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M Ikeda

Publications and source records attributed to M Ikeda.

At least 523 records · Page 29Linked to original sources
PubMed1998

Construction of a specific and sensitive sandwich enzyme immunoassay for 20 kDa human growth hormone.

Twenty kilodalton human growth hormone (20K-hGH) is a naturally occurring isoform lacking amino acid residues 32-46 of 22K-hGH. Due to this structural similarity to 22K-hGH, no one has constructed a specific and sensitive assay system for 20K-hGH, which can be used for measuring physiological concentration of this isoform in the circulation. To construct such a specific assay system, we have generated polyclonal antibodies (pAb) and monoclonal antibodies (mAbs) against recombinant 20K-hGH. Binding characteristics to 20K-, 22K-hGH and monkey GH (mGH) of these five mAbs, designated A23, B13, C02, D05, and D14, were analyzed by enzyme immunoassays (EIAs) and surface plasmon resonance analysis. Only one of them, the mAb D05, does not crossreact with 22K-hGH. It was also observed that mAb B13 does not crossreact with mGH, although the later is 96% homologous to hGH. Using these antibodies we have established several sandwich EIA systems for circulating 20K-hGH. The combination of A23 as a solid-phase antibody and B13 as a labeled antibody permitted both high sensitivity to 20K-hGH (< 0.1 ng/ml) and low cross-reactivities with 22K-hGH (< 2%), mGH (< 0.3%) and rat GH (< 0.1%). The clearances of administered 20K-hGH were determined by this combination in both rats and monkeys. In the assay of physiologically circulating 20K-hGH in humans, the combination of D05 and affinity-purified anti-20K-hGH pAb showed the highest sensitivity to 20K-hGH (< 10 pg/ml) and substantially no cross-reactivity with 22K-hGH (< 0.1%). The plasma 20K-hGH concentration in healthy female subjects was determined by this combination. The assay systems constructed here enables us to directly measure circulating 20K-hGH in physiological condition with no interference of 22K-hGH for the first time.

Adult↗
PubMed1998

Constitutive and induced IL-18 receptor expression by various peripheral blood cell subsets as determined by anti-hIL-18R monoclonal antibody.

Interleukin-18 (IL-18) was identified as a molecule that induces IFN-gamma production and enhances NK cell cytotoxicity. Characterization of the receptor for human IL-18 (hIL-18R) is important for investigating the physiological role of IL-18 in nature. In the present study, we describe a monoclonal antibody (mAb) against hIL-18R (mAb No. 117-10C). This mAb inhibited the binding of 125I-labeled hIL-18 to IL-18R-expressing L428 cells. This mAb also neutralized hIL-18-induced T helper 1 type cytokine (IFN-gamma and GM-CSF) production by Con A-stimulated PBMC. PBMC were examined for the expression of IL-18R by two-color flow cytometry. Most CD19(+) B cells and a percentage of CD8(+) T cells were found to constitutively express IL-18R. Treatment of PBMC with IL-12 preferentially induced IL-18R expression on CD56(+) NK cells regardless of costimulation with mitogen. IL-18R expression on CD4(+) T cells was induced weakly by IL-12 treatment and moderately by PHA stimulation. However, neither could IL-12 treatment nor PHA stimulation induce IL-18R expression on CD8(+) T cells. Costimulation with both IL-12 and PHA was necessary for optimal IL-18R expression on CD8(+) T cells as well as on CD56(+) NK cells, CD4(+) T cells, and CD19(+) B cells. These results support the growing number of reports showing that IL-18 has modulatory effects on T, B, and NK cells.

Animals↗
PubMed1998

Activated endothelial cells induce apoptosis in leukemic cells by endothelial interleukin-8.

Tumor cells are eradicated by several systems, including Fas ligand-Fas and tumor necrosis factor (TNF)-tumor necrosis factor receptor (TNFR). In the previous study, we purified an apoptosis-inducing factor (AIF) to homogeneity from a medium conditioned by PDBu-treated HL-60 cells. N-terminal sequence analysis showed that AIF is identical to endothelial interleukin-8 (IL-8). A novel apoptosis system, in which endothelial cells participate via endothelial IL-8 release, is identified here. Human umbilical vein cells (VE cells) produce and secrete IL-8 by stimulation of IL-1alpha and TNF-alpha. Endothelial IL-8, which is secreted from VE cells by stimulation of IL-1alpha and TNF-alpha , induces apoptosis in myelogenous leukemia cell line K562 cells. Monocyte-derived IL-8 could not induce apoptosis in K562 cells. Moreover, interaction between VE cells and K562 cells induces the release of endothelial IL-8 from VE cells, and the attached K562 cells undergo apoptosis. Moreover, interactions between VE cell and other cell lines, such as HL-60, U937, Jurkat, and Daudi, induce the secretion of endothelial IL-8 and the induction of apoptosis in cell lines. Endothelial IL-8 significantly inhibits tumor growth of intraperitoneal and subcutaneous tumor mass of K562 cells and induces apoptosis in their cells in vivo. Endothelial IL-8 plays an important role in apoptosis involving endothelial cells, which may provide us with a new therapy for hematological malignancies.

Animals↗
PubMed1998

Regulation of cell growth-dependent expression of mammalian CDC6 gene by the cell cycle transcription factor E2F.

CDC6 of Saccharomyces cerevisiae regulates the DNA replication initiation through the origin recognition complex (ORC). Identification of a human homolog of the CDC6 gene (HsCdc6) suggests a universal role of the gene product in DNA replication. Expression of HsCdc6 is growth-regulated. We investigated the molecular basis of growth-regulated expression of mammalian Cdc6. The promoter activity of isolated HsCdc6 upstream region was activated at late G1 and G1/S boundary in the cell cycle of rat embryonic fibroblast REF52 cells by the addition of serum. The isolated promoter was activated by exogenous expression of E2F without serum stimulation. However a mutant promoter lacking the E2F recognition sites failed to respond to serum stimulation and exogenous expression of E2F. Expression of endogenous Cdc6 was induced by exogenous expression of E2F. Therefore, we concluded that the growth-regulated expression of mammalian Cdc6 was mediated by E2F. Moreover, we demonstrated that exogenous overexpression of either HsCdc6 or HsOrc1 failed to induce DNA synthesis unlike overexpression of E2F1, even though E2F1 induced both Cdc6 and Orc1, suggesting that E2F may regulate the expression of another gene(s), besides Cdc6 and Orc1, required for induction of cellular DNA synthesis in mammalian cells.

Animals↗
PubMed1998

Lead and cadmium contents in cereals and pulses in north-eastern China.

It is known that, unlike Japanese, Koreans or southern Chinese who depend on rice as a major source of energy for daily life, people in north-eastern China rely not only on rice, but on wheat and other cereals and to a lesser extent also on pulses. Cereal and pulse samples were collected from open markets in north-eastern China, and analyzed by inductively-coupled plasma spectrometry (ICP-MS) for two potentially hazardous heavy metals--lead (Pb) and cadmium (Cd). The average Pb level in cereals (31.3 ng Pb/g as a geometric mean) and that of pulses (25.7 ng Pb/g) were similar to each other with no significant difference. Among the cereals, Pb contents were higher in foxtail millet (54.3 ng/g) and lower in maize (35.4 ng Pb/g; grain and flour in combination), wheat flour (28.8 ng Pb/g) and rice flour (22.7 ng Pb/g). Lead levels in two important types of pulses, kidney bean and soybean (24.6 and 30.8 ng Pb/g, respectively), were comparable to the levels in rice and wheat. In contrast, Cd levels were substantially higher in pulses (55.7 ng Cd/g) than in cereals (9.2 ng Cd/g), and among the pulses, Cd in soybean (55.7 ng Cd/g) was significantly higher than that in kidney bean (23.8 ng Cd/g). The possible public health implication of the Pb and Cd levels, especially the high Pb level in foxtail millet (54.3 ng Pb/g) and the high Cd level in soybean (73.5 ng Cd/g), is discussed.

Cadmium↗
PubMed1998

Circadian oscillation of BMAL1, a partner of a mammalian clock gene Clock, in rat suprachiasmatic nucleus.

A superfamily gene which encodes a bHLH (basic helix-loop-helix)/PAS transcription factor, BMAL1, was cloned and sequenced from rat cDNA. A robust circadian rhythm of rat BMAL1 expression was detected by in situ hybridization in the suprachiasmatic nucleus (SCN), the site of the circadian clock, with the highest level at the subjective night. Less prominent and completely reversed circadian rhythms of rBMAL1 mRNA were observed in the piriform and parietal cortices. The hybridization signals of rBMAL1 mRNA were also detected in the olfactory bulb, hippocampus, and cerebellum. Since the product of rBMAL1 was recently demonstrated to dimerize with the protein of a mammalian clock gene, Clock, and the protein complex was shown to bind the E Box in the promoter region of mPer1 (a mouse homologue to Drosophila clock gene, Per), rBMAL1 possibly plays a critical role in the clock mechanism generating the circadian oscillation in rats.

ARNTL Transcription Factors↗
PubMed1998

Abundances of ethylene oxide and acetaldehyde in hot molecular cloud cores.

We have searched for millimetre-wave line emission from ethylene oxide (c-C2H4O) and its structural isomer acetaldehyde (CH3CHO) in 11 molecular clouds using SEST. Ethylene oxide and acetaldehyde were detected through multiple lines in the hot cores NGC 6334F, G327.3-0.6, G31.41+0.31, and G34.3+0.2. Acetaldehyde was also detected towards G10.47+0.03, G322.2+0.6, and Orion 3'N, and one ethylene oxide line was tentatively detected in G10.47+0.03. Column densities and rotational excitation temperatures were derived using a procedure which fits the observed line intensifies by finding the minimum chi 2-value. The resulting rotational excitation temperatures of ethylene oxide and acetaldehyde are in the range 16-38 K, indicating that these species are excited in the outer, cooler parts of the hot cores or that the excitation is significantly subthermal. For an assumed source size of 20", the deduced column densities are (0.6-1)x10(14) cm-2 for ethylene oxide and (2-5)x10(14) cm-2 for acetaldehyde. The fractional abundances with respect to H2 are X[c-C2H4O]=(2-6)xl0(-10), and X[CH3CHO]=(0.8-3)x10(-9). The ratio X[CH3CHO]/X[c-C2H4O] varies between 2.6 (NGC 6334F) and 8.5 (G327.3-0.6). We also detected and analysed multiple transitions of CH3OH, CH3OCH3, C2H5OH, and HCOOH. The chemical, and possibly evolutionary, states of NGC 6334F, G327.3-0.6, G31.41+0.31, and G34.3+0.2 seem to be very similar.

Acetaldehyde↗
PubMed1998

Thyroid hormone response elements differentially modulate the interactions of thyroid hormone receptors with two receptor binding domains in the steroid receptor coactivator-1.

Ligand-dependent transcriptional activation by nuclear receptors is mediated by interactions with coactivators. Recently, a consensus interaction motif (LXXLL) has been identified in a number of coactivators such as steroid receptor coactivator-1 (SRC-1). SRC-1 contains three such motifs in the central (nuclear receptor binding domain-1, NBD-1) and a single one in the C-terminal (NBD-2) regions. To define the nature and role of the two NBDs in SRC-1, interaction studies between the two NBDs and thyroid hormone receptor (TR) were performed. Although NBD-1 and NBD-2 showed similar ligand- and AF-2-dependent interactions with TR in solution, these two NBDs possessed distinct interaction properties with TR when TR is bound to a thyroid hormone-response element (TRE). Both in vitro and in vivo interaction studies demonstrate that NBD-1, but not NBD-2, exhibits ligand-dependent interaction with TR in the presence of TREs. In addition, a natural isoform of SRC-1, SRC-1E, which lacks NBD-2, preserved TR as well as progesterone receptor-mediated coactivator function on reporter gene expression. Finally, we found that NBD-1 failed to interact with a TR and retinoid X receptor heterodimer complex on a transcriptionally inactive direct repeat +4 TRE in electrophoretic mobility shift assays. These observations indicate that DNA-induced, as well as ligand-induced, conformational change(s) of TR may influence the nature of its binding to SRC-1, and that the two NBDs of SRC-1 may play different roles to regulate ligand-dependent transactivation of TRs.

Animals↗
PubMed1998

Evidence for an Alzheimer disease susceptibility locus on chromosome 12 and for further locus heterogeneity.

CONTEXT: Alzheimer disease (AD) susceptibility genes have been identified on chromosomes 1, 14, 19, and 21, and a recent study has suggested a locus on chromosome 12. OBJECTIVE: To confirm or refute the existence of a familial AD susceptibility locus on chromosome 12 in an independent sample of familial AD cases. DESIGN: Retrospective cohort study. DNA data for 6 chromosome 12 genetic markers were evaluated using parametric lod score and nonparametric linkage methods and linkage heterogeneity tests. The latter include the admixture test of homogeneity in the total group of families and the predivided sample test in families stratified by the presence or absence of an apolipoprotein E (APOE) epsilon4 allele among affected members. Parametric analyses were repeated assuming autosomal dominant inheritance of AD and either age- and sex-dependent penetrance or zero penetrance for the analysis of unaffected relatives. SETTING: Clinical populations in the continental United States, Canada, Argentina, and Italy. PATIENTS: Fifty-three white families composed of multiple members affected with AD, from whom DNA samples were obtained from 173 patients with AD whose conditions were diagnosed using established criteria and from 146 nondemented relatives. MAIN OUTCOME MEASURE: Presence of an APOE epsilon4 allele among affected family members. RESULTS: Using parametric methods, no evidence for linkage to the region spanned by the chromosome 12 markers could be detected if familial AD is assumed to arise from the same genetic locus in all 53 families. However, significant evidence for linkage was detected in the presence of locus heterogeneity using the admixture test (odds ratio, 15, 135:1). The estimated proportion of linked families within the 53 families examined varied between 0.40 and 0.65, depending on the genetic model assumed and APOE status. The precise location of the AD gene could not be determined, but includes the entire region suggested previously. Nonparametric linkage analysis confirmed linkage to chromosome 12 with the strongest evidence at D12S96 (P<.001). CONCLUSIONS: Our data provide independent confirmation of the existence of an AD susceptibility locus on chromosome 12 and suggest the existence of AD susceptibility genes on other chromosomes. Screening a larger set of families with additional chromosome markers will be necessary for identifying the chromosome 12 AD gene.

Adult↗
PubMed1998

Facilitation by endogenous acetylcholine and nitric oxide of luminal serotonin release from the guinea-pig colon.

The present study was designed to determine the influence of endogenous acetylcholine and nitric oxide (NO) on spontaneous luminal serotonin (5-hydroxytryptamine, 5-HT) release in the luminally perfused isolated guinea-pig proximal colon in vitro. 5-HT was determined by high-performance liquid chromatography with electro-chemical detection. The luminal outflow of 5-HT was significantly reduced by atropine (0.2 microM), hexamethonium (100 microM), the NO synthase inhibitor NG-nitro-L-arginine (L-NNA, 10 microM) and the NO-trapping agent 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (carboxy-PTIO, 30 microM). Addition of excess L-arginine (300 microM) reversed the inhibitory effect of L-NNA on the 5-HT outflow. Physostigmine (1 microM) caused a great increase (atropine-sensitive) in 5-HT outflow. The enhancing action of physostigmine on 5-HT outflow was partially inhibited by L-NNA (100 microM) or carboxy-PTIO (30 microM), but was unaffected by the muscarinic M1 receptor antagonist pirenzepine (0.2 microM) or a muscarinic M3 receptor antagonist 4-diphenyl-acetoxy-N-methyl-piperidine methiodide (0.2 microM). These results suggest that 5-HT release from luminally perfused proximal colon of the guinea pig is stimulated via a NO pathway and cholinergic pathways which utilize muscarinic synapses and nicotinic synapses. Further, an intrinsic cholinergic-NO link appears to play a role in the stimulation of luminal 5-HT release, which may reflect the release of 5-HT from entero-chromaffin cells.

Acetylcholine↗
PubMed1998

Diagnostic value of plasma thrombin-antithrombin III complex and D-dimer concentration in patients with varicose veins for exclusion of deep-vein thrombosis.

The aim of this study was to evaluate the usefulness of determining plasma D-dimer (DD) and thrombin-antithrombin III complex (TAT) levels in the diagnostic workup for the screening of deep-venous thrombosis (DVT) among varicose vein patients. One hundred forty consecutive patients being treated for DVT or varicose veins underwent color-flow duplex scanning, and 25 patients had DVT and the remaining 115 had primary varicose veins. When DD and TAT were analyzed statistically in combination, it was determined that the combination of either positive DD (cutoff level 1.0 microg/ml) or positive TAT (cutoff level 3.0 microg/l) had a sensitivity of 100% for DVT with a specificity, positive predictive value, and negative predictive value of 79%, 51%, and 100%, respectively. This study demonstrates plasma levels of DD (less than 1.0 microg/ml) and TAT (less than 3.0 microg/l) in combination to be useful for the exclusion of DVT among patients with varicose veins. Patients with negative hematological data may safely undergo surgical treatment for varicose veins without further evaluation such as duplex scanning or contrast venography.

Antithrombin III↗
PubMed1998

Absence of association between Alzheimer disease and the -491 regulatory region polymorphism of APOE.

A novel polymorphism (-491 A/T) within the regulatory region on the apolipoprotein E gene has recently been reported to be associated with risk for Alzheimer disease (AD). To test this association in an independent data set, we have examined this polymorphism in a sample of 88 well-characterized AD cases and compared the allele frequency and genotype frequencies for this polymorphism with those observed in 112 cognitively normal subjects drawn from the same ethnic group. These results suggest that in the current data set at least, the -491 A/T polymorphism is not associated with risk for AD, but may be in partial linkage disequilibrium with the APOE epsilon2/epsilon3/epsilon4 polymorphism.

Aged↗
PubMed1998

Urban-rural comparison on cadmium exposure among general populations in Shandong Province, China.

In 1996, peripheral blood samples and 24-h food duplicate samples together with samples of wheat, rice, foxtail millet and maize were collected from 50 non-smoking women each from Jinan (a provincial capital) and Baiquan (a nearby basically self-sustaining farming village) in China. The samples were analyzed for cadmium (Cd) contents by graphite furnace atomic absorption spectrometry after wet digestion. The dietary Cd intake of the people in the city was 6.4 micrograms/day as a geometric mean (GM) and 5.9 micrograms/day for the villagers. The Cd level in blood was 0.48 and 0.29micrograms/l (as GMs) for the city and village people, respectively. Thus, Cd burden of the people in the city tended to be greater than that for those in the village. Nevertheless, the Cd burden of the Jinan citizens was lower than the values published for people in large cities in China. When Cd intake via the four cereals was compared with Cd in total food to estimate the total contribution of the four cereals (combined) in total dietary Cd intake, the cereals accounted for 60% of total dietary Cd intake among the city people and as high as 78% among the villagers. Cadmium contents in the four cereals were in a narrow range and it was considered acceptable to combine all cereals in evaluating them as dietary Cd sources.

Adult↗
PubMed1998

Leukocystatin, a new Class II cystatin expressed selectively by hematopoietic cells.

We describe a new cystatin in both mice and humans, which we termed leukocystatin. This protein has all the features of a Class II secreted inhibitory cystatin but contains lysine residues in the normally hydrophobic binding regions. As determined by cDNA library Southern blots, this cystatin is expressed selectively in hematopoietic cells, although fine details of the distribution among these cell types differ between the human and mouse mRNAs. In addition, we have determined the genomic organization of mouse leukocystatin, and we found that in contrast to most cystatins, the leukocystatin gene contains three introns. The recombinant proteins corresponding to these cystatins were expressed in Escherichia coli as N-terminal glutathione S-transferase or FLAGTM fusions, and studies showed that they inhibited papain and cathepsin L but with affinities lower than other cystatins. The unique features of leukocystatin suggests that this cystatin plays a role in immune regulation through inhibition of a unique target in the hematopoietic system.

Amino Acid Sequence↗
PubMed1998

Calcium-independent activation of extracellular signal-regulated kinases 1 and 2 by cyclic strain.

We have previously demonstrated that cyclic strain induces extracellular signal-regulated kinases 1 and 2 (ERK1/2) activation in endothelial cells (EC). The aim of this study was to investigate the effect of Ca2+ on the activation of ERK1/2. Bovine aortic EC were pretreated with a chelator of extracellular Ca2+, ethylaneglycol-bis(aminoethylether)-tetra-acetate (EGTA), a depleter of Ca2+ pools, 2,5-Di-(tert-butyl)-1,4-benzohydroquinone (BHQ), or a Ca2+ channel blocker, GdCl3, and subjected to an average 10 % strain at a rate of 60 cycles/min for 10 min. BHQ and GdCl3 did not inhibit the strain-induced ERK1/2 activation. Chelation of normal extracellular Ca2+ (1.8 mM) medium with EGTA (3 mM) acutely stimulated baseline phosphorylation and activation of ERK1/2, thereby obscuring any strain-induced activation of ERK1/2. However, in EC preincubated for 24 hours in Ca2+-free medium, elevated baseline phosphorylation was minimally activated by EGTA (200 microM) such that cyclic strain stimulated ERK1/2 in the presence or absence of BHQ. These results suggest a Ca2+ independence of the ERK1/2 signaling pathway by cyclic strain.

Animals↗
PubMed1998

Methylcobalamin amplifies melatonin-induced circadian phase shifts by facilitation of melatonin synthesis in the rat pineal gland.

Effects of methylcobalamin (methyl-B12), a putative drug for treating human circadian rhythm disorders, on the melatonin-induced circadian phase shifts were examined in the rat. An intraperitoneal injection of 1-100 microg/kg melatonin 2-h before the activity onset time (CT 10) induced phase advances of free-running activity rhythms in a dose-dependent manner (ED50=1.3 microg/kg). Injection of methyl-B12 (500 microg/kg) prior to melatonin (1 microg/kg) injection induced larger phase advances than saline preinjected controls, while the injection of methyl-B12 in combination with saline did not induce a phase advance. These results indicate amplification of melatonin-induced phase advances by methyl-B12. Pinealectomy abolished the phase alternating effect of methyl-B12, suggesting a site of action within the pineal gland. In fact, methyl-B12 significantly increased the content of melatonin in the pineal collected 2-h after activity onset (CT 14). In contrast, no difference in melatonin content was found at CT 10, indicating that the effect of methyl-B12 may be gated after the activity onset time when endogenous melatonin synthesis is known to increase. These results suggest that methyl-B12 amplifies melatonin-induced phase advances via an increase in melatonin synthesis during the early subjective night at a point downstream from the clock regulation.

Animals↗
PubMed1998

Ultraviolet radiation, but not gamma radiation or etoposide-induced DNA damage, results in the phosphorylation of the murine p53 protein at serine-389.

Polyclonal antibodies were produced and purified that selectively react with a p53 epitope containing the murine phosphoserine-389 or the human phosphoserine-392 residue, but not the unphosphorylated epitope. These antibodies, termed alpha-392, were employed to demonstrate that the phosphorylation of this serine-389 residue in the p53 protein occurs in vivo in response to ultraviolet radiation of cells containing the p53 protein. After ultraviolet radiation of cells in culture, p53 levels increase and concomitantly serine-389 is phosphorylated in these cells. By contrast, the serine-389 phosphorylation of the p53 protein was not detected by these antibodies in the increased levels of p53 protein made in response to gamma radiation or the treatment of cells with etoposide. These results demonstrate an ultraviolet responsive and specific phosphorylation site at serine-389 of the mouse or serine-392 of the human p53 protein. Previous studies have demonstrated that this phosphorylation of p53 activates the protein for specific DNA binding. This study demonstrates in vivo a unique phosphorylation site in the p53 protein that responds to a specific type of DNA damage.

Animals↗