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H Itoh

Publications and source records attributed to H Itoh.

At least 775 records · Page 43Linked to original sources
PubMed1994

Sequencing of cDNAs encoding alpha 1-microglobulin/bikunin of Mongolian gerbil and Syrian golden hamster in comparison with man and other species.

Complementary DNAs (cDNAs) encoding alpha 1-microglobulin (alpha 1mG)/bikunin, also known as inter-alpha-inhibitor (I alpha I) light chain, were cloned from liver extracts of the Mongolian gerbil, Meriones unguiculatus, and the Syrian golden hamster, Mesocricetus auratus, by reverse transcription-polymerase chain reaction and rapid amplification of cDNA ends methods. From the deduced amino-acid sequences of alpha 1mG/bikunin of gerbil and hamster, the basic molecular structure of the proteins seemed to be well-conserved. However, near the proposed sequence of proteinase inhibitory sites of two Kunitz domains in the bikunin part, variable regions composed of three amino acids each were observed between species, including rodents. Since the second half of bikunin is genetically identical with the mast cell proteinase inhibitor, trypstatin, the bikunin of each animal may have distinct inhibitory activity against mast cell proteinases.

Alpha-Globulins↗
PubMed1994

Molecular cloning and chromosomal assignment of the mouse C-type natriuretic peptide (CNP) gene (Nppc): comparison with the human CNP gene (NPPC).

The mouse C-type natriuretic peptide (CNP) genomic fragment was isolated from a mouse genomic DNA library. The mouse CNP gene is composed of at least two exons and one intron. The 5'-flanking region contains an array of cis-acting regulatory elements and a dinucleotide CA repeat (microsatellite). Analysis of the deduced amino acid sequences revealed that mouse preproCNP is a 126-amino-acid peptide and that its C-terminal 22-residue peptide preceded by Lys-Lys is identical to porcine, rat, and human CNPs. On the basis of the polymerase chain reaction-analyzed microsatellite length polymorphisms among recombinant inbred strains of mice, the CNP gene (Nppc) was assigned to mouse chromosome 1. Furthermore, the human CNP 5'-flanking region was extended for sequencing, and comparison of the mouse and human CNP genomic sequences revealed regions of conservation and diversity. Using somatic hybrid cell methodology, the CNP gene (NPPC) was assigned to human chromosome 2. The present study has added another locus to the conserved syntenic group in mice and humans.

Amino Acid Sequence↗
PubMed1994

Natriuretic peptide clearance receptor is transcriptionally down-regulated by beta 2-adrenergic stimulation in vascular smooth muscle cells.

Three natriuretic peptide receptors (the ANP-A, ANP-B, and clearance (C) receptors) have been reported. The regulation of these receptors by catecholamines was examined in cultured rat vascular smooth muscle cells. Treatment with norepinephrine decreased the maximum 125I-ANP binding. The competitive binding assay with des[Gln18,Ser19,Gly20,Leu21, Gly22]ANP-(4-23)-NH2 (C-ANF-4-23), a specific ligand for the C receptor, revealed that the decrease in the 125I-ANP binding by norepinephrine was caused by the down-regulation of the C receptor. Isoproterenol also down-regulated the C receptor in a time- and dose-dependent manner. The catecholamine-induced down-regulation of the C receptor was antagonized by a beta 2-selective adrenergic antagonist, ICI 118,551 but not by an alpha 1-, alpha 2-, or beta 1-adrenergic antagonist. Forskolin, NaF and, 8-bromo-cyclic AMP also decreased the C receptor density. The isoproterenol-induced decrease in the C receptor level was further confirmed by affinity cross-linking and Western blot analysis. Northern blot analysis revealed that isoproterenol and 8-bromo-cyclic AMP decreased the steady-state level of C receptor mRNA. By contrast, neither the ANP-A receptor nor the ANP-B receptor mRNA level was affected by 8-bromo-cyclic AMP. The nuclear run-on assay showed that the transcriptional rate of the C receptor gene was decreased by isoproterenol, whereas those of the ANP-A and ANP-B receptor genes were unchanged. Isoproterenol attenuated the clearance of exogenously added ANP and augmented the ANP-stimulated intracellular cyclic GMP production to the same extent as the selective occupancy of the C receptor with C-ANF-(4-23), suggesting that the isoproterenol-induced enhancement of responsiveness to ANP could result not from the sensitization of the ANP-A or ANP-B receptor but from the down-regulation of the C receptor, which leads to the attenuated clearance of ANP. These findings suggest that the beta 2-adrenergic receptor stimulation down-regulates the C receptor through the decrease in the transcriptional rate of the C receptor gene and that the activation of the sympathetic nervous system augments the biological responsiveness to natriuretic peptides by attenuating their metabolic clearance in vascular walls.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1994

Functional anatomy of taste perception in the human brain studied with positron emission tomography.

Regional cerebral blood flow (rCBF) was measured with positron emission tomography (PET) in 10 normal volunteers with the purpose of measuring rCBF changes related to taste physiology. Discrimination of 0.18% saline from pure water was associated with significantly increased rCBF values in the thalamus, the insular cortex, the anterior cingulate gyrus, the parahippocampal gyrus, the lingual gyrus, the caudate nucleus, and the temporal gyri. The results indicate that rCBF changes in these structures may reflect oral exposure to salt.

Adolescent↗
PubMed1994

Expression of biologically active receptors for natriuretic peptides in the human uterus during pregnancy.

Human amnion cells secrete a large amount of brain natriuretic peptide (BNP). In the present study, to elucidate the possible roles of amniotic BNP during the course of human pregnancy, the tissue distributions of biologically active receptors of natriuretic peptides, atrial natriuretic peptide (ANP)-A receptor and ANP-B receptor in the human uterus during pregnancy were investigated by Northern blot analysis and an in vitro guanosine 3',5'-cyclic phosphate (cGMP) generation assay, the second messenger of natriuretic peptides, using crude membrane preparations. Both ANP-A and ANP-B receptor mRNAs were detected in the tissues of decidua vera, chorion laeve, myometrium and placenta. The in vitro cGMP generation assay revealed that the expression of ANP-A receptor was more prominent than that of ANP-B receptor in these tissues. On the other hand, in amniotic tissue only ANP-B receptor mRNA was weakly expressed but ANP-A receptor mRNA was not detected.

Atrial Natriuretic Factor↗
PubMed1994

Functional evidence for an apical ANP receptor in LLC-PK1 kidney epithelial cells.

The localization of natriuretic peptide receptors was studied in LLC-PK1 cell monolayers grown on a micro-porous membrane filter. The addition of alpha-human atrial natriuretic peptide (alpha-hANP) to the apical side of the cells produced a concentration-dependent increase in cyclic GMP (cGMP) formation, the extent of which was similar to that produced by the addition to the basolateral side. More cGMP was formed with alpha-hANP (1 and 100 nM) than with the C-type natriuretic peptide (100 nM). These findings indicate that the biologically active receptors with high efficacy for alpha-hANP are expressed in both the apical and basolateral membranes in LLC-PK1 cells.

Animals↗
PubMed1994

Iron ion induces mitochondrial DNA damage in HTC rat hepatoma cell culture--role of antioxidants in mitochondrial DNA protection from oxidative stresses.

The mitochondrial DNA (mtDNA) is exposed to the reactive oxygen species generated in the mitochondrial electron transfer system. While mitochondrial superoxide dismutase (Mn-SOD) scavenges superoxide anions to prevent damage of mtDNA, excess amount of reactive oxygen generated by quinone compounds impairs the mtDNA, in which involvement of iron ion-catalyzed reactions is suggested. In this communication, we report that the mtDNA in HTC rat hepatoma cells was markedly damaged in the presence of either ferrous (Fe2+) or ferric (Fe3+) iron in the culture medium. The mtDNA of HTC cells was damaged in the presence of 100 microM of iron ions in the culture medium within 3 h. There was no significant difference in the potency of Fe2+ and Fe3+. Deferoxamine, a Fe(3+)-specific chelating reagent, blocked the iron ion-induced mtDNA damage completely. The mtDNA in rat hepatocyte primary culture was, on the other hand, not damaged by either Fe2+ or Fe3+. To understand the difference between iron ion-induced damage of mtDNA in HTC cells and in the primary hepatocytes, the Mn-SOD activity and lipid-soluble antioxidant contents were compared. The Mn-SOD activity in HTC cells was markedly lower (< 0.02 U/mg cell protein) than that in rat hepatocyte primary cell cultures (1.5 U/mg cell protein). Immunoreactive Mn-SOD content in HTC cells was also lower (21 ng/mg cell protein) than in the primary cultures (99 ng/mg cell protein). HTC cells contain much smaller amounts (3-11% of that of normal rat hepatocytes) of alpha-tocopherol and coenzyme Q homologs (CoQn). These results suggest that reactive oxygen species produced by iron ion impaired mtDNA of HTC cells, in which antioxidant activity was markedly decreased.

Animals↗
PubMed1994

Preferential alternative splicing in cancer generates a K-sam messenger RNA with higher transforming activity.

K-sam, also designated fibroblast growth factor receptor 2/BEK, was originally cloned from a stomach cancer cell line KATO-III. The gene is amplified and overexpressed preferentially in poorly differentiated types of stomach cancers. The major K-sam transcript in KATO-III cells encodes a receptor protein with a truncated carboxyl terminus and with a high-affinity binding site for keratinocyte growth factor. This truncated type is produced by an alternative splicing mechanism, and in normal tissues, the truncated type is far less prevalent than the untruncated form. The variant K-sam complementary DNA lacks tyrosine 769, which is a putative phospholipase C gamma 1 association site, and showed a higher transforming activity to NIH3T3 cells than the untruncated form, which is identical with the keratinocyte growth factor receptor.

3T3 Cells↗
PubMed1994

Experimental carcinogenesis in the rat intestine induced by two different carcinogens--evaluation of carcinogenic action and its effect on ornithine decarboxylase activity.

Carcinogenesis in the rat intestine induced with 1,2-dimethylhydrazine (DMH), N-methyl-N-nitrosourea (MNU), and their combinatorial use was studied. Intestinal tumors, including both adenoma and adenocarcinoma, were induced in all the rats given the carcinogens. The tumor frequently occurred in the intestinal tract extending from the duodenum to the colon in the DMH treated group. In the MNU treated group, the tumor occurred in the colon, especially on the distal side. Distribution of tumors in the group treated with both carcinogens was similar to that seen in the MNU-treated group. Neither obvious macroscopic nor histological differences were observed between groups treated with these carcinogens. In addition, we investigated the effect of carcinogens on ornithine decarboxylase (ODC) activity in rat colon. Tumor tissues showed a remarkably high level of enzyme activity compared with the normal-appearing mucosa, and there was a correlation between the level of the ODC activity and the histological grade of malignancy. ODC activity in the normal-appearing mucosa of the carcinogens-treated rats was significantly higher than that of control rats, and the number of tumors per rat was correlated with the level of ODC activity. These results indicate that mucosal ODC may be a pertinent biological marker for local carcinogenic activity.

1,2-Dimethylhydrazine↗
PubMed1994

Detection of C-type natriuretic peptide in human circulation and marked increase of plasma CNP level in septic shock patients.

We have previously reported that C-type natriuretic peptide (CNP), the third member of natriuretic family, was produced in vascular endothelial cells and hypothesized that CNP might be a local regulator of vascular tone and/or growth from endothelial cells. In order to clarify the pathophysiological significance of CNP in humans, we examined the presence of CNP in human circulation and determined plasma levels of CNP in patients with various cardiovascular disorders. The plasma level of CNP in healthy persons was 1.4 +/- 0.6 fmol/ml (n = 13). The plasma level of CNP was markedly increased in patients with septic shock (13.2 +/- 10.1 fmol/ml, n = 11), while there was no alteration in patients with congestive heart failure or hypertension. There was two-fold increase of the plasma CNP level in patients with chronic renal failure. These results indicate that CNP, which can be considered as an endothelium-derived relaxing peptide, is detectable in human circulation and suggest the pathophysiological significance of endothelial CNP in humans.

Aged↗
PubMed1994

Mast cell protease inhibitor, trypstatin, is a fragment of inter-alpha-trypsin inhibitor light chain.

The mast cell protease inhibitor trypstatin was purified from rat peritoneal mast cells (Kido, H., Yokogoshi, Y., and Katunuma, N. (1988) J. Biol. Chem. 263, 18104-18107). We noticed that trypstatin could possibly be identical with the second half of inter-alpha-trypsin inhibitor light chain (ITI-LC), because only 5 amino acid residues of trypstatin are different from the sequence deduced from the recently reported rat ITI-LC mRNA. Southern blot analysis revealed that a 170-base pair probe corresponding to the second half of rat ITI-LC hybridized to the digested rat genomic DNAs only at single bands even in low stringency conditions. Similarly, a 170-base pair probe corresponding to the human counterpart, which differs by 10 deduced amino acids from the rat probe, also hybridized to the digested rat genomic DNAs only at single bands at the same positions and same conditions. These results suggest that rat trypstatin is genetically identical with rat ITI-LC. ITI-LC/trypstatin mRNA was not detected in rat peritoneal mast cells by RNA blot nor by reverse transcription-polymerase chain reaction analysis. Since trypstatin was purified from rat peritoneal mast cells and the cells were immunohistochemically positive with anti ITI-LC antibody, ITI-LC/trypstatin may be taken up into mast cell granules from the serum but may not be generated by mast cells themselves.

Alpha-Globulins↗
PubMed1994

Contractile actions of endothelins in rat gastric body: evidence for receptor subtypes and involvement of prostaglandin E2.

Endothelin-1 produced a phasic contraction in the longitudinal muscle preparation isolated from the rat gastric body, but produced a sustained contraction in the circular muscle preparation. Indomethacin, a cyclo-oxygenase inhibitor, decreased the endothelin-1-induced contraction of the longitudinal preparation, but did not affect the endothelin-1-induced contractions of the circular muscle. In the absence of indomethacin, the maximal contractile tension (Emax) and the concentration producing a half-maximal contraction (EC50) induced by endothelin-3 in the longitudinal muscle preparations were smaller than those for endothelin-1, whereas in the circular muscle preparations there were no significant differences between the values (EC50, Emax) for endothelin-1 and endothelin-3. In the presence of indomethacin, endothelin-3-induced contraction of the longitudinal muscle preparation is more potent than that of endothelin-1. SC-19220, a prostaglandin E2 receptor antagonist, significantly decreased endothelin-1-induced contraction of the longitudinal preparation, prostaglandin E2 produced a concentration-dependent contraction in the longitudinal preparation, but had no effects in the circular muscle preparation. Endothelin-1 (10(-8) M) significantly increased the release of immunoassayable prostaglandin E2 from rat gastric smooth muscle. These results point to the existence of distinct endothelin receptor subtypes in the smooth muscle of rat gastric body, and a potential role of endothelin-1 in regulating gastric motility. Moreover, one of the endothelin receptor subtypes is related to the production of prostaglandin E2.

Animals↗
PubMed1994

A high-resolution cytogenetic map of human chromosome 9: localization of 203 new cosmid markers by direct R-banding fluorescence in situ hybridization.

A high-resolution cytogenetic map of human chromosome 9 was constructed with 203 newly isolated cosmid markers by direct R-banding fluorescence in situ hybridization. The clones were localized preferentially to R-positive bands throughout chromosome 9. Although the number of clones was roughly proportional to the R-band size, many more clones (ca. 80) were mapped at the q34 region compared to its physical size. Based on these cytogenetic mapping data, one can establish physical contig maps with cosmids and yeast artificial chromosomes and a genetic linkage map essential for positional cloning of responsible genes.

Animals↗
PubMed1994

Preferential expression of the third immunoglobulin-like domain of K-sam product provides keratinocyte growth factor-dependent growth in carcinoma cell lines.

Previously, we identified an amplified gene in a stomach cancer cell line, KATO-III, and designated it K-sam. This gene was later found to be identical with a gene for a receptor tyrosine kinase, bek/FGFR2. One of the characteristics of the K-sam gene is structural diversity of its transcripts; K-sam complementary DNA (cDNA) cloned from human brain (K-sam-I) has a completely different sequence at the third extracellular immunoglobulin-like domain as compared to that of the K-sam cDNA derived from KATO-III cells (K-sam-II). Recent study has revealed that this difference signifies a differential ligand affinity; the receptor encoded by the K-sam-I cDNA has a high affinity for basic fibroblast growth factor (bFGF), while the K-sam-II cDNA corresponds to a receptor with the high affinity for keratinocyte growth factor (KGF). Reverse transcription-polymerase chain reaction and RNA blot analysis showed that the K-sam-II-type transcript was present in carcinoma cell lines but not in any of the sarcoma cell lines examined. The K-sam-I-type transcript was expressed in both carcinoma and sarcoma cell lines. Furthermore, KGF enhanced the DNA synthesis of the esophageal cancer cells, TE-1, in a dose-dependent manner, while the effect of bFGF was not substantial. In contrast, the glioblastoma cell line, A-172, that expressed the bFGF receptor showed a mitogenic response to bFGF but not to KGF. These data suggest that KGF is a growth factor used preferentially in cancer cells, and this preference is based on the presence of the K-sam-II-type receptor in carcinoma cells but not in sarcoma cells due to alternative splicing.

Base Sequence↗
PubMed1994

Calcium phosphate precipitation on the surface of HA-G-Ti composite under physiologic conditions.

Hydroxyapatite-glass-titanium (HA-G-Ti) functionally gradient composite plates bound face-to-face by nylon wire were soaked in a simulated body fluid. The gap between the plates was filled with the precipitates after soaking for 6 months, and a tight chemical bond was formed between them. Field emission-type (FE) scanning electron microscopy (SEM) and transmission electron microscopy observations revealed that the growth rate and morphology of the precipitates differed widely from the outside portion to the inside one on the surface region of the composite plates. In the portion relatively near the outside, the mutually bonded portion, needle-like precipitates with preferred orientation to the c-axis were markedly observed. From the results of Fourier transform infrared spectroscopy and energy dispersive x-ray microanalysis, it was found that the precipitates were Ca-deficient carbonate apatite with low crystallinity. On the other hand, HA-G-Ti composite rods were implanted in the femur of beagle dogs for 3 months. FE-SEM observations demonstrated that needle-like precipitates were deposited on both the surfaces of the composite and bone at the portion having a narrow gap, about 0.1-0.2 mm between them prepared deliberately before implantation. It was found that both the morphologies and the composition of the precipitates in vivo were similar to those in vitro. It is concluded that the HA particles on the surface of the composite act as nucleation sites for precipitation in physiologic environments, whereas the glass matrix is independent to it.

Animals↗