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Biomedical subjects

Y Masuda

Publications and source records attributed to Y Masuda.

At least 901 records · Page 50Linked to original sources
PubMed1981

[Measurement of cardiac volume by computed tomography (author's transl)].

Noninvasive cardiac volume measurement by computed tomography (CT) was attempted in this study. It was found that non-gated CT images were very close to the end-diastolic images by ECG-gated CT. Ten to fifteen non-gated scannings were obtained serially from the upper atria to the left diaphragm in 9 normal subjects and 72 patients (6 hypertensives, 7 aortic valvular diseases, 22 mitral valvular diseases, 5 shunt lesions and 33 ischemic heart diseases). To demarcate each chamber, contrast enhancement CT was performed by drip infusion in most cases, but it was done by 4-6 times bolus injections at the level of the left ventricle (LV) to visualize LV lumen in ischemic cardiac patients who had ventriculography. The volume was calculated by summing each slice's volume which was obtained from the area times slice thickness (Fig. 2). The total cardiac volume and the volume of each chamber (LA, RA, RV and LV) were calculated. The interventricular septum and LV wall were included into LV volume. There was a good relationship (r = 0.90) between the total cardiac volume by CT and that by chest X-ray (PA and lateral views) (Fig. 4). Each volume by CT in 9 normal subjects was: 353 +/- 30 ml/m2 in total, RA: 53 +/- 17 ml/m2, LA: 54 +/- 21 ml/m2, RV: 90 +/- 15 ml/m2, and LV: 123 +/- 15 ml/m2 (mean +/- SD), respectively, and an increment of each volume was shown according to the hemodynamic features of various heart diseases: the total volume was increased significantly in valvular disease (Fig. 5), RA and RV volumes in mitral valvular disease with tricuspid regurgitation and ASD (Figs. 6, 7) LA volume in mitral valvular disease and shunt lesion (Fig. 8) and LV volume in aortic valvular disease and mitral regurgitation (Fig. 9). Between the left ventricular lumen volume by Ct and its end-diastolic volume by ventriculography (area-length method), there was a good relationship (r - 0.81) in 17 cases without cardiac aneurysms out of 22 ischemic cardiac patients examined by ventriculography (RAO and LAO views) (Fig. 11). The cardiac CT was found very useful for measurements of cardiac volume, since it is noninvasive and quite simple yet reasonably accurate.

Adult↗
PubMed1980

The effects of cocaine, chlorpheniramine and tripelennamine on the cardiac responses to sympathetic nerve stimulation.

The effects of cocaine (COC), chlorpheniramine (CHL), and tripelennamine (TRI) on the cardiac responses to sympathetic neural stimulation were compared in open-chest, anesthetized dogs. The amplitudes of the chronotropic responses were not significantly altered by any of these drugs. Similarly, the amplitudes of the inotropic responses were not affected significantly by either COC or TRI, but they were increased moderately by CHL. All three drugs prolonged the inotropic and especially the chronotropic responses. CHL and TRI, in addition to being antihistaminics, are inhibitors of the neuronal uptake of norepinephrine. Therefor, the similarity of the effects of CHL, TRI, and COC on the cardiac responses to sympathetic stimulation is probably ascribable to their inhibitory activities on the neuronal uptake mechanism.

Animals↗
PubMed1980

A case of congenital hepatic fibrosis: usefulness of hepatobiliary scintigraphy.

A case of operatively proven congenital hepatic fibrosis was studied by scintigraphy with Tc-99m-phytate and Tc-99m-Pl (a hepatobiliary radiopharmaceutical). Two focal defects were recognized in the liver on the colloid liver scintigram. Ultrasound and contrast angiography suggested that the two focal defects were cystic lesions. Radionuclide hepatobiliary imaging was performed with Tc-99m-Pl, since intravenous cholangiography was unsatisfactory. One focal defect was proved to be a dilated intrahepatic bile duct and another was found to be cyst. Radionuclide hepatobiliary imaging with Tc-99m-Pl proved to be very useful in identifying dilated intrahepatic bile ducts in this patient as well as in following the progress of this disease.

Adult↗
PubMed1980

Differential antagonisms of anticonvulsants to various components of maximal seizures induced by electroshock or pentylenetetrazol in mice.

Effects of antiepileptic drugs on various components (TF: tonic extension of forelimb, TH: tonic extension of hindlimb and CL: clonic convulsions or MCL: myoclonus) of maximal seizures induced by electroshock or pentylenetetrazol in mice were examined in order to classify these drugs. In addition, experiment was conducted similarly on the new anti-convulsant agent, 3-sulfamoylmethyl-1,2-benzisoxazole (AD-810), in order to assess this compound on the basis of the results with clinically useful antiepileptic drugs. From the results obtained in the present study, irrespective of the method, i.e. chemically or electrically induced seizures, anticonvulsant drugs tested can be classified into four main groups; 1) drugs (trimethadione, ethosuximide, nitrazepam, diazepam, erthotoin and metharbital) with an effect to antagonize all the whole seizure components. (TF, TH and CL or MCL) in an almost same antagonism, 2) drugs (phenacemide, dipropylacetate, pheneturide, acetylpheneturide and phenobarbital) which inhibit all forms of seizures at relatively dissociated doses for the prevention of each component of seizures, 3) drugs (diphenylhydantoin and carbamazepine) which selectively abolish both components (TF and TH) of tonic seizures, and 4) drugs (acetazolamide, sulthiame and primidone) exclusively blocking TH of tonic seizures. AD-810 demonstrated an antagonistic effect on tonic seizures but no on clonic ones with the same manner as seen with diphenylhydantoin and carbamazepine.

Animals↗
PubMed1980

Comparative studies on the hepatotoxic actions of chloroform and related halogenomethanes in normal and phenobarbital-pretreated animals.

Hepatotoxic action of CHCl3 was examined biochemically by comparing with those of CCl4 and other related halogenomethanes using normal and phenobarbital (PB)-pretreated animals. In the later stage (24 hr), in mice, PB pretreatment augmented CHCl3-induced liver damage as evidenced by an enhancement of elevation of plasma transaminase activities and a parallel rise in liver triglyceride content. In the earlier stage (1 hr), in normal rats, CCl4 (1.0 ml/kg, i.p.) decreased microsomal glucose-6-phosphatase (G-6-Pase) activity and cytochrome P-450 content, whereas no significant effect was observed with the same dose of CHCl3. PB pretreatment produced a significant loss of both enzymes by CHCl3, and enhanced the loss of cytochrome P-450 induced by CCl4, while G-6-Pase activity was little affected by CCl4 in PB-pretreated rats. Both hepatotoxins increased liver malondialdehyde (MDA) content. Some of these early changes in vivo were reproduced in the lipid peroxidation system in vitro. Diethyldithiocarbamate suppressed various toxic manifestations induced by CHCl3 in PB-pretreated rats, but did not protect against the loss of cytochrome P-450 induced by CHCl3 or CCl4. These results suggest that lipid peroxidation hypothesis proposed for CCl4 hepatotoxicity may be applied to the case of CHCl3 though there exist some qualitatively different characteristics between these hepatotoxins, and that the mechanisms of the loss of microsomal G-6-Pase and cytochrome P-450 by either of these hepatotoxins might be different.

Animals↗
PubMed1980

3-Sulfamoylmethyl-1,2-benzisoxazole, a new type of anticonvulsant drug. Electroencephalographic profile.

Effects of 3-sulfamoylmethyl-1,2-benzisoxazole (AD-180) were examined electroencephalographically (EEG) on seizure activities induced by several means in rats and cats. AD-810 depressed the cortical focal seizure induced by electrical stimulation of the visual cortex at doses ineffective against the thalamic and hippocampal after-discharges in cats. AD-810 suppressed both interictal spikes and secondary generalized seizures (SGS), induced by cortical application of tungstic acid gel, in intact and decerebrated rats. Suppression of the spikes and SGS by AD-810 was also observed in cats with the epileptogenic foci produced by cortical freezing. Neither spontaneous EEG pattern nor EEG arousal response was modified with AD-810. It is suggested that AD-810 supresses the epileptogenic focus activity in the cortex and blocks the seizure propagation from the cortex to the subcortical structures through the effects on the cortex.

Animals↗
PubMed1980

3-Sulfamoylmethyl-1,2-benzisoxazole, a new type of anticonvulsant drug. Pharmacological profile.

The anticonvulsant and neurotoxic properties of 3-sulfamoylmethyl-1,2-benzisoxazole (AD-810) have been demonstrated. AD-810 suppressed electrically and chemically induced maximal seizures but did not prevent minimal seizures in experimental animals. In rats, rabbits and dogs, the anticonvulsant activity of AD-810 against maximal electroshock seizures was more potent than those of diphenylhydantoin and carbamazepine. In rats, AD-810 showed more rapid onset as well as longer duration of anticonvulsant activity than the above two drugs. The anticonvulsant effect of AD-810 was reduced but not abolished by reserpine. No tolerance developed to the anticonvulsant action of AD-810 by consecutive treatment. The compound showed much less neurotoxicity and lethal toxicity than the existing antiepileptic drugs for grand mal, and also showed the least hypnotic effect by itself or by combination with hexobarbital. Thus, AD-810 possesses a profile of anticonvulsant activity most similar to that of diphenylhydantoin or carbamazepine, providing a high protective index as well as other favorable properties.

Animals↗
PubMed1980

The effects of cocaine and metanephrine on the cardiac responses to norepinephrine infusions.

In open-chest, anesthetized dogs, the effects of blocking the neuronal and extraneuronal uptake mechanisms for norepinephrine on the inotropic and chronotropic responses to norepinephrine infusion were studied. Cocaine, a neuronal uptake blocking agent, potentiated and prolonged the inotropic and chronotropic responses. The chronotropic responses were more prolonged than the inotropic responses. Conversely, metanephrine, an extraneuronal uptake blocking agent, neither potentiated nor prolonged the inotropic and chronotropic responses. Hence, it appears that the neuronal uptake mechanism plays a major role in the sympathetic regulation of the heart, but that the extraneuronal uptake mechanism plays only a minor role. A pronounced interaction between the two uptake mechanisms was observed on the tendency to prolong the inotropic and chronotropic responses, such that the effects of combined blockade were much greater than the sum of the effects produced by separate blockade of the individual uptake mechanisms. However, no such interaction was observed with respect to the magnitudes of the responses.

Animals↗