[Effects of impurities on enzyme induction and toxicity in rats treated with 2,3,7,8-tetrachlorodibenzofuran].
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Animals↗
Biomedical subjects
Y Masuda
Publications and source records attributed to Y Masuda.
[A simply designed apparatus and its use for measuring vertical and horizontal motor activities in methamphetamine-treated mice].
A simple apparatus using the infrared ray, which can divide spontaneous motor activity (SMA) of mice into two behavioral components, a vertical movement (VM) and a horizontal movement (HM) was designed. VM and HM were evaluated by counting the number of times that infrared rays were blocked by the mouse in the activity cage [300(H) X 260(D) X 130(W) mm] with 9 infrared photo-couplers for measuring VM and one infrared photo-coupler for measuring HM. When methamphetamine (MAM) was subcutaneously administered to mice pretreated with saline (0.1 ml/10 g, sc) for 3 days, VM and HM were as follows: 1) At 0.1 mg/kg of MAM, the same level of activity was observed as with saline. 2) At 1.0 mg/kg of MAM, increased activity was noted. 3) At 10 mg/kg of MAM, a marked increase was noted, showing more enhancement of HM than VM, which had developed into a stereotyped behavior. In summary, this new apparatus was found capable of dividing the SMA of mice into the two behavioral patterns of VM and HM, and providing their measurements.
Animals↗
[Anesthesia for a cesarean section on a patient with hypertrophic obstructive cardiomyopathy (HOCM)].
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Anesthesia, Obstetrical↗
[Photoactivated contraction of the isolated dilator smooth muscle of the rat iris].
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Animals↗
Prevention of butylated hydroxytoluene-induced lung damage by diethyldithiocarbamate and carbon disulfide in mice.
Diethyldithiocarbamate (DTC) and carbon disulfide (CS2), at nearly equimolar doses (po), prevented mice from lung injury induced by butylated hydroxytoluene (BHT), as evidenced by suppression of increased lung weight and total DNA content as well as by histopathologic observations. CS2 pretreatment dose dependently decreased the amount of covalently bound [ring-14C]BHT to lung macromolecules in vivo. A slight, but significant, loss of lung GSH observed early after BHT administration was also prevented. The lung microsomal fraction exhibited NADPH-dependent covalent binding of BHT in vitro; this was inhibited completely by carbon monoxide and slightly by SKF-525A. This NADPH-dependent binding was suppressed in lung microsomes isolated from CS2-treated mice. CS2 also reduced various drug metabolizing enzyme activities and the cytochrome P-450 content of the lung microsomal fraction. These results support the metabolic activation hypothesis for BHT-induced lung damage, and the preventive action of CS2 and DTC may be due to an inhibition of this bioactivation step. Possible sites of the metabolic activation of BHT and its inhibition by CS2 are discussed.
Animals↗
The effects of neuronal uptake blockade on the cardiac responses to sympathetic nerve stimulation and norepinephrine infusion in anesthetized dogs.
In anesthetized dogs, cocaine ( COC ) was administered intravenously in order to block the neuronal uptake of norepinephrine (NE) by the heart. COC had relatively little effect on the magnitudes of the inotropic and chronotropic responses to sympathetic stimulation, but it did prolong the decay times, especially those of the chronotropic responses. The marked prolongation of the decay times of the chronotropic responses indicates that neuronal uptake must be the main mechanism for dissipating the adrenergic transmitter in the sinus node. However, this mechanism appears to be less important in the ventricular myocardium. At all dosage levels, COC increased the overflow of NE into the coronary sinus blood during cardiac sympathetic stimulation. The extraction of exogenously infused norepinephrine by heart tissue varied inversely with the dose of COC , indicating that the extent of neuronal uptake blockade increased with the dose. Nevertheless, NE overflow into the coronary sinus blood after a relatively large dose (5.7 mg/kg) of COC was less than that observed after a much smaller dose (0.5 mg/kg), suggesting that relatively large doses of COC also tend to inhibit the neuronal release of NE. These results indicate that the effects of COC on the cardiac responses to sympathetic stimulation depend on the balance between its influences on the release and dissipation of neurotransmitter in the neuroeffector gap.
Animals↗
Recent trend on the prevalence of tardive dyskinesia in Japan.
An epidemiological study was undertaken, taking a survey of 2,274 chronic schizophrenic patients hospitalized for 2 years or more in 17 mental institutions in Japan. The overall prevalence of tardive dyskinesia (T.D.) was 19.1%. The prevalence of TD differs considerably from one institution to the other, with a range of 0 to 36.1%. The longer the history of institution was, the higher the prevalence of TD. The prevalence showed a tendency to increase with increasing age. Long-term hospitalization concomitant with continuous neuroleptic medication seemed to play a role in the prevalence of TD. TD occurred with higher frequency in patients with somatic complications than in those without complications. Past drug history, including duration of treatment and responsible neuroleptics, has been considered to play an important role in the prevalence of TD. But, results of the present investigation showed that the present drug status might also influence on the appearance of TD. The facts obtained from the present study are of value to establish regimens mainly based on medical treatment for prediction and prevention of TD.
Adult↗
Determination of methylthio and methylsulphone polychlorinated biphenyls in tissues of patients with 'yusho'.
The liver, lung and mesenteric adipose tissue of three patients with 'yusho', polychlorinated biphenyl (PCB) poisoning, and two control persons were analysed for methylthio and methylsulphone metabolites of PCBs by gas chromatography with electron capture detection, gas chromatography-mass spectrometry and mass fragmentography. The tissues were shown to contain two congeners of methylthio PCBs with four chlorine atoms, and 16 congeners of methylsulphone PCBs with three, four, five or six chlorine atoms. The concentrations of methylthio PCBs in the liver, lung and adipose tissue of the yusho patients were 0.1-0.5, 0.2-1.4 and 0.5-1.0 micrograms/kg, respectively, and those of methylsulphone PCBs were 0.3-0.7, 1.0-2.5 and 0.7-1.0 micrograms/kg, respectively. The concentration ratios of methylthio and methylsulphone PCBs to unchanged PCBs were 1-2% in the liver, 4-8% in the lung and 0.1-0.2% in the adipose tissue for yusho patients, indicating that these metabolites accumulate slightly more in the lung and liver than in the adipose tissue, relative to PCBs. The tissue levels of the PCB metabolites in control persons were about one tenth of those in yusho patients.
Adipose Tissue↗
The rate of arterial blood pressure change as a factor in the hysteresis of the baroreceptor reflex.
We induced sinusoidal arterial blood pressure oscillations in anaesthetized dogs, and measured the resulting reflex changes in cardiac cycle length. The graphs of cardiac cycle length as a function of systolic arterial pressure displayed considerable hysteresis. The extent of the hysteresis and the direction around the loop varied with the frequency of the pressure oscillations. At relatively low frequencies (0.02 and 0.04 Hz) the loops were predominantly anticlockwise, whereas at higher frequencies (0.08 and 0.16 Hz) the loops were mainly clockwise in direction. In a second group of dogs we stimulated the transected vagus nerves with sequential ramp-like increases and decreases in voltage. The graph of the chronotropic response displayed a prominent anticlockwise hysteresis. Hence the anticlockwise hysteresis which was induced reflexly by cyclic oscillations of systemic arterial pressure is at least partly ascribable to an efferent vagal mechanism.
Animals↗
Depression and ventricular enlargement.
Compared with controls, 46 depressed patients showed increased ventricular-brain ratio (VBR). Patients with poor outcome, single episode, onset at 50 years or over, or without melancholia were found to have greater VBR than controls.
Adult↗
Hypotensive actions of some analogues of platelet-activating factor (PAF) with higher potencies than natural PAF.
Substituents on the nitrogen atom of the phosphorylcholine moiety of natural C16 platelet-activating factor (PAF) were modified or replaced by more bulky groups, and their hypotensive activities were examined with rats. As a result, it was found that N-methylpiperidine and N-methylpyrrolidine analogues were 3-10 times more potent than natural C16-PAF.
Animals↗
Effects of digoxin on the chronotropic responses to repetitive vagal stimulus bursts in the dog.
We studied the effects of digoxin on the chronotropic responses of the heart to repetitive bursts of vagal stimulation in chloralose-anesthetized dogs. The frequency of the stimulus bursts was increased linearly with time. Over a certain range of frequencies, the cardiac pacemaker became synchronized with the vagal stimulation in a 1:1 ratio of heart beats to stimulus bursts. Digoxin increased the range of cardiac cycle lengths over which 1:1 synchronization occurred during repetitive vagal stimulation. This increment in the range of synchronization varied directly with the dose of digoxin. Before digoxin was given, the range of cardiac cycle lengths over which synchronization occurred when the vagus nerve was stimulated with 10 pulses per burst was 272 +/- 50 (mean +/- SE) ms. However, after a cumulative dose of 120 micrograms/kg-1 digoxin had been given, the range of 1:1 synchronization increased to 396 +/- 32 ms. Digoxin did not appear to have a proportionately greater effect on those processes that take place in the phase of the cardiac cycle during which the pacemaker cells are maximally responsive than on those processes that occur in the phase of the cycle during which the pacemaker cells are minimally responsive. Therefore, we conclude that the augmented entrainment induced by digoxin is ascribable to its tendency to enhance the chronotropic response to vagal stimulation.
Anesthesia↗
The usefulness of x-ray computed tomography for the diagnosis of myocardial infarction.
Conventional and enhanced computed tomographic (CT) examinations were performed in 103 patients with myocardial infarction for evaluation of the diagnostic usefulness of CT. After intravenous bolus injection of contrast material, an initial filling defect and late enhancement of the infarcted myocardium appeared on the cardiac CT images. These two findings were direct evidence of myocardial infarction; the former was found mostly in the patient with recent myocardial infarctions, and the latter was recognized both in those with recent and those with "remote" infarctions. Wall thinning at the site of infarction was found by enhanced CT mostly in patients with anteroseptal or extensive anterior infarctions, and was rarely found in patients with inferoposterior infarctions. Left ventricular aneurysms and ventricular thrombi were found by enhanced CT in 39 and 23 of the 103 subjects, respectively, and the sensitivity of CT in detecting intracardiac thrombi was higher than that of two-dimensional echocardiography. Calcification of the myocardium and pericardial effusion associated with myocardial infarction were also detected by conventional nonenhanced CT. Thus, cardiac CT was found to be a useful test in evaluating patients with myocardial infarction.
Adult↗
Possible role of endothelium in the vasodilator response of rat thoracic aorta to platelet activating factor (PAF).
As the endothelium has an important role in the vasodilating effect of acetylcholine, we investigated the possible role of the endothelium in the vasodilating effect of platelet activating factor (PAF). Experiments were done on spirally cut rat thoracic aorta either containing or denuded of endothelial cells. It was demonstrated that relaxation by PAF and acetylcholine of pre-contracted strips required the presence of endothelial cells. The results strongly suggested the possible involvement of endothelium in the vasodilation produced by PAF as well as by ACh.
Acetylcholine↗
High accumulation of 2,3,4,7,8-pentachlorodibenzofuran to hepatic microsomes of rats.
The tissue and subcellular distributions of 14C-2,3,4,7,8-pentachlorodibenzofuran (PenCDF), one of the most important causal agents of yusho, were studied using rats. More than 60% of the radioactivity given orally was accumulated in the liver after 5 d and this high percentage persisted over a period of 3 weeks. Subcellular fractionation of the liver homogenate showed unusual separation by PenCDF-pretreatment, but the distribution of radioactivity was just parallel to those of cytochrome P-450 content and glucose-6-phosphatase (EC3.1.3.9) activity. Gas chromatographic analysis provided evidence that the extracts from the liver and its subcellular fractionations contained only unchanged PenCDF. Those results strongly suggest that PenCDF has some affinity to endoplasmic reticulum of rat liver.
Animals↗
Clinical features of rheumatic heart disease in Bangladesh.
The clinical features of 205 cases of rheumatic heart disease in Bangladesh, including unique two-dimensional echocardiographic findings, were reported, and these were compared with those of 387 Japanese cases. The percentage of mitral stenosis (MS), aortic valvular diseases including both aortic stenosis and aortic regurgitation (A), mitral stenosis with aortic valvular diseases (MS + A) were almost the same between the two countries, but that of mitral regurgitation (MR) was higher, mitral stenosis and regurgitation (MSR) was lower in Bangladesh. The mean age of the patients with mitral valvular diseases was very young and the incidence of atrial fibrillation was very low in Bangladesh. Males predominated over females in MS (male/female = 1.2/1) and the incidence of pulmonary hypertension in MS was higher in Bangladesh. A two-dimensional echocardiographic examination showed that the rough zone was heavily involved in the rheumatic process with having a narrow mitral valve orifice while the clear zone was relatively spared and pliable in many patients with MS in Bangladesh. In MR, posterior mitral leaflets were shortened and made immobile by its submitral complex which were also thickened, fused and shortened, and these resulted in a gap or non-coaptation of the two leaflets in many patients.
Adolescent↗
Noninvasive diagnosis of thrombus in the heart and large vessels--usefulness of two-dimensional echocardiography and X-ray CT.
The usefulness of two dimensional echocardiography (2-D echocardiography) and x-ray computed tomography (CT) for the diagnosis of thrombi in the cardiac cavity and large vessels was studied by comparing them with the findings of invasive methods. Among 56 subjects with mitral stenosis, left atrial thrombi were noted in 12 cases (16 regions) by CT and 8 cases (9 regions) by 2-D echocardiography. In 16 subjects who underwent operations, one false negative case by CT and 3 false negative and one false positive cases by 2-D echocardiography were found. In 80 subjects with myocardial infarction 2-D echocardiography, CT and left ventriculography (LVG) were performed at approximately the same time. Thrombi were detected in 10 subjects (12.5%) by 2-D echocardiography, in 15 (18.8%) by CT and in 14 (17.5%) by LVG. Although mural thrombi in abdominal aortic aneurysm were detected very easily, thin thrombi surrounding the false lumen of the dissecting aneurysm were not detected ultrasonographically. These thrombi were only detected by the enhanced CT. Our results show the usefulness of both methods for detecting thrombi in the heart and large vessels. CT can distinguish the thrombi more clearly than 2-D echocardiography, but 2-D echocardiography is performed more easily, safely and economically than CT.
Adult↗
The effects of diethyldithiocarbamate and carbon disulfide on acute nephrotoxicity induced by furan, bromobenzene and cephaloridine in mice.
In previous studies (Masuda and Nakayama, 1983), diethyldithiocarbamate (DTC) and carbon disulfide (CS2) have been found to be protective against acute nephrotoxicity induced by CHCl3 and 1,1-dichloroethylene in normal and CCl4-poisoned mice, and it has been suggested that the protective action of DTC and CS2 might be mediated through inhibition of bioactivation of these nephrotoxicants in the kidney. As an extension of these studies, similar experiments were undertaken with furan, bromobenzene and cephaloridine, other nephrotoxic agents that are also thought to require metabolic activation. DTC or CS2 prevented mice from suffering renal injury induced by furan and bromobenzene, as evidenced by suppression of elevations in plasma urea nitrogen concentration and kidney calcium content and of morphologic alterations. Cephaloridine nephrotoxicity, however, was not prevented. In CCl4-poisoned mice, furan nephrotoxicity was augmented, whereas bromobenzene and cephaloridine nephrotoxicity was suppressed. The augumented furan nephrotoxicity was also prevented by DTC or CS2. These observations suggest that furan, like CHCl3 and 1,1-dichloroethylene, may exert nephrotoxicity through active metabolites formed in the kidney. For bromobenzene and cephaloridine nephrotoxicity, a renal bioactivation mechanism is suspected. DTC and CS2 also protected against hepatotoxicity induced by furan and thiophene.
Animals↗