Effect of positive and negative emotion on stimulus-preceding negativity prior to feedback stimuli.

Stimulus-preceding negativity (SPN) was recorded to investigate the effect of positive and negative emotion on the SPN preceding feedback stimuli. In the time-estimation task in which an acoustic stimulus was presented 3 s after a voluntary movement, (1) the negative valence (aversive band noise and pure tone) and (2) the positive valence (reward and no-reward) of feedback stimuli were manipulated. During noise conditions, participants received the band noise as a feedback stimulus except when their time estimations were accurate. They received a monetary reward for accurate time estimations under the reward conditions. The prefeedback SPN was larger under reward than no-reward conditions. In addition, the prefeedback SPN in the noise condition was larger compared with the pure tone condition. Our results appear to suggest that emotional anticipation is important in eliciting the prefeedback SPN.

Effect of ozagrel on locomotor and motor coordination after transient cerebral ischemia in experimental animal models.

The effect of ozagrel, a selective thromboxane A(2) (TXA(2)) synthetase inhibitor, on the obstruction after cerebral ischemia-reperfusion was studied in experimental animal models. The reduced spontaneously locomotor activity and the obstruction of motor coordination were improved by the administration of ozagrel in the conscious cerebral ischemia-reperfusion mouse model. Ozagrel suppressed the decrease in specific gravity of the brain tissue induced by the occlusion-reperfusion in the conscious cerebral ischemia-reperfusion SHR model, and recovered the postischemic decrease in cortical PO(2) after middle cerebral artery occlusion-reperfusion in cats. The level of TXB(2), a metabolite of TXA(2), in the brain increased after the cerebral ischemia-reperfusion, and ozagrel prevented this increase. Additionally, ozagrel also increased the level of 6-keto-PGF(1alpha), a metabolite of prostaglandin I(2) (PGI(2)), in the brain tissue after cerebral ischemia-reperfusion, and the administration of PGI(2) improved the reduced spontaneous locomotor activity in the conscious cerebral ischemia-reperfusion mouse model. Our data suggest that ozagrel suppressed the obstruction following cerebral ischemia-reperfusion by preserving the cerebral blood flow via preventing the increase in TXA(2) and causing an increase in the PGI(2) level.

Microdetermination of the thromboxane B3 gas chromatography-selected-ion monitoring using [18O]thromboxane B3 as an internal standard.

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 approximately 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.

The psychological factors of a premature response based on contingent negative variation.

The psychological factors of a premature response on simple reaction-time tasks were examined by comparing the difference between control responses (33 samples) and premature responses (33 samples) using the index of Contingent Negative Variation (CNV). The first (warning) stimulus was a click, the second (imperative) stimulus was a colored circular figure presented on a CRT, and the interstimulus interval was set at 3 sec. 72 trials were administered to the 24 subjects, then 33 artifact-free CNV data in a premature response were shown. Analyses indicated that CNV amplitudes in the premature response were lower than those in the control response at frontal position. Especially in the premature response, CNV waveforms stayed around baseline toward S2 at F3 and F4. In the analyses of variance, every CNV component (early, late, and whole components) at F4 or FZ was significantly lower for the premature response. These results suggested that the optimal prediction, arousal, and attention do not seem to be maintained in a premature response.

Effects on contingent negative variation of set created by anticipating variable foreperiods.

The influence of set on a simple reaction time task was examined by comparing the differences of psychological factors between a group of subjects who expected and experienced a fixed foreperiod Control condition: 12 subjects) and another group of subjects who were instructed to expect variable foreperiods but experienced the same fixed foreperiod (Instruction condition: 11 subjects), using the index of contingent negative variation (CNV). The foreperiod of simple reaction time task in each condition was fixed at 3 sec. Subjects were required to respond to 2 blocks of 24 trials, and each instruction was presented between blocks. On the second block CNV amplitudes were higher in the instruction condition as was every CNV component (early late, and whole component). The set created by anticipating variable foreperiods seems to increase cerebral activity, arousal, and attention during simple reaction time tasks.

A highly sensitive and selective method for the determination of Leukotriene B4 in human plasma by negative ion chemical ionization/gas chromatography/tandem mass spectrometry.

We have developed a highly sensitive and highly selective method for the determination of Leukotriene B4 (LTB4) in human plasma using negative ion chemical ionization/gas chromatography/tandem mass spectrometry (NICI/GS/MS/MS) analysis. The developed method was summarized as follows. Deuterated LTB4 (d4-LTB4) was added to human plasma samples as an internal standard, and samples were extracted by a Sep-pak C18 column. Extracted LTB4 was derivatized into the pentafluorobenzyl ester of bis-trimethylsilyl ether (PFB-TMS-LTB4) and quantified on the basis of selected reaction monitoring (SRM) at m/z 299 of [M-PFB-2TMSOH]- by NICI/GC/MS/MS analysis, which was the product ion of [M-PFB]-. The detection limit for the quantification of LTB4 in human plasma was 10 pg ml-1, sufficiently sensitive to determine the concentrations of endogenous LTB4 in human plasma. The plasma level of LTB4 measured in healthy male volunteers was 33.85 +/- 33.91 pg ml-1 (mean +/- S.D. in six volunteers). The technique of MS/MS used in this method offers much greater sensitivity and selectivity than single-stage mass spectrometry. The developed method showed good reproducibility with a simple and rapid extraction procedure, and would be useful for examining the relationship between various disease states and the levels of LTB4 in biological fluids.

[Research and development of ozagrel, a highly selective inhibitor of TXA2 synthase].

Highly selective inhibitors of thromboxane (TX) A2 synthase were noted as a therapeutic agent for ischemic heart diseases, thromboembolic disorders, cerebral circulatory disorders, and asthma. The 1-substituted imidazoles and beta-substituted pyridines showed high inhibitory potency on TXA2 synthase. The structure-activity relationships of the imidazole and pyridine derivatives as inhibitors of TXA2 synthase were investigated. Introduction of various substituents into the carboxy-bearing side chain of 1-(7-carboxyheptyl) imidazole and beta-(7-carboxyheptyl) pyridine was found to increase the inhibitory potency. The length of the side chains with the phenylene group was optimum in the region of 8.5 to 10 A for the inhibitory potency on TXA2 synthase. Among the tested imidazole and pyridine derivatives, (E)-4-(1-imidazolylmethyl)cinnamic acid (44) and (E)-3-[4-(3-pyridylmethyl)phenyl]-2-methylacrylic acid (56) showed the highest potency (IC50 = 1.1 x 10(-8) and 3 x 10(-9) M). The inhibition by these derivatives was highly selective for TXA2 synthase, since other enzymes which are involved in the arachidonic acid cascade, such as fatty acid cyclooxygenase, 5-lipoxygenase, prostacyclin (PGI2) synthase, and PGE2 isomerase were not affected. On the basis of the results obtained from the pharmacological, physicochemical and toxicological studies on the two compounds (44 and 56), (E)-4-(1-imidazolylmethyl) cinnamic acid (44; OKY-046, ozagrel) was selected as the best compound of highly selective inhibitors of TXA2 synthase. The pharmacological properties of ozagrel are as follows. The inhibition of TXA2 synthase by ozagrel was more effective on human and rabbit enzymes than those of other species. Ozagrel increased 6-keto-PGF1 alpha, one of stable metabolites of PGI2, in various isolated cells and tissues perhaps via accumulated PG endoperoxides resulted by the inhibition of TXA2 synthase. Such an increase in PGI2 production by ozagrel was also observed in various experimental animals. We obtained the suggestion that, by the reduction of TXA2 production and increment of PGI2 production, ozagrel inhibits the spasms of basilar artery and the decreases in regional cerebral blood flow in dogs which received autologous blood into cisterna magna, and inhibits the decreases in motor function and regional cerebral blood flow, and the formation of infarcted area in the animals of cerebral ischemic treatment. It was also suggested that ozagrel inhibits leukotriene-, platelet-activating factor-, and antigen-induced bronchoconstriction in guinea-pigs and inhibits the induction of airway hyperresponsiveness by various stimuli in several species of animals by both mechanisms. The summarized results of ADME, toxicological, and clinical studies were also described.

Pharmacological studies on the TXA2 synthetase inhibitor (E)-3-[p-(1H-imidazol-1-ylmethyl)phenyl]-2-propenoic acid (OKY-046).

The effects of (E)-3-[p-(1H-imidazol-1-ylmethyl)phenyl]-2-propenoic acid (OKY-046) on thromboxane A2 (TXA2) synthetase in vitro and on experimental animal models of sudden death and cerebral infarction were studied. IC50 values of OKY-046 for the TXA2 synthetase of human, rabbit, dog and guinea pig washed platelets were 0.004, 0.004, 0.26 and 2.4 microM, respectively. OKY-046 at concentrations up to 1 mM, however, did not inhibit prostacyclin (PGI2) synthetase from bovine aorta microsomes or cyclooxygenase and PGE2 isomerase from sheep seminal vesicle microsomes. Similarly, platelet 12-lipoxygenase was not affected by OKY-046. Evidence for a re-direction of arachidonate metabolism from thromboxane synthesis toward PGI2 synthesis was obtained using rat peritoneal cells. Namely, OKY-046 increased PGI2 production accompanied by an inhibition of TXA2 production at a concentration of more than 1 microM. OKY-046 at a dose of 0.1 mg/kg (i.v.) in dogs inhibited the aortic and mesenteric arterial contraction of rabbit induced by the addition of arachidonate to extracorporated blood of the dogs. OKY-046 at a dose of 0.3 mg/kg (i.v.) prevented the arachidonate-induced sudden death and also decreased the incidence of cerebral infarction induced by injection of arachidonate into the internal carotid artery in rabbits. Aspirin also decreased the incidence of cerebral infarction at a dose of 30 mg/kg (i.v.). These results suggest that OKY-046 may be valuable for the treatment of cerebrovascular and cardiovascular diseases associated with vasoconstriction and thrombosis due to TXA2.

Beneficial effect of OKY-046, a selective thromboxane A2 synthetase inhibitor, on experimental cerebral vasospasm.

Effects of OKY-046, a selective inhibitor of thromboxane (TX)A2 synthetase and a platelet aggregation inhibitor, on in vitro and in vivo models of cerebral vasospasm were studied. The contraction of the isolated rabbit basilar artery by an exposure to 1.0 ml of whole rabbit blood plus 0.05 or 0.1 units/ml of thrombin was diminished by the treatment with 10(-4) M of OKY-046 and/or 10(-6) M of cinanserin. When the whole blood of rabbits treated intravenously with 1 mg/kg/min of OKY-046 was used, the contraction of the basilar artery was decreased to about half of the control contraction. Angiographically recognized cerebral vasospasm in vivo, by a transorbital injection of 5.0 to 7.0 ml of autologous arterial blood into the cisterna magna of dogs, was suppressed by 0.05 and 0.5 microgram of OKY-046. Moreover, the decrease in the regional cerebral blood flow in autologous blood infused-dogs was inhibited by 0.5 microgram of OKY-046. The increase in TXB2 in the cerebrospinal fluid of dogs was significantly inhibited, and the level of 6-keto-PGF1 alpha was slightly increased by the treatment of OKY-046. The ratio of 6-keto-PGF1 alpha/TXB2 was increased from 1.5 to 5.2 in OKY-046-treated dogs. No effect on the basal tone and response to vasoactive agonists such as norepinephrine, KCl and PGE1 was observed in the isolated spiral thoracic aorta of guinea pigs or rabbits. Taken together with our previous findings, we conclude that the inhibition of cerebral vasospasm in the in vitro and in vivo models by the treatment of OKY-046 might be due to an inhibition of platelet aggregation, an inhibition of TXA2 generation and an increase in the ratio of PGl2/TXA2.

Intravenous infusion of a selective inhibitor of thromboxane A2 synthetase in man: influence on thromboxane B2 and 6-keto-prostaglandin F1 alpha levels and platelet aggregation.

The effect of the selective thromboxane A2 synthetase inhibitor OKY-1581, a pyridine derivative [sodium (E)-3-(4-(3-pyridylmethyl)phenyl)-2-methyl-2-propenoate], on thromboxane B2 and 6-keto-prostaglandin F1 alpha levels and platelet aggregation was studied in human volunteers. To clarify its effectiveness as an enzyme inhibitor, OKY-1581, at doses of 17, 83, 167, 417, 833, and 1667 micrograms/kg (n = 5 for each group), was injected intravenously, or was infused (10 micrograms/kg/min; n = 5) over 3 hr on 3 successive days. OKY-1580 (OKY-1581 free acid) was rapidly converted to its main beta-oxidized product, OKY-1565, and its reduced form, OKY-1558. During the study, plasma thromboxane B2 levels, inhibition of thromboxane B2 production in serum, and inhibition of rabbit platelet thromboxane A2 synthetase were monitored continuously. Twenty-five minutes after the injection of the above doses, plasma thromboxane B2 levels decreased by 4 +/- 7%, 40 +/- 14%, 57 +/- 7%, 68 +/- 6%, 93 +/- 5%, and 96 +/- 5% (mean +/- SD), respectively. Thromboxane B2 production in serum was decreased by 2 +/- 8%, 70 +/- 10%, 75 +/- 8%, 81 +/- 10%, and 96 +/- 8%, respectively, and rabbit platelet thromboxane A2 synthetase by 2 +/- 7%, 52 +/- 8%, 79 +/- 10%, 80 +/- 9%, 96 +/- 8%, and 95 +/- 7%. These parameters returned to the control levels 24 hr after the injection.(ABSTRACT TRUNCATED AT 250 WORDS)