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Biomedical subjects

H Miyano

Publications and source records attributed to H Miyano.

At least 19 recordsLinked to original sources
PubMed1992

Involvement of nitric oxide pathway in the PAF-induced relaxation of rat thoracic aorta.

1. The mechanism of the vasorelaxant effect of platelet activating factor (PAF) on rat thoracic aorta and the effect of aging on the PAF-induced relaxation were investigated. 2. PAF at concentrations causing relaxation induced marked increases in guanosine 3':5'-cyclic monophosphate (cyclic GMP) production, but did not induce an increase in adenosine 3':5'-cyclic monophosphate (cyclic AMP). 3. Removal of the endothelium by mechanical rubbing, and treatment with the PAF antagonists CV-3988, CV-6209 and FR-900452, the nitric oxide biosynthesis inhibitor, NG-nitro L-arginine, the radical scavenger, haemoglobin, and the soluble guanylate cyclase inhibitor, methylene blue, inhibited PAF-induced relaxation and abolished or attenuated PAF-stimulated cyclic GMP production. 4. The relaxation was greatest in arteries from rats aged 4 weeks. With an increase in age, the response of the arteries to PAF was attenuated. 5. Endothelium-dependent cyclic GMP production also decreased with increase in age of the rats. 6. These results suggest that PAF stimulates production of nitric oxide from L-arginine by acting on the PAF receptors in the endothelium, which in turn stimulates soluble guanylate cyclase in the smooth muscle cells, and so increases production of cyclic GMP, thus relaxing the arteries. Age-associated decrease in PAF-induced relaxation may result from a reduction of cyclic GMP formation.

Aging↗
PubMed1991

Effects of injection site on the accuracy of thermal washout right ventricular ejection fraction measurements in clinical and model investigations.

The purpose of this investigation was to improve the accuracy of measurement of thermal right ventricular ejection fraction (RVEF) using the modified Swan-Ganz catheter. Three serial ejection fractions (EFs) (EF1, 2, 3) and the mean were calculated, based on Holt's theory. RVEFs were compared between right ventricular (RV) and atrial (RA) injection in ten intensive care unit (ICU) patients using a modified catheter having RV and RA orifices (15 cm and 30 cm from the distal end, respectively), and paired duplicate (two patients) or triplicate (eight patients) measurements were performed. To determine what factors interfere with RVEF, a model heart (with diastolic volume of 150 ml) was constructed, in which model injection of cold water to the direct inflow tract (RA), to the direct mixing chamber (RV), or through the catheter running in the inflow tract were compared. When EFs were compared between RV and RA injection, those for the former were greater (RV vs RA in EF1 and EFmean: 0.46 +/- 0.15 vs 0.23 +/- 0.11 in EF1, and 0.45 +/- 0.13 vs 0.28 +/- 0.11 in EFmean, mean +/- SD, p less than 0.01). When the serial EFs were compared in each injection type, in the RV injection EF3 was the smallest as was EF1 in the RA injection. The same phenomenon was observed in the model as in the patients, and moreover when cold water was injected in RA through a catheter running through the circuit, EFs were greatly underestimated (EF1 = 0.29 +/- 0.02 at preset EF = 0.4). We conclude that these phenomena were caused by sluggish movement of the cold indicator from RA to RV when injected into RA, and by interference with the cooled cardiac chamber and catheter. Consequently, the first or second EFs obtained from RV injection might be closest to the actual values because of the least interference with those factors.

Adult↗
PubMed1991

[ARDS-like reactive respiratory failure after radical operation for esophageal cancer--with reference to PMN elastase and anaphylatoxin].

In a study undertaken to elucidate the pathophysiology underlying reactive respiratory failure following surgery for esophageal cancer, postoperative esophageal cancer patients were divided into 2 groups, i.e. one with respiratory failure (defined as impairment of oxygenating capacity with a respiratory index (RI) value of 1.5 or above, lasting from more than 5 days after surgery) and the other without it, and between-group comparisons were made of respiratory & circulatory dynamics and biologic response system components, e.g., complement, anaphylatoxins and polymorphonuclear granulocytes (PMN) elastase. There were no differences between the two groups in patient's age at operation and pulmonary function test. The mean duration of endotracheal control was 5.1 days for the respiratory failure (+) group against 3.7 days for the respiratory failure (-) group. Assessments of respiratory & circulatory dynamics showed that the RI was significantly increase early in the postoperative course in the respiratory failure (+) group as compared with the respiratory failure (-) group, while the hydrostatic pressure of pulmonary circulation (pulmonary microvascular pressure (Pmv)-plasma colloid-osmotic pressure (COP] and pulmonary shunting rate (Qs/Qt) were also elevated in the former group. Among biologic response parameters, the leukocyte count, platelet count, CH5, C3, and C5 showed long-sustained decreases from the postoperative day 1 on in the repertory failure (+) group as compared to the respiratory failure (-) while PMN elastase activity and anaphylatoxin C3a were elevated from the postoperative day 1 on in the former group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Exacerbation of hypercapnia and acidosis of central venous blood and tissue following administration of sodium bicarbonate during cardiopulmonary resuscitation.

Administration of sodium bicarbonate during cardiopulmonary resuscitation (CPR) is controversial, and our aim was to elucidate whether or not its administration is beneficial by analyzing the acid-base status and the level of carbon dioxide in central venous blood during CPR, and their changes following administration of sodium bicarbonate. Six patients were studied. They had all been admitted to the intensive care unit (ICU), had already had pulmonary arterial or central venous catheters inserted, and had acute episodes of circulatory collapse during their stay in the ICU. The following phenomena were observed: 1) hypercapnia and acidosis of central venous blood were prominent during both cardiogenic shock and CPR, although arterial hypocapnia was maintained by hyperventilation; 2) administration of sodium bicarbonate during cardiogenic shock and CPR induced exacerbation of hypercapnia and acidosis of central venous blood; 3) when arterial hypercapnia was present due to disturbed ventilation, administration of sodium bicarbonate exacerbated hypercapnia and acidosis of both arterial and central venous blood; 4) administration of sodium bicarbonate did not induce hypercapnia of central venous blood in a septic shock patient in whom the septic hyperdynamic state was prevalent in spite of low systemic perfusion pressure. It was concluded that hypercapnia and acidosis of the central venous blood and tissues were exacerbated by administration of sodium bicarbonate during CPR, and that such an effect might be dependent on the severity of the decrease in tissue perfusion.

Acid-Base Equilibrium↗
PubMed1987

Micro-scale sequence analysis from the N-terminus of peptides using the fluorogenic Edman reagent 4-N,N-dimethylamino-1-naphthyl isothiocyanate.

The fluorogenic Edman reagent 4-N,N-dimethylamino-1-naphthyl isothiocyanate (DNTC) was reacted with amino acids and peptides, cyclized by acid and the liberated 4-N,N-dimethylamino-1-naphthyl thiohydantoin (DNTH) amino acids were then separated and detected by HPLC. The fluorescence intensities of DNTH-amino acids except DNTH-proline and -serine were dramatically increased in the alkaline solution and organic solvent. Thus, the postcolumn reaction with alkaline acetonitrile solution was adopted in HPLC. The polar and aromatic amino acids afforded two DNTH-amino acids on derivatization with DNTC and cyclization with acids. These were suggested to be stereoisomers of DNTH-amino acids. The sequence analysis of 0.5 nmol Leu-enkephalin was achieved by the double coupling method with DNTC and phenyl isothiocyanate followed by the proposed HPLC system.

1-Naphthylisothiocyanate↗
PubMed1986

Amino acid composition analysis of minute amounts of cysteine-containing proteins using 4-(aminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole and 4-fluoro-7-nitro-2,1,3-benzoxadiazole in combination with HPLC.

The simultaneous determination of amino acid composition including cysteine of egg albumin, a model protein containing a/s cysteine residue, is reported. All the thiol groups of the cysteine residue(s) of egg albumin were labelled with 4-(aminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole, a fluorogenic reagent for thiol groups. The labeled egg albumin was hydrolyzed in 6N HCl at 110 degrees C for 24 h. The hydrolysate was lyophilized, derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole, a fluorogenic reagent for amines, and subjected to HPLC. 18 derivatized amino acids including double labelled cysteine were separated within 90 min on a Nucleosil ODS column (150 mm X 4.6 mm i.d.; 5 microns), and detected at 530 nm (ex. 470 nm) in a range from 90 fmol (aspartic acid) to 1.3 pmol (cysteine) (S/N = 3). Composition ratios of amino acids of egg albumin were similar to theoretical values except for methionine, which would be destroyed under the present acid hydrolysis condition. Analytical methods for cysteine residues are reviewed, and the availability of fluorogenic reagents having the benzofurazan structure is also discussed.

4-Chloro-7-nitrobenzofurazan↗
PubMed1985

Influences of metal ions on the reaction of amino and imino acids with fluorogenic reagents.

When a twofold excess of metal ions (Cu2+, Ni2+, Zn2+, Mg2+, Ca2+, Fe3+, and Al3+) was added to a reaction medium of amino acids (1-50 microM each) with the fluorogenic reagents NBD-F (4-fluoro-7-nitrobenzo-2-oxa-1,3-diazole), DNS-Cl (5-N,N-dimethylaminonaphthalenesulfonyl chloride), OPA (o-phthalaldehyde), and fluorescamine (4-phenylspiro[furan-2(3H),1'-phthalan]-3,3'-dione), a reduction of derivatization was observed. The effect was especially marked on the reaction with NBD-F. The derivatization of His and Asp with DNS-Cl and fluorescamine and of His with OPA was suppressed by Cu2+ and/or Ni2+. The suppression by the metal ions can be overcome by the addition of EDTA to the reaction medium. For determination of a small amount of amino and imino acids (less than microM) the addition of a chelating reagent to biological samples is recommended before derivatization with these electrophilic reagents.

4-Chloro-7-nitrobenzofurazan↗
PubMed1985

A surface electrode array for detecting action potential trains of single motor units.

Action potentials of single motor units were detected by a linear surface electrode array placed perpendicular to the longitudinal axis of the biceps brachii. Twelve myoelectric signals were derived simultaneously from a voluntarily contracting muscle. Using a visual feedback control, 3 subjects produced spike trains of single motor unit action potentials (MUAPs) at a weak contraction. When the myoelectric signals showed an interference pattern at a moderate contraction, several MUAPs were isolated by a visual analysis. MUAPs occurring at about fixed intervals with constant amplitudes and with identical wave forms were presumed to be the action potential trains of single motor units. Reliable estimates of single MUAP wave forms were obtained by averaging and superimposing the detected signals at a timing of characteristic potential peaks. Then not only the firing rate of the spikes but also the territory and the wave form of single MUAPs were investigated. Most MUAPs had a sharp and symmetrical distribution of potentials on a skin surface along the muscle circumference, while some MUAPs showed complex wave forms with some separate potential peaks. The possible arrangement of muscle fibers belonging to the motor units was estimated from the MUAP wave forms.

Action Potentials↗
PubMed1979

Theoretical analysis of surface EMG in voluntary isometric contraction.

A new stochastic model of the surface EMG is suggested and the spectral density of the surface EMG is studied theoretically and experimentally to confirm the validity of this model. Theoretical results show that while the contraction level is not so high, the shape of the spectral density (distribution) does not change and its amplitude is directly proportional to the motor unit firing frequency and recruitment. To illustrate the theoretical results, experiments were carried out for rectus femoris and biceps brachii. The surface EMG was lead off by bipolar surface electrodes. And the spectral density of the surface EMG was calculated using FFT algorithm. From these experimental results, it was confirmed that our theoretical results were almost valid.

Electromyography↗
PubMed1976

Specific action of 4-nitropyridine 1-oxide on Excherichia coli K-12 pro+ strains leading to the isolation of proline-requiring mutants: isolation and characterization of pro-mutants.

A specific action of 4-nitropyridine 1-oxide on Escherichia coli K-12 Pro(+) strains leading to highly efficient, selective isolation of Pro(-) mutants is described. Incubation of Pro(+) cells with a sublethal concentration of 4-nitropyridine 1-oxide in Penassay broth gave Pro(-) mutants, which lacked either the biosynthetic pathway of proline from glutamic acid to glutamyl gamma-phosphate (proB(-)) or the pathway from glutamyl gamma-phosphate to glutamic gamma-semialdehyde (proA(-)) or both. Pro(-) mutants, which have the metabolic block between Delta(1) pyrroline-5-carboxylate (the cyclized dehydration product of glutamic gamma-semialdehyde) and proline (proC(-)) were not found among survivors. Treatment of Pro(+) cells with N-methyl-N'-nitro-N-nitrosoguanidine led to isolation of all three types of Pro(-) mutants, suggesting that the action of 4-nitropyridine 1-oxide on Pro(+) cells is apparently distinct from the action of N-methyl-N'-nitro-N-nitrosoguanidine. F-duction and interrupted mating experiments led to determination of the correlation between proline loci and the biosynthetic pathway of proline from glutamic acid.

Culture Media↗
PubMed1976

Specific action of 4-nitropyridine 1-oxide on Escherichia coli K-12 Pro+ strains leading to the isolation of proline-requiring mutants: mechanism of action of 4-nitropyridine 1-oxide.

Possible mechanisms involved in the action of 4-nitropyridine 1-oxide (4NPO) on Escherichia coli K-12 pro(+) cells in Penassay broth leading to the selective isolation of proA(-) and/or proB(-) mutants but not proC(-) mutant were studied. Reconstruction experiments between pro(+) and pro(-) cells, together with experiments on the bactericidal action of 4NPO on pro(+) and pro(-) cells, indicated that 4NPO is more toxic for pro(+) and proC(-) cells than for proA(-) and proB(-) cells. These results, coupled with data indicating little mutagenicity of 4NPO on E. coli cells, led us to conclude that the selection of proA(-) and/or proB(-) cells that arose spontaneously in the pro(+) culture is a possible mechanism for the action of 4NPO. Examination of 4NPO sensitivity of pro(+) transductants derived from proA(-) and proB(-) cells with P1 vir phage and pro(+) cells as donor and of pro(+) spontaneous revertants derived from those pro(-) cells suggested that 4NPO-sensitive gene(s) should be on, or very close to, the proA and proB loci and that both products of proA and proB genes may be involved in the sensitivity of bacteria to 4NPO. The fact that the 4NPO-sensitive allele is dominant over the 4NPO-resistant allele further indicated the possible correlation between gene products of proA and proB and the 4NPO sensitivity of bacteria. Experiments on metabolic conversion of 4NPO with bacterial cells proved that the major metabolic pathway of the agent is reduction to (possibly via 4-nitroso-) 4-hydroxylamino- and 4-amino-pyridine 1-oxides, and then to 4-aminopyridine. Investigation of the effect of structural modification of 4NPO on the elective selection of Pro(-) mutants in Pro(+) culture further suggested that the structural feature indispensable for the action of the agent is the hydroxyl-amino or its more oxidized state at the 4 position and the N-oxide moiety at the 1 position on the pyridine skeleton. Action of 4NPO in minimal medium was found to be bacteriostatic on pro(+) cells but not on pro(-) cells, leading to the formation of long nonseptate multinucleate filament cells on pro(+) cells. Possible biochemical mechanisms of the selective toxicity of 4NPO for pro(+) and pro(-) cells are discussed.

Escherichia coli↗