[A case of volatile solvent psychosis accompanied with multiple neurological and psychological symptoms]

A case of psychosis accompanied with variable symptoms induced by chronic volatile solvent inhalation is reported in this study. The patient was a 27-year-old male who had abused volatile solvents for 15 years, and was sent to the hospital because of a tonic-clonic seizure. Severe psychomotor excitement was observed on the first day and the 7th day after admission. After 10 days of admission, we observed visual transformation and hyperthermia, which suggested acute toxic symptoms due to a volatile solvent. Furthermore, symptoms such as incoherence, delusions of persecution, and catalepsy were also observed in this case. There have been few reports of multiple neurological and mental symptoms appearing in cases of volatile solvent psychosis. Although we sometimes experience cases of solvent abuse with acute mental symptoms and recurrent excitement after sedation, such symptoms are not always observed because of flashback in the strict sense. Therefore, careful early treatment should be employed to prevent 'secondary excitement'.

Changes in GABAA receptor function and cross-tolerance to ethanol in diazepam-dependent rats

Changes in gamma-aminobutyric acidA (GABAA) receptor function and their relation to cross-tolerance to ethanol (EtOH) were studied in diazepam (DZP)-dependent rats. Physical dependence on DZP was induced in male Fischer rats by using the drug-admixed food method. The 38Cl- influx into cerebral cortical synaptoneurosomes induced by 10 microM GABA in DZP-withdrawn rats was significantly increased, compared with control and DZP-tolerant rats. Although enhancement of GABA-dependent 38Cl- influx by the addition of EtOH and flunitrazepam (FZ) was recognized in the control, there was no such effect of EtOH or FZ in the DZP-tolerant animals. On the other hand, GABA-dependent 38Cl- influx was enhanced by FZ in the withdrawn group. The addition of picrotoxin and bicuculline inhibited GABA-dependent 38Cl- influx in each group. The stimulatory effect of FZ on GABA-dependent 38Cl- influx was inhibited by the addition of Ro 15-1788 in the control group. However, such an inhibitory effect was not observed in the withdrawn group. The antagonistic effect of Ro 15-4513 on EtOH stimulation of GABA-dependent 38Cl- influx observed in the control was not recognized in the withdrawn group. In a [3H]FZ assay of binding to benzodiazepine (BZ) receptors, Bmax values were significantly increased in DZP-withdrawn animals, but decreased in the DZP-tolerant group, compared with the control. When [3H]muscimol binding was examined, the Kd of high-affinity sites of the GABAA receptor in withdrawn rats was significantly lower than in the control. In low-affinity binding sites, the values of Kd and Bmax were significantly decreased, compared with those in the control. The present study indicates that GABAergic transmission involving the regulation of GABA-dependent chloride channels is altered in DZP-dependent rats. Alterations of the GABAA/BZ/chloride channel complex function may be related to the cross-tolerance between BZ and EtOH.

MS-271, a novel inhibitor of calmodulin-activated myosin light chain kinase from Streptomyces sp.--I. Isolation, structural determination and biological properties of MS-271

A novel cyclic peptide, MS-271, was isolated from the culture broth of an actinomycete, Streptomyces sp. M-271 as an inhibitor of smooth muscle myosin light chain kinase (MLCK). MS-271 inhibited the MLCK from chicken gizzard with an IC50 value of 8 microM. MS-271 did not inhibit cyclic AMP-dependent protein kinase, protein kinase C or calcium/calmodulin-dependent cyclic nucleotide phosphodiesterase at concentrations up to 400 microM. The primary structure of MS-271 was identical to that of siamycin I, an anti-HIV peptide isolated from a microbial source.

Incidence and prevalence of inflammatory bowel disease in Japan: nationwide epidemiological survey during the year 1991

The aim of this nationwide study was to determine the recent incidence and prevalence of inflammatory bowel disease, i.e., Crohn's disease (CD) and ulcerative colitis (UC), in Japan. We mailed out a preliminary examination sheet with diagnostic criteria, asking about the presence of patients with inflammatory bowel disease, to all hospitals in Japan that have more than 200 beds for general use. The rate of reply was 60.93%. A total of 4243 patients with CD were reported. The incidence per 100 000 population per annum was 0.51 (0.71 in males, 0.32 in females). The prevalence per 100 000 population per annum was 5.85 (7.94 in males, 3.83 in females). Peak age at onset was 20-24 years in males and 15-19 years in females. A total of 12559 cases of UC were reported. The incidence per 100 000 population per annum was 1.95 (2.23 in males, 1.68 in females). The prevalence per 100 000 population per annum was 18.12 (18.70 in males, 18.17 in females). Peak age at onset was 20-24 years in males and 25-29 years in females.

[Changes in GABAA/benzodiazepine receptor complex function in the pentobarbital-dependent rat. II: Strain differences between Lewis and Wistar-Kyoto rats]

We studied the differences in alterations of GABAAergic receptor function between pentobarbital (PB)-dependent female Lewis (LEW) and Wistar-Kyoto (WKY) rats. The 36Cl- influx induced by 10 microM GABA in the PB-dependent WKY was significantly lower than that in the control, while there was no significant 36Cl- influx change in both PB-dependent and control LEW. The additions of PB, flunitrazepam (FZ) and ethanol (EtOH) enhanced the GABA-dependent 36Cl- influx in control rats of both strains. However, the enhancements of 36Cl- influx by PB, FZ, EtOH were not recognized in PB-dependent WKY. On the other hand, the enhancement of GABA-dependent 36Cl- influx was observed only with the addition of PB in PB-dependent LEW. The additions of bicuculline (BIC) and picrotoxin (PIC) inhibited GABA-dependent 36Cl- influx in control rats of both strains. However, inhibition of 36Cl- influx by BIC and PIC was not recognized in the PB-dependent WKY. These results suggest that physical dependence on PB in WKY may cause greater functional alterations of the GABA/benzodiazepine receptor complex than those in LEW, and that these changes in this receptor complex may relate to the difference in the development of physical dependence on PB between the two strains.

PS-990, a novel microbial metabolite, reversibly induces neurite extension in neuroblastoma cells

PS-990, which is a novel microbial metabolite, induced neurite formation in a murine neuroblastoma cell line, Neuro2A. In the presence of PS-990 at 30 micrograms/ml, significant neurite outgrowth was observed. Cultures maintained for 12 h in the presence of PS-990 resulted in the maximal number of neurite-bearing cells, and then the neurites formed were gradually retracted. The retracted cells again yielded the neurite formation when the cells were exposed again to PS-990. PS-990 inhibited both the cell growth and thymidine incorporation into the cells at the same concentration range. Although the type of neurite formation with PS-990 is similar to that with a cyclic AMP analog and indeed PS-990 has an inhibitory potency against calcium and calmodulin-dependent cyclic nucleotide phosphodiesterase, the intracellular cyclic AMP level was not elevated when treated with PS-990. These results suggest that PS-990 reversibly induces neurite formation with arrest of the cell growth through a mechanism distinct from an increase in the intracellular cyclic AMP concentration.

Isolation of myosin light chain kinase inhibitors from microorganisms: dehydroaltenusin, altenusin, atrovenetinone, and cyclooctasulfur

Dehydroaltenusin, cyclooctasulfur, atrovenetinone, and altenusin were isolated from the culture broths of Penicillium verruculosum IAM-13756, Streptomyces verticillus subsp. tskushiensis ATCC-21633, Penicillium sp. SPC-16375, and Penicillium sp. SPC-16524, respectively, as new myosin light chain kinase (MLCK) inhibitors. These compounds inhibited the calmodulin-dependent activity of MLCK with IC50 values of 0.69, 0.86, 3.7, and 350 microM, respectively. Among them, dehydroaltenusin was the best MLCK inhibitor in terms of potency and selectivity examined in the purified enzyme systems.

Effects of a novel N-methyl-D-aspartate (NMDA) receptor antagonist, 3,3'-dimethyl-3,4,3',4'-tetrahydro-6,8,6',8'-tetramethoxy-[10,10' -bi-2- oxanthracene]-4,9,9'-(1H,1'H)-triol 4-acetate (ES-242-1), on NMDA-induced increases of intracellular Ca2+ concentration in cultured hippocampal neurons

The effects of a novel N-methyl-D-aspartate (NMDA) receptor antagonist, ES-242-1 (3,3'-dimethyl-3,4,3',4'-tetrahydro-6,8,6',8'-tetramethoxy-[10,10' - bi-2-oxanthracene]-4,9,9'-(1H,1'H)-triol 4-acetate), on NMDA-induced increases of intracellular Ca2+ concentration in cultured hippocampal neurons were examined. ES-242-1 selectively blocked the NMDA-induced increase in intracellular free Ca2+ concentration ([Ca2+]i), but not the [Ca2+]i increase stimulated by quisqualate or kainate. The effect of ES-242-1 appeared in the slow development of a blockade of [Ca2+]i (half blocking time: 90 sec) when 100 microM NMDA was applied with 10 microM ES-242-1, whereas the initial [Ca2+]i rise was attenuated by 10 microM ES-242-1 when the latter was applied with a lower concentration of NMDA (10 microM). This is consistent with a previous observation that ES-242-1 binds to both the transmitter recognition site and the channel domain. The blockade by ES-242-1 was reversed by washing. In contrast, the blockade by MK-801 was not relieved easily by washing. These results suggest that ES-242-1 blocks the NMDA-induced [Ca2+]i increase due to a combination of two well-recognized mechanisms, which are different from that of MK-801, at the NMDA receptor.

PS-990, a novel neuritogenic compound from Acremonium sp

A novel compound, PS-990, which induces differentiation of neuroblastoma cells, was isolated from the culture broth of a fungus, Acremonium sp. KY12702. PS-990 inhibited brain calcium calmodulin-dependent cyclic nucleotide phosphodiesterase with an IC50 value of 3 micrograms/ml, and markedly induced neurite extension of mouse neuroblastoma, Neuro2A, at concentrations ranging from 10 to 30 micrograms ml.

Non-systemic expression of a stress-responsive maize polyubiquitin gene (Ubi-1) in transgenic rice plants

We have used the promoter, 1st exon and 1st intron of the maize polyubiquitin gene (Ubi-1) for rice transformation experiments and revealed the characteristic expression of Ubi-1 gene: (1) Ubi-1 gene is not regulated systemically but rather individual cells respond independently to the heat or physical stress; (2) Ubi-1 gene changes its tissue-specific expression in response to stress treatment; (3) the expression of Ubi-1 gene is dependent on cell cycle.

Neurite outgrowth of PC12 cells is suppressed by wortmannin, a specific inhibitor of phosphatidylinositol 3-kinase

The effects of wortmannin (WT), an inhibitor of phosphatidylinositol (PI) 3-kinase, on differentiation of PC12 cells were analyzed. WT inhibited PI 3-kinase activity of PC12 cells at a concentration of 10(-7) M in vivo and in vitro. Transient inhibition of PI 3-kinase activity at the time of nerve growth factor stimulation had no effect on activation of the ras protein or neurite formation by the cells. However, continuous inhibition of PI 3-kinase blocked differentiation at the step just before neurite formation. When WT was applied to cells growing neurites, elongation of the neurites was stopped at that step. These results suggest that PI 3-kinase may be involved in neurite elongation.

Hexobarbital metabolism: a new metabolic pathway to produce 1,5-dimethylbarbituric acid and cyclohexenone-glutathione adduct via 3'-oxohexobarbital

1. In the presence of glutathione under physiological conditions, 3'-oxohexobarbital was non-enzymically converted to 1,5-dimethylbarbituric acid and a cyclohexenone-glutathione adduct. 2. The two reaction products were characterized by mass spectrometry, 1H- and 13C-n.m.r. spectrometry, and UV spectral analyses. 3. 1,5-Dimethylbarbituric acid was excreted in urine of rat given hexobarbital, 3'-oxohexobarbital, or 1',2'-epoxyhexobarbital, and accounted for 13.4, 14.5 and 4.7% of dose, respectively. 4. The cyclohexenone-glutathione adduct, a novel metabolite of hexobarbital, was excreted in the bile of rat given hexobarbital. 5. The route of 1,5-dimethylbarbituric acid formation via 3'-oxohexobarbital in the metabolism of hexobarbital was discussed in comparison with the epoxide-diol pathway.

The neuroprotective properties of ES-242s, novel NMDA receptor antagonists, in neuronal cell culture toxicity studies

ES-242-1, a novel bioxanthracene of microbial origin, blocked glutamate-induced neuronal death in a dose-dependent manner at concentrations ranging from 0.01 to 1.0 microM, but not the neuronal death caused by kainic acid or quisqualic acid. ES-242-1 also prevented cell death induced by 2,4-methanoglutamate, which is a specific agonist for the NMDA receptor. ES-242-1 showed protective effects in cultured neurons prepared from cerebellum and septum as it did in cultured hippocampal neurons but to different extents. There was a positive correlation between the potencies of ES-242s as inhibitors of ligand binding to the NMDA receptor and as inhibitors of neuronal death. Hypoxic treatment for 4 h under 95% N2 and 5% CO2 caused neuronal death of the cultured hippocampal neurons. Again, ES-242-1 at 1.0 microM was effective to protect neurons against hypoxic injury. ES-242 compounds are new chemical entities possessing neuroprotective properties useful in the treatment of diseases involving glutamate toxicity.

Expression of a Maize Ubiquitin Gene Promoter-bar Chimeric Gene in Transgenic Rice Plants

We have constructed a chimeric gene consisting of the promoter, first exon, and first intron of a maize ubiquitin gene (Ubi-1) and the coding sequence of the bar gene from Streptomyces hygroscopicus. This construct was transferred into rice (Oryza sativa L.) protoplasts via electroporation, and 10 plants were regenerated from calli that had been selected for resistance to exogenously supplied bialaphos. Transgenic plants grown in a greenhouse were resistant to both bialaphos and phosphinothricine at a dosage lethal to untransformed control plants. Evidence of stable integration of the transferred gene into the genome of the regenerated primary transformant plants was obtained from Southern blot analysis. In addition, northern blot analysis indicated expression and proper splicing of the maize ubiquitin gene first intron from the primary chimeric transcript in these transgenic rice plants, and western blot analysis and enzymic assays verified expression of the active bar gene product. Apparent mendelian segregation for bialaphos resistance in T(1) progeny of primary transformants was confirmed.

The ES-242s, novel N-methyl-D-aspartate antagonists of microbial origin, interact with both the neurotransmitter recognition site and the ion channel domain

ES-242-1 approximately 5 are novel microbial bioxanthracenes which do not contain nitrogen. The ES-242s inhibited the binding of [3H]TCP and [3H]CGS19755 to the N-methyl-D-aspartate (NMDA) receptor complex. They had no effect on the binding of the specific ligands for the non-NMDA receptor. The biochemical and pharmacological properties of ES-242-1 were fully examined since it is the most potent of the five compounds. ES-242-1 is highly specific for the NMDA receptor; it has no effect on other receptors. Kinetic analyses indicated that ES-242-1 inhibited the binding of [3H]TCP and [3H]CGS19755 in a competitive manner, respectively, suggesting that ES-242-1 interacts with both the transmitter recognition site and the channel domain. ES-242-1 selectively inhibited NMDA-induced Ca2+ influx in primary cultures of mouse hippocampal neurons. ES-242-1 also specifically blocked the increase in cyclic GMP accumulation induced by NMDA or L-glutamate in rat cerebellar slices. In a concentration range of 0.1-1.0 microM, ES-242-1 was as potent as MK-801 in preventing glutamate-induced neurotoxicity in primary cultures of mouse hippocampal neurons. These results show that ES-242-1 is a potent and specific antagonist for the NMDA receptor. The antagonistic properties of the ES-242s appear to be due to a novel mechanism of action at the NMDA receptor.

ES-242-2, -3, -4, -5, -6, -7, and -8, novel bioxanthracenes produced by Verticillium sp., which act on the N-methyl-D-aspartate receptor

Verticillium sp. SPC-15898 was found to produce novel metabolites, designated ES-242-2-(-)8, which were structurally related to ES-242-1. These compounds were isolated from the culture broth and the physico-chemical and biochemical properties were examined. ES-242-2-(-)8 inhibited [3H]thienyl cyclohexypiperidine ([3H]TCP) binding to rat crude synaptic membranes (CSM) with IC50 values of 0.116, 2.9, ca. 2.9, 25.3, 1.0, 59, 24, and 13 microM, respectively. None of these compounds showed inhibitory effects against the binding of [3H]kainate to its receptor, which is another subtype of the excitatory amino acid receptor.

Hydroxyl radical-mediated conversion of morphine to morphinone

1. The hydroxyl radical-mediated conversion of morphine to morphinone (MO) was examined as an alternative to the enzymic reaction. 2. Hydroxyl radicals were generated by autoxidation of ascorbate in the presence of iron and EDTA. This system oxidized morphine to MO which was identified by h.p.l.c. and t.l.c. The reaction was dependent on the concentration of added Fe2+ and required the addition of ascorbate when Fe3+ was used. 3. Catalase inhibited production of MO whereas superoxide dismutase (SOD) had no effect. Addition of a large amount of H2O2 to the system resulted in a significant decrease in production of MO. No MO production was initiated by H2O2 itself. The oxidation of morphine was inhibited by typical hydroxyl radical-scavenging agents. These results indicate that morphine undergoes oxidation to MO by hydroxyl radical.

HS-142-1, a novel non-peptide ANP antagonist, blocks the cyclic GMP production elicited by natriuretic peptides in PC12 and NG108-15 cells

HS-142-1 is a novel non-peptide antagonist for atrial natriuretic peptide (ANP) receptor. The effect of HS-142-1 on the cyclic GMP production elicited by natriuretic peptides in neuronal cell lines, PC12 and NG108-15 was examined. Natriuretic peptides such as ANP, brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP) enhanced cyclic GMP production in a dose-dependent manner. HS-142-1 inhibited cyclic GMP accumulation elicited by natriuretic peptides in a dose-dependent fashion in both cells. The results suggest that HS-142-1 will be an important tool for identification and understanding of the mechanisms by which natriuretic peptides act in nervous systems.

ES-242-1, a novel compound from Verticillium sp., binds to a site on N-methyl-D-aspartate receptor that is coupled to the channel domain

A novel compound, ES-242-1, which binds to a site on N-methyl-D-aspartate (NMDA) receptor that is coupled to the channel domain, was isolated from the culture broth of a fungus, Verticillium sp. SPC-15898. ES-242-1 inhibited the [3H]thienyl cyclohexylpiperidine ([3H]TCP) binding to rat crude synaptic membrane fractions with an IC50 value of 116 nM, but did not inhibit the [3H]kainate binding to its receptor, which is another subtype of the excitatory amino acid receptor.

In vivo formation of codeinone and morphinone from codeine. Isolation and identification from guinea pig bile

Codeinone (CO) and morphinone (MO) were isolated and identified in the bile of guinea pigs given sc injections of codeine. Authentic CO was synthesized and characterized by the NMR and mass spectra of its 2-mercaptoethanol (ME) adduct. This material was then used as the standard to identify the CO-ME adduct in the bile of codeine-treated animals. The MO-ME adduct was also identified in the bile with authentic materials prepared earlier. The results of our investigations indicated that 10.5 and 2.7% dose of CO and MO, respectively, were produced for 6 hr after the codeine was given. The metabolites were separated by preparative HPLC on a reverse phase column packed with C18 gel using a 10 mM sodium phosphate buffer, pH 6.8/CH3CN, 1:1 (v/v) as an eluate. For the further purification of metabolites, we used another reverse phase column with the same mobile phase. A structural elucidation of the ME adduct of metabolites was then performed by fast atom bombardment mass spectroscopy and 400 MHz fourier transform-NMR spectrometric analysis, and identified as (8S)-(2-hydroxyethylthio)dihydrocodeinone and (8S)-(2-hydroxyethylthio)dihydromorphinone, respectively.

Production of a triple mutant, chlorophyll-deficient, streptomycin-, and kanamycin-resistant Nicotiana tabacum, and its use in intergeneric somatic hybrid formation with Solanum melongena

In order to produce a triple mutant, sexual crosses between a chlorophyll-deficient, streptomycin-resistant mutant of Nicotiana tabacum (SA) and a kanamycin-resistant transformant of N. tabacum (KR.) were carried out. From the offspring of this cross, a triple mutant (KR-SA) was selected. In N. tabacum KR-SA, chlorophyll deficiency is due to recessive mutation in the nuclear genome, streptomycin resistance is due to a dominant mutation in the chloroplast genome, and kanamycin resistance is shown to be a dominant nuclear marker. Cell suspension protoplasts of N. tabacum KRSA were fused with callus protoplasts of Solanum melongena by dextran treatment. Somatic hybrid plants were selected for streptomycin resistance and the ability to produce clorophyll in regenerated plants. By using this selection system, green plants were recovered from two colonies. When these green plants were then tested for kanamycin resistance, all analyzed plants carried this trait. In addition, the hybrid nature of these plants was confirmed by investigation of the peroxidase isozyme. The present results show that the use of N. tabacum KR-SA in studies of somatic hybridization makes it possible to select somatic hybrid plants easily and provides information of the N. tabacum genome.

A new metabolic pathway of morphine: in vivo and in vitro formation of morphinone and morphine-glutathione adduct in guinea pig

The biliary excretion of morphine and its metabolites by guinea pigs after s.c. injection of morphine (25 mg/kg) was determined by high-performance liquid chromatography procedures. The amounts of morphinone (MO), morphinone-glutathione adduct (MO-GSH), morphine and morphine-3-glucuronide excreted over a 4-hr period were 1.27, 9.35, 1.13 and 7.54% of the administeral dose, respectively. In addition, trace amounts of morphine-GSH adduct and morphinone-cysteine adduct, derived from MO-GSH, were detected. Although MO-GSH formation from MO proceeded nonenzymatically with a relatively high rate, GSH S-transferases participated in the reaction, especially at lower GSH concentrations. Pretreatment of the animals with diethyl maleate and lithocholic acid-3-sulfate decreased the total biliary excretion of MO. On the other hand, pretreatment with naloxone increased the excretion of total MO. In vitro experiments using liver cytosolic preparations showed that lithocholic acid-3-sulfate inhibited the enzymatic formation of MO from morphine and of MO-GSH from MO. The effects of naloxone on MO formation in vitro were more complex. A reaction was stimulated at low and suppressed at higher concentrations. The results indicated that MO-GSH formation from morphine is inhibited by lithocholic acid-3-sulfate through actions on both morphine 6-dehydrogenase and GSH S-transferases. Low levels of naloxone were found to stimulate the morphine 6-dehydrogenase-mediated dehydrogenation of morphine to MO.

Stimulation mechanism of guinea pig liver-mediated reduction of naloxone by morphine

The mechanism of the stimulatory effect of morphine on the reduction of naloxone has been elucidated using guinea pig liver naloxone reductase that is identical with morphine 6-dehydrogenase. The reaction products were quantitated by means of HPLC. When naloxone was incubated with the enzyme in the presence of NAD(P)H at pH 7.4 or pH optima, the production of 6 alpha-naloxol increased according to the added amount of morphine. The stimulation was predominant with NADH at pH 7.4. Under these conditions, the production of morphinone also increased in proportion to the amount of morphine. The enzymatic reduction of naloxone proceeded even if NAD(P)H was replaced by NAD(P)+ and morphine. At a fairly low concentration of NADH (0.01 mM), the enzyme produced 6 alpha-naloxol (0.3 mM), exceeding the stoichiometric amount in the presence of 16 mM morphine. Although the Vmax values for naloxone was increased by the addition of morphine, the Km values for naloxone remained unaltered. Besides other substrates for guinea pig liver morphine 6-dehydrogenase such as codeine, normorphine and ethylmorphine also enhanced the reduction of naloxone. From these results we concluded that the stimulation of guinea pig liver-mediated reduction of naloxone by morphine is caused by the acceleration of the redox of pyridine nucleotides conducted by the enzyme. These phenomena were further supported by the experiments with the liver cytosol. In addition, we confirmed that, in the guinea pig, the biliary excretion of the metabolites, naloxol and naloxol-3-glucuronide, increased after sc injection of naloxone with morphine.

Purification and characterization of hydroxypyruvate reductase from a serine-producing methylotroph, Hyphomicrobium methylovorum GM2

Hydroxypyruvate reductase of a serine-producing methylotroph, Hyphomicrobium methylovorum GM2, was purified to complete homogeneity, crystallized and characterized, the first time for an enzyme from a methylotroph. The enzyme was found to be a dimer composed of identical subunits (38 kDa), the molecular mass of the enzyme being about 70 kDa. The enzyme was stable against heating at 25 degrees C for 10 min at pH values between 5 and 9. Optimal activity was observed at pH 6.8 and around 45 degrees C. The enzyme catalyzed the reduction of hydroxypyruvate with the oxidation of only NADH. Other than hydroxypyruvate, only glyoxylate served as a substrate. The Km values were found to be 0.175 mM for hydroxypyruvate and 10.8 mM for glyoxylate. Taking advantage of the high substrate specificity of this enzyme, a means of enzymatic determination of hydroxypyruvate was established.

(8S)-(glutathion-S-yl)dihydromorphinone, a novel metabolite of morphine from guinea pig bile

A novel glutathione-conjugated metabolite of morphine has been isolated from the bile of guinea pigs given morphine. The metabolite was separated by preparative HPLC on a reverse phase column (YMC-GEL C18) using methanol/water (1:4, v/v) as eluate and purified by HPLC on another reverse phase column (mu-Bondapak phenyl) using water/acetonitrile/trimethylamine/acetic acid (150:3:2:1, v/v) as a mobile phase. The unambiguous structure assignment of the metabolite was performed by fast atom bombardment mass spectrometry and 400 MHz fourier transform NMR spectrometric analysis, and it was identified as (8S)-glutathion-S-yl)dihydromorphinone, in comparison with the synthetic morphinone-glutathione adduct.

Purification and characterization of a serine hydroxymethyltransferase from an obligate methylotroph, Hyphomicrobium methylovorum GM2

A serine hydroxymethyltransferase was purified to complete homogeneity from a serine-producing obligate methylotroph, Hyphomicrobium methylovorum GM2. The enzyme has a molecular mass of about 98 kDa and consists of two subunits of identical molecular mass. The holoenzyme exhibits absorption maxima at 280 nm, 340 nm and 415 nm in potassium phosphate buffer, pH 7.3, the last of which shifts with a change in pH (6.0-7.5) and contains 2 mol pyridoxal phosphate/mol enzyme. The holoenzyme is converted to the apoenzyme on incubation with phenylhydrazine and reconstituted on the addition of pyridoxal phosphate. The enzyme activity was inhibited on the addition of several sulfhydryl-modifying reagents and then recovered with 2-mercaptoethanol. One sulfhydryl group per subunit was found to be responsible for the activity. Isoelectric focusing showed that the enzyme has a pI of 5.6. The Km values for glycine, L-serine and DL-beta-phenylserine are 0.046 mM, 0.15 mM and 33 mM respectively.

Guinea-pig liver morphine 6-dehydrogenase as a naloxone reductase

Elution profiles of guinea-pig liver naloxone reductase and morphine 6-dehydrogenase on Matrex green A, Sephadex G-100 and DEAE-cellulose (DE32) column chromatography used sequentially in the purification procedure were identical. The ratios of the two enzyme activities were almost constant throughout all the purification steps. The two enzymes were similarly more stable at pH 6.0 than at pH 8.0 on storage at 4 degrees. The reversible inactivation of the two enzymes by the removal of 2-mercaptoethanol from the enzyme solution was the same. Inhibitory effects of lithocholic acid, CuSO4, quercitrin, phenylarsine oxide, and prostaglandin E1 on the two enzymes were almost the same. These results indicated that naloxone reductase is identical to morphine 6-dehydrogenase in the guinea-pig liver. For the reduction of naloxone, the enzyme utilized either NADPH or NADH as cofactor, and pH optima were 6.8 with NADPH and 6.2 with NADH. The Km values for NADPH and NADH were 6.5 and 2.2 microM respectively. The Vmax values for naloxone were 1.2 units/mg protein with NADPH and 0.5 unit/mg protein with NADH. The Km values for naloxone were 0.27 mM with NADPH and 0.44 mM with NADH. The reaction product formed by the enzyme was identified as 6 alpha-naloxol by thin-layer and gas-liquid chromatographic analyses. Accordingly, it is clear that the enzyme catalyzes the stereospecific reduction of naloxone to form the 6 alpha-hydroxyl congener.

Crystalline serine hydroxymethyltransferase from an obligate methylotroph, Hyphomicrobium methylovorum

Optimal culture conditions of a methylotrophic Hyphomicrobium methylovorum and improved purification of serine hydroxymethyltransferase from the bacterium were established for the large-scale preparation of the enzyme. The first crystalline serine hydroxymethyltransferase from the microbial source was obtained in the apo form and found to be homogeneous. Amino acid analysis revealed that the enzyme had higher value per subunit for acidic and neutral amino acids than that from rabbit liver. The carboxy-terminal amino acid analysis suggested the sequence -Ile-Ala-Tyr.

Effects of glutathione and phenobarbital on the toxicity of codeinone

The ability of sulfhydryl compounds to provide protection against the acute toxicity of codeinone, a toxic metabolite of codeine, was investigated in mice. Subcutaneous administration of codeinone produced a slight reduction in hepatic glutathione concentration. Pretreatment of the mice with glutathione or cysteine significantly increased the survival rate for mice given a lethal dose of codeinone (10 mg/kg). The lethality of codeine was lowered by naloxone, whereas that of codeinone was not blocked by naloxone. The strychnine-like convulsant action of codeinone could be prevented by phenobarbital pretreatment. Glutathione pretreatment reduced the amounts of radioactivity in tissues of mice injected with [N-methyl-3-H]codeinone. A possible explanation for these observations is that glutathione reacts in vivo with codeinone and plays a role as a scavenger of this compound. This assumption is supported by the observation that codeinone reacts non-enzymatically with glutathione under physiological conditions.

In vitro formation of codeinone from codeine by rat or guinea pig liver homogenate and its acute toxicity in mice

In vitro metabolism of codeine was investigated by using a 9000 g supernatant fraction of rat or guinea pig liver homogenate. When a mixture of [N-14CH3] and [C-6-3H]codeine was incubated with the rat liver 9000 g supernatant fraction in the presence of NAD, formation of codeinone, morphine and norcodeine was detected. Replacement of NAD with NADP abolished only the formation of codeinone. On the other hand, when the guinea pig liver homogenate was used in the presence of NAD, codeinone was the main metabolite of codeine. NADP was also ineffective in forming codeinone with the guinea pig liver homogenate. The acute toxicity of codeinone was thirty times higher than that of codeine. The roles of codeinone as a metabolic intermediate and in the acute toxicity of codeine are discussed.

Purification and characterization of guinea pig liver morphine 6-dehydrogenase

Morphine 6-dehydrogenase, which catalyzes the dehydrogenation of morphine to morphinone, has been purified about 440-fold from the soluble fraction of guinea pig liver with a yield of 38%. The purified enzyme was a homogeneous protein on polyacrylamide gel disc electrophoresis and isoelectric focusing. The molecular weight and isoelectric point of the enzyme were 29,000 and 7.6, respectively. The enzyme utilizes both NAD and NADP as a cofactor, and the Km values were 0.12 mM for NAD and 0.42 mM for NADP. The Vmax values for morphine were 588 milliunits/mg of protein (with NAD) and 1600 milliunits/mg of protein (with NADP). The Km values for morphine were 0.12 mM (with NAD) and 0.49 mM (with NADP). The enzyme also exhibited activity for morphine-related compounds: nalorphine, normorphine, codeine, and ethylmorphine; however, 7,8-saturated congeners such as dihydromorphine and dihydrocodeine were poor substrates. The enzyme was inactivated by removal of 2-mercaptoethanol from the enzyme solution. The inactivated enzyme was rapidly recovered by the addition of 2-mercaptoethanol. Phenylarsine oxide and CdCl2 (dithiol modifiers) inhibited competitively toward cofactor binding and noncompetitively toward morphine binding. These results suggest that the enzyme possesses the essential thiol groups, probably vicinal dithiol, at or near the cofactor-binding site. Using the partially purified enzyme, 8-(2-hydroxyethylthio)dihydromorphinone was isolated as the product and identified by UV, mass, and NMR spectra. It was confirmed that morphinone proposed as the dehydrogenation product was nonenzymatically and covalently bound to 2-mercaptoethanol. Accordingly, the isolated morphinone-2-mercaptoethanol conjugate must be formed by two steps: enzymatic production of morphinone from morphine and then nonenzymatic binding of 2-mercaptoethanol to morphinone.

Biotransformation of N-methylcyclobarbital in vivo in rabbit and rat

Metabolism of N-methylcyclobarbital in the rabbit and rat has been studied in vivo for the purpose of comparison with the C5-methylated analogue, hexobarbital. In the rabbit, the main route of the metabolism of N-methylcyclobarbital is glucuronide formation after hydroxylation at the 3'-position of the parent compound. Dehydrogenation of the 3'-hydroxy product, a major pathway in the metabolism of hexobarbital, was a minor route in the case of N-methylcyclobarbital. In addition, a new type of metabolite, thought to be dihydroxylated products from spectral studies, was isolated. In the rat, there were almost no differences in the metabolic fates of N-methylcyclobarbital and hexobarbital. Profiles of metabolism of four analogous barbiturates (N-methylcyclobarbital, hexobarbital, cyclobarbital and norhexobarbital), which have a cyclohexene ring on the 5-carbon, reveal the contribution of alkyl substituents in the barbiturate ring on the bioavailability and metabolism of these compounds.

Studies on the mechanism of covalent binding of morphine metabolites to proteins in mouse

The disposition of N--14CH3-labeled and C-6--3H-labeled morphines in mouse tissue was determined over 48 hr after sc injection. 3H radioactivity in tissues decreased more rapidly than 14C radioactivity, and 14C activity at 48 hr after injection was 2 to 3 times greater than 3H activity in brain, blood and liver. Only 14C radioactivity in the brain and other tissues accumulated significantly by repeated co-administrations of N--14CH3- and C-6--3H-morphines. However, 3H radioactivity did not show much accumulation in brain. The ratio of 14C radioactivity irreversibly bound to macromolecules (insoluble in HCl-methanol) to the total radioactivity increased with time in the liver. [14C]Morphinone-cysteine conjugate was detected in proteolytic digests of mouse liver protein dosed with radiolabeled morphine. Morphinone-glutathione conjugate was also detected in an incubation mixture of morphine and cytosol fraction of mouse liver. These results seem to indicate that morphine is metabolized to morphinone, which then binds covalently to the thiol group of cysteine residues in protein.

Effect of morphinone on opiate receptor binding and morphine-elicited analgesia

Specific binding of 3H-naloxone to opiate receptors was found to be irreversibly inactivated by morphine. This inactivation exhibited pseudo-first-order kinetics. The presence of sulfhydryl compounds or morphine during incubation with morphinone proved good protection. Morphinone-pretreated mice blocked the analgesic effect of morphine. The possible mechanism for these observations is proposed as follows: morphinone binds covalently to sulfhydryl group of opiate receptors, and inactivates irreversibly opiate binding sites, thus blocking the analgesic effect of morphine.

Protective effect of sulfhydryl compounds on acute toxicity of morphinone

The ability of sulfhydryl compounds to provide protection against the acute toxicity of morphinone was investigated in mice. Subcutaneous administration of morphinone produced a reduction of hepatic non-protein sulfhydryl concentration. Pretreatments of mice with glutathione or cysteine significantly increased the survival rate of mice given a lethal dose of morphinone, whereas morphinone lethality was markedly potentiated by diethyl maleate. On the other hand, the administration of morphine produce a dose dependent reduction of hepatic non-protein sulfhydryl contents. However, neither glutathione nor cysteine protected mice from the acute toxicity of morphine. A possible explanation for these observations was proposed as follows: morphine is oxidized by morphine 6-dehydrogenase to morphinone, and the morphinone thus produced decreases the sulfhydryl contents in the liver. This mechanism is supported by the fact that morphinone reacts easily with glutathione and cysteine in vitro.

Stereoselective formation of glucuronides in metabolism of hexobarbital enantiomers in vivo: isolation and quantitation of glucuronides in rabbit urine

An improved column-chromatographic method was described for isolation and purification on preparative scale of a glucuronide from urine of rabbits administered (RS)-hexobarbital. The analytically pure preparation obtained was found to be a mixture of two glucuronides of diastereomeric 3'-hydroxyhexobarbitals. Rates of hydrolysis of the glucuronides were dependent on the enzyme preparations used as well as on the configuration of the substrate. For quantitative determination, the glucuronides were hydrolyzed completely by beta-glucuronidases from either Escherichia coli or abalone entrails under the conditions used. In vivo studies on the metabolism of (R)-(-)- and (S)-(+)-hexobarbital in the rabbit showed that the glucuronides excreted in 24-hr urine accounted for about 30% of the dose of each enantiomer, and that conjugation of the hydroxy isomers with glucuronic acid was so stereoselective that the isomers with S-configuration at the 3'-position were preferentially conjugated. There were almost no differences in the urinary metabolite profile between normal an PB-treated rabbits; however, a noticeable change was observed in recovery of unchanged (S)-hexobarbital after phenobarbital treatment.

Preparation of four optical isomers of hydroxylated hexobarbital and activities of 3-hydroxyhexobarbital dehydrogenase from guinea pig and rabbit liver

The preparation of four optical isomers of 3'-hydroxyhexobarbital [5-(3'-hydroxy-1'-cyclohexen-1'-yl)-1,5-dimethylbarbituric acid] is described. The absolute configuration of the four isomers were assigned as (3'S, 5 R) and (3'R, 5R) for alpha- and beta-isomers from (R)-(--)-hexobarbital, respectively. Some of these isomeric 3'-hydroxyhexobarbitals, which are formed in the reaction of hexobarbital with liver microsomal mono-oxygenase, are oxidized to 3'-oxohexobarbital [5-(3'-oxo-1'-cyclohexen-1'-yl)-1,5-dimethylbarbituric acid] by dehydrogenase localized in the soluble fraction of liver homogenates. Comparison of activities among the four isomers for 3-hydroxyhexobarbital dehydrogenase was made by use of enzymes from guinea pig and rabbit liver. It became evident that either enzyme had a quite different activity towards each optical isomer, and the configuration of the 3'-position of hydroxyhexobarbital was an important factor affecting the reactivity of enzyme; isomers with 3'S-configuration were preferentially dehydrogenated to enantiomers with 3'R-configuration. Both enzymes had the highest activity towards (3'S, 5R)-3'-(--)-hydroxy-(--)-hexobarbital, irrespective of their having specificity towards different types of substrates.

Dehydrogenation of indanol by rabbit liver 3-hydroxyhexobarbital dehydrogenase

1. Among the several enzyme activities in rabbit liver cytosol able to dehydrogenate 1-indanol, only the main activity was not separable from 3-hydroxyhexobarbital dehydrogenase during purification including polyacrylamide gel disc electrophoresis. 2. Results of mixed substrate method indicated that the same enzyme catalyses the dehydrogenation of 1-indanol and 3-hydroxyhexobarbital. The ratio between the two dehydrogenation activities was almost constant as the enzyme underwent thermal inactivation. The Ki values of p-chloromercuribenzoate, the Km values for NAD+, and the Km values for NADP+ were very similar for the two dehydrogenations. These results lead to the conclusion that the same enzyme catalyses the dehydrogenation of 3-hydroxyhexobarbital and 1-indanol. 3. 1-Tetralol, 1-acenaphthenol, 9-fluorenol, thiochroman-4-ol and 4-chromanol also served as substrate of the enzyme, but 2-indanol, 2-tetralol, and trans- and cis-indan-1,2-diol were not oxidized. 4. Reversibility of the reaction was also confirmed using 1-indanone as substrate.

Purification and properties of a new testosterone 17beta-dehydrogenase (NADP+) from guinea-pig liver

As a result of studies of guinea-pig live testosterone 17beta-dehydrogenase (NADP+) (EC 1.1.1.64), a new testosterone 17beta-dehydrogenase was discovered. The new enzyme was purified to a single homogeneous protein from the 105 000 g-supernatant fraction of guinea-pig liver by (NH4)2SO4 fractional precipitation and two gel-filtration stages, DEAE-cellulose column chromatography and hydroxyapatite column chromatography. It was characterized by many properties. The enzyme has almost the same properties as the classical testosterone 17beta-dehydrogenase (NADP+) (EC 1.1.1.64), with respect to cofactor requirement, pH optima for dehydrogenation, effect of phosphate ion on the NAD+-dependent reaction and molecular weight, but characteristic differences were observed in substrate-specificity between the two dehydrogenases. With various androstane derivatives, the configuration of the A/B-ring junction was closely connected with enzyme activity. 5alpha-Androstanes, such as 5alpha-androstane-3alpha,17beta-diol, 5alpha-androstane-3beta,17beta-diol and 17beta-hydroxy-5alpha-androstan-3-one, and 5beta-congeners, such as 5beta-androstane-3alpha,17beta-diol, 5beta-androstane-3beta,17beta-diol and 17beta-hydroxy-5beta-androstan-3-one, served as substrates for both the EC 1.1.1.64 enzyme and the new enzyme. The EC 1.1.1.64 enzyme oxidized testosterone more rapidly than did the new enzyme. These comparisons were based on the relative activities, apparent Km values and apparent Vmax values.

Guinea pig liver 3-hydroxyhexobarbital dehydrogenase. Purification and properties

3-Hydroxyhexobarbital dehydrogenase, which catalyzes the reversible oxidation of 3-hydroxyhexobarbital to 3-oxohexobarbital, has been purified 470-fold from the soluble fraction of guinea pig liver with a yield of 47%. The specific activity of the purified enzyme is 9.4 units/mg of protein. Results of polyacrylamide gel disc electrophoresis and isoelectric focusing indicated that the purified enzyme preparation is a single and homogeneous protein. NADP+ served as preferred co-factor, but NAD+ is also utilized in the presence of phosphate ion. The guinea pig liver enzyme possessed a relatively narrow substrate specificity in comparison with the rabbit liver enzyme. It is very distinctive that guinea pig liver 3-hydroxyhexobarbital dehydrogenase catalyzes the dehydrogenation of 17beta-hydroxysteroids such as testosterone, 4-androstene-3beta,17beta-diol, 5alpha-androstane-3alpha,17beta-diol, 5alpha-androstane-3beta,17beta-diol, 5alpha-androstan-17beta-ol-3-one, and 5beta-androstane-3alpha,17beta-diol.