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S Watanabe

Publications and source records attributed to S Watanabe.

At least 127 records · Page 7Linked to original sources
PubMed2001

Mesenteric lipoma: report of a case with emphasis on US findings.

Mesenteric lipoma (ML) is a relatively rare disease that has been very infrequently reported. We present the clinical data and medical imaging results of an asymptomatic case with ML incidentally detected by sonography (US). On US the lesion was imaged as a well-demarcated hypoechoic mass with multiple linear echoes. The mass also changed location under probe compression. The lesion was imaged as a clearly demarcated non-enhanced homogeneous fat-density mass on CT. Color Doppler US and angiography confirmed the avascular nature of the mass. Knowledge of the US findings in this case is useful for the diagnosis of ML.

Adult↗
PubMed2001

Glu375Gln and Asp225Val mutants: about the nature of the covalent linkages between heme group and apo-Protein in bovine lactoperoxidase.

In analogy with studies previously reported for myeloperoxidase (Kooter, I. M.; Moguilevsky, N.; Bollen, A.; Van der Veen, L. A.; Otto, C.; Dekker, H. L.; Wever, R. J. Biol. Chem. 1999, 274, 26794), we examined for bovine lactoperoxidase the effect of mutation of Asp225 and Glu375, the residues thought to be responsible for the covalent binding of the heme group to the apoprotein. Starting from the plasmid encoding rbLPO (Watanabe, S.; Varsalona, F.; Yoo, Y.; Guillaume, J. P.; Bollen, A.; Shimazaki, K.; Moguilevsky, N. FEBS Letters 1998, 441, 476), which was engineered to carry mutations in correspondence of those residues, the mutants Asp225Val and Glu375Gln were expressed in CHO cells and their products purified and characterized. Unequivocal evidence about the existence of ester linkages as well as their relative contribution to the specific spectroscopic and catalytic properties of bLPO is here discussed.

Amino Acid Substitution↗
PubMed2001

Involvement of cholinergic and glutamatergic functions in working memory impairment induced by interleukin-1beta in rats.

Interleukin-1beta at doses of 32 and 100 ng/side, injected bilaterally into the dorsal hippocampus of rats, significantly increased the working memory errors in a three-panel runway setup, whereas interleukin-1beta at doses affecting working memory errors had no effect on the number of errors in the first trial or the latency. The increase in working memory errors induced by intrahippocampal administration of 100 ng/side interleukin-1beta was significantly decreased by concurrent injection (300 ng/side) of the interleukin-1 receptor antagonist. The cholinesterase inhibitor physostigmine at a dose of 3.2 microg/side and D-cycloserine (1.0 and 10 microg/side), which is a partial agonist acting at the glycine binding site of the NMDA receptor/channel complex, reduced the increase in working memory errors induced by 100 ng/side interleukin-1beta. These results suggest that interleukin-1beta causes disruptions of septohippocampal cholinergic and glutamatergic transmission via its high-affinity receptor, which underlie the impairment of working memory.

Analysis of Variance↗
PubMed2001

Crystallization and preliminary X-ray diffraction studies of monomeric isocitrate dehydrogenase by the MAD method using Mn atoms.

NADP(+)-dependent isocitrate dehydrogenase (E.C. 1.1.1.42; IDH) is an enzyme of the Krebs cycle and catalyzes the oxidative decarboxylation reaction from DL-isocitrate to alpha-ketoglutarate, with a concomitant reduction of the coenzyme NADP(+) to NADPH. Single crystals of monomeric IDH from Azotobacter vinelandii in complex with DL-isocitrate and Mn(2+) were obtained by the hanging-drop vapour-diffusion method at room temperature. One crystal diffracted to a resolution of 2.9 A and was found to belong to the orthorhombic system; the space group was determined to be P2(1)2(1)2(1), with unit-cell parameters a = 108.4, b = 121.7, c = 129.7 A. The asymmetric unit contains two molecules of monomeric IDH, corresponding to a V(M) value of 2.66 A(3) Da(-1). The crystals were frozen in a capillary by a flash-cooling technique and MAD data were collected using Mn atoms as anomalous scatterers on beamline BL41XU at SPring-8, Japan. The positions of two Mn atoms binding to two independent IDH molecules were located from Bijvoet difference Patterson maps.

Azotobacter vinelandii↗
PubMed2001

Total energy distribution of field-emitted electrons from Al(100) surface with single-atom terminated protrusion.

We have analyzed field electron emission from Al(100) surfaces with a single-atom terminated protrusion on the basis of the density functional theory combined with real space scattering theory. We have obtained multiple peaks in total energy distribution of emission current from such a pure-metallic protrusion. Furthermore, we have also found that multiple peaks become pronounced as the size of a protrusion becomes larger, which explains the discrepancy among experiments. All the above results can be understood from two factors, the existence of localized states at the topmost Al atom and the potential barrier reduction in front of the topmost atom.

Journal Article↗
PubMed2001

Long-lasting memory of sounds combined with reward in rats.

We investigated the effects of sound stimuli combined with reward on the subsequent sound discrimination. Water-deprived rats were exposed to one of two sounds (S+ or S-) in a trial, and licking a spout only during the presentation of S+ was rewarded with water. The percentage of trials in which licking occurred was calculated separately for S+ and S-, and sound discrimination was estimated from the difference in the percentage. S+ and S- were significantly discriminated during an 8 h period. In the second test after 1-2 weeks, sound discrimination for the same S+ and S- was significantly better than that for the S+ of the previous S- and S- of the previous S+. These findings indicate that the memory of the sounds combined with reward in the first test was maintained for 1-2 weeks.

Acoustic Stimulation↗
PubMed2001

STM images apparently corresponding to a stable structure: considerable fluctuation of a phase boundary of the Si(111)-(square root of (3) x square root of (3))-Ag surface.

We study scanning tunneling microscopy (STM) images near a phase boundary of the Si(111)- (square root of (3) x square root of (3))-Ag surface by using Monte Carlo simulations based on results of first-principles calculations. The boundary is found to fluctuate from snapshot to snapshot, and the feature of the simulated STM images differs distinctly from the observed one with a straightly extending honeycomb pattern of bright spots. Remarkably, statistical averages of the simulated images reproduce the observed feature. This study gives a warning of our tendency to relate STM images revealing clear arrangement of bright spots with some stable structure.

Journal Article↗
PubMed2001

Cell cycle-dependent interaction of Mad2 with conserved Box1/2 region of human granulocyte-macrophage colony-stimulating factor receptor common betac.

Box1 and 2 (box1/2) are conserved cytoplasmic motifs located in the membrane proximal region of cytokine receptors, including the human granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor common betac. Deletion of box1/2 abrogated all the examined activities of GM-CSF, and this phenomenon is explained by the loss of binding by Jak2. To test if a molecule other than Jak2 interacting with the box1/2 region plays a role in GM-CSF receptor signal transduction, we screened for molecules interacting with the box1/2 region by a pull-down assay using recombinant purified protein of GST fused with the betac box1/2 region and a Ba/F3 cell lysate. The mouse homologue of Mad2 protein, which plays an important role in the M phase of the cell cycle, was revealed to associate with the box1/2 region specifically. Peptides corresponding to the box1 sequence also bound to Mad2, and mutation of the box1 decreased the Mad2 interaction. Deletion analysis indicated that interaction with box1/2 occurred through the C-terminal portion of Mad2. Mad2 is known to change affinity for binding partners cell cycle dependently. Binding affinity of Mad2 to box1/2 increased in the late M phase, suggesting the possibility that GM-CSF participates in regulation of the M phase check point through interaction with Mad2.

Amino Acid Sequence↗
PubMed2001

Regulatory roles of adenylate cyclase and cyclic nucleotide phosphodiesterases 1 and 4 in interleukin-13 production by activated human T cells.

We studied the activities of 3',5'-adenosine-cyclic monophosphate (cAMP)- synthesizing adenylate cyclase (AC) and cAMP-hydrolyzing cyclic nucleotide phosphodiesterase (PDE) in phytohemagglutinin (PHA)- or anti-CD3 plus anti-CD28-stimulated human T cells, and examined their roles in interleukin-13 (IL-13) production. The AC inhibitor MDL 12,330A [cis-N-(2-phenylcyclopentyl)azacyclotridec-1-en-2-amine hydrochloride] completely blocked PHA- or anti-CD3/CD28-induced IL-13 production. The PDE 1 inhibitor 8-methoxymethyl-3-isobutyl-1-methylxanthine or the PDE4 inhibitor rolipram partially inhibited IL-13 production, and the addition of both resulted in 100 or 85% inhibition in PHA- or anti-CD3/CD28-stimulated T cells, respectively. AC in T cells was transiently activated 5 min after stimuli, followed by the transient activation of PDE4 at 30 min. PDE1 activity, undetectable in resting T cells, was detected 3 hr after stimuli, and then increased gradually. Although PDE1-, 2-, 3-, and 4-independent PDE activity was low (< or = 15% of total), it began to increase 3 hr after anti-CD3/CD28; the increase was blocked by PDE7 antisense oligonucleotide, and such an increase was not induced by PHA. PHA or anti-CD3/CD28 induced PDE1B mRNA expression, undetectable in resting T cells. PDE4 mRNA level in T cells was not altered by either stimulus. PDE7 mRNA expression was detected in resting T cells, and was enhanced by anti-CD3/CD28, but not by PHA. The cAMP level of T cells increased 5 min after stimuli, returned to the basal level at 2 hr, and then continued to decrease. These results suggest that PHA or anti-CD3/CD28 initially (< or = 5 min) increases cAMP in T cells via AC, then reverses the increase via PDE4 (< or = 2 hr), and in the later phase (> 2 hr) further decreases cAMP via PDE1. Both the time-dependent increase and decrease of cAMP may be required for IL-13 production.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2001

Endogenous cannabinoid, 2-arachidonoylglycerol, attenuates naloxone-precipitated withdrawal signs in morphine-dependent mice.

In the present study, we examined the effects of endogenous ligand 2-arachidonoylglycerol (2-AG) on naloxone-precipitated withdrawal in morphine-dependent mice, in comparison with that of two cannabinoid agonists, an ingredient of Cannabis sativa Delta(8)-tetrahydrocannabinol (Delta(8)-THC) and the synthetic cannabinoid CB1 receptor agonist HU-210. 2-AG at a dose of 10 microg per mouse (i.c.v.) significantly inhibited both jumping and forepaw tremor as signs of withdrawal following naloxone challenge in morphine-dependent mice. Furthermore, both Delta(8)-THC and HU-210 significantly attenuated these symptoms of withdrawal in morphine-dependent mice. Therefore, it is suggested that inactivation of the endogenous cannabinoid system is related to the induction of withdrawal syndrome in morphine-dependent mice. Moreover, hyperlocomotor activity in morphine-dependent mice was markedly increased by Delta(8)-THC 10 mg/kg, which had no effect in naive mice. This finding suggested that in morphine dependence, upregulation of cannabinoid CB1 receptors occurred. Non-psychoactive CB1 receptor agonists or accelerators of endocannabinoid synthesis may be potential as therapeutic drugs for opiate withdrawal symptoms.

Animals↗
PubMed2001

Structural and cohesive properties of a C60 monolayer.

We have explored the cohesive property of a monolayer of C (60) molecules (ML- C (60)) by means of total energy calculations with the density-functional theory. The total energy curve calculated for ML- C (60), which is obtained as a function of the lattice constant, has two minima and shows a hysteresis in the compression-tension stroke. These two minima in energy correspond to the different structural phases of ML- C (60): one is a monomer phase and the other is a polymer one. The energy band gap within the framework of the local density approximation varies from 1 eV (semiconducting phase) to 0 eV (metallic phase) with external pressure and without structural transition from the monomer phase to the polymer one.

Carbon↗
PubMed2001

Direct measurement of the pion valence-quark momentum distribution, the pion light-cone wave function squared.

We present the first direct measurements of the pion valence-quark momentum distribution which is related to the square of the pion light-cone wave function. The measurements were carried out using data on diffractive dissociation of 500 GeV/c pi(-) into dijets from a platinum target at Fermilab experiment E791. The results show that the /q&q> light-cone asymptotic wave function describes the data well for Q2 approximately 10 (GeV/c)(2) or more. We also measured the transverse momentum distribution of the diffractive dijets.

Journal Article↗
PubMed2001

Observation of color-transparency in diffractive dissociation of pions.

We have studied the diffractive dissociation into dijets of 500 GeV/c pions scattering coherently from carbon and platinum targets. Extrapolating to asymptotically high energies (where t(min)-->0), we find that when the per-nucleus cross section for this process is parametrized as sigma = sigma0Aalpha, alpha has values near 1.6, the exact result depending on jet transverse momentum. These values are in agreement with those predicted by theoretical calculations of color-transparency.

Journal Article↗
PubMed2001

CREB-H: a novel mammalian transcription factor belonging to the CREB/ATF family and functioning via the box-B element with a liver-specific expression.

The expression of liver-specific genes is regulated by unequivocally allocated transcription factors via proper responsible elements within their promoters. We identified a novel transcription factor, CREB-H, and found that its expression was restricted in the liver among 16 human tissues tested. A region of CREB-H exhibited significant homology to the basic leucine zipper (b-Zip) domain of members of the CREB/ATF family: mammalian LZIP and Drosophila BBF-2 that binds to box-B, a Drosophila enhancer modulating the fat-body-specific gene expression. CREB-H contained a hydrophobic region representing a putative transmembrane domain, like LZIP. Constructing a variety of CREB-H fusion proteins with the GAL4 DNA-binding domain disclosed that CREB-H functioned as a transcriptional activator and its N-terminal 149 amino acids accounted for the activation ability. Gel mobility sift assays revealed that CREB-H did not bind to the C/EBP, AP-1 and NF-kappaB elements but specifically bound to CRE and the box-B element. Luciferase reporter assays demonstrated that like BBF-2, CREB-H activated transcription via the box-B element and that a deletion of the putative transmembrane domain increased the activation of reporter expression significantly. Furthermore, a fusion protein of GFP and full-length CREB-H was localized in reticular structures surrounding the nucleus, whereas a fusion protein of GFP and a deletion mutant lacking the putative transmembrane domain was mainly in the nucleus. These findings suggest that CREB-H plays an important role in transcriptional regulation of genes specifically expressed in the liver, and that the putative transmembrane domain may be associated with modulation of its function as the transcriptional activator.

Activating Transcription Factors↗
PubMed2001

Search for rare and forbidden Charm Meson decays D0 --> Vl+l- and hhll.

We report results of a search for flavor-changing neutral current (FCNC), lepton flavor, and lepton-number violating decays of the D0 (and its antiparticle) into three and four bodies. Using data from Fermilab charm hadroproduction experiment E791, we examine modes with two leptons (muons or electrons) and a rho(0), K( *0), or straight phi vector meson or a nonresonant pi(pi), Kpi, or KK pair of pseudoscalar mesons. No evidence for any of these decays is found. Therefore, we present branching-fraction upper limits at 90% confidence level for the 27 decay modes examined (18 new).

Journal Article↗