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Biomedical subjects

J Suzuki

Publications and source records attributed to J Suzuki.

At least 469 records · Page 26Linked to original sources
PubMed1990

Determination of left ventricular volume and mass with use of biphasic spin-echo MR imaging: comparison with cine MR.

In this study, the authors compared a new rapid spin-echo magnetic resonance (MR) imaging method, biphasic MR, with cine MR in the determination of left ventricular volume and mass in healthy volunteers. Biphasic spin-echo MR images covering the entire heart were obtained with use of the electrocardiogram R wave and the downslope of the T wave at both end diastole and end systole, respectively. Biphasic MR-determined values correlated well with small standard errors of the estimate (end-diastolic volume = 7.82 cm3, end-diastolic mass = 10.20 g, end-systolic mass = 10.08 g, ejection fraction = 2.62%) and were more reproducible. Cine MR-defined end-systolic volume was significantly larger (P less than .01) and ejection fraction was significantly smaller (P less than .005) than biphasic MR-determined values probably because of the uncertainty in isolating end systole with cine MR. Left ventricular volumes, mass, and ejection fraction are more accurately and reproducibly quantified in a more time-efficient manner with use of biphasic MR than with cine MR because of its significantly shorter image acquisition and reconstruction times.

Adult↗
PubMed1990

Stereotactic aspiration of thalamic hematoma. Overall results of 75 aspirated and 70 nonaspirated cases.

Among 145 cases of spontaneous thalamic hemorrhage, stereotactic aspiration of the hematoma was done in 75 cases in which the hematoma was greater than 6 ml and the limbs on the affected side could not be elevated. Thirty-one of 40 operated cases with a long axis greater than 3.3 cm were capable of returning to useful activity 6 months postoperatively (excellent to fair). The results 6 months from onset in the 145 cases were as follows: 43% excellent or good, 32% fair, 11% poor and 13% dead. These results appear to indicate that stereotactic aspiration can produce improvements in therapeutic results for cases of thalamic hemorrhage.

Activities of Daily Living↗
PubMed1990

Caloric nystagmus in three dimensions under otolithic control in rhesus monkeys. A preliminary report.

The caloric nystagmus of rhesus monkeys in the 'optimum' supine or prone position was recorded three-dimensionally using magnetic search coils. The horizontal component of the nystagmus was in the direction expected from the convection flow theory of Bárány. The torsional component changed its direction according to the side of caloric stimulation independent of head position with regard to gravity, i.e., counterclockwise nystagmus by right ear stimulation and clockwise nystagmus by left ear stimulation both in the supine or in the prone positions. The direction of the vertical component depended upon the head position and not upon the side of stimulation, i.e., up-beating nystagmus in the supine position and down-beating nystagmus in the prone position. The durations and the contours of slow phase velocity of the horizontal, vertical and torsional components were different from each other. The origins of the first phase of caloric nystagmus in three dimensions may be explained by activation of all the three semicircular canals. As for the second phase of caloric nystagmus in the supine or in the prone position, the torsional component was comparatively strong and lasted the longest among the three components. The second phase of caloric nystagmus was markedly modified by head position with regard to gravity. These findings suggest that it is the otolithic organs that determine the moving plane of second phase caloric nystagmus.

Animals↗
PubMed1990

Pharmacokinetics in chimpanzees of recombinant human tissue-type plasminogen activator produced in mouse C127 and Chinese hamster ovary cells.

Pharmacokinetics of recombinant tissue-type plasminogen activator (rt-PA) produced in mouse C127 cells (t-PA(C127] and Chinese hamster ovary cells (t-PA(CHO] was investigated in chimpanzees. rt-PA was administered via a constant rate i.v. infusion for 60 min, and t-PA concentration and activity in plasma were measured during and after infusion. The noncompartmental parameters were calculated according to the moment analysis method, and a population pharmacokinetic analysis was performed to obtain the mean and interindividual variability of the pharmacokinetic parameters. The mean residence time of t-PA(C127) was significantly longer and the total body clearance was significantly less than that of t-PA(CHO). t-PA(C127) has an alpha-galactosyl moiety in its carbohydrate chains, whereas such a structure is not found in t-PA(CHO). These results demonstrate that two preparations of rt-PA's with different carbohydrate structures show different pharmacokinetics, and suggest that the carbohydrate structure can affect the efficiency of hepatic uptake of t-PA. A possible mechanism is an interaction of t-PA(C127) with the natural anti-alpha-galactosyl antibody. The anti-alpha-galactosyl antibody level in plasma decreased in association with the plasma levels of t-PA(C127) but was unaffected by t-PA(CHO) levels.

Animals↗
PubMed1990

Specificity of human natural antibody to recombinant tissue-type plasminogen activator (t-PA) expressed in mouse C127 cells.

A natural antibody with binding specificity for recombinant tissue-type plasminogen activator (t-PA) expressed in mouse C127 cells was present in almost all disease-free humans and patients with thrombotic disease examined. This antibody was specific for a carbohydrate, alpha 1-3-linked galactose residue, and was isolated by affinity chromatography using Synsorb 90 coupled with the glycosidic epitope Gal alpha 1-3Gal beta 1-4Glc-R as an immunoadsorbent. The evaluation of various glycoproteins for ability to bind the purified antibody in ELISA demonstrated that not only recombinant t-PA from C127 cells but also recombinant erythropoietin (EPO) and recombinant protein C produced in C127 cells have alpha 1-3-linked galactose residues on their sugar side chains. This anti-alpha-galactosyl antibody also interacted with natural t-PA from human vascular trees (vascular t-PA) and placenta (placenta t-PA), but not to melanoma t-PA, recombinant t-PA, EPO or protein C expressed in Chinese hamster ovary (CHO) cells.

Animals↗
PubMed1990

Cardiac magnetic resonance imaging in evaluation of anatomical structure and function of the ventricles.

Cardiac magnetic resonance imaging (MRI) is being widely employed for evaluation of cardiovascular anatomies and functions. However, the indications for cardiac MRI to obtain information which cannot be obtained using other conventional methods have not yet been determined. To demonstrate of usefulness of MRI in delineating the apex of the left ventricle and free wall of the right ventricle, end-diastolic short axis MRI images were obtained in 20 patients with apical hypertrophy and in 9 normal volunteers. To compare the accuracy of estimations of left ventricular volumes obtained using the modified Simpson's method of MRI with that using the MRI area length method, 19 patients, in whom left ventriculography had been performed, were studied. The apex of the left ventricle was evaluated circumferentially and distribution of hypertrophied muscles was defined. Sixty-five percent of the length of the right ventricular free wall was clearly delineated. Correlation coefficients of the ejection fraction between MRI and angiography were 0.85 with the modified Simpson's method of MRI, and 0.62 with the area length method of MRI. Three themes were chosen to demonstrate good clinical indications for cardiac MRI.

Cardiac Volume↗
PubMed1990

[Antihypertensive effect of betaxolol, a cardioselective beta-adrenoceptor antagonist, in experimental hypertensive rats].

Betaxolol is a highly selective beta 1-adrenoceptor antagonist without intrinsic sympathomimetic activity. In this study, the antihypertensive effect of betaxolol was investigated in experimental hypertensive rats; and the antihypertensive mechanism was also studied. Betaxolol (1 and 10 mg/kg, p.o.) produced acute hypotensive effects in conscious spontaneously hypertensive rats (SHR), renal hypertensive rats, deoxycorticosterone/saline hypertensive rats and normotensive rats. The effect was particularly marked in SHR. Furthermore, daily oral administration of betaxolol to SHR for 3 weeks showed sustained antihypertensive effects without producing tolerance. In pithed rats, the pressor response induced by an electrical stimulation of the spinal cord was inhibited by both betaxolol and atenolol. However, only betaxolol reduced the pressor response to norepinephrine. These findings suggest that a certain relaxing effect on peripheral vascular beds in addition to inhibition of presynaptic beta-adrenoceptors may contribute to the antihypertensive mechanism of betaxolol.

Administration, Oral↗
PubMed1990

[Antihypertensive effect of betaxolol, a cardioselective beta-adrenoceptor antagonist, in renal hypertensive dogs].

The antihypertensive effect of betaxolol, a highly selective beta 1-adrenoceptor antagonist, was investigated in renal hypertensive dogs, and the mechanism was also studied. A single oral administration of betaxolol (1 and 10 mg/kg) lowered blood pressure dose-dependently. The hypotensive effect of betaxolol was enhanced by daily oral administration for 10 days. In anesthetized dogs, intraarterial injection of betaxolol produced a dose-dependent increase in femoral artery flow; and in this test, betaxolol was 3 times less potent than papaverine. The increase in blood flow with betaxolol was not affected by pretreatment with propranolol. These findings indicate that a certain vasodilating activity may contribute to the antihypertensive mechanism of betaxolol.

Adrenergic beta-Antagonists↗
PubMed1990

Effects of betaxolol on cardiohemodynamics and coronary circulation in anesthetized dogs: comparison with atenolol and propranolol.

Effects of betaxolol, a cardioselective beta-adrenoceptor antagonist, on cardiohemodynamics and coronary circulation were investigated in two kinds of anesthetized open-chest dog preparations in comparison with those of atenolol and propranolol. When administered intravenously, betaxolol, atenolol and propranolol produced dose-dependent decreases in the heart rate (HR), maximum left ventricular dP/dt [+)dP/dt), cardiac output (CO) and mean arterial pressure (MAP). Although all three drugs were almost equipotent in decreasing HR, betaxolol was much less potent than atenolol and propranolol in decreasing (+)dP/dt. Betaxolol decreased the total peripheral resistance (TPR), whereas atenolol and propranolol increased it. In another series of experiments, when administered intravenously, betaxolol, atenolol and propranolol all produced a decrease in the myocardial oxygen consumption (MVO2) and an increase in the atrioventricular conduction time (AVCT). All three drugs were nearly equipotent in decreasing MVO2, although betaxolol was less potent than the other two drugs at higher doses (greater than 300 micrograms/kg). Prolongation of AVCT with propranolol was stronger than those with betaxolol and atenolol. These results suggest that, unlike atenolol and propranolol, the decrease in TPR as well as beta 1-adrenoceptor blockade may be responsible for both the hypotensive effect of betaxolol and the decrease in MVO2 with betaxolol. The result that the cardiodepressant effect of betaxolol was much less potent than those of atenolol and propranolol suggests that betaxolol would be more beneficial than the others in the treatment of ischemic heart disease.

Animals↗
PubMed1990

Cysteine protease in bovine milk capable of hydrolyzing casein as the substrate and elevation of the activity during the course of mastitis.

Cysteine protease was found to be present in bovine milk that catalyzed casein as the substrate. The protease was activated by reducing agents such as 2-mercaptoethanol and inhibited by monoiodoacetic acid, but not affected by the addition of phenylmethylsulfonyl fluoride, calcium or ethylene glycol bis (beta-aminoethyl)-N,N,N',N'-tetraacetic acid. The protease activity was linear as a function of protein amount and incubation time, and showed maximum at pH 6.0. By Sephacryl S-200 chromatography, at least two types of cysteine proteases having molecular weights of 45 kDa and more than 150 kDa were detected. The activity was increased in mastitic milk, and well correlated with the stages of mastitis, as indicated by the California mastitis test, somatic cell count and protein concentration. These results suggested that cysteine protease(s) is involved in the pathogenesis of mastitis.

Animals↗
PubMed1990

Effects of X-irradiation alone and in combination with ACNU on human glioblastoma cells in vitro.

The combined effects of x-irradiation and 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloro-ethyl)-3-nitrosourea (ACNU) on multicellular glioblastoma A-7 spheroids were analyzed by means of cell survival and dose-response curves. The actual dose-response curve for small spheroids was almost identical to that estimated from the cell survival curve. It was strongly suggested that a small number of radiation-resistant cells, which were not detected in the cell survival curve, were present in large spheroids with central necrosis. The enhancing effect of ACNU was greater with large spheroids than with monolayer cells or small spheroids. A possible explanation for this is that ACNU is higher effective against the few radiation-resistant cells that may be present in larger spheroids.

Cell Line↗
PubMed1990

Follow-up study on ruptured aneurysms treated by wrapping.

The authors experienced 1903 cases of ruptured aneurysm between 1961 and 1986. Most cases were treated by clipping or ligating the aneurysmal neck. However, these procedures were impossible in 52 cases (2.7%), for which wrapping alone (21 cases), aneurysmal body clipping and wrapping (11 cases), or body ligation and wrapping (20 cases) was performed. We studied the long-term results in 44 of these 52 cases. Rerupture occurred in only two cases with incomplete wrapping. We concluded that complete wrapping, and wrapping of residual portions following aneurysmal body clipping or body ligation produce favorable results.

Adolescent↗
PubMed1990

Cine MR imaging of valvular heart disease: display and imaging parameters affect the size of the signal void caused by valvular regurgitation.

The effects of display and imaging parameters on the measured size of the signal void representing valvular regurgitation on cine MR imaging were examined. Sixteen patients with valvular regurgitation were studied. Six cine acquisition modes were evaluated in five patients. Echo times (TEs) (8, 12, and 17 msec) and flip angles (30 degrees and 50 degrees) were varied. The variable display parameters were [Z x (blood pool signal intensity - lung signal intensity)] at window width (Z = 0.75, 1.00, 1.25) and (Y x window width + lung signal intensity) at window level (Y = 0.00, 0.25, 0.50). The area of the signal void was significantly (p less than .01) affected by the window level (2.7 +/- 0.8 cm2 at Y = 0.00, 4.4 +/- 1.1 cm2 at Y = 0.25, and 5.6 +/- 1.4 cm2 at Y = 0.50) and window width (3.6 +/- 0.9 cm2 at Z = 0.75 and 4.9 +/- 1.1 cm2 at Z = 1.25). With standardized display parameters, TE influenced the area (3.3 +/- 1.1 cm2 at 8 msec and 7.8 +/- 1.5 cm2 at 12 msec; p less than .01). Variations in the value of TE and display settings cause differences in the measured area of the regurgitant signal void. Quantification of valvular regurgitation by cine MR imaging requires strict standardization of display and imaging parameters.

Adult↗
PubMed1990

18F-fluoro-2'-deoxyuridine as a tracer of nucleic acid metabolism in brain tumors.

The value of 18F-fluoro-2'-deoxyuridine (18F-FUdR) as a tracer for nucleic acid metabolism was studied using an experimental rat brain-tumor model. The 18F activity in the tumor tissue 45 minutes after intravenous injection of 18F-FUdR was about 12 times higher than that in the contralateral cortex. Double-labeled autoradiography with 18F-FUdR and 14C-thymidine revealed similar brain-tumor images. In contrast, an autoradiographic comparison of 18F-FUdR with 14C-aminoisobutyric acid, which reveals the impairment of the blood-brain barrier, showed very different images. Also, the 18F radioactivity in the tumor tissue was at a constant level for 30 to 120 minutes, whereas a notable increase in 18F activity with time was observed in nucleotides and acid-insoluble fractions. These results suggest that the distribution pattern of 18F-FUdR closely correlates with the metabolism of nucleic acid and that this drug could be a useful tracer for positron emission tomography.

Animals↗
PubMed1990

[Paradoxical left ventricular blood flow during the isovolumic relaxation period in non-obstructive hypertrophic cardiomyopathy: Doppler and M-mode echocardiographic study].

The left ventricular blood flow pattern during the isovolumic relaxation period was investigated in 17 patients with apical hypertrophy (mean 54 +/- 8 years) and 30 with asymmetric septal hypertrophy without left ventricular outflow obstruction (mean 54 +/- 14 years). Thirty-five age-matched normal subjects served as controls (mean 51 +/- 10 years). All cases were examined by pulsed Doppler echocardiography simultaneously with phonocardiography. In all the control subjects, an apically-directed flow was observed, which occurred simultaneously with the onset of the second heart sound. In contrast, a basally-directed flow was detected during the isovolumic relaxation period in 13 patients (76%) with apical hypertrophy and in 28 (93%) with asymmetric septal hypertrophy. In these cases, an apically-directed flow was often observed before the second heart sound. Standard M-mode echocardiography revealed a significant increase in the left ventricular short-axis dimension at the base during the isovolumic period in patients with hypertrophic cardiomyopathy, while the normal controls showed no significant change. Moreover, peak velocity of the basally-directed flow correlated significantly with the rapidity of dilatation of the basal dimension (r = 0.61, p less than 0.01). Thus, this basally-directed blood flow in the left ventricle during the isovolumic relaxation period may be caused by the asynchronous left ventricular dilatation during the isovolumic period.

Adult↗