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Biomedical subjects

Y Tateno

Publications and source records attributed to Y Tateno.

At least 19 recordsLinked to original sources
PubMed1992

In vivo binding of [11C]Ro15-4513 in human brain measured with PET.

Ro15-4513, an azide derivative of benzodiazepine antagonist flumazenil (Ro15-1788), and Ro15-1788 were labelled with carbon 11. Sequential PET scans following injection of [11C]Ro15-4513 or [11C]Ro15-1788 into normal male healthy volunteers were measured, and kinetic analysis using pons as a reference region was performed. [11C]Ro15-4513 was highly accumulated in frontal cortex, temporal cortex, hippocampus and relatively lower accumulation in occipital cortex, whereas almost homogeneous distribution of Ro15-1788 throughout cortex area was seen. The kinetic analysis revealed that such differences of regional distribution in brain between two labelled ligands were mainly due to the regional difference of the dissociation rate constants in vivo (k4). [11C]Ro15-4513 may be a useful tool for the in vivo study of benzodiazepine receptors in human brain.

Adult↗
PubMed1992

[Preliminary specification of X-ray CT for lung cancer screening (LSCT) and its evaluation on risk-cost-effectiveness].

In Japan mass screening for lung cancer is widely performed by chest X-ray film of 10 x 10 cm, with sputum cytology for high-risk groups. However, the effectiveness of the present mass screening program for lung cancer has been less than expected, although some date have shown improvement of the survival rate as a result of mass screening. We propose a new X-ray CT method of screening for lung cancer called Lung Cancer Screening CT (LSCT). The preliminary specifications for LSCT are as follows: scan speed is within 10 sec for a 40 cm length with a 1 cm slice thickness, and the absorption dose for lung is less than 1 cGy. A computer-assisted diagnostic system is necessary for image reading. The risk-benefit analysis of LSCT indicates that Japanese men and women over 45 years old can be screened in 1992 and thereafter. The cost per person.year of LSCT screening is estimated to be 1.4 x 10(6) yen for a population incidence rate of 50 x 10(-5) person/year and average life expectancy of 30 years. In 1992 the above condition will be satisfied by men aged 55 years old and above, but not by women of any age. We believe that LSCT should be developed further and tested in the high-risk group of men with an incidence rate of 100 x 10(-5) persons/year or more.

Adult↗
PubMed1992

[Evaluation of performance in diagnosis of pneumoconiosis using FCR (Fuji Computed Radiography)].

The purpose of this study was to determine the applicability of the FCR system to the diagnosis of pneumoconiosis. In the study, images of pneumoconiosis obtained by FCR were collected from the Rosai Hospital for Silicosis, and the distribution, shape and size of small opacities of pneumoconiosis were determined by three of the authors. An image data base was prepared, and diagnosis of pneumoconiosis using FCR test films was performed by 12 physicians with reference to reduced ILO films. Among the data obtained, data relating to profusion were analyzed. The results were compared with those obtained in the previous study. It was found that, if suitable image processing was carried on FCR test films, profusion could be classified with an accuracy equal to that of the diagnosis of pneumoconiosis with usual full-size films. It was necessary to establish standard films obtained by FCR in order to improve the accuracy of diagnosis of pneumoconiosis using FCR.

Evaluation Studies as Topic↗
PubMed1992

D1 dopamine receptor binding in mood disorders measured by positron emission tomography.

D1 dopamine receptor binding in mood disorders was studied by positron emission tomography (PET) using 11C-SCH23390. Ten patients with bipolar mood disorders and 21 normal controls were studied in the drug-free state. The patients were in euthymic (N = 6), depressed (N = 3) and manic (N = 1) states. Regional radioactivity in the brain was followed for 40 min by PET. A two-compartment model was used to obtain the binding potential (k3/k4) for the striatum and frontal cortex. The binding potentials for the frontal cortex for the patients were significantly lower than those for normal controls, whereas those for striatum were not significantly different. These findings suggest that D1 dopamine receptors in the frontal cortex may be in a different state in patients with bipolar mood disorders.

Adult↗
PubMed1992

High-energy phosphate metabolism of the myocardium in normal subjects and patients with various cardiomyopathies--the study using ECG gated MR spectroscopy with a localization technique.

Nuclear magnetic resonance spectroscopy (MRS) is a new technique for the evaluation of myocardial metabolism. Recently, localized MRS has been clinically available to measure by a non-invasive method the relative concentrations of the high-energy phosphate metabolites in the myocardium. We performed ECG gated P-31 MRS using ISIS (image-selected in vivo spectroscopy) in 15 normal volunteers, 12 patients with hypertrophic cardiomyopathy, 12 with left ventricular hypertrophy, 6 with dilated cardiomyopathy and 11 with specific heart muscle disease. Myocardial peak height ratios of PCr/gamma-ATP, Pi/gamma-ATP and PCr/Pi were measured. Myocardial P-31 MRS demonstrated a significant decrease in the ratio PCr/ATP in patients with hypertrophic cardiomyopathy and specific heart muscle disease as compared with normal subjects, indicating myocardial metabolic disturbance in these patients. The ratio of PCr/ATP in patients with dilated cardiomyopathy did not differ significantly from that of normal subjects. However, exercise MRS revealed a marked decrease of PCr peak in an asymptomatic patient with dilated cardiomyopathy, which may indicate a latent metabolic disturbance in the myocardium of dilated cardiomyopathy.

Adenosine Triphosphate↗
PubMed1992

[Intramuscular degeneration process in Duchenne muscular dystrophy--investigation by longitudinal MR imaging of the skeletal muscles].

Intramuscular degeneration process of Duchenne dystrophy skeletal muscles was investigated by longitudinal skeletal muscle imaging with high-field-strength NMR-CT of 1.5 Tesla. Thigh muscles in 10 cases ranging in age from 4 to 19 years were examined by T1-weighed longitudinal images (TR = 215-505 ms, TE = 19-20 ms). Following results were obtained: (1) Skeletal muscle degeneration was depicted as high signal intensity area reflecting its high fat contents. (2) These high signal intensity areas had a longitudinally streaky appearance in parallel direction with myofibers. (3) These findings were more prominent toward myotendon junction than muscle bellies. (4) Skeletal muscle degeneration progressed rapidly between 7 to 10 years of age, and reached a plateau after that.

Adult↗
PubMed1991

Robustness of maximum likelihood tree estimation against different patterns of base substitutions.

In the maximum likelihood (ML) method for estimating a molecular phylogenetic tree, the pattern of nucleotide substitutions for computing likelihood values is assumed to be simpler than that of the actual evolutionary process, simply because the process, considered to be quite devious, is unknown. The problem, however, is that there has been no guarantee to endorse the simplification. To study this problem, we first evaluated the robustness of the ML method in the estimation of molecular trees against different nucleotide substitution patterns, including Jukes and Cantor's, the simplest ever proposed. Namely, we conducted computer simulations in which we could set up various evolutionary models of a hypothetical gene, and define a true tree to which an estimated tree by the ML method was to be compared. The results show that topology estimation by the ML method is considerably robust against different ratios of transitions to transversions and different GC contents, but branch length estimation is not so. The ML tree estimation based on Jukes and Cantor's model is also revealed to be resistant to GC content, but rather sensitive to the ratio of transitions to transversions. We then applied the ML method with different substitution patterns to nucleotide sequence data on tax gene from T-cell leukemia viruses whose evolutionary process must have been more complicated than that of the hypothetical gene. The results are in accordance with those from the simulation study, showing that Jukes and Cantor's model is as useful as a more complicated one for making inferences about molecular phylogeny of the viruses.

Base Composition↗
PubMed1991

Age-related changes in human D1 dopamine receptors measured by positron emission tomography.

The effects of age on the binding parameters of 11C-SCH23390, the highly selective ligand for central D1 dopamine receptors, at specific binding sites in the brain were studied. Seventeen healthy male volunteers (20-72 years old) participated. Regional radioactivity in the brain was followed for 40 min by positron emission tomography (PET). A high accumulation of radioactivity was observed in the striatum and there was a conspicuous accumulation in the neocortex. A two-compartment model was used to obtain quantitative estimates of rate constants of association (K3) and dissociation (k4). The binding potential (k3/k4) of the dopamine D1 receptors in the striatum and frontal cortex decreased by 35% and 39%, respectively, with age. The value of k3 decreased by 58% in the striatum and 83% in the frontal cortex, whereas the value of k4 decreased by 35% in the striatum and 72% in the frontal cortex with age.

Adult↗
PubMed1991

Quantitative measurement of uptake of radiolabeled monoclonal antibody by means of planar data.

Data obtained from planar images were used to measure the uptake of monoclonal antibody in organs and tumors. Background counts included in the region of interest were eliminated, and the attenuation of the photons emitted by the radionuclide through the intervening tissues was compensated for. The background counts and the intensity of the attenuation were determined from the results of phantom studies and numerical integration with a personal computer. The quantitative uptake of 111In labeled anti-melanoma Monoclonal Antibody (ZME-018) in a melanoma lesion, the liver, and the bone marrow of a patient was measured by the planar method which we developed.

Antibodies, Monoclonal↗
PubMed1991

Quantitative in vivo analysis of benzodiazepine binding sites in the human brain using positron emission tomography.

Central-type benzodiazepine binding sites were characterized in a single normal human subject, using positron emission tomography (PET) and the radiolabelled benzodiazepine antagonist, carbon-11 labelled flumazenil ([11C] Ro 15-1788). The subject was scanned using tracer alone and tracer plus 4 different concentrations of unlabelled Ro 15-1788, including one concentration of unlabelled Ro 15-1788, chosen to produce maximum displacement of [11C] Ro 15-1788 from specific binding sites. Concentrations of free, unmetabolized [11C] Ro 15-1788 in plasma were estimated using a simple extraction and ultrafiltration method. Radioactivity in the regional exchangeable pool in brain was estimated under non-saturation conditions from the ratio of radioactivity in brain to plasma, under saturation conditions and the kinetics of free ligand in plasma. The specific binding was, then, estimated by the difference between the total radioactivity in brain and exchangeable pool radioactivity. Scatchard analyses were performed to yield Bmax and Kd values under pseudo-equilibrium conditions, which was observed as an increase of specific binding/free with reduction in specific binding. In cerebral cortex and cerebellum, the Bmax values were about 62-73 nmol/l and the Kd values were 3.6-6 nM in the estimation of free ligand in plasma and 12-15 nM in the estimation of exchangeable pool in brain, as free in brain.

Adult↗
PubMed1991

Comparison of complete amino acid sequences and receptor-binding properties among 13 serotypes of hemagglutinins of influenza A viruses.

We determined the sequences of 7 serotypes (H4, H6, H8, H9, H11, H12, and H13) of hemagglutinin (HA) genes, which have not been reported so far. The coding regions consisted of 1692 nucleotides in H4, 1698 in H6, 1695 in H8, 1680 in H9, 1695 in H11, 1692 in H12, and 1698 in H13, and specified 564, 566, 565, 560, 565, 564, and 566 amino acids, respectively. By comparison of amino acid sequences, 13 HA serotypes could be divided into two families, i.e., an H1 group (H1, H2, H5, H6, H8, H9, H11, H12, and H13) and an H3 group (H3, H4, H7, and H10). The relationship was essentially similar to that reported by Air from the comparison of 80 amino-terminal amino acid sequence of 12 HA serotypes (G.M. Air, 1981, Proc. Natl. Acad. Sci. USA 78, 7639-7643). Though a considerable amino acid sequence difference exists between certain HA serotypes, several amino acid residues in fusion peptides (HA2(1-11)) and receptor-binding sites (HA1(98), -134, -138, -153, -183, and -195) were shown to be conserved among the 13 HA serotypes. Human H1 and avian H3, H4, H8, and H10 viruses preferentially bound NeuAc alpha 2,3Gal sequences, whereas human H2 and H3 and avian H6 and H9 viruses bound NeuAc alpha 2,6Gal sequences, although the amino acid residues at position 226 of human H2 and avian H6 and H9 serotype HAs are glutamine. These results show that the amino acid residue at position 226 is not necessarily a determinant of receptor specificity for all serotypes.

Amino Acid Sequence↗
PubMed1991

Lesion of the nucleus basalis magnocellularis does not affect cerebral cortical blood flow in rats.

The effects of a unilateral ibotenic acid lesion of the nucleus basalis magnocellularis (NBM) on blood flow of the cerebral cortex and striatum were studied at 2, 4, 8 and 16 weeks after the lesion in conscious rats. In the cerebral cortex, no side-to-side difference in blood flow was observed, though cholinergic enzyme activity was markedly reduced on the side of the lesion. The results suggest that NBM lesion produces disturbance of cholinergic neurons in the cerebral cortex without significant alteration of blood flow.

Acetylcholinesterase↗
PubMed1991

Study of biodistribution of enflurane in rats with in vivo 19F MRI.

In vivo 19F magnetic resonance imaging (MRI) of anesthetized rats enabled us to visualize the biodistribution of fluorinated anesthetics and to document the changes in MR signals in the body during the induction and the elimination phase of anesthesia. The authors examined in vivo 19F MRI in rats anesthetized with concentrations of 1.75-2.0% enflurane and demonstrated its in vivo distribution with concomitant 1H and 13C MRI to verify the anatomical correlation. Distinct 19F MR signals were acquired predominantly from the systemic adipose tissue and the liver. Additionally, the temporal changes in the tissue during and after anesthesia were characterized with in vivo 19F MRI in 6.4 min of the acquisition time. The 19F MR signals increased with time after anesthesia; however, the signals from the adipose tissue were apparently stronger than those from the liver. Following the discontinuation of inhalation, the MR signals in the liver decreased far more rapidly than those from the adipose tissue. When the animal woke up and began to move, the MR signals were still visible in the adipose tissue. These results confirmed the fact that enflurane dissolves preferentially in the adipose tissue and remains when the anesthetic effect disappears. Additionally, 19F MR signals of the liver during the elimination phase might reflect the concentration of enflurane in the blood.

Abdomen↗
PubMed1991

[The group study of diagnostic efficacy of cerebro-vascular disease by I-123 IMP SPECT images obtained with ring type SPECT scanner--the ROC analysis on the diagnosis of perfusion defect and redistribution].

We performed two image reading experiments in order to investigate the diagnostic capability of I-123 IMP SPECT obtained by the ring type SPECT scanner in cerebro-vascular disease. Fourteen physicians diagnosed SPECT images of 55 cases with reference to clinical neurological informations, first without brain XCT images and second with XCT images. Each physician detected perfusion defects and redistributions of I-123 IMP and assigned a confidence level of abnormality for these SPECT findings by means of five rating method. From results obtained by ROC analysis, we concluded as follows: (1) Generally, I-123 IMP SPECT is a stable diagnostic modality in the diagnosis of cerebro-vascular disease and the image reading of XCT had no effects on the diagnosis of SPECT on the whole of physician, (2) However, there were unnegligible differences among individuals in the detectability of findings and the effect of XCT image reading, (3) Detectability of redistribution of I-123 IMP was lower than that of perfusion defect and inter-observer variation in the diagnostic performance for redistribution was larger than that of perfusion defect. The results suggest that it is necessary to standardize diagnostic criteria among physicians for redistribution of I-123 IMP.

Amphetamines↗
PubMed1991

In vivo sodium-23 MRI in brain tumors: evaluation of preliminary clinical experience.

In vivo sodium-23 magnetic resonance (MR) imaging in the head was performed in ten normal volunteers and six patients with brain tumors on a commercially available 1.5 Tesla whole-body MR system. Although sodium MR signal from the brain parenchyma could hardly be detected on routine spin echo (SE) pulse sequence, free induction decay (FID) image with echo time of 1.9 msec demonstrated MR signal in the normal brain tissue. On the other hand, extracellular sodium of cerebrospinal fluid, large venous sinus, and vitreous humor offered high sodium MR signal intensity due to the quantity of sodium and the relatively longer transverse relaxation time (50-60 msec) compared to that of intracellular sodium (less than a few msec). Strong signal was obtained in gliomas with superior contrast, though the delineation of the tumor tissue from edema was as difficult as when seen on proton T2 weighted SE image. Meningioma itself gave much less of a sodium MR signal compared to glioma. Peritumoral edema associated with meningioma showed a markedly high sodium MR signal which was more prominent adjacent to the tumor, although proton SE image revealed the peritumoral edema as homogeneous. Pathological tissues such as brain tumors and edema could be readily depicted as significantly high sodium-23 MR signal, apparently different from normal brain tissues. The current status of in vivo sodium MR imaging is discussed. The authors concluded that early clinical experience of in vivo sodium-23 MR imaging brought promising results in the evaluation of brain tumors and edema; otherwise, discrimination and quantification of multiple T2 components and the improvement of spatial resolution are desperately needed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗