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K Tohyama

Publications and source records attributed to K Tohyama.

At least 19 recordsLinked to original sources
PubMed1992

Effects of nefiracetam, DM-9384 on amnesia and decrease in choline acetyltransferase activity induced by cycloheximide.

The effects of nefiracetam, [N-(2,6-dimethyl-phenyl)-2-(2-oxo-pyrrolidinyl)acetamide, DM-9384], a cyclic derivative of GABA, were investigated in the cycloheximide (CXM)-induced amnesia animal model using the passive avoidance task. Pre-training administration of DM-9384 attenuated the CXM-induced amnesia as indicated by prolongation of step-down latency. It protected against CXM-induced inhibition of choline acetyltransferase activity in the cerebral cortex. These results suggest that DM-9384 attenuates CXM-induced amnesia by interacting with AChergic neuronal system and enhancing protein synthesis in the brain.

Amnesia↗
PubMed1992

Formation of PhIP in a mixture of creatinine, phenylalanine and sugar or aldehyde by aqueous heating.

A mixture of 100 mM creatinine and 100 mM L-phenylalanine was heated at 60 or 37 degrees C in the presence of sugar or aldehyde. A mutagen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formed in the model system was determined by reversed-phase HPLC. Any sugars tested induced the formation of PhIP when heated at 60 degrees C, though PhIP was not detected in a mixture without sugar. Among the sugars tested, D-erythrose and D-glyceraldehyde were more productive than pentose (D-arabinose and D-ribose) and hexose (D-glucose and D-galactose) in the yield of PhIP. Moreover, PhIP was formed even when a mixture of creatinine, L-phenylalanine and D-glucose or D-ribose was incubated at 37 degrees C for a long time. Both formaldehyde and acetaldehyde also induced the formation of PhIP, though PhIP was not detected in a mixture without sugar or aldehyde even when heated at 100 degrees C. These results indicate that PhIP can be formed at low-temperature heating and that either sugar or aldehyde is essential for PhIP formation in the model system. Our data also suggest that aldehydes may be a key reactant in the formation of PhIP in aqueous heating of the mixture of creatinine and L-phenylalanine.

Acetaldehyde↗
PubMed1992

Production of multiple growth factors by a newly established human thyroid carcinoma cell line.

A multiple growth factor-producing tumor cell line (NIM-1) was newly established from a patient with thyroid cancer and remarkable neutrophilia. NIM-1 cells also caused severe neutrophilia in nude mice bearing tumors. NIM-1-conditioned medium (NIM-1CM) contained activities that supported not only granulocyte, macrophage and eosinophil colony formation of human bone marrow cells but also the growth of colony-stimulating factor (CSF)-dependent cell lines, NFS60-KX and TF-1. Northern blot hybridization analysis revealed the constitutive expression of granulocyte-CSF (G-CSF), granulocyte/macrophage-CSF (GM-CSF) and interleukin(IL)-6 mRNAs in NIM-1 cells. Enzyme-linked immunosorbent assays (ELISA) using NIM-1CM also confirmed the production of IL-1 alpha and a small amount of IL-1 beta besides G-CSF, GM-CSF and IL-6 in NIM-1 cells. In addition, unexpected production of IL-11 in NIM-1 cells was detected by northern blot hybridization analysis and by bioassay using an IL-11-dependent cell line. Therefore, NIM-1 cell line is shown to produce multiple cytokines including potentially megakaryopoietic growth factors such as GM-CSF, IL-6 and IL-11.

Adenocarcinoma, Papillary↗
PubMed1992

Backscattered electron imaging by scanning electron microscopy of regenerating peripheral nerve axons immunostained with antineurofilament antibody.

To demonstrate three-dimensional architecture of regenerating axons growing through basal lamina tubes in cryoinjured nerve graft, backscattered electron (BSE) imaging in a scanning electron microscope (SEM) was used to visualize immunostained axons. Regenerating axons immunostained with an antibody against the 200 kD neurofilament protein (RT97) were clearly visualized in BSE images as bright components pursuing an irregular, often spiral course within the basal lamina tubes, and commonly branching within the tubes. The morphology of these structures corresponded closely to that of putative regenerating axons in SEM preparations following application of the potassium hydroxide-collagenase digestion method. The present approach, however, is a considerable improvement on the latter, providing three-dimensional information together with the identification of regenerating axons.

Animals↗
PubMed1991

Involvement of serotonergic neuronal systems in the anti-amnesic action of naftidrofuryl oxalate.

The effects of naftidrofuryl oxalate on cycloheximide- and 5-hydroxytryptophan (5-HTP)-induced amnesia were investigated using a passive avoidance task in mice. Naftidrofuryl oxalate significantly improved the cycloheximide-induced amnesia. This effect of naftidrofuryl oxalate was antagonized by 5-HTP, a serotonin (5-HT) precursor, and by p-chloroamphetamine (PCA), a 5-HT releaser. Single administration of 5-HTP in combination with pargyline, a monoamine oxidase inhibitor, induced amnesia (5-HTP-induced amnesia). This amnesia was attenuated by ritanserin, a 5-HT2-selective antagonist, but not by pindolol, a 5-HT1-selective antagonist. Naftidrofuryl oxalate also attenuated the 5-HTP-induced amnesia. A binding study revealed that naftidrofuryl oxalate inhibited the binding of [3H]ketanserin to 5-HT2 receptors in mouse brain synaptic membrane in a dose-dependent fashion (IC50 = 1.42 x 10(-7) M), but did not inhibit that of [3H]serotonin to 5-HT1 receptors. These results suggest that naftidrofuryl oxalate may attenuate cycloheximide- and 5-HTP-induced amnesia by blocking 5-HT2 receptor subtypes.

Amnesia↗
PubMed1991

Different stromal cell lines support lineage-selective differentiation of the multipotential bone marrow stem cell clone LyD9.

An interleukin 3-dependent multipotential stem cell clone, LyD9, has been shown to generate mature B lymphocytes, macrophages, and neutrophils by coculture with primary bone marrow stromal cells. We report here that coculture with the cloned stromal cell lines PA6 and ST2 can support differentiation of LyD9 cells predominantly into granulocyte/macrophage colony-stimulating factor (GM-CSF)- and granulocyte (G)-CSF-responsive cells, respectively. However, these stromal cell lines were unable to support lymphopoiesis of LyD9 cells. The GM-CSF-dependent line, L-GM, which was derived from LyD9 cells cocultured with PA6 stromal cells, could differentiate into macrophages and granulocytes in the presence of GM-CSF. The L-GM line can further differentiate predominantly into neutrophils by coculture with ST2 stromal cells. The G-CSF-dependent line, L-G, which was derived from LyD9 cells cocultured with ST2 stromal cells, differentiated into neutrophils in response to G-CSF. Although the stromal cell-supported differentiation of LyD9 cells required the direct contact between LyD9 and stromal cells, a small fraction of LyD9 cells that were pretreated with 5-azacytidine could differentiate into neutrophils and macrophages without direct contact with stromal cells. These results indicate that different stromal cell lines support lineage-selective differentiation of the LyD9 stem cell and that 5-azacytidine treatment can bypass the requirement of direct contact with stromal cells, albeit with a lower frequency.

Animals↗
PubMed1991

Premature expression of the macrophage colony-stimulating factor receptor on a multipotential stem cell line does not alter differentiation lineages controlled by stromal cells used for coculture.

We are interested to know whether expression of a lineage-specific growth factor receptor is deterministic to lineage commitment during hematopoiesis. For this purpose, we introduced the human c-fms gene into the multipotential stem cell clone LyD9 and two myeloid progenitor clones, L-GM3 and L-G3, cells that differentiate in response to granulocyte/macrophage colony-stimulating factor (GM-CSF) and granulocyte (G)-CSF, respectively. Although LyD9 cells have differentiation potential to become macrophages, c-fms transfectants of LyD9 and L-GM3 cells did not differentiate in response to human macrophage (M)-CSF. However, c-fms transfectants of L-G3 cells differentiated to neutrophils in response to human M-CSF. These results indicate that the M-CSF receptor requires a specific signal transduction pathway to exert its differentiational and proliferative effects. Furthermore, the M-CSF receptor can convey a granulocyte-type differentiation signal possibly by cooperating with the G-CSF receptor signal transduction pathway. The c-fms-transfected LyD9 cells as well as the original LyD9 cells differentiated predominantly into GM-CSF- and G-CSF-responsive cells by coculturing with PA6 and ST2 stromal cells, respectively. The results indicate that differentiation lineage is not affected by premature expression of the M-CSF receptor. Instead, the stromal cell used for coculture apparently controls lineage-selective differentiation of the multi-potential stem cell line.

Animals↗
PubMed1991

Involvement of the cholinergic neuronal system and benzodiazepine receptors in alcohol-induced amnesia.

We investigated the involvement of the GABAergic and cholinergic neuronal systems and benzodiazepine (BZP) receptors in ethanol-induced amnesia using a passive avoidance task. Pretraining administration of ethanol impaired the passive avoidance response. The BZP agonist chlordiazepoxide potentiated the amnesia, while the GABA antagonists bicuculline and picrotoxin failed to affect it. The acetylcholine esterase inhibitor physostigmine partially attenuated the ethanol-induced amnesia. These results suggest that ethanol-induced amnesia is related to BZP receptors and a dysfunction of the cholinergic neuronal system.

Amnesia↗
PubMed1991

Involvement of GABAergic systems in benzodiazepine-induced impairment of passive avoidance learning in mice.

The possible involvement of GABAergic neuronal systems in benzodiazepine (BZP)-induced impairment of a passive avoidance response was investigated. Chlordiazepoxide (CDP) impaired passive avoidance when administered prior to training. The CDP-induced impairment was antagonized by pretreatment with picrotoxin, but not by pretreatment with bicuculline or post-training administration of picrotoxin. On the contrary, when combined with muscimol, the dose at which CDP impaired the response was lower than the dose at which it did so alone. The synergy of muscimol and CDP was attenuated by pretreatment with flumazenil or bicuculline. From these results, we conclude that GABAergic systems play an important role in the BZP-induced impairment of passive avoidance.

Animals↗
PubMed1991

Germline transcripts of the immunoglobulin heavy-chain and T cell receptor genes in a murine hematopoietic stem cell line LyD9 and its derivative cell lines.

We compared germline transcript levels of immunoglobulin heavy chain and T cell receptor (TcR) genes in a murine hematopoietic stem cell line, LyD9, and its derivative cell lines. LyD9 cells can be induced to differentiate into at least three lineages, namely, B lymphocyte, macrophage, and granulocyte lineages. Although C mu transcripts were found in stem cells to B lymphocytes, other myeloid-committed cells also expressed significant amounts of C mu transcripts. Germline TcR transcripts did not show good correlation with differentiation potential and stages of hematopoietic cells. During this search we identified a novel germline transcript containing the JH-C microliter sequence in LyD9 and some of its derivative cells. Expression of mRNAs for immunoglobulin- and TcR-associated molecules (lambda 5, MB1 and CD3 delta) was widespread except for lambda 5 mRNA. Among three mRNAs encoding putative recombinase proteins, RAG-1 and RAG-2 mRNAs were not expressed in any cell lines tested, while RBP-2 mRNA was expressed ubiquitously.

Animals↗
PubMed1991

Electron microscopic study of distribution of proteoglycans in bovine cornea and sclera.

To study differences in the distribution of proteoglycans and their relationships to collagen fibrils in the cornea and sclera, bovine cornea and sclera were examined histochemically using the ruthenium red (RR) staining method. RR-positive granules (30 nm in diameter) were present in association with fine filamentous materials (3 nm in diameter and 30-100 nm in length) in the interfascicular spaces of collagen bundles in both the corneal stroma and sclera. The amount of these materials was smaller in the sclera than in the cornea. The characteristic band-like arrangement of RR-positive granules connected by filamentous materials at intervals of 80-100 nm was found only in the cornea. In enzyme digestion experiments, tissue sections were treated by chondroitinase ABC, AC, and keratanase before RR staining. The RR-positive granules and their associated filamentous materials were darkly stained after chondroitinase AC or keratanase digestion, but displayed markedly lighter staining after chondroitinase ABC digestion. These results indicate that RR-positive granules and filamentous materials contain dermatan sulfate proteoglycan.

Actin Cytoskeleton↗
PubMed1991

Effects of DM-9384, a cyclic derivative of GABA, on amnesia and decreases in GABAA and muscarinic receptors induced by cycloheximide.

The effects of N-(2,6-dimethyl-phenyl)-2-(2-oxo-1-pyrrolidinyl)-acetamide [DM-9384], a cyclic derivative of GABA, were investigated in the cycloheximide (CXM)-induced amnesia animal model using the passive avoidance task. Pre- and post-training and pre-retention test administration of DM-9384 attenuated the CXM-induced amnesia as indicated by prolongation of step-down latency. Aniracetam, another cyclic derivative of GABA, also showed antiamnesic effects. Scopolamine, a muscarinic ACh receptor antagonist, and the GABA antagonists, picrotoxin and bicuculline, all antagonized the antiamnesic effects of DM-9384. CXM decreased the number of GABAA and muscarinic ACh receptor binding sites. DM-9384 not only inhibited this effect but actually increased the latter. These results suggest that DM-9384 attenuates CXM-induced amnesia by interacting with GA-BAergic and AChergic neuronal systems and enhancing protein synthesis in the brain.

Amnesia↗
PubMed1991

Regeneration through nerve allografts in the cynomolgus monkey (Macaca fascicularis).

With the use of ulnar nerves of cynomolgus monkeys, the present study examined whether basal laminae of Schwann cells can serve as conduits for regenerating axons in nerve allografts from non-human primates. A segment of ulnar nerve was transected distal to the elbow joint one week before grafting. In Group A, a distal segment of the transected nerve was transplanted, after freezing and thawing, into the ulnar nerve of another monkey, at a level that corresponded to that from which the graft was taken. In Group B (the control group), the segment of nerve was grafted in the same manner but without cryotreatment. Two weeks, five weeks, eight weeks, and five months after grafting, the graft and the host nerve were examined with light and electron microscopy. Within two weeks after grafting in Group A, after degradation of the cellular components of the Schwann cells, the basal laminae of the Schwann cells were intact in the form of tubes. Within five weeks, many regenerating axons grew out into these basal lamina tubes in the three-centimeter-long grafts and extended into the host nerve. As seen at the wrist (seven centimeters from the distal suture) five months after grafting, the axons exhibited fully mature myelination both in the graft and in the host nerve. In contrast, in Group B, in which the Schwann cells had not been disrupted by cryotreatment, cellular components and connective-tissue matrices, including basal laminae, had been degraded and had been replaced by invading cells, which filled the endoneurial spaces of the graft. Five months after grafting, axonal growth had been arrested in the graft one centimeter distal to the proximal suture. The beneficial effect in Group A appears to have been the result of the retention and preservation of intact basal laminae of Schwann cells after rapid removal of killed Schwann cells and myelin debris. Killing of Schwann cells by freezing before grafting may abolish the immune response to the Schwann cells in allografts and lead to fragmentation and disruption of myelin, which facilitates the rapid removal of myelin by macrophages.

Animals↗
PubMed1990

Involvement of AChergic systems in chlordiazepoxide induced impairment of passive avoidance response.

The chlordiazepoxide (CDP)-induced impairment of the passive avoidance response was attenuated by Ro 15-4513, a benzodiazepine inverse agonist, physostigmine and scopolamine at low doses. In a biochemical approach, CDP increased, but Ro 15-4513 decreased the acetylcholine (ACh) levels of cerebral cortex. After the training of passive avoidance, the ACh levels in the hippocampus and cerebral cortex decreased. This change disappeared by pretraining administration of CDP. These results suggest that the effect of CDP on the passive avoidance response was related to AChergic neuronal systems.

Acetylcholine↗
PubMed1990

Purification and characterization of five different alpha subunits of guanine-nucleotide-binding proteins in bovine brain membranes. Their physiological properties concerning the activities of adenylate cyclase and atrial muscarinic K+ channels.

We have purified five different alpha subunits of guanine-nucleotide-binding proteins (G proteins) from bovine brain membranes as active forms bound to guanosine 5'-[gamma-thio]triphosphate (GTP[gamma S]). All the purified alpha subunits were interacted with beta gamma subunits and served as a substrate for pertussin-catalyzed ADP-ribosylation. Based on the findings of immunoblot analyses using specific antibodies raised against various alpha subunits of G proteins, three of them were identified as alpha i-1, alpha i-2 and alpha i-3, and the other two were classified into alpha o type. One of the alpha o-type proteins was the most abundant in the brain membranes (termed alpha o), and the other (alpha o2) appeared to differ from alpha o in its proteolytic digestion data. The physiological properties of these purified GTP[gamma S]-bound alpha subunits towards adenylate cyclase and atrial muscarinic K+ channels were studied. The nucleotide-bound forms of alpha i-1, alpha i-2, alpha i-3 and alpha o2 inhibited the adenylate cyclase activity of S49 cyc- membranes which had been reconstituted with GTP[gamma S]-treated Gs; this inhibition appeared to be mainly competitive with the activated Gs, alpha i-1 having the most potent inhibitory activity among them. GTP[gamma S]-bound alpha o, however, could not inhibit the Gs-stimulated activity at all. On the other hand, all the GTP[gamma S]-bound alpha subunits activated atrial muscarinic K+ channels, accompanied by a lag time, at picomolar concentrations. The beta gamma subunits resolved from G proteins also activated the K+ channels without a lag time at nanomolar concentration. The maximum activation by the beta gamma subunits appeared to be more potent than that by any of the alpha subunits. These results suggest that alpha and beta gamma subunits might activate the K+ channels by mechanisms different from each other.

Adenosine Diphosphate Ribose↗
PubMed1990

Attenuation of benzodiazepine-induced passive avoidance deficit by post-training administration of muscimol: interaction with the cholinergic neuronal system.

We examined the involvement of GABAergic neuronal systems in benzodiazepine-induced passive avoidance deficit. Chlordiazepoxide impaired the passive avoidance response dose dependently when it was given prior to training. Post-training administration of muscimol improved the performance of chlordiazepoxide-pretreated mice. The effects of muscimol were antagonized completely by the GABAA antagonist, bicuculline, and the muscarinic acetylcholine receptor antagonist, scopolamine, but not by the benzodiazepine receptor antagonist, flumazenil, when the latter was administered immediately after training. It appears from these results that the GABAergic neuronal system plays an important role in the benzodiazepine-induced passive avoidance deficit by interacting with the cholinergic neuronal system.

Animals↗
PubMed1990

Effects of DM-9384 in a model of amnesia based on animals with GABAergic neuronal dysfunctions.

The effects of N-(2,6-dimethyl-phenyl)-2-(2-oxo-1-pyrrolidinyl)acetamide (DM-9384), a cyclic derivative of GABA, were investigated and compared with those of aniracetam in an animal model of amnesia, using a passive avoidance task with animals that have GABAergic neuronal dysfunctions. Pre- and post-training administration of DM-9384 and aniracetam ameliorated bicuculline-induced amnesia, as indicated by parameters such as % retention and step-down latency. DM-9384 ameliorated picrotoxin-induced amnesia when administered pre-training, but not when administered post-training. Aniracetam failed to improve the picrotoxin-induced amnesia. DM-9384 displaced [3H]muscimol binding to GABAA receptors (-log IC50 = 8.07 M; Hill value = 0.23 +/- 0.04), but failed to displace about 20% of the specific muscimol binding, whereas aniracetam showed only a weak effect (-log IC50 = 3.63 M; Hill value = 0.37 +/- 0.06). From these results, it appears that DM-9384 ameliorated the GABA antagonist-induced amnesia by interacting with some GABAA receptors directly and/or indirectly.

Amnesia↗