Prostaglandins最新文献

Prostaglandin D synthase (PGD synthase) or β-trace protein is a major constituent of human cerebrospinal fluid (CSF) representing ∼3% of the total CSF protein. We have recently developed a highly specific immunofluorometric assay for PGD synthase, which enabled us to quantify the presence of PGD synthase in fluids and tissues not associated with the CNS. In this report we provide quantitative data of the presence of PGD synthase in CSF and serum from 302 subjects with various neurological diseases and symptoms. PGD synthase levels in CSF are approximately 35-fold higher than those of serum, with a median concentration of 11299 μg/L. A statistically significant association of PGD synthase concentration in CSF was observed with both patient age and gender. There was no correlation between PGD synthase concentration in serum and patient age or gender. To evaluate the clinical utility of PGD synthase in diagnosing neurological diseases, the distribution pattern of PGD synthase in CSF and serum was examined for each neuropathology of 268 patients whose diagnosis was known. No statistical difference was observed between PGD synthase concentration in the CSF (129 cases) or the serum (94 cases) of multiple sclerosis afflicted subjects in comparison to all other patients studied. The distribution pattern was also not different for PGD synthase levels in CSF of patients with HIV/AIDS related neuropathies, viral meningitis and fibromyalgia. We conclude that PGD synthase measurement presents no clinical utility in diagnosing neurological disorders in adulthood. PGD synthase may have a physiological and/or pathological role in the developing brain and in neurodegenerative diseases.

To examine the role of Rho family proteins in prostaglandin F_2α (PGF_2α)-mediated phospholipase D (PLD) activation of osteoblast-like cell line MC3T3-E1 cells, we used Toxin B from Clostridium difficile, which inhibits Rho family proteins by monoglucosylation. Pretreatment of [³H]myristic acid-labeled MC3T3-E1 cells with Toxin B induced rounding-up of the cells and inhibited the PGF_2α-induced PLD activation by 60%, but not the phospholipase C (PLC) activation. Cytochalasin D also induced rounding the cells, but showed a small inhibition in the PLD activation. Brefeldin A (BFA) had marginal inhibitory effect on the PGF_2α-induced PLD activation. In digitonin-permeabilized MC3T3-E1 cells, [³H]PBut formation was stimulated by guanosine 5′-O-(3-thiotriphosphate) (GTPγS) or 4β-phorbol 12-myristate 13-acetate (PMA) in the presence of Ca²⁺ (1 μM) and ATP (1 mM), and phosphatidylinositol 4,5-bisphosphate (PIP₂) was also required for its full PLD activation. Pretreatment of the digitonin-permeabilized MC3T3-E1 cells with Toxin B reduced the GTPγS- and PMA-stimulated PLD activities by 80% and 60%, respectively. On the other hand, C3 toxin which inhibits Rho by ADP-ribosylation, exerted a partial inhibitory effect on the GTPγS-stimulated PLD activity. These results suggest that Cdc42 as well as RhoA appear to be involved in the PLD activation mediated by PGF_2α and also that the PLD activation may be independent of actin cytoskeleton in MC3T3-E1 cells.

Platelet functions, including eicosanoid biosynthesis, can be significantly altered by exposure to reactive oxygen species. We utilised the redox properties of the phenazine derivative, pyocyanin, to generate low micromolar levels of reactive oxygen species in order to investigate the metabolism of arachidonic acid by human platelets under oxidative stress. Eicosanoid production by platelets, pre-labelled with [³H]arachidonic acid (AA) and stimulated with the calcium ionophore A23187, was inhibited in the presence of pyocyanin. In contrast, platelets pre-treated with pyocyanin and concurrently exposed to A23187 and AA showed no evidence of inhibition. Analysis of the free label content of labelled, pyocyanin-treated platelets after stimulation revealed diminished levels of total free label and a corresponding increase in labelled phospholipid. Prior treatment with the antioxidants, superoxide dismutase, catalase or the hydroxyl radical scavenger, mannitol, before the addition of pyocyanin afforded protection against loss of eicosanoid production and restored AA release. We conclude that hydroxyl radicals inhibit one or more steps in the cascade leading to phospholipase A₂ activation and release of arachidonic acid from platelet phospholipid stores.

In this study, we analyzed the antioxidative potential (SOD-, GSH-Px-activity) and the basal, H₂O₂- and ATP-stimulated formation of PGI₂ and TXA₂ in human umbilical vein endothelial cells (HUVEC) of different passages. The subcultivation of cells partly represents the process of aging.

Both subcultivation of the cells and the H₂O₂ incubation did not significantly influence the activity of SOD and GSH-Px.

H₂O₂ (0.1 mM and 1.0 mM) stimulated the generation of PGI₂ and TXA₂ in the cell passages time dependently. The formation ratio of PGI₂/TXA₂ changed from 640:1 (0.1 mM H₂O₂) or 430:1 (1.0 mM H₂O₂, 40 min incubation) at the 1st passage, to 13:1 and 17:1, respectively, at the 4th passage. This resulted from the reduction of the PGI₂ synthesis connected with more pronounced TXA₂ formation. The same behavior was found in the basal and ATP-stimulated eicosanoid formation.

Based on this, the age-dependent activation of the oxygen radical formation could be responsible for the modified eicosanoid metabolism resulting in vascular complications in the elderly.

The acute effects of a newly synthesized thromboxane dual blocker (KDI-792), a combined thromboxane synthase inhibitor and receptor antagonist, on lower limb circulation were examined using two-dimensional color and pulse Doppler ultrasonography and laser Doppler flowmetry. A randomized single-masked, placebo-controlled trial was performed on 36 type 2 diabetic patients with minimally impaired baseline flow. The anatomical cross-sectional area (CSA), maximum flow velocity (MFV) and flow volume index (FVI) in the right dorsal pedis artery (DPA) and right femoral artery (FA) were determined by Doppler ultrasonography before and 45 and 90 minutes after the administration of either 100 or 200 mg of KDI-792 to the dose groups or placebo to the control group. Periflux blood flow (PBF) in the right foot was determined simultaneously by laser Doppler flowmetry. Both CSA and MFV in the dose groups were significantly increased in both the FA and DPA. FVI was markedly increased from 21.4 ± 3.7 to 68.3 ± 26.8 in the DPA (M ± SD, P < 0.01) and from 365.4 ± 35.3 to 771.7 ± 75.7 in the FA (P < 0.01) in the 200 mg dose group. In the 100 mg dose group, FVI was markedly increased from 20.0 ± 8.7 to 68.3 ± 26.8 (P < 0.01) in the DPA and from 372.5 ± 130.0 to 677.5 ± 187.8 (P < 0.01) in the FA. PBF was also increased in both dose groups (from 4.15 ± 1.4 to 7.0 ± 4.0 ml/min/100 g tissue in the 200 mg dose group, P < 0.01), whereas there were no significant changes in either measurement in the control group. There were no significant changes in pulse rate or blood pressure after administration in either the dosage group or the placebo group. These and previous findings indicate that a single administration of KDI-792 markedly increases lower limb blood flow and might have a more potent vasodilating effect than that of prostaglandin I₂ derivatives.

We isolated a rat homolog of thromboxane (TX) synthase cDNA (∼ 1.8 kb) from the kidney with a fragment of human TX synthase cDNA amplified by polymerase chain reaction with placenta cDNA as a template. Northern blot analysis has shown that rat TX synthase gene is expressed abundantly in lung, liver, and uterus; moderately in kidney. TX synthase mRNA expression was up-regulated in hydronephrotic kidney made by ureter ligation. In conclusion, we have revealed the structure of rat kidney TX synthase. Up-regulation of renal TX synthase, which may cause stimulation of TX synthesis, is possibly implicated in the tissue injury in hydronephrotic kidney.

We devised a simple and effective purification for the microdetermination of thromboxane B₃ (TXB₃), a hydrolysis product of TXA₃. [¹⁸O₂]TXB₃ was synthesized by the repeated base-catalyzed hydrolysis of methyl ester derivatives in [¹⁸O]water, to obtain an internal standard (IS) for the gas chromatography/selected ion monitoring (GC/SIM) of TXB₃. The methyl ester (ME)-methoxime (MO)-dimethylisopropylsilyl (DMIPS) ether derivative was prepared, then GC/SIM was carried out by monitoring the ion at m/z 668 for TXB₃ and that at m/z 672 for IS. A good linear response over the range of 10 pg ∼ 10 ng was demonstrated. We were able to detect the levels of TXB₃ in the medium of human erythroleukemia (HEL) cell cultured with eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA). This method can be used to determine 3-series thromboxane in biological samples.

Entamoeba histolytica can modulate macrophage functions and cytokine production by a prostaglandin E₂ (PGE₂) mechanism. To study the participation of PGE₂ on amoebic liver abscess formation, we tested the effect of the PG synthesis inhibitor indomethacin (INDO) on abscess development in hamsters infected intrahepatically with E. histolytica trophozoites. Male infected animals had higher levels of plasma PGE₂ (5.7 ± 0.7 pg/ml pre-infection; 26.0 ± 2.0 pg/ml 7 days postinfection; p < 0.001). INDO prevented this increase, so that infected-treated and control non-infected animals had similar levels of plasma PGE₂. INDO reduced liver and abscess weight by 18% and 30% respectively (p < 0.05). Cyclooxygenase (COX) activity determination by thin layer chromatography using (1-¹⁴C) arachidonic acid (AA) showed that liver microsomes from infected animals produced more PGE₂ than controls. COX activity was considerably inhibited in infected INDO-treated animals. Our data suggest that E. histolytica can stimulate the hepatic production of PGE₂ which contributes to pathogenesis of amoebic abscesses through generation and support of the inflammation. The partial effect of INDO treatment suggests that additional factors are involved.

The purpose of this study was to explore whether cyclooxygenase products derived from endothelium or vascular muscle participate in the response of guinea-pig uterine arterial rings to prostaglandin F_2α (PGF_2α). Contraction to PGF_2α (0.1–30 μM) occurred with and without endothelium at similar potency and efficacy (pEC₅₀ (−log EC₅₀) values respectively 5.87 ± 0.06 and 5.97 ± 0.07; maximal response respectively 78.1 ± 1.3% and 76.9 ± 1.5% of contraction induced by 126 mM KCl). Indomethacin (3–30 μM) suppressed the maximum response to PGF_2α and induced a rightward shift of concentration-response curves, regardless of the presence of endothelium. pIC₅₀ values for indomethacin were 4.67 and 4.74 for vessels with and without endothelium, respectively. In contrast, the thromboxane synthesis inhibitor OKY-046 (10 and 100 μM) did not affect the response to PGF_2α. We conclude that the PGF_2α-induced contraction in guinea-pig uterine artery is mediated, at least in part, through constrictor non-thromboxane prostanoid(s) of vascular muscle origin.