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Biomedical subjects

S Toki

Publications and source records attributed to S Toki.

At least 55 records · Page 3Linked to original sources
PubMed1996

[A case of amotivational syndrome as a residual symptom after methamphetamine abuse].

We had a case of psychiatric evidence who was homeless and exhibited severe abulia and autism on detention for assault and battery. It was thought that his past history of chronic methamphetamine abuse and his familial history played some part in his showing such symptoms. His mother was alcohol dependent. He was an ACOA (adult child of alcoholics), which might have led to his chronic abuse of methamphetamine. On the other hand, it is well-known fact that the amotivational syndrome induced by marijuana abuse is typified by a diminution of ambition, productivity, and motivation. However, it has been contended that amotivational syndrome is induced not only by marijuana but also by amphetamine and its analogs, cocaine and volatile solvents. Since we positively support this view, we diagnosed the case as amotivational syndrome after long-term methamphetamine abuse. This was also a rare criminal case of amotivational state without hallucinations and delusions after methamphetamine abuse. We suggested that the crime committed in this case was closely related to crime induced by economic problems in residual states of schizophrenic offenders. This could be a case of both ACOA and methamphetamine dependence. There were unresolved alcohol- and drug-related problems in this case. Therefore, careful early intervention in a crisis, cooperation with the authorities and the institutions concerned, and comprehensive rehabilitation should be employed to resolve such alcohol- and drug-related problems.

Adult↗
PubMed1995

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.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1995

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.

Benzopyrans↗
PubMed1995

[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.

Animals↗
PubMed1995

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.

Adolescent↗
PubMed1994

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.

Animals↗
PubMed1994

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.

Androstadienes↗
PubMed1994

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.

Acetyltransferases↗
PubMed1994

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.

Acremonium↗
PubMed1993

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.

Animals↗
PubMed1993

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.

Animals↗
PubMed1992

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.

Animals↗
PubMed1992

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.

Animals↗
PubMed1992

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.

Ascorbic Acid↗
PubMed1992

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.

Animals↗
PubMed1992

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.

Animals↗