To investigate the cellular sources of arachidonate metabolites during asthma, in vitro productions of thromboxane (TX) B2, prostaglandin (PG) D2, leukotriene (LT) B4 and cysteinyl (Cys) LTs from guinea pig eosinophils and macrophages simultaneously stimulated with the Ca ionophore A23187 were investigated. Eosinophils produced high levels of LTB4 and TXB2 and relatively low levels of CysLTs and PGD2. Although macrophages released abundant TXB2 and a little PGD2, 5-lipoxygenase metabolites were below detectable levels. In conclusion, eosinophils produced both cyclooxygenase and 5-lipoxygenase metabolites, while arachidonate metabolism in the macrophages was almost completely inclined toward the cyclooxygenase pathway.

The thromboxane A2/prostacyclin (TX/PGI) ratios were measured in patients with renal diseases to elucidate the relationship between the ratios and the pathological changes of the diseases. Urinary stable metabolites of thromboxane A2 and prostacyclin, 11-dehydro-thromboxane B2 and 2,3-dinor-6-keto-prostaglandin F1alpha, respectively, were converted to 1-methyl ester-propylamide-9,12,15-tris-dimethylisopropylsilyl ether derivative and 1-methyl ester-6-methoxime-9,12,15-tris-dimethylisopropylsilyl ether derivative, respectively, and applied to a gas chromatography/selected ion monitoring. The TX/PGI ratios of 10 outpatients and 6 inpatients with chronic glomerulonephritis were higher than those of 13 healthy volunteers. In an inpatient with systemic lupus erythematoides, the TX/PGI ratios were gradually lowered to the normal level with the therapies. Furthermore, the ratios seemed to change in advance of the changes of the levels of urinary protein and hematuria. These observations suggested that the TX/PGI ratio was a useful index to assess the pathological condition of renal diseases and the effects of treatment.

We examined the early changes after lipopolysaccharide (LPS) injection in chronically alcohol-fed rats with or without splenectomy. Administration of 2 mg/kg body weight LPS caused severe hepatic injury. The plasma aspartate aminotransferase (ASAT) activity was significantly higher in sham-operated rats 8 hr after LPS injection than in splenectomized rats. The plasma tumor necrosis factor (TNF) activity was also significantly higher 1 hr after LPS injection in sham-operated rats than in splenectomized rats. The plasma thromboxane (TX) B2/6-keto-prostaglandin (PG) F1 alpha ratio increased in sham-operated rats after LPS injection. Therefore, the balance of arachidonic acid metabolites was in a hypercoagulated state in sham-operated rats after the LPS injection. Neutrophil infiltration into liver tissue increased in sham-operated rats after the LPS injection. The cytokines and arachidonic acid metabolites released from the spleen after LPS injection in alcohol-fed rats may play important roles in severe hepatic injury.

It has been proposed that ciliary neurotrophic factor (CNTF) belongs to the group of cytokines causing fever in response to infectious and inflammatory noxae. The present investigation was undertaken in the conscious cat to verify whether CNTF (human type, hCNTF) is pyrogenic when given either intravenously (i.v.) or intracerebroventricularly (i.c.v.) and correlate at the same time body temperature with cerebrospinal fluid (CSF) levels of prostaglandin (PG) E2 (i.e., the putative fever mediator in brain) and thromboxane (TX) B2 (the stable TXA2 byproduct) in untreated vs. treated animals. hCNTF (10 microg/kg i.v.; 1 microg i.c.v.) caused fever by both routes and the increase in body temperature was associated with an upward change in CSF PGE2. Conversely, CSF TXB2 showed no elevation. Similarly unaffected was CSF TXB2 by human interleukin 6 (hIL-6, 1 microg i.c.v.), a cytokine with known pyrogenic and PGE2-promoting actions sharing the signal-transducing mechanism with hCNTF. We conclude that CNTF lends itself to a role in the pathogenesis of fever. The modest PGE2 elevation relatively to other cytokines, specifically hIL-1, is ascribed to the fact that CNTF activates the inducible isoform of arachidonate cyclooxygenase, which is constitutively expressed in brain, without concomitantly promoting the formation of new enzyme.

The aim of this study was to investigate whether urinary prostanoids, as an index of renal synthesis of these compounds, are affected in selenium (Se) deficiency and, if so, whether such changes could add to our understanding of the high excretion of ketone bodies in Se-deficient rats (p < 0.005 vs Se-adequate rats). Male rats were fed a Se-deficient diet with less than 0.01 mg Se/kg or the same diet supplemented with 0.2 mg Se/kg. The urinary contents of prostaglandin E2 (PGE2), PGF2 alpha and 6-keto PGF1 alpha were not significantly affected by the Se status. However, there was a positive correlation between the urinary contents of ketone bodies and 6-keto PGF1 alpha in Se deficiency (with p < 0.02 for acetaoacetate and p < 0.05 for 3-hydroxybutyrate). In contrast, only negative (nonsignificant) relationships were observed between these same parameters in Se-adequate rats. No correlations between urinary contents of ketone bodies and PGE2, PGF2 alpha or thromboxane B2 (TXB2) were obtained. Compared to fed rats, starvation caused a 4-fold increase in the urinary TXB2 content in Se-adequate, as well as in Se-deficient rats (p < 0.001). Starvation had an opposite effect on the content of 6-keto PGF1 alpha, which decreased (to 64% that of fed animals p < 0.001) in Se-adequate rats and, nonsignificantly (to 93% that of fed animals) in the Se-deficient group. It is concluded that starvation profoundly affects the urinary contents (and thus, probably renal synthesis) of TX and prostacycline (PGI2).(ABSTRACT TRUNCATED AT 250 WORDS)

Lysine clonixinate is an analgesic drug with a so far unknown mechanism of action. We have determined its effect on platelet cyclooxygenase in man. Biosynthesis of thromboxane (TX)B2 and prostaglandin (PG)F2 alpha in clotting whole blood ex vivo as well as collagen-induced platelet aggregation measured before and at various time points after oral administration of 125 mg lysine clonixinate were compared to results obtained with 500 mg acetylsalicylic acid (ASA). While biosynthesis of both TXB2 and PGF2 alpha measured radioimmunologically was inhibited significantly 2.5 h, but not 6 h, after administration of lysine clonixinate, inhibition by ASA was much greater and still highly significant after 48 h. Similarly, collagen-induced aggregation of platelet-rich plasma was inhibited for a longer period and to a greater extent after administration of ASA than after lysine clonixinate. Our results indicate that lysine clonixinate is a cyclooxygenase inhibitor of moderate potency. It remains to be investigated whether mechanisms other than inhibition of cyclooxygenase contribute to the analgesic activity of lysine clonixinate.

Thromboxane (Tx)B2 and 6-keto-prostaglandin (6-keto-PG) F1 alpha formation in the hippocampus and caudate nucleus were evaluated by microdialysis during and following forebrain ischemia. Spontaneously hypertensive rats were subjected to bilateral carotid artery occlusion with simultaneous hypotension for 8, 14, or 20 min. Dialysate was collected during the ischemic interval and during the reperfusion period. TxB2 and 6-keto-PGF1 alpha levels were measured by radioimmunoassay. In both structures, TxB2 production increased significantly during the reperfusion period in all three ischemic groups. By contrast, increased 6-keto-PGF1 alpha elaboration was observed after only the longest ischemic duration. While TxB2 levels gradually decreased during the 3-h reperfusion period in all groups, the levels in the group subjected to 8 min of ischemia returned to control values most rapidly. A relationship between the duration of ischemia and TxB2 production was therefore evident. 6-Keto-PGF1 alpha levels increased in only the group subjected to 20 min of ischemia and, by contrast to the pattern of TxB2 change, 6-keto-PGF1 alpha levels remained elevated throughout the reperfusion period. During reperfusion, the ratio of TxB2 to 6-keto-PGF1 alpha increased substantially versus the preischemic period in both structures. The data demonstrate that eicosanoid elaboration following cerebral ischemia can be evaluated by the microdialysis technique. In addition, they indicate that the thresholds (duration of ischemia) for the postischemic production and the temporal profiles of TxB2 and 6-keto-PGF1 alpha in the caudate and hippocampus differ. They also demonstrate that there is regional heterogeneity in the patterns of eicosanoid elaboration after forebrain ischemia.

The effects of a newly synthesized compound, SWR-00151 (4-[2-[4-(1H-indol-3-yl)-1-piperidinyl)ethyl]-2(1H)-quinolinone), on experimental Type I allergic models were investigated. Results obtained were as follows: The compound (3 approximately 30 mg/kg, p.o.) dose-dependently inhibited 48-hr passive cutaneous anaphylaxis (PCA) in the rat. From the strong antagonism against the histamine-induced contraction of the isolated guinea pig ileum and the lack of suppressive effect on anaphylactic histamine release from rat peritoneal exudate cells, it is deduced that the compound's inhibitory action against PCA is due to antihistaminic action. Both gamma 1-rich serum- and IgE-rich serum-mediated experimental asthmas in the guinea pig were also considerably inhibited by a small dose (1 mg/kg, p.o.) of the compound. The inhibitory mechanism seems to be almost the same as that of the PCA because the compound did not show any effect on the experimental asthma in guinea pigs pretreated with H1- and H2-antihistaminics. In addition to that, it is well known that the model is largely mediated by anaphylactically released histamine. On the other hand, while ketotifen and oxatomide, which possess potent antihistaminic activity, modestly suppressed a rat experimental asthma SWR-00151 still demonstrated a substantial inhibitory activity, strongly suggesting that histamine does not play an important role in this asthma model. Serotonin was revealed to be partly responsible for the early phase of the reaction by the assessment with methysergide, an antiserotonergic, and SWR-00151 as well as oxatomide and ketotifen showed slight antagonism against serotonin in high concentrations (10(-6) and 10(-5) M) in vitro. When thromboxane (TX) B2 in the plasma was measured during the reaction, significant increased levels of the chemical mediator were found, which were obviously prevented by the treatment with SRW-00151. From these results, SWR-00151 is expected to be a drug effective for the treatment of asthma through mechanisms not only of antihistaminic action but also through inhibition of anaphylactic formation/release of other mediators like TXA2.

We established microdetermination methods of prostaglandin (PG) metabolites by GC-selected ion monitoring (GC-SIM) and applied them to the clinical investigations. At first the microdetermination of delta 17-6-keto-PGF1 alpha, a hydrolyzed metabolite of PGI2, is described. An authentic delta 17-6-keto-PGF1 alpha was prepared from eicosapentaenoic acid (EPA) incubated with a homogenate from the bovine aortic intima. [18O] delta 17-6-Keto-PGF1 alpha was synthesized to obtain an internal standard for GC-SIM of delta 17-6-keto-PGF1 alpha. A good linear response over the range of 10 pg-5 ng was demonstrated. Chromatographic conditions using a MP-65HT column presented nearly baseline separation of delta 17-6-keto-PGF1 alpha and 6-keto-PGF1 alpha. Furthermore, a monoclonal antibody against cis-3-hexen-1-ol was prepared and used to separate and/or concentrate delta 17-6-keto-PGF1 alpha in the human blood sera. Using the prepared immunoaffinity columns of this antibody, delta 17-6-keto-PGF1 alpha was clearly detected in the human blood sera by GC/MS analysis. We were able to detect delta 17-6-keto-PGF1 alpha of the amount ranging from 6 to 26 pg/ml in the human blood plasma. The present method can be applied to the determination of delta 17-6-keto-PGF1 alpha in the human urine and plasma. Diabetes mellitus induces platelet alterations such as hyperaggregation. Variations in PG production seem to be related to this phenomenon but the changes in PG levels remain unclear. So we microanalyzed the 11-dehydrothromboxane B2 (TXB2) and 2,3-dinor-6-keto-PGF1 alpha, which were stable metabolites of TXA2 and PGI2, in the urine and investigated the relationship between the thromboxane/prostacyclin (TX/PGI) ratio and diabetes mellitus. The TX/PGI ratio in the urine of diabetics was higher than that of healthy volunteers. In murine, the TX/PGI ratio of STZ-induced mice was also higher than that of non-induced mice. The ratio of db/db mice also increased with the progress of diabetes mellitus. Furthermore, we investigated the relationship between the retinal vein occlusion (RVO), a thrombotic disease in which the retinal vein is blocked by blood aggregations, and the TX/PGI ratio. The TX/PGI level in patients with the RVO, who were not combine diabetes, was significantly higher than that in healthy volunteers. One of the causes of the RVO may be due to the variation of thromboxane production. This GC-SIM method can be used to determine the TX/PGI ratio in the urine.

10(-6) and 10(-5) M spironolactone decreased the total conversion of 14C-arachidonic acid to 6-keto-prostaglandin (PG) F1 alpha, PGE2 and PGF2 alpha in rat aortic and mesenteric artery rings by 29 and 55% respectively. Same concentrations of spironolactone decreased the total conversion of 14C-arachidonic acid to thromboxane (TX) B2, PGE2 and PGF2 alpha in human platelets by 3 and 21% respectively. These findings provide a possible basis for the significant inhibition by spironolactone of vascular reactivity to norepinephrine. Spironolactone seemed to act in both vascular tissue and platelets to suppress PG synthesis at the prostaglandin endoperoxide synthetase level. This direct action of spironolactone could contribute to its vascular and other effects.

The aim of the study was to investigate the influence of calcium blockers on the prostaglandin system of blood platelets and the vessel wall with respect to a possible beneficial effect on atherosclerosis. The influence of diltiazem, isradipine, nifedipine and verapamil was examined on ADP- and collagen-induced in vitro platelet aggregation, platelet malondialdehyde formation and other platelet function tests. All the calcium blockers investigated inhibited platelet activation in a dose-dependent manner, isradipine being the most effective. Malondialdehyde formation (measured photometrically) and thromboxane (TX) B2 production were decreased too. Vascular tissue PG12 formation was investigated in rat aortic rings (6-oxo-PGF1 alpha-RIA). PG12 formation was enhanced by all the calcium blockers investigated (p less than 0.01), isradipine again having the most pronounced effect. Platelet adenylate cyclase was stimulated by diltiazem only (RIA, HPLC). Ex vivo ADP-, collagen- and epinephrine-induced platelet aggregation and serum TX were studied 90 minutes after ingestion to diltiazem (60 mg), nifedipine (20 mg) and verapamil (40 mg). ADP- and epinephrine-induced platelet aggregation (19-36%) and serum TX were reduced significantly (p less than 0.01), but collagen-induced aggregation was not significantly affected. These results suggest a possibly beneficial effect of calcium blockers on atherosclerosis via the prostaglandin system.

Sliced portions of the walls of human aortic aneurysms were incubated with extracts of human plasma and serum to determine the profile of prostanoid production. 6-Oxo-prostaglandin (PG) F1 alpha, PGE2, PGF2 alpha, and thromboxane (TX) B2 were measured by gas chromatography/electron capture mass spectrometry. 6-Oxo-PGF1 alpha, the stable hydrolysis product of PGI2, was the major cyclooxygenase product but substantial amounts of TXB2 (the hydrolysis product of TXA2), with smaller amounts of PGE2 and PGF2 alpha were also synthesised. These prostanoids could contribute to the response of the vascular wall to injury, thereby influencing the disease process. Serum extracts stimulated PGI2 and TXA2 synthesis, probably as a result of their Ca2+ content.

The aim of the present study was to investigate the serum levels of 6-keto-prostaglandin (PG)F1α and thromboxane (TX)B2, as well as the endothelialization and hyperplasia of polytetrafluoroethylene (PTFE) and Dacron prostheses seeded with CD34+ cells in medium-term observation. A total of 24 crossbred dogs were randomly distributed into PTFE or Dacron groups. CD34+ cells were isolated from bone marrow aspirate and collected using an immunomagnetic bead-based system. The PTFE or Dacron prostheses were implanted into the abdominal aortic artery and inferior vena cava of the dogs. In each group, 8 dogs were implanted with prostheses that had been seeded with CD34+ cells, while 4 dogs were implanted with prostheses that had been seeded with autogenous blood as a control. Serum concentrations of 6-keto-PGF1α and TXB2 were determined at days 0, 10, 30 and 60 following surgery. The grafts were removed and examined at days 10, 30, 60 and 100 following surgery. Finally, CD34 factor staining was used to identify endothelial cells, while light and electron microscopy were applied to examine endothelialization and patency. The results revealed that confluent endothelial cells appeared on the neointima of prostheses seeded with CD34+ cells at day 30 following surgery. In the control groups compared with the experimental groups, there were fewer endothelial cells and the neointima was significantly thicker in the arterial (PTFE, 174±1.41 vs. 117±2.83 μm, respectively; P=0.001; Dacron, 187.5±3.5 vs. 100±1.41 μm, respectively; P<0.001) and venous (PTFE, 230.5±6.36 vs. 135±5.66 μm, respectively; P=0.001; Dacron, 249±2.83 vs. 121.5±3.54 μm, respectively; P<0.001) prostheses. In the experimental groups, intimal hyperplasia in the venous prostheses (PTFE, 135±5.66 μm; Dacron, 121.5±3.54 μm) was more severe compared with that in the arterial prostheses (PTFE, 117±2.83 μm; Dacron, 100±1.41 μm) at day 60. Compared with the 6-keto-PGF1α concentrations in the experimental groups, those in the control groups were significantly lower on day 10 (PTFE, 135±6.01 vs. 80.5±4.35 pg/l, respectively; P=0.001; Dacron, 145±6.54 vs. 81.2±5.10 pg/l, respectively; P<0.001) and were then maintained at a lower level. By contrast, the TXB2 concentration, following marked increases on day 10 in the experimental and control groups (PTFE, 635±32.8 vs. 1,256±63.5 pg/l, respectively; P<0.001; Dacron, 652±30.9 vs. 1,136±53.2 pg/l, respectively; P=0.001), remained at a high level in the control groups. Therefore, the results of the present study indicate that it is possible to achieve rapid endothelialization in PTFE or Dacron prostheses by implanting CD34+ cells. Endothelialization inhibited the reduction in the concentration of 6-keto-PGF1α and the increase in the concentration of TXB2. In addition, endothelialization inhibited excessive intimal hyperplasia and thrombosis. Thus, CD34+ cell seeding provides a theoretical basis for the clinical application of artificial vessel endothelialization.

Conflicting results have been reported regarding the effect of thiopental on aggregation and cytosolic calcium levels in platelets. The present study attempted to clarify these phenomena. Using platelet-rich plasma or washed suspensions, platelet aggregation, thromboxane (TX) B2 formation, arachidonic acid (AA) release, and cytosolic free calcium concentrations ([Ca2+]i) were measured in the presence or absence of thiopental (30-300 microM). Platelet activation was induced by adenosine diphosphate (ADP, 0.5-15 microM), epinephrine (0.1-20 microM) arachidonic acid (0.5-1.5 mM), or (+)-9,11-epithia-11,12-methano-TXA2 (STA2, 30-500 nM). Measurements of primary aggregation were performed in the presence of indomethacin (10 microM). Low concentrations of ADP and epinephrine, which did not induce secondary aggregation in a control study, induced strong secondary aggregation in the presence of thiopental >> or = 100 microM). Thiopental >> or = 100 microM) also increased the TXB2 formation induced by ADP and epinephrine. Thiopental (300 microM) increased ADP- and epinephrine-induced 3H-AA release. Thiopental (300 microM) also augmented the ADP- and epinephrine-induced increases in [Ca2+]i in the presence of indomethacin. Thiopental appears to enhance ADP- and epinephrine-induced secondary platelet aggregation by increasing AA release during primary aggregation, possibly by the activation of phospholipase A2.

Anethole dithiolthione (ADT) (10 mumol/l) inhibited platelet aggregation and the formation of thromboxane (Tx)B2 in plasma in response to adenosine diphosphate (ADP), epinephrine and arachidonic acid (AA). ADT partially inhibited platelet aggregation and TxB2 formation in plasma induced by thrombin, phorbol myristate acetate and calcium ionophore A23187 and increased the lag time of collagen-induced aggregation at concentrations in the range 10-40 mumol/l. ADT (100 mumol/l) completely inhibited the aggregation of washed platelets challenged with thrombin. ADT had no additive effect on the inhibition of thrombin-induced platelet aggregation by acetylsalicylic acid. ADT was a more effective inhibitor of AA-induced platelet aggregation than butylated hydroxytoluene. ADT inhibited the release of 3H-AA from platelet phospholipids in response to ADP and collagen. It is suggested that ADT inhibits platelet aggregation by inhibiting thromboxane synthesis and preventing AA release.

Defibrotide (DF) has been proposed as a new antithrombotic agent in renal transplantation. Because it was also found to increase prostacyclin synthesis, a reduction in ciclosporin (CS) nephrotoxicity could be supposed. To ascertain this hypothesis, renal function and urinary prostanoids were evaluated in four groups of rats after 10 days of oral treatment (doses in mg/kg/day): CS 50 (group A), CS 50 + DF 400 (group B), DF 400 (group C) and controls (group D). Compared to controls, creatinine clearance (CCR) was significantly lower in groups A and B (In CCr: A = 6.62 +/- 0.28, B = 6.83 +/- 0.24 vs. 8.17 +/- 0.13 microliters/min, p less than 0.01), whereas it did not change in group C (8.03 +/- 0.24 microliters/min). The urinary excretion of prostaglandin E2 (PGE2) was significantly (p less than 0.05) higher in group A (In PGE2: 3.98 +/- 0.98 nmol/mol Cr) and more evidently in groups B and C (6.89 +/- 0.38 and 6.01 +/- 0.32 nmol/mol Cr, respectively) compared to controls (1.43 +/- 0.45 nmol/mol Cr). The urinary excretion of 6-keto-PGF1 alpha and of thromboxane B2 (TxB2) were higher only in groups A and B (ln 6-keto-PGF1 alpha and ln TxB2: A = 6.45 +/- 0.22 and 4.97 +/- 0.20, B = 7.06 +/- 0.31 and 5.43 +/- 0.41 vs. group D = 5.53 +/- 0.22 and 3.79 +/- 0.42 nmol/mol Cr; p less than 0.05). The 6-keto-PGF1 alpha/Tx molar ratio was not significantly affected, although a trend for a reduction in the ratio was found in the treated rats.(ABSTRACT TRUNCATED AT 250 WORDS)

The relationship of bradykinin and cholecystokinin (CCK) to inflamed gallbladder prostanoid synthesis and release was examined in rabbits treated with common bile duct ligation (BDL) for 24 or 72 h. Gallbladders removed from control and BDL groups were incubated in oxygenated Krebs buffer at 37 degrees C (pH 7.4) for 60 min. The slices were then placed every 20 min in vials containing increasing doses of bradykinin (30-3000 ng) or CCK (30-1000 ng). Incubation fluid was analyzed by RIA for 6-keto-prostaglandin (PG)F1 alpha (PGI2 metabolite), PGE2 and thromboxane (TX) B2. Bradykinin stimulated control gallbladder 6-keto-PGF1 alpha and PGE2 release was modest. Gallbladders from 24- and 72-h BDL groups released 3- to 10-fold higher levels of 6-keto-PGF1 alpha and PGE2 (not TXB2) following bradykinin stimulation when compared to controls, which was abolished with indomethacin pretreatment. CCK did not stimulate gallbladder prostanoid release in the control or BDL groups. These data show that bradykinin and not CCK stimulated PGI2 and PGE2 release from inflamed rabbit gallbladder. Increased BDL gallbladder PGI2 release may be prolonged or augmented by bradykinin as gallbladder distention and progressive acute inflammation stimulate local bradykinin formation.

In decidual tissues of first trimester therapeutic abortions we have identified a large macrophage population that is stained by a specific antibody (Ki-M8). Also, we evaluated the capacity of decidual cells, obtained before and after labor, to synthesize prostanoids from radiolabeled arachidonic acid. Decidua collected after vaginal delivery produced significantly more prostaglandin (PG) F2 alpha, PGE2 and thromboxane (TX) B2 (7.4 +/- 1.3, 7.2 +/- 1.3, 11.7 +/- 1.1 pmol/mg protein/4 h, mean +/- SD, respectively) than did tissues from women who had caesarean sections (3.3 +/- 0.8, 1.4 +/- 0.5, 6.3 +/- 1.8 pmol/mg protein/4 h, respectively). Moreover, PGF2 alpha and PGE2 were rapidly converted to their 13,14-dihydro-15-keto-metabolites particularly in tissues obtained after vaginal delivery. All this lends further support to the proposition that decidual activation may be important in the onset of labor.

Stimulation of bovine alveolar macrophages with calcium ionophore A23187 resulted in marked production of leukotriene (LT)B4 and a lesser increase in thromboxane (TX)B2, whereas opsonized zymosan (OPZ) resulted in production of TXB2 and relatively small increases in LTB4 and prostaglandin (PG)F2 alpha. Alveolar macrophages incubated with recombinant bovine interferon-gamma or lipopolysaccharide, and subsequently stimulated with A23187 or OPZ, had altered arachidonic acid metabolism, producing markedly increased amounts of TXB2 and PGF2 alpha, and slightly increased LTB4. Incubation of alveolar macrophages with lipopolysaccharide had a more profound effect on the increased amounts of TXB2 and PGF2 alpha, observed in response to stimulation with A23187 or OPZ, than did incubation with interferon-gamma. Alveolar macrophages incubated with recombinant bovine interferon-alpha 1-1 also produced slightly increased amounts of LTB4 when stimulated with A23187 or OPZ. Altered arachidonic acid metabolism by alveolar macrophages exposed to interferons and lipopolysaccharide may contribute to the development of pulmonary inflammation, such as in the early stages of bacterial pneumonia following viral infections that induce interferon production.

Ultrafine metal oxides and SO2 react during coal combustion or smelting operations to form primary emissions coated with an acidic SOx layer. Ongoing work in this laboratory has examined the effects of sulfur oxides on pulmonary functions of guinea pigs. We have previously reported that 20 micrograms/m3 acidic sulfur oxide as a surface layer on ultrafine ZnO particles decreases lung volumes, decreases carbon monoxide diffusing capacity, and causes lung inflammation in guinea pigs after 4 daily 3-h exposures. It also produces bronchial hypersensitivity following a single 1-h exposure. The importance of this surface layer is demonstrated by our observation that 200 micrograms/m3 of sulfuric acid droplets of equivalent size are needed to produce the same degree of hypersensitivity. This study characterized the concentration-dependent effects of in vivo exposures to sulfur oxides on arachidonic acid metabolism in the guinea pig lung, and investigated the time course and the relation between eicosanoid composition and pulmonary functions. We focused specifically on four cyclooxygenase metabolites of arachidonic acid, that is, prostaglandins (PG) E1, F2 alpha, 6-keto prostaglandin F1 alpha, and thromboxane (Tx) B2, and two groups of sulfidopeptide leukotrienes (C4, D4, E4, and F4). Guinea pigs were exposed to ultrafine ZnO aerosol (count median diameter = 0.05 microns, sigma g = 1.80) with a layer of acidic sulfur oxide on the surface of the particles. Lung lavage was collected after exposures, and the levels of arachidonic acid metabolites were determined using radioimmunoassay (RIA). Concentration-dependent promotion of PGF2 alpha and concentration-dependent suppression of LtB4 were observed. The increased PGF2 alpha was associated with depressed vital capacity and diffusing capacity of the lungs measured in guinea pigs exposed to the same atmosphere described in a previous study. There is no causal relationship between the levels of other arachidonic acid metabolites and the pulmonary functional changes after exposures to these aerosols.

In order to investigate the production of eicosanoids in human endometrium, myometrium, leiomyoma, adenomyosis, normal ovary, non-endometrial cyst and endometrial cyst, slices of each tissue were incubated. 6-Keto-prostaglandin (PG) F1 alpha, thromboxane (TX) B2, PGF2 alpha and PGE2 concentrations in the incubation medium were measured by direct RIA. 6-Keto-PGF1 alpha production of adenomyosis was significantly higher than that of endometrium, myometrium and leiomyoma, especially in the menstrual phase. The production of eicosanoids in endometrial cyst was significantly higher than that of non-endometrial cyst and normal ovary. These results suggest that endometriosis is associated with increased eicosanoid production in vivo.

We explored the temporal and topographic relations between local cerebral blood flow and regional brain prostaglandin profile following prolonged or transient occlusion of the middle cerebral artery in cats. Each experimental group was subjected to a sham operation, prolonged ischemia, or recirculation. Local cerebral blood flow was measured by the hydrogen clearance method. Following in situ freezing, cortical samples were obtained from each gyrus for determination of prostaglandin (PG) F2 alpha, PGE2, 6-keto-PGF1 alpha, and thromboxane (TX) B2 concentrations by radioimmunoassay. During prolonged ischemia, the concentrations of PGF2 alpha and PGE2 within the middle cerebral artery territory were significantly increased. Immediately after recirculation, there was a prominent but transient increase in PGF2 alpha and PGE2 in gyri that had been exposed to moderate ischemia (perifocal area). By contrast, the increases in these prostaglandins were slow and less prominent in gyri that had been exposed to severe ischemia (the focal area). The concentration of 6-keto-PGF1 alpha did not change during prolonged ischemia but transiently increased following recirculation in both the focal and perifocal areas. The TXB2 concentration did not change in any experimental group. Our study revealed a homogeneous increase in the regional brain content of PGE2 or PGF2 alpha in spite of the heterogeneous reduction of local cerebral blood flow during prolonged ischemia. Following recirculation, the focal and perifocal areas exhibited different patterns of prostanoid content. No correlation was found between local cerebral blood flow and the regional concentration of any prostaglandin examined.

Introduction: Tegaserod, an orally active, potent 5-hydroxytryptamine-4 serotonin receptor agonist, was previously indicated for irritable bowel syndrome but was voluntarily withdrawn due to potential cardiovascular side effects. In vitro studies suggested that tegaserod increased platelet aggregation, but these results were not reproduced or were inconclusive. We sought to assess ex vivo effects of tegaserod on platelet aggregation.

Methods: In this double-blind, placebo-controlled, crossover study, we randomized a majority of healthy patients with no history of cardiovascular risk factors (n = 21) to receive tegaserod or matching placebo for 7 + 2 days followed by a 7- to 10-day washout period, and then patients were crossed over to the other study drug for the next 7 + 2 days. Unstimulated and agonist-stimulated platelet aggregation; P-selectin expression; serum thromboxane (Tx)B₂ and urinary 11-dehydro (11-dh) TxB₂; and tegaserod and M29.0 concentrations were serially assessed.

Results: There was no significant difference in percentage change in unstimulated or adenosine diphosphate (ADP)- and ADP + serotonin-, collagen- and thrombin receptor activating peptide-induced maximum platelet aggregation and in platelet P-selectin expression in the presence of tegaserod at any time point when compared to placebo. Similarly, there was no significant difference in percentage change in serum TxB₂ or urinary 11-dhTxB₂ levels between placebo and tegaserod. No new or unexpected findings were observed in evaluations of safety or pharmacokinetic parameters.

Conclusion: This comprehensive pharmacodynamic study, by employing established markers used in prior investigations, which have been considered by the Food and Drug Administration to indicate drug-related platelet effects, does not demonstrate any influence of tegaserod treatment on platelet function.

Keywords: P-selectin; platelet aggregation; serum thromboxane B2; tegaserod; urinary 11-dehydro thromboxane B2.

When 50 mg CS-518, a novel thromboxane (TX) A2 synthase inhibitor, was orally administered to healthy male volunteers, the plasma concentration of CS-518 peaked after 0.5 h and then decreased with a half-life of 0.44 h. There was no significant change in the plasma concentration of circulating TXB2, whereas that of circulating 11-dehydrothromboxane B2 (11-dhTXB2), an enzymatic metabolite of TXB2, was significantly decreased from 0.5 h to 24 h after administration; the maximal decrease to about 25% of the pre-dose value was found at 6 h. After CS-518 100 mg b.d. for 4.5 days, plasma 11-dhTXB2 was suppressed to the same extent as after the single dose of 50 mg from 6 h after the initial dose throughout the administration period. The urinary excretion of 11-dhTXB2 corrected for the creatinine level was significantly decreased by 70-84% throughout the treatment. These results suggest that CS-518 causes long-lasting inhibition of TXA2 synthase despite its rapid elimination from plasma, and that circulating 11-dhTXB2 in plasma and its urinary excretion can serve as a quantitative index of TXA2 synthase inhibition in vivo by CS-518.