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Biomedical subjects

N Imai

Publications and source records attributed to N Imai.

At least 199 records · Page 11Linked to original sources
PubMed1981

The release of monovalent counterions by addition of divalent countemons to aqueous solutions of maleic acid copolymer.

Divalent cation binding and the release of monovalent cations accompanying the cation binding were experimentally studied by ion-selective electrode methods in aqueous solutions of copolymer of maleic acid and ethyl vinyl ether. It was found that in the process of Ca2+ addition, all the Ca2+ added was bound to polyions and the initially condensed Na+ was released in proportion to the concentration of the added Ca2+ up to the critical concentration of added Ca2+ at which the condensation of Ca2+ ceases. Values of the structural charge density parameter xi(s), were determined from the end-points of condensation of Ca2+. The process of Na+ release by adding Ca2+ was analyzed on the basis of the counterion condensation theory by using these xi(s) values. In addition, the relationship between the activity coefficient gamma-- of Ca2+ and degree of neutralization alpha in salt-free solutions was obtained from the Manning theory. Agreement between the calculated and experimental values was excellent in both cases.

Journal Article↗
PubMed1981

Regional changes in cardiac structural proteins in myocardial infarction: biochemical and histologic correlates.

1. Quantitative analysis of structural proteins from a minute amount of myocardial tissue was performed from 10 mu thick cardiac tissue slices weighing 2 to 5 mg by the extraction in glycerol solution and by sodium dodecylsulfate (SDS) gel electrophoresis, and these changes were compared with the histologic alterations in the striated structure of the adjacent cardiac slices in the experimental myocardial infarction in the dog. 2. Approximately 69 micrograms of structural proteins were obtained from 1 mg of the normal heart muscle. In the central portions of the myocardial infarction, reductions in myosin heavy chain (HC), light chain (LC) 1 and alpha-actinin were observed at 12 to 24 hours after the coronary occlusion followed by the decrease in myosin LC 2 at 48 hours. Those changes became intense at 72 hours to 7 days, but restored gradually at 14 to 28 days. 3. Alterations in the striated structure of cardiac muscle fibers of the adjacent tissues slices were found simultaneously with the changes in structural proteins. At 12 to 24 hours after the coronary ligation increase in eosinophilia and overstretch of cross-striation were observed. The findings of coagulation necrosis, loss of striation, fragmentation, swelling of A-band, etc. of the infarcted fibers were markedly observed at 48 hours to 7 days, but the histologic restoration of cardiac fibers was found with the recovery of the infarcted tissue at 14 to 28 days after the coronary ligation. 4. Changes in the compositions of structural proteins corresponded well to the alterations in the striated structure in chronology and in quantity.

Actinin↗
PubMed1981

Studies on the preventive method of lowered ventricular fibrillation threshold during experimental acute myocardial infarctions. A comparison between disopyramide phosphate and lidocaine.

This study was performed to investigate the prophylactic effect of disopyramide phosphate on ventricular fibrillation in acute myocardial infarction. Lidocaine and disopyramide phosphate were compared in terms of their effects on the lowered ventricular fibrillation threshold in experimental myocardial infarction produced by coronary ligation in dogs. The following results were obtained: 1) The effect of lidocaine i.v. + infusion appeared promptly and the ventricular fibrillation threshold exceeded control levels from 45 min onwards (p less than 0.01). 2) The i.m. injection of lidocaine was effective in a dose of 10 mg/Kg. The minimally effective blood level was 1.7 mcg/ml. 3) Disopyramide phosphate 5 mg/Kg i.v. produced a tendency towards recovery from 15 min onwards. After 30 min, the ventricular fibrillation threshold was significantly higher than control (p less than 0.01). 4) Disopyramide phosphate 5 mg/Kg i.m. was initially effective after 45 min. The effect was significant from 1 hour and 30 min onwards, compared with control (p less than 0.01). The minimally effective blood level was 2.4 mcg/ml. 5) Disopyramide phosphate 2 mg/Kg i.m. produced a tendency towards recovery but the difference from the control was not significant. 6) In equivalent i.m. doses, disopyramide phosphate tended to be more potent than lidocaine in increasing the ventricular fibrillation threshold. 7) In the aforementioned doses, disopyramide phosphate did not cause any marked changes in PQ interval or QT time in ECG. These results suggest that the intramuscular injection of disopyramide phosphate is a hopeful clinical treatment to prevent ventricular fibrillation in the very early stages of acute myocardial infarction.

Animals↗
PubMed1980

An electrochemical study of the iron storage protein, ferritin.

The electrochemical behavior of iron storage protein, ferritin (molecular weight 700 000) was studied by pulse polarography, cyclic voltammetry and 'potentiometry' monitored by colorimetry. Comparison between in vivo and voltammetric redox reactions of the ferritin Fe(III) core and thermodynamic E'0 values for native ferritin are described.

Electrochemistry↗
PubMed1980

Estimation of bound quaternary ammoniumion to a rod-like polyion with a large alkyl residue.

The amount of quaternary ammonium ion (Bu4N+), which is believed not to be bound to general carboxylpolyelectrolytes, bound to poly(iso BVE-co-MA) was estimated by conductivity measurements. In the region of the density of polyion charge in which the polyions are thought to take a free drain'ng conformation, it has been confirmed that the activity coefficient of Bu4N+ ions is less than 0.5 in the presence of a small amount of Bu4NCl, showing that the force between the counterions and the polyion is probably due to the hydrophobic interaction. Moreover, from the electrophoretic mobility Up of the polyion observed from the data of conductivity, it has been ascertained that Up of this polyion is two times larger than PAA, and the behavior of the quantity e/xiP with changing degree of ionization corresponds to that of the viscosity.

Journal Article↗
PubMed1980

The release of monovalent counterions by addition of divalent counterions in coulombic interaction system.

The additivity rule of counterion activity or osmotic pressure in rodlike polyelectrolyte solutions has been discussed on the basis of the Fokker-Planck and Poisson equations in relation to the fluctuation of counterion distribution. This new theory has concluded that the additivity rule of counterion activity is less applicable than that of osmotic pressure due to the electric expansion force acting on the free-volume surface resulting from the fluctuation of counterion distribution. The theory has introduced an approximate relation between the counterion activities in the mixture solution of divalent and monovalent counterions, such that Deltaa+ = DeltaC++ - Deltaa++, in which Deltaa+ represents the increase of activity of monovalent counter-ions resulting from the addition of divalent counterionsDeltaC++, (in molar) to the solution, and Deltaa++ means the increase of the divalent counterion activity (in molar) in this process. This relation has been experimentally examined for Na-PSS solutions in the process of Cu2+ ion addition by the use of Na+ and Cu2+ sensitive electrodes, and it has been turned out that the relation is established in the low charge state of polyion.

Journal Article↗
PubMed1980

Dielectric increment in polyion solutions due to the distortion of counterion distribution.

A theory of DC dielectric increment, delta, has been constructed based on the Fokker- Planck and Poisson equations on the mechanism of the distortion of spatial counterion distribution around a rodlike polyion under the applied electric field, E, perpendicular to the polyion lod. The DC dielectric constant of polyion solutions can be obtained analytically in the both cases of absence and presence of counterion-flow. The nonlinearity of the Poisson-Boltzmann equation in the absence of E has given the interesting behaviors of delta. The calculation in the absence of counterion-flow has shown the delta-values having the same order of magnitude as the experimental data at the higher frequency range (around 100 kHz), and the importance of this mechanism has been pointed out.

Journal Article↗
PubMed1977

Immunofluorescent studies of urinary casts.

Immunofluorescent staining of urinary casts of patients with chronic glomerulonephritis or with acute renal failure was performed. Urinary and cast Tamm-Horsfall mucoproteins were purified by a modified McQueen's method. Rabbits were immunized by both of these materials to obtain antisera. The antigenic specificity of the prepared material was examined by Ouchterlony gel diffusion method and immunoelectrophoresis. Indirect and direct immunofluorescent staining methods were done using Tamm-Horsfall mucoprotein antiserum and FITC-GARG, FITC-labelled IgG, IgA, IgM, C3 and albumin. Hyaline casts of both chronic glomerulonephritis and acute renal failure demonstrated fluorescence with Tamm-Horsfall mucoprotein antiserum. The nature of the granular casts of chronic glomerulonephritis seemed to be different from those of acute renal failure because the granules of the former fluoresced for some serum protein fractions, but the latter fluoresced only for Tamm-Horsfall mucoprotein. The absence of fluorescence with epithelial casts for any serum protein fractions implied a different pathogenesis for epithelial casts as compared to granular casts, contrary to Lippman's assumption. A routine technique of immunofluorescent staining of urinary casts was developed. The interpretation of urinary casts should be more specific by this new technique.

Acute Kidney Injury↗