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Biomedical subjects

Y Masuda

Publications and source records attributed to Y Masuda.

At least 775 records · Page 43Linked to original sources
PubMed1985

Promotion of the selective lymphatic delivery of cyclosporin A by lipid-surfactant mixed micelles.

The absorption of an immunosuppressive drug, cyclosporin A (CsA), with the aid of lipid-surfactant mixed micelles from the rat gastrointestinal (GI) tract and lymphatic delivery were studied. The administration of CsA in oily solution, sesame oil or linolic acid, into the rat duodenum indicated a small amount of CsA both in the plasma and lymph for about 6 h. The administration of CsA in the mixed micellar solution composing of linolic acid and HCO-60, polyoxyethylated (60 mol) hydrogenated castor oil, accelerated the absorption of CsA from the GI tract, and CsA was delivered into the lymphatics with an extremely high selectivity.

Animals↗
PubMed1985

Accumulation, excretion and effects on hepatic enzymes of polychlorinated quaterphenyl congeners in rats.

Six skeletal congeners of polychlorinated quaterphenyls (PCQs), namely polychlorinated o-quaterphenyl (2,2'-PCQ), 2,3'-diphenylbiphenyl (2,3'-PCQ), 2,4'-diphenylbiphenyl (2,4'-PCQ), m-quaterphenyl (3,3'-PCQ), 3,4'-diphenylbiphenyl (3,4'-PCQ) and p-quaterphenyl (4,4'-PCQ), were orally administered to Wistar rats at a dose of 10 mg/rat. On the 5th day after administration of PCQs, the rats were examined for accumulation of PCQ congeners, hepatic enzyme activities and organ weight changes. Accumulation of 3,3'-PCQ, 3,4'-PCQ and 4,4'-PCQ were 1.5-3.2% of dose in the liver, while those of 2,2'-PCQ, 2,3'-PCQ and 2,4'-PCQ were only 0.1 to 0.2%. The amount of 4,4'-PCQ accumulated in the mesenteric adipose tissue, 20 micrograms/rat, was much higher than those of other PCQ congeners. Large amounts of the PCQ congeners administered were excreted in the feces on the first day, accounting for 96 to 98% of dose for 2,2'-PCQ and 4,4'-PCQ, and 55 to 75% for the other PCQ congeners, and the daily excretions of PCQs after the second day were very small, less than 10% of the dose. Benzo [a] pyrene 3-hydroxylase activity was significantly depressed by the treatment with 3,3'-PCQ, 3,4'-PCQ and 4,4'-PCQ, contrasting to the toxic congeners of polychlorinated biphenyls and dibenzofurans which enhanced markedly this enzyme activity. DT-Diaphorase activity was also depressed by the treatment with 2,3'-PCQ, 2,4'-PCQ and 3,4'-PCQ. Significant atrophy of the thymus was observed by the treatment with 4,4'-PCQ.

Adipose Tissue↗
PubMed1985

Suppression of phenacetin-induced methemoglobinemia by diethyldithiocarbamate and carbon disulfide and its relation to phenacetin metabolism in mice.

Oral pretreatment with diethyldithiocarbamate (DTC) and carbon disulfide (CS2) prevented mice from methemoglobinemia induced by phenacetin. This treatment resulted in marked elevation of plasma p-phenetidine concentrations, prolongation of phenacetin levels, and lowering of N-acetyl-p-aminophenol and p-aminophenol levels. Both DTC and CS2 also suppressed p-phenetidine-induced methemoglobinemia with a delay in plasma p-phenetidine disappearance. In vitro, methemoglobin formation by p-phenetidine was decreased in liver microsomes isolated from DTC- or CS2-treated mice. The liver microsomal phenacetin and p-phenetidine O-deethylation activities and p-phenetidine N-hydroxylation activity decreased 1 h after administration of DTC or CS2, whereas deacetylation of phenacetin and N-acetyl-p-aminophenol by microsomes and acetylation of p-phenetidine by a soluble fraction from a liver homogenate were scarcely affected. The suppression of methemoglobinemia by DTC and CS2 may result from an inhibition of metabolic conversion of p-phenetidine to methemoglobin-forming substances such as N-hydroxy-p-phenetidine which is of most importance, p-aminophenol and 2-hydroxy-p-phenetidine by the microsomal cytochrome P-450-containing monooxygenase system in the liver.

Animals↗
PubMed1985

Advance of cardiac computed tomography--functional evaluation of the cardiovascular system.

The validity of X-ray CT in the functional diagnosis of several cardiovascular diseases was evaluated. CT was useful for assessing the amount and the characteristics of intrapericardial fluid, and it was also useful for the diagnosis of cardiac tamponade and constrictive pericarditis. A dynamic scan was found to be useful for determining the location, direction and the magnitude of intracardiac shunts, and for differentiating the true lumen from the false lumen in dissecting aortic aneurysms. As direct evidence of myocardial infarction, a filling defect in the infarcted area and late enhancement of the same area on delayed scan were noted. Regional wall motion abnormalities could be demonstrated by ECG gated CT, and other findings such as myocardial thinning, ventricular aneurysm and mural thrombi in the infarcted area were documented.

Aortic Aneurysm↗
PubMed1985

PCB and PCDF congeners in the blood and tissues of yusho and yu-cheng patients.

Polychlorinated biphenyl (PCB) poisonings occurred in western Japan, where it is called yusho, in 1968, and in central Taiwan, where it is called yu-cheng, in 1979. The average concentrations of PCBs in the adipose tissue, liver and blood of yusho patients and in the blood of yu-cheng patients were 1.9 ppm, 0.08 ppm, 6.7 ppb and 99 ppb, respectively. Seven PCB congeners, such as 2,4,5,3',4'-pentachloro-, 2,3,4,3',4'-pentachloro-, 2,4,5,2',4',5'-hexachloro-, 2,3,4,2',4',5'-hexachloro-, 2,3,4,5,3',4'-hexachloro-, 2,3,4,5,2',4',5'-heptachloro- and 2,3,4,5,2',3',4'-heptachloro biphenyls were identified in the blood and tissues of patients with yusho and yu-cheng and controls. The concentration of 2,3,4,5,3',4'-hexachlorobiphenyl was comparatively higher in the patients than in controls. The concentrations of polychlorinated dibenzofurans (PCDFs) in the adipose tissue and liver of yusho patients were 6 to 13 ppb and 3 to 25 ppb, respectively, while no PCDFs were detected in the controls. Major PCDF congeners identified in the tissues and blood of yusho and yu-cheng patients were the 2,3,6,8-tetrachloro-, 2,3,7,8-tetrachloro-, 1,2,4,7,8-pentachloro-, 2,3,4,7,8-pentachloro- and 1,2,3,4,7,8-hexachlorodibenzofurans (DFs), of which the 2,3,4,7,8-pentachloro compound was predominant. The concentrations of methylthio-PCB in the liver, lung and adipose tissue of yusho patients were 0.1 to 0.5, 0.2 to 1.4 and 0.5 to 1.0 ppb, respectively, and those of methysulfone PCBs were 0.3 to 0.7, 1.0 to 2.5 and 0.7 to 1.0 ppb, respectively. Some of the major peaks of the PCB methylthio and methylsulfone derivatives were identical in gas chromatographic retention times with those of 4-methylthio- and 4-methylsulfone-2,5,2',5'-tetrachlorobiphenyl PCDFs, especially 2,3,4,7,8-pentachloro DF, appear to be mainly responsible in the poisonings.

Benzofurans↗
PubMed1985

Inducing potency of aryl hydrocarbon hydroxylase activity in human lymphoblastoid cells and mice by polychlorinated dibenzofuran congeners.

Aryl hydrocarbon hydroxylase (AHH)-inducing potency of eight polychlorinated dibenzofuran (PCDF) isomers, 3,4,5,3',4',5'-hexachlorobiphenyl (HCB) and 2,3,7,8-tetrachlorodibenzo-p-dioxon (TCDD) in two inbred mouse strains (AHH responsive and nonresponsive mouse strains) and eight human lymphoblastoid cell lines (four males and four females) was investigated to evaluate their relative toxic potency. In AHH nonresponsive DBA mouse strain, only TCDD induced hepatic AHH activity at a dose of 30 micrograms/kg, while in AHH responsive C57 mouse strain, six PCDF isomers besides TCDD could enhance the enzyme activity significantly. 2,3,7,8-Tetrachlorodibenzofuran (2,3,7,8-TCDF), 1,2,3,7,8-pentachlorodibenzofuran (1,2,3,7,8-PCDF) and 2,3,4,7,8-pentachlorodibenzofuran (2,3,4,7,8-PCDF) showed the highest AHH inducing activity among the PCDF isomers tested. In contrast with the results obtained from the mouse experiments, in human lymphoblastoid cells, 2,3,4,7,8-PCDF, 1,2,3,4,6,7-hexachlorodibenzofuran (1,2,3,4,6,7-HCDF) and 1,2,3,7,8-hexachlorodibenzofuran (1,2,3,4,7,8-HCDF) elicited the highest AHH induction and were as potent AHH inducers as TCDD. These observations suggest that toxicities of 2,3,4,7,8-PCDF, 1,2,3,4,6,7-HCDF and 1,2,3,4,7,8-HCDF in human tissues may be comparable to that of TCDD. It was also observed that in both male and female human cell lines, the degree of AHH inducibilities of these compounds were roughly parallel to that of 3-methylcholanthrene, possibly indicating that genetic susceptibility among human population to the toxic compounds are also present similar to those reported among mouse strains.

Animals↗
PubMed1985

Health status of Japanese and Taiwanese after exposure to contaminated rice oil.

Mass poisonings, called yusho and yu-cheng, occurred in western Japan in 1968 and central Taiwan in 1979, respectively. These occurrences were separately caused by ingestion of rice oils contaminated with polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs) and polychlorinated quaterphenyls. The total intakes of PCBs and PCDFs by the patients were calculated to be, on the average, 633 and 3.4 mg for yusho, respectively, and 973 and 3.84 mg for yu-cheng, respectively, similar amounts of the causal agents being ingested in both instances. Increased eye discharge, pigmentation of nails, skin and mucous membrane, acneform eruptions and feeling of weakness were the most notable symptoms for both the poisonings. The PCB concentrations in the blood of patients were 1-30 ppb for yusho and 3-1156 ppb for yu-cheng five years and one year after the outbreaks, respectively. For the yusho patients, the clinical severity was closely related to the total amount of rice oil consumed and to the blood PCB concentration and the gas chromatographic pattern of blood PCBs.

Adipose Tissue↗
PubMed1985

[Magnetic resonance imaging of cardiovascular thrombi].

Magnetic resonance imaging (MRI) was performed for 10 patients with cardiovascular thrombi using a 0.1-Tesla resistive type apparatus (ASAHI MARK-J). In all cases thrombi were clearly imaged by NMR and their shapes closely resembled those imaged by X-ray CT. Mural thrombi located within left ventricular aneurysms of two patients with old anteroseptal myocardial infarction were semilunar in form. A mural thrombus in the right ventricle of a patient with cardiovascular Behcet's disease was also clearly imaged. Mural thrombi within the enlarged left atrium of two patients with mitral valve stenosis and insufficiency were clearly demonstrated in both cross- and longitudinal sections. In three patients with thoracic aortic aneurysm, mural thrombi were recognized within the local dilatations of the aorta. In two patients with dissecting aortic aneurysm, mural thrombi were visualized within false lumen using MRI. Mean T1 values and standard deviations for the left ventricular cavity, the left ventricular wall, and the thrombi were 639 +/- 49, 349 +/- 17 and 316 +/- 84 msec, respectively. Mean T1 values of the thrombi were usually shorter than those of the left ventricular wall. Some supposedly fresh thrombi had longer T1 values, however.

Adult↗
PubMed1985

[Magnetic resonance imaging of cardiovascular diseases: advantages of coronal and sagittal planes].

The usefulness of coronal and sagittal sections of the cardiovascular system by magnetic resonance imaging was evaluated. Coronal, sagittal and transverse spin echo scans using ECG-non-gating and gating during systole and diastole were performed for five normal volunteers, 91 with heart diseases (25 valvular disease, 28 ischemic heart disease, 14 cardiomyopathies, 14 congenital malformations, four pericardial diseases, and six others) and 32 patients with aortic abnormalities (17 aneurysms, 10 dissections and five others) using a 2.5 KGauss unit. Cardiac gating necessitated six to eight min per scan, but it was mandatory to obtain clear images of the details. On the other hand, in most of the aortic abnormalities, diagnostic images were obtained by the ECG-non-gating technique which required only about 2.5 min per scan. Coronal and sagittal sections were useful for estimating the entire shape and size of each cardiac chamber and intracardiac thrombi, the extent of postinfarctional wall thinning and cardiac aneurysms, and hypertrophy or narrowing of both the ventricular outflow tracts and apex. These planes were particularly useful, and more contributory than transverse planes for detecting inferior myocardial damage such as infarction. A few coronal and sagittal scans were sufficient to diagnose extensive lesions of the aorta, such as atherosclerosis, dissections and the aortitis syndrome. Local lesions such as coarctation, supravalvular aortic stenosis, annulo-aortic ectasia and aneurysm, especially those originating in the inferior wall of the aortic arch were easily discovered. Since the main arteries, such as the innominate, left common carotid, left subclavian and renal arteries, were clearly demonstrated by coronal images, coronal scans were considered more useful than transverse ones for observing the relationship between these arteries and dissections or aneurysms of the arch and of the abdominal aorta.

Coronary Disease↗
PubMed1985

[A case of pentalogy of Fallot with numerous collaterals evaluated by magnetic resonance imaging: a report of an adult case].

In this report, the diagnostic value of magnetic resonance imaging (MRI) was compared with that of two-dimensional echocardiography, computed tomography and cardiac catheterization in a patient with pentalogy of Fallot who survived to her fortieth year. The advantages and disadvantages of MRI in diagnosing the present case were as follows: The cardiovascular system, with the exception of atrial septal defect, was evaluated precisely. Collateral vessels were detected using MRI, but impossible with other non-invasive methods. MRI was particularly suitable for imaging the cardiovascular system because of the high contrast between the lower intensity signal of the blood and higher intensity signal of the myocardium and blood vessel walls. Using MRI, data acquisition time was 1.5 min per section. Gated MRI required more time for data acquisition. However, various oblique tomographic projections and very clear static images could be obtained using gated MRI. MRI should be one of the best diagnostic techniques for diagnosing congenital heart disease.

Adult↗
PubMed1985

[Positron computed tomography for myocardial uptake of N-13 ammonia in patients with hypertrophic cardiomyopathy: a preliminary study].

In the present study, positron computed tomography (PCT) was used to evaluate the myocardial uptake of N-13 ammonia in patients with hypertrophic cardiomyopathy (HCM). Eight subjects including two normal persons, four patients with HCM, and two with old myocardial infarction (OMI) were selected for the study. N-13 ammonia was administered intravenously as a bolus and, commencing with the tracer injection, serial 30-second PCT scans were performed. The results were summarized as follows: The first scan exhibiting cardiac blood pool images revealed a reduced left ventricular cavity in the HCM subjects. After clearance of N-13 from the cardiopulmonary vasculature, the left ventricular myocardium was clearly visualized and an increased myocardial mass with characteristic morphology was demonstrated in the HCM subjects. Detailed analysis of the time-activity curves of the blood pool and myocardium derived from these serial scan images disclosed two uptake phases in the uptake mode of N-13 ammonia. In the initial phase within three minutes, the myocardial uptake of N-13 was rapid in the normal and OMI subjects, whereas its significant delay was observed in the HCM subjects. This may reflect an abnormal initial extraction of N-13 ammonia in the HCM patients compared with the other subjects. Subsequently, in the second phase, which was characterized by a gradual increase of N-13 in the myocardium, the HCM subjects revealed higher uptake ratios than did the others. This may indicate an increased extraction of metabolites of N-13 ammonia during the second phase. These preliminary results underscore the usefulness of dynamic PCT with N-13 ammonia for the assessment of HCM.

Adult↗