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Biomedical subjects

Y Tsuchitani

Publications and source records attributed to Y Tsuchitani.

At least 37 records · Page 2Linked to original sources
PubMed1989

Basic study of fluoride-releasing adhesive resin for prevention of root caries: 1. Transfer of fluorine from the resin to dentin.

Release of fluoride ion from a newly-developed fluoride-releasing resin (F-resin) into phosphate buffer and incorporation of fluorine by the dentin were studied in vitro. The rate of fluoride release (amount of daily release) from a pellet of cured F-resin showed rapid decrease to 1/2 of the initial value by day 6, and then moderate decrease to 1/4 of the initial by day 30. However, the pellet continued to release fluoride at a low but constant rate for more than 520 days. In the first 30 days after F-resin was applied to the dentin surface, large amount of fluorine was concentrated within 100 mu of the subsurface dentin. With longer incubation period, the peak concentration of fluorine at the dentin surface decreased but the depth of penetration increased to about 180 mu by day 180.

Adhesives↗
PubMed1989

Basic study of fluoride-releasing adhesive resin for prevention of root caries: 2. Enhancement of acid resistance of the dentin.

The human root dentin was covered with a fluoride-releasing resin (F-resin) and incubated for various periods up to 180 days in phosphate buffer. After removal of the F-resin, resistance of the dentin to decalcification by acetic acid--sodium acetate buffer was assessed by measuring both the amount of calcium dissolved during decalcification and the knoop hardness of dentin after decalcification. The acid resistance progressively increased for 90 days when assessed by measurement of calcium dissolution and for 30 days by measurement of the knoop hardness. The percent inhibition of calcium dissolution achieved by 30 days of incubation was about 90% of the maximal inhibition obtained by incubation in concentrated sodium fluoride solution (2.4 x 10(-2) M). The enhancement of acid resistance was not induced by the resin infiltrated layer of the surface dentin but by the fluoride released from the F-resin into the dentin.

Acetates↗
PubMed1989

[Inhibition of water insoluble glucan formation by eluate from amalgams].

The effect of the eluate from amalgam on glucan synthesis was investigated in this study in order to elucidate the mechanisms by which plaque accumulation is inhibited on amalgam but not on enamel or composite. Glucosyltransferase (GTase) was prepared from a cultured supernatant of Streptococcus mutans B 13 by the ammonium sulfate precipitation method. Five commercial amalgams were tested. The eluate from amalgams was prepared by immersing the amalgam discs (10 mm dia. x2 mm thick.) into distilled water for 2 weeks. A glucan synthesizing system was compounded using GTase (50 microliters), [14C]-sucrose (100 microliters), distilled water, and the eluate (350 microliters). After 18 h incubation at 37 degrees C, the formed water insoluble glucan was collected on glass fiber filters and its radioactivity was counted. Moreover, concentrations of zinc (Zn) and copper (Cu) in the eluates were determined by atomic absorption spectrophotometry. The eluates from Dispersalloy and Fluor alloy, which eluted Zn, were the most inhibitory for glucan synthesis. Sybraloy, which released Cu to a much greater degree than the other amalgams and its eluate showed intermediate antienzymatic activity. The other amalgams, Hi-atomic M and Spherical-D, did not effect GTase at all. The results indicated that various amalgams strongly impact inhibition rates of glucan formation.

Dental Amalgam↗
PubMed1989

Effect of several resin monomers on water insoluble glucan formation by glucosyltransferase of Streptococcus sobrinus.

The cause or mechanism by which more plaque tend to accumulate on composite resins than on any other restorative materials has yet to be sufficiently explained. The purpose of this study was to investigate a possible mechanism by clarifying the effects of several monomers on the glucosyltransferase activity from Streptococcus sobrinus. The following results were obtained. In the individual resin monomers, di-, tri- and tetra-ethylene glycol dimethacrylate (2G, 3G and 4G), Bis-GMA and UDMA showed a stimulatory tendency of water insoluble glucan (WIG) formation. However, ethylene glycol dimethacrylate (IG), polyethylene glycol dimethacrylate (9G and 14G), and MMA diminished the synthesis of water soluble glucan as the concentration of monomers was increased. In addition, the eluate from experimental resin consisted of IG and Bis-GMA decreased the production of WIG when compared to that from 3G and Bis-GMA based resin. These results indicated that it was possible to develop a composite resin which inhibits plaque accumulation by using some antienzymatic monomers.

Composite Resins↗
PubMed1989

Inhibition in vitro of caries around amalgam restorations by bonding amalgam to tooth structure.

Class 5 preparations in human molars were restored with amalgam. In half of the restorations, an experimental resin liner capable of bonding amalgam to tooth structure was used. The restored teeth were incubated in a bacterial medium containing sucrose and a culture of Streptococcus mutans. Artificial carious lesions were produced around all restorations. The experimental liner inhibited penetration of the lesions along the cavity wall. This inhibition was more effective at the occlusal side.

Dental Amalgam↗
PubMed1987

[Hemodynamic evaluation before and after balloon atrial septostomy in patients with transposition of the great arteries using pulsed Doppler echocardiography].

In nine patients with transposition of the great arteries, hemodynamic changes after the initial balloon atrial septostomy (BAS) were investigated using pulsed Doppler echocardiography and cardiac catheterization. Patients consisted of five males and four females, who ranged in age from zero to 82 days (median, one day). All but one who had ventricular septal defect had no associated cardiac anomalies other than patent ductus arteriosus. Prostaglandin E1 was administered before and after BAS to four patients who had hypoxemia. At cardiac catheterization, right and left atrial pressures and arterial oxygen partial pressure were measured. Using pulsed Doppler echocardiography, the time-velocity curve was recorded at the tricuspid and mitral valves, pulmonary artery, ascending aorta and interatrial septum. The maximum diastolic velocity was measured from the tricuspid and mitral valve time-velocity curves. The product of the time-velocity integral and heart rate was measured from the time-velocity recordings at the pulmonary artery and ascending aorta. The duration of the left-to-right shunt at the foramen ovale was measured and was normalized by corresponding R-R intervals on the electrocardiogram. After BAS, left atrial pressures and pressure gradients between both atria decreased significantly (p less than 0.01). Arterial oxygen partial pressure increased from 24.4 +/- 7.2 to 40.4 +/- 6.0 mmHg (p less than 0.01). The maximum flow velocity at the tricuspid valve increased significantly (p less than 0.01), but that at the mitral valve showed no significant change after BAS. The velocity time integral of the aorta increased significantly (p less than 0.01), but that of the pulmonary artery did not.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1986

Scoring method for identifying patients with Kawasaki disease at high risk of coronary artery aneurysms.

The beneficial effect of immunoglobulin in preventing coronary artery aneurysms in patients with Kawasaki disease is recognized, but immunoglobulin should be selectively given to patients at high risk for coronary lesions. The present study was designed to present a scoring method to evaluate the severity of Kawasaki disease in terms of coronary artery disease based on clinical and early laboratory findings. Seventy-eight patients who were admitted at 4 to 7 days of illness and who had received aspirin alone during the acute febrile period were separated into 2 groups according to significant coronary artery involvement, and possible related factors to the discrimination of the 2 groups were studied using multivariate analysis. Age at onset, C-reactive protein and platelet count contributed significantly to the discrimination, and from these 3 items a simple scoring system was devised to predict patients at high risk for coronary lesions. Retrospective study using this scoring method indicated that significant coronary artery disease was more often seen in patients predicted to be at high risk treated with aspirin, while no patients who received immunoglobulin had coronary lesions of moderate or severe degree. Thus, the present scoring method provides simple but clinically useful criteria for predicting patients at high risk of coronary artery disease, and immunoglobulin therapy for selected patients may reduce the significant coronary artery complications of Kawasaki disease.

Coronary Disease↗
PubMed1986

Doppler detection of tricuspid regurgitation following Kawasaki disease.

Between June 1984 and April 1985, five patients (4.2%) had tricuspid regurgitation detected on pulsed Doppler echocardiography among 119 patients with Kawasaki disease. The grade of tricuspid regurgitation was moderate in three and mild in two patients; conventional cardiac examinations revealed no evidence of this complication. All patients had associated coronary artery aneurysms except one, but no patients developed subsequent myocardial infarction. The occurrence of tricuspid regurgitation following Kawasaki disease has been considered to be causally related to the carditis, a frequent complication during the acute febrile period of the illness. The present data indicate that tricuspid regurgitation is an additional cardiovascular complication of Kawasaki disease and that Doppler echocardiography is useful in detecting this disorder.

Adult↗
PubMed1986

A new method for estimation of nerve conduction velocity distribution in the frequency domain.

Nerve conduction velocity (NCV) measurements have been widely used to assess the electrophysiological properties of peripheral nerves and to detect neuropathies at a subclinical stage. Conventional NCVs are usually expressed as the NCV for the fastest conducting fibers and the current standard methods do neither supply information about slower conducting fibers, nor detect information about individual fiber groups. We present a new analytical method, to estimate the distribution of conduction velocity (DCV), based upon spectral analysis of the wave forms of two compound action potentials (CAPs) recorded by surface electrodes from a nerve bundle. If the spectra of the two CAPs recorded at two different sites in response to supramaximal electrical stimulation at distances l1 and l2 are given as G11(omega) and G12(omega), the spectral representation of the latency distribution P12(omega) for the propagation distance l2 is expressed as follows: P12(l1 omega/l2) = [G11(omega)/G12(omega)]P12(omega), where omega is an angular frequency. We developed an algorithm that computes P12(omega) successively without using iterative calculation methods. Our estimation method is theoretically based upon the principle that the CAPs are recorded monopolarly to estimate the DCV, but in practical use, it is almost impossible to obtain appropriate CAP wave forms by monopolar recording methods, because of stimulation and muscle artefacts. In order to evaluate the efficacy of bipolarly recorded CAP wave forms for this computation algorithm, we examined the two CAP wave forms reconstructed by simulation techniques. We found that the difference between the monopolar and bipolar recording methods was reflected in the wave form extracted for the single fiber action potentials but not in the latency distribution. The distance between the bipolarly recorded electrodes (1.5 cm was the minimal distance used) did not affect the reproducibility of estimating the latency distribution. This new method is non-invasive and could be used for evaluation of peripheral neuropathies.

Action Potentials↗
PubMed1986

[Valvular lesions complicating Kawasaki disease: a Doppler echocardiographic evaluation].

Coronary artery aneurysms are the most frequent and important complication of Kawasaki disease, but valvular disease is less frequently observed. During the last three years, we have observed mitral regurgitation (MR) in nine (7.3%), aortic regurgitation (AR) in six (4.6%) and tricuspid regurgitation (TR) in five (4.2%) patients with Kawasaki disease. The diagnosis of valvular disease was confirmed by Doppler echocardiography in all patients. Cardiac murmurs typical of regurgitation were audible in approximately half the patients with MR and AR, and in only one with TR. By chest radiography, cardiomegaly was observed in five of nine patients with MR and in three of six with AR, but in none with TR. Similarly, the ECG finding of cardiac overload was observed in four patients with MR and in three with AR, but in none with TR. Thus, Doppler echocardiography proved very valuable for diagnosing valvular regurgitation in patients with Kawasaki disease. Other cardiovascular complications included coronary artery aneurysms in all except for only one patient with TR. Subsequent myocardial infarction was observed in three patients with MR and in two with AR. Valvular lesions complicating Kawasaki disease generally carry a good prognosis, without progression to stenotic valvular lesions. Although the exact mechanism of this complication is obscure, it is postulated that the valvular lesion results from myocardial infarction or from inflammation of the valvular leaflets or apparatus of the valve following carditis.

Child↗