Search

Mass spectrometry (MS) is increasingly used in clinical medicine in Japan. In contrast to the successful application of MS in clinical microbiology, the adoption of MS-based assays for routine testing in clinical chemistry is very slow. In order to promote the significant benefits that MS platforms bring to laboratory medicine and patient care, the Japanese Society for Biomedical Mass Spectrometry (JSBMS) initiated a medical mass spectrometrist (MMS) certification program in 2013. As of Dec 2018, 308 persons from various medical specialties have been certified. We believe that they will play significant roles for expanding routine clinical MS usage in Japan.

The use of antipsychotic drugs is limited by their tendency to produce extrapyramidal movement disorders such as tardive dyskinesia and parkinsonism. In previous reports it was speculated that extrapyramidal side effects associated with the butyrophenone neuroleptic agent haloperidol (HP) could be caused in part by the neurotoxic effect of its pyridinium metabolite (HPP(+)). Although both HPP(+) and HP have been shown to induce neurotoxic effects such as loss of cell membrane integrity, no information exists about the difference in the neurotoxic potency, especially in the potency to induce plasma membrane damage, between these two agents. In the present study, we compared the potency of the interaction of HPP(+) and HP with the plasma membrane integrity in the rat brain. Membrane permeabilization (assessed as [(18)F]2-fluoro-2-deoxy-d-glucose-6-phosphate release from brain slices) and fluidization (assessed as the reduction in the plasma membrane anisotropy of 1,6-diphenyl 1,3,5-hexatriene) were induced by HPP(+) loading (ator=100 microM andor=10 microM, respectively), while comparable changes were induced only at a higher concentration of HP (=1 mM). These results suggest that HPP(+) has a higher potency to induce plasma membrane damage than HP, and these actions of HPP(+) may partly underlie the pathogenesis of HP-induced extrapyramidal side effects.

In this study, we investigated the effect of vesicular zinc on ischemic neuronal injury. In cultured neurons, addition of a low concentration (under 100 µM) of zinc inhibited both glutamate-induced calcium influx and neuronal death. In contrast, a higher concentration (over 150 µM) of zinc decreased neuronal viability, although calcium influx was inhibited. These results indicate that zinc exhibits biphasic effects depending on its concentration. Furthermore, in cultured neurons, co-addition of glutamate and CaEDTA, which binds extra-cellular zinc, increased glutamate-induced calcium influx and aggravated the neurotoxicity of glutamate. In a rat transient middle cerebral artery occlusion (MCAO) model, the infarction volume, which is related to the neurotoxicity of glutamate, increased rapidly on the intracerebral ventricular injection of CaEDTA 30 min prior to occlusion. These results suggest that zinc released from synaptic vesicles may provide a protective effect against ischemic neuronal injury. Keywords:: zinc, ischemia, glutamate, middle cerebral artery occlusion, CaEDTA

The inhibitory effects of quinolone antimicrobial agents and nonsteroidal anti-inflammatory drugs on purified mouse liver mitochondrial medium chain acyl-CoA synthetase catalyzing the first reaction of glycine conjugation were examined, using hexanoic acid as a substrate. Enoxacin, ofloxacin, nalidixic acid, diflunisal, salicylic acid, 2-hydroxynaphthoic acid, and 2-hydroxydodecanoic acid, which do not act as substrates, were potent inhibitors. Diflunisal, nalidixic acid, salicylic acid, 2-hydroxynaphthoic acid, and 2-hydroxydodecanoic acid inhibited competitively this medium chain acyl-CoA synthetase with K(i) values of 0.6, 12.4, 19.6, 13.4, and 15.0 microM, respectively. Enoxacin and ofloxacin inhibited this medium chain acyl-CoA synthetase in a mixed-type manner with K(i) values of 23.7 and 38.2 microM, respectively. Felbinac, which is a substrate, inhibited the activity of this medium chain acyl-CoA synthetase for hexanoic acid (IC50 = 25 microM). The concomitant presence of enoxacin and felbinac strongly inhibited this medium chain acyl-CoA synthetase. These findings indicate that medium chain acyl-CoA synthetases may be influenced by quinolone antimicrobial and nonsteroidal anti-inflammatory drugs.

The relative importance of the liver and kidney for glycine conjugation of ortho-substituted benzoic acids was investigated. Glycine conjugation of ortho-substituted benzoic acids was investigated in mouse liver and kidney mitochondria. The extent of glycine conjugation of benzoic acids with the halogen group decreased in the order F > Cl > Br > I. The conjugation of salicylic acid with glycine took place in only the kidney. 2-Methoxybenzoic acid exhibited no activity in the liver and kidney. The difference in glycine conjugation of ortho-substituted benzoic acids was observed between liver and kidney. The kidney was more active in glycine conjugation of ortho-substituted acids than the liver. In addition, the relationship between glycine conjugation and the chemical structure of ortho-substituted acids was examined in the liver and kidney. The size of the substituent had a far greater influence over glycine conjugation in the liver and kidney. Glycine conjugation was also dependent on the substituent electronegativity. It may be important that the substrates undergoing glycine conjugation contain a flat region coplanar to the carboxylate group.

Glycine conjugation of a series of benzoic acid derivatives was investigated in mouse kidney mitochondria. The chlorine and methyl substitutions in the para- and meta-positions of the benzene ring yielded an increase in glycine conjugation. The acids with a methoxy group showed a low degree of glycine conjugation. In addition, the acids with nitro or amino groups were conjugated to a slight extent with glycine. The in vitro conjugation of salicylic acid with glycine occurred not in liver but in kidney. The specificity of the renal medium chain acyl-CoA synthetase catalyzing the first reaction of glycine conjugation was also examined. The enzyme accepted not only medium chain fatty acids but also aromatic and arylacetic acids. The highest activity was shown with hexanoic acid. High activities were observed for benzoic acid derivatives with alkyl and alkoxyl groups in the para- and meta-positions of the benzene ring. An ortho-substituted acid exhibited no activity. In addition, the enzyme was less active with valproic acid, tranexamic acid, indomethacin and ketoprofen. The enzyme was inhibited by diflunisal, 2-hydroxydodecanoic acid and salicylic acid, which did not act as substrates. There was a poor correlation between the activity of the medium chain acyl-CoA synthetase and glycine conjugation of eleven substituted benzoic acids. These findings suggest that the present medium chain acyl-CoA synthetase is involved in glycine conjugation of the substituted acids in mouse kidney mitochondria, but there may be a larger contribution of another isoenzyme.

To investigate the relationship between CYP2D6 genotypes (reported to be associated with the susceptibilities to Parkinson’s disease and multisystem atrophy) and the possible susceptibility to neuroleptic malignant syndrome (NMS) and subacute myelo-optico-neuropathy (SMON), we analyzed the CYP2D6 gene by polymerase chain reaction and restriction fragment length polymorphism in Japanese schizophrenia patients with a history of NMS. There was no significant difference in the frequency of the poor metabolizer genotype of CYP2D6 between the cases with a history of NMS and controls (p > 0.05). The frequency of the mutation located at the HhaI site in exon 6 of CYP2D6 in the cases was higher, but not significantly (p > 0.05; the mutated allele frequency was 0.25), than that in the controls, schizophrenia patients without NMS (0.11) and healthy controls (0.09). The frequency (0.10) of the HhaI mutation type in patients with a diagnosis of SMON was also not significantly higher than in healthy controls. These results suggest that the poor metabolizer and HhaI polymorphism of CYP2D6 may not be a useful molecular marker for predicting the onset of NMS and SMON.

We have evaluated the neuronal uptake of 12 neutral and quaternary azaheterocyclic amines that are possible candidates for idiopathic Parkinson's disease via dopamine transporter of striatal synaptosomes. The double-reciprocal plots for dopamine transporter obtained from Wistar rat and C57BL/6 mouse synaptosomes with N-methyl-4-phenylpyridinium cation (MPP+) as a substrate were identical to each other. Neutral beta-carbolines and tetrahydroisoquinolines were unfavorable substrates for dopamine transporter. The quarternization of these compounds strikingly increased the affinity for dopamine transporter with 2-10 times greater Km and 10 times smaller Vmax values than MPP+. Although catechol tetrahydroisoquinolines were weak substrates, their quarternization reduced their original properties as substrates for dopamine transporter. These results provide both topographic and electrogenic information of azaheterocyclic amines for the dopamine transporter-mediated influx. The intramolecular distance between the N-atom and the centroid of the benzene ring could be an important factor for the recognition of binding site of dopamine transporter, and an adequate net charge similar to dopamine would be further required for translocation into the cells.

Previous studies have suggested that during forebrain ischemia, considerable Zn2+ is released from synaptic vesicles of gultamatergic neuronal terminals and accumulates in hippocampal CA1 pyramidal neurons, leading to delayed neuronal death. However, since a time lag exists between the accumulation of Zn2+ and the occurrence of ischemia and there are conflicting reports about the amount of Zn2+ released, the level of released Zn2+ during ischemia in vivo is still unclear. In this study, we investigated the temporal change of extracellular Zn2+ in the hippocampal CA1 area using microdialysis and the accumulation of Zn2+ in hippocampal CA1 neurons with TSQ staining in rats with a transient forebrain ischemia. The level of extracellular Zn2+ in the CA1 area increased transiently reaching a peak 15 min after occlusion, then decreased with time, returning to the basal level 15 min after reperfusion. In addition, at this peak, the level of extracellular Zn2+ was about twice the basal level. Assessment of the intracellular Zn2+ in hippocampal neurons with TSQ revealed that Zn2+ accumulate at 24 h, but not 0 and 6 h after ischemia. These results suggest that, although the synaptic vesicular Zn2+ is released into the synaptic cleft during ischemia in vivo, the amount of released Zn2+ might not be so excessive, and it does not accumulate in hippocampal CA1 pyramidal neurons immediately after ischemia.

The effects of a pyridinium metabolite (HPP+) derived from haloperidol (HP) on in vivo tyrosine hydroxylation was evaluated in freely moving rats. As an index of the in vivo activity of tyrosine hydroxylase (TH), the rat striatum was perfused with NSD-1015, and extracellular 3,4-dihydroxyphenylalanine (DOPA) levels were measured. HPP+ (1 mM) gradually reduced tyrosine hydroxylation to 30% of the basal level, although the effect was less potent than 1-methyl-4-phenylpyridinium ion (MPP+). On the contrary, HPP+ at a 0.1 mM dose decreased in 5-hydroxyindoleacetic acid (5-HIAA) level, but did not affect dopamine metabolites. The present study revealed that HPP+ irreversible inhibited in vivo tyrosine hydroxylation by the same manner of MPP+. However, the neurotoxic effects of HPP+ in vivo would be selective for serotonergic over dopaminergic neurons, which distinguishes the toxic profile of this compound compared to that of MPP+.

A simple and rapid method for the detection of 12 quaternary ammonium compounds (Suxamethonium, Pancuronium, Benzethonium, Acetylcholine, Bethanechol, Hexamethonium, Propantheline, Methylbenactyzium, Neostigmine, Distigmine, Pyridostigmine and Ambenonium) using thermospray high-performance liquid chromatography (LC)-mass spectrometry was investigated. Each compound was extracted from urine as an ion-pair with bromothymol blue, tropaeolin OO and hexanitrodiphenilamine in dichloromethane. The used LC column was Asahipak GS-320H for aqueous steric exclusion chromatography, and the mobile phase was 100 mM ammonium acetate-acetonitrile (90/10 v/v or 70/30 v/v). The ion source block and tip heater temperatures were set at 300 and 320°C, respectively. The vaporizer control temperature was kept at the temperature of the take off temperature minus 15°C. The recoveries of 12 quaternary ammonium compounds from the spiked urine were 76.1 to 98.6% by ion-pair extraction. The detection limits of these compounds for the simultaneous analysis were 0.5-80 ng/ml by selected ion monitoring mode.

In the brain, Zn 2+ is stored in synaptic vesicles of a subgroup of glutamatergic nerve terminals. Although it has been reported that this Zn 2+ is released upon the excitation of nerves in vitro, there has been little study of the release of Zn 2+ during ischemia in vivo. Here, using brain microdialysis, the release of vesicular Zn 2+ was investigated in vivo. When the vesicular Zn 2+ was released into the synaptic cleft by a depolarizing stimulation achieved by perfusion with Ringer's solution containing high K + (100 mM KCl), a significant increase in the extracellular concentration of Zn 2+ could be detected by microdialysis. Then, we investigated the release of vesicular Zn 2+ in a rat transient middle cerebral artery occlusion model using microdialysis. Consequently, the extracellular Zn 2+ level in the cortex increased within 15 min of the start of occlusion and reached a peak at 30 min, which was about twice the basal level. After 30 min, it declined with time returning to the basal level 15 min after reperfusion, which was performed after 60 min of occlusion. The results suggest that vesicular Zn 2+ would be released into the synaptic cleft during brain ischemia in vivo.

We determined cabergoline and L-dopa in human plasma using liquid chromatography-mass spectrometry with tandem mass spectrometry (LC-MS-MS). The deproteinized plasma samples with organic solvent or acid were analyzed directly by reversed-phase liquid chromatography. Using multiple reaction monitoring (MRM, product ions m/z 381 of m/z 452 for cabergoline and m/z 152 of m/z 198 for L-dopa) on LC-MS-MS with electrospray ionization (ESI), cabergoline and L-dopa in human plasma were determined. Calibration curves of the method showed a good linearity in the range 5-250 pg/ml for cabergoline and 1-200 ng/ml for L-dopa, respectively. The limit of determination was estimated to be approximately 2 pg/ml for cabergoline and approximately 0.1 ng/ml for L-dopa, respectively. The method was applied to the analysis of cabergoline and L-dopa in plasma samples from patients treated with these drugs. The precision of analysis showed coefficients of variation ranging from 3.8% to 10.5% at cabergoline concentration of 13.8-26.2 pg/ml and from 2.9% to 8.9% at an L-dopa concentration of 302.5-522.1 ng/ml in patient plasma. As a result, the procedure proved to be very suitable for routine analysis.

The content of the endogenous amine, 1-methyl-1,2,3,4-tetrahydroisoquinoline (1-MeTIQ), in mouse brain, treated with the antipsychotic agent haloperidol (HP) was determined by GC-SIM (selected ion monitoring) system. 1-MeTIQ in brain was extracted with chloroform at pH 11-12 and was detected as PFP derivative by GC-SIM. The 1-MeTIQ contents in mouse brains following intraperitoneal administration of HP or its dehydrated product, HPTP (1 and 4 mg/kg per day, for four days), were markedly reduced compared with control groups. This result agrees well with the findings in human idiopathic parkinsonianism and in MPTP-treated mouse brain. In addition, this finding suggests that the change of the endogenous amine 1-MeTIQ content in the brain plays an important role in the pathogenesis of toxin-induced parkinsonism.

1. The metabolism of chlorpheniramine (I) was examined in vivo in rats and a human volunteer; in the rats a stable isotope was used.2. In addition to the unchanged drug (I) and the N-demethylated metabolites (II and III), nine further metabolites were identified in rat urine, four of which were also found in human urine. Chlorpheniramine N-oxide (IV), 3-(p-chlorophenyl)-3-(2-pyridyl)propanol (V), 3-(p-chlorophenyl)-3-(2-pyridyl)-N-acetylaminopropane (VII) and 3-(p-chlorophenyl)-3-(2-pyridyl)-propionic acid (XIII) were identified in rat and human urine.3. The hydroxylated metabolites of the pyridyl ring of the unchanged drug, II, V and VII, and the glucuronide of XIII were identified only in rat urine. XIII was found in rat urine as long as 6 days after the last dose.We would like to thank Dr K. Saeki, Kobe Women's College of Pharmacy, for the measurement of the high-resolution mass spectra, and Miss M. Maeda for the measurement of 1 H-n.m.r.

A 20-year 3-month man who suffered severe asymmetry in the middle and lower third of face was presented. Simultaneous mobilization of maxilla and mandible (Le Fort-I Osteotomy+ Sagittal Splitting Osteotomy) was performed to flatten occlusal plane and after 6 months Genioplasty was done to correct remaining facial asymmetry.Although minimum skeletal relapse occurred quite early after the first operation, desired facial symmetry was acquired.

Arthrographic examinations were performed for 40 joints of 39 patients with internal derangement of the temporomandibular joint (TMJ) to analyse disc movement in relation to clinical signs and symptoms in each individual. The inconsistency between the arthrographic and clinical findings was often associated with soft tissue derangements, such as perforation of the articular disc and adhesion of the capsula.Therefore arthrographic examination may be indispensable to elucidate the pathologic conditions more clearly in those cases in which soft tissue derangements of TMJ are suspected or the primary treatment proved to be unsuccessful.

Clinico-statistical observation and follow-up survery on TMJ arthrosis in children below 15 years old were studied. The subjects were 22 patients who visited our hospital in the past 9 years and 8 months.Sixteen patients from 11 months to 7 years were followed up by recall or enquke after treatment.The results are summarized below:1) Initial symptom of TMJ sound only was most frequent (59.1%), and none of the children showed limitation of opening mouth as the initial symptom.2) As to present status, 9 patients (40.9%) showed isolated single symptoms (3 pain only, 4 limitation only and 2 TMJ sound only).3) Seventeen patients (77.3%) had malocclusion containing 4 crowding of anterior teeth, 3 deep bite, 3 mandibular protrusion, 3 malposition of molar teeth, 3 posterior cross bite, and 1 maxillary protrusion. Only 5 cases had normal occlusion.4) Radiographically, 10 ptients (62.5%) showed condylar displacement in the only affected sides (6 anterior positions, 2 posterior positions, 1 superior position, and 1 inferior position). In 4 cases (25.0%), the condylar head located almost in the center of mandibular fossae at both sides.5) In follow-up status, 4 patients (25.0%) had no TMJ dysfunction symptoms. Most remaining patients had suffered from TMJ sound in spite of no limitation of opening mouth.6) In 4 patients above described, 2 patients had been treated their malocclusion by orthodontists, and remaining 2 patients had been cured in our clinic by medication only or observation only.

A high-performance liquid chromatographic (HPLC) method using a fluorescence detector is described for the simultaneous determination of dibucaine and its metabolites (M-4, M-8 and M-10) in human urine. Urine samples from obstetric patients were chromatographed in a reversed-phase system. When a ultraviolet detector (320 nm) was used, some interfering peaks appeared on the chromatogram, but this interference could be overcome by employing a fluorescence detector (Ex 330 nm and Em 440 nm) instead. The calibration curves were linear in the range of 0.05-5.0 μg/ml for all compounds and the detection limits of dibucaine and its metabolites were about 5 ng/ml in urine. The urinary excretion of dibucaine and its metabolites by obstetric patients infused with Percamine S® in the spinal cord were determined. The mean cumulative amounts of dibucaine, M-4, M-8 and M-10 excreted during 10 h after administration were 1.1, 10.5, 3.5 and 1.1 % of the dose, respectively. The total urinary excretion was 16.2% of the dose. This method is sufficiently sensitive and specific to permit the determination of dibucaine and its metabolites in biological fluids.

The metabolism of benoxinate hydrochloride [2-(diethylamino)ethyl 4-amino-3-butoxybenzoate monohydrochloride; oxybuprocaine] was examined in humans after administration of a single oral dose. The drug was almost completely absorbed and was rapidly excreted in the urine (92.1% of dose in 9 h). Nine metabolites and unchanged drug were isolated from the urine and identified by comparison of TLC, GC, and GC-MS with authentic compounds. Any metabolites reflecting initial loss of the butyl side chain of benoxinate could not be detected. This suggests that the ester portion is metabolized more rapidly than the O-butyl side chain. 3-Butoxy-4-aminobenzoic acid, the hydrolyzed product of benoxinate, was primarily excreted (70-90% of dose) as the glucuronide together with a trace of the glycine conjugate (0.35% of dose). In addition, 3-butoxy-4-acetylaminobenzoic acid, 3-hydroxy-4-aminobenzoic acid, and 3-hydroxy-4-acetylaminobenzoic acid were identified, the latter two being detected partly as the glucuronides (1.20 and 1.43% of dose, respectively).

The disposition and metabolism of dibucaine were studied in rats. After intraperitoneal administration of 3H-labelled dibucaine, the blood concentration of total radioactivity reached a maximum at 10 min and declined thereafter, with a biphasic curve having half-lives of 37.7 min and 11.2 h. Radioactivity in the tissues after administration was high in small intestine, lung, spleen, liver, kidney and stomach. Urinary and fecal excretion of radioactivity were 39.4 and 49.0% of the dose, respectively, in 3 d after administration. Biliary excretion of radioactivity in bile duct-cannulated rats was 53% of the dose within 48 h. About 40% of urinary, fecal and biliary excretion was found in the basic metabolites, and about 12% of urinary excretion was in the acidic metabolites. In addition, 9.5% of urinary excretion and 39.5% of biliary excretion were conjugated metabolites which could be extracted following enzymatic hydrolysis. Most of the conjugates were glucuronides. Remaining metabolites were highly polar and water-soluble ones which were not hydrolyzed by enzyme treatment and could not be extracted into organic solvents.