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Biomedical subjects

M Takeuchi

Publications and source records attributed to M Takeuchi.

At least 271 records · Page 15Linked to original sources
PubMed1998

Beta-casomorphin-5 stimulates neurite outgrowth in a mouse neuroblastoma cell line (Neuro-2a).

We studied the effect of beta-casomorphin-5 (mu-acting opioid peptides derived from milk protein beta-casein) on neurite outgrowth of mouse neuroblastoma cell line, Neuro-2a. Beta-casomorphin-5 stimulated neurite outgrowth of Neuro-2a cells in a naloxone-reversible manner. The stimulating effect of beta-casomorphin-5 was observed even at picomolar concentrations. The selective mu-agonist, (D-Ala2, N-Me-Phe4, Gly5-ol)-enkephalin (DAMGO) exhibited the similar stimulating effect only at micromolar concentrations. On the other hand, (D-Pen(2,5))-enkephalin (DPDPE) (a delta-agonist), U-50,488 (a kappa-agonist), and endogenous opioid peptides, such as enkephalins and dynorphin A (1-13), showed no such stimulating effect. These results suggest that the neurite outgrowth-stimulating action of beta-casomorphin-5 may be mediated via a receptor which has mu-like characteristics and high sensitivity to beta-casomorphin-5, and that beta-casomorphins may play a role as a neurite elongation factor during the suckling period.

Animals↗
PubMed1998

Regional ventricular systolic abnormalities caused by a rudimentary chamber in patients with univentricular hearts.

Previous studies have demonstrated that regional wall motion abnormalities are common in univentricular hearts; however, the mechanism of this abnormality and its relation to hemodynamics remain unclear. The aim of this study was to document and analyze the etiology of regional wall motion abnormality and its relation to hemodynamics in univentricular hearts. Sixteen patients (age 11+/-6 years) were examined. A tagged cine magnetic resonance imaging method that superimposes "tags" on myocardium was used to assess regional systolic motion. The tags were traced from end-diastole to end-systole, and the percent regional shortening fraction was calculated as the shortening ratio. The tags were positioned on 6 segments. Normal ranges for wall motion were established from 10 normal volunteers. An asynchrony index was calculated as the SD divided by the mean regional shortening fraction to quantify asynchronous regional motion. Hemodynamic parameters were also obtained by cardiac catheterization. In patients, regional shortening fraction was significantly lower in segments adjacent to the rudimentary chamber compared with normal values in both circumferential and longitudinal directions (p <0.05 and p <0.01, respectively). The asynchrony index was much greater in patients than in controls (62+/-25 vs 27+/-10, p <0.01). The index correlated with rudimentary chamber volume and the rudimentary/main chamber volume ratio (r = 0.58, r = 0.79, respectively). Furthermore, the index correlated with end-diastolic pressure (r = 0.82). The rudimentary chamber may play an important role in causing asynchronous regional motion, and this motion may contribute to ventricular diastolic dysfunction.

Adolescent↗
PubMed1998

Synthesis and NK1 receptor antagonistic activity of (+/-)-1-acyl-3-(3,4- dichlorophenyl)-3-[2-(spiro-substituted piperidin-1'-yl)ethyl]piperidines.

(+/-)-1-Acyl-3-(3,4-dichlorophenyl)-3-[2-(spiro-substituted piperidin-1'-yl)ethyl]piperidines and their quaternary ammonium salts were prepared and evaluated for their NK1 receptor antagonistic activity. Some of these inhibited SP-induced contraction in guinea pig ileum with IC50 values at a level of 10(-9) M and showed potent inhibitory activity against selective NK1 receptor agonist-induced bronchoconstriction in guinea pigs.

Animals↗
PubMed1998

cDNA cloning and expression of bovine UDP-N-acetylglucosamine: alpha1, 3-D-mannoside beta1,4-N-acetylglucosaminyltransferase IV.

UDP-N-acetylglucosamine:alpha1,3-D-mannoside beta1, 4-N-acetylglucosaminyltransferase (GnT-IV) is one of the essential enzymes in the production of tri- and tetra-antennary Asn-linked sugar chains. Recently, we have successfully purified GnT-IV from bovine small intestine. Based on the partial amino acid sequence of the purified bovine GnT-IV enzyme, its cDNA has been cloned from bovine small intestine. The open reading frame is 1,605 base pairs long, and this sequence produced GnT-IV activity on transient expression in COS-7 cells. Although the deduced amino acid sequence does not have any significant homology with other known N-acetylglucosaminyltransferases (GnTs), the hydrophobicity profile showed a typical type II transmembrane protein structure, which is common to many glycosyltransferases. N-terminal amino acid sequencing of the purified GnT-IV revealed that 92 amino acids, including a transmembrane region, were truncated during purification. Of the three potential N-glycosylation sites Asn-458 was actually glycosylated in the purified enzyme, although this N-glycosylation site could be abolished without any reduction in GnT-IV activity. Serial deletions at both the N and C termini proved that the catalytic domain of GnT-IV is located in the central region of the enzyme. The GnT-IV mRNA level correlated with enzymatic activity in the various bovine tissues tested.

Amino Acid Sequence↗
PubMed1998

Trace analysis of tributyltin and triphenyltin compounds in sea water by gas chromatography-negative ion chemical ionization mass spectrometry.

An analytical gas chromatography-mass spectrometry (GC-MS) method using negative ion chemical ionization (NICI) has been investigated for the determination of trace tributyltin (TBT) and triphenyltin (TPhT) compounds in sea water. TBT and TPhT were extracted from samples as chloride under the acidic condition of HCl. Doping of the GC system with a dilute HBr-methanolic solution resulted in direct detection of the chlorides of TBT, TPhT and tripentyltin (TPenT, internal standard). As the result of HBr doping, a sharp peak of the respective organotin bromides appeared: during GC analysis, halogen exchange from the chloride to the bromide occurred. NICI-MS was highly selective and sensitive for the detection of TBT. TPhT and TPenT bromides. In the selected ion monitoring mode of NICI-MS, the minimum detectable amounts defined as the signal equal to three times the standard deviation (3 sigma) of the baseline noise were 20 and 25 pg ml-1 for TBT and TPhT, respectively. These amounts are approximately 250-400 times better than those in electron impact mode. The combination of GC using an apolar capillary column doped with a dilute HBr-methanolic solution and NICI-MS made it possible to determine TBT and TPhT at less than the ng l-1 level in sea water.

Gas Chromatography-Mass Spectrometry↗
PubMed1998

Interleukin-18 activates the IRAK-TRAF6 pathway in mouse EL-4 cells.

The pleiotropic biological activities of interleukin-18 (IL-18) are mediated by IL-18 receptor (IL-18R). When the ligand binds to the IL-18R, IL-18R initiates a signaling cascade that results in the activation of nuclear factor kappa B (NF-kappa B). When mouse EL-4 cells were exposed to IL-18, IL-1 receptor-associated kinase (IRAK) was recruited to IL-18R and was phosphorylated. In addition, tumor necrosis factor receptor-associated factor-6 (TRAF6) was associated with IRAK. Therefore, we concluded that IL-18/IL-18R-mediated signaling may share the IRAK/TRAF6 pathway through NF-kappa B activation with the IL-1/IL-1 receptor system.

Animals↗
PubMed1998

TGF-beta promotes immune deviation by altering accessory signals of antigen-presenting cells.

Macrophages incubated with OVA in the presence of TGF-beta2 induce immune deviation in vivo (impaired delayed hypersensitivity and IgG2a Ab production) when injected into naive, syngeneic mice. OVA-specific TCR transgenic naive T cells (DO11.10 T cells) produce Th1-type cytokines when stimulated in vitro with OVA-pulsed peritoneal exudate cells (PEC), but if PEC are first treated with TGF-beta2 and then pulsed with OVA, the T cells secrete Th2-type cytokines instead. In this study, we investigated the mechanisms that are involved in the modified Ag-presenting functions of macrophages by TGF-beta2 pretreatment. We have found that: 1) TGF-beta2 impaired the capacity of PEC to produce IL-12 and to express CD40; 2) reduced CD40 expression on TGF-beta2-treated PEC impaired IL-12 production when the cells were cocultured with DO11.10 T cells; 3) the failure of TGF-beta2-treated PEC to stimulate DO11.10 T cells to secrete IFN-gamma was due to their impaired IL-12 production. From these results, we conclude that TGF-beta2 treatment impairs the ability of macrophages to produce IL-12 and to express CD40. As a consequence, TGF-beta2-treated PEC fail to promote development of pT cells toward the Th1 phenotype.

Animals↗
PubMed1998

Molecular cloning and characterization of rat lin-10.

In Caenorhabditis elegans, the vulval induction is mediated by tyrosine kinase receptor/Ras signal transduction pathway composed of the lin-3, let-23, and let-60 products. In addition to these gene products, the lin-2, lin-7, and lin-10 products are also implicated in this pathway. Lin-2 encodes a MAGUK and lin-7 encodes a small protein with one PDZ domain. The lin-10 product has no homology to known proteins. Here, we have cloned a rat homologue of the lin-10 product and characterized it. Rat lin-10 is ubiquitously expressed in various rat tissues and distributed in both the cytosol and membrane fractions. In brain, however, rat lin-10 is distributed only in the membrane fraction and enriched in the synaptic plasma membrane and postsynaptic density fractions. These results suggest that rat lin-10 is involved at least in synaptic functions in brain.

Animals↗
PubMed1998

Telomerase activity in hepatocellular carcinoma and adjacent liver tissues.

BACKGROUND AND OBJECTIVES: Activation of telomerase and stabilization of telomeres are considered necessary for immortalization of tumor cells. Telomerase activity was analyzed in 69 hepatocellular carcinomas and adjacent chronic liver disease tissues. The telomerase activity level was examined in relation to clinicopathologic features. METHODS: Telomerase activity was determined by a telomeric repeat amplification protocol. Immature and mature leukocytes were removed from homogenized tissue of adjacent livers using anti-CD45 and anti-CD15 monoclonal antibody-coated magnetic beads. RESULTS: Telomerase activity was detected in hepatocellular carcinomas and leukocytes, but not in liver cells from adjacent chronic liver disease tissues after the separation of leukocytes. All hepatocellular carcinomas displayed telomerase activity, and the activity level correlated with the degree of differentiation (P=0.021) and patient survival (P=0.039). CONCLUSIONS: These results indicate that activation of telomerase may be required as a critical step in hepatocarcinogenesis and tumor development, and detection of telomerase activity with removal of contaminating leukocytes may be useful in the characterization or prognostication of hepatocellular carcinoma.

Adult↗
PubMed1998

Suppression of spontaneous uveoretinitis development by non-immunopathogenic peptide immunization.

BALB/c nude mice which are grafted with thymus tissue from fetal F344 rats beneath the renal capsule (hereafter referred to as TG nude mice) spontaneously develop uveoretinitis as well as other organ-localized autoimmune diseases. Active immunization with an interphotoreceptor retinoid-binding protein (IRBP)-derived peptide, amino acids 518-529 (P518-529), induced rapid development and high incidence of uveoretinitis, whereas immunization with another amino acid fragment, 1182-1194 (P1182-1194), inhibited the disease process. P1182-1194- or P518-529-specific T cell lines were established from TG nude mice. Although both were of CD4+ type, P518-529-specific T cells expressed Vbeta8 TCR while Vbeta6 expression was evident in the P1182-1194-specific cells. P518-529-specific T cells produced IL-2 and IFN-gamma, but not IL-4 or IL-10, whereas P1182-1194-specific T cells produced IL-4 and IL-10, but not IL-2 or IFN-gamma Adoptive transfer of these peptide-specific T cells into naive BALB/c nude mice resulted in development of uveoretinitis only in the P518-529 case. Furthermore, mice receiving both T cell types simultaneously did not exhibit uveoretinitis. The results indicate that the amino acid fragment of IRBP, P518-529, is uveitogenic and immunogenic in TG nude mice and induces Th1-type T cells related to uveoretinitis, whereas the amino acid fragment 1182-1194 is immunogenic but not uveitogenic, inducing Th2-type T cells which are involved in inhibition of this pathological response in TG nude mice.

Adoptive Transfer↗
PubMed1998

Drug susceptibility of PCA in WBB6F1-W/Wv mice.

Our previous study revealed that passive cutaneous anaphylaxis (PCA) can be produced in congenitally mast cell-deficient WBB6F1-W/Wv (abbreviated as W/Wv) mice on sensitization with undiluted or slightly diluted allogeneic and xenogeneic antisera but not on sensitization with allogeneic monoclonal immunoglobulin (Ig)E and IgG1 antibodies regardless of the antibody concentration [1]. In view of these findings, the present study was conducted to characterize PCA in this strain from its drug susceptibilities using mast cell-bearing WBB6F1-(+)/+ (abbreviated as +/+) and B6D2F1 mice as references. PCA in W/Wv mice mediated by a low dilution (1:4) of hyperimmune serum to bovine serum albumin of the B6D2F1 mouse origin was markedly suppressed by CV-6209, an antagonist of platelet-activating factor (PAF), but not by antihistamines such as cyproheptadine and oxatomide. In contrast, PCA in +/+ and B6D2F1 mice mediated by a high dilution (1:128) of the anti-serum (virtually by IgG1 antibody) was nearly completely suppressed by antihistamines but not by CV-6209. A remarkable difference between PCA in W/Wv and reference mice was also observed in the susceptibility to monoclonal anti-mouse granulocyte (Gr-1) antibody: PCA in W/Wv mice was potently suppressed by the 1- to 3-day pretreatment with this antibody but that in references was not at all. Putting these present results together with the previous finding that anti-granulocyte antibody greatly reduces circulatory Gr-1+ leukocytes, 1 to 3 days after the treatment [2], it is highly probable that PCA in W/Wv mice mediated by some antibody isotypes other than IgE and IgG1 is produced by PAF mainly released from Gr-1+ cells, while IgG1 antibody-mediated PCA in mast cell-bearing reference mice is evoked by histamine derived from mast cells. PCA homologous to that in W/Wv mice could also be produced in the reference mice on sensitization with undiluted or slightly diluted antiserum, when generalized blueing due to excess IgG1 antibody was removed by the oxatomide treatment before the antigen challenge.

Animals↗
PubMed1998

Involvement of Fas in the apoptosis of mouse germ cells induced by experimental cryptorchidism.

The role of Fas in the apoptosis of testicular germ cells was investigated in BALB/c mice and Fas-deficient lpr/lpr mice. Spontaneous apoptosis of germ cells was observed in the testes of 40-day-old BALB/c mice, and experimentally induced cryptorchidism increased this apoptosis to such an extent that there was a decrease in the weight of the testis. Flow cytometry and immunohistochemistry using a Fas-specific monoclonal antibody demonstrated expression of Fas on germ cells including spermatogonia, spermatocytes, and spermatids. Furthermore, analysis by flow cytometry suggested that Fas expression on germ cells was increased following cryptorchidism. However, spontaneous and cryptorchidism-induced apoptosis of germ cells were also observed in 40-day-old Fas-deficient lpr/lpr mice. Moreover, testis weight also decreased following cryptorchidism in the mutant mice. The present results may indicate that the expression of Fas on germ cells does not correlate with spontaneous apoptosis or apoptosis induced by cryptorchidism. However, on the contrary, this study shows that Fas are partly involved in cryptorchidism-induced apoptosis, because the decrease in testis weight of lpr/lpr mice was less than that in BALB/c mice.

Animals↗
PubMed1998

Construction of a low-serine-type-carboxypeptidase-producing mutant of Aspergillus oryzae by the expression of antisense RNA and its use as a host for heterologous protein secretion.

Using an antisense control strategy, we isolated an Aspergillus oryzae mutant that produced low levels of carboxypeptidases (CPases). The mutant TFC-1 expressed the antisense RNA of the structural gene of CPase O and showed about 30% of the CPase activity in the parent strain. Gel filtration analysis indicated that this mutant decreased the CPase activities not only of CPase O but also of CPase O-1 and O-2. This result indicated that the antisense RNA was able to control the expression of the CPase genes as a group. Using the mutant as a heterologous protein expression host that produced the low levels of CPases, a stable and higher level of lysozyme expression could be obtained compared with the wild-type. In vitro proteolytic degradation assay also demonstrated that human lysozyme was degraded by purified CPase O.

Aspergillus oryzae↗
PubMed1998

Action of serine carboxypeptidase from paecilomyces carneus on oligopeptides containing carboxy-terminally amidated peptides

Paecilomyces carneus carboxypeptidase sequentially liberated amino acids from the carboxy-terminus of neurotensin, angiotensin I, bradykinin, and delta sleep-inducing peptide, indicating that the sequential hydrolysis of peptides was limited by the occurrence of intermediates with the structure of -Gly-X (X = L-amino acid), -Pro-X, -X-Gly, and -X-Pro. The enzyme had carboxyamidase and/or amidase activities for the carboxy-terminally amidated peptides. The enzyme essentially acted as a carboxyamidase for the long carboxy-terminally amidated peptides; an amidase became dominant for the substrates in the presence of bulky amino acids such as Arg, Met, Leu, and Phe in the penultimate (P1) and P2 positions, corresponding with the S1 and S2 sites of the enzyme, and the P3 position of carboxy-terminally amidated peptides played a significant role in the action as a carboxyamidase or a amidase.

Journal Article↗
PubMed1998

Apoptosis of photoreceptor cells in ornithine-induced retinopathy.

BACKGROUND: The intravitreal injection of ornithine produces selective damage to the retinal pigment epithelium (RPE) and results in a loss of RPE, choriocapillaris and photoreceptor cells. To elucidate the mechanism of secondary retinal atrophy, we investigated the presence of apoptotic cells in a rat model of ornithine-induced retinopathy. METHODS: At 6 and 12 h and 1, 2, 4, 7, 14 and 28 days after an intravitreal injection of L-ornithine hydrochloride in rat eyes, we removed the eyes and subjected them to histopathological examination. We detected apoptotic cells by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate digoxigenin nick end labeling (TUNEL) assay, which stains the 3'-OH ends of fragmented DNA. We used electron microscopy to detect the apoptotic cells morphologically. RESULTS: RPE cells were selectively damaged immediately after ornithine administration. TUNEL-positive photoreceptor cells appeared exclusively in the photoreceptor cell layer 12 h after ornithine administration. The number of TUNEL-positive cells increased throughout the 2 days following the injection, then decreased markedly. TUNEL-positive cells remained until 28 days, when the photoreceptor cells had disappeared. The ganglion cell layer, inner nuclear layer and damaged RPE cells were negative for TUNEL staining during all stages. The electron microscopic study also revealed the pyknotic nuclei of apoptotic photoreceptor cells. CONCLUSION: An intravitreal injection of ornithine caused primary damage to the RPE, and subsequently some of the photoreceptor cells revealed apoptosis by TUNEL assay. These findings suggest the dysfunction of the RPE causes photoreceptor cell death according to the intrinsic program of an apoptotic mechanism.

Animals↗
PubMed1998

Sustained induction of hepatocyte growth factor by sensitization with freeze-thawed hepatic tissue.

Hepatocyte growth factor (HGF) is a mitogen for hepatocytes, and has therapeutic potential for fibrotic/cirrhotic liver. Therefore, the induction of HGF in vivo is considered to be useful in the treatment of liver dysfunction caused by cirrhosis, chronic hepatitis, or extensive surgical resection. In this study, we examined the sustained induction of HGF by inoculation of freeze-thawed hepatic tissue (FTHT). Serum from rats inoculated with FTHT increased [3H]thymidine incorporation i.e., increased DNA synthesis, in primary cultured rat hepatocytes. The DNA synthesis was significantly promoted by the addition of the FTHT-sensitized serum, while this DNA synthesis was inhibited by neutralizing anti-rat HGF antibody. The concentration of HGF in the FTHT-sensitized serum was increased by day 3 after the inoculation. The time of HGF induction was dependent on the inoculated volume of FTHT, but peaks of HGF concentration were found on day 5 with different volumes of FTHT. Injurins, inducers of HGF, were also induced in the FTHT-sensitized rats, with their peak levels on day 3. The FTHT inoculated tissue showed inflammatory cell infiltration, which was gradually absorbed, and had completely disappeared by day 14 after the inoculation. Although mild inflammatory cell infiltration was observed in non-freeze-thawed inoculated hepatic tissue (NFHT) a tight capsule formed around the NFHT, and was scarcely phagocytized on day 14. These results suggest that FTHT inoculation induces HGF sustainedly through the increased synthesis of injurins, and that freeze-thawed tissue, which is easily phagocytized, is important for the sustained induction of HGF.

Animals↗