Urinary thromboxane A2/prostacyclin balance reflects the pathological state of a diabetic

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) were measured in diabetics to elucidate the relation between the thromboxane A2/prostacyclin (TX/PGI) balance and pathological states of diabetes mellitus. 11-Dehydro-TXB2 and 2,3-dinor-6-keto-PGF1alpha were derivatized to methyl ester-propylamide-dimethylisopropylsilyl ether and methyl ester-methoxime-dimethylisopropylsilyl ether derivatives, respectively, and applied to a gas chromatography/selected ion monitoring. The TX/PGI ratios of diabetics were higher than those of healthy volunteers, suggesting the hypercoagulative states of this disease. The ratios showed positive correlations with the levels of blood glucose. The levels of hemoglobin A1c and triglyceride were correlated weakly with the ratio. Some of the patients who had relatively low levels of blood glucose also showed high TX/PGI ratios. Furthermore, the ratio increased in the order of the groups 1, 2, and 3; group 1 contained patients who did not take medicine for diabetes, group 2 contained those who took oral hypoglycemic agents, and group 3 contained those who received insulin therapy. These observations indicate that the TX/PGI ratio reflects the pathological conditions of diabetes and is a useful marker, having few different features from other markers that are presently used.

Monitoring of the thromboxane A2/prostacyclin ratio in the urine of patients with retinal vascular occlusion through the low-dose-aspirin therapy using the gas chromatography/selected ion monitoring method

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.

Microdetermination of prostaglandin E2 in joint fluid in rheumatoid arthritis patients using gas chromatography/selected ion monitoring

We devised an effective purification for the microdetermination of prostaglandin E2 (PGE2) in human joint fluid using gas chromatography/selected ion monitoring and determined PGE2 in the joint fluid in rheumatoid arthritis (RA) patients using this method. The methyl estermethoxime-tert-butyldimethylsilyl ether derivative was prepared, then gas chromatography/selected ion monitoring was carried out by monitoring the ion at m/z 566.4 for PGE2 and at m/z 570.4 for the internal standard (PGE2-d4). A good linear response over the range of 10 pg to 50 ng was demonstrated. We detected PGE2 to a level of about 46 pg/ml in the joint fluid of RA patients. The level of PGE2 in RA patients was significantly higher than that in osteoarthritis patients used as controls. Moreover, we measured inflammatory cytokine (IL-1beta, TNFalpha, IL-6 receptor) levels in joint fluid by using enzyme-linked immunosorbent assay. A relationships between the PGE2 level in joint fluid and these cytokines or biochemical data as the indicator of RA disease was not observed. We found that the PGE2 level in each patient was influenced by therapeutic drugs. The PGE2 level in RA patients with non-steroidal anti-inflammatory drugs was lower than with steroids.

Microdetermination of the 6,15-diketo-13,14-dihydroprostaglandin F1alpha in human plasma using gas chromatography/selected ion monitoring with [18O]6,15-diketo-13,14-dihydro-prostaglandin F1alpha as an internal standard

We devised a simple and effective purification method for the microdetermination of 6,15-diketo-13,14-dihydro-prostaglandin F1alpha (DK), a metabolite of prostacyclin (PGI2). [18O]DK was synthesized from the repeated base-catalyzed hydrolysis of methyl ester derivatives in [18O] water to obtain an internal standard for the gas chromatography/selected ion monitoring (GC/SIM) of DK. The methyl ester-methoxime-tert-butyldimethylsilyl ether derivative was prepared, then gas chromatography/selected ion monitoring was carried out by monitoring the ion at m/z 613.4 for DK and at m/z 617.4 for an internal standard. A good linear response over the range of 10 pg to 10 ng was demonstrated. We detected DK to a level of about 297.8 pg/ml in human plasma. This method can be used to determine DK in biological samples.

Effects of long-term supplementation of eicosapentanoic and docosahexanoic acid on the 2-, 3-series prostacyclin production by endothelial cells

We studied the effects of polyunsaturated fatty, acids such as arachidonic acid [20:4 (n-6)], eicosapentanoic acid [EPA, 20:5 (n-3)], and docosahexanoic acid [DHA, 22:6 (n-3)] on the changes of lipid profiles and prostacyclin production by cultured bovine aortic endothelial cells. The amounts of 6-keto-prostaglandin F1alpha(6-keto-PGF1alpha) and delta17-6-keto-PGF1alpha, non-enzymatic metabolites of prostacyclin (PGI2 and PGI3) in culture medium were measured by gas chromatography/selected ion monitoring. Endothelial cells were supplemented for five passages with arachidonic acid, EPA, or DHA, and the fatty acids of cell lipids and prostacyclin production in cultured medium were quantified. From the fatty acid analysis, the amounts of docosapentaenoic acid [22:5 (n-3)] were significantly increased in EPA-grown cells. In DHA-grown cells, the amounts of EPA were slightly increased compared to control cells. These cells produced similar amounts of PGI2 as the controls, but larger amounts of PGI3 under basal conditions. These findings suggest that EPA, docosapentaenoic acid, and DHA are interconverted to each other, and anti-aggregatory effects of EPA or DHA may be partially due to the stimulation of prostacyclin formation in endothelial cells.

Determination of leukotriene E4 in human urine using liquid chromatography-tandem mass spectrometry

A liquid chromatographic-tandem mass spectrometric (LC-MS-MS) method was developed for the quantitation of urinary leukotriene E4 (LTE4). LTE4 and its internal standard were extracted by solid-phase extraction and analysed using LC-MS-MS in the selected reaction monitoring (SRM) mode. A good linear response over the range of 10 pg to 10 ng was demonstrated. The accuracy of added LTE4 ranged from 97.0% to 108.0% with a mean and SD of 100.6+/-2.4%. We detected LTE4 (63.1+/-18.7 pg/mg creatinine, n=10) in healthy human urine. This method can be used to determine LTE4 in biological samples.

Analysis of urinary 11-dehydrothromboxane B2 in patients with occluded retinal vein using GC/SIM

We describe variations of 11-dehydrothromboxane B2(11-dehydro-TXB2) levels in human urine samples. Retinal vein occlusion (RVO) is a thrombotic disease in which the retinal vein is blocked by blood aggregations. We considered the possibility that 11-dehydro-TXB2 plays an important role in the formation of RVO. Thus, we determined the 11-dehydro-TXB2 levels in patients with RVO using gas chromatography/selected ion monitoring (GC/SIM) and compared them with those of healthy volunteers. The thromboxane levels in patients with RVO, who did not also have diabetes, were significantly higher than those in healthy volunteers. One cause of RVO may be the variation of thromboxane production. Furthermore, this GC/SIM method can be applied to the prevention and treatment of not only RVO, but also of general thrombosis.

Alteration of DNA methylation levels in MRL lupus mice

Recent reports suggest that DNA methylation is involved in the cause of autoimmune disease. We investigated the alteration of DNA methylation levels in lupus strains of mice, MRL/lpr as a model, which develop an age-dependent lymphadenopathy and autoimmune disease. DNA methylation levels of thymus and axillary lymph nodes in 20-week-old MRL/lpr mice, which are in an autoimmune disease state, were lower than those of 4-week-old MRL/lpr mice with no symptoms as yet. No significant changes were observed in MRL/+ strain mice, which seemed normal at least 20 weeks, while DNA methylation levels in the spleen of both strains of mice increased significantly from the age of 4 to 20 weeks. However, no significant changes of DNA methylation levels in peripheral blood were observed with ageing in MRL strains. Moreover, we clarified that administration of 5-azacytidine had a strong effect on longer survival of MRL/lpr mice and reduced DNA methylation levels in the axillary lymph nodes and spleen. The possible relevance of DNA methylation levels to the progression of autoimmune disease is discussed.

Effects of eicosapentaenoic acid (EPA) on prostacyclin production in diabetics: GC/MS analysis of PGI2 and PGI3 levels

The enzymatic metabolites, 6-keto-PGF1 alpha and delta 17-6-keto-PGF1 alpha, were measured by gas chromatography/high resolution-selected ion monitoring (GC/HR-SIM) as markers of prostaglandin I2 (PGI2) and prostacyclin (PGI3) production in human sera. Eicosapentaenoic acid (EPA) ethyl ester (1.8 g/day) was administered to 12 noninsulin-dependent diabetes mellitus (NIDDM) patients for 2 weeks. Forty patients with similar NIDDM were followed as a control group. PGI3 production in sera was significantly increased in the EPA intake group in comparison with the control group. These findings suggest that EPA intake prevents complications of diabetes mellitus, such as microangiopathy and vaso-occlusive diseases.

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.

4 Pro-R hydrogen of NADPH was abstracted for enzymatic hydride transfer by N-ethylmaleimide-reductase of Yarrowia lipolytica

We studied the steric course of the reaction catalyzed by the N-ethylmaleimide (NEM) reductase of Yarrowia (Candida) lipolytica (Y. lipolytica), using 4R-[4-2H1]NADPH and 4S-[4-2H1]NADPH as cofactors and N-ethylcitraconimide as substrate. Active substrates and inhibitors of NEM reductase and its subcellular distribution were also investigated to clarify the biochemical properties of this enzyme. NEM reductase catalyzes the reduction of N-ethylmaleimide to N-ethylsuccinimide with NAD(P)H as the cofactor. Several maleimide and cyclopentenone derivatives tested were also active substrates for NEM reductase of Y. lipolytica. Some pyrazolone derivatives, particularly 1-phenyl-5-pyrazolone, were found to be effective inhibitors of NEM reductase. Subcellular localization of NEM reductase was carried out using protoplast formation and differential centrifugation. Ninety-eight percent of the NEM reductase activity was recovered in the cytosolic fraction, indicating that NEM reductase in Y. lipolytica was the cytosolic enzyme. We also determined the stereochemical specificity of the reduction of N-ethylcitraconimide by NEM reductase in Y. lipolytica, showing that 4 Pro-R hydrogen of NADPH was abstracted for enzymatic hydride transfer by NEM reductase, and two hydrogen atoms from NADPH and H2O added to opposite faces of the double bond of N-ethylcitraconimide.

The effects of unsaturated fatty acids, oxidizing agents and Michael reaction acceptors on the induction of N-ethylmaleimide reductase in Escherichia coli: possible application for drug design of chemoprotectors

Menadione and dimethyl maleate, Michael reaction acceptors, induced N-ethylmaleimide (NEM) reductase activity in Escherichia coli strain DH5a. Linoleic acid also induced NEM reductase activity, but oleic acid, which is less susceptible to lipid peroxidation than linoleic acid, did not induce NEM reductase activity. In addition, NEM reductase activity was induced by menadione and linoleic acid also in strain DH5, Y1088 and Y1090. Linoleic acid is not a Michael reaction acceptor, but is known to produce Michael reaction acceptors such as alkenals and 4-hydroxyalkenals as a result of free-radical-initiated lipid peroxidation. Thus, our findings suggested that lipid peroxidation was involved in the induction of NEM reductase by linoleic acid. The electrophilic property of Michael reaction acceptors provides the signal for induction of phase II enzymes such as glutathione S-transferase and quinone reductase in mammals. The inducer potency of phase II enzymes has been used to design chemoprotective drugs. Therefore, the inducible nature of this enzyme will serve not only for the elucidation of its physiological function, but also for the evaluation of chemoprotective drugs.

Phenobarbital molecularly imprinted polymer selectively binds phenobarbital

Molecularly imprinted polymer (MIP) was prepared against phenobarbital using methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross linking monomer. We analyzed the recognition properties of the phenobarbital MIP. In some organic solvents, imprinted polymer showed selective binding to phenobarbital. Two dissociation constants of binding were calculated by Scatchard plot analyses; Kd values were 1.8, 121.7 microM, and the number of binding sites was 8.3, 92.3 mumol/g MIP in toluene-heptane-acetic acid (25 : 75 : 1, v/v), respectively. The relationship between the binding affinity to phenobarbital MIP and the polarity of the solvent system, as well as the structure of the template molecule is also discussed.

[Radiotherapy of esophageal cancer: clinical usefulness of new grouping]

A total of 188 cases of nonresected esophageal cancer were categorized into the following groups based on T category. (1987 UICC) and radiological classification (Japanese Society of Esophageal Diseases); Group 1: superficial or early (T2 or less) tumorous type; Group 2: advanced tumorous type, early serrated or early spiral type; Group 3: others. The response to radiotherapy was significantly related to the group. According to the proportional hazard model, the important factors predicting long-term survival were T category, radiotherapy response at the end of treatment, and group. There was a tendency to obtain better local control in group 1 patients than in group 2 patients, but cause-specific survival was the same for both groups (mainly the appearance of distant metastases). Local control was poor in group 3. If the tumor response at 40Gy was excellent in group 2 patients, the main cause of death was distant metastases, much the same as in group 1 patients. However, if response at 40Gy was not excellent, the main cause of death was local failure even though final tumor response was excellent. It seemed that therapy that may improve local control is valuable for group 3 patient, and for group 2 patients whose tumor response at 40Gy was not excellent.

Effects of haloperidol and cocaine pretreatments on brain distribution and kinetics of [11C]methamphetamine in methamphetamine sensitized dog: application of PET to drug pharmacokinetic study

Repeated administration of methamphetamine (MAP) causes behavioral sensitization in animals. We previously reported that the maximum accumulation level of [11C]MAP in the MAP-sensitized dog brain was 1.4 times higher than that in the control. In behavioral studies, haloperidol (a dopamine D2 receptor antagonist) prevents MAP-induced behavioral sensitization, and cocaine (a dopamine reuptake blocker) has the cross-behavioral sensitization with MAP. In the present study, to elucidate the relation between the MAP-induced behavioral sensitization and the pharmacokinetics of MAP, we investigated the effects of haloperidol and cocaine pretreatments on brain regional distribution and kinetics of [11C]MAP using positron emission tomography (PET). A significant increase of [11C]MAP uptake into the sensitized dog brain was prevented by haloperidol and cocaine pretreatments. These pharmacokinetic changes were not due to the changes in the rate of MAP metabolism. These results suggest haloperidol and cocaine can change the cerebral pharmacokinetic profile of MAP in the behavioral-sensitized dog. The variations of MAP-accumulation may affect the development or expression of MAP-induced behavioral sensitization.

Molecular cloning of the nemA gene encoding N-ethylmaleimide reductase from Escherichia coli

Using the gene mapping membrane technique, we identified a gene (nemA) that encodes N-ethylmaleimide reductase in Escherichia coli. The open reading frame encodes a polypeptide of 365 amino acids with a molecular mass of 39,514 Da. The deduced amino acid sequence showed a high degree of homology (87% identical) with the pentaerythritol tetranitrate reductase of Enterobacter cloacae and the morphinone reductase of Pseudomonas putida (52% identical).

Preparation of a monoclonal antibody specific for 5-methyl-2'-deoxycytidine and its application for the detection of DNA methylation levels in human peripheral blood cells

A monoclonal antibody specific for a modified nucleoside, 5-methyl-2'-deoxycytidine (m5dCyd), was prepared using 5-methylcytidine (m5Cyd)-keyhole limpet haemocyanin (KLH) conjugate, and was characterized. Termed FMC9, the antibody reacts with m5dCyd and slightly with m5Cyd and 5-methylcytosine (m5Cyt) but not with other nucleosides tested in this investigation. FMC-9 was used in an enzyme-linked immunosorbent assay (ELISA) system for the quantitation of m5dCyd levels. Sensitivity was in the picomole range. Methylation levels in peripheral blood cells of healthy donors were determined by inhibition ELISA. The percentage of m5dCyd in peripheral blood cells of 10 healthy donors was 5.08 +/- 0.50%. These results suggest that the inhibition ELISA using FMC9 is useful to monitor m5dCyd levels in the peripheral blood cells.

Positron emission tomography study of the alterations in brain distribution of [11C]methamphetamine in methamphetamine-sensitized dog

We newly prepared a MAP-sensitized dog by repeated MAP treatment and studied the brain distribution of [11C]MAP in the normal and the MAP-sensitized dog using PET. The maximal level of accumulation of [11C]MAP in the sensitized dog brain was 1.4 times higher than that in the control. No difference was found in the metabolism of MAP between the two conditions. The significant increase of [11C]MAP in the MAP-sensitized brain indicates that subchronic MAP administration causes some functional change in the uptake site of MAP. The pharmacokinetic change may, in part, account for behavioral sensitization.

Analysis of the thromboxane/prostacyclin balance in human urine by gas chromatography/selected ion monitoring: abnormalities in diabetics

We microanalyzed 2,3-dinor-6-keto-prostaglandin F1 alpha (2,3-dinor-6-keto-PGF1 alpha 1) and 11-dehydrothromboxane B2 (11-dehydro-TXB2, 2) in human urine. Samples containing a [2H4]-analogue as an internal standard were extracted by chromatography using Sep Pak tC18 and silica gel. The compounds were then analysed by means of the lactone ring opening reaction and dimethylisopropylsilylation. The conversion of 1 to 1-methyl ester (ME)-propylamide (PA)-9, 12, 15-dimethylisopropylsilyl (DMIPS) ether derivative and of 2 to 1-ME-6-methoxime (MO)-9, 12, 15-tris-DMIPS ether derivative was followed by gas chromatography/selected ion monitoring (GC/SIM). Interfering substances from the urine matrix were eliminated during GC/SIM analysis using a DB-5 column. We were able to detect 1 (222-1031 pg/mg creatinine) and 2 (18-155 pg/mg creatinine) in human urine. Furthermore, the thromboxane/prostacyclin (IX/PGI) ratio in the urine of diabetics was higher than that of healthy volunteers. This method can be used to determine the TX/PGI balance in human urine.

Effects of clofibrate on flow cytometric populations in rat liver

A flow cytometric study was performed on the liver of normal and clofibrate-treated rats. The flow cytometric patterns of these fractions showed three distinct populations (R1, R2 and R3). The R3 region was remarkably increased in the clofibrate-treated nuclear fraction, and was applied to sucrose linear density gradient centrifugation. Mt1, Mt2, Mt3 and Mt4 fractions were isolated and reacted with rhodamine-123. An essential enzyme for beta-oxidation, delta 3, delta 2-enoyl-CoA isomerase, was mainly expressed in Mt1 of the control-nuclear fraction, but not in Mt1, Mt2 and Mt4 in the clofibrate-treated nuclear fraction. These results suggest that clofibrate affects the flow cytometrical population of the mitochondria and changes the expression level of beta-oxidation enzyme(s) of the mitochondria in rat liver.

Determination of Aconitum alkaloids in the tubers of Aconitum japonicum using gas chromatography/selected ion monitoring

A rapid, specific and precise method using GC/SIM was applied to separate and quantify Aconitum alkaloids in Aconitum tubers. The TMS derivatives of each alkaloid produced a well defined peak on selected ion recording (SIR). Good linear response over the range of 100 pg - 7.5 ng was demonstrated for each alkaloid. Furthermore, we investigated the changes in the contents of Aconitum alkaloids, i.e., hypaconitine, mesaconitine, aconitine, and jesaconitine, in Aconitum tubers paying special attention to the harvesting season. Mesaconitine had the highest value in all seasons. Mesaconitine and aconitine showed the highest value in the samples harvested in May 1991 while hypaconitine had the highest value among those harvested in December 1990. As to the total amount of the alkaloids, the highest value, 4190 microg/g, and the lowest value, 1881 microg/g, were observed in the samples harvested in May and September, respectively. GC/SIM was very useful for the determination of Aconitum alkaloids in the tubers.

Effect of diabetic sera on the conversion of eicosapentaenoic acid (EPA) to prostaglandin I3 by cultured bovine aortic endothelial cells

The effects of sera from diabetic patients and healthy donors on the synthesis of prostaglandin I2 (PGI2) and PGI3 in vitro were studied in confluent bovine aortic endothelial cells cultured with EPA. The products 6-keto-PGF1 alpha and delta 17-6-keto-PGF1 alpha were measured by GC/SIM as markers of PGI2 and PGI3 formation in growth medium after 60 min of incubation. PGI2 and PGI3 synthesis with 10% diabetic sera were less than with sera from healthy donors (p < 0.05). However, the total prostacyclin production (PGI2 and PGI3) in the cell cultures incubated with 10 microM EPA and 10% diabetic sera approximated that of the cultures incubated with the sera of healthy donors without EPA. These results suggest that the diabetic sera inhibits PGI2 and PGI3 synthesis in the cultured endothelial cells, and that EPA intake may reduce the complications of diabetes mellitus, such as microangiopathy and vaso-occlusive diseases, and enhances the production of PGI3 which seems to exert a strong anti-aggregatory effect.

Positron emission tomography (PET) study of the alterations in brain distribution of [11C]methamphetamine in methamphetamine sensitized dog

[11C]Methamphetamine ([11C]MAP) was synthesized by an automated on-line [11C]methylation system for positron emission tomography (PET) study. We newly produced a MAP sensitized dog by repeated MAP treatment and studied the brain distribution of [11C]MAP in the normal and the MAP sensitized dog. The maximal level of accumulation of [11C]MAP in the sensitized dog brain was 1.4 times higher than that in the control. No difference was found in the metabolism of MAP between the two conditions. The significant increase of [11C]MAP in the MAP sensitized brain indicates that subchronic MAP administration causes some functional change in uptake site of MAP.

Microdetermination of the prostaglandin B1 in human plasma by gas chromatography/selected ion monitoring using [18O]prostaglandin B1 as an internal standard

We devised a simple and effective purification for the microdetermination of prostaglandin B1 (PGB1), a metabolite of PGE1. [18O]PGB1 was synthesized by the repeated base-catalyzed hydrolysis of methyl ester derivatives in H(2)18O, to obtain an internal standard for the gas chromatography/selected ion monitoring (GC/SIM) of PGB1. The methyl ester-methoxime-dimethylisopropylsilyl ether derivative was prepared, then GC/SIM was carried out by monitoring the ion at m/z 448.3 for PGB1 and that at m/z 452.3 for internal standard. A good linear response over the range of 10 pg to 100 ng was demonstrated. We detected PGB1 to a level of about 40 pg/mL in human plasma. This method can be used to determine PGB1 in biological samples.

Identification of 11-dehydro-2,3-dinorthromboxane B3 in human urine based on the mass spectral properties of 11-dehydrothromboxane B3 and related compounds

11-Dehydro-2,3-dinorthromboxane B3 (an enzymatic metabolite of TXB3) was identified. Urine from a healthy male adult who had received daily administration of 1.8 g (0.6 g three times) of eicosapentaenoic acid (EPA) ethyl ester was collected. A urine sample was extracted with an affinity column of anti-11-dehydro-TXB2 monoclonal antibody. Conversion of 11-dehydro-2,3-dinor-TXB3 in the urine extract into the methyl ester (ME)-11-n-propylamide (PA)-9, 12, 15-dimethylisopropylsilyl (DMIPS) ether derivative was followed by gas chromatography with selected-ion monitoring (GC/SIM) (resolution: 8000) and GC/mass spectrometry (MS). High-resolution SIM result revealed that a major component corresponded to the [M - C3H7]+ (m/z 668.4198) ion, which may be specific for the structural integrity by analogy with the corresponding 11-dehydro-TXB3 derivative. Conventional GC/MS analysis confirmed that the peak of the interest was the title compound. The mass spectrum of the 11-dehydro-2,3-dinor-TXB3 ME-PA-DMIPS ether derivative was dominated by the ions of [M - CH3]+ (m/z 696) and [M - C3H7]+ (m/z 668, base peak) and ions containing a protected 11-carboxylic acid moiety together with the unidentified additional ions which were considered to derive from urinary endogenous substances. However, the quality was sufficient for use of mass spectral identification of 11-dehydro-2,3-dinor-TXB3, the beta-oxidation product of 11-dehydro-TXB3. Characteristic fragment ions of [M - C5H9-(dimethylisopropylsilanol)n]+ (m/z 524 and 406) yielding information about the position of the incorporated double bond were prominent, the same as the corresponding ions found in the mass spectrum of the 11-dehydro-TXB3 derivative. Consequently, the fragmentation products were closely related to those of the 11-dehydro-TXB3 derivative, except for an obvious shift produced by the lack of C-2/C-3 hydrocarbon units. The results demonstrate the endogenous formation of TXA3 in humans after administration of EPA ethyl ester and excretion of 11-dehydro-2,3-dinor-TXB3 into urine as one of the enzymatic metabolites of TXB3, together with the previously reported 11-dehydro-TXB3.