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Articles by T Sato
Total Records ( 8 ) for T Sato
  M Adachi , S Mugikura , A Shibata , E Kawaguchi , T Sato and S. Takahashi
 

BACKGROUND AND PURPOSE: In reviewing MR images of patients with spontaneous intracranial hypotension (SIH), we found an accentuated decrease in the subcortical white matter on fluid-attenuated inversion recovery (FLAIR) images. Our aim was to determine whether the signal intensity of the subcortical white matter decreases on FLAIR and T2-weighted images in SIH.

MATERIALS AND METHODS: We retrospectively examined pretreatment MR images including 7 FLAIR and 10 T2-weighted images obtained from 10 patients with SIH and follow-up images (5 FLAIR and 7 T2-weighted images). Two observers measured the signal intensities in the subcortical white matter on MR images at the level of the centrum semiovale and, to calculate the signal intensity ratios, measured those of the adjacent cortex and corpus callosum. Furthermore, 4 observers performed visual evaluation for accentuated signal intensity decreases for receiver operating characteristic (ROC) analysis.

RESULTS: The intensity ratios of the subcortical white matter, both to the adjacent cortex and corpus callosum, were significantly different between the control and pretreatment images in SIH and between pretreatment and follow-up images in SIH on FLAIR images, whereas these showed no significant differences between the control and follow-up images in SIH. On visual inspection, an accentuated decrease in signal intensity in the subcortical white matter was shown on pretreatment FLAIR images, which returned to the control level on follow-up images. However, on the T2-weighted images we could hardly recognize the decrease in the signal intensity.

CONCLUSIONS: Awareness of the decreased signal intensity of the subcortical white matter on FLAIR images could help in the diagnosis of SIH.

  I Nozaki , T Hamaguchi , N Sanjo , M Noguchi Shinohara , K Sakai , Y Nakamura , T Sato , T Kitamoto , H Mizusawa , F Moriwaka , Y Shiga , Y Kuroiwa , M Nishizawa , S Kuzuhara , T Inuzuka , M Takeda , S Kuroda , K Abe , H Murai , S Murayama , J Tateishi , I Takumi , S Shirabe , M Harada , A Sadakane and M. Yamada
 

We analysed the epidemiological data and clinical features of patients with prion diseases that had been registered by the Creutzfeldt-Jakob Disease Surveillance Committee, Japan, over the past 10 years, since 1999. We obtained information on 1685 Japanese patients suspected as having prion diseases and judged that 1222 patients had prion diseases, consisting of definite (n = 180, 14.7%) and probable (n = 1029, 84.2%) cases, except for dura mater graft-associated Creutzfeldt–Jakob disease which also included possible cases (n = 13, 1.1%). They were classified into 922 (75.5%) with sporadic Creutzfeldt–Jakob disease, 216 (17.7%) with genetic prion diseases, 81 (6.6%) with acquired prion diseases, including 80 cases of dura mater graft-associated Creutzfeldt–Jakob disease and one case of variant Creutzfeldt–Jakob disease, and three cases of unclassified Creutzfeldt–Jakob disease (0.2%). The annual incidence rate of prion disease ranged from 0.65 in 1999 to 1.10 in 2006, with an average of 0.85, similar to European countries. Although methionine homozygosity at codon 129 polymorphism of the prion protein gene was reported to be very common (93%) in the general Japanese population, sporadic Creutzfeldt–Jakob disease in Japan was significantly associated with codon 129 homozygosity (97.5%), as reported in western countries. In sporadic Creutzfeldt–Jakob disease, MM1 type (Parchi’s classification) is the most common, as in western countries. Among atypical sporadic Creutzfeldt–Jakob disease cases, the MM2 type appeared most common, probably related to the very high proportion of methionine allele in the Japanese population. As for iatrogenic Creutzfeldt–Jakob disease, only dura mater graft-associated Creutzfeldt–Jakob disease cases were reported in Japan and, combined with the data from previous surveillance systems, the total number of dura mater graft-associated Creutzfeldt–Jakob disease was 138, comprising the majority of worldwide dura mater graft-associated Creutzfeldt–Jakob disease patients. Regarding genetic prion diseases, the most common mutation of prion protein gene was V180I (41.2%), followed by P102L (18.1%), E200K (17.1%) and M232R (15.3%), and this distribution was quite different from that in Europe. In particular, V180I and M232R were quite rare mutations worldwide. Patients with V180I or M232R mutations rarely had a family history of prion diseases, indicating that a genetic test for sporadic cases is necessary to distinguish these from sporadic Creutzfeldt–Jakob disease. In conclusion, our prospective 10-year surveillance revealed a frequent occurrence of dura mater graft-associated Creutzfeldt–Jakob disease, and unique phenotypes of sporadic Creutzfeldt–Jakob disease and genetic prion diseases related to the characteristic distribution of prion protein gene mutations and polymorphisms in Japan, compared with those in western countries.

  T Sato , K Nishishita , Y Okada and K. Toda
 

Temperature sensitivity of frog taste cells was studied. The taste cell designated Type thermosensitive (TS) I cell was depolarized by warm stimulus at 30 °C and hyperpolarized by cold stimulus at 10 °C. The taste cell designated Type TS II cell was depolarized by the cold stimulus and hyperpolarized by the warm stimulus. Menthol solution at 20 °C, which selectively activates transient receptor potential (TRP) M8 channels sensitive to cold stimuli, depolarized Type TS II cells but not Types TS I cells. Thermal stimuli–induced receptor potentials were all blocked by a nonselective cation channel blocker flufenamic acid. The results indicate that Type TS I cells have warm sensor channels alone, Type TS II cells have cold sensor channels alone and both the channels are a nonselective cation channel. The candidate of cold sensor channel in Type TS II cells is a TRPM8 channel and that of warm sensor channel in Type TS I cells is likely to be a TRPM4-like channel from the published data. In a subset of taste cells, Types TS III and TS IV cells were found. The former was depolarized by both cold and warm stimuli, but the latter was hyperpolarized by both stimuli. Types TS III and TS IV cells might have both TRPM4-like and TRPM8 channels. It is supposed that depolarizations induced by both cold and warm stimuli were dominant in Type TS III cells and hyperpolarizations induced by both the thermal stimuli were dominant in Type TS IV cells.

  Y Ikeda , K. i Aihara , S Yoshida , T Sato , S Yagi , T Iwase , Y Sumitomo , T Ise , K Ishikawa , H Azuma , M Akaike , S Kato and T. Matsumoto
 

Age-related andropause promotes cardiovascular disease in males. Although we had previously reported that the androgen-androgen receptor (AR) system plays important roles in cardiac growth and remodeling, the system’s involvement in vascular remodeling remains unclear. To clarify this role, 25-wk-old male AR knockout (ARKO) mice and littermate male wild-type (WT) mice were divided into two groups with and without angiotensin II (Ang II) administration (2.0 mg/kg · d) for 14 d, respectively. No morphological differences in the coronary artery and thoracic aorta were observed between the groups without Ang II. Ang II stimulation markedly increased medial thickness and perivascular fibrosis in ARKO mice, with enhanced TGF-β1, collagen type I, and collagen type III gene expression in the aorta. Ang II stimulation also prominently increased superoxide production, lipid peroxidation, and gene expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase components in ARKO mice compared with WT mice. In addition, phosphorylation of c-Jun N-terminal kinase (JNK) and phosphorylated (Smad2/3) was remarkably enhanced in Ang II-treated ARKO mice compared with Ang II-treated WT mice. Notably, daily urinary nitric oxide (NO) metabolites excretion as a marker of NO bioavailability, aortic endothelial NO synthase expression and phosphorylation, and Akt phosphorylation were significantly reduced in ARKO mice compared with WT mice, regardless of Ang II stimulation. In conclusion, the androgen-AR system is required for the preservation of NO bioavailability through Akt-endothelial NO synthase system activation and exerts protective effects against Ang II-induced vascular remodeling by regulating oxidative stress, c-Jun N-terminal kinase (JNK) signaling, and the TGF-β-phosphorylated Smad pathway.

  K Sato , T Sato , J Furuse , H Kasugai , M Konishi , T Kosuge , A Saito , Y Sasaki , K Takasaki and T. Okusaka
  Objective

The aim of this study was to explore why patients accepted or declined to participate in a randomized clinical trial, which was subsequently discontinued because of a low recruitment rate.

Methods

Forty-one patients were invited to participate in a randomized clinical trial that aimed to compare local ablation therapies and surgery to treat small asymptomatic hepatocellular carcinomas. These patients were then asked to answer a questionnaire that assessed patient perception and reasons for accepting or declining to enroll in the randomized clinical trial. When patients had a strong preference for a specific treatment, the questionnaire assessed why, how and when they had chosen it.

Results

The response rate was 6/6 (100%) and 30/35 (86%) for the participant and non-participant groups, respectively. Among the 30 non-participants, 23 had a strong preference for local ablation therapies, which was less invasive and offered shorter hospitalization. Patient preference for a specific treatment often stemmed from their consultations with a clinician who referred them to a specialist hospital. Patients without strong preference for a specific treatment participated in the randomized clinical trial because of altruistic motivations.

Conclusion

When new treatments that are innovative and less burdensome become widespread, they are difficult to compare with standard therapy utilizing a well-designed randomized clinical trial. Consequently, when an innovative treatment is developed, investigators should consider designing a randomized clinical trial as early as possible.

  Y Ikeda , K. i Aihara , M Akaike , T Sato , K Ishikawa , T Ise , S Yagi , T Iwase , Y Ueda , S Yoshida , H Azuma , K Walsh , T Tamaki , S Kato and T. Matsumoto
 

Doxorubicin (Dox) has been used as a potent anticancer agent, but serious cardiotoxicity precludes its use in a wide range of patients. We have reported that the androgen-androgen receptor (AR) system plays important roles in cardiac growth and protection from angiotensin II-induced cardiac remodeling. The present study was undertaken to clarify whether the androgen-AR system exerts a cardioprotective effect against Dox-induced cardiotoxicity. Male AR knockout (ARKO) and age-matched littermate male wild-type (WT) mice at 25 wk of age were given ip injections of Dox (20 mg/kg) or a vehicle. The survival rate and left ventricular function in Dox-treated male ARKO mice were reduced compared with those in Dox-treated male WT mice. Electron microscopic study showed prominent vacuole formation of myocardial mitochondria in Dox-treated male ARKO mice. Cardiac oxidative stress and apoptosis of cardiomyocytes were increased more prominently by Dox treatment in male ARKO mice than in male WT mice. In addition, Dox-induced reduction in the expression of cardiac mitochondria transcription factor A (Tfam) and phosphorylation of serine-threonine kinase (Akt) was more pronounced in male ARKO mice than in male WT mice. In cardiac myoblast cells, testosterone up-regulated Akt phosphorylation and Tfam expression and exerted an antiapoptotic effect against Dox-induced cardiotoxicity. Collectively, the results demonstrate that Dox-induced cardiotoxicity is aggravated in male ARKO mice via exacerbation of mitochondrial damage and superoxide generation, leading to enhanced apoptosis of cardiomyocytes. Thus, the androgen-AR system is thought to counteract Dox-induced cardiotoxicity partly through activation of the Akt pathway and up-regulation of Tfam to protect cardiomyocytes from mitochondrial damage and apoptosis.

  M Ruprecht , T Bionda , T Sato , M. S Sommer , T Endo and E. Schleiff
 

Protein translocation across membranes is a fundamental cellular process. The majority of the proteins of organelles such as mitochondria and chloroplasts is synthesized in the cytosol and subsequently imported in a post-translational manner. The precursor proteins have to be unfolded at least for translocation, but it has also been assumed that they are unfolded during transport to the organelle in the cytosol. Unfolding is governed by chaperones and the translocon itself. At the same time, chaperones provide the energy for the import process. The energetic properties of the chloroplast translocon were studied by import of the Ig-like module of the muscle protein titin fused to the transit peptide of the chloroplast targeted oxygen evolving complex subunit of 33 kDa (OE33). Our results suggest that p(OE33)titin is folded prior to import and that translocation is initiated by unfolding after having bound to the translocon at the chloroplast surface. Using a set of stabilizing and destabilizing mutants of titin previously analyzed by atomic force microscopy and as passenger for mitochondrial translocation, we studied the unfolding force provided by the chloroplast translocon. Based on these results, a model for translocation is discussed.

  T Takahashi , T Ida , T Sato , Y Nakashima , Y Nakamura , A Tsuji and M. Kojima
 

Ghrelin was originally isolated from rat stomach as an endogenous ligand for the GH secretagogue receptor. The major active form of ghrelin is a 28-amino acid peptide modified by an n-octanoic acid on the serine 3 residue, and this lipid modification is essential for the biological activity of ghrelin. However, it is not clear whether prohormone convertase (PC) and ghrelin O-acyltransferase (GOAT) are the minimal requirements for synthesis of acyl-modified ghrelin in cultured cells. By using three cultured cell lines, TT, AtT20 and COS-7, in which the expression levels of processing proteases and GOAT vary, we examined the processing patterns of ghrelin precursor. We found that not only PC1/3 but also both PC2 and furin could process proghrelin to the 28-amino acid ghrelin. Moreover, the presence of PC and GOAT in the cells, as well as n-octanoic acid in the culture medium, was necessary to produce n-octanoyl ghrelin.

 
 
 
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