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T Ohnuki

Publications and source records attributed to T Ohnuki.

At least 55 records · Page 3Linked to original sources
PubMed1998

Comparison of binding affinities of omega-conotoxin and amlodipine to N-type Ca2+ channels in rat brain.

AIM: To compare the binding affinities of omega-conotoxin (CTX) and amlodipine to N-type Ca2+ channels in rat brains. METHODS: Whole rat brains were homogenized in HEPES buffer 50 mmol.L-1 (pH 7.4) and centrifuged at 40,000 x g to obtain the membrane-entriched fraction. 125I-omega-conotoxin (125I-omega-CTX) was used as a radioligand. Using radioligand binding assay Kd and Bmax values of the radioligand were determined by Scatchard analysis. The IC50 value for each drug was obtained from displacement experiments. RESULTS: No differences in Bmax values of 125I-omega-CTX binding sites between frozen and fresh tissues were observed. Values of Kd and Bmax of N-type Ca2+ channels were 0.02 +/- 0.01 nmol.L-1 and 1029 +/- 108 pmol/g protein, respectively. The pKi values of omega-CTX and amlodipine were 9.57 and less than 4, respectively. The pKi values of propranolol, prazosin, atropine, and histamine were very low. CONCLUSION: The binding affinity of the L-type Ca(2+)-antagonist amlodipine to N-type Ca2+ channels in the rat brain was very low.

Amlodipine↗
PubMed1998

[A case of pulmonary eosinophilic granuloma undergoing spontaneous remission].

A case of pulmonary eosinophilic granuloma that underwent spontaneous remission is presented. A 23-year old man presented with dry cough and fever. Chest X-ray film revealed diffuse reticulo-nodular infiltrates in the middle and upper lung fields. Chest CT and HRCT showed multiple cystic lesions with thick walls and small nodules predominantly in the inner zone. Based on radiographic findings, pulmonary eosinophilic granuloma was suspected. Bronchoalveolar lavage cell data showed lymphocyte and eosinophil alveolitis with no increase of CD 1 lymphocytes. The symptoms and radiographic findings improved markedly within 4 months after the onset of symptoms without treatment and upon cessation of smoking. Chest CT and HRCT showed that the cystic walls were thinner and that the small nodules had decreased. Thoracoscopic lung biopsy revealed granulomatous lesions consisting of CD 1 and S-100 protein positive histiocytes with infiltration of eosinophils and fibrous lesions. Pulmonary eosinophilic granuloma was diagnosed. There has been no recurrence for 1 year.

Adult↗
PubMed1997

Alterations in acetylcholine, NMDA, benzodiazepine receptors and protein kinase C in the brain of the senescence-accelerated mouse: an animal model useful for studies on cognitive enhancers.

The senescence-accelerated mouse (SAMP8) is a useful murine model of accelerated aging and learning deficiency. We examined bindings of [3H]pirenzepine, [3H]dizocilpine (MK-801), [3H]flunitrazepam, [3H]8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT) and [3H]phorbol 12,13-dibutylate (PDBu) in SAMP8 brains, and compared them to those of SAMR1 (control). In the hippocampus of SAMP8 at 12 months, bindings of [3H]pirenzepine, [3H]MK-801, [3H]flunitrazepam, [3H]8-OH-DPAT and [3H]PDBu were significantly lower than those in SAMR1. In the cerebral cortex, bindings of [3H]pirenzepine, [3H]flunitrazepam and [3H]8-OH-DPAT were higher in SAMP8 than in SAMR1 at 12 months. [3H]PDBu binding was decreased in both the fractions of the membrane and cytosol in the hippocampus of SAMP8. The neurochemical findings presented here support behavioral and pharmacological findings that SAMP8 is a useful model of learning dysfunction and anxiety-deficiency. The usefulness of SAMP8 in studies on cognitive enhancers is also discussed.

Aging↗
PubMed1997

Assessment of beta 2- and beta 3-adrenoceptors in rat white adipose tissues by radioligand binding assay.

We investigated the characteristics of beta-adrenoceptors (beta-ARs) in rat white adipose tissues (WAT) with a radioligand receptor binding assay using (-)-[3H]-CGP12177. Scatchard analysis revealed that there are high- and low-affinity sites for (-)-[3H]-CGP12177 in WAT. The (-)-[3H]-CGP12177 bound to a high-affinity site was displaced by 1 microM propranolol. The rank of pKi values of catecholamines for the site was isoproterenol > epinephrine > norepinephrine. By contrast, BRL37344A, BRL35135A and SR59230A, beta 3-selective agonists had high affinity for the low-affinity site of (-)-[3H]-CGP12177, whereas (-)-[3H]-CGP12177 bound to a low-affinity site was completely displaced by 100 microM bupranolol but not 1 microM propranolol. The pKi values of the catecholamines (isoproterenol, norepinephrine, epinephrine) for this site were very low. In addition, the correlation between the pKi values of various beta-agonists for the low-affinity site of rat WAT and those obtained from rat cloned beta 3-ARs was significant, but those of human cloned beta 3-ARs were not. Consequently, the results suggested that the high- and low-affinity sites were beta 2-ARs and beta 3-ARs in rat WAT, respectively.

Adipose Tissue↗
PubMed1997

[Pharmacological characteristics of the long-acting beta-blocker "bopindolol"].

The non-selective beta-blocker bopindolol, which was developed as a pro-drug, possessed 50-60 times more potent long-acting hypotensive effects on the blood pressure than those of atenolol or propranolol. Because this drug has only a mild partial agonist activity, it did not cause the rapid decrease in heart rate observed with atenolol or propranolol or the increase in heart rate induced by pindolol. These hypotensive effects are due to beta 1-antagonistic effects, not effects on beta 2- or beta 3-adrenoceptors. In addition to these effects, benefits of this drug include the following: slow dissociation rate from beta-adrenoceptors in tissues, high affinity to 5-HT1A subtypes, less clinical effects on lipid metabolism and the inhibition of renin release. It is possible that this drug possesses different pharmacological characteristics from other beta-blockers.

Adrenergic beta-Antagonists↗
PubMed1997

Affinity for [3H]iloprost binding sites and cAMP synthesis activity of a 3-oxa-methano prostaglandin I1 analog, SM-10906, in human platelets and endothelial cells.

SM-10902 ((+)-methyl [2-[(2R,3aS,4R,5R,6aS)-octahydro-5-hydroxy-4-[(E)-(3S,5S)-3- hydroxy-5-methyl-1-nonenyl]-2-pentalenyl]ethoxy]acetate) and its free acid, SM-10906 are new stable 3-oxa-methano prostaglandin (PG) I1 analogs. Their affinities for [3H]iloprost and [3H]PGE2 binding sites in human platelets and human umbilical vascular endothelial cells were compared with those of the PGI2 analog iloprost, PGE1 and PGE2 by the radioligand binding assay method. The cyclic AMP (cAMP) synthesis activity of these drugs were also determined in human umbilical vascular endothelial cells. We found that SM-10906 apparently displaced [3H]iloprost binding to the membrane fractions in those cells since the pKi values were 6.30 in platelets, 7.52 in vein endothelial cells and 6.31 in the arterial endothelial cells. The pKi values of SM-10906 for [3H]PGE2 binding sites were significantly lower than those obtained for [3H]iloprost binding. SM-10902, which is a prodrug of SM-10906, showed low affinity for [3H]iloprost binding sites in those cells. SM-10906 also dose-dependently enhanced the cAMP level in the vascular endothelial cells. Thus, these findings indicate that SM-10906 binds to [3H]iloprost binding sites and exhibits pharmacological functions such as an anti-platelet action and a cytoprotective action in endothelial cells through the elevation of intracellular cAMP contents.

Adult↗
PubMed1997

TMC-2A, -2B and -2C, novel dipeptidyl peptidase IV inhibitors produced by Aspergillus oryzae A374. I. Taxonomy of producing strain, fermentation, and biochemical properties.

TMC-2A(1), -2B (2) and -2C (3), novel dipeptidyl peptidase IV (DPIV) inhibitors, were isolated from the fermentation broth of Aspergillus oryzae A374. TMC-2A, -2B and -2C inhibited rat kidney DPIV with IC50 value of 8.1 microM, 17 microM, and 20 microM, respectively, as well as human DPIV prepared from mononuclear cells and adenocarcinoma cells. TMC-2 compounds inhibited only DPIV among the proteases tested, indicating their high selectivity for DPIV. The kinetic analyses revealed that TMC-2A was an uncompetitive inhibitor. Taxonomy and fermentation of the producing strain are also described.

Animals↗
PubMed1997

TMC-2A, -2B and -2C, new dipeptidyl peptidase IV inhibitors produced by Aspergillus oryzae A374. II. Isolation and structure determination.

New dipeptidyl peptidase IV inhibitors, TMC-2A, -2B, and -2C, were isolated from the fermentation broth of Aspergillus oryzae A374. On the basis of chemical, spectroscopic and X-ray crystallographic analyses, their structures were established to be peptide-like compounds composed of three moieties, L-tryptophan, mono- or dihydroxy-L-leucine and highly substituted isoquinoline.

Amino Acids↗
PubMed1997

[A case report of left postero-lateral thoracotomy for simultaneous CABG and left lower lobectomy].

Surgical management of patients with concomitant resectable lung lesions and critical cardiac disease is controversial. We report a case of concomitant pulmonary and cardiac surgery via a left thoracotomy. A 67-year-old male was admitted to our hospital complaining of recurrent bloody sputum and an abnormal shadow on chest X-ray. Chest CT and MRI showed a tumor in the left lower lobe (S10), with invasion of the diaphragm. A diagnosis of squamous cell carcinoma was obtained by transbronchial lung biopsy. The patient had a history of angina pectoris, and stress testing was positive. Coronary angiography showed 90% stenosis at segment 5, suggesting a risk of perioperative or postoperative myocardial infarction. This necessitated simultaneous surgical treatment for lung cancer and ischemic heart disease. A lobectomy of the left lower lung was performed, followed by coronary artery bypass grafting (CABG), using the great saphenous vein. The postoperative course was uneventful except for the occurrence of cholecystitis. Lung cancer and ischemic heart disease can be safely treated simultaneously via a single incision, with and benefit for selected patients.

Aged↗
PubMed1996

Senescence-accelerated mouse. Neurochemical studies on aging.

Senescence-accelerated mouse (SAMP8) is known as a murine model of accelerated aging and memory dysfunction. The binding activity of [3H] 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarboxam ide (PK-11195) as a neurochemical marker of gliosis markedly increased with aging in the cerebral cortex and hippocampus of SAMP8. Immunoreactivity for glial fibrillary acidic protein (GFAP) was also enhanced. A beta-amyloid precursor protein (APP)-like immunoreactivity and 27-kDa-carboxyl terminal fragments of APP increased in SAMP8 brain. In addition, anti-APP antibody stained reactive astrocytes surrounding spongy degeneration in brain stern of SAMP8. These results suggest that astrocytosis and production of APP-derived fragments occur markedly in SAMP8 brains.

Aging↗
PubMed1996

Bone marrow stromal cells produce thrombopoietin and stimulate megakaryocyte growth and maturation but suppress proplatelet formation.

Production of blood cells is regulated by the interplay of various cytokines and bone marrow stromal cells. Recently, a ligand for the orphan receptor Mpl was identified as thrombopoietin (TPO), which specifically regulates megakaryocyte differentiation, and it was reported to be expressed mainly in liver and kidney. As it was found that thrombopoietin is also produced in bone marrow stromal cells, we studied further the roles of bone marrow stromal cells on megakaryocytopoiesis and platelet formation. The stromal cells stimulated growth and maturation of bone-marrow-derived megakaryocytes in the presence of thrombopoietin, and also supported growth of BaF3 cells expressing exogenous Mpl without thrombopoietin. Thrombopoietin induces drastic morphological change of megakaryocytes in bone marrow cells in vitro, ie, the formation of lengthy beaded cytoplasmic processes (proplatelet formation). However, when the purified megakaryocytes were cocultured with the stromal cells with or without thrombopoietin, most of the megakaryocytes adhered to the stromal cells and remained unchanged, while free megakaryocytes induced proplatelet formation. These observations indicated that the stromal cells in a hematopoietic microenvironment in bone marrow secrete thrombopoietin and stimulate proliferation and maturation of megakaryocytes, but the interaction of megakaryocytes with the stromal cells may suppress proplatelet formation.

Animals↗
PubMed1996

1-[[[5-(4-Nitrophenyl)-2-furanyl]methylene]imino]-2,4-imidazolidinedione (dantrolene), an inhibitor of intracellular Ca2+ mobilization, impairs avoidance performance and spatial memory in mice.

Effects of the intracerebroventricular administration of 1-[[[5-(4-nitrophenyl)-2-furanyl]methylene]imino]-2,4-imidazolidinedi one (dantrolene, an inhibitor of intracellular Ca2+ mobilization) on learning/ memory were investigated in mice using step-through passive avoidance and radial-arm maze tests. In the passive avoidance test, the administration of 6 nmol of dantrolene shortened the response latency in the retention test. The number of times of acquisition training required to achieve the criterion latency (300 s) did not change in the acquisition test. Ten nmol of administration of dantrolene increased the number of times of acquisition training required to achieve the criterion latency in the acquisition test and shortened the response latency in the retention test. In the radial-arm maze tests, 20 nmol of administration of dantrolene disrupted maze-choice accuracy and increased error numbers. These results suggest that intraneuronal Ca2+ mobilization plays important roles in learning and memory.

Adenosine Diphosphate Ribose↗
PubMed1996

Effects of selective muscarinic antagonists, pirenzepine and AF-DX 116, on passive avoidance tasks in mice.

To clarify the physiological roles of muscarinic acetylcholine (mACh) receptor subtypes, M1 and M2, on learning and memory, we examined the effects of three antagonists, atropine (non-selective), pirenzepine (M1 selective) and 11-[[2-[(diethylamino)methyl]-1-piperidinyl]acetyl]-5, 11-dihydro-6H-pyrido[2,3-b][1,4]benzodiazepine-6-one, AF-DX 116 (M2 selective), on step-through passive avoidance tasks in mice. During acquisition tests, mice were trained repeatedly until they achieved criterion latency (300 s). In all experiments, drugs or vehicles were intracerebroventricularly administered. Pre-training (5 min before) administration of atropine (1-40 nmol) and pirenzepine (10 and 40 nmol) shortened the response latency in retention tests at 14 d after acquisition training. Pre-test (5 min before) and post-training (immediately after the acquisition training) administration of atropine slightly but not significantly impaired retention scores. The administration of AF-DX 116 did not apparently affect the scores in any of tests. Thus, the M1 receptor subtype coupling systems seem to be more important in the acquisition-consolidation process rather than in the retrieval process.

Animals↗
PubMed1996

Effects of chronic administration of bopindolol on the binding characteristics of cardiac alpha 1H-, alpha 1L-, beta 1- and beta 2-adrenoceptor subtypes in cardiac muscles of spontaneously hypertensive rats (SHR).

The effects of the chronic administration of bopindolol on the binding characteristics of [3H]CGP12177 and [3H]prazosin to cardiac alpha 1H-, alpha 1L-, beta 1- and beta 2-adrenoceptor subtypes of spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) were compared with those of two other beta-blockers, atenolol and propranolol. Bopindolol (1 and 3 mg/kg/d), atenolol (50 mg/kg/d) and propranolol (60 mg/kg/d) were given to 10-week-old SHR for 12 weeks. The changes in Kd and Bmax values of the myocardium of SHR treated without and those drugs were assessed by Scatchard analysis, and the ratio and Bmax values of the beta 1- and beta 2-adrenoceptor subtypes were also calculated from displacemental curves using ICI 118,551. The systolic blood pressure in SHR was dose-dependently lowered by the administration of bopindolol, and was also lowered by the administration of atenolol and propranolol. The Bmax values of beta 1- and beta 2-adrenoceptors were lowered by the administration of bopindolol (1 and 3 mg/kg/d) without any changes in the Kd values or the ratio of beta 1- and beta 2-adrenoceptors. Propranolol lowered 3-fold the affinity to the beta-adrenoceptor. On the other hand, the Kd and Bmax values of alpha 1H- and alpha 1L-adrenoceptor subtypes (high and low affinity binding sites for [3H]prazosin) were not changed by these drugs. These findings suggest that bopindolol had a beneficial effect on beta-adrenoceptors in the membranes of cardiac muscles of SHR, implying that these effects may contribute to lowering hypertension.

Adrenergic beta-Antagonists↗
PubMed1996

[The effect of basic fibroblast growth factor (bFGF) on early bronchial revascularization].

We examined local effects of basic fibroblast growth factor (bFGF) on early bronchial revascularization following bronchial anastomosis. The left main bronchi of mongrel dogs (8-15 kg) were cut and sutured following peripheral radical hilar stripping. The anastomotic sites were wrapped with a pericardial fat tissue pedicle, including branches of the internal thoracic artery and vein (8 dogs group A). One ml of bFGF (Biomedical Tecnologies Inc.) dissolved in 1 ml of fibrin glue (final concentration of 20 ng/ml for a total dose of 100 ng, pH 7.15-7.5) was applied to the anastomotic sites in order to deliver the bFGF gradually and selectively (12 dogs group B). At various timepoints, changes in bronchial mucosal blood flow were measured using a laser Doppler flowmeter and left internal thoracic artery (LITA) blood flow, using an implanted electromagnetic flowmeter. On the 7th postoperative day, silicone rubber was injected into the left subclavian artery, and the revascularization pattern from branches of the LITA to the bronchus was examined histologically. Specimens were labeled as (-) when the neogenic vessels were only observed outside the bronchial wall, (1+) when observed inside the bronchial wall but not in the mucosa, and (2+) when clearly observed in the mucosa. Blood flow in the bronchial mucosa was measured as the left/right ratio. For group A, the averages immediately after operation, and on the 3rd and on the 7th postoperative days, were 0.35 +/- 0.10, 0.46 +/- 0.04, and 0.70 +/- 0.14 respectively; while, for group B, they were 0.27 +/- 0.09, 0.78 +/- 0.15, and 0.90 +/- 0.15, respectively (p < 0.01). Our results show that blood flow in the LITA increased more in group B than in group A (average 2.7 +/- 1.8 ml/min in group A, vs. 4.7 +/- 2.9 ml/min in group B). Furthermore, the pathologic findings of neovascularization were (-) in 3 cases and (1+) in 2 cases in group A, while group B showed (1+) neovascularization in 1 case and (2+) in 4 cases. These results clearly demonstrate increased revascularization in the bFGF treatment group B. We conclude that local application of bFGF is effective in stimulating early bronchial revascularization.

Anastomosis, Surgical↗
PubMed1995

Characterization of the truncated thrombopoietin variants.

Thrombopoietin (Tpo) is a specific cytokine which regulates megakaryocyte differentiation and maturation. We isolated a truncated mouse Tpo cDNA, the product of which turned out to function neither as an active Tpo variant nor as an antagonist. To define the functional domains of the Tpo molecule further, various truncated and point-mutated Tpo molecules were prepared and their biological activity was assayed. It was found that deletion of the amino terminal side of a potential proteolytic cleavage site, Arg-Arg motif, caused complete loss of Tpo's activity, and that point-mutants lacking one of four conserved cysteine residues lost Tpo activity. We also noticed that Tpo activity was inhibited by the reducing agent. Thus, it was concluded that the amino terminal half of the Tpo is sufficient for Tpo activity, and that the cysteine residues, especially the last cysteine residue located two amino acids away from the Arg-Arg motif, are critical for this activity.

Amino Acid Sequence↗
PubMed1995

Identification of interaction site of pseudoazurin with its redox partner, copper-containing nitrite reductase from Alcaligenes faecalis S-6.

Pseudoazurin, a low molecular weight protein containing a single type I copper, functions as an electron donor to a copper-containing nitrite reductase (NIR) in a denitrifying bacterium Alcaligenes faecalis S-6. To elucidate the protein-protein interaction between these two copper-containing proteins, each of nine out of 13 lysine residues on the surface of pseudoazurin were independently replaced by alanine or aspartate, and the effects of the mutations on the interaction with NIR, as well as the physicochemical properties of pseudoazurin, were analyzed. All of the mutated pseudoazurins showed optical spectra and oxidation-reduction potentials almost identical to those of wild-type pseudoazurin, suggesting that none of the replacements of these lysine residues affected the environment around the type I copper site. Kinetic analysis of electron transfer between mutated pseudoazurins and NIR reveals that the lysine mutations have very little effect on the rate of electron transfer to NIR, but substitution at residues 10, 38, 57 and 77, all close to the copper site, substantially decreases the affinity of pseudoazurin for NIR. This suggests that pseudoazurin interacts with NIR through the region close to the type I copper site. The refined X-ray structures of Lys38Asp and Lys10Asp/Lys38Asp show that the molecular structure has indeed changed little. A new space group is observed for the Lys109Ala mutant crystal. Crystal packing interactions change for the Lys10Asp/Lys38Asp mutant but remain the same for Lys38Asp and Lys59Ala mutants.

Alanine↗