Biomedical subjects

M Satoh

Publications and source records attributed to M Satoh.

At least 325 records · Page 18Linked to original sources

PubMed1997

Abnormal telomere dynamics of B-lymphoblastoid cell strains from Werner's syndrome patients transformed by Epstein-Barr virus.

The characteristics of B-lymphoblastoid cell strains transformed by Epstein-Barr virus (EBV) from normal individuals and Werner's syndrome (WRN) patients were compared. We continuously passaged cell strains from 28 WRN patients and 20 normal individuals for about 2 years corresponding to over 160 population doubling levels (PDLs). First, the WRN mutation significantly suppressed the immortalization: all the 28 cell strains from WRN patients, as well as 15 out of 20 cell strains from normal individuals, died out before 160 PDLs mostly without developing a significant telomerase activity. The remaining five cell strains from normal individuals became moderately/strongly telomerase-positive and, three of them were apparently immortalized with an infinitively proliferating activity. Second, the monitoring of the telomere length of both normal and WRN cell strains during the culture period suggests that the WRN gene mutation causes abnormal dynamics of the telomere: (1) a significant proportion of WRN cell strains showed drastic shortening or lengthening of telomere lengths during cell passages compared with normal cell strains, and (2) WRN cell strains terminated their life-span at a wide range of telomere length (between 3.5 and 18.5 Kbp), whereas normal cell strains terminated within a narrow telomere length range (between 5.5 and 9 Kbp). The chromosomal aberration characteristic of WRN cells, including translocation was confirmed in our experiment. We discussed the correlation between the chromosomal instability, abnormal telomere dynamics and inability of immortalization of the WRN B-lymphobloastoid cell strains.

B-Lymphocytes↗

PubMed1997

Type 2 interleukin-1 receptor mRNA is induced by kainic acid in the rat brain.

The in situ hybridization technique was used to examine the expression of type 2 interleukin-1 receptor (IL-1R2) mRNA in the rat brain following the systemic injection of kainic acid at a convulsive dose. The expression of IL-1R2 mRNA was not detected in any brain regions of the saline-injected control rats. 8 h after the systemic injection of kainic acid, weak expression of IL-1R2 mRNA was observed in the dentate gyrus and basolateral amygdaloid nucleus. At 12 and 24 h after the injection of kainic acid, IL-1R2 mRNA was markedly induced in various brain regions including the CA1 and CA3 fields of the hippocampus, dentate gyrus, basolateral amygdaloid nucleus, piniform cortex, claustrum, tenia tecta, arcuate hypothalamic nucleus, dorsomedial hypothalamic nucleus, suprachiasmatic nucleus, tuberal magnocellular nucleus and supramammillary nucleus. In these regions, the signals of IL-1R2 mRNA were observed on likely neuronal cells. Around the mediodorsal thalamic nucleus and the paraventricular thalamic nucleus, dispersed intense signals were observed on the non-neuronal cells. In addition, the expression of the mRNA on the venules was observed at 12 h. The strength of signals significantly decreased by 48 h after the injection. These findings revealed the spatiotemporal induction of IL-1R2 mRNA in the rat brain following the systemic administration of kainic acid, which has shown to cause neuronal degeneration, suggesting the pathological roles of IL-1R2 in the brain.

Animals↗

PubMed1997

L-DOPA neurotoxicity is mediated by glutamate release in cultured rat striatal neurons.

The exposure of cultured rat striatal neurons to L-DOPA caused marked cell death. The L-DOPA cytotoxicity was inhibited by the addition of Mg2+ to and by the removal of Ca2+ from the culture medium, and also by the application of tetrodotoxin. Moreover, prolonged application of L-DOPA increased the glutamate content in the culture medium. These results indicate that L-DOPA produces neurotoxicity by facilitating glutamate release.

Animals↗

PubMed1997

Beta2-adrenoceptors on the glial cells mediate the induction of interleukin-1beta mRNA in the rat brain.

Interleukin-1beta mRNA was induced by i.c.v. injection of the beta-adrenoceptor agonist isoproterenol. Lower doses of procaterol, a beta2-adrenoceptor agonist showed stronger induction of the mRNA than isoproterenol. These inductions were primarily observed in the glial cells. On the other hand, the beta1-adrenoceptor agonist dobutamine induced expression of this mRNA only in the meninges. These results suggest the existence of a system for regulation of interleukin-1beta gene expression via beta2-adrenoceptors in the brain parenchyma.

Adrenergic beta-Agonists↗

PubMed1997

Intracerebroventricular injection of isoproterenol produces its analgesic effect through interleukin-1beta production.

The effects of isoproterenol, a beta-adrenoceptor agonist, on the production of interleukin-1beta in the brain and on mechanical nociception were examined in rats. Intracerebroventricular (i.c.v.) injection of isoproterenol at the dose of 3 microg/rat markedly induced interleukin-1beta mRNA in the molecular layer of the hippocampus, medial preoptic area, paraventricular thalamic nucleus, paraventricular hypothalamic nucleus, ventromedial hypothalamic nucleus, dorsomedial hypothalamic nucleus and central gray 1 h after injection. In these regions, interleukin-1beta mRNA was expressed mainly in the glial cells. The thresholds to the mechanical stimulation to the hind paw were elevated by i.c.v. administration of isoproterenol (1 to 10 microg/rat). When isoproterenol was given at the dose of 3 microg/rat, the analgesic effect showed two peaks. The first peak was observed at 60 min after injection and the second was observed at 180 min. The second phase of analgesia was antagonized by coadministration of interleukin-1 receptor antagonist. These results suggest that isoproterenol produces an analgesic effect, at least in part, through the induction of interleukin-1beta expression in the brain.

Analgesics↗

PubMed1997

Characterization of human endothelin B receptor and mutant receptors expressed in insect cells.

Endothelin type-B receptor (ET(B)R) forms a stable complex with its ligand, endothelin-1. To facilitate biochemical and biophysical studies of human ET(B)R, several ET(B)R mutants carrying a hexahistidine tag sequence at the N or C terminus were expressed in Sf9 cells and were purified by a combination of biotinylated endothelin-1-ligand-affinity and nickel-affinity chromatographies. The ligand-free receptor was purified by dissociating the ligand x receptor complex with 2 M NaSCN, whereas the ligand-bound ET(B)R was purified by the use of thiol-sensitive biotinylated endothelin-1. While the wild-type ET(B)R was expressed at about 100 pmol 125I-endothelin-1-binding activity/mg membrane protein, the deletion of 36 residues from the N-terminus reduced the expressed activity to about 30%. On the other hand, the lack of glycosylation and the replacement of 2-9 residues in the N-terminal tail resulted in a 20-40% reduction in the expressed activity. Among the mutant proteins, [H57-H62, G63-G65]ET(B)R, carrying six His residues in the N-terminal tail, was studied extensively because it was purified most effectively. Ligand-free [H57-H62, G63-G65]ET(B)R, purified in digitonin, retained full ligand-binding activity, while other detergents led to partial denaturation of the receptor after solubilization or after elution with NaSCN. On the other hand, ligand-bound [H57-H62, G63-G65]ET(B)R could be purified in various detergents, such as n-octyl-beta-D-glucopyranoside or n-decyl-beta-D-maltopyranoside. Ligand-free [H57-H62, G63-G65]ET(B)R reconstituted in phospholipid vesicles stimulated the binding of guanosine 5'-3-O-(thio)triphosphate by Gq in the presence of endothelin-1. Ligand-bound [H57-H62, G63-G65]ET(B)R showed similar catalytic activity in nucleotide exchange by Gq. These results indicate that the ligand x receptor complex in a detergent-micellar solution retained the biologically active structure, and that the presence of ligand, endothelin-1, in the receptor molecule reinforces the stable assembly of a helical bundle and therefore the active structure.

Amino Acid Sequence↗

PubMed1997

Down-regulation of the defective transcripts of the Werner's syndrome gene in the cells of patients.

Werner's syndrome (WS), an adult progeria, is a recessive genetic disorder caused by the mutations in the DNA helicase gene (WRN). In this study, a comparative northern blot analysis was made for poly(A)+ RNAs extracted from fibroblasts and B-lymphoblastoid cells of WS patients, relatives of patients, and normal individuals. The levels of mutant WRN mRNA from patient cells were significantly lower than those of intact mRNA from the cells of normal individuals by an average of 70%. Furthermore, an extremely low level of WRN mRNA(s), presumably a mixture of mutant and intact mRNAs, was observed for the patient's family members who carry one mutated allele. These results strongly suggest that a relatively low level of helicase mRNA is sufficient to prevent the onset of Werner's syndrome.

Adult↗

PubMed1997

Inhibitory effects of a fullerene derivative, dimalonic acid C60, on nitric oxide-induced relaxation of rabbit aorta.

Dimalonic acid C60 (10(-5) M), a new fullerene derivative, produced an augmentation of phenylephrine-induced tone and reduced both the acetylcholine-induced maximum relaxation and the amplitude of substance P (10(-8) M)-induced relaxation in endothelium-containing thoracic aorta of rabbit; the acetylcholine- and substance P-induced relaxation was restored in the presence of superoxide dismutase (250 U/ml). Dimalonic acid C60 (10(-5) M) did not influence the phenylephrine-induced contractile response in the absence of endothelium, but the acetylcholine-induced relaxation was eliminated by removal of the endothelium. Superoxide anion generation, using hypoxanthine (1 mM)/xanthine oxidase (16 mU/ml), reduced the acetylcholine-induced relaxation and produced an augmentation of phenylephrine-induced tone in endothelium-containing strips; these effects were negated by the addition of superoxide dismutase (250 U/ml). A nitric oxide-generating agent, S-nitroso-N-acetylpenicillamine, caused relaxation of aorta without endothelium in a concentration-dependent manner, and the concentration-response curve was shifted to the right in the presence of dimalonic acid C60. This inhibitory effect of dimalonic acid C60 was also masked in the presence of superoxide dismutase. Sodium nitroprusside-induced relaxation was not affected by either dimalonic acid C60 or superoxide dismutase. These observations suggest that dimalonic acid C60 inhibits endothelium (nitric oxide)-dependent agonist-induced relaxation through the production of superoxide.

Acetylcholine↗

PubMed1997

Induction of macrophage inflammatory protein MIP-1alpha mRNA on glial cells after focal cerebral ischemia in the rat.

The distribution and cell source of macrophage inflammatory protein-1alpha (MIP-1alpha) mRNA induced by transient and permanent middle cerebral artery occlusion (MCAO) were investigated by a double in situ hybridization technique. The distribution and time course of the induction of MIP-1alpha mRNA were similar in the two MCAO models. MIP-1alpha mRNA was not detected in the sham-operated rat brain. MIP-1alpha mRNA was induced by MCAO with the peak of expression at 4-6 h after the onset of occlusion, and the signals of MIP-1alpha mRNA were observed in the ischemic core region at an earlier time point, and thereafter intensely in the penumbra of the ischemic area. The signals of MIP-1alpha mRNA were evident on Mac-1alpha mRNA-positive cells, but not on glial fibrillary acidic protein (GFAP) mRNA-positive cells, indicating that MIP-1alpha mRNA was induced in microglia/macrophages of the rat brain after focal cerebral ischemia.

Animals↗

PubMed1997

Human anti-nuclear ribonucleoprotein antigen autoimmune sera contain a novel subset of autoantibodies that stabilizes the molecular interaction of U1RNP-C protein with the Sm core proteins.

Anti-Sm Abs recognize Sm core proteins B'/B, D, E, F, and G, shared by U1, U2, U4-6, and U5 small nuclear ribonucleoproteins (snRNPs), while anti-nuclear ribonucleoprotein Ag (nRNP) Abs recognize the U1 RNP-specific 70K, A, and C proteins. However, although the autoimmune response to U1 snRNPs involves all components of the particle, not all are recognized equally. For example, all human anti-nRNP sera contain Abs against native U1-C, in contrast to their absence in MRL/lpr mice. In this study, autoantibody recognition of native U1 snRNPs was investigated by dissociating the particle into four components (U1-70K, U1-A, U1-C, and the Sm core particle) using 1 M MgCl2 or ribonuclease treatment. As expected, human anti-Sm and MRL/lpr sera immunoprecipitated only the Sm core proteins, and human anti-nRNP/Sm sera immunoprecipitated the Sm core proteins plus U1-C under both conditions. However, although human anti-nRNP sera immunoprecipitated U1-C when U1 snRNPs were dissociated before Ab binding, they unexpectedly immunoprecipitated the Sm core proteins when Abs were bound before dissociation. This apparent paradox was explained by the stabilizing effects of anti-nRNP sera on interactions of U1-C with the Sm core particle. All human anti-nRNP sera contained high levels of autoantibodies that prevent dissociation of U1-C from the U1 snRNP. These Abs were absent in MRL/lpr mice. Human autoimmune sera may prevent dissociation by recognizing the quaternary structure of the U1-C-Sm core protein complex or by altering its conformation. Stabilization of U1 snRNPs by autoantibodies could influence Ag processing and presentation, possibly with important effects on the development of autoimmunity to U1 snRNPs.

Animals↗

PubMed1997

Antagonist activity of [Thr18,gamma-methylleucine19]endothelin-1 in human endothelin receptors.

Receptor binding and antagonist properties of endothelin-1 analogues, [Thr18,gamma-methylleucine19]endothelin-1, [Thr18,Leu19]endothelin-1 and [Thr18,cyclohexylalanine19]endothelin-1, were investigated using cloned human endothelin ET(A) and ET(B) receptors expressed in Chinese hamster ovary cells. Among them, [Thr18,gamma-methylleucine19]endothelin-1 had a high affinity for endothelin ET(A) and ET(B) receptors with respective Kd values of 300 and 110 pM and had no agonist activity on the stimulation of arachidonic acid release in endothelin ET(A) and ET(B) receptor-expressing cells. [Thr18,gamma-methylleucine19]Endothelin-1 had potent antagonist activity in endothelin-1-induced arachidonic acid release in endothelin ET(A) and ET(B) receptor-expressing cells with respective pA2 values of 8.2 and 8.5. In an inositol phosphates accumulation assay, [Thr18,gamma-methylleucine19]endothelin-1 also exhibited potent antagonist activity for endothelin ET(A) and ET(B) receptors with respective pA2 values of 8.0 and 8.4. In conclusion, [Thr18,gamma-methylleucine19]endothelin-1 acts as a potent and nonselective antagonist with no agonist activity for cloned human endothelin ET(A) and ET(B) receptors.

Animals↗

PubMed1997

Cloning and characterization of a novel gene, WS-3, in human chromosome 8p11-p12.

A novel human gene referred to as the WS-3 gene, in the short arm of human chromosome 8, was cloned by a combination of exon trapping, thermal asymmetric interlaced-PCR (TAIL-PCR) and the Marathon-Ready cDNA amplification method. The gene consists of 7 exons separated by 6 introns, and is at the telomere side of the STS marker, D8S1055. The full-length WS-3 gene contains 1052 nucleotides and codes for a protein of 190 amino acids with a calculated mol. wt. of 20,747. Southern blot experiments showed that the WS-3 gene exists as a single copy in the human genome. A protein encoded by the WS-3 gene has an R-G-D (Arg-Gly-Asp) motif in the N-terminal region, which seems to confer adhesive properties to macromolecular proteins like fibronectin. Although WS-3 is a small gene with unknown biological function, its ubiquitous expression in various tissues and organs suggests that the encoded protein is one of the essential components of all organs and tissues.

Amino Acid Sequence↗

PubMed1997

Promotion of neurogenesis in mouse olfactory neuronal progenitor cells by leukemia inhibitory factor in vitro.

Olfactory neuronal progenitor cells were partially purified from the olfactory epithelia of 14.5-day-old mouse embryos by an immuno-killing method with an antibody against neural adhesion molecule (N-CAM). Immunostaining study showed that about 60% of the population after immunokilling, was class-III beta-tubulin-/keratin-neuronal progenitor cells and that they differentiated into N-CAM+/class-III beta-tubulin+ neurons in a chemically-defined medium within 1 day in culture. A part of them proliferated prior to their neuronal differentiation as determined by the incorporation of bromodeoxyuridine (BrdU) into neuronal nuclei. Leukemia inhibitory factor (LIF), but not ciliary neurotrophic factor or interleukin-6, increased the proportion of the BrdU-labeled neurons in vitro. These results suggest LIF promotes the neurogenesis in the olfactory neuronal progenitor cells.

Animals↗

PubMed1997

Inducible nitric oxide synthase and tumor necrosis factor-alpha in myocardium in human dilated cardiomyopathy.

OBJECTIVES: We examined the mRNA expression and protein localization of inducible nitric oxide synthase (iNOS) and tumor necrosis factor-alpha (TNF-alpha) in myocardial tissue obtained from patients with dilated cardiomyopathy (DCM). BACKGROUND: The etiology of DCM is unknown, but viral infection or autoimmune abnormalities that induce cytokine expression have been proposed as pathogenetic factors. Nitric oxide (NO), synthesized by nitric oxide synthase (NOS), has negative inotropic and cytotoxic effects on cardiomyocytes. Cytokines such as TNF-alpha are potent stimulators of iNOS expression. Expression of iNOS leads to excessive production of NO in the myocardium and may modulate cardiac contractility and ventricular morphology. METHODS: We examined the mRNA expression and protein localization of iNOS and TNF-alpha in myocardial tissue obtained from 24 patients with DCM, 20 patients with hypertrophic cardiomyopathy (HCM) and 15 control subjects, using the reverse transcriptase-polymerase chain reaction method and immunohistochemical studies. We then compared the differences in clinical characteristics between DCM patient subgroups with and without myocardial iNOS expression. RESULTS: Messenger RNA expression of iNOS and TNF-alpha was observed, respectively, in 13 (54%) and 18 (75%) patients with DCM. Gene expression of TNF-alpha was consistently detected in endomyocardial tissue from patients with DCM and INOS expression. Inducible NOS protein was evident only in cardiomyocytes, whereas TNF-alpha was apparent in both cardiomyocytes and endomyocardial endothelium. Neither mRNA expression nor protein localization of iNOS or TNF-alpha was observed in cardiac tissue obtained from patients with HCM or control subjects. Patients with DCM and iNOS mRNA showed a lower left ventricular ejection fraction (p < 0.01) and a higher left ventricular volume (p < 0.05) than the negative DCM group. CONCLUSIONS: Inducible NOS was consistently coexpressed with TNF-alpha in myocardial tissue obtained from a subgroup of patients with DCM and advanced left ventricular dysfunction.

Adult↗

PubMed1997

Direct evidence for increase in excitatory amino acids release during mossy fiber LTP in rat hippocampal slices as revealed by the patch sensor methods.

We had previously established a patch sensor system for detecting overflow of excitatory amino acids (EAA) from hippocampal slices induced by a single electric stimulus. We performed simultaneous recordings of patch sensor current and whole-cell current in rat hippocampal slices. Tetanus of mossy fibers produced long-term potentiation (LTP) of excitatory postsynaptic current (EPSC) recorded from a CA3 pyramidal cell with an increase in single electric stimulus-evoked patch current amplitude recorded with a patch sensor positioned in the stratum lucidum. In Schaffer collateral-CA1 synapses, however, LTP of EPSC was accompanied by an increase in AMPA-evoked whole-cell current, but not with change in patch current in the stratum radiatum. These results indicate that EAA release is increased during mossy fiber LTP but not CA1 LTP.

Animals↗

PubMed1997

(3R)-N-(1-(tert-butylcarbonylmethyl)-2,3-dihydro-2-oxo-5-(2-pyridyl)-1H-1,4-benzodiazepin-3-yl)-N'-(3-(methylamino)phenyl)urea (YF476): a potent and orally active gastrin/CCK-B antagonist.

A number of new 1,4-benzodiazepin-2-one-based gastrin/CCK-B receptor antagonists related to the archetypal analogue L-365,260, and more closely to the recently reported compound YM022, have been synthesized and evaluated for biological activity. The compounds were screened for their ability to inhibit the binding of [125I]CCK-8 to gastrin/CCK-B receptors prepared from rat brains and that of [3H]L-364,718 to CCK-A receptors from rat pancreas, and were shown to be potent and selective ligands for the gastrin/CCK-B receptor. Functional studies in vivo demonstrated the compounds to be antagonists of the receptor as evidenced by their ability to inhibit pentagastrin-induced gastric acid secretion in anesthetized rats. More extensive evaluation in vivo included determination of ED50 values in the rat acid secretion model for selected compounds and an examination of the effect of these compounds on pentagastrin-induced gastric acid secretion in Heidenhain pouch dogs following oral and intravenous administration. Two compounds, i.e. (3R)-N-[1-[(tert-butylcarbonyl)methyl]-2,3-dihydro-2-oxo-5-(2-pyri dyl) -1H-1,4-benzodiazepin-3-yl]-N'-[3-(methylamino)phenyl]urea, 15c (YF476), and (3R)-N-[1-[(tert-Butylcarbonyl)methyl]-2,3-dihydro-2-oxo-5- (2-pyridyl)-1H-1,4-benzodiazepin-3-yl]-N'-[3-(dimethylamino)phenyl ]urea hydrochloride, 15d, showed potent dose-dependent effects in both models with the former showing excellent oral bioavailability and an ED50 of 21nmol/kg po in dogs. 15c is currently under clinical investigation for the treatment of gastro-oesophagal reflux disease (GORD).

Administration, Oral↗

PubMed1997

Human autoantibodies stabilize the quaternary structure of Ku antigen.

OBJECTIVE: To examine humoral immune responses to the native Ku antigen and to evaluate the role of autoantibodies in stabilizing intermolecular contacts between the p70 and p80 Ku subunits. METHODS: Recombinant free human p70 and p80 Ku subunits and p70/p80 heterodimers were expressed in Sf9 (insect) cells using baculovirus vectors. Affinity-purified recombinant human p70, p80, and p70/p80 dimer were studied by enzyme-linked immunosorbent assay (ELISA) and immunoprecipitation to evaluate autoantibody specificities in sera from 58 patients with systemic autoimmune disease. RESULTS: Anti-Ku antibodies were detected by ELISA or immunoprecipitation using K562 cell Ku antigen. All of the sera were reactive with the native recombinant p70, p80, or p70/p80 antigens: 47% were anti-p70+,anti-p80+ and 32% were anti-p70-,anti-p80+, but only 3% were anti-p70+,anti-p80-. Unexpectedly, 18% of the sera recognized the p70/p80 dimer but did not recognize native p70 or p80 alone. A subset of sera containing autoantibodies that prevent the dissociation of p70 from p80 by high salt and detergent treatment was identified; monoclonal antibody (MAb) 162, a murine anti-Ku MAb, displays the same property. Autoantibodies that stabilize the p70-p80 interaction were found most frequently in sera containing both anti-p70 and anti-p80 antibodies. CONCLUSION: Autoantibodies to the native p80 subunit of Ku are more common than are anti-p70 antibodies. When anti-p70 antibodies were detected, they generally were found together with anti-p80. A novel type of autoantibody capable of stabilizing the p70/p80 heterodimer was identified in human sera for the first time. These "stabilizing" autoantibodies are found in sera containing both anti-p70 and anti-p80 antibodies, and also are produced by mice immunized with human Ku antigen. Autoimmunity to Ku may be initiated with an immune response to p80, followed by spreading to p70. We hypothesize that stabilizing antibodies could facilitate the spreading of autoimmunity from one subunit of Ku to another by altering the processing of p70 or p80 by antigen-presenting cells.

Animals↗

PubMed1997

Natural history of a spontaneous dissecting aneurysm of the proximal superior mesenteric artery: report of a case.

We report herein the case of a 44-year-old man in whom an asymptomatic dissecting aneurysm was found in the proximal part of the superior mesenteric artery (SMA) during a preoperative evaluation for colon cancer. The patient was managed conservatively with blood pressure control during the perioperative period of the colon resection as the false lumen of the dissecting aneurysm was revealed to be completely occluded by thrombus. The thrombus in the false lumen continued to be absorbed until 1 month after surgery. The patient is currently well 4 years after his operation without any evidence of recurrence of the aneurysm.

Adenocarcinoma, Papillary↗