Search PubMed⌕ Search

Biomedical subjects

T Tsutsumi

Publications and source records attributed to T Tsutsumi.

At least 19 recordsLinked to original sources
PubMed2006

Intracranial angiosarcoma arising from a schwannoma.

Angiosarcomas rarely arise from schwannomas, but we describe here a case of angiosarcoma that arose from a remnant of a benign vestibular schwannoma that had been removed 10 years earlier. The patient was a 66-year-old man with no sign of neurofibromatosis. Although we attempted surgical resection, we could not totally remove the tumour. The patient died nine months after diagnosis, primarily as result of an abscess in the cerebellum and base of the skull. The histological diagnosis was confirmed by the immunohistochemical findings of positivity for CD34 antigen and S-100 protein in the resected tumour.A review of the literature revealed four other cases of angiosarcoma with schwannoma, all of which arose from an extracranial nerve. The present case is the first report of an angiosarcoma with schwannoma arising from an intracranial locus.

Aged↗
PubMed2006

Transient electrostatic fields and related energetic proton generation with a plasma fiber.

We observe a hollow structure and a fine ring in the proton images from a petawatt scale laser interaction with a "cone-fiber" target. The protons related to the hollow structure are accelerated from the cone-tip surface and deflected later by a radial electric field surrounding the fiber. Those associated with the fine ring are accelerated from the fiber surface by this radial electric field. This field is found to decay exponentially within 3 ps from about 5 x 10(12) V/m. Two-dimensional particle-in-cell simulations produce similar proton angular distributions.

Journal Article↗
PubMed2005

Demonstration of bulk acceleration of ions in ultraintense laser interactions with low-density foams.

Ion acceleration inside low-density foams irradiated by ultraintense laser pulses has been studied experimentally and theoretically. It is found that the ion generation is closely correlated with the suppressed hot electron transport inside the foams. Particle-in-cell simulations suggest that localized electrostatic fields with multi peaks around the surfaces of lamellar layers inside the foams are induced. These fields inhibit hot electron transport and meanwhile accelerate ions inside the foams, forming a bulk acceleration in contrast to the surface acceleration at the front and rear sides of a thin solid target.

Journal Article↗
PubMed2005

Enhancement of energetic electrons and protons by cone guiding of laser light.

Energetic electrons and protons are observed when a target consisting of a reentrant cone with a disk at the tip is irradiated by a petawatt (PW) laser at an intensity of approximately 10(19) W cm(-2). The angular distribution of the electrons and protons, dependent on the open angle of the reentrant cone, is found to differ from that in the case when a target with planar geometry is used. Two jet beams are observed, in directions parallel to the cone axis and normal to the cone-shaped wall. The number and cutoff energies of the generated protons are also related to the open angle of the cone. The efficiency of the generation of energetic electrons from the cone target is 2-3 times higher than that from a simple plane target. These results indicate a guiding of the PW laser beam in the cone geometry.

Journal Article↗
PubMed2004

High-energy electrons produced in subpicosecond laser-plasma interactions from subrelativistic laser intensities to relativistic intensities.

The characteristics of the forward hot electrons produced by subpicosecond laser-plasma interactions are studied for different laser polarizations at laser intensities from subrelativistic to relativistic. The peak of the hot electron beam produced by p-polarized laser beam shifts to the laser propagation direction from the target normal direction as the laser intensity reaches the relativistic. For s-polarized laser pulse, hot electrons are mainly directed to the laser axis direction. The temperature and the maximum energy of hot electrons are much higher than that expected by the empirical scaling law. The energy spectra of the hot electrons evolve to be a single-temperature structure at relativistic laser intensities from the two-temperature structure at subrelativistic intensities. For relativistic laser intensities, the forward hot electrons are less dependent on the laser polarization under the laser conditions. The existing of a preplasma formed by the laser amplified spontaneous emission pedestal plays an important role in the interaction. One-dimensional particle-in-cell simulations reproduce the most characteristics observed in the experiment.

Journal Article↗
PubMed2004

Novel CAG/CTG repeat expansion mutations do not contribute to the genetic risk for most cases of bipolar disorder or schizophrenia.

The possible presence of anticipation in bipolar affective disorder and schizophrenia has led to the hypothesis that repeat expansion mutations could contribute to the genetic etiology of these diseases. Using the repeat expansion detection (RED) assay, we have systematically examined genomic DNA from 100 unrelated probands with schizophrenia and 68 unrelated probands with bipolar affective disorder for the presence of CAG/CTG repeat expansions. Our results show that 28% of the probands with schizophrenia and 30% of probands with bipolar disorder have a CAG/CTG repeat in the expanded range, but that each expansion could be explained by one of three nonpathogenic repeat expansions known to exist in the general population. We conclude that novel CAG/CTG repeat expansions are not a common genetic risk factor for bipolar disorder or schizophrenia.

Bipolar Disorder↗
PubMed2003

Effect of the neurotoxic dose of methamphetamine on gene expression of parkin and Pael-receptors in rat striatum.

We previously reported that haloperidol, a dopamine-D(2) receptor antagonist, induced striatal expression of parkin gene, which mutations cause autosomal recessive juvenile parkinsonism. Because of an involvement of the parkin gene defect in selective degeneration of dopaminergic neurons, we herein examined the effect of the neurotoxic dose of methamphetamine (METH; 40 mg/kg, i.p.) on gene expression of parkin and its substrate Pael-receptor (R) in the dopamine-rich areas of the rat brain, using reverse transcription-polymerase chain reaction. parkin mRNA levels in the striatum, but not in other regions, decreased at 1 and 2 h and returned to the pre-drug basal levels at 4 h after METH administration. METH also decreased Pael-R mRNA levels in the striatum and substantia nigra within 2 h after METH, while haloperidol (2 mg/kg, s.c.) increased Pael-R mRNA levels in the substantia nigra at 2 h after administration. These results suggest that temporary suppression of gene expression of parkin and Pael-R may be associated with the METH-induced dopaminergic neurotoxicity. Taken together with our previous report, dopaminergic modulation of the expression of parkin and Pael-R genes in the nigro-striatal pathway may have significant implication for pathophysiology and treatment of parkinson disease.

Animals↗
PubMed2003

Anxiety induced by repetitive transcranial magnetic stimulation is suppressed by chronic treatment of paroxetine in rats.

Repetitive transcranial magnetic stimulation (rTMS) has been shown to have a therapeutic effect on affective disorder and anxiety disorders. However, some reports have linked rTMS to a significant increase in anxiety in normal volunteers. This study investigates the effect of rTMS on anxiety and the use of acute and chronic paroxetine treatment on this animal model of anxiety. In normal rats, rTMS for 10 days induced anxiety, as shown by elevated plus maze, black and white box, and conditioned fear tests. This anxiety was suppressed by chronic, but not acute, paroxetine. These results suggest that rats receiving chronic rTMS treatment can be used as a model of anxiety and that the anxiety induced by rTMS might involve the serotonergic system.

Acute Disease↗
PubMed2001

Lack of association between a polymorphism in the promoter region of the dopamine D2 receptor and personality traits.

Disturbances of the dopaminergic neurotransmitter system have been associated with a personality trait that involves novelty seeking. A functional polymorphism in the promoter region of the dopamine D2 receptor gene (DRD2) has been reported to be associated with schizophrenia. We examined the association between this polymorphism in the DRD2 promoter region and personality traits, as assessed with the Tridimensional Personality Questionnaire. No significant association emerged between the polymorphism in the DRD2 promoter region and personality traits. Entering sex and age as covariates in an analysis of covariance did not change the results. These data fail to confirm an association between a polymorphism in the promoter region of the DRD2 and personality traits.

Adult↗
PubMed2001

Oxidative stress in the absence of inflammation in a mouse model for hepatitis C virus-associated hepatocarcinogenesis.

The mechanism of hepatocarcinogenesis in hepatitis C virus (HCV) infection is still undefined. One possibility is the involvement of oxidative stress, which can produce genetic mutations as well as gross chromosomal alterations and contribute to cancer development. We recently showed that after a long period, the core protein of HCV induces hepatocellular carcinoma (HCC) in transgenic mice with marked hepatic steatosis but without inflammation, indicating a direct involvement of HCV in hepatocarcinogenesis. To elucidate the biochemical events before the development of HCC, we examined several parameters of oxidative stress and redox homeostasis in a mouse model of HCV-associated HCC. For young mice ages 3-12 months, there was no significant difference in the levels of hydroperoxides of phosphatidylcholine (PCOOH) and phosphatidylethanolamine in liver tissue homogenates between transgenic and nontransgenic control mice. In contrast, the PCOOH level was increased by 180% in old core gene transgenic mice > 16 months old. Concurrently, there was a significant increase in the catalase activity, and there were decreases in the levels of total and reduced glutathione in the same mice. A direct in situ determination by chemiluminescence revealed an increase in hydroperoxide products by 170% even in young transgenic mice, suggesting that hydroperoxides were overproduced but immediately removed by an activated scavenger system in young mice. Electron microscopy revealed lipofuscin granules, secondary lysosomes carrying various cytoplasmic organelles, and disruption of the double membrane structure of mitochondria, and PCR analysis disclosed a deletion in mitochondrial DNA. Interestingly, alcohol caused a marked increase in the PCOOH level in transgenic mice, suggesting synergism between alcohol and HCV in hepatocarcinogenesis. The HCV core protein thus alters the oxidant/antioxidant state in the liver in the absence of inflammation and may thereby contribute to or facilitate, at least in part, the development of HCC in HCV infection.

Animals↗
PubMed2001

Frequent beta-catenin aberration in human hepatocellular carcinoma.

Recently, mutations in the beta-catenin gene in hepatocellular carcinoma (HCC) have been reported: approximately 20% of HCCs had activating mutations at the glycogen synthase kinase 3beta phosphorylation sites within the exon 3 of the beta-catenin gene. However, changes in the level of the beta-catenin protein in HCC have not been well studied. We examined, by Western blotting, the expression level of the beta-catenin protein in cancerous tissues in comparison with that in adjacent non-cancerous tissues obtained from 32 cases of HCC with hepatitis C. An increase in the beta-catenin protein level in cancerous tissue compared to that in adjacent non-cancerous tissue was found in 15 (46.9%) of 32 cases of HCC. Mutation in exon 3 of the beta-catenin gene was found in six (18.8%) of the 32 cases, in five of which the beta-catenin protein level was increased. In total, beta-catenin aberration was found in 16 (50.0%) of 32 cases of HCC. It should be noted that beta-catenin aberration was also found in early HCC although it was observed chiefly in advanced HCCs. These results indicate that beta-catenin aberration is a frequent event in the development of HCC and may facilitate the development of HCC in the course of chronic hepatitis.

Journal Article↗
PubMed2001

Quantitative assessment of severity of ventricular septal defect by three-dimensional reconstruction of color Doppler-imaged vena contracta and flow convergence region.

BACKGROUND: The aim of the present study was to investigate the feasibility and potential value of the computer-controlled, 3D, echocardiographic reconstruction of the color Doppler-imaged vena contracta (CDVC) and the flow convergence (FC) region as a means of accurately and quantitatively estimating the severity of a ventricular septal defect (VSD). METHODS AND RESULTS: We performed a 3D reconstruction of the CDVC and the FC region in 19 patients with an isolated VSD using an ultrasound system interfaced with a Tomtec computer. The variable asymmetric geometry of the CDVC and the FC region could be 3D-visualized in all patients. The 3D-measured areas of CDVC correlated well with volumetric measurements of the severity of VSD (r=0.97, P:<0.001). Regression analysis between the shunt flow rate (calculated from the product of the area of CDVC and the continuous Doppler-derived velocity time integral) and the corresponding reference results (calculated by cardiac catheterization) demonstrated a close correlation (r=0.95, P:<0.001). There was also a good correlation between shunt flow rates calculated using the conventional 2D, 1-axis measurement of the FC isovelocity surface area with the hemispheric assumption (r=0.95, P:<0.001); shunt flow rates calculated using 3D, 3-axis measurements of the FC region (r=0.97, P:<0.01); and reference results by cardiac catheterization. However, the 2D method substantially underestimated the actual shunt flow rate. CONCLUSIONS: The 3D reconstruction of the CDVC and the FC region may aid in quantifying the severity of VSD.

Child↗
PubMed2001

Increase in the concentration of carbon 18 monounsaturated fatty acids in the liver with hepatitis C: analysis in transgenic mice and humans.

Steatosis is one of the histologic characteristics of chronic hepatitis C and is well reproduced in a transgenic mouse model for hepatocellular carcinoma (HCC) in which the core protein of hepatitis C virus (HCV) plays a pivotal role in inducing steatosis and HCC. In the present study, the lipid composition in the liver of the HCV core gene transgenic mice as well as in those of chronic hepatitis C patients was determined. The concentration of carbon 18 monounsaturated (C18:1) fatty acids, such as oleic and vaccenic acids, which are known to increase membrane fluidity leading to higher cell division rates, significantly increased in the livers of transgenic mice compared to nontransgenic control mice. The concentration of C18:1 fatty acids also significantly increased in the livers of chronic hepatitis C patients compared to subjects without HCV infection. These results suggest that HCV may affect a specific pathway in the lipid metabolism and cause steatosis in the liver.

Animals↗
PubMed2001

Adsorption mechanism of hexavalent chromium by redox within condensed-tannin gel.

We have proposed a new recovery system of hexavalent chromium Cr(VI) that is of great toxicity utilizing condensed-tannin gels derived from a natural polymer with many polyhydroxyphenyl groups. The adsorption mechanism of Cr(VI) to the tannin molecules was clarified. The adsorption mechanism consists of four reaction steps; the esterification of chromate with tannin molecules, the reduction of Cr(VI) to trivalent chromium Cr(III), the formation of carboxyl group by the oxidation of tannin molecules and the ion exchange of the reduced Cr(III) with the carboxyl and hydroxyl groups. It was found in this recovery system that a large amount of proton was consumed accompanied with the reduction of Cr(VI) so that the acidic solution containing Cr(VI) was transferred automatically to neutral one by choosing an appropriate initial pH. The carboxyl group which was created by the oxidation of tannin molecules parallel to the reduction of Cr(VI) to Cr(III) contributed to an increase in the ion-exchange sites of the reduced Cr(III). The maximum adsorption capacity of Cr(VI) reached 287 mg Cr/g dry tannin gel under the conditions of 0.77 water content of tannin gel and the initial pH = 2. This adsorption capacity was five to ten times higher than that obtained by the ion exchange between ordinary Cr(III) and tannin molecules for the tannin gels prepared under similar conditions. The system proposed here will provide an important information on a zero-emission-oriented process because it has such advantages as higher adsorption capacity of chromium and lower volume of secondary wastes compared with conventional process.

Adsorption↗
PubMed2001

Update of daily intake of PCDDs, PCDFs, and dioxin-like PCBs from food in Japan.

Total diet study (TDS) samples of 14 food groups from 16 locations in Japan, collected in 1999 and 2000, were analyzed for polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (dioxin-like PCBs) to estimate the update of daily intake of these contaminants from food. The mean daily intake of toxic equivalency (TEQ) for an adult weighing 50 kg, calculated at non-detected isomer concentrations equal to zero (ND = 0), was estimated to be 2.25 pg TEQ/kg b.w./day. When non-detected isomer concentrations are assumed to be equal to half of the limits of detection (ND = 1/2 LOD), the mean daily intake was estimated to be 3.22 pg TEQ/kg b.w./day. These values were below the tolerable daily intake (TDI) of 4 pg TEQ/kg b.w. for PCDD/Fs and dioxin-like PCBs set in Japan. In both the estimates, the mean daily intakes were highest from fish and shellfish (76.9% at ND = 0 and 53.9% at ND = 1/2 LOD of the total TEQs), followed by those from meat and eggs (15.5% at ND = 0 and 11.7% at ND = 1/2 LOD of the total TEQs). Congener specific data revealed that these total TEQ levels were dominated by 1,2,3,7,8-PeCDD, 2,3,4,7,8-PeCDF and 3,3',4,4',5-PeCB in each case (71.7% at ND = 0 and 63.1% at ND = 1/2 LOD of the total TEQs). The dioxin-like PCBs (non-ortho and mono-ortho PCBs) accounted for about 50% of these total TEQs. These data will be very useful in the risk assessment of PCDD/Fs and dioxin-like PCBs from food in Japan.

Adult↗
PubMed2001

Frequent presence of HBV in the sera of HBsAg-negative, anti-HBc-positive blood donors.

BACKGROUND: Recent studies have revealed that HBV may not be cleared even after the disappearance of serum HBsAg. The purpose of this study was to investigate whether the replication of HBV persists in HBsAg-negative blood donors who lack apparent liver disease. STUDY DESIGN AND METHODS: Serum HBV was examined by using PCR coupled with Southern blotting in 50 blood donors who were identified to be HBsAg negative but anti-HBc positive. RESULTS: HBV DNA was detected in the sera from 19 (38%) of 50 donors. In 11 of the 19, HBV existed exclusively as immune complexes, while HBV presumably did not exist as immune complexes in the remaining eight. The levels of HBV DNA were similar to those in patients who had recovered from acute HBV. Some nucleotide substitutions, which did not confer amino acid changes in the major epitope of HBsAg, were found in the preS-S regions. CONCLUSION: The replication of HBV is ongoing in a substantial proportion of healthy blood donors who have anti-HBc. Blood from such donors may contain very low levels of HBV free of immune complex formation and should be excluded for transfusion. The fact that such blood donors apparently lacked liver disease suggests no pathogenicity of such "occult" HBV.

Adult↗
PubMed2001

Suppression of conditioned fear by administration of CCKB receptor antisense oligodeoxynucleotide into the lateral ventricle.

We investigated the role of CCK in the development of anxiety by determining whether CCKB receptor antisense suppressed intracellular Ca(2+) concentration in vitro or suppressed conditioned fear stress in vivo. First, for the in vitro studies, we used rat pituitary tumor GH3 cells since these cells have CCKB receptors. GH3 cells were stimulated by 10 microM CCK-4; intracellular Ca(2+) concentration was measured. The CCKB receptor antisense at 1 or 10 microM reduced the subsequent response to 10 microM CCK-4 in a time-dependent manner. Second, for the in vivo studies, the CCKB receptor antisense, sense, random sense, or saline was infused at a constant rate for 6 days into rat lateral ventricles via mini-osmotic pumps. Individual rats were then subjected to 30 min of inescapable electric footshock in a chamber with a grid floor. Twenty-four hours later, the rat was again placed in the chamber and observed for 5 min without shocks. This study showed that CCKB receptor antisense significantly suppressed intracellular Ca(2+) concentration in GH3 cells and significantly reduced freezing behavior in rats, indicating that the CCKB receptor plays an important role in anxiety.

Animals↗