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T Murayama

Publications and source records attributed to T Murayama.

At least 91 records · Page 5Linked to original sources
PubMed1999

Further characterization of the type 3 ryanodine receptor (RyR3) purified from rabbit diaphragm.

We characterized type 3 ryanodine receptor (RyR3) purified from rabbit diaphragm by immunoaffinity chromatography using a specific antibody. The purified receptor was free from 12-kDa FK506-binding protein, although it retained the ability to bind 12-kDa FK506-binding protein. Negatively stained images of RyR3 show a characteristic rectangular structure that was indistinguishable from RyR1. The location of the D2 segment, which exists uniquely in the RyR1 isoform, was determined as the region around domain 9 close to the corner of the square-shaped assembly, with use of D2-directed antibody as a probe. The RyR3 homotetramer had a single class of high affinity [3H]ryanodine-binding sites with a stoichiometry of 1 mol/mol. In planar lipid bilayers, RyR3 displayed cation channel activity that was modulated by several ligands including Ca2+, Mg2+, caffeine, and ATP, which is consistent with [3H]ryanodine binding activity. RyR3 showed a slightly larger unit conductance and a longer mean open time than RyR1. Whereas RyR1 showed two classes of channel activity with distinct open probabilities (Po), RyR3 displayed a homogeneous and steeply Ca2+-dependent activity with Po approximately 1. RyR3 was more steeply affected in the channel activity by sulfhydryl-oxidizing and -reducing reagents than RyR1, suggesting that the channel activity of RyR3 may be transformed more precipitously by the redox state. This is also a likely explanation for the difference in the Ca2+ dependence of RyR3 between [3H]ryanodine binding and channel activity.

Animals↗
PubMed1999

Modifications of Ca2+ mobilization and noradrenaline release by S-nitroso-cysteine in PC12 cells.

The effects of nitrogen monoxide (NO)-related compounds on cytosolic free Ca2+ concentrations ([Ca2+]i) and noradrenaline (NA) release in neurosecretory PC12 cells were investigated. The addition of S-nitroso-cysteine (SNC) stimulated [Ca2+]i increases from an intracellular Ca2+ pool continuously in a concentration-dependent manner. Other NO donors, which stimulate cyclic GMP accumulation, did not cause [Ca2+]i increases. After treatment with 0.2 mM SNC, transient increases in [Ca2+]i from the Ca2+ pool induced by caffeine were completely abolished. The addition of N-ethylmaleimide (NEM) caused sustained [Ca2+]i increases from the intracellular Ca2+ pool. Furthermore, caffeine did not stimulate further [Ca2+]i increases in PC12 cells pretreated with NEM. These findings suggest that SNC and NEM predominantly interact with a caffeine-sensitive Ca2+ pool. The addition of dithiothreitol (DTT) to 0.4 mM SNC-stimulated cells reduced [Ca2+]i to basal levels, and the addition of DTT to NEM-stimulated cells locked [Ca2+]i at high levels. The stimulatory effects of SNC but not NEM were not abolished by pretreatment with DTT. These findings suggest that modification of the oxidation status of the sulfhydryl groups on the caffeine-sensitive receptors by SNC or NEM regulates Ca2+ channel activity in a reversible manner. SNC did not stimulate NA release by itself but did inhibit ionomycin-stimulated NA release. In contrast, NEM stimulated NA release in the absence of extracellular CaCl2 and further enhanced ionomycin-stimulated NA release. Ca2+ mobilization by SNC from the caffeine-sensitive pool was not a sufficient factor, and other factors stimulating NA release may be negatively regulated by SNC.

Adenosine Triphosphate↗
PubMed1999

Intraperitoneal administration of anti-c-fms monoclonal antibody prevents initial events of atherogenesis but does not reduce the size of advanced lesions in apolipoprotein E-deficient mice.

BACKGROUND: Atherosclerosis results from complex inflammatory-fibroproliferative responses. To elucidate the central role of macrophage and macrophage-colony stimulating factor (M-CSF) during atherogenesis, we used a new strategy to administer to adult apolipoprotein E (apoE)-deficient mice a monoclonal antibody (AFS98) raised against c-fms, the receptor of M-CSF. METHODS AND RESULTS: When 6-week-old apoE-deficient mice were fed a high-fat diet and injected with 2 mg of AFS98 intraperitoneally on alternate days for 6 weeks, accumulation of macrophage-derived foam cells in the aortic root was suppressed by 70% compared with that in controls. This preventive effect was associated with neither remarkable decrease of the number of circulating monocytes nor systemic growth retardation. In contrast, when apoE-deficient mice that had been fed a high-fat diet from 6 weeks of age were given AFS98 from 12 to 18 weeks of age, a minimal protective effect on lesion size was observed. CONCLUSIONS: These results suggest that (1) macrophage and M-CSF/c-fms play an essential role in the arterial wall during development of the fatty streak lesion and (2) blockade of the M-CSF/c-fms pathway could act as protection from at least early atherogenesis but could have a less preventive effect on maintenance of the advanced lesions.

Animals↗
PubMed1999

Soluble fas ligand in natural killer cell lymphoma.

We measured serum soluble Fas ligand (sFasL) in a patient with natural killer cell lymphoma, and investigated relationship between sFasL and liver dysfunction. An elevated level of sFasL was decreased after local radiation therapy, and liver function improved. When lymphoma relapsed, liver dysfunction reappeared and the level of sFasL increased parallelly. Lymphoma cells expressed mRNA of FasL. This suggested that this liver dysfunction was induced by some remote effectors, and sFasL was one of candidates of these effectors.

Adult↗
PubMed1999

The effect of cyclic AMP on expression of the major immediate-early genes and replication of human cytomegalovirus in human central nervous system cell lines.

The effect of dibutyryl cyclic AMP (dbcAMP) on interaction of human cytomegalovirus (HCMV) with human central nervous system cell lines was examined. Activation of the major immediate-early (IE) promoter (MIEP) of HCMV by dbcAMP was observed in human neuroblastoma IMR-32 cells, but not in glioma 118MGC and astrocytoma U373-MG cells. The 19 bp repeat element in the enhancer of the MIEP was most likely to be the cis-element that responded to dbcAMP in IMR-32 cells as we expected. In IMR-32 cells activation of the MIEP led to enhanced synthesis of the major IE proteins and infectious HCMV.

Astrocytoma↗
PubMed1999

Ryanodine receptor isoforms in excitation-contraction coupling.

Three genomically distinct isoforms of RyR are now known. RyR1 homologue is the primary isoform in skeletal muscles, whereas in cardiac muscles it is RyR2 homologue. RyR3 homologue occurs ubiquitously in many cells, but the biological function is little known, partly because of its minuscule amount in mammalian cells. The difference among RyR isoforms may not be so great in CICR activity, in other words, in the interaction of RyR isoforms with Ca2+, adenine nucleotides and caffeine. Species specificity among RyR1 homologues may be more important in the apparent difference between RyR1 and RyR3 homologues. CICR is likely to be the dominant underlying mechanism for E-C coupling in the cardiac muscle and probably in cells other than the skeletal muscle where the significance of CICR is controversial in physiological contraction. In E-C coupling of skeletal muscle (DICR), the reciprocal tight interactions between DHPR and RyR1 are critically required. The alpha 1 subunit of DHPR was only the main target of our current interests in the interaction with RyR1; the involvement of auxiliary subunits of alpha 2/delta and beta subunits and their mutual interactions, however, are also important. DICR and CICR in RyR1 share common properties of stimulation by concentrated solutes and modulation by luminal calcium or Ca2+, suggesting that the main difference between the two Ca2+ release mechanisms may be in the gating mechanism of the channel. Further investigations are required to understand molecular interactions during E-C coupling.

Adenine Nucleotides↗
PubMed1999

Effects of T-588, a novel cognitive enhancer, on ADP-ribosylation of G(s alpha) by cholera toxin and cyclic AMP accumulation in rat cerebral cortex.

We investigated the effects of R(-)-1-(benzo[b]thiophen-5-yl)-2-[2-(N,N-diethylamino)ethoxy]ethan ol hydrochloride (T-588), a novel cognitive enhancer, on trimeric GTP-binding proteins (G proteins) and cyclic AMP accumulation in rat cerebral cortex. T-588 (0.1-1.0 mM) inhibited the ADP-ribosylation of alpha subunit of Gs in a concentration-dependent manner. Auto-ADP-ribosylation of CTX was not inhibited by T-588. The stimulatory effect of guanosine 5'-(3-O-thio)triphosphate (GTPgammaS) on CTX-catalyzed ADP-ribosylation was attenuated by adding T-588 in assay mixture. ADP-ribosylation of Gi/Go by pertussis toxin was slightly inhibited by T-588. Isoproterenol-stimulated cyclic AMP accumulation was inhibited by adding 3 mM T-588 to rat cerebral cortical slices. Next, we investigated the effects of isoproterenol and T-588 on GTPgammaS binding. Membranes were first incubated with or without isoproterenol and T-588 in the presence of 0.2mM GTPgammaS, then cholate extract preparations were prepared from the washed membranes. Interestingly, the [32P]ADP-ribosylation of G(s alpha) was enhanced not only by isoproterenol but also by T-588. Although the obtained results are apparently inconsistent, T-588 seems to interact with G proteins, specifically Gs.

Adenosine Diphosphate Ribose↗
PubMed1999

Inhibition of noradrenaline release from PC12 cells by the long-term treatment with cholera toxin.

Guanine nucleotide-binding (G) proteins are required for intracellular vesicular transport and endocytosis. In this study, we investigated the effects of short-term (2 h) and long-term (24 h) treatment with cholera toxin (CTX), which ADP-ribosylates proteins having arginine residues such as the alpha subunit of Gs (G(s alpha)), on exocytosis from the neurosecretory rat pheochromocytoma PC 12 cell line. Short-term treatment with CTX stimulated the accumulation of cyclic AMP, and synergistically enhanced both extracellular Ca2+-dependent [3H]noradrenaline (NA) releases (induced by high K+ and ATP) and Ca2+-independent release (induced by mastoparan, a peptide in wasp venom). Long-term treatment with CTX for 24h inhibited Ca2+-dependent and -independent stimulated [3H]NA release. The inhibitory effect of long-term CTX treatment was not derived from a cyclic AMP-dependent system, because (1) H-89, an inhibitor of protein kinase A, had no effect on the inhibition induced by CTX, (2) the long-term treatment with forskolin did not show an inhibitory effect. [32P]ADP-ribosylation of G(s alpha) and its immunoreactivity with anti-G(s alpha) antiserum in the crude membrane fraction was inhibited in the long-term CTX-treated cells, but not in the long-term forskolin-treated cells. [32P]ADP-ribosylation of G(s alpha) in the membrane fraction of short-term CTX-treated cells was approximately 90% of the level in the control cells. These findings suggest that CTX stimulates [3H]NA release via a cyclic AMP-dependent system in the short-term, and that long-term CTX treatment inhibited its release, maybe via ADP-ribosylation of CTX-sensitive proteins such as G(s alpha).

Adenosine Diphosphate Ribose↗
PubMed1999

Levels of soluble FasL and FasL gene expression during the development of graft-versus-host disease in DLT-treated patients.

Three patients with different clinical symptoms of graft-versus-host disease (GVHD) who had received donor lymphocyte transfusion (DLT) for the treatment of relapsed leukaemia after an allogeneic bone marrow transplantation (BMT) from HLA-matched sibling donors were analysed for the presence of soluble FasL (sFasL) in the sera and for the expression of the Fas ligand (FasL) gene in the peripheral blood mononuclear cells (PBMNC). Two patients who demonstrated liver damage with increased levels of serum bilirubin showed significantly increased levels of serum sFasL. The increase in the sFasL level was observed prior to the increase in the bilirubin during the clinical courses of both patients. The high dose of methyl predonisolone administered to one of these patients greatly reduced the levels of sFasL in the serum. The bilirubin levels were also reduced thereafter. The third patient (without liver damage) did not show any increase in the serum sFasL level. The expression of the FasL gene in the PBMNC of these three patients was examined. All three patients showed increased levels of the FasL gene expression during their clinical courses. However, only one patient showed a parallel alteration of FasL gene expression with sFasL in the serum. These cases provide evidence that the Fas/FasL system is closely associated with human GVHD, especially in the development of liver GVHD.

Adult↗
PubMed1999

A case of urethral recurrence found 15 years after radical cystectomy.

PURPOSE: A case of a urethral recurrence found 15 years after radical cystectomy is reported. METHODS/RESULTS: A 78-year-old man, who had undergone radical cystectomy at age 63, presented with urethral bleeding and positive cytology in urethral washing. The urethra was surgically resected. Pathologic examination revealed transitional cell carcinoma located in the distal and mid portion of the penile urethra. CONCLUSION: Evidence suggested that urethral recurrence resulted from the implantation from the primary bladder tumor; in addition, the urethral neoplasm had scarcely grown in the penile urethra for 15 years.

Cystectomy↗
PubMed1999

Contractile responses to alpha1-adrenoceptor agonists in isolated human male and female urethra.

OBJECTIVE: To investigate the contractile responses mediated through alpha1-adrenoceptors in human urethra and to evaluate the effectiveness of NS-49 [(R)-(-)-3'-(2-amino-1-hydroxyethyl)-4'-fluoromethanesulphonanilide++ + hydrochloride], a novel alpha1-adrenoceptor agonist, against contraction of the human urethra. MATERIALS AND METHODS: The contractile responses were assessed in 10 male prostatic urethrae and six female urethrae. Antagonism was evaluated in the urethra using phenylephrine, a nonselective alpha1-adrenoceptor agonist, cumulatively applied > 20 min after applying 0.1 micromol/L prazosin or 0.1 micromol/L 5-methylurapidil, a selective alpha1A-adrenoceptor antagonist. Agonism was determined in both male and female urethrae to obtain the concentration-response curve for the agonist. RESULTS: Phenylephrine caused both male and female urethrae to contract, and showed high potency and efficacy. Prazosin antagonized these contractions with low affinity (apparent pKB of 8.30 in male urethrae). 5-Methylurapidil, also antagonized the contractions with low affinity (apparent pKB of 7.88 in male urethrae). Noradrenaline and phenylephrine caused both male and female urethrae to contract, with high potency and efficacy. A novel and selective alpha1A-and alpha1L-adrenoceptor agonist, NS-49, induced contractile responses with high potency and moderate efficacy, whereas methoxamine induced contractions with low potency and moderate efficacy. Norephedrine was a very weak contractile agonist. CONCLUSION: In the human urethra, phenylephrine-induced contractions were mediated through alpha1L-adrenoceptors and not through alpha1A-adrenoceptors. Contractions of the human urethra induced by NS-49 were also mediated mainly through alpha1L-adrenoceptors, with high potency and moderate efficacy. NS-49 may therefore be useful for the treatment of urinary stress incontinence, with minimal side-effects because it has subtype selectivity.

Adrenergic alpha-Agonists↗
PubMed1999

Response to granulocyte colony-stimulating factor in an autoimmune neutropenic adult.

Clinical value of granulocyte colony-stimulating factor (G-CSF) for autoimmune neutropenia (AIN) has not been well established. We experienced an adult case of AIN which showed an excellent response to G-CSF. A 75-year-old female was admitted with high-grade fever. Her neutrophil count was remarkably low (neutrophil 0.09 x 10(9)/l). Antigranulocyte autoantibody was demonstrated in her serum by an immunofluorescence method and she was diagnosed as AIN. Administration of G-CSF (filgrastim 5 microgram/kg) gave a rapid increase of neutrophils (from 0.11 x 10(9)/l to 2.10 x 10(9)/l on the second day), which has enabled us to preserve the use of G-CSF for emergency, that is, for overt serious infection.

Aged↗
PubMed1999

Effect of clarithromycin regimen for Mycobacterium avium complex pulmonary disease.

We have investigated the efficacy of a clarithromycin-containing four-drug regimen for Mycobacterium avium complex (MAC) pulmonary disease in 46 patients without acquired immunodeficiency syndrome (AIDS). The patients were 14 males and 32 females with a mean age of 60.9 +/- 11.5 yr. Patients received 10 mg/kg/d of clarithromycin plus ethambutol, rifampin, and initial kanamycin and subsequent quinolone for 24 mo. Seven patients (15.2%) were dropped in the first 6 mo. Among 39 patients who received more than 6 mo of therapy, 28 patients (71.8%) converted their sputa to negative: 26 of 31 patients (83.9%) infected with clarithromycin-susceptible strains and two of eight patients (25.0%) with resistant or intermediate strains. The timing of sputum conversion was 3.6 +/- 1.9 mo, with a range of 2 to 9 mo. The conversion rate was significantly lower in patients who were infected with clarithromycin-resistant or intermediate strains, who had had prior therapy (55.0% versus 89.5%), or who were acid-fast bacilli (AFB) smear-positive at entry (60.7% versus 100%). The age and sex of patients, the species of pathogen (M. avium or M. intracellulare), type and extent of the disease, and the use of kanamycin did not significantly affect the conversion rate. Although the regimen was efficacious for newly treated patients, frequent adverse reactions and a low conversion rate of sputum in retreated patients are problems that remain to be solved.

Adult↗
PubMed1999

[Two cases of interstitial cystitis complicated with migraine].

Two cases of interstitial cystitis complicated with migraine and atopic tendency are reported. In the bladder tissue of the two cases, mast cells were increased and in one case which was observed with immunohistochemical staining, most of the mast cells among muscle layers were chymase-positive mast cells. We considered that the degranulation of mast cells was related with the cause of interstitial cystitis and migraine.

Aged↗
PubMed1999

Comparison of properties of Ca2+ release channels between rabbit and frog skeletal muscles.

Biochemical investigation of Ca2+ release channel proteins has been carried out mainly with rabbit skeletal muscles, while frog skeletal muscles have been preferentially used for physiological investigation of Ca2+ release. In this review, we compared the properties of ryanodine receptors (RyR), Ca2+ release channel protein, in skeletal muscles between rabbit and frog. While the Ryr1 isoform is the main RyR of rabbit skeletal muscles, two isoforms, alpha- and beta-RyR which are homologous to Ryr1 and Ryr3 isoforms in mammals, respectively, coexist as a homotetramer in a similar amount in frog skeletal muscles. The two isoforms in an isotonic medium show very similar property in [3H]ryanodine binding activity which is parallel to Ca2+ -induced Ca2+ release (CICR) activity, and make independent contributions to the activities of the sarcoplasmic reticulum. CICR and [3H]ryanodine binding activities of rabbit and frog are qualitatively similar in stimulation by Ca2+, adenine nucleotide and caffeine, however, they showed the following quantitative differences. First, rabbit RyR showed higher Ca2+ affinity than the frog. Second, rabbit RyR showed higher activity in the presence of Ca2+ alone with less stimulation by adenine nucleotide than the frog. Third, rabbit RyR displayed less enhancement of [3H]ryanodine binding by caffeine in spite of having a similar magnitude of Ca2+ sensitization than the frog, which may explain the occasional difficulty by researchers to demonstrate caffeine contracture with mammalian skeletal muscles. Finally, but not least, rabbit RyR still showed marked inhibition of [3H]ryanodine binding in the presence of high Ca2+ concentrations in the 1 M NaCl medium, while frog RyR showed disinhibition. Other matters relevant to Ca2+ release were also discussed.

Animals↗
PubMed1999

Compensated endocytosis of LDL by hamster cells co-expressing the two distinct mutant LDL receptors defective in endocytosis and ligand binding.

The low density lipoprotein receptor (LDLR) regulates the plasma cholesterol level by mediating endocytosis of LDL. We established stable hamster cell lines expressing two LDLRs with distinct functional defects, i.e., endocytosis and ligand binding. In the cell line expressing only I189D h/r (human-rat chimeric) LDLR, defective in LDL binding, very little amount of LDL was internalized, although the receptor was endocytosed efficiently. In the cell line expressing Y807C LDLR solely, very few receptors were located in coated pits or endocytosed, while LDL binding to the receptor was not disrupted. In striking contrast, in the cells co-expressing both receptors, a much larger number of Y807C LDLR were internalized and co-located with I189D h/r LDLR in the perinuclear region. In these cells, LDL was bound exclusively to Y807C LDLR and its uptake was enhanced by 80% as compared to the cell expressing Y807C LDLR solely, whereas LDL binding affinity was not changed. These results suggest that a defect of the essential motif for endocytosis, cysteine 807, could be compensated by co-expression of I189D h/r LDLR, but the LDL binding was not affected.

Animals↗
PubMed1999

[Problems with employment of a staff anesthesiologist in a local hospital].

Yukiguni Yamato General Hospital (199 beds) is one of main local hospitals of Minamiuonuma area in Niigata prefecture. From June 1997, an anesthesiologist has been employed as a staff of this hospital instead of parttimers. We examined whether employment of an anesthetic staff was useful for a local hospital or not, in terms of clinical and cost advantages. There were benefits in explaining the nature of anesthesia, possible risks, operating room and pre-postoperative procedures to the patients. And there were advantages in reducing anesthetic management fee, in shortening the staying time in operating room. We conclude that there are many benefits in obtaining an anesthesiologist for a local hospital staff, but there are some drawbacks in having to work alone.

Anesthesiology↗