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Biomedical subjects

N Ikeda

Publications and source records attributed to N Ikeda.

At least 343 records · Page 19Linked to original sources
PubMed1985

Affinity chromatography of human serum proteins using immobilized lectin from Allomyrina dichotoma.

The beta-D-galactoside-specific lectin from Allomyrina dichotoma reacts with serum proteins which contain the corresponding carbohydrate moieties. By affinity chromatography of human serum using the insolubilized lectin coupled to Sepharose, it is possible to fractionate human serum proteins in 2 groups: those which react with the lectin (alpha 1-acid glycoprotein, haptoglobin, etc.) and those which do not (albumin, Gc-globulin, etc.). IgG is the only serum protein that can be found in both groups.

Blood Proteins↗
PubMed1984

Effects of flecainide on ventricular function: clinical and experimental correlations.

Flecainide has unusual electrophysiologic properties and a high potency for the suppression of ventricular tachyarrhythmias. Little is known about its inotropic and hemodynamic actions. In isolated rabbit papillary muscle, it produced a concentration-dependent depression of contractile force, the threshold concentration being 1.0 micrograms/ml. In patients undergoing coronary angiography for ischemic heart disease and given 1 (n = 11) and 2 mg/kg (n = 11) of flecainide acetate i.v., there was no change in heart rate or mean arterial pressure. The vehicle in which i.v. flecainide was suspended had no significant effects in 6 patients in whom it was tested. Both doses produced comparable hemodynamic effects irrespective of the level of the left ventricular ejection fraction. The mean right atrial pressure increased by 12% (p less than 0.05) after 1 mg/kg and by 15% (p less than 0.01) after 2 mg/kg of the drug. The corresponding increases in mean wedge pressure were 44% (p less than 0.05) and 33% (p less than 0.05), in mean pulmonary artery pressure 27% (p less than 0.01) and 28% (p less than 0.05), in systemic vascular resistance 10% (p less than 0.05) and 9% (not significant [NS]) and in pulmonary vascular resistance 6% (NS) and 49% (p less than 0.05). Significant decreases in cardiac index (8 and 12%, p less than 0.05), stroke volume index (11 and 15%, p less than 0.01) and stroke work index (12%, p less than 0.05, and 21%, p less than 0.01) as well as in left ventricular ejection fraction (15 and 16%, p less than 0.01) were also induced by the 2 doses of flecainide.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Serum and myocardial kinetics of amiodarone and its deethyl metabolite after intravenous administration in rabbits.

The serum kinetics of amiodarone and its major metabolite the deethyl analogue were studied in rabbits after intravenous administration. The elimination of the drug and the metabolite from serum occurred as a biexponential function. Both compounds exhibited a rapid distribution phase (6.5 and 4.4 min, respectively) and had elimination half-lives of 136 and 235 min, respectively. There was a rapid uptake of both drugs by the myocardium, with maximal concentrations at 5 and 15 min. The myocardial concentrations were higher than the respective serum concentrations and declined with time. There was a wide scatter in myocardium-serum ratios, which ranged from 1 to 11 for amiodarone and 12 to 29 for the metabolite. Neither the drug nor the metabolite produced significant changes in the surface electrocardiogram after intravenous administration. These data suggest that accumulation of the metabolite does not account for the slow onset of action of amiodarone.

Amiodarone↗
PubMed1984

A new alpha 2HS-glycoprotein typing by isoelectric focusing.

Isoelectric focusing (pH 4.0-5.0) of serum alpha 2HS-glycoprotein on polyacrylamide gels has been found to be a useful tool in population genetics and forensic science. Using this method, we isolated three common types, alpha 2HS 1-1, alpha 2HS 2-1 and alpha 2HS 2-2, and showed that alpha 2HS types are determined by two autosomal codominant alleles, alpha 2HS1 and alpha 2HS2. The method is simple, fast and easy to perform. Results of typing for the two alleles, alpha 2HS1 and alpha 2HS2, are described for a Japanese population sample (n = 1003).

Alleles↗
PubMed1984

A new alpha 2HS-glycoprotein allele (AHS*5) in two Japanese families.

Serum specimens of two unrelated Japanese males had a new variant of the alpha 2HS-glycoprotein phenotypes. They had unusual bands designated AHS 5. Family studies indicated that the new variant phenotypes were determined by a new allele, AHS*5, in combination with a common allele AHS*1 or AHS*2, and that the new allele had an autosomal codominant inheritance with other AHS alleles. The frequency of the new alpha 2HS-glycoprotein allele, AHS*5, is 0.0005.

Alleles↗
PubMed1984

Electrophysiologic effects of amiodarone: experimental and clinical observation relative to serum and tissue drug concentrations.

Oral amiodarone is a potent antiarrhythmic agent with a slow onset of action. Its electrophysiologic properties following chronic administration are well known, but its acute electrophysiologic actions are poorly defined. The objectives of the present study were to correlate the electrophysiologic actions of intravenous amiodarone in humans with the acute and chronic effects of the drug relative to plasma and tissue concentrations of the drug. In humans (n = 10), 5 mg/kg intravenous amiodarone (serum concentration 6.50 +/- 3.34 micrograms/ml at 10 minutes; 2.13 +/- 0.71 micrograms/ml at 20 minutes, n = 7) increased the AH interval by 16.4% (p less than 0.005), the antegrade effective refractory period (ERP) of the atrioventricular (AV) node by 14.4% (p less than 0.025), and the functional refractory period (FRP) of the AV node by 15.5% (p less than 0.005). The ERP or FRP of the atrium of the right ventricle was not significantly changed; there was no effect on the HV interval or the QT and R-R intervals of the ECG. In rabbits (n = 11) given 10 mg/kg intravenous amiodarone (mean +/- SD serum concentration 0.49 +/- 0.17 micrograms/ml; mean myocardial concentration 7.0 +/- 1.9 micrograms/gm, n = 3), there were no significant effects on the ECG intervals. In isolated rabbit sinoatrial (SA) node, atria, and AV node (three preparations) superfused with 5 X 10(-6)M amiodarone (3.41 micrograms/ml), there was no effect on the action potential duration (APD) or other parameters of the transmembrane potential.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1984

Decreased serum levels of a factor stimulating prostacyclin synthesis in acute myocardial infarction.

To investigate the role of a factor in serum stimulating prostacyclin synthesis in acute myocardial infarction, we compared the activities of the factor among 7 patients with acute myocardial infarction (2.5 +/- 0.8 hrs and 80 +/- 17 hrs after the onset of symptoms), 12 patients with angina pectoris, and 7 normal subjects. In this study, we found that in patients with acute myocardial infarction, this activity is much lower immediately after infarction (2.5 +/- 0.8 hrs) than 80 +/- 17 hrs later, or in patients with stable angina pectoris, or in healthy volunteers. Since prostacyclin is antiaggregating and vasodilating, the deficiency in this ability during the very early phase of acute myocardial infarction may be related to the development of the thrombosis of acute myocardial infarction.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

The clinical results of amiodarone in cardiac arrhythmias: optimal dosing.

Amiodarone hydrochloride is a relatively new antiarrhythmic agent, the properties of which differ in a significant manner electrophysiologically, pharmacokinetically and structurally from those of conventional as well as other investigational antidysrhythmic compounds. It is also pharmacologically unique in so far as its fundamental action on cardiac muscle following chronic therapy differs markedly from that found during the intravenous administration; its I.V. action is dominated by the lengthening of intranodal (AV) conduction time and the effective refractory period of the AV node, the electrophysiologic basis for which is unclear but accounts for the slowing of the ventricular response in atrial flutter and fibrillation and the variable conversion rate of narrow QRS reentrant paroxysmal supraventricular tachycardia. Intravenous amiodarone is ineffective in most other arrhythmias; it does not lengthen repolarization, nor does it prolong the effective refractory period of atria, ventricle, His-Purkinje system or the accessory pathways of the heart in the WPW syndrome. In contrast, chronically administered amiodarone lengthens repolarization and the effective refractory period of all cardiac tissues as a function of dose and duration of therapy consistent with its wide spectrum of antiarrhythmic activity in the prophylactic control of supraventricular and ventricular tachyarrhythmias. The nature of the slow onset of action of the oral drug is not well-understood; it may be due to the slow formation of active metabolites or the gradual and selective inhibition of T3 action on the myocardium since the effects of amiodarone on cardiac repolarization are identical to those of hypothyroidism and are negated by the concomitant administration of thyroxine. Serum reverse T3 levels increase as a function of dose and duration of amiodarone therapy and tentative data indicate that serial measurements of rT3 levels may provide a reliable index for gauging efficacy and toxicity of amiodarone during chronic therapy. The role of serum drug and metabolite levels appears less reliable in this regard. The exceedingly long and variable elimination half-life of amiodarone necessitates individualized loading and maintenance dosage regimens, and the latency of onset of antiarrhythmic action during oral therapy is not shortened by intravenous bolus injections or sustained infusions. However, the judicious choice of oral dosage as discussed herein permits the development of an effective prophylactic regimen for most patients with supraventricular and ventricular tachyarrhythmias; when the lowest dosage regimen to control a particular arrhythmia is identified, limiting side

Amiodarone↗