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Biomedical subjects

Y Tateno

Publications and source records attributed to Y Tateno.

At least 55 records · Page 3Linked to original sources
PubMed1994

[The effect of CD8+ cells on isolation and replication of HIV-1].

Human immunodeficiency virus type 1 (HIV-1) seropositive individuals are known to have a population of CD8+T lymphocytes which can suppress the replication of the virus. Two hundred and twelve peripheral blood mononuclear cells (PBMC) samples obtained from 42 seropositive individuals were examined for HIV-1 isolation. HIV-1 recovery rate reached almost 90% by coculture of CD8+ cell-depleted PBMC with uninfected normal PBMC. These results indicated the usefulness of panning method of CD8+ cell for isolation of HIV-1 from asymptomatic carriers (AC). To investigate the suppressive effect of CD8+ cells on HIV-1 replication, we characterized HIV-1 isolates from the same blood samples obtained from five AC individuals before and after the removal of CD8+ cells. Comparative studies of paired isolates revealed significant differences in their replication kinetics in the presence of autologous or allogeneic CD8+ cells. The paired isolates from four out of 5 AC individuals revealed significant differences in their genetic structures, although their biological properties, such as replication rate of cell tropism, were almost the same between the paired isolates. One exception, that of paired isolates from one AC with clinical data of near AIDS-related complex showed a similar genetic structure and similar biological properties. Thus, we showed that many AC individuals during the early clinical stages simultaneously carried two or more replication-competent HIV-ls in vivo which have different genomic backgrounds and sensitivity to the antiviral effects of CD8+ cells.

Base Sequence↗
PubMed1993

No age-related changes in human benzodiazepine receptor binding measured by PET with [11C]Ro 15-4513.

The effects of age on the binding of [11C]Ro 15-4513, a partial inverse agonist of the central benzodiazepine receptor, were studied. Sixteen healthy male volunteers (21-78 years old) participated. Regional radioactivity in the brain was followed for 45 min by positron emission tomography after a bolus injection of [11C]Ro 15-4513. Similar tracer kinetics were observed in both young and old subjects. For the quantification of receptor binding in vivo, a compartment model, in which radioactivity in the pons was used as an input function, was applied. There were no significant changes in the binding potentials with age (P > 0.1) in ten brain regions. These observations delineate an interesting difference between central benzodiazepine (BZ) receptors and other neurotransmitter receptors in the human brain measured by PET that have been shown to have a reduction with age.

Adult↗
PubMed1993

Evolution of the glutamine synthetase gene, one of the oldest existing and functioning genes.

We performed molecular phylogenetic analyses of glutamine synthetase (GS) genes in order to investigate their evolutionary history. The analyses were done on 30 DNA sequences of the GS gene which included both prokaryotes and eukaryotes. Two types of GS genes are known at present: the GSI gene found so far only in prokaryotes and the GSII gene found in both prokaryotes and eukaryotes. Our study has shown that the two types of GS gene were produced by a gene duplication which preceded, perhaps by > 1000 million years, the divergence of eukaryotes and prokaryotes. The results are consistent with the facts that (i) GS is a key enzyme of nitrogen metabolism found in all extant life forms and (ii) the oldest biological fossils date back 3800 million years. Thus, we suggest that GS genes are one of the oldest existing and functioning genes in the history of gene evolution and that GSI genes should also exist in eukaryotes. Furthermore, our study may stimulate investigation on the evolution of "preprokaryotes," by which we mean the organisms that existed during the era between the origin of life and the divergence of prokaryotes and eukaryotes.

Animals↗
PubMed1993

[Estimation of risk due to radiation exposure in the mass screening of cancer in Japan].

Five types of mass screening programs for cancer are performed under the auspices of the Adult Health Promoting Act of the Japanese Government. The cancers involved are those of stomach, uterus, lung, breast and colon. Radiological images are routinely used for the screening of stomach and lung cancers, and mammography will be employed in the near future. In this study, the risk due to radiation exposure in the above-mentioned screening programs was estimated for an individual who participates in the screening of each cancer annually. The dose absorbed at each screening was estimated and an additive risk model was used as the pattern of occurrence of radiation-induced cancers for simplicity. Safety was also estimated. Results showed that the risk of a shortened life-expectancy as a result of undergoing annual mass screening for breast, stomach and lung cancer was insignificant in comparison with the average life-expectancy of about 80 years for Japanese men and women, and much smaller than the benefit of mass screening expressed in terms of prolonged life-expectancy. However, it should be emphasized that a quality control program must be established to keep the dose absorbed at each X-ray screening examination as low as reasonably possible.

Female↗
PubMed1993

Age-related changes in human muscarinic acetylcholine receptors measured by positron emission tomography.

The effects of age on the binding parameters of [11C]N- methyl-4-piperidylbenzilate ([11C]NMPB), a specific muscarinic cholinergic receptor ligand, were studied. Eighteen healthy male volunteers (18-75 years old) participated. Regional radioactivity in the brain was followed for 60 min by positron emission tomography (PET). Uptake of [11C]NMPB continuously increased in all brain areas with the exception of the cerebellum. For the quantification of receptor binding, a compartment model, in which radioactivity in the cerebellum was used as an input function, was used. The binding parameter, K3, of muscarinic acetylcholine receptors in eight brain regions (pons, hippocampus, frontal cortex, striatum, temporal cortex, thalamus, occipital cortex, parietal cortex) showed an age-related decrease of about 45% over the age range.

Adolescent↗
PubMed1993

Dopamine D2 and serotonin S2 receptors in susceptibility to methamphetamine psychosis detected by positron emission tomography.

Positron emission tomography (PET) was used to assess the role of dopamine D2 receptors in the striatum and serotonin S2 receptors in the frontal cortex in the susceptibility to methamphetamine-induced psychosis. Subjects were six men who had previously experienced methamphetamine psychosis (methamphetamine subjects) and 10 age- and sex-matched control subjects. The radiotracer used was 11C-N-methylspiperone. Although binding availability, assessed by dynamic analysis, in the two regions did not differ between the two groups, the ratio of binding availability in the striatum to that in the frontal cortex significantly decreased in the methamphetamine subjects as compared with the control subjects. These findings suggest that an imbalance in the activity of these two receptors may be related to the susceptibility to methamphetamine psychosis.

Adult↗
PubMed1993

A new gel using super absorbent polymer for mapping the spatial dose distributions of electron beams by MR imager.

A technique for mapping the spatial dose distribution with a magnetic resonance imager is presented. A ferrous sulphate solution with sulfuric acid was used as the detecting medium for radiation dose. To make a gel of the solution for filling up a cubic phantom, we developed a new gel component that is combined with a super absorbent polymer (Sumikagel N-100) and a cross-linked dextran gel (Sephadex G-200). In order to make the application for radiation treatment planning, mapping of the dose distribution was carried out using a Unix computer.

Electrons↗
PubMed1993

Dopamine D1 receptors in Parkinson's disease and striatonigral degeneration: a positron emission tomography study.

Striatal dopamine D1 receptors were investigated in 11 patients with Parkinson's disease (PD), five patients with striatonigral degeneration (SND) and six age-matched controls by positron emission tomography and carbon-11 labelled SCH23390. The SND patients showed mean 12%, 21%, and 31% declines in the ratios of radioactivity in the caudate, anterior putamen, and posterior putamen compared with that in the occipital cortex. These ratios were not significantly altered in the PD patients. The results may explain the different therapeutic responses to levadopa between SND and PD patients, and this technique might prove useful for their differentiation.

Adult↗
PubMed1993

[Evaluation of blood flow in aortic aneurysm and dissection by cine magnetic resonance imaging].

The blood flow in aortic aneurysms and dissections was evaluated using cine MR imaging which depicts turbulent blood flow as a signal loss within a high-intensity blood pool or flowing blood. Six patients with 8 aortic aneurysms ranging 38 to 70 mm in diameter, and 16 patients with aortic dissections were imaged with a 0.5 or 1.5 T superconducting magnet using an ECG-gated fast field echo technique. Circulating flows were observed in 3 of 8 aortic aneurysms. This suggests that turbulent blood flow did not occur prominently in the relatively small aortic aneurysms imaged in this study. The false lumens were thrombosed in 2 of 16 aortic dissections. In 13 of the remaining 14 dissections jet flows were observed through the entry into the false lumen. In 2 of these cases the jet flows moved to and fro through the entry. The entry was not detected in a small abdominal aortic dissection. Re-entry was seen in one case. Using a spin-echo imaging technique, the entry can be diagnosed by detecting the interruption of the intimal flap and the flow void within the false lumen. However, the entry was more clearly depicted and the direction of blood flow better determined by cine MR imaging compared with the conventional spin-echo imaging technique. Cine MR imaging provides useful information about the blood flow in aortic aneurysms and dissections noninvasively.

Aged↗
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↗