Biomedical subjects
Publications and source records attributed to T Maeda.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The question of the nasotemporal overlap of ganglion cells in the central retina, which project to the ipsilateral and contralateral lateral geniculate nucleus, was reexamined in the cat by means of a retrograde fluorescent double-labeling technique. The horizontal separation between the ipsilateral and contralateral decussation lines, which corresponded to the width of the median strip of overlap, was approximately 0.2 mm. This is the first direct confirmation of the extent of such overlap in the cat retinal ganglion cells, which had been previously studied by indirect methods.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
In order to investigate an influence of advancing age on regional cerebral blood [flow](rCBF), 125 measurements of rCBF were made by 133Xe inhalation method in 90 normal subjects without cerebral symptoms and risk factors of atherothrombotic stroke including hypertension, diabetes mellitus, and hyperlipidemia. There were 46 male and 44 female aged 19 to 80 years old (mean 42.5). The measurements were carried out in a quiet, semi-darkened room with the subjects at rest and eye closed. 133Xe inhalation system (Meditronic-Novo Diagnostic Systems, Inhalation Cerebrograph, Denmark) consists of 32 scintillation detectors, the lateral part of each hemisphere being covered by 16 detectors placed in parallel. One pair of the detectors is mounted in place over the brain stem and cerebellar region. Relationship of age and rCBF computed as the initial slope index (ISI) by Fourier analysis was investigated with both correlation and regression analyses, and age-matched normal values were calculated. End-tidal partial pressure for carbon dioxide (PECO2) was recorded from the face mask during the measurements along with the mean arterial blood pressure (MABP). ISI values were not corrected for changes in PECO2. PECO2 and MABP did not differ significantly among the normal subjects. There were no significant differences in the hemispheric mean ISI values between the right and left hemispheres. Mean brain ISI values showed significant negative correlation with advancing age (r = -0.67, p less than 0.001), and regression line was Y = -0.30X + 67.8. Ninety five per-cent confidence interval of the regression line was +/- 11.8. Regional ISI values also showed significant negative correlations with advancing age in the whole brain (p less than 0.001). There were no significant differences in the correlation coefficients obtained from parallel regions between the right and left hemispheres. The regional reduction of ISI values with advancing age was significantly greater in the regional distribution of the middle cerebral arteries bilaterally, compared with regions in the distribution of either the anterior cerebral, the posterior cerebral, or vertebrobasilar arteries (p less than 0.05). Regional hemispheric percent value of frontal lobe was greater than that of either parietal, temporal, occipital lobe, or brain stem and cerebellar region in the whole age. But, this hyperfrontal distribution became gradually obscured with advancing age, because reduction of ISI values with aging was significantly greater in the frontal than in other regions. It is concluded that measured rCBF of a patient have to be compared with age-matched normal values of mean brain and each region. Judgment image was produced with dividing patient value by 95% confidence limit of age-matched normal value. According to this image, regions in which rCBF significantly decrease or increase can be easily evaluated.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
To assess intramyocardial blood flow distribution by the contrast echocardiographic technique, we studied the effect of intracoronary injections of contrast agents on the echo intensity of the myocardium. As fundamental experiments, we made injections of ICG, urografin, artificial blood (FC-43) and microsphere into the coronary artery in open chest dogs and observed the changes in echo density of the myocardium. Bolus injection of 10 ml ICG into the coronary artery produced little change in the myocardial echo intensity, but bolus injection of 10 ml urografin, FC-43 and microsphere into the left circumflex coronary artery (LCX) and left anterior descending coronary artery (LAD) immediately increased the echo intensity of the left ventricular posterior wall (LVPW) and interventricular septum (IVS), respectively. Enhanced echo areas correlated well with the regions perfused by LCX and LAD, respectively. Clinically, we recorded two-dimensional echocardiograms during coronary arteriography (CAG) in 10 patients. In six of the 10 patients, the echo intensity of IVS increased during left CAG and in four of eight patients the echo intensity of LVPW increased during right CAG. Contrast echomyocardiography, contrast enhanced echocardiography of the myocardium, proved a useful technique for the evaluation of intramyocardial blood flow.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Benzyloxycarbonylalanine chloromethyl ketone (Z-Ala-CH2Cl) was found to inhibit the processing of the prolipoprotein, a secretory precursor of the lipoprotein of the Escherichia coli outer membrane. The accumulation of the prolipoprotein in the presence of Z-Ala-CH2Cl was observed both in vivo and in vitro. Z-Ala-CH2Cl did not inhibit the processing of precursors of the other major outer membrane proteins. A preliminary experiment to identify the processing enzyme(s) of the prolipoprotein was carried out with use of Z-[3H]Ala-CH2Cl and revealed that two cytoplasmic membrane proteins with Mr = 78,000 and 46,000 were predominantly labeled.
A gas chromatographic method has been developed that permits the accurate and specific determination of the hypoglycaemic agent gliclazide in plasma. Gliclazide is extracted with chloroform and, after clean-up, derivatized with diazomethane followed by heptafluorobutyric anhydride to form N-methyl-N'-heptafluorobutyrylgliclazide, which is assayed on a gas chromatograph equipped with a flame ionization detector, an electron-capture detector or a nitrogen-phosphorus sensitive detector. Accurate determinations are possible with flame ionization detection over a concentration range of 1--15 microgram/ml of gliclazide in plasma with a relative standard deviation of 5.2%. The minimum detectable concentration with electron-capture detection is 0.02 microgram per sample. Plasma levels of gliclazide in dogs following single oral administration (40 mg per dog) have also been determined.
Divergent projections of catecholamine (CA) neurons of the locus coeruleus have been studied by fluorescent retrograde double labeling in conjunction with monoamine histofluorescence technique. The present results indicate that the coerulo-cortical CA system is composed of two types of neurons. A predominant type possesses few divergent axons innervating a restricted region, while the other type projects widely to various areas of the cerebral cortex. The existence of divergent axonal projections of single CA neurons in the locus coeruleus to the cerebellum and the spinal cord, to the frontal cortex and the cerebellum, is also demonstrated.
Accumulation of 99mTc-methylene diphosphonate was observed in liver metastasis resulting from stomach carcinoma. This accumulation was located around the lesion on an emission-computed tomogram. This has not been previously reported.
The molecular mechanism of hemolysis and fusion by influenza virus in acidic media was studied. First, the effect of trypsin treatment on the activity of fibroblast-grown influenza virus was studied. The results showed that the split form of viral hemagglutinin, HA1 and HA2, but not the precursor, is responsible for the activity. Second, the interaction of egg-grown influenza virus, which contains the split hemagglutinin, with lipid liposomes was studied by spin labeling and electron microscopy. Phospholipid transfer from the viral envelope to the lipid bilayer membrane occurred within 30 s at pH 4.5-5.4. The transfer is largely independent of the lipid composition and the crystalline vs. liquid/crystalline state of the membrane. Virus-induced lysis of liposomes also took place rapidly in the same pH range. Envelope fusion with liposomes occurred at pH 5.2 but not at pH 7.0. These characteristic interactions were similar to those between influenza virus and erythrocytes reported previously. On the other hand, hemagglutinating virus of Japan did not interact with liposomes at neutral pH. These results suggest that protonation of the NH2-terminal segment of the HA2 form causes interaction of the segment with the lipid core of the target cell membrane, leading to hemolysis and fusion.
It has been reported that the tentorial confluence sign and/or hockey stick pattern on static imaging are useful in evaluating posterior cerebral artery (PCA) infarctions. In 16 cases with PCA infarction, the tentorial confluence sign was found in all cases, but a hockey stick pattern was seen in only half of these patients. The abnormal accumulations may be classified into three types. These three types seem to be consistent with the territory of the blood supply from the cortical, temporal, and/or occipital branches of the posterior cerebral artery. Emission computed tomography images may also demonstrate this consistency.
Twenty patients with ischemic heart disease were studied with biplane contrast left ventriculography and gated bloob pool scans. An ejection fraction (EF) image was calculated from each gated blood pool scan. The EF image and contrast ventriculograms were divided into three regions and seven segments respectively. The sites of asynergy observed in each study were compared. Segments two, three and six of the contrast ventriculogram corresponded to the anteroseptal and inferoapical regions of the EF image, but it was difficult to differentiate between these segments on the EF image. Segments three and four corresponded to the inferoapical region and segments five and seven corresponded to the posterolateral region. Diffuse asynergy with a low EF (less than 30%) causes a large defect on the EF image. The mean regional EF obtained from the EF image correlated well with the EF calculated from the left ventricular volume curve (n = 50, r = 0.94).