved in various biological activities of the skin. Microsomal and cytosolic fractions were obtained from guinea-pig epidermal homogenate by centrifugation and used as a source for cyclooxygenase and lipoxygenase. It was found that quercetin inhibited both cyclooxygenase and lipoxygenase, being more potent against lipoxygenase, while flavanone and apigenin did not show any inhibition. Amentoflavone, one of the biflavones tested, showed potent and selective inhibitory activity on cyclooxygenase (IC50 = 3 microM) which was comparable to indomethacin (IC50 = 1 microM). In contrast, structurally similar ginkgetin possessed weak inhibitory activity on cyclooxygenase. The in vivo effects of these flavonoids on the normal and diseased skin remain to be studied.
282 citations
TL;DR: This 8-iso PGF2alpha radioimmunoassay method is relevant to apply in the oxidative injury studies as an index of in vivo lipid peroxidation through free radical catalysis mechanism and found to correlate with the obtained values by gas chromatography-mass spectrometry methods from other studies.
Abstract: Radioimmunoassay of 8-isoprostaglandin F2alpha: an index for oxidataive injury via free radical catalysed lipid peroxidation
262 citations
TL;DR: Two important paraffinic polysulphides derived from garlic and are usual constituents of garlic oil, showed antiplatelet activity, and also inhibited platelet thromboxane formation, and DATS was more potent than DADS.
Abstract: Thirty patients with coronary artery disease (CAD) were administered garlic (study group) while another 30 patients received the placebo (control group). Various risk parameters were determined at 1.5 and 3 months of garlic administration. Garlic, administered in a daily dose of 2 x 2 capsules (each capsule containing ethyl acetate extract from 1 g peeled and crushed raw garlic), reduced significantly total serum cholesterol and triglycerides, and increased significantly HDL-cholesterol and fibrinolytic activity. There was no effect on the fibrinogen and glucose levels. In vitro effects of the garlic oil on platelet aggregation (PAg) and eicosanoid metabolism were examined; it inhibited PAg induced by several platelet agonists, and also platelet thromboxane formation. Two important paraffinic polysulphides - diallyl disulphide (DADS) and diallyl trisulphide (DATS) - derived from garlic and are usual constituents of garlic oil, showed antiplatelet activity, and also inhibited platelet thromboxane formation. In this respect DATS was more potent than DADS. The nature of inhibition of PAg by DATS was found to be reversible.
224 citations
TL;DR: The development and validation of a new radioimmunoassay of 15-keto-dihydro-PGF2alpha as an index of lipid peroxidation via cyclooxygenase (COX-1 and COX-2) pathway is presented and its application in endotoxin-induced acute inflammation in pigs is presented.
Abstract: Radioimmunoassay of 15-keto-13,14-dihydro-prostaglandin F2alpha: an index for inflammation via cyclooxygenase catalysed lipid peroxidation
143 citations
TL;DR: It is demonstrated that H. pylori infection leads to gastric mucosal expression of COX-2, indicating that the enzyme is involved in H.pylori-related gastric pathology in humans.
Abstract: Recent studies indicate that expression of mitogen-inducible cyclooxygenase-2 (COX-2) occurs in gastrointestinal tumors. We investigated the effects of Helicobacter pylori (H. pylori) infection, a class I carcinogen for the human stomach, on gastric COX-2 expression using immunohistochemistry. Human subjects without macroscopic lesions, as determined by endoscopic screening, were biopsied for H. pylori infection. The biopsy samples were immunohistochemically examined for COX-2 expression. COX-2 was expressed in gastric epithelia and subepithelial inflammatory cells in all H. pylori-infected subjects. There was no expression of COX-2 in the gastric mucosa of H. pylori-negative subjects. COX-2 expression has been reported in gastrointestinal carcinomas, gastrointestinal cancer cell-lines, and in the gut after carcinogenic treatment. The present study demonstrates that H. pylori infection leads to gastric mucosal expression of COX-2, indicating that the enzyme is involved in H. pylori-related gastric pathology in humans.
97 citations
TL;DR: Data suggest that irrespective of the availability of a specific fatty acid as a substrate, through regulating the PGE 2 synthesis, the production of TNF-α could be modulated.
Abstract: Sesamin (a non-fat portion of sesame seed oil) inhibits delta-5 desaturase activity resulting in an accumulation of dihomo-gamma-linolenic acid (DGLA) which can displace arachidonic acid (AA) and decrease the formation of pro-inflammatory mediators. We investigated the effects of consumption of diets containing 0.25wt% sesamin and 15 wt% safflower oil (SO) (providing 12% of the added fat as linoleic acid) or a 15 wt% 2:1 mixture of linseed oil and SO (LOSO) (providing 6% alpha-linolenic acid and 6% linoleic acid) for 3 weeks on the liver membrane fatty acid composition and on the production of prostaglandin (PG) E2, TNF-alpha, IL-6 and IL10 in mice. Consumption of sesamin-supplemented SO and LOSO diets resulted in a significant increase in the levels of 20:3omega6 (DGLA), suggesting that sesamin inhibited delta-5 desaturation of omega6 fatty acids. In animals fed LOSO diets, the levels of alpha-linolenic acid, eicosapentaenoic acid (EPA) and of docosahexaenoic acid (DHA) were elevated with a concomitant decrease of arachidonic acid (AA) in the liver membrane phospholipids. Further, in animals fed LOSO diets with or without sesamin, an increase in the circulating levels of TNF-alpha was associated with a concomitant decrease in PGE2. Despite a lack of differences in the levels of AA, the PGE2 levels were significantly lower in mice fed sesamin-supplemented SO compared to those fed SO alone. Thus, these data suggest that irrespective of the availability of a specific fatty acid as a substrate, through regulating the PGE2 synthesis, the production of TNF-alpha could be modulated.
79 citations
TL;DR: The high-LA diet increased oxidative stress and affected endothelial function in a way which may in the long-term predispose to endothelial dysfunction.
Abstract: Evidence from in vitro studies shows that increased intake of polyunsaturated fatty acids leads to increased oxidative stress, which may be associated with endothelial damage. We measured the urinary levels of 8-iso-PGF2alpha and nitric oxide metabolites as well as plasma sICAM-1 levels from healthy subjects after strictly controlled diets rich in either linoleic acid (LA, C18:2 n-6) or oleic acid (OA, C18:1 n-9). Thirty-eight volunteers (20 women and 18 men, mean age 27 years) consumed a baseline diet rich in saturated fatty acids (SFA) for 4 weeks and were then switched to either a high LA diet (11.5 en%) or a high OA diet (18.0 en%) also for 4 weeks. During the LA and OA diets, nearly all food was provided for the whole day. A control group of 13 subjects consumed their habitual diet throughout the study. Urinary excretion of 8-iso-PGF2alpha was significantly increased after the LA diet (170 vs 241 ng/mmol creatinine, P=0.04), whereas the urinary concentration of nitric oxide metabolites decreased (4.2 vs 2.6 mg/mmol creatinine, P=0.03). No significant changes were seen in the OA group. Significant differences between the LA and control group were found for both 8-oxo-PGF2alpha (P=0.03) and NO (P=0.02), whereas the OA and LA groups did not differ with respect to any parameter. Also plasma sICAM-1 remained unchanged in both groups throughout the study. In conclusion, the high-LA diet increased oxidative stress and affected endothelial function in a way which may in the long-term predispose to endothelial dysfunction.
76 citations
TL;DR: The results of a 2-week, randomized, double-blind, placebo-controlled trial investigating the effects of policosanol on platelet aggregation and thromboxane B2 and prostacyclin production after stimulation with collagen in healthy volunteers were reported.
Abstract: Policosanol is a cholesterol-lowering drug with hypocholesterolemic effects demonstrated in experimental models, healthy volunteers and patients with type II hypercholesterolemia. In addition, antiplatelet effects of policosanol have been shown in experimental models and healthy volunteers. This study reports the results of a 2-week, randomized, double-blind, placebo-controlled trial investigating the effects of policosanol on platelet aggregation and thromboxane B2 and prostacyclin (6 keto PGF1alpha) production after stimulation with collagen in healthy volunteers. The volunteers were on a placebo-baseline period for 7 days and thereafter they received randomly, under double-blind conditions, placebo or policosanol (10 mg/day) for 15 days. Platelet aggregation was determined at baseline and after 15 days of treatment. Significant reductions of arachidonic acid and collagen-induced platelet aggregation were observed. Thromboxane, but not prostacyclin, generation induced by collagen was also inhibited by policosanol.
76 citations
TL;DR: Levels of various anti-oxidants, p53 expression and the concentrations of protein kinase C suggest that essential fatty acids and their metabolites can reverse tumour cell drug-resistance at least in vitro.
Abstract: Tumour cell drug resistance is a major problem in cancer chemotherapy. Essential fatty acids have been shown to be cytotoxic to a variety of tumour cells in vitro. But, the effect of these fatty acids on tumour cell drug resistance has not been well characterized. Gamma-linolenic acid (GLA) of the n-6 series and eicosapentaenoic acid (EPA) of the n-3 series potentiated the cytotoxicity of anti-cancer drugs: vincristine, cis-platinum and doxorubicin on human cervical carcinoma (HeLa) cells in vitro. Alpha-linolenic acid (ALA), GLA, EPA and docosahexaenoic acid (DHA) enhanced the uptake of vincristine by HeLa cells. In addition, DHA, EPA, GLA and DGLA were found to be cytotoxic to both vincristine-sensitive (KB-3-1) and -resistant (KB-ChR-8-5) human cervical carcinoma cells in vitro. Pre-incubation of vincristine-resistant cells with sub-optimal doses of fatty acids enhanced the cytotoxic action of vincristine. GLA, DGLA, AA, EPA and DHA enhanced the uptake and inhibited the efflux of vincristine and thus, augmented the intracellular concentration of the anti-cancer drug(s). Fatty acid analysis of KB-3-1 and KB-ChR-8-5 cells showed that the latter contained low amounts of ALA, GLA, 22:5 n-3 and DHA in comparison to the vincristine-sensitive cells. The concentrations of GLA and DHA were increased 10-15 fold in the phospholipid, free fatty acid and ether lipid cellular lipid pools of GLA and DHA treated cells. These results coupled with the observation that various fatty acids can alter the activity of cell membrane bound enzymes such as sodium-potassium-ATPase and 5'-nucleotidase, levels of various anti-oxidants, p53 expression and the concentrations of protein kinase C suggest that essential fatty acids and their metabolites can reverse tumour cell drug-resistance at least in vitro.
73 citations
TL;DR: In the vegetarian mothers, the PUFA profiles in the maternal erythrocytes, placenta and cord are consistent with an elevation in the rate ofLCPUFA synthesis in order to make up the relative deficit in LCPUFA intake, however, it may be that the higher level of desaturase activity is not able to overcome the dietary deficit of 22-6 n-3 and 22: 6 n-6.
Abstract: The aim of this study was to determine the effect of fatty acid intake and insulin dependent diabetes on the fatty acid composition of maternal erythrocytes, the placenta and cord. Fatty acid intake (from food frequency questionnaire) and the fatty acid composition of maternal erythrocytes, the placenta and cord from pregnant vegetarians (n = 4) and insulin dependent diabetics (n = 5) was compared with pregnant omnivores (n = 10). There was a significantly lower intake of n-6 long chain polyunsaturated fatty acid (LCPUFA) (-75% P < 0.01) and n-3 LCPUFA (-92% P < 0.01) and increased ratio of n-6/n-3 LCPUFA in the vegetarians (103%; P < 0.001). The concentrations of 22:4 n-6 (+28%; P < 0.05) and 22:5 n-3 (+40%; P < 0.05) were higher in vegetarian erythrocytes. Placental 18:2 n-6 (+26.9%; P < 0.05) 18:3 n-3 (+139%; P < 0.05) and 22:5 n-3 (+24%; P < 0.05) were increased while 20:5 n-3 (-36%; P < 0.05), 22:6 n-3 (-16%; P = 0.059), and the ratios of 20:4 n-6/18:2 n-6 (P < 0.01) and 22:6 n-3/18:3 n-3 were reduced. 22:6 n-6 (-49%; P < 0.05) and total n-3 LCPUFA (-11%; P < 0.01) were reduced in vegetarian cord. For the diabetic mothers, all of the n-6 LCPUFA and n-3 LCPUFA were reduced in the maternal erythrocytes; 22:4 n-6 (-42%; P < 0.05), 22:5 n-6 (-46%; P < 0.05) and 22:6 n-3 (-41%; P < 0.05). For the diabetic placenta and cord the general pattern of n-3 LCPUFA was the same as that in the vegetarians. In the vegetarian mothers, the PUFA profiles in the maternal erythrocytes, placenta and cord are consistent with an elevation in the rate of LCPUFA synthesis in order to make up the relative deficit in LCPUFA intake. However, it may be that the higher level of desaturase activity is not able to overcome the dietary deficit of 22-6 n-3 and 22:6 n-6. Despite the fact that the dietary LCPUFA intake in the pregnant diabetic was comparable with that in the pregnant 'normal' omnivore mothers, the pattern of PUFA in the tissues resembled that of the vegetarian mothers.
69 citations
TL;DR: Platelets were found to emit a burst of chemiluminescence during incubation with arachidonic or linoleic acid, which may indicate activation of the enzyme prostaglandin synthase in the arachidonate-induced platelet chemilumscence as it is inhibited by aspirin.
Abstract: Platelets were found to emit a burst of chemiluminescence during incubation with arachidonic or linoleic acid. This chemiluminescence response may indicate activation of the enzyme prostaglandin synthase in the arachidonate-induced platelet chemiluminescence as it is inhibited by aspirin. Stimulation of platelets with arachidonic acid and linoleic acid induced a concentration dependent chemiluminescence response. Platelets from drug naive schizophrenic subjects showed significantly increased arachidonic acid metabolism compared to control subjects. No significant difference was observed between schizophrenic and control subjects in the chemiluminescence response to linoleic acid. In schizophrenic subjects treated with neuroleptic drugs the overactive arachidonic acid response was normalized. Linoleic acid chemiluminescence response was unaffected by neuroleptic treatment. Hyperactive cyclooxygenase activity may reflect a similar condition in the brain and implicates prostaglandin pathway abnormalities in the pathogenesis of schizophrenia.
TL;DR: The data suggest that EPA/DHA-enriched LDL have decreased oxidative susceptibility and that surface lipids may mediate its rate of oxidation.
Abstract: Enrichment of low density lipoprotein (LDL) with long-chain fatty acids, such as eicosapentaenoic acid (EPA; 20:5 n-3) and docosahexaenoic acid (DHA; 22:6 n-3) found in fish oil, is thought to increase its oxidative susceptibility although such an increase has not been clearly demonstrated. The purpose of this study was to determine the composition and fatty acid concentration of LDL obtained from postmenopausal women given a supplement of fish oil and relate these values to its oxidative susceptibility. Fish oil supplementation significantly increased LDL concentration of EPA (P = 0.0001) and DHA (P = 0.0001) and decreased that of linoleic acid P = 0.006). The concentration of free cholesterol, cholesterol ester, phospholipids and protein was unchanged while triglyceride concentration increased 8% (P = 0.02). Cu2+-mediated oxidation resulted in a shorter lag time, slower oxidation rate and similar concentrations of conjugated dienes of EPA/DHA-enriched LDL than EPA/DHA-unenriched LDL. Stepwise multiple regression indicated that the primary predictor of oxidative susceptibility of LDL was linoleic acid, even after enrichment with EPA and DHA. The oxidation rate of EPA/DHA-unenriched LDL correlated with the cholesteryl ester concentration (P = 0.003) while that of EPA/DHA-enriched correlated with the concentration of phospholipids (P = 0.03). These data suggest that EPA/DHA-enriched LDL have decreased oxidative susceptibility and that surface lipids may mediate its rate of oxidation.
TL;DR: The increase in apoptosis was significantly greater than the contemporary increase in necrosis detected using propidium iodide permeability and was greater than AA effects on normal brain tissue and consistent with activation of the pathways of apoptosis by AA.
Abstract: It has been postulated that loss of proliferative control in tumour cells is a consequence of depletion of cellular arachidonic acid (AA) and that exogenous AA and n-6 fatty acids may restore control of proliferation. To test this hypothesis and to investigate the activity of AA, apoptosis in human primary brain tumour cells was analysed using flow terminal deoxynucleotide transferase uridine nick end-labelling (TUNEL). The effect of exogenous AA (30 microM) was analysed in collagenase-dispersed tissue from seven human primary brain tumours and in the normal brain tissue surrounding one of the tumours. Exogenous AA stimulated apoptosis in tumour tissue. A rapid three-fold increase in endonuclease activity was detected in tumour cells incubated with AA. The increase in apoptosis was significantly greater than the contemporary (< 15%) increase in necrosis detected using propidium iodide permeability and was greater than AA effects on normal brain tissue. These results are consistent with activation of the pathways of apoptosis by AA.
TL;DR: The results indicate that D-002 is a mild anti-inflammatory agent without any ulcerogenic effect associated, and suggest that these effects are probably not mediated through an inhibition of cyclooxygenase, but a reduction in LTB4 levels induced by D-001 could explain these results.
Abstract: D-002 is a natural mixture of high molecular weight alcohols isolated and purified from beeswax, which contains triacontanol among its main components. This study was undertaken to investigate the anti-inflammatory effects of D-002 administered by the oral route in two animal models commonly used in the pharmacological screening of anti-inflammatory drugs. D-002 administered orally to rats (100 and 200 mg/kg) produced a mild but significant reduction of exudate volume in carrageenan-induced pleuritic inflammation that was accompanied by a marked and significant decrease of leukotriene B4 (LTB4) levels in the exudate. D-002 (25, 50 and 200 mg/kg) also significantly diminished the granuloma weight in the cotton pellet granuloma in rats. In both cases, D-002 was less effective than indomethacin, which was used as an established anti-inflammatory reference drug. On the other hand, D-002 administered from 25-1000 mg/kg did not induce erosions or gastromucosal lesions in rats, which differs from results usually obtained with non steroidal anti-inflammatory drugs. These results indicate that D-002 is a mild anti-inflammatory agent without any ulcerogenic effect associated. The results suggest that these effects are probably not mediated through an inhibition of cyclooxygenase, but a reduction in LTB4 levels induced by D-002 could explain these results.
TL;DR: Data show, for the first time, the selective effects of dietary EPA and DHA on T-lymphocyte gene expression.
Abstract: Dietary eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) suppress interleukin-2 (IL-2) secretion and impair T-lymphocyte proliferation. To determine the mechanism of action, mice were fed diets containing either safflower oil (control diet enriched in linoleic acid, 18:2n-6), EPA, DHA or arachidonic acid (20:4n-6). Splenic lymphocytes were isolated and concanavalin A-induced kinetics of IL-2 and IL-2 receptor α mRNA expression were determined by relative competitive-PCR. EPA and DHA did not affect IL-2 mRNA expression but suppressed IL-2 receptor α mRNA levels. These data show, for the first time, the selective effects of dietary EPA and DHA on T-lymphocyte gene expression.
TL;DR: The results suggest that the impairment of D6D activity by vitamin B6 deficiency might be an important factor in decreasing the synthesis of n-6 and n-3 PUFAs in aging, where D 6D activity is already impaired.
Abstract: Delta-6-desaturase (D6D) activity is influenced by many nutritional and non-nutritional factors, among which one of the most important is aging. D6D activity could be susceptible to the dual influence of aging itself and of nutritional deficiencies, due to the reduced intake and/or absorption of essential nutrients. Particularly, vitamin B6 deficiency might be a crucial factor for D6D activity in aged people. Using 20 month old Sprague-Dawley rats fed a diet with a subnormal level of vitamin B6, we evaluated D6D activity for linoleic acid (LA) and alpha-linolenic acid (ALA) in liver microsomes, and the fatty acid composition of microsomal total lipids. We observed a diminished D6D activity for LA and also for ALA in vitamin B6-deficient animals, being approximately 63% and 81% respectively of the corresponding activity in control rats. As a consequence, significant modifications in the relative molar content of microsomal fatty acids were observed. The content of arachidonic and docosahexaenoic acid, the main products of the conversion of LA and ALA respectively, decreased, LA content increased and a decrease in the unsaturation index was observed in liver microsomes of B6-deficient rats. The foregoing results suggest that the impairment of D6D activity by vitamin B6 deficiency might be an important factor in decreasing the synthesis of n-6 and n-3 PUFAs. This may be particularly important in aging, where D6D activity is already impaired.
TL;DR: This is the first report to provide evidence that 8-IP generated in H2O2-exposed PAEC contributes to oxidant-mediated alterations in monolayer barrier function at non-cytotoxic concentrations.
Abstract: The non-enzymatic peroxidation product of arachidonic acid, 8-epi-PGF 2α or 8-isoprostane (8-IP) was measured in H 2 O 2 -exposed cultured pulmonary artery endothelial cell (PAEC) monolayers using a commercially-available enzyme immunoassay kit. H 2 O 2 (50 μM for 1–30 min) significantly increased 8-IP production in a time-dependent fashion. Treatment with higher H 2 O 2 concentrations (100 or 250 μM) failed to further increase 8-IP generation. Determinations of thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxides (LOOH) were not sufficiently sensitive to detect lipid peroxidation in PAEC exposed to 50 μM H 2 O 2 for 15 min. 8-IP (100 pM–500 nM for 2 h) caused PAEC monolayer barrier dysfunction measured as the transmonolayer clearance of albumin without causing significant PAEC cytotoxicity (measured as intracellular lactate dehydrogenase release). This is the first report to provide evidence that 8-IP generated in H 2 O 2 -exposed PAEC contributes to oxidant-mediated alterations in monolayer barrier function at non-cytotoxic concentrations.
TL;DR: In this paper, the authors survey the factors governing the synthesis of prostanoids by the urinary bladder, their role in the maintenance of normal bladder function, the pattern of their secretion in bladder disease and the possible use of prostate cancer in the treatment of bladder pathology.
Abstract: Our knowledge of prostanoids is rapidly increasing. In this review we survey the factors governing the synthesis of prostanoids by the urinary bladder, their role in the maintenance of normal bladder function, the pattern of their secretion in bladder disease and the possible use of prostanoids in the treatment of bladder pathology.
TL;DR: It is demonstrated that 13-HODE downregulates VnR binding with vitronectin (Vn), whereas 12- and 15-HETE upregulate specific Vnr/ligand binding, using purified Vn R/liposomes and purified ligands in an adhesion assay; and that 12-and-15-HetEUpregulate GPIIb/IIIa:liposome binding of Fgn > Fn > Vn.
Abstract: In previous studies, we reported that vascular wall cells such as endothelial cells metabolize linoleic acid to 13-hydroxyoctadecadienoic acid (13-HODE) via the 15-lipoxygenase pathway Endothelial cell 13-HODE levels vary inversely with endothelial cell reactivity to platelets, which, in turn, varies directly with the expression of the vitronectin receptor (VnR) on the apical surface of endothelial cells We and others have also found that tumour cell adhesivity is dependent, in part, upon the relative amounts of intracellular 13-HODE and the arachidonic acid monohydroxide(s), 12- and/or 15-hydroxyeicosatetraenoic acids (12-, 15-HETE) In addition, we and others have found that platelet adhesivity is dependent upon the intraplatelet level of its major lipoxygenase metabolite, 12-HETE Finally, we have demonstrated that 13-HODE and VnR co-localize in nonadhesive endothelial cells but dissociate following endothelial cell injury, at which time, the VnR relocates on the endothelial cell apical surface These data suggest to us that lipoxygenase-derived monohydroxides regulate the ability of various receptors to recognize their specific ligands The latter data also suggest that these monohydroxides act directly by a physiochemical mechanism The present study supports this possibility Thus, we demonstrate that 13-HODE downregulates VnR binding with vitronectin (Vn) > fibronectin (Fn) > fibrinogen (Fgn), whereas 12- and 15-HETE upregulate specific VnR/ligand binding, using purified VnR/liposomes and purified ligands in an adhesion assay; and that 12- and 15-HETE upregulate GPIIb/IIIa:liposome binding of Fgn > Fn > Vn We conclude that cell-specific monohydroxides influence cell-specific receptor-ligand binding directly through a physiochemical mechanism
TL;DR: Results provide convincing evidence that NF-kB may mediate the IL-1beta stimulation of PGHS-2 gene expression as well as the dexamethasone inhibition of the IL -1beta induction process in WISH cells.
Abstract: Interleukin-1β (IL-1β) stimulated PGE2 synthesis in human amnion derived WISH cells, whereas dexamethasone blocked IL-1β-mediated stimulation of PGE2 production. Sequence analysis of the 5′-flanking region of the human prostaglandin H synthase-2 (PGHS-2) gene indicates two putative NF-kB binding sites. Mutation of a single site or both sites resulted in significantly decreased activity of the PGHS-2 promoter. IL-1β treatment increased significantly the native promoter activity and this increase was attenuated by using the NF-kB-mutant promoter. Dexamethasone treatment also decreased the IL-1β mediated stimulation of the PGHS-2 native promoter but not the NF-kB mutant promoter. Furthermore, the involvement of the NF-kB was supported by electrophoretic mobility shift assay which revealed an increased nuclear binding of the NF-kB probe upon IL-1β induction and a decreased nuclear binding of the NF-kB probe upon dexamethasone pre-treatment. These results provide convincing evidence that NF-kB may mediate the IL-1β stimulation of PGHS-2 gene expression as well as the dexamethasone inhibition of the IL-1β induction process in WISH cells.
TL;DR: It is suggested that n-6 fatty acids, and in particular arachidonic acid, modify the membrane environment of the insulin receptor (or the glucose transporters) so that lower levels of insulin are required for glucose homeostasis.
Abstract: Insulin resistance is an important condition which underlies much of the coronary artery disease in affluent societies. We have related insulin resistance, as assessed by fasting plasma insulin, to erythrocyte membrane composition in 54 healthy men and women on a low fat diet. We found a inverse relationship (r = −0.41, P = 0.002) between fasting plasma insulin and the percentage of arachidonic acid in erythrocyte fatty acids. An inverse relationship of similar strength was found with total n-6 fatty acids and a positive relationship was found with the percentage of saturated fatty acids (r = 0.39, P
TL;DR: Stereochemical differences in the ethanolamide group influence the affinity for both cannabinoid receptor subtypes and the signal transduction capabilities of the methanandamide derivatives.
Abstract: Analogs of arachidonylethanolamide (anandamide) were prepared to investigate the structural requirements for ligand binding to and activation of the CB1 and CB2 cannabinoid receptors. The importance of the presence and the placement of the carbonyl was examined with analogs lacking the carbonyl or with the carbonyl amide order reversed. The presence and location of the carbonyl is essential for high-affinity binding to both cannabinoid receptor subtypes, and for determination of signal transduction via G-proteins. Methyl groups were substituted on the 1'- and 2'-positions of arachidonylethanolamide and the significance of chirality was examined. Stereochemical differences in the ethanolamide group influence the affinity for both cannabinoid receptor subtypes and the signal transduction capabilities of the methanandamide derivatives.
TL;DR: It is concluded that the mechanisms by which beta adrenergic stimulation regulates phagocytosis of Candida albicans by HPM appear to be secondary to beta adrenoceptor-mediated hydrolysis of AA accompanied by an increase in PGE2 generation and cAMP production.
Abstract: The mechanisms by which beta adrenergic stimulation regulates phagocytosis of Candida albicans by human peripheral monocytes (HPM) are characterized. Isoproterenol (ISO) inhibits phagocytosis in a concentration-dependent manner. This effect was blunted by propranolol, inhibitors of phospholipase A2 (PLA2), cyclooxygenase and verapamil, pointing to a participation of arachidonic acid (AA) metabolites and calcium in the phenomenon. Prostaglandin E2 (PGE2) and dibutyryl cyclic AMP (db-cAMP) also exerted the same inhibitory effect on phagocytosis. ISO interacts with beta adrenergic receptors of HPM increasing PGE2 and cAMP. We conclude that the mechanisms by which beta adrenergic stimulation regulates phagocytosis of Candida albicans by HPM appear to be secondary to beta adrenoceptor-mediated hydrolysis of AA accompanied by an increase in PGE2 generation and cAMP production. Both PGE2 and cAMP could act as mediators of the inhibitory action of beta agonists on the HPM-phagocytosis process.
TL;DR: It is concluded that GLA and AA interact bactericidally on P. aeruginosa isolates, inducing the development of strains resistant to beta-lactams and to aminoglycosides; their action might be mediated through their peroxides.
Abstract: Based on previous findings that gamma-linolenic acid (GLA) inhibits Escherichia coli growth and provokes the induction of strains resistant to aminoglycosides, 19 Pseudomonas aeruginosa strains were exposed in vitro over time to GLA, to arachidonic acid (AA) and to their combination in the presence or absence of vitamin E. All acids were used at a 300 microg/ml concentration, whereas vitamin E was added as an antioxidant. Lipid peroxidation was evaluated by the thiobarbiturate assay measuring malonodialdehyde (MDA) production. It was found that GLA or AA killed 5-10% of strains at 24 h of growth, whereas when applied in combination their effect involved 100% of strains at 24 h and was limited to 68% of strains in the presence of vitamin E (P< 0.01). MDA production was time-dependent and it was restrained by vitamin E (P < 0.01). Post acid exposure, 27% to 37% of the survived strains became resistant to diverse antimicrobial agents and mainly to ticarcillin, to ceftazidime and to amikacin; no strain developed resistance in the presence of vitamin E. It is concluded that GLA and AA interact bactericidally on P. aeruginosa isolates, inducing the development of strains resistant to beta-lactams and to aminoglycosides; their action might be mediated through their peroxides. Further research is necessary to establish the clinical application of these in vitro findings.
TL;DR: The data suggest therapeutic approaches that may be beneficial in the treatment of I/R injury and shows that the effect of PD-156252 is established through this mode of action, which decreases superoxide and thereby peroxynitrite levels.
Abstract: Endothelins ( ETs ) are potent vasoconstrictors derived from vascular endothelium. They have primary roles in many pathophysiologic states including ischemia/reperfusion (I/R) injury. The relationships between nitric oxide (NO) and ETs are still under investigation. In this study on rats we want to focus on the interaction of NO and ET especially in I/R injury. For this purpose ET-1 and PD-156252, a nonselective ET receptor blocker, were given in a mesenteric I/R model and reactive oxygen species were detected directly using chemiluminescence of the ileal tissue. ET administrations to sham and I/R groups caused significant increases in NO concentrations whereas, in terms of peroxynitrite, which is a highly reactive group of free radicals, its increasing effects were seen only in I/R groups. This suggests that in I/R where superoxide levels increase together with NO, the conversion to peroxynitrite is likely and this effect is augmented with ET administration. On the other hand PD administration decreases superoxide and thereby peroxynitrite levels and this study shows that the effect of PD-156252 is established through this mode of action. These data suggest therapeutic approaches that may be beneficial in the treatment of I/R injury.
TL;DR: The observation that polyunsaturated fatty acids (PUFAs) can inhibit the growth of Helicobacterpylori and heal the ulcer suggest that PUFAs can be exploited as potential anti-peptic ulcer drugs.
Abstract: In patients with duodenal ulcer (DU), the plasma levels of nitrite and lipid peroxides, the anti-oxidant content of red cells and plasma phospholipid fatty acid analysis were performed both before and after healing of the ulcer following treatment with lansoprazole, a proton pump inhibitor. These results showed that during the phase of active DU, the concentrations of antioxidants (superoxide dismutase, SOD, catalase and glutathione peroxidase) in red cells were low where as those of lipid peroxides and nitric oxide were high. Of the fatty acids measured, the concentration of palmitic acid (16:0) was increased during the active ulcer phase whereas those of arachidonic acid, alpha-linolenic acid and docosahexaenoic acid were low. These biochemical abnormalities reverted to normal following healing of the ulcer with lansoprazole. These results coupled with the observation that polyunsaturated fatty acids (PUFAs) can inhibit the growth of Helicobacter pylori and heal the ulcer suggest that free radicals, anti-oxidants, nitric oxide and PUFAs may play a significant role in the pathogenesis of DU. If this is true, it suggests that PUFAs can be exploited as potential anti-peptic ulcer drugs.
TL;DR: It is concluded that seratrodast may attenuate airway hyperresponsiveness, presumably by antagonizing TXA2 released from the inflamed airways.
Abstract: We examined effects of a thromboxane A2 (TXA2) antagonist seratrodast on airway hyperresponsiveness, exhaled nitric oxide (NO), and eosinophils in induced sputum in 14 asthmatics. Subjects were administered 80 mg of seratrodast once a day for 4 weeks. Respiratory conductance (Grs) was measured by the forced oscillation method and airway responsiveness was evaluated as the inhaled dose of methacholine, which induced 35% decrease in Grs. Subjects breathed into a Teflon bag, and NO concentration in the bag was measured by a chemiluminescence analyzer. Induced sputum comprised the entire expectorate produced during a 20 min inhalation of 3% saline, and was analyzed for total and differential cell counts. Airway hyperresponsiveness was significantly decreased by seratrodast. By contrast, no differences in either exhaled NO or percentage of eosinophils in sputum were observed before or after seratrodast. We conclude that seratrodast may attenuate airway hyperresponsiveness, presumably by antagonizing TXA2 released from the inflamed airways.
TL;DR: The data suggest that the effects of consuming NMIFA of JO despite their inability to form eicosanoids are similar to those of feeding EPA which forms biologically active alternate metabolites.
Abstract: Eicosapentaenoic acid (EPA) and the non-methylene interrupted fatty acids (NMIFA) displace arachidonic acid (AA: 20:4omega6 -5,8,11,14) in the membrane phospholipids. Unlike EPA (20:5omega3 -5,8,11,14,17), the NMIFA (20:3omega6 -5,11,14 and 20:4omega3 -5,11,14,17) lacking the delta-8 double bond are not substrates for the formation of eicosanoids. For 20 days, the mice were fed diets containing 5wt% dietary fats from various sources. The magnitudes in the production of eicosanoids and cytokines produced in response to an intraperitoneal injection of endotoxin in mice fed menhaden fish oil (MO) diets enriched with EPA were compared with those maintained on juniper oil (JO) containing NMIFA or on safflower oil (SO), a major source of the AA precursor, linoleic acid. The levels of PGE2, 6-keto-PGF1alpha and TXB2 were markedly lower (P < 0.01) in animals fed either MO or JO diets compared to the controls. The plasma levels of tumor necrosis factor (TNF)-alpha were significantly higher (P < 0.05) with a concomitant decrease of interleukin (IL)-6 and of IL-10 in mice fed MO or JO diets (P < 0.01) compared to those fed SO diet. These data suggest that the effects of consuming NMIFA of JO despite their inability to form eicosanoids are similar to those of feeding EPA which forms biologically active alternate metabolites.
TL;DR: These studies provide further characterization of prostanoid receptor functional responses in three cell types and demonstrate the advantages of a semi-automated RIA method for the analysis of the second messenger cAMP.
Abstract: The aim of these studies was to compare the effects of several prostaglandin agonists on adenylyl cyclase activity in embryonic bovine tracheal (EBTr) cells, transformed human nonpigmented ciliary epithelial (NPE) cells and National Cancer Bank (NCB-20) cells. These cell types have been shown to express DP, EP 2 and IP prostaglandin (PG) receptors, respectively. Cyclic AMP (cAMP) generation was measured by manual and semi-automated radioimmunoassay (RIA) techniques. ZK118182 (EC 50 = 10–27 nM), PGE 2 (EC 50 = 21–27 nM) and PGI 2 (EC 50 = 3.5-4 nM) had the highest potency at the DP, EP 2 and IP receptors, respectively. A plot of potency (EC 50 ) values generated with both techniques showed a high degree of correlation for all three receptors. These studies provide further characterization of prostanoid receptor functional responses in three cell types and demonstrate the advantages of a semi-automated RIA method for the analysis of the second messenger cAMP.
TL;DR: Results suggest that cPLA2 exists in periovulatory follicles and functions in PG production related to the ovulation process and is localized in both thecal and granulosa layers of mature follicles.
Abstract: The preovulatory LH surge induces a remarkable increase in ovarian prostaglandins (PGs) which help to mediate the ovulatory process We investigated whether cytosolic phospholipase A2 (cPLA2) has a role in this PG production in PMSG/hCG-primed immature rats The immunoreactive signal for cPLA2 was localized in both thecal and granulosa layers of mature follicles and became evident in response to gonadotropins The PLA2 activity in the whole ovarian cytosol rose slightly after PMSG stimulation, persisted relatively constant until 24 h after hCG injection and thereafter increased gradually Intra-ovarian bursal injection of arachidonyl trifluoromethyl ketone, a specific inhibitor for cPLA2 ( 10-30 mg/ovary), significantly reduced ovarian PGE2 content and the ovulation rate These results suggest that cPLA2 exists in periovulatory follicles and functions in PG production related to the ovulation process