Search PubMed⌕ Search

Biomedical subjects

Takashi Asada

Publications and source records attributed to Takashi Asada.

At least 73 records · Page 4Linked to original sources
PubMed2004

[A psychopathological study on three-dimensional computer graphics (3DCGs): special reference to pictures made by a schizophrenic patient before and after the onset].

A patient with catatonic type schizophrenia drawing 3-dimensional computer graphics (3DCGs) before and after the onset is reported. His 3DCGs are discussed from the view of psychopathology. A 21-year-old male was admitted to our hospital. He was an art student. For three months before admission, he had been absorbed in drawing 3DCGs. When he was asked to draw handmade pictures by his teacher, he experienced a bizarre mood and took an overdose of aspirin. At the time of admission, he was in a stupor state, and was diagnosed with catatonic type schizophrenia. After admission, he exhibited excitement and disorganized speech. These symptoms disappeared after administration of neuroleptics, and he was discharged. The 3DCGs he drew before and after the onset revealed several special characteristics. First, the compositions of his pictures were too geometric and too precise. Secondly, the themes of his pictures changed from romantic before the onset to symbolic after it, and the styles changed from realistic to abstractive after the onset. Finally, histograms of the 3DCGs revealed many colors before onset, which converged to simple colors after. Therefore, it was suggested that the latent pathological process at the beginning of schizophrenia might be reflected in his 3DCGs. 3DCGs are a new type of fine art. They can express beautiful and cool images more simply than handmade pictures. Due to these features, artists can create images of their innerworld, with less effort and talent than picture drawings, by computer assistance. This case suggests that the geometric working space, change-free viewpoints, and computer assistance, which are characteristics of the methods in making 3DCGs may be suitable for schizophrenic artists to create images of their innerworld. However, being absorbed in making 3DCGs could also promote the latent schizophrenic process to the onset.

Adult↗
PubMed2003

Lack of association between TrkA single nucleotide polymorphisms and sporadic Alzheimer's disease in a Japanese population.

Nerve growth factor and its receptor with tyrosine kinase activity (TrkA) have been implicated in the development of Alzheimer's disease (AD). Entire coding regions of TrkA gene harboring exons 1 through 17 were sequenced in 114 patients with sporadic AD and 112 control subjects in a Japanese population, and six known and two novel single nucleotide polymorphisms were identified, but no mutation associated with sporadic AD was identified. Concurrently, case-control analysis of TrkA gene A1674G polymorphism in 534 patients with sporadic AD and 454 control subjects has revealed no significant differences in TrkA genotype or allele frequencies even after stratification for Apolipoprotein E epsilon4 carrier statuses. Thus, the TrkA genotype does not appear to influence the risk of developing sporadic AD in a Japanese population.

Age of Onset↗
PubMed2003

Alterations of heterogeneous nuclear RNP A2 and B1 in the hippocampus of the rat after perforant pathway lesion.

We examined alterations in post-transcriptional regulation following deafferentation of the perforant pathway by focusing on heterogeneous nuclear ribonucleoprotein (hnRNP) A2 and B1 in rat hippocampi subjected to perforant pathway lesions. In control brains, immunoreactivity to both was observed in the nuclei of neurons throughout the hippocampus using immunohistochemical techniques. From 1 to 14 days post-lesion, a slight increase in A2 immunoreactivity was observed in neurons within the dentate granular layer as well in the pyramidal cells of the cornus Ammon fields ipsilateral to the lesion. In contrast, we observed a marked decrease in B1 immunoreactivity in the same regions at 1, 3 and 7 days post-lesion. All these alterations, however, were transient. A2 immunoreactivity returned to normal levels by 30 days post-lesion, and B1 immunoreactivity had completely recovered by 14 days post-lesion. The results of immunoblot analysis for A2 and B1 were wholly consistent with immunohistochemical observations. Our study suggests that post-transcriptional regulation in the hippocampal neurons changes after a perforant pathway lesion. Our study further suggests that the functions of hnRNPA2 and B1 are different, as each was differentially involved in the plastic response to deafferentation of the perforant pathway.

Acetylesterase↗
PubMed2003

Log-linear models for assessing gene-age interaction and their application to case-control studies of the apolipoprotein E (apoE) gene in Alzheimer's disease.

Case-control studies provide a powerful approach for detecting disease-susceptibility genes or assessing gene-environment interactions. We investigated the situation in which the gene being studied plays a role in several diseases, and the allele frequency among subjects free of the disease of interest consequently decreases with age as subjects die from other diseases. The logistic model is one approach frequently used for analyzing case-control data, but it cannot accommodate this dependence of genotype and age. Using a log-linear model, we therefore proposed a hierarchical procedure that could be used as a valid method for assessing interactions in such situations. We then applied this procedure to observed data on Alzheimer's disease and the apolipoprotein E gene in Japan. We were able to derive an appropriate inference on whether the interaction was a gene-age interaction or merely a bias due to death from other diseases.

Age Factors↗
PubMed2003

A case of delusional disorder, somatic type with remarkable improvement of clinical symptoms and single photon emission computed tomograpy findings following modified electroconvulsive therapy.

A 72-year-old male with delusional disorder, somatic type (DDST), was treated by modified electroconvulsive therapy (mECT). His somatic delusions were completely resolved by mECT. In parallel with the improvement of his clinical symptoms, we observed an improvement of regional cerebral blood flow (rCBF) in the left temporal and parietal lobes shown by the single photon emission computed tomograpy (SPECT). This study appears to support the utility of mECT for somatic delusions in elderly patients and suggests possible association of the dysfunction in the left temporal and parietal lobes with manifestation of the somatic delusion of the patient.

Aged↗
PubMed2003

Apolipoprotein E genotype and early Alzheimer's disease: a longitudinal SPECT study.

BACKGROUND AND PURPOSE: To determine the association of the apolipoprotein E (APOE) genotype and longitudinal changes of regional cerebral blood flow (rCBF) in Alzheimer's disease (AD). Previous reports have yielded conflicting results concerning this association. METHODS: A retrospective cohort study was performed. rCBF was noninvasively measured using 99mTc-ethyl cysteinate dimer single-photon emission computed tomography in 23 patients with probable AD at the very early stage and at a mean interval of 24 months, as well as in 55 age-matched healthy volunteers. Patients were classified into 2 groups according to the presence of the epsilon 4 allele: 11 epsilon 4 carriers and 12 noncarriers. Correction for partial volume effects (PVEs) was performed in all patients using gray matter volume measured by magnetic resonance imaging. Statistical parametric mapping was used for the analysis of absolute rCBF data and the adjusted rCBF images of relative flow distribution. RESULTS: In the baseline study, both carriers and noncarriers showed significant decreases of absolute and adjusted rCBF in the psoterior cingulate gyri and precunei. After PVE correction, carriers showed a greater spread of areas with significant rCBF reduction from the parietotemporal to the frontal area than noncarriers during the follow-up period compared to healthy volunteers. Moreover, carriers showed a significant decline of absolute rCBF in the frontal cortex from the baseline to the follow-up study. CONCLUSIONS: The authors' study suggests that the APOE epsilon 4 allele is associated with the faster progression of AD, and PVE correction may be necessary for accurate assessments of SPECT studies of AD.

Aged↗
PubMed2003

Correction for partial-volume effects on brain perfusion SPECT in healthy men.

UNLABELLED: The limited spatial resolution of SPECT scanners does not allow an exact measurement of the local radiotracer concentration in brain tissue because partial-volume effects (PVEs) underestimate concentration in small structures of the brain. The aim of this study was to determine which brain structures show greater influence of PVEs in SPECT studies on healthy volunteers and to investigate aging effects on SPECT after the PVE correction. METHODS: Brain perfusion SPECT using (99m)Tc-ethylcysteinate dimer was performed in 52 healthy men, 18-86 y old. The regional cerebral blood flow (rCBF) was noninvasively measured using graphical analysis. SPECT images were corrected for PVEs using gray-matter volume, which was segmented from coregistered MR images and convoluted with spatial resolution of SPECT scanners. Absolute rCBF data were measured using a 3-dimensional (3D) stereotactic template for regions of interest on anatomically standardized SPECT. We examined correlation of advancing age with rCBF before and after the PVE correction. To validate the correction method for PVEs, a Hoffman 3D brain phantom experiment was also performed. RESULTS: The PVE correction remarkably reduced the coefficient of variation for SPECT counts in the whole phantom. The PVE correction made the rCBF distribution more homogeneous throughout the brain with less intersubject variation than the original distribution. There were significant negative correlations between age and adjusted rCBF in the bilateral perisylvian and medial frontal areas. These correlations remained significant after the PVE correction. Instead of a positive correlation in the medial temporal structures between age and adjusted rCBF before the PVE correction, the sensorimotor and parietal areas mainly showed positive correlations after the correction. CONCLUSION: SPECT data reflect both brain volume loss and functional changes. Use of the PVE correction in brain perfusion SPECT provides a more accurate determination of rCBF even in healthy volunteers.

Adolescent↗
PubMed2003

[Dementia].

Explore the source record for details and available documents.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2002

Repeated cocaine administration differentially affects NMDA receptor subunit (NR1, NR2A-C) mRNAs in rat brain.

We investigated the effects of intermittent intraperitoneal (i.p.) injections of cocaine (20 mg/kg) on subunit mRNAs of N-methyl-D-aspartate (NMDA) receptors (NR1/NR2A-2C) in the rat brain by in situ hybridization using phosphor screen analysis. The level of NR1 subunit mRNA significantly increased in hippocampal complexes 1 h after a single i.p. injection of cocaine. After repeated cocaine injection, the mean scores of stereotyped behavior were increased with the number of injections. The level of NR1 subunit mRNA was obviously decreased in the striatum and cortices 24 h (early withdrawal) after a final injection following 14 days of subchronic administration. During the early withdrawal period, the amount of the NR1 subunit decreased in the nucleus accumbens, globus pallidus, and subiculum. In the dentate gyrus, the NR1 mRNA level significantly increased during early withdrawal in rats subchronically treated with cocaine. Levels of NR2B subunit mRNA were reduced in the cortices and striatum. During late withdrawal from cocaine, the level of NR2C subunit mRNA in the cerebellum was also reduced. These findings suggest that the disruption of NR1, NR2B, and NR2C subunits in the discrete brain regions occurs under the cocaine-related behavioral abnormalities and would be closely implicated in the initiation and expression of behavioral sensitization induced by repeated cocaine administration. Further studies on the changes in non-NMDA receptors are required to elucidate the biological significance of glutamate receptors for the mechanisms underlying the development of behavioral sensitization.

Anesthetics, Local↗
PubMed2002

Brain SPET abnormalities in Alzheimer's disease before and after atrophy correction.

The aim of this study was to determine which brain structures show the greatest influence of partial volume effects (PVE) in single-photon emission tomography (SPET) studies on Alzheimer's disease (AD). Brain perfusion SPET was performed in 30 patients with probable AD and 62 age-matched healthy volunteers. SPET images were corrected for PVE using grey matter volume segmented from magnetic resonance images. The most prominent changes after PVE correction were observed in the medial temporal structures. The PVE correction revealed a selective decrease in regional cerebral blood flow (rCBF) in the parahippocampal gyrus of AD without rCBF decreases in the hippocampus, which had been observed before correction. This correction seems to be essential in order to achieve accurate measurements of rCBF in SPET, which has limited spatial resolution.

Aged↗
PubMed2002

Association analysis of an (AC)n repeat polymorphism in the GABA(B) receptor gene and schizophrenia.

The human gamma-aminobutyric acid type B (GABA(B)) receptor gene is a candidate gene for schizophrenia due to its chromosomal location and neurobiologic roles. In the present study, association analyses of genetic polymorphisms of the GABA(B) receptor gene with schizophrenia were carried out in 102 unrelated schizophrenic patients and 100 healthy controls, using a polymerase chain reaction-based, single-strand conformational polymorphism analysis. Although the Ala20Val and Gly489Ser mutations were not found in our samples, we found a novel polymorphism of (AC)n dinucleotide repeats located approximately 1.6 kb upstream from the translational start site. No significant difference in allele frequencies was found between controls and patients with schizophrenia (P = 0.0587) using the Monte Carlo method. Significant differences were found between controls and patients with continuous-course schizophrenia (P = 0.0019), and between controls and patients with a positive family history of psychoses (P = 0.0015). These differences, however, were not significant after Bonferroni correction. These data did not support our hypothesis that polymorphisms of the GABA(B) receptor gene may confer vulnerability for schizophrenia.

Adult↗
PubMed2002

Brain hydrogen sulfide is severely decreased in Alzheimer's disease.

Although hydrogen sulfide (H2S) is generally thought of in terms of a poisonous gas, it is endogenously produced in the brain from cysteine by cystathionine beta-synthase (CBS). H2S functions as a neuromodulator as well as a smooth muscle relaxant. Here we show that the levels of H2S are severely decreased in the brains of Alzheimer's disease (AD) patients compared with the brains of the age matched normal individuals. In addition to H2S production CBS also catalyzes another metabolic pathway in which cystathionine is produced from the substrate homocysteine. Previous findings, which showed that S-adenosyl-l-methionine (SAM), a CBS activator, is much reduced in AD brain and that homocysteine accumulates in the serum of AD patients, were confirmed. These observations suggest that CBS activity is reduced in AD brains and the decrease in H2S may be involved in some aspects of the cognitive decline in AD.

Alzheimer Disease↗