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Biomedical subjects

M Okamoto

Publications and source records attributed to M Okamoto.

At least 1,063 records · Page 59Linked to original sources
PubMed1983

Purification and characterization of human pancreatic phospholipase A2 and development of a radioimmunoassay.

Human pancreatic phospholipase A2 was purified to homogeneity from pancreatic juice and a reliable radioimmunoassay for the enzyme was developed. The molecular weight of the enzyme as estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis was 14,000. Phosphatidylcholine was hydrolyzed well in an alkaline pH range, and the optimum activity was obtained at pH 9. Calcium ion was indispensable for activity. The enzyme was stable to heat treatment at 60 degrees C for 5 min. The radioimmunoassay system was highly sensitive, reproducible and specific. The dilution curves for the sera of patients with acute pancreatitis were parallel to the standard curve. In healthy individuals, serum phospholipase A2 concentrations ranged from 2.0 to 7.9 ng/ml, the average being 5.1 ng/ml (S.D.: 1.7). In patients with acute pancreatitis, significant elevations of serum phospholipase A2 contents were observed, and the highest value found was 4,000 ng/ml.

Antibody Specificity↗
PubMed1983

Mitral regurgitation in hypertrophic cardiomyopathy. Non-invasive study by two dimensional Doppler echocardiography.

Mitral regurgitation and its haemodynamic features were investigated non-invasively in cases of hypertrophic cardiomyopathy by means of two dimensional Doppler echocardiography. There were 28 patients, 14 of whom showed systolic anterior motion (SAM) of the mitral echo; the other 14 did not. The following results were obtained. (1) Mitral regurgitation was detected by the Doppler technique in all cases with systolic anterior motion of the mitral echo and in half of those without it. (2) Doppler signals of mitral regurgitation started immediately after the first heart sound. (3) Mitral regurgitant flow was often distributed from the entire mitral orifice over the entire or the posterior half of the left atrium in the cases with systolic anterior motion. In the cases without systolic anterior motion the regurgitation was usually localised near the mitral orifice. These features differ from those of regurgitation usually seen in rheumatic mitral valve disease and idiopathic mitral valve prolapse. (4) The Doppler technique and left ventriculography were equally efficient in detecting mitral regurgitation. (5) The early systolic component of the murmur of hypertrophic myopathy is considered to result in the main from concomitant mitral regurgitation, but not from turbulent blood flow in the left ventricular outflow tract, so that in cases with mitral regurgitation as a complication, mitral regurgitation may also contribute to the development of the midsystolic portion of the systolic murmur, while the main origin of this portion of the murmur is the left ventricular outflow obstruction.

Adult↗
PubMed1983

Studies on WF-3161, a new antitumor antibiotic.

WF-3161 is an antitumor antibiotic produced by a strain of fungus, Petriella guttulata. The antibiotic was purified by solvent extraction and a combination of silica gel and reverse phase column chromatography. The chemical structure of the antibiotic (C31H44N4O6, mp 181-183 degrees C) was found to be a cyclic tetrapeptide consisting of phenylalanine, leucine, pipecolinic acid and 2-amino-8-oxo-9,10-epoxydecanoic acid. WF-3161 inhibited the growth of Trichophyton asteroides. It prolonged survival period of mice bearing leukemia P-388 with a high therapeutic index.

Animals↗
PubMed1983

Affinity of 18,19-dihydroxydeoxycorticosterone and 18-hydroxy-19-nor-deoxycorticosterone to aldosterone receptor and their mineralocorticoid activity.

Affinity of 18,19-dihydroxydeoxycorticosterone (18,19-diOH-DOC) and 18-hydroxy-19-nor-deoxycorticosterone (18-OH-19-nor-DOC) to aldosterone receptor and their mineralocorticoid activity were evaluated. 18,19-DiOH-DOC (1 X 10(-6) M) did not show appreciable binding to the receptor and its relative potency as a mineralocorticoid was estimated to be less than 1/8,000 of that of deoxycorticosterone (DOC). 18-OH-19-nor-DOC bound to the receptor with an affinity similar to that of 18-hydroxydeoxycorticosterone (18-OH-DOC) or spironolactone. Its sodium retaining activity was 0.04 times as great as that of DOC and similar to that of 18-OH-DOC.

18-Hydroxydesoxycorticosterone↗
PubMed1983

Central pigmentary retinal dystrophy and its angiographic classification.

Twenty-one cases of central pigmentary retinal dystrophy were compiled and their clinical features were described. On the basis of fluorescein fundus angiography, these cases were classified into three types according to the changes in the choriocapillaris. In Type 1, the choriocapillaris showed annular or bow-shaped atrophy around the vascular arcade in the posterior pole of the fundus, but little change in the foveal region. Type 2 exhibited round or irregularly shaped atrophy of the choriocapillaris in the center of the posterior pole of the fundus. Type 3 had no atrophy of the choriocapillaris and showed only hyperfluorescence in the posterior pole of the fundus, due to damage of the retinal pigment epithelium. These types differed from each other not only from the morphological point of view, but also in other clinical findings that included age of onset, progression of visual impairment, pattern of color vision defects or recordability of the electroretinogram. It was discussed that central pigmentary retinal dystrophy consists of heterogenous conditions.

Adolescent↗
PubMed1983

[Measurement of four chambers' volumes and ventricular masses by cardiac CT examination].

Using cardiac computed tomography (CT), the "mean" volume of each cardiac chamber and both ventricular masses were calculated from summation of a sliced volume by ungated scans obtained using rapid sequential scanning covering the whole heart. Estimation of a normal value of each chamber's volume was attempted in 20 patients with ischemic heart disease and with normal heart function. The "mean" volume of the right atrium (RAMV), right ventricle (RVMV), and left atrium (LAMV) was 22.3 +/- 6.5, 40.3 +/- 6.5 and 28.7 +/- 8.2 ml/m2, respectively. In 54 patients with valvular heart diseases, each chamber's volume obtained by CT was compared with the grade of tricuspid regurgitation (TR) estimated by ultrasonic Doppler technique or the grade of mitral regurgitation (MR) by left ventriculography (LVG). The RAMV (234 +/- 119 ml/m2) and the RVMV (101 +/- 39 ml/m2) were markedly increased in patients with severe TR (grade 3 to 4) (p less than 0.01). The LAMV (487 +/- 231 ml/m2) was also increased in patients with severe mitral regurgitation (grade 3 to 4) (p less than 0.01). In 46 patients with valvular heart diseases, the LVMV by CT was well correlated with end-diastolic volume (EDV) obtained by LVG (r = 0.92), and the LVEDVs by ECG gated CT and by LVG showed a fairly good correlation (r = 0.95). CT examination was performed before and after surgery in 17 patients with MR or TR for evaluation of the change of chamber volumes. The mean reduction ratio (MRR) of the RAMV after tricuspid annuloplasty, the LVMV after mitral valve plasty, and the LAMV after left atrial plication was 44%, 41%, and 60%, respectively.

Cardiac Volume↗
PubMed1983

Effects of individual variations in drug elimination kinetics for production of pentobarbital physical dependence.

Many studies have suggested the importance of the rate of drug elimination in the development of pharmacodynamic tolerance and physical dependence to sedative-hypnotics. However, these studies usually compared drugs whose pharmacokinetic properties differed widely, e.g., short- vs. long-acting barbiturates. Accordingly, we investigated the relationship between individual variations in the rate of elimination of a single drug, pentobarbital, and the severity of physical dependence which developed during chronic pentobarbital administration. Animals were treated with Na pentobarbital according to the "maximally tolerable" dosing schedule described previously, twice a day for 35 days, and abruptly withdrawn. The relationship between chronic treatment variables (doses and blood concentrations of pentobarbital, peak and residual central nervous system depression scores), elimination half-lives and withdrawal intensity were explored. Withdrawal intensity was evaluated as overall withdrawal intensity ratings, the number and types of spontaneous withdrawal convulsions and lethality. Individual variations in the drug elimination half-lives related significantly to the severity of physical dependence produced by pentobarbital: the longer half-life, the more intense the production of physical dependence by pentobarbital.

Animals↗
PubMed1983

[Diastolic filling of the right ventricle in hypertrophic cardiomyopathy studied with 2-dimensional Doppler echocardiography].

Inflow pattern at the tricuspid orifice was examined using two-dimensional Doppler echocardiography. The cases examined consisted of 24 cases of hypertrophic cardiomyopathy (HCM), 10 cases of left ventricular hypertrophy (LVH) due to hypertension or aortic valvular stenosis and 23 healthy subjects. The right ventricular inflow pattern in HCM was characterized by a slow deceleration of a rapid filling wave, an increase in the duration of an inflow due to atrial contraction and an increased ratio of the peak velocity in atrial contraction phase to that in rapid filling phase (A/R). No definite difference was noted in the right ventricular inflow pattern between HCM with and without left ventricular obstruction. The abnormalities in the right ventricular inflow pattern in LVH were similar to those in HCM. The abnormal inflow patterns in HCM and LVH suggested a reduced distensibility of the right ventricle in early diastole and the compensatory augmentation of right atrial contraction. The changes in the deceleration of the rapid filling wave and A/R ratio were significantly correlated with interventricular septal thickness (base and papillary muscle levels) in cases with LVH. This result seemed to indicate that the changes in the right ventricular inflow are mainly resulted from the influence of hypertrophy of the interventricular septum on right ventricular function. There was hypertrophy of the interventricular septum in all cases of HCM and, in addition, that of the right ventricular anterior wall in some of them. The changes in the inflow pattern in HCM are also considered to be resulted from hypertrophy of the right ventricular anterior wall and the influence of hypertrophy of the interventricular septum on right ventricular function. However, in the cases of HCM, the extent of the changes showed no significant correlation with right ventricular anterior wall thickness and interventricular septal thickness. In HCM, hypertrophy of the interventricular septum and right ventricular free wall may coexist, and ventricular hypertrophy is often nonuniform and may exhibit disarrangement in myocardial architecture. Therefore, influential factors on the right ventricular inflow are considered to be more complicated in HCM than in LVH, resulting in the absence of significant correlation to the abnormal inflow mentioned above.

Adolescent↗
PubMed1983

Evaluation of the factors influencing the radiosensitivity of mouse ascites tumors.

Factors influencing the radiosensitivity of the newly established mouse ascites tumor TMT-3 line were studied. In vivo radiosensitivity of the tumor cells decreased with the progression of the growth phase in mice. Oxygen depletion was the major cause of the decreased radiosensitivity. Polarographic measurement of the oxygen dissolved in suspension of various cell densities suggested that high cell density such as in the ascites might well cause severe hypoxia. Humoral factors in the ascites and cell-to-cell contact had no effect on tumor cell radiosensitivity when the influence of the repair of potentially lethal damage was excluded.

Animals↗