Certain species of bacteria have been implicated in the etiology and pathogenesis of periodontal diseases. It has been reported that Actinomyces viscosus (A. viscosus) is associated with gingivitis. On the other hand, it is known that prostaglandin (PG) E2 is one of potent mediators of bone resorption and macrophage is PGE2 producing cell. It has been reported that a number of macrophage is increased in inflamed gingival tissues and that A. viscosus (T14V strain) cells significantly stimulated the arachidonic acid (AA) release and the secretion of PGE2 and thromboxane (TX) B2. Furthermore, the level of PGE2 in inflamed gingival tissues was 18 times higher than that of normal gingiva. In general, it is believed that the rate-limiting step in the production of PGs and TXs is dependent on the release of AA from phospholipids in the cell membrane. However, recent papers suggested that the produced levels of PGE2 and TXB2 were not completely dependent on the amounts of released AA, and the mechanism of rate limiting step and the PGE2 production are still remains to be elucidated. It is known that glucocorticoid, anti-inflammatory steroid, inhibits the AA release from phospholipids of cell membrane. In the present study, in order to clarify the mechanism of PGE2 and TXB2 production by the A. viscosus cells, the effect of addition of glucocorticoid on the levels of PGE2 and TXB2 production were studied. The effects of ionophore A 23187 and zymosan, which were known as agents of macrophage activation but having different action manner, on the relation between the AA release and productions of PGE2 and TXB2 were also comparatively studies.(ABSTRACT TRUNCATED AT 250 WORDS)

The purposes of this study were: (1) to investigate which arachidonic acid metabolites contributed to platelet-activating factor (PAF) induced pulmonary dysfunction; and (2) to compare the effect of two non-steroidal anti-inflammatory drugs, phenylbutazone and ketoprofen in a model of PAF-induced reversible lung inflammation in six calves. In placebo and phenylbutazone groups, PAF infusion induced significant dysfunctions in the pattern of breathing, mechanics of breathing and gas exchange. These dysfunctions were prevented by ketoprofen pretreatment, except for the mechanics of breathing which was moderately but significantly altered by the PAF challenge. In all calves, leukotriene (LT) B4 plasma concentrations did not significantly increase above baseline values at any time. Prostaglandin (PG) E2 plasma concentrations showed a minor significant increase in phenylbutazone pretreated calves (55.8 +/- 25.8 pg/mL from 36.7 +/- 16.13 pg/mL). Thromboxane (TX) B2 plasma concentration was significantly increased during PAF challenge in placebo- and phenylbutazone-pretreated groups, but not in ketoprofen-pretreated calves (1580.0 +/- 1370 from 42.7 +/- 10.7 pg/mL; 2340 +/- 477 from 63 +/- 32 pg/mL; and 36.5 +/- 4.12 from 39.3 +/- 12.0 pg/mL, respectively). These data suggest that TXA2 is an important cyclooxygenase metabolite of arachidonic acid produced in response to PAF and that ketoprofen (intramuscular injection, 3 mg/kg) is more effective than phenylbutazone (intramuscular injection, 10 mg/kg) in preventing respiratory dysfunctions induced by the PAF challenge 30 min after drug administration. Ketoprofen did not suppress totally the PAF-induced changes in mechanics of breathing, which suggests that PAF or a secondary release of mediators could have a direct action on airway smooth muscle.

The mechanism of action of FR140423 (3-(difluoromethyl)-1-(4-methoxyphenyl)-5-[4-(methylsulfinyl)phenyl]pyra zole), a novel anti-inflammatory compound, in a rat yeast-induced hyperalgesic model was investigated and compared with those of indomethacin and morphine. We tested the inhibitory effects of FR140423 on the formation of arachidonic acid metabolites, prostaglandin (PG) E2, thromboxane (TX) B2 and leukotriene (LT) B4, in yeast-injected inflamed paws and the effect of the opioid receptor antagonist naloxone on FR140423-induced anti-hyperalgesic effect and inhibition of the formation of arachidonic acid metabolites. Oral administration of FR140423 showed a dose-dependent anti-hyperalgesic effect. This effect was fourfold more potent than that of indomethacin but less potent than that of morphine. Unlike morphine, FR140423 suppressed the levels of PGE2 and TXB2 but not LTB4 in inflamed paws. FR140423 did not inhibit yeast-induced paw edema. The anti-hyperalgesic effect of FR140423 in yeast-injected rat paws was partially blocked by naloxone. However, the inhibitory effects of FR140423 on the formation of PGE2 and TXB2 in yeast-injected rat paws were not antagonized by naloxone. These results suggest that FR140423 shows a potent anti-hyperalgesic effect mediated by inhibition of PGs in inflamed tissue and by activation of opioid receptors.

Since thromboxane (TX) B2 is not a reliable indicator of TXA2 generation in vivo, because of artifactual TXA2 generation during blood collection, we tested the feasibility of replacing TXB2 with 11-dehydro (dh)-TXB2 as the indicator. Plasma levels of TXB2 and 11-dh-TXB2 were measured after i.v. administration of TXB2 to rabbits, guinea pigs, rats, dogs and a monkey, and after i.v. infusion of collagen in rabbits. In the rabbits and dogs, 2,3-dinor-TXB2 levels were also measured. After intravenous injection of TXB2 (10 micrograms/kg) in rabbits, the ratio of the area under the curve (AUC) of 11-dh-TXB2 to that of TXB2 (1.94) was far higher than the AUC ratio between 2,3-dinor-TXB2 and TXB2 (0.42). When endogenous TXA2 was generated by infusion of collagen (2 mg/kg/5 min), the plasma level of 11-dh-TXB2 was significantly increased, and had a longer half-life than TXB2. In the guinea pigs, rats and monkey, the peak plasma levels of 11-dh-TXB2 were significantly increased after injection of TXB2 (10 micrograms/kg, i.v.), whereas the AUC ratios of 11-dh-TXB2/TXB2 were less than one fourth of that in rabbits. No significant increase in 11-dh-TXB2 was observed after TXB2 injection (10 micrograms/kg) in dogs, but the 2,3-dinor-TXB2 level rose significantly, its AUC ratio to TXB2 being 0.29, comparable with that in rabbits. The order of the 11-dh-TXB2/TXB2 AUC ratios was: rabbits>> guinea pigs>> monkey>> rats>>) dogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet-activating factor (PAF) induced contractions of porcine pulmonary vein strips in a concentration-dependent manner, while porcine pulmonary artery strips were unresponsive. Exposure to the specific PAF-antagonists WEB 2086 or BN 52021 antagonized the contractile responses of pulmonary vein strips. Cysteinyl-leukotrienes (LT) and thromboxane (TX) B2 were not detected in the bath fluid after stimulation with PAF suggesting that these eicosanoids as well as their precursors are not mediators of PAF-induced contractions of porcine pulmonary vein strips. Furthermore, PAF had no significant effect on 6-keto-prostaglandin (PG) F1a release and flurbiprofen did not affect the PAF response, while it inhibited the release of 6-keto-PGF1a. This indicates that PGI2 or any other cyclooxygenase product is unlikely to modulate or mediate the PAF response. Incubation experiments with fragments of pulmonary vascular tissues demonstrated spontaneous release of small amounts of cysteinyl-LT, TXB2 and 6-keto-PGF1a, which was significantly increased during incubation in the presence of ionophore A23187. While these results demonstrate the synthesizing capacity of the porcine pulmonary vascular tissues for various eicosanoids, PAF failed to stimulate eicosanoid release under these experimental conditions. We conclude that PAF causes contractions of porcine pulmonary vein strips, which are not mediated by cysteinyl-LT or cyclooxygenase products of arachidonate metabolism. The specific contractile effect of PAF on pulmonary veins, but not arteries, could contribute to the disturbances of the pulmonary circulation observed after injection of PAF or release of endogenous PAF, e.g. after administration of endotoxin.

Modulation of cellular hydroperoxide levels is considered one of the important physiological mechanisms for regulating the synthesis of prostaglandins (PGs) and leukotrienes (LTs) in mammalian cells. Both vitamin E and selenium (Se) have the potential to affect the concentration of peroxides and, thus, the biosynthesis of eicosanoids. To gain insight into some of the molecular mechanisms underlying the regulation of the arachidonic acid cascade by vitamin E and Se, we have investigated the influence of altered vitamin E and Se nutrition on the ability of polymorphonuclear leukocytes (PMNs) derived from endotoxin-challenged lung to secrete arachidonic acid metabolites. Selenium deficiency had no significant effect (p>> 0.05) on lavage fluid levels of thromboxane (TX) B2, LTB4 or LTC4. Vitamin E deficiency, however, led to a significant increase in LTB4 recovered from lavage fluid while having no effect on TXB2. In contrast, Se deficiency, although producing no discernible effects on the production of LTB4, resulted in a significant increase in the release of TXB2 by PMNs. An increase in TXB2 release was seen in both in vitro-stimulated and nonstimulated PMNs. Vitamin E deficiency appeared to induce an enhancement of LTB4 release by PMNs but the increase was not statistically significant. No detectable levels of LTC4 were found in PMN cultures stimulated with either zymosan or A23187. Thus, these studies indicate that deficiencies of either Se or vitamin E lead to alterations in the metabolism of arachidonic acid in the lung.

A method for the preparation of a highly purified sample of rabbit blood monocytes is described. The metabolism of arachidonic acid (AA) in these cells was studied. Mononuclear cells were prepared by centrifugation on Ficoll-Paque gradients and the monocytes were obtained by further centrifugation and adherence onto plastic culture dishes. These procedures provided a preparation which contained 95% monocytes (non-specific esterase positive). Incubation of [1-14C]-AA with these cells produced four major metabolites which were separated by TLC; these corresponded to prostaglandin (PG) D2, thromboxane (TX) B2, 12-hydroxyheptadecatrienoic acid (HHT) and 12-/15-hydroxyeicosatetraenoic acid (HETE). A minor product which co-migrated with PGE2 was also detected but neither 6-keto-PGF1 alpha nor PGF2 alpha were detected. Also, there was no evidence of the formation of 5-lipoxygenase products (5-HETE and LTB4) by rabbit monocytes with or without calcium-ionophore A23187-stimulation. The production of PGD2, TXB2 and PGE2 was further confirmed by analyzing [3H]-AA metabolites using high-performance liquid chromatography (HPLC) with tritiated standards as references. The biosynthesis of these compounds from endogenous substrate in A23187-stimulated monocytes was confirmed by specific radioimmunoassays with or without prior HPLC separation. The synthesis of immunoreactive LTB4 and LTC4 by A23187-stimulated cells was also monitored and found to be relatively low. The synthesis of PGD2, TXB2 and PGE2 from both exogenous and endogenous substrate was suppressed by treatment of the monocytes with indomethacin (10(-6) M).

Application of dimethyl-n- propylsilyl ( DMnPS ) ether derivatives of prostaglandins (PGs) and thromboxane (TX) B2 pentafluorobenzul ( PFB ) esters of negative ion chemical ionization mass spectrometry ( NICIMS ) was investigated. These derivatives were separated completely within 10 min by the use of a fused-silica capillary column coated with methyl silicone. In NICIMS , all of the DMnPS ether derivatives of PGs and TXB2 PFB esters yielded the characteristic negative ion [M - 181]- which was produced by elimination of PFB from the molecule. The detection limit of the DMnPS ether derivative of PGF2 alpha PFB ester was found to be 200 fg with a signal-to-noise ratio of 5 when monitoring the ion of m/z 653 ([M - 181]-) in the high-resolution mode (R = 2500) using ammonia as a reagent gas. The method was applied to the quantitation of PGE2 and PGF2 alpha in an extract obtained from the plasma of a lung-heart preparation from a dog.

The gastric mucosal content of prostaglandin (PG) E2, 6-keto PGF1 alpha, and thromboxane (TX) B2 was determined by radioimmunoassay in unfed rats. The stomach was removed, and gastric mucosal specimens were prepared by microwave irradiation of the 1) intact stomach, 2) frozen stomach, 3) separated frozen glandular portion, 4) frozen gastric mucosa separated from the stomach wall, and 5) separation of frozen gastric mucosa with no microwave irradiation. Procedure 1 resulted in PGE2, TXB2, and 6-keto PGF1 alpha levels of 0.75, 2.33, and 3.04 ng/g tissue in the fundus, and 0.33, 1.92, and 1.76 ng/g tissue in the antrum, respectively. In procedures 2-4 these values were much higher, indicating that the PG content of the gastric mucosa is liable to be changed by various artificial procedures, such as freezing and surgical and mechanical handling. In procedure 5, values of PG contents were quite unreliable. These results suggest that microwave irradiation immediately after removal of the stomach may be the most reliable procedure for the accurate determination of the PG content of the gastric mucosa in vivo.

Urinary excretion and release of prostaglandins (PG) from isolated glomeruli and renal papilla of deoxycorticosterone acetate (DOCA)-treated rats fed with a normal salt (0.6% NaCl) diet and a high salt (4%NaCl) diet were determined. Mean blood pressure was significantly higher in the high salt diet group than in the normal salt diet group (146.2 +/- 2.3 vs 118.6 +/- 1.9 mmHg, p < 0.01). Urinary excretion of thromboxane (Tx) B2, stable metabolite of Tx A2, and 6-keto PG-F1 alpha, a stable metabolite of prostacyclin, increased significantly in the high salt diet group compared to the values of the normal salt diet group increased significantly by 104%, 55%, and 74% compared to those of the normal salt diet group, respectively. Release of 6-keto-PG F1 alpha from renal papilla of the high salt diet group decreased significantly, but there were no intergroup differences in the release of PG E2 and Tx B2. Stepwise multiple linear regression analysis showed that the significant contributory factors underlying the mean blood pressure were urinary excretion of Na (F = 14.187, p < 0.01) and release of Tx B2 from isolated glomeruli (F = 4.135, p < 0.05). These findings suggest that the manifestation of Tx synthesis in renal glomeruli has a predominant role in the salt sensitive pressor response of DOCA salt hypertension in rats.

To assess the roles of vascular prostaglandins in the hypertension of chronic renal failure, the release of prostacyclin and thromboxane (TX) from aorta was evaluated in male Sprague-Dawley rats, the renal mass of which was reduced by removing one kidney and two-thirds of the contralateral kidney ("5/6 nephrectomy"). Five-sixths nephrectomy was followed by significant rises in serum creatinine to 0.55 +/- 0.03 mg/dl and urea nitrogen to 42.9 +/- 3.8 mg/dl, with a concomitant rise in mean blood pressure from 121.6 +/- 1.6 mmHg to 155.3 +/- 8.4 mmHg. In 5/6 nephrectomized rats, the release of TX A2 from aorta, as measured by its stable metabolite TX B2, increased by 60% (p less than 0.01) and prostacyclin, as measured by its stable metabolite 6-keto-prostaglandin, F1 alpha (6-keto-PG F1 alpha) increased by 51% (p less than 0.05). The amounts of both TX B2 and 6-keto-PG F1 alpha released from aorta were closely related to the height of mean blood pressure. These results suggest that the enhanced vasoconstrictor TX production in the vascular walls may be relevant to hypertension in rats with subtotal renal ablation. The adaptive increase in prostacyclin production in the vascular walls may compensate for the elevation of blood pressure due to chronic renal failure in this animal model.

1. The synthesis of prostaglandin (PG) E2, PGF2 alpha, 6-keto-PGF1 alpha and thromboxane (TX) B2 by isolated glomeruli, cortical tubules, inner medullary slices and outer medullary slices was measured in salt-depleted (LNa) rats and in salt-depleted rats receiving captopril (LNa-CEI). Animals were studied before and after 4, 9 and 15 days of Na+ depletion. 2. Na+ balance was reached in LNa rats after 4 days. Blood pressure and creatinine clearance remained stable. Serum Na+ decreased from 140 +/- 1 to 126 +/- 1 mmol/l (mean +/- SEM, P less than 0.01). In contrast, LNa-CEI rats were unable to conserve Na+ adequately: fractional excretion of Na+ and natriuresis were constantly greater than in LNa animals. As a consequence, LNa-CEI rats developed severe hyponatraemia, lost weight and their creatinine clearance decreased. 3. The glomerular synthesis of PGE2, PGF2 alpha and 6-keto-PGF1 alpha, but not of TXB2, was significantly increased in LNa rats. In LNa-CEI rats, the synthesis of PGE2 and 6-keto-PGF1 alpha was similar to control values, but PGF2 alpha and TXB2 synthesis was elevated at day 9. In cortical tubules, PGE2 and PGF2 alpha were unaffected by Na+ depletion, but 6-keto-PGF1 alpha and TXB2 were increased and a similar trend was observed in LNa-CEI rats. In outer medulla of LNa rats, a decrease in all the eicosanoids measured was observed at day 4. In LNa-CEI animals, the synthesis of PGE2 and PGF2 alpha, but not of 6-keto-PGF1 alpha and TXB2, was significantly depressed. In inner medulla, Na+ depletion only tended to decrease PGF2 alpha and 6-keto-PGF1 alpha, but in the presence of captopril, the synthesis of all prostanoids was significantly decreased.

We determined the levels of the stable urinary metabolites of thromboxane A2 and prostacyclin, 11-dehydro-thromboxane B2 (11-dehydro-TXB2) and 2,3-dinor-6-keto-prostaglandin F1alpha (2,3-dinor-6-keto-PGF1alpha) in patients with retinal vascular occlusion (RVO) to elucidate the change of the thromboxane A2/prostacyclin (TX/PGI) ratio with this disease and the effect of low-dose-aspirin therapy. 11-Dehydro-TXB2 and 2,3-dinor-6-keto-PGF1alpha 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 average level of 11-dehydro-TXB2 in 30 patients with RVO was 1038 +/- 958 pg/mg creatinine. It was significantly higher than that of 27 healthy volunteers, which was 616 +/- 294 pg/mg creatinine (p < 0.05 with unpaired t-test). However, 2,3-dinor-6-keto-PGF1alpha levels were not significantly different between these two groups. The average ratio of TX/PGI in the RVO patients was 32 +/- 26 and it was significantly higher than that of healthy volunteers, 17 +/- 10 (p < 0.01). Patients with central retinal artery occlusion or branch retinal artery occlusion showed greatly high 11-dehydro-TXB2 levels and TX/PGI ratios, although the number of patients was limited in the current study. After the administration of low-dose aspirin (40 mg/day) for about 1 month, the TX/PGI ratio decreased to around the normal level. Following the levels for up to 10 months, they also remained at the normal level. These observations suggested that the 11-dehydro-TXB2 levels and the TX/PGI ratio reflect the pathological conditions of RVO and are useful markers of the treatment.

The effects of chronic alterations in dietary sodium intake on urinary prostaglandin (PG) E2 and thromboxane (TX) B2 was investigated in the rabbit. Sodium restriction, over a 15-day period, reduced daily urinary PGE2 and TXB2 in concordance with urinary flow (V) and sodium excretion (UNa+V), but increased plasma renin activity (PRA) and plasma aldosterone concentration (PAC). Sodium repletion, on the other hand, increased urinary PGE2 and TXB2 in proportion to the rise in V, but reduced PRA and PAC. During both sodium diets PGE2 and TXB2 correlated positively with V and negatively with PRA. It is concluded that chronic sodium intake produces opposite changes in the renal prostaglandin and the renin-angiotensin systems.

The hypothalamic paraventricular nucleus (PVN) is one of the most important autonomic control centers in the brain. Several kinds of prostanoids, such as prostaglandin (PG) E2, are considered to act in the PVN as mediators of autonomic responses. In the present study, we used liquid chromatography ion trap tandem mass spectrometry (LC-ITMS(n)) to simultaneously quantify four prostanoids, thromboxane (Tx) B2, PGE2, PGD2 and 15-deoxy-∆(12,14) (15d)-PGJ2 in PVN microdialysates from urethane-anesthetized rats. The quantification limits were estimated to be 0.05ng/mL for TxB2, 0.025ng/mL for PGE2, 0.1ng/mL for PGD2, and 0.5ng/mL for 15d-PGJ2. The RSD% obtained from all prostanoids was <15%, indicating an acceptable level of reproducibility. LC-ITMS(n) analysis of rat PVN microdialysates revealed that TxA2 may play an important role in adrenomedullary outflow evoked by centrally administered N-methyl-d-aspartate, corticotrophin-releasing factor and glucagon-like peptide-1. This is the first study to use LC-ITMS(n) to analyze prostanoid levels in rat PVN microdialysates. This LC-ITMS(n) method will be useful for investigating the potential involvement of prostanoids in brain function.

Isolated rat aortae were perfused with Krebs buffer in vitro and the synthesis of prostacyclin-like material (PGI2-L) was continuously monitored by measuring the contraction of a superperfused rat stomach strip exposed to the aortic perfusate. PGI2-L release was high after initiation of the aorta perfusion but then gradually declined and stabilized at a basal rate of production that was maintained for at least 180 min. Levels of 6 keto prostaglandin F1 alpha(6ketoPGF1 alpha), the stable breakdown product of PGI2, in the aortic perfusate reflected the changes in biological activity. The concentration of PGE2 in the aortic perfusate remained constant throughout the experiment while the level of thromboxane (Tx)B2 (the stable product of TxA2) decreased with time to below the level of detection of the radioimmunoassay (RIA) used. All biological activity was abolished by heating the aortic perfusate for 30 min at 37 degrees C, while perfusing with 30 microM indomethacin inhibited aorta PGI-L formation. Analysis (by linear regression) of the relationship between PGI2-L formation and the body weight or age of the animals used revealed that PGI2-L synthesis was better related to body weight (r2 = 0.90) than age (r2 = 0.75).

Prostanoid production by rabbit choroid plexus (CP) and iris-ciliary body (ICB), and the effects of adrenergic agonists thereon, were studied in vitro. Immunoreactive prostaglandin (PG) E2 was the major prostanoid released by both tissues; the output from ICB was some two orders of magnitude greater than from CP. Immunoreactive 6-keto PGF1 alpha and thromboxane (TX) B2, the dehydration products of prostacyclin and TXA2, respectively, were detected in smaller quantities. Epinephrine stimulated the outputs of PGE2 and 6-keto PGF1 alpha, but not of TXB2, from both tissues. ICB responded to epinephrine concentrations of 10(-4) and 10(-5), while only 10(-4) was effective in stimulating prostanoid synthesis in the CP. Phenylephrine, an adrenergic agonist, stimulated prostanoid output from the ICB, but not from the CP. It is concluded that adrenergic mechanisms stimulate the biosynthesis of prostanoids in the rabbit CP and ICB. The implications of such interactions to aqueous humor and cerebrospinal fluid dynamics, or to other processes in brain and ocular physiology, are discussed.

In the present study, relationship between each level of PGE, TX B2 and 6-keto-PGF1 alpha in the effluent perfusate and vasocontractile response to noradrenaline (NA-R) was examined using the isolated perfused arterial segment of a rabbit ear. The following results were obtained. 1. NA-R was significantly augmented under the conditions infusing either platelet poor plasma (PPP) or platelet rich plasma (PRP), when compared with the control one during perfusion of modified normal Krebs solution (N-R) alone. 2. During PPP infusion, PGE level alone and during PRP infusion, both PGE and TX B2 levels showed significant increment in comparison with the each control ones during perfusion of N-R, respectively. 6-keto-PGF1 alpha level was significantly altered under the conditions infusing neither PPP nor PRP. 3. There was the positively significant correlation between delta NA-R and delta (TX B2/PGE ratio), which represent the difference between the control value during perfusion of N-R and the one during infusion of either PPP or PRP, respectively. From the results obtained, it seems possible to draw the conclusion that the augmentation in NA-R induced by PPP or PRP relates, at least in part, to the secondary alteration of PGE and prostanoids metabolism in the arterial preparation.

The aim of this study was (a) in isolated perfused rat heart to characterize the effects of platelet-activating factor (PAF) on coronary flow, ventricular contractility, and eicosanoid release and (b) to determine whether PAF effects are altered in hearts from spontaneously hypertensive rats (SHR). PAF (10(-10)-10(-7) mol) dose-dependently decreased coronary flow and ventricular contractility; concomitantly, coronary effluent concentrations of thromboxane (TX)B2 and prostaglandin F2 alpha (PGF2 alpha) were elevated but not those of prostacyclin. The PAF receptor antagonist WEB 2086 (10(-7)-10(-5) mol/l) concentration-dependently antagonized these PAF effects. In addition; the cyclo-oxygenase inhibitor indomethacin (5 x 10(-5) mol/l) prevented PAF (10(-9)-10(-7) mol) induced eicosanoid release; in the presence of indomethacin PAF caused coronary constriction and ventricular depression only at the highest dose (10(-7) mol) but had no effect at 10(-9) or 10(-8) mol. Moreover, the TXA2 antagonist SQ29,548 (10(-6) mol/l) completely inhibited 10(-8) mol PAF induced ventricular depression but did not effect coronary constriction. In SHR PAF (10(-9)-10(-7) mol) evoked decreases in coronary flow and ventricular contractility did not differ from those in normotensive Wistar-Kyoto rats while PAF induced TXA2 and PGF2 alpha release was markedly enhanced. In addition, decreases in coronary flow and ventricular contractility induced by the TXA2 agonist U 46619 (10(-7) mol/l) were markedly depressed in SHR. We conclude that in isolated perfused rat heart PAF causes coronary constriction and depression of ventricular function mainly indirectly through released TXA2 and/or PGF2 alpha. Moreover, the fact that in SHR the PAF effects on coronary flow and ventricular function are not altered despite markedly enhanced TXA2 and PGF2 alpha release supports the view that in the SHR the receptors mediating TXA2 and/or PGF2 alpha effects are desensitized.

Rabbit platelets were exposed to a reactive oxygen species (ROS) generating system (xanthine plus xanthine oxidase) to explore the effect of ROS on the formation of 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE), thromboxane (TX) B2, and 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT) from exogenous arachidonic acid. Xanthine plus xanthine oxidase suppressed the production of 12-HETE, TXB2, and HHT by 65-69%. This effect was reversed by addition of catalase to the ROS generating system but not by superoxide dismutase, mannitol, or dimethylsulfoxide, indicating that H2O2 is the responsible metabolite. These results suggest that H2O2 plays an important role in the regulation of platelet cyclo-oxygenase and lipoxygenase activities.

Triple-negative metaplastic breast carcinoma (MBC) poses a significant treatment challenge due to lack of targeted therapies and chemotherapy resistance. We isolated a novel MBC cell line, BAS, which showed a molecular and phenotypic profile different from the only other metaplastic cell model, HS578T cells. To gain insight behind chemotherapeutic resistance, we generated doxorubicin (HS-DOX, BAS-DOX) and paclitaxel (HS-TX, BAS-TX) resistant derivatives of both cell lines. Drug sensitivity assays indicated a truly multidrug resistant (MDR) phenotype. Both BAS-DOX and BAS-TX showed up-regulation of FOXC1 and its experimental down-regulation re-sensitized cells to doxorubicin and paclitaxel. Experimental modulation of FOXC1 expression in MCF-7 and MDA-MB-231 cells corroborated its role in MDR. Genome-wide expression analyses identified gene expression signatures characterized by up-regulation of TGFB2, which encodes cytokine TGF-β2, in both BAS-DOX and BAS-TX cells. Pharmacological inhibition of the TGF-β pathway with galunisertib led to down-regulation of FOXC1 and increase in drug sensitivity in both BAS-DOX and BAS-TX cells. MicroRNA (miR) expression analyses identified high endogenous miR-495-3p levels in BAS cells that were downregulated in both BAS MDR cells. Transient expression of miR-495-3p mimic in BAS-DOX and BAS-TX cells caused downregulation of TGFB2 and FOXC1 and re-sensitized cells to doxorubicin and paclitaxel, whereas miR-495-3p inhibition in BAS cells led to increase in resistance to both drugs and up-regulation of TGFB2 and FOXC1. Together, these data suggest interplay between miR-495-3p, TGF-β2 and FOXC1 regulating MDR in MBC and open the exploration of novel therapeutic strategies.

Keywords: FOXC1; Galunisertib; Metaplastic breast cancer; Multidrug resistance; TGF-β; miR-495-3p.

Mosquito that accountable for dispersal of dengue fever is Aedes aegypti Linn. and considered to be a chief vector for dengue especially in South Asian countries. Aspergillus flavus is considered to be wild growing green yellow colonies and synthesis highly regulating aflatoxins (B1, B2, G1 and G2) as a secondary metabolite. Mycotoxins of A. flavus showed its efficacy against III and IV instars of Ae. aegypti with more than 90% mortality at the prominent dosage of 2 × 10⁸ conidia/ml. The proximate lethal concentrations (LC₅₀ and LC₉₀) of mycotoxins against third and fourth instars was 2 × 10⁵ and 2 × 10⁷ respectively. Correspondingly, sub-lethal dosage of mycotoxin A. flavus significantly inhibited the level of α- β-carboxylesterase and SOD activity and upregulated the level of major detoxifying enzymes GST and CYP450. Moreover, sub-lethal dosage also showed higher deterrent and fecundity effects. Gut-histological examination reveals that the A. flavus considerably affected the gut epithelial cells along with the inner gut lumen as compared to the control. The non-target screening of A. flavus against two aquatic predators (A. bouvieri and Tx. splendens) display more than 80% of mortality rate against both the species at the dosage of 2 × 10¹⁶ (two-fold-higher dosage used in larval assays). Thus the biosafety assessment suggests that A. flavus display higher toxicity against the non-targets and it is not-recommended to apply it directly to the aquatic habitat of dengue mosquito which shares their living space with other beneficial insects.

Plasma levels of the platelet markers beta-thromboglobulin (beta-TG) and platelet factor 4 (PF4) are among the most sophisticated indexes of biocompatibility available to evaluate new members for hemodialysis. This investigation was designed to determine the extent of platelet activation by measuring the alpha-granule release products, beta-TG and PF4; anticoagulation and thrombogenesis by monitoring plasma heparin; and fibrinopeptide A (FPA) and thromboxane B2 (TX B2) levels during treatment with a combined hemodialysis-hemoperfusion system. Both in vivo and in vitro results showed that the platelet markers had a pattern different from that generally observed during treatment with hemodialysis alone. This is due to the avidity of charcoal for the markers studied, which therefore cannot be used to evaluate the biocompatibility of the system.

Background: Recent guidelines only recommend 'vascular dose' rivaroxaban in combination with aspirin in chronic coronary syndrome (CCS) patients with high risk of ischemic events However, in the COMPASS trial, a reduction of MACCE appeared for low-dose rivaroxaban alone compared to aspirin as well. It was recently shown that FXa induces platelet aggregation via protease activated receptor 1 (PAR-1) which is in turn attenuated by rivaroxaban. However, a potential impact of rivaroxaban on TX B2 formation is unclear.Methods and Results: TX B2 levels were measured in supernatant from washed platelets after FXa (52 µg/ml) induced platelet aggregation. TX B2 levels were significantly higher in supernatant from FXa-stimulated platelets compared to unstimulated control (Control 23.53 ± 14.15 ng/ml vs. FXa stimulated 77.4 ± 64.14 ng/ml; p = .0025). This effect was abolished in the presence of 100pM rivaroxaban (Control 23.53 ± 14.15 ng/ml vs. FXa stimulated and rivaroxaban 22.15 ± 24.74 ng/ml; p = .5142). Next, we investigated the effects of 100pM rivaroxaban on platelet aggregation induced by U46619 (TX receptor agonist) using light transmission aggregometry. Platelet aggregation quantified by maximum of aggregation (MoA%) was significantly lower in presence of rivaroxaban (U46619 40.18 ± 20.51% vs. U46619+ rivaroxaban 19.26 ± 15.46%; p = .0274).Conclusion: Our results indicate direct effects of rivaroxaban on the cyclooxygenase-1- TX axis during platelet aggregation. Hence, it seems reasonable that the 'forgotten compass arm' (rivaroxaban alone) might be an alternative to the rivaroxaban plus aspirin combination in CCS patients.

Keywords: Aggregation; aspirin; major adverse cardiovascular and cerebrovascular events; platelet inhibition; rivaroxaban; thromboxane.