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Biomedical subjects

Y Hashimoto

Publications and source records attributed to Y Hashimoto.

At least 163 records · Page 9Linked to original sources
PubMed2000

NKT cells in the rat: organ-specific distribution of NK T cells expressing distinct V alpha 14 chains.

Rat invariant TCR alpha-chains and NKT cells were investigated to clarify whether CD1d-mediated recognition by NKT cells is conserved further in evolution. Rats had multiple-copies of TRAV14 genes, which can be categorized into two types according to the diversity accumulated in the CDR2 region. Rats retained invariant TCR alpha forms with the homogeneous junctional region similar to mouse invariant TRAV14-J281. The proportion of invariant TCR among V alpha 14+ clones was 12.9% in the thymus and increased in the periphery, 31% in the spleen and 95% in hepatic sinusoidal cells. The invariant TRAV14-J281 was expressed by liver sinusoidal and splenic NKT cells with CD8, CD44high, and TCR V beta 8. Type 1 invariant TCR alpha was expressed more frequently in hepatic lymphocytes, while type 2 invariant TCR alpha was expressed predominantly in the spleen. Both types of cells cytolyzed to and were stimulated to proliferate by CD1d-expressing cells in a CD1d-restricted manner. These results suggested that rat NKT cells bearing distinct V alpha 14 chains are distributed in a tissue-specific pattern. NKT cell populations in rats were more variable than those in mice, indicating that they play novel roles in nature. The implication of the molecular interaction between the structurally diverse invariant TCR alpha and CD1d/ligand complex in different organs is discussed.

Amino Acid Sequence↗
PubMed2000

Role of histamine H(1) receptor in pain perception: a study of the receptor gene knockout mice.

To study the participation of histamine H(1) receptors in pain perception, histamine H(1) receptor knockout mice were examined for pain threshold by means of three different kinds of nociceptive tasks. These included assays for thermal nociception (hot-plate, tail-flick, paw-withdrawal), mechanical nociception (tail-pressure), and chemical nociception (abdominal constriction, formalin test, capsaicin test) which evoked pain by the activation in nociceptive Adelta and C fibers. The mutant mice lacking histamine H(1) receptors showed significantly fewer nociceptive responses to the hot-plate, tail-flick, tail-pressure, paw-withdrawal, formalin, capsaicin, and abdominal constriction tests. Sensitivity to noxious stimuli in histamine H(1) receptor knockout mice significantly decreased when compared to wild-type mice. This data indicates that histamine plays an important role in both somatic and visceral pain perceptions through histamine H(1) receptors. The difference in the effect of histamine H(1) receptors antagonist, the active (D-) and inactive (L-) isomers of chlorpheniramine on ICR mice further substantiates the evidence of the role of histamine H(1) receptors on pain threshold.

Animals↗
PubMed2000

NZB mice exhibit a primary T cell defect in fetal thymic organ culture.

Defects in T cell development have been suggested to be a factor in the development of systemic autoimmunity in NZB mice. However, the suggestion of a primary T cell defect has often been by extrapolation, and few direct observations of T cell precursors in NZB mice have been performed. Moreover, the capacity of NZB bone marrow T cell precursors to colonize the thymus and the ability of the NZB thymic microenvironment to support T lymphopoiesis have not been analyzed. To address this important issue, we employed the fetal thymic organ culture system to examine NZB T cell development. Our data demonstrated that NZB bone marrow cells were less efficient at colonizing fetal thymic lobes than those of control BALB/c or C57BL/6 mice. In addition, NZB bone marrow cells did not differentiate into mature T cells as efficiently as bone marrow cells from BALB/c or C57BL/6 mice. Further analysis revealed that this defect resulted from an intrinsic deficiency in the NZB Lin-Sca-1+c-kit+ bone marrow stem cell pool to differentiate into T cells in fetal thymic organ culture. Taken together, the data document heretofore unappreciated deficiencies in T cell development that may contribute to the development of the autoimmune phenotype in NZB mice.

Animals↗
PubMed2000

Inhibition of human plasma cholinesterase and erythrocyte acetylcholinesterase by nondepolarizing neuromuscular blocking agents.

PURPOSE: The kinetics of the inhibition of human plasma cholinesterase (ChE) and erythrocyte acetylcholinesterase (AChE) by alcuronium, atracurium, d-tubocurarine, pancuronium, pipecuronium, and vecuronium were studied in blood drawn from 35 surgical patients. METHODS: The activities of plasma ChE and erythrocyte AChE were determined by the calorimetric method of Ellman et al., using acetylthiocholine as the substrate. Lineweaver-Burk plots and Dixon plots were used for the analysis of the kinetics of both enzymes. RESULTS: The dissociation constants (K(m)) of plasma ChE and erythrocyte AChE were 5.00 x 10(-5) M and 5.28 x 10(-5) M, respectively, indicating that both enzymes have similar affinity to acetylthiocholine. Both Lineweaver-Burk plots and Dixon plots indicated that the six nondepolarizing neuromuscular blocking agents (NMBAs) at different concentrations induce linear mixed-type inhibition. The apparent inhibition constants (K(i)) of pancuronium (8.72 x 10(-8) M) and vecuronium (3.53 x 10(-7) M) for plasma ChE inhibition were lower than that of neostigmine (7.36 x 10(-7) M), whereas those of the six nondepolarizing NMBAs for erythrocyte AChE were markedly higher than that of neostigmine. CONCLUSIONS: Both plasma ChE and erythrocyte AChE were inhibited by six nondepolarizing NMBAs, and the pattern of inhibition of both enzymes was of mixed type. The inhibitory potencies of pancuronium and vecuronium for plasma ChE were larger than that of neostigmine, whereas those of the six nondepolarizing NMBAs for erythrocyte AChE were markedly lower than that of neostigmine. The rank order of relative potency for plasma ChE was pancuronium > vecuronium > pipecuronium > alcuronium > d-tubocurarine > atracurium.

Journal Article↗
PubMed2000

Role of apoptosis in cisplatin-induced toxicity in the renal epithelial cell line LLC-PK1. Implication of the functions of apical membranes.

The role of apoptosis and the implications of the functions of apical membranes in cisplatin-induced nephrotoxicity were investigated using the kidney epithelial cell line LLC-PK1. When LLC-PK1 cells were treated with 30 microM cisplatin, the number of floating cells was increased markedly. However, the number was not increased by treatment with 1 mM cisplatin, suggesting that different mechanisms were involved in the toxicities of these two treatments. DNA fragmentation, condensation of nuclear chromatin, and the absence of trypan blue staining suggested that cellular toxicity following treatment with 30 microM cisplatin for 24 hr was mediated predominantly by apoptosis. Specific activities of apical enzymes (gamma-glutamyltransferase, EC 2.3.2.2; and alkaline phosphatase, EC 3.1.3.1) in LLC-PK1 cells were decreased markedly by treatment with 30 microM cisplatin for 24 hr, whereas neither lactate dehydrogenase (LDH; EC 1.1.1.27) release nor a decrease in cellular protein content was observed following the same treatment. In addition, concomitant treatment with reduced glutathione completely attenuated both the apoptosis and the decrease of apical enzyme activities induced by 30 microM cisplatin. Neither DNA fragmentation nor condensation of chromatin was induced by treatment with 1 mM cisplatin for 12 hr. However, LDH release and a decrease in cellular protein level were induced by 1 mM cisplatin, suggesting that the toxic effect was due to necrosis. Under these conditions, specific activities of apical enzymes were not decreased. These results suggested that apoptosis was more responsible than necrosis for the loss of apical functions in cisplatin-induced toxicity in LLC-PK1 cells.

Animals↗
PubMed2000

Antagonistic effects of [Nphe1]nociceptin(1-13)NH2 on nociceptin receptor mediated inhibition of cAMP formation in Chinese hamster ovary cells stably expressing the recombinant human nociceptin receptor.

Nociceptin/orphanin FQ (NC) is the endogenous ligand for the nociceptin receptor (NCR) which is negatively coupled to adenylyl cyclase to inhibit the formation of cAMP. In this study we describe the inhibitory action of the novel NC analogue, [Nphe1]nociceptin(1-13)NH2 on cAMP formation in Chinese hamster ovary cells expressing the human NCR. NC, NC(1-13)NH2, the pseudopeptides [Phe1psi(CH2-NH)Gly2]NC(1-17)NH2 and [Phe1psi(CH2-NH)Gly2]NC(1-13)NH2, the hexapeptide, acetyl-Arg-Tyr-Tyr-Arg-Trp-Lys-NH2 and buprenorphine all produced a concentration dependent inhibition of forskolin stimulated cAMP formation. This inhibition was competitively reversed by [Nphe1]NC(1-13)NH2 with essentially identical pA2 values (6.12-6.48). [Nphe1]NC(1-13)NH2 showed per se a negligible residual agonist activity (alpha < 0.15).

Animals↗
PubMed2000

Pentagalloylglucose, an antisecretory component of Paeoniae radix, inhibits gastric H+, K(+)-ATPase.

We purified a compound with strong inhibitory effect on H+, K(+)-ATPase from Paeoniae radix, which has been used in Japan for the treatment of gastritis and peptic ulcers. The compound was identified as 1,2,3,4,6,-penta-o-galloyl-beta-D-glucose by proton nuclear magnetic resonance, carbon-13 nuclear magnetic resonance, and fast atomic bombardment mass spectrometry. The IC50 of the compound for H+, K(+)-ATPase was 166 nmol/l. Kinetic analyses indicated that the inhibition of the enzyme by pentagalloylglucose was noncompetitive with respect to K+. Pentagalloylglucose had relatively weak inhibitory effects for Mg(+)-ATPase (IC50: > 10 mumol/l) and Na+, K(+)-ATPase (IC50: 2.7 mumol/l). Pentagalloylglucose also inhibited the accumulation of [14C]aminopyrine in parietal cells that had been isolated from guinea pig stomach and stimulated by 10 mumol/l histamine (IC50: 7.8 mumol/l) and 1 mmol/l dbc-AMP (IC50: 10 mumol/l). These results suggest that pentagalloylglucose is a potent inhibitor of H+, K(+)-ATPase and may be responsible for inhibition of acid secretion by Paeoniae radix.

Aminopyrine↗
PubMed2000

Cleavage and inactivation of antiapoptotic Akt/PKB by caspases during apoptosis.

The oncogene Akt/PKB/RAC-PK is a serine/threonine kinase that mediates survival signals and has protective effects against apoptosis induced by a variety of stimuli. The kinase activity of Akt has been demonstrated to be critical in transmitting survival signals. We found that Akt protein was down-regulated during apoptosis. The down-regulation was blocked by a caspase inhibitor, indicating that Akt was cleaved by caspases during apoptosis. The Akt protein incubation with active caspases in vitro revealed that it was cleaved at three sites to produce 40- and 44-kDa fragments. The two cleavage sites were between the NH(2)-terminal pleckstrin homology domain (PH domain) and the kinase domain (TVAD(108 downward arrow)G and EEMD(119 downward arrow)F) and in the COOH-terminal regulatory domain (SETD(434 downward arrow)T). The loss of COOH-terminal domain of the Akt protein reduced its kinase activity and the overexpression of NH(2)-terminal and COOH-terminal-deleted Akt fragment increased the sensitivity to apoptosis-inducing stimuli. These results indicate that caspase-dependent cleavage of anti-apoptotic Akt turns off the survival signals, resulting in the acceleration of apoptotic cell death.

Apoptosis↗
PubMed2000

Phosphane Sulfide/Octacarbonyldicobalt-Catalyzed Pauson - Khand Reaction Under an Atmospheric Pressure of Carbon Monoxide.

Convenient access to cyclopentenones is provided by catalytic intra- and intermolecular Pauson - Khand reactions in the presence of octacarbonyldicobalt and tributylphosphane sulfide (see scheme). In contrast to other reactions of this type, they proceed under mild conditions (70 degrees C, 1 atm CO), and commercially available [Co(2)(CO)(8)] can be used without further purification.

Journal Article↗
PubMed2000

Enantiomeric determination of L- and D-lactic acid in human cerebrospinal fluid by chiral ligand exchange high-performance liquid chromatography.

Enantiomeric determination of L- and D-lactate in human cerebrospinal fluid (CSF) was achieved by HPLC on a chiral stationary phase with UV detection. Samples were submitted to a solid-phase extraction procedure using Oasis HLB Plus Extraction Cartridge and L- and D-lactate in the extract were separated by Shodex ORpac CRX-453 B column, a ligand exchange column for chiral separation, using a mobile phase containing copper (II) ion. L- and D-lactate were determined in 25 min. Intra-assay precision in CSF was 4.98% (mean 1.85 mmol/L) for L-lactate and 10.1% (mean 4.96 micromol/L) for D-lactate (n = 5). Detection limits were between 1.0 (L-lactate) and 1.5 (D-lactate) pmol. The mean values (n = 3) of analytical recovery for L- and D-lactate were 95% and 107%, respectively. The mean +/- SD of concentrations of L- and D-lactate in CSF (n = 20) were 1.52 +/- 0.54 mmol/L and 10.98 +/- 5.15 micromol/L, respectively.

Calibration↗
PubMed2000

Antibody-regulated neurotoxic function of cell-surface beta-amyloid precursor protein.

APP is a transmembrane precursor of beta-amyloid, and its mutations cause early-onset familial Alzheimer's disease. We report a toxic function of normal wild-type APP (wtAPP). Treatment of neuronal F11 cells, immortalized embryonic day 13 neurons, overexpressing wtAPP with anti-APP antibodies caused death. Death was not induced by antibody in parental F11 cells. Death by antibody occurred through cell-surface APP, not through secreted APP, in a pertussis toxin-sensitive manner and was typical apoptosis, not observed in primary astrocytes or glioma cells overexpressing wtAPP, but observed in primary cortical neurons. Cell-surface APP thus performs a toxic function as an extracellularly controllable regulator of neuronal death. This study provides a novel insight into the normal and pathological functions of cell-surface wtAPP.

Alzheimer Disease↗
PubMed2000

In vitro characterization of J-113397, a non-peptide nociceptin/orphanin FQ receptor antagonist.

The lack of availability of a selective, highly potent, competitive antagonist for the nociceptin receptor (OP4) devoid of residual agonistic activity has hampered studies in this area. We report here the in vitro pharmacological properties of the novel non-peptide OP4 antagonist, J-113397, which was recently discovered by Banyu Pharmaceutical investigators. The compound was synthesized as a racemic mixture in our laboratories. J-113397 was shown to antagonize (pA2 7.52) the nociceptin-induced inhibition of cAMP formation in cells expressing the recombinant human OP4 receptor (CHOhOP4) and to displace [125I]Tyr14nociceptin from CHOhOP4 membranes with a pKi of 8.56. It also competitively antagonized the contractile actions of nociceptin in the mouse colon (pA2 8.07) and the inhibitory effect of nociceptin in electrically stimulated preparations such as the mouse vas deferens (pA2 7.85), the guinea pig ileum (7.75), and the rat vas deferens (7.77). At high concentrations (10 microM), the compound was devoid of agonist activity in the mouse vas deferens and CHOhOP4, while it contracted the mouse colon and increased the twitch response of the rat vas deferens, and produced a naloxone-sensitive inhibition of the electrically evoked twitches in the guinea pig ileum. pA2 values for the new antagonist against deltorphin I in the mouse vas deferens (OP1 receptors), or against dermorphin in the guinea pig ileum (OP3 receptors), etorphine in the rat vas deferens (OP receptors), U69593 in the rabbit vas deferens (OP2 receptors) and endomorphin 1 in the mouse colon (OP3 receptors) were lower than 6. Taken together, these data indicate that J-113397 is a high-affinity, selective and competitive antagonist of the OP4 receptor; this novel pharmacological tool will be of great value in studies directed at evaluating the physiological roles of the nociceptin/OP4 system.

Animals↗
PubMed2000

Influence of stent design on the immediate and long-term outcome after coronary stent implantation: a comparison of sinusoidal-ring and tube stents.

To evaluate the influence of stent design on the immediate and long-term outcome after coronary stent implantation, we retrospectively reviewed 151 patients (170 lesions) who underwent coronary stent implantation. The patients were divided into two groups according to the stent design, namely, the sinusoidal-ring group (GFX stent and AVE S670 stent; 64 patients, 66 lesions) and the tube group (Multi-Link stent and NIR stent; 87 patients, 104 lesions). The indication for coronary stent implantation was only provisional and additional stenting was considered in the presence of suboptimal results (residual stenosis >30%) or of a large dissection after balloon angioplasty. Angiographically confirmed success was achieved in all patients. No major adverse cardiac events were documented in either group during the hospitalization period. There were no cases of death nor of Q-wave myocardial infarction in either group during the follow-up period. The restenosis and target lesion revascularization (TLR) rates were 24.1% and 15.3% in the sinusoidal-ring group, and 20.2% and 12.6% in the tube group. respectively. The restenosis and TLR rates were similar in both groups. In conclusion, an influence of stent design on the immediate and long-term outcome after coronary stent implantation was not observed using sinusoidal-ring and tube stents.

Aged↗
PubMed2000

Structural requirements for determining the substrate affinity of peptide transporters PEPT1 and PEPT2.

Peptide transporters PEPT1 and PEPT2 transport numerous compounds including small peptides, peptide-like drugs and nonpeptidic compounds such as valacyclovir. PEPT1 and PEPT2 show low and high affinity for most substrates, respectively, but beta-lactam antibiotics without an alpha-amino group are the only known substrates that prefer PEPT1 to PEPT2. The aim of this study was to compare the recognition and affinity of various substrates between rat PEPT1 and rat PEPT2, and to determine the structural requirements influencing the substrate affinity. [14C]Glycylsarcosine uptake by PEPT1- or PEPT2-expressing transfectant was inhibited by di- and tripeptides, but not by amino acids, tetrapeptides or most cyclic dipeptides. All dipeptides and tripeptides examined showed more potent inhibition of [14C]glycylsarcosine uptake via PEPT2 than via PEPT1, irrespective of their charge and structure. Modification of the alpha-amino group of dipeptides reduced their substrate affinity to both transporters, as compared to unmodified dipeptides, but these dipeptides still showed potent inhibitory effects on PEPT2. Among the nonpeptidic substrates tested, only the eight-amino-octanoic acid displayed stronger inhibition of [14C]glycylsarcosine uptake in PEPT1 than in PEPT2. These findings suggest that alpha- or beta-amino carbonyl function is the key structure responsible for the higher affinity for PEPT2 than for PEPT1.

Animals↗
PubMed2000

Identification of high-risk breast cancer patients from genetic changes of their tumors.

To identify the genetic prognostic markers for breast cancer, we analyzed loss of heterozygosity (LOH) at 11p, 16q, 17p, 17q, and 18q, as well as amplification of the ERBB2, INT2, and MYC genes, in 131 patients with breast carcinoma, 49 of whom had lymph node involvement, but none of whom had distant metastases. Among the several chromosome arms tested, LOH at 17q was correlated with lymph node metastasis. Amplification of the ERBB2, MYC, and INT2 genes was found more frequently in tumors from patients with lymph node metastases than in tumors from those without lymph node metastases. Univariate analysis demonstrated that LOH at 17q and INT2 amplification were factors influencing disease-free survival (DFS). A multivariate analysis was performed on 89 tumors that were able to be evaluated for both LOH at 17q and INT2 amplification, and the results showed that patients who had tumors with these genetic changes were more likely to have a poor prognosis. The findings of this study suggest that investigating genetic changes, in addition to conventional clinicopathologic factors, may contribute to defining groups of breast cancer patients with differences in prognosis.

Blotting, Southern↗
PubMed2000

Holding characteristics of planar objects suspended by near-field acoustic levitation

The authors have found the acoustic levitation phenomenon where planar objects of 10 kg weight can be levitated near a vibration surface. This phenomenon has been studied for non-contact transportation. A circular planar object can be suspended without contacting a circular vibration plate. We have studied the holding force which acts horizontally on the levitated objects. The horizontal position of the object is stabilized by this force. In this paper, we discuss the effect of the radius of a levitated object, levitation distance, displacement amplitude of the vibration plate and the vibration mode on the suspending force.

Journal Article↗