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Y Miyamoto

Publications and source records attributed to Y Miyamoto.

At least 325 records · Page 18Linked to original sources
PubMed1995

The dopaminergic system modulates the endogenous opioid system in guinea-pig isolated ileal longitudinal muscle.

The effects of the dopamine antagonists haloperidol and sultopride were investigated on the twitch response, evoked by 0.1 Hz stimulation of guinea-pig isolated ileal longitudinal muscle, and on the inhibition of the twitch response induced by 10 Hz stimulation (post-tetanic twitch inhibition) and by application of opioids. Both haloperidol and sultopride concentration-dependently inhibited the twitch response, with threshold concentrations of 2 and 50 microM, respectively, and could also shift the concentration-response curve for ACh-contraction to the right in a non-competitive manner. Haloperidol (1 microM) and sultopride (20 microM) increased post-tetanic twitch inhibition and this could be prevented by naloxone (100 nM). Twitch inhibition induced by morphine and dynorphin 1-13 was not affected by haloperidol (1 microM) or sultopride (20 microM). Prazosin (1 microM) and yohimbine (2 microM) did not affect either the twitch response or the post-tetanic twitch inhibition. These results suggest that dopamine receptors are involved in the modulation of the ileal opioid system, in such a manner as to diminish the release of endogenous opioids by tetanic stimulation.

Amisulpride↗
PubMed1995

Non-decay type fast-setting calcium phosphate cement: composite with sodium alginate.

Non-decay type fast-setting calcium phosphate cement (nd-FSCPC) was prepared by introducing sodium alginate (0-2.0 wt%) into the liquid phase of FSCPC. nd-FSCPC was stable even when the cement paste was immersed in distilled water immediately after mixing, whereas conventional FSCPC (c-FSCPC) decayed completely within 1 min upon immersion. The setting time of the cement, approximately 5 min, was not dependent on the presence of sodium alginate. In contrast, the introduction of sodium alginate into conventional CPC, i.e. CPC without neutral phosphate in the liquid phase, resulted in no setting when the amount of sodium alginate introduced was more than 1 wt%. Powder X-ray diffraction analysis revealed no significant difference for the conversion of cement to apatite for any concentrations of sodium alginate studied (0-2.0 wt%). The mechanical strength of the cement increased rapidly with the addition of sodium alginate up to 0.8 wt% when the cement paste was immersed and kept in distilled water at 37 degrees C, whereas further addition of sodium alginate decreased the mechanical strength. The results obtained in this investigation, taken together with sodium alginate's known excellent biocompatibility and absorption behaviour, indicate that the use of sodium alginate composite FSCPC as nd-FSCPC should be of value in orthodontics and oral and maxillofacial surgery where the cement is exposed to blood.

Alginates↗
PubMed1995

In vivo setting behaviour of fast-setting calcium phosphate cement.

The in vivo setting behaviour of fast-setting calcium phosphate cement (FSCPC) between femoral muscles of the rat was investigated to evaluate the possible value of FSCPC for medical and dental application. Conventional CPC (c-CPC) and FSCPC were implanted between femoral muscles, and various aspects of the setting behaviour such as setting time, mechanical strength and conversion ratio of cement into hydroxyapatite (HAP: Ca10(PO4)6(OH)2) were measured by the Vicat needle method, diametral tensile strength (DTS) measurement, and quantitative powder X-ray diffraction (XRD) analysis, respectively. The setting time of FSCPC in vivo was 5-7 min, in contrast to 48 min for c-CPC. As a result of its fast setting, set specimens of FSCPC showed higher mechanical strength from the initial stage than c-CPC. Higher DTS values were observed in FSCPC than c-CPC implanted after 24 h. Powder XRD analysis revealed faster conversion of FSCPC than c-CPC into HAP, which was responsible both for the faster setting and higher mechanical strength from the initial stage. We concluded, therefore, that FSCPC may be used for a wide range of clinical applications, i.e. fields where fast setting is required such as orthopaedic, plastic and reconstructive, and oral and maxillofacial surgery.

Animals↗
PubMed1995

Development of calcium phosphate based functional gradient bioceramics.

A functional gradient bioceramic that can function gradually with respect to body tissue was studied by changing the composition of calcium phosphate gradually from the surface to the inside. Diamond powder was spread on the surface of compact hydroxyapatite (HA) powder and fired at 1280 degrees C under reduced pressure, followed by firing under atmospheric conditions. The sintered body thus prepared was dense and alpha-tricalcium phosphate (alpha-TCP: alpha-Ca3(PO4)2) was found on its surface. The content of alpha-TCP gradually decreased with increasing depth from the surface. In contrast, the content of HA increased with increasing depth from the surface. The gradient ratio of alpha-TCP and HA depends on the firing time for each condition, i.e. reduced or atmospheric pressure. The alpha-TCP formation was ascribed to the decomposition of HA due to the spontaneous combustion of diamond powder.

Biocompatible Materials↗
PubMed1995

Rapid gastric emptying and pathological changes of vagus nerve in the spontaneously diabetic Chinese hamster.

To estimate autonomic neuropathy in the spontaneously diabetic Chinese hamster, which is an established strain for the non-obese non-insulin-dependent diabetes mellitus model, gastric emptying and morphometric analysis of the vagus nerve were studied in 12-month-old spontaneously diabetic Chinese hamsters (duration of diabetes was 9 months). Gastric emptying was determined by the phenol red method. Vagus was obtained from just above the diaphragm. Morphometric analysis of myelinated fibers was performed light-microscopically using semi-thin sections and unmyelinated fibers were studied electron-microscopically using ultra-thin sections. Gastric emptying of spontaneously diabetic Chinese hamster was significantly increased compared with control (86.6 +/- 1.9 vs. 51.2 +/- 3.4, P < 0.01). Myelinated fibers of the spontaneously diabetic Chinese hamster were not different from control animals, while the size of unmyelinated fibers in the spontaneously diabetic Chinese hamster was significantly decreased. These data suggest that pathological changes in unmyelinated fibers, which consist mainly of afferent fibers, might play a role in gastric motor dysfunction in the spontaneously diabetic Chinese hamster.

Animals↗
PubMed1995

Allogeneic peripheral blood stem cell transplantation for treatment of induction failure in a patient with Philadelphia chromosome-positive acute lymphoblastic leukemia.

We report a successful case of allogeneic peripheral blood stem cell transplantation (PBSCT) for the treatment of primary induction failure in acute lymphoblastic leukemia (ALL). The patient was a 46-year-old male with Ph-positive ALL and failed to achieve complete remission (CR). His HLA genotypically identical brother refused to donate bone marrow. Instead, PBSCs were collected by apheresis from the brother after administration of G-CSF at a dose of 10 micrograms/kg. For allogeneic PBSCT, the patient was conditioned with marrow ablative chemotherapy and received the PBSC harvest containing 7.8 x 10(4)/kg of CFU-GM, 1.8 x 10(6)/kg of CD34-positive cells and 2.7 x 10(8)/kg of T lymphocytes. After transplant, the neutrophil count exceeded 0.5 x 10(9)/l on day 16 and the platelet count exceeded 20 x 10(9)/l on day 22. CR was confirmed with tri-lineage engraftment in bone marrow samples on days 28 and 49; disappearance of the Ph-chromosome was documented. Sustained engraftment was also confirmed cytogenetically using a variable number of tandem repeat (VNTR) markers. Acute graft-vs.-host disease did not develop with conventional prophylaxis of methotrexate and cyclosporine. However, on day 85 the patient developed leukemia relapse and died on day 97. This clinical trial suggests that allogeneic PBSCT may be an alternative to allogeneic bone marrow transplantation in some limited situations.

Hematopoietic Stem Cell Transplantation↗
PubMed1995

Influence of molecular weight on passive tumour accumulation of a soluble macromolecular drug carrier.

The molecular weight-dependence of tumour capture of N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers (fractions of mw 22,000-778,000) was studied in vivo using subcutaneous (s.c.) Sarcoma 180 or B16F10 melanoma models. At 10 min, all fractions were already detectable in the tumour (1.5-3% of dose administered per gram) and those of molecular weight greater than the renal threshold showed progressive tumour accumulation up to 20% of dose administered per gram after 72 h in the Sarcoma 180 model. Tumour-selective uptake was confirmed for all copolymer fractions in both tumour models and in the sarcoma 180 model, the ratio (accumulation index, AI) of the AUC in tumour to AUC in skeletal muscle (a typical normal tissue) increasing from six to 12 with increasing copolymer molecular weight. The tumour/blood AI was greater (1-3) in the Sarcoma 180 model than the B16F10 melanoma model (0.4-1.0).

Acrylamides↗
PubMed1995

Regulation of vitamin D-responsive gene expression by fluorinated analogs of calcitriol in rat osteoblastic ROB-C26 cells.

We compared the activation of vitamin D-responsive genes by 24,24-difluorocalcitriol [F2-1 alpha,25(OH)2D3] and 26,26,26,27,27,27-hexafluorocalcitriol [F6-1 alpha,25(OH)2D3] with that by calcitriol [1 alpha,25(OH)2D3] in rat osteoblastic ROB-C26 cells. F2-1 alpha,25(OH)2D3 and F6-1 alpha, 25(OH)2D3 were ten times more potent than 1 alpha,25(OH)2D3 in inducing the expression of 1 alpha, 25(OH)2D3-24-hydroxylase (24-OHase) mRNA 6 h after adding vitamin D compounds. The lower affinity of these two fluorinated analogs compared with that of 1 alpha,25(OH)2D3 for vitamin D binding protein in serum (serum DBP) seemed to be partly involved in their increased ability to activate the 24-OHase gene. A time course study revealed that the expression of the 24-OHase and osteopontin mRNAs in the cells incubated with 1 alpha, 25(OH)2D3 and F2-1 alpha,25(OH)2D3 attained maximal levels at 6 h for 24-OHase mRNA and 18 h for osteopontin mRNA, the both decreased thereafter. On the contrary, F6-1 alpha,25(OH)2D3 increased the expression of 24-OHase and osteopontin exponentially until 72 h. While F2-1 alpha,25(OH)2[1 beta-3H]D3 was catabolized quickly by ROB-C26 cells, F6-1 alpha,25(OH)2[1 beta-3H]D3 was slowly and quantitatively converted into putative 26,26,26,27,27,27-hexafluoro-23S-hydroxy[1 beta-3H]calcitriol (F6-1 alpha,23S,25(OH)3[1 beta-3H]D3). This may explain why the time-course profiles of the accumulation of mRNAs for 24-OHase and osteopontin differed in the cells exposed to the fluorinated analogs. In addition to the longer retention, unknown up-regulating mechanisms appeared to be involved in the exponential activation of the 24-OHase and osteopontin genes induced by F6-1 alpha,25(OH)2D3.

Animals↗
PubMed1995

Primary structure of N-acyl-D-glutamate amidohydrolase from Alcaligenes xylosoxydans subsp. xylosoxydans A-6.

The gene coding the N-acyl-D-glutamate amidohydrolase of Alcaligenes xylosoxydans subsp. xylosoxydans A-6 (Alcaligenes A-6) was cloned and its complete DNA sequence was determined. The N-acyl-D-glutamate amidohydrolase structural gene consists of 1,464 nucleotides and encodes 488 amino acid residues. The molecular weight of the enzyme was calculated to be 51,490. This value is close to the apparent molecular weight of 59,000 determined for the purified enzyme from Alcaligenes A-6 by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE). The N-terminal amino acid sequence of the recombinant protein exactly matches the amino acid sequence derived from the DNA sequence and that determined from the Alcaligenes A-6 enzyme (NH2-MQEKLDLVIEGGWVIDGLGG). The deduced amino acid sequence of the cloned N-acyl-D-glutamate amidohydrolase showed high sequence homology with those of N-acyl-D-aspartate amidohydrolase (46%) and D-aminoacylase (47%) from Alcaligenes A-6. This fact strongly suggests that these three enzymes have evolved from a common ancestral gene.

Alcaligenes↗
PubMed1995

Safety and pharmacokinetics of iotrolan in hysterosalpingography. Retention and irritability compared with Lipiodol.

RATIONALE AND OBJECTIVES: The authors compared the safety and pharmacokinetics of Iotrolan (water-soluble) in hysterosalpingography (HSG) with those of Lipiodol (oil-soluble). METHODS: Iotrolan and Lipiodol were administered intraperitoneally at doses of 100 mg iodine/kg to female rabbits. Retention in the body was investigated by x-ray imaging, plasma kinetics, and urinary and fecal excretion. Irritability in the abdomen was investigated by histologic examination. RESULTS: Iotrolan was entirely excreted into the urine within 2 days after administration. Conversely, Lipiodol was excreted into the urine, had a half-life of 50 days, and was retained for more than 21 days in the abdomen. Iotrolan induced no inflammatory reaction in the abdomen, whereas Lipiodol induced a marked abdominal inflammatory reaction, including granuloma formation. Iotrolan had no effect on iodine concentration in the thyroid; Lipiodol increased iodine concentration significantly. CONCLUSIONS: Iotrolan, which is a water-soluble and nonionic dimeric contrast medium, has potential greater safety for use in HSG than Lipiodol.

Abdomen↗
PubMed1995

Augmented expression of the endothelin-A receptor gene in cultured mesangial cells from stroke-prone spontaneously hypertensive rats.

1. To elucidate the role of endothelin (ET) receptor in hypertension, we studied the expression of the ET-A receptor (ET-AR) gene and the ET-B receptor (ET-BR) gene in cultured mesangial cells isolated from stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto (WKY) rats. 2. The mesangial cells from both SHRSP and WKY expressed ET-AR predominantly. The level of the ET-AR mRNA in mesangial cells from SHRSP was 5-fold higher than that in the cells from WKY. The ET-BR mRNA in the mesangial cells from both strains was hardly detectable by northern blot analysis. 3. These results demonstrate that the expression of the ET-AR gene was markedly augmented in mesangial cells from SHRSP.

Animals↗
PubMed1995

Endothelin-induced activation of mitogen-activated protein kinases in glomerular mesangial cells from normotensive and stroke-prone spontaneously hypertensive rats.

1. Kinase assay in myelin basic protein (MBP) containing polyacrylamide gels revealed that endothelin-1 (ET-1) and ET-3 increased MBP kinase activities in glomerular mesangial cells (MC) from Wistar-Kyoto (WKY) rats and spontaneously hypertensive rat (SHRSP). ET-1 stimulated MBP kinase activities more potently than ET-3. 2. Immunoprecipitation with anti-41-kDa MAPK antiserum showed that the MBP kinases activated by ET-1 correspond to 43- and 41-kDa MAPK. 3. Since Phorbol 12-myristate 13-acetate, a direct activator of protein kinase C, also activated MAPK, protein kinase C was suggested to mediate ET-induced activation of MAPK. 4. These results suggest that MAPK may mediate the ET actions in glomerular mesangial cells from normotensive rats as well as spontaneously hypertensive rats. Since ET is produced by vascular endothelial cells of the kidney and glomerular mesangial cells, the ET signalling pathway may have some physiological and pathophysiological significance in vivo glomerulus.

Animals↗
PubMed1995

A model analysis of asymmetrical response of pulmonary VO2 during incremental and decremental ramp exercise.

The responses of gas exchange and ventilatory variables exhibit obvious asymmetry between the incremental and decremental phases of trapezoidal ramp exercise (29). Computer simulation was performed to explore the possible mechanisms producing this asymmetry of pulmonary O2 uptake (VO2) dynamics. The model consisted of three compartments (the lungs, the exercising muscles, and the other organs and tissues), which were perfused by respective regional circulations. Exercise was simulated by increasing the pulmonary blood flow (Q) and the muscle. VO2 in proportion to work rate. The dynamic responses of Q and the muscle VO2 were assumed to obey first-order linear kinetics. The ratio of blood flow in the muscle compartment to total cardiac output was assumed to increase linearly with work rate. Our simulation demonstrated that the muscle blood flow and mixed venous O2 content exhibited significant asymmetry between the incremental and decremental phases of exercise. The model suggested that the asymmetry of VO2 between incremental and decremental ramp exercise was dependent on the redistribution ratio of blood flow to the working muscles. The validity of the model was then evaluated by comparing the simulated results with experimental data obtained.

Computer Simulation↗
PubMed1995

Effects of activin A on deoxyribonucleic acid synthesis, iodine metabolism, and cyclic adenosine monophosphate accumulation in porcine thyroid cells.

We have recently shown the presence of activin A in human thyroid cells. To determine whether activin A affects the growth and function of the thyroid, we investigated its effects on DNA synthesis, iodine metabolism, and cAMP accumulation in cultured porcine thyroid cells. Activin A increased DNA synthesis. This effect was abolished by addition of follistatin but additively enhanced by epidermal growth factor. In contrast, activin A significantly reduced uptake and release of iodide by the thyroid and also TSH-induced cAMP accumulation but did not inhibit the cAMP accumulation induced by forskolin. These data indicate that activin A stimulates thyroid growth irrespective of cAMP accumulation and inhibits thyroid function.

Activins↗
PubMed1995

Artificial cell-spreading of permeabilized BHK cells on fibronectin-coated substratum.

We developed a cell-spreading model of permeabilized BHK cells to analyze molecular interactions in the cell-spreading machinery. BHK cells in suspension were allowed to attach onto the fibronectin-coated cover slips at 37 degrees C for 20 min. The cells were then permeabilized with 50 micrograms/ml saponin for 10 min at 4 degrees C. Approximately 50 percent of the cell models spread in response to exogenous 1 mM ATP for 90 min at 37 degrees C. Anti-actin antibody penetrated into almost all the cell models which spread ATP-dependently. These indicate that half number of the cell models permeabilized with saponin is spread by the exogenous ATP and has pores larger than an IgG molecule.

Adenosine Triphosphate↗
PubMed1995

Cloning and sequencing of a gene encoding D-aminoacylase from Alcaligenes xylosoxydans subsp. xylosoxydans A-6 and expression of the gene in Escherichia coli.

The gene encoding the D-aminoacylase of Alcaligenes xylosoxydans subsp. xylosoxydans A-6 (Alcaligenes A-6) was cloned and its complete nucleotide sequence was identified. The D-aminoacylase structural gene consists of 1452 nucleotides and encodes 484 amino acid residues. The molecular weight of D-aminoacylase was calculated to be 51,918. This value agreed well with the apparent molecular weight of 52,000 found for the purified enzyme from Alcaligenes A-6 by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE). The N-terminal amino acid sequence (NH2-SQSDSQPFDLLRAG-) predicted by the nucleotide sequence exactly matched those of the purified D-aminoacylase both from Alcaligenes A-6 and from cloned Escherichia coli (E. coli), with the exception of the removal of the N-terminal methionine processed after translation. The purified recombinant enzyme showed almost the same enzymatic properties as the native enzyme from Alcaligenes A-6. Alcaligenes A-6 D-aminoacylase showed 25-29% homology with L-aminoacylases from Bacillus stearothermophilus, porcine and humans.

Alcaligenes↗