Biomedical subjects

S Muto

Publications and source records attributed to S Muto.

At least 19 recordsLinked to original sources

PubMed2006

Reversible hypocalcemic heart failure with T wave alternans and increased QTc dispersion in a patient with chronic renal failure after parathyroidectomy.

Despite the crucial role of calcium in myocardial contractility, hypocalcemia has very rarely been reported as a reversible cause of heart failure. In this article, we describe a case of a 51-year-old woman with advanced stages of chronic renal failure after parathyroidectomy who exhibited congestive heart failure, severe hypocalcemia, hypomagnesemia and hypokalemia. Severe hypocalcemia resulted from discontinuation of taking calcium supplements after parathyroidectomy and from reduced 1.25(OH)2D3 synthesis by damaged kidneys. The patient presented with reduced left ventricular ejection fraction (EF) and ECG abnormalities (T wave alternans and increased QTc dispersion), both of which improved after correction of serum calcium levels. Her serum levels of total calcium corrected for serum albumin, but not serum levels of magnesium or potassium, positively and negatively correlated with EF and QTc dispersion, respectively. In the present case, both heart failure and the ECG abnormalities are directly associated with hypocalcemia.

Calcium↗

PubMed2006

Complete remission of minimal-change nephrotic syndrome induced by apheresis monotherapy.

We report a case of a 17-year-old male with relapse of minimal-change nephrotic syndrome (MCNS), in whom apheresis monotherapy without steroids or immunosuppressants resulted in complete remission. The patient initially developed nephrotic syndrome in February 1998. The first renal biopsy confirmed the diagnosis of MCNS. The patient was also found to be a carrier of hepatitis B virus. Steroid therapy was started with oral prednisolone 60 mg/day. Complete remission was achieved in 3 months, and the steroid treatment was tapered off in May 2001. During the steroid tapering, temporal exacerbation of liver function was noted. In July 2002, the patient was admitted to our hospital again due to relapse of nephrotic syndrome. Second biopsy reconfirmed the diagnosis of MCNS. Since the serum titer of HBV was elevated, apheresis monotherapy was selected to avoid the risk of steroid-induced fulminant hepatitis. Four sessions of low-density lipoprotein apheresis (LDL-A) and 5 sessions of double-filtration plasmapheresis (DFPP) reduced the proteinuria from 9.2 g/day to 0.2 g/day over 38 days without any additional medication. Proteinuria remained suppressed below 0.2 g/day for more than 12 months and no exacerbation of liver function was observed up to the final follow-up in September 2003. The present case suggested the potential of apheresis monotherapy to induce and maintain complete remission of MCNS and an important role of circulating factors in the pathogenesis of MCNS.

Adolescent↗

PubMed2006

Fanconi's syndrome and distal (type 1) renal tubular acidosis in a patient with primary Sjögren's syndrome with monoclonal gammopathy of undetermined significance.

Tubulointerstitial nephritis is a well-recognized complication in primary Sjögrens syndrome. Fanconi's syndrome is a far less frequent complication compared with distal tubular dysfunction. We here describe a 49-year-old woman with primary Sjögren's syndrome. In 1997, she was diagnosed with primary Sjögren's syndrome with tubulointerstitial nephritis, and was then treated with oral prednisolone for the tubulointerstitial nephritis. In 2002, she was referred to our hospital because of progressive fatigue. At that time, biclonal spike on serum protein (IgG-kappa and IgA-kappa) and Bence-Jones protein in urine were found. Bone marrow aspiration showed 1.0% plasma cell infiltration. Thus, a diagnosis of monoclonal gammopathy of undetermined significance (MGUS) was made. In 2004, she was again admitted to our hospital because of mild renal dysfunction and hypokalemia. Laboratory evaluation showed inappropriate, alkaline urine in hyperchloremic metabolic acidosis and a positive urine anion gap, indicating the presence of distal (Type 1) renal tubular acidosis (RTA). The urine concentration defect was also found. Further studies revealed proximal tubular dysfunction, including renal glycosuria, generalized aminoaciduria, phosphaturia, uricosuria and proximal RTA. The kidney biopsy represented diffuse and severe tubulointerstitial nephritis with dense infiltrates of lymphocytes and IgA and K light chain-positive plasma cells. No findings of multiple myeloma or malignant lymphoma were observed. In conclusion, our patient had Sjögren's syndrome with MGUS and exhibited dysfunction of both proximal tubule (Fanconi's syndrome) and distal tubule, which may be attributed to diffuse tubulointerstitial nephritis.

Acidosis, Renal Tubular↗

PubMed2005

Arrangement of high-energy neutron irradiation field and shielding experiment using 4 m concrete at KENS.

An irradiation field of high-energy neutrons produced in the forward direction from a thick tungsten target bombarded by 500 MeV protons was arranged at the KENS spallation neutron source facility. In this facility, shielding experiment was performed with an ordinary concrete shield of 4 m thickness assembled in the irradiation room, 2.5 m downstream from the target centre. Activation detectors of bismuth, aluminium, indium and gold were inserted into eight slots inside the shield and attenuations of neutron reaction rates were obtained by measurements of gamma-rays from the activation detectors. A MARS14 Monte Carlo simulation was also performed down to thermal energy, and comparisons between the calculations and measurements show agreements within a factor of 3. This neutron field is useful for studies of shielding, activation and radiation damage of materials for high-energy neutrons, and experimental data are useful to check the accuracies of the transmission and activation calculation codes.

Computer Simulation↗

PubMed2005

Haematological data for Matsumoto Eosinophilic Shinshu rats as determined by an automated haematology analyser.

The Matsumoto Eosinophilic Shinshu (MES) rat originated from an inbred mutant colony of rats with spontaneous eosinophilia. As part of an investigation of the pathogenesis of the MES rat, we examined the haematology data for 106 males and 88 females and age-associated changes using an automated haematology analyser, flow cytometric analysis and morphological examination. The data at 10 weeks of age showed the MES rats had higher counts for eosinophils and neutrophils, slightly higher counts for lymphocytes, monocytes, basophils, and large unstained cells (LUCs), and slightly lower values for the erythrocytic parameters when compared with Sprague-Dawley (SD) rats. In data for MES rats aged 8 to 20 weeks, eosinophil counts increased with age up to 20 weeks together with some increased neutrophil counts. After 11 weeks of age, counts for lymphocytes, monocytes, basophils, and LUCs in the MES rats were also slightly increased. In female MES rats, flow cytometric analysis showed increased counts for pan-T+ cells, but blasts, abnormal granulocytes and lymphocytes were not detected morphologically. The MES rat characterized by the haematological findings could be a useful animal model for studies of hypereosinophilia.

Aging↗

PubMed2003

Sawtooth oscillation in current-carrying plasma in the large helical device.

Sawtooth oscillations have been observed in current-carrying helical plasmas by using electron-cyclotron-emission diagnostics in the Large Helical Device. The plasma current, which is driven by neutral beam injection, reduces the beta threshold of the sawtooth oscillation. When the central q value is increased due to the plasma current, the core region crashes, and, when it is decreased, the edge region crashes annularly. Observed rapid mixture of the plasma in the limited region suggests that these sawtooth crashes are reconnection phenomena. Unlike previous experiments, no precursor oscillation has been observed.

Journal Article↗

PubMed2003

Combined treatment with nafamostat mesilate and aspirin prevents heparin-induced thrombocytopenia in a hemodialysis patient.

We report on the management of a 36-year-old hemodialysis patient with heparin-induced thrombocytopenia (HIT, type II) and clot formation in extracorporeal circulation. Platelet aggregation test and measurement of anti-platelet factor 4/heparin complex antibody by enzyme-linked immunosorbent assay revealed to us that our patient had developed HIT. Instead of heparin, we used nafamostat mesilate (NM) as an anticoagulant during hemodialysis, but could not completely prevent HIT-induced thrombocytopenia or clot formation in the extracorporeal circuit. Combined use of NM and aspirin completely inhibited platelet aggregation, decrease in platelet count and clot formation in the extracorporeal circuit.

Adult↗

PubMed2002

Spallation ultracold-neutron production in superfluid helium.

The first ultracold-neutron (UCN) production in superfluid helium placed in a spallation neutron source is carried out. A UCN density of 0.7 UCN/cm(3), which can be used in experiments, is achieved for a proton-beam power of 78 W and a He-II temperature of 1.2 K. The present new UCN source is not limited by Liouville's theorem and extraction losses, which were serious problems in the previous sources. The present source has the possibility of extremely high-density UCN production compared with previous UCN sources.

Journal Article↗

PubMed2002

Island dynamics in the large-helical-device plasmas.

In the Large Helical Device plasma discharges, the size of an externally imposed island with mode number ( n/m = 1/1) decreases substantially when the plasma is collisionless ( nu(*)< approximately 1) and the beta is finite ( > approximately 0.1%) at the island location. For the collisional plasmas with finite beta, on the other hand, the size of the island increases. However, there is a threshold in terms of the vacuum island size below which the island enlargement is not seen.

Journal Article↗

PubMed2001

Observation of the "self-healing" of an error field island in the large helical device.

It was observed that the vacuum magnetic island produced by an external error magnetic field in the large helical device shrank in the presence of plasma. This was evidenced by the disappearance of flat regions in the electron temperature profile obtained by Thomson scattering. This island behavior depended on the magnetic configuration in which the plasmas were produced.

Journal Article↗

PubMed2001

Inhibition by green tea catechins of metabolic activation of procarcinogens by human cytochrome P450.

Catechins, major polyphenol constituents of green tea, are potent chemopreventive agents against cancers caused by chemical carcinogens in rodents. The effects of four epicatechin derivatives, epigallocatechin gallate (EGCG), epicatechin gallate (ECG), epigallocatechin (EGC) and epicatechin (EC), on the metabolic activation of benzo[a]pyrene (B[a]P), 2-amino-1-methyl-6-phenylimidazo-[4,5-b]pyridine (PhIP) and aflatoxin B(1) (AFB(1)) by human cytochrome P450 (CYP) were examined. B[a]P, PhIP and AFB(1) were activated by respective human CYP1A1, CYP1A2 and CYP3A4 expressed in the membrane fraction of genetically engineered Salmonella typhimurium (S. typhimurium) TA1538 cells harboring the human CYP and human NADPH-CYP reductase (OR), when the membrane fraction was added to S. typhimurium TA98. Galloylated catechins, ECG and EGCG inhibited the mutagenic activation potently, while EGC and EC showed relatively weak inhibitory effects. Catechins also inhibited the oxidations of typical substrates catalyzed by human CYPs, namely ethoxycoumarin O-deethylation by CYP1A1, ethoxyresorufin O-deethylation by CYP1A2 and midazolam 1'-hydroxylation by CYP3A4. The IC(50) values of catechins for the inhibition of human CYP were roughly the same as those seen in the mutagenic activation. EGCG inhibited other forms of human CYP such as CYP2A6, CYP2C19 and CYP2E1, indicating the non-specific inhibitory effects of EGCG toward human CYPs. Furthermore, EGCG inhibited human NADPH-cytochrome CYP reductase (OR) with a K(i) value of 2.5 microM. These results suggest that the inhibition of the enzyme activity of CYP is accounted for partially by the inhibition of OR.

Aflatoxin B1↗

PubMed2001

Biological activities of human mannose-binding lectin bound to two different ligand sugar structures, Lewis A and Lewis B antigens and high-mannose type oligosaccharides.

The biological activities of mannose-binding lectin (MBL) which binds to different ligands on mammalian cells were examined using two types of Colo205 cells, a human colon adenocarcinoma cell line: one naturally expressing Lewis A and Lewis B antigens as ligands for MBL (NT-Colo205), and the other modified to express high-mannose type oligosaccharides by treatment with benzyl-2-acetamide-2-deoxy-alpha-galactopyranoside and 1-deoxymannojirimycin (Bz+dMM-Colo205). Although the final lysis was not observed, the deposition of C4 and C3 was observed on both types of Colo205 cells after treatment with MBL and complements as a result of complement activation by MBL. MBL bound to Bz+dMM-Colo205 could also activate human peripheral blood leukocytes and induce superoxide production; however, MBL bound to NT-Colo205 could not. This may be explained by the lower affinity of MBL to Lewis A and Lewis B antigens than to high-mannose type oligosaccharides under physiological conditions, since MBL bound to NT-Colo205 was more easily released from the cell surface than that bound to Bz+dMM-Colo205 at 37 degrees C. These findings suggest that the difference in the affinity of MBL to its ligands could influence the expression of some biological activities of MBL.

Antibodies, Monoclonal↗

PubMed2001

Reduction of ion thermal diffusivity associated with the transition of the radial electric field in neutral-beam-heated plasmas in the large helical device.

Recent large helical device experiments revealed that the transition from ion root to electron root occurred for the first time in neutral-beam-heated discharges, where no nonthermal electrons exist. The measured values of the radial electric field were found to be in qualitative agreement with those estimated by neoclassical theory. A clear reduction of ion thermal diffusivity was observed after the mode transition from ion root to electron root as predicted by neoclassical theory when the neoclassical ion loss is more dominant than the anomalous ion loss.

Journal Article↗

PubMed2001

Protein kinase C and phosphatidylinositol 3-kinase independently contribute to P-glycoprotein-mediated drug secretion in the mouse proximal tubule.

We have recently reported that the apical membrane of the proximal tubule S2 segment from wild-type mice (WT mice) has the capacity for P-glycoprotein- (P-gp-) mediated drug efflux, whereas mice in which both mdr1a and mdr1b genes are disrupted (KO mice) do not. To examine the intracellular regulatory mechanisms of drug-transporting P-gp activity, we isolated and perfused proximal tubule S2 segments from WT and KO mice, and measured luminal efflux of the intracellular fluorescence of rhodamine 123, a fluorescent substrate of P-gp. The decay half-time of the intracellular fluorescence (t1/2) was regarded as an index of the drug-transporting P-gp activity. In the WT mice, the t1/2 was 36+/-5 s (n=35) during the basal period, and was significantly increased to 440+/-45 s by the luminal addition of verapamil (an inhibitor of P-gp). The addition of phorbol 12-myristate 13-acetate (PMA) [a protein kinase C (PKC) activator] to the bath increased t1/2, but 4alpha-phorbol (the inactive form of PMA) did not. The PMA-induced increase in t1/2 was further increased by the luminal addition of verapamil, and was partially inhibited by co-treatment with staurosporine or H-7 (inhibitors of PKC). Pretreatment with wortmannin or LY294002 [inhibitors of phosphatidylinositol 3-kinase (PI 3-kinase)] added to the bath also increased t1/2. The wortmannin- and LY294002-induced increase in t1/2 was also further increased by the luminal addition of verapamil. The effects of PMA on t1/2 were additive after cotreatment with wortmannin or LY294002. In the KO mice, t1/2 was 440+/-25 s (n=18) during the basal period, and was no longer affected by the addition of verapamil, staurosporine, H-7, wortmannin, or LY294002. Based on the use of pharmacological agents, we conclude that in the proximal tubule from WT mice, P-gp-mediated drug secretion occurs independently via PKC- and PI 3-kinase-dependent processes, whereas it is not present in KO mice, independently of PKC- and PI 3-kinase.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2001

The nucleus together with the cytosol generates patterns of specific cellular calcium signatures in tobacco suspension culture cells.

Plant cell suspension cultures respond to osmotic changes by alterations in levels of free cellular calcium. Using the aequorin recombinant method, we have measured the spatial and temporal characteristics of calcium signatures in the nucleus and the cytosol of BY-2 tobacco suspension cells challenged with hypo- or hyper-osmotic shock. We show here that the nuclear compartment contributes together with the cytosol to produce calcium signal patterns that discriminate hypo- from hyper-osmotic treatments, i.e. turgor from tension. We also demonstrate that calcium responses in the nucleus and the cytosol are differentially modulated by the strength and the nature of hyper-osmotic treatments. We conclude that qualitative and quantitative changes in the parameters of an external stimulus such as osmotic changes are converted into calcium signatures, distinctive in their temporal and subcellular characteristics, involving both the nucleus and the cytosol. Our results illustrate the versatility of calcium signaling in plant cells. In addition to the physiological 'address' of the cell, the compartmentation of the calcium signal is probably an important parameter in encoding response specificity.

Calcium Channel Blockers↗

PubMed2001

A serpin with M(r) 43,000 is a binding protein of M(r) 25,000 protein, a substrate for protein ser/thr kinase detected in Xenopus laevis oocytes.

In an attempt to get some clue as to the function of M(r) 25,000 protein, a protein Ser/Thr kinase substrate detected in Xenopus laevis oocytes [Hashimoto, E. et al. (1995) J. Biochem. 118, 453-460], the binding protein was surveyed using the (32)P-labeled protein by casein kinase II as a screening probe. When the cytosolic proteins from oocytes were transferred to a polyvinylidene fluoride membrane and incubated with the labeled protein, only one protein with M(r) 43,000 was visualized on autoradiography. This protein was purified to a nearly homogeneous state through several column chromatography steps. The amino acid sequence of the amino-terminal region of this protein identified it as a kind of serine protease inhibitor (serpin) [Holland, L.J. et al. (1992) J. Biol. Chem. 267, 7053-7059]. However, the M(r) 25,000 protein did not have any effect on the inhibitory action of this serpin on alpha-chymotrypsin. In addition, several binding proteins were also detected in the particulate fraction of oocytes, although the exact identity of these proteins is not clear at this time. These results suggest that the M(r) 25,000 protein may play some role(s) by interacting with these binding proteins in Xenopus oocytes.

Amino Acid Sequence↗

PubMed2001

A putative two pore channel AtTPC1 mediates Ca(2+) flux in Arabidopsis leaf cells.

The gene encoding voltage-gated channel with high affinity for Ca(2+) permeation has not been cloned from plants. In the present study, we isolated a full-length cDNA encoding a putative Ca(2+ )channel (AtTPC1) from Arabidopsis. AtTPC1 has two conserved homologous domains, both of which contain six transmembrane segments (S1-S6) and a pore loop (P) between S5 and S6 in each domain, and has the highest homology with the two pore channel TPC1 recently cloned from rat. The overall structure is similar to the half of the general structure of alpha-subunits of voltage-activated Ca(2+) channels from animals. AtTPC1 rescued the Ca(2+) uptake activity of a yeast mutant cch1. Sucrose-induced luminescence, which reflects a cytosolic free Ca(2+) increase in aequorin-expressing Arabidopsis leaves, was enhanced by overexpression of AtTPC1 and suppressed by antisense expression of it. Sucrose-H(+) symporters AtSUC1 and 2, which depolarize membrane potential of cells receiving sucrose, also depressed a Ca(2+) increase by their antisense expression. These results suggest that AtTPC1 mediates a voltage-activated Ca(2+ )influx in Arabidopsis leaf cells.

Aequorin↗

PubMed2001

Sugar-induced increase in cytosolic Ca(2+) in Arabidopsis thaliana whole plants.

Using Ca(2+)-dependent photoprotein aequorin-transformed Arabidopsis thaliana, sugar-induced increase in cytosolic free Ca(2+ )concentration ([Ca(2+)](cyt))( )was investigated by luminescence imaging technique. When 0.1 M sucrose was fed to roots of autotrophically grown intact whole plants whose roots had been incubated overnight with coelenterazine to reconstitute aequorin systemically, strong and transient (within 20 s) luminescence was observed in the roots; that luminescence was followed by weak luminescence moving from the lower leaves to the upper leaves. The moving rate of luminescence was roughly comparable to that of [(14)C]sucrose. Application of 0.1 M glucose or fructose induced transient luminescence in excised leaves. No such luminescence was observed in heterotrophically grown (with sucrose) whole plants or in excised tissues. mRNA levels of sucrose-H(+) symporter genes AtSUC1 and AtSUC2 were higher in autotrophic plants than in heterotrophic plants. These results indicate that influx of transported sucrose together with H(+) into the mesophyll cells of autotrophic plants may depolarize the membrane potential, and subsequently activate a voltage-gated Ca(2+) channel on the plasma membrane, resulting in a [Ca(2+)](cyt) increase. The [Ca(2+)](cyt) increase might initiate Ca(2+ )signaling leading to the expression of genes related to biosynthesis of storage carbohydrates. Hexoses, when applied, might also be involved in the [Ca(2+)](cyt) increase mediated by monosaccharide-H(+) co-transporters.

Arabidopsis↗