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Articles by K Saito
Total Records ( 8 ) for K Saito
  H Ihara , T Watanabe , N Hashizume , M Totani , K Kamioka , K Onda , S Sunahara , T Suzuki , M Itabashi , Y Aoki , M Ishibashi , S Ito , K Ohashi , T Enomoto , K Saito , K Saeki , Y Nagamura , T Nobori , K Hirota , K Fujishiro , M Maekawa , M Miura and Y. Ohta
  Background

The aim of the present study was to evaluate standard reference material (SRM) 1955 commutability as a reference material for serum folate using automated methods. We also designed so as to reduce the intermethod variability present in different automated methods.

Methods

Using a microbiological assay related to the ‘information value’ of SRM 1955 as a comparison method, we investigated the possibility of standardization for the assay values of serum folate as measured by the automated methods (Access, Centaur and Elecsys). In the assay of 50 patient sera by these automated methods, we corrected observed values by the SRM 1955 and compared with comparison values.

Results

The observed values of SRM 1955 Levels I, II and III were within or outside (but near) a 95% prediction interval obtained from patient sera by the automated methods. The normalized residuals obtained from SRM 1955 were within ±3.0 (in SD units), which enabled us to conclude that the SRM 1955 had a physicochemical characterization similar to native serum. Twelve patients were assessed as hypofolataemia (<6.0 ng/mL) and 38 patients as normal (≥6.0 ng/mL). Before correction, folate levels in six of 12 patients were lower than 6.0 ng/mL, and those in seven of 38 patients were higher than 6.0 ng/mL with the automated methods. After correction, low levels were found in four of 12 patients, and normal levels were found in 33 of 38 patients.

Conclusions

The use of SRM 1955 would help to reduce the intermethod variability present in different automated methods for serum folate measurement.

  R Yamada , H Okura , T Kume , K Saito , Y Miyamoto , K Imai , T Tsuchiya , T Maehama , N Okahashi , K Obase , A Hayashida , Y Neishi , T Kawamoto and K. Yoshida
  Background—

Positive arterial remodeling and thin fibrous cap are characteristics of rupture-prone or vulnerable plaque. The natural course of the fibrous cap thickness and the relationship between serial arterial remodeling and changes in fibrous cap thickness are unknown. Therefore, the purpose of this study was to evaluate the relationship between changes in fibrous cap thickness and arterial remodeling by using optical coherence tomography (OCT) and intravascular ultrasound (IVUS) during 6-month follow-up.

Methods and Results—

Both IVUS and OCT examinations were performed on 108 vessels from 36 patients with ischemic heart disease who underwent percutaneous coronary intervention. Fifty-eight fibroatheromas were selected from 82 nonsignificant, nonculprit lesions (angiographic diameter stenosis, 25% to 75%; plaque burden, >40% by IVUS). Fibroatheroma was defined by OCT as lipid-rich plaque in >1 quadrant that has lipid. Thickness of the fibrous cap was measured by OCT. IVUS and OCT examinations were repeated at 6-month follow-up. Serial changes and relationships between IVUS indices and fibrous cap thickness were investigated. Overall, fibrous cap thickness (98.1±38.9 to 96.9±44.5 µm) as well as IVUS indices did not change significantly within 6 months. The percent changes in fibrous cap thickness correlated negatively and significantly (r=–0.54; P<0.0001; generalized estimating equation adjusted, r=–0.42; P=0.001) with the percent changes in external elastic membrane cross-sectional area.

Conclusions—

Arterial remodeling is related to changes in fibrous cap thickness. Positive arterial remodeling is not only an adaptive process, but also related to thinning of the fibrous cap.

  H Nomura , H Wada , T Mizuno , Y Yamashita , K Saito , S Kitano , N Katayama , N Yamada , T Sugiyama , A Sudo , M Usui , S Isaji and T. Nobori
 

Background: Most patients with malignant diseases are frequently complicated with some type of thrombosis, such as disseminated intravascular coagulation (DIC) or deep vein thrombosis (DVT)/pulmonary embolism (PE). Objective: The cohort and retrospective study was designed to examine the frequency of thrombosis in patients with malignant diseases and to evaluate the efficacy of D-dimer and soluble fibrin (SF) for the diagnosis of thrombosis. Patients/Methods: The plasma concentrations of D-dimer and SF were measured in patients with malignant diseases suspected of having thrombosis. D-dimer and SF were measured using a latex aggregation assay. Results: Thrombosis was observed in 23.3% of the patients with malignant diseases. Disseminated intravascular coagulation was frequently observed in patients with hepatoma, and DVT/PE was frequently observed in patients with colon cancer, lung cancer, and uterine cancer. The plasma levels of D-dimer and SF were increased in malignant diseases, especially hepatoma. Plasma levels of D-dimer and SF were significantly higher in patients with thrombosis in comparison to patients without thrombosis. A receiver operating characteristic (ROC) analysis showed the D-dimer and SF levels to be useful in the diagnosis of thrombosis. Conclusion: Elevated D-dimer and SF levels might indicate a high risk of thrombosis in patients with malignant disease; however, these assays still need to be standardized.

  H Yokoyama , S Kanno , S Takahashi , D Yamada , H Itoh , K Saito , H Sone and M. Haneda
 

Background and objectives: This study investigated whether the slope of estimated GFR is different between nonproteinuric subjects with and without diabetes, and what clinical factors are associated with the GFR slope.

Design, setting, participants, & measurements: An observational cohort study was performed in 923 subjects, and the predictive value of baseline variables on the GFR slope was investigated.

Results: On the basis of the median 3-yr follow-up and 7 measurements of GFR, GFR slope (%/yr, median and interquartile range) was significantly larger in subjects with diabetes (–2.39 (–4.86 to 0.15), n = 729) than in those without diabetes (–1.02 (–4.28 to 1.37), n = 194), and this difference remained significant with or without presence of hypertension. After adjustments for confounding factors, predictors of GFR decline were found to be baseline high values of glycosylated hemoglobin A1C (HbA1C), GFR, systolic blood pressure, and low plasma total protein in subjects with diabetes, whereas only the latter two were significant in subjects without diabetes. In subjects with diabetes, the high GFR was accounted for by high HbA1C at baseline, and the predictors of GFR decline differed between those with and without hypertension, or with high and low baseline GFR. Any combination of the predictors showed increased risk for GFR decline.

Conclusions: GFR slope is substantially affected by multiple factors at various stages. The degree of chronic hyperglycemia is likely to play a crucial role in elevating GFR and accelerating the decline in patients with type 2 diabetes even from the normoalbuminuric stage.

  K Saito , H Ishizu , M Komai , H Kotani , Y Kawamura , K. M Nishida , H Siomi and M. C. Siomi
 

PIWI-interacting RNAs (piRNAs) protect genome integrity from transposons. In Drosophila ovarian somas, primary piRNAs are produced and loaded onto Piwi. Here, we describe roles for the cytoplasmic Yb body components Armitage and Yb in somatic primary piRNA biogenesis. Armitage binds to Piwi and is required for localizing Piwi into Yb bodies. Without Armitage or Yb, Piwi is freed from the piRNAs and does not enter the nucleus. Thus, piRNA loading is required for Piwi nuclear entry. We propose that a functional Piwi–piRNA complex is formed and inspected in Yb bodies before its nuclear entry to exert transposon silencing.

  H Ide , Y Terado , S Tokiwa , K Nishio , K Saito , S Isotani , Y Kamiyama , S Muto , T Imamura and S. Horie
 

Adrenocortical cancer (ACC) is a rare and aggressive endocrine tumor. The patient presented with a large retroperitoneum tumor and lung metastases. Removal of the adrenocortical tumor with part of the transverse colon and tail of the pancreas, spleen and kidney was successfully performed following chemotherapy. Levels of serum neuron-specific enolase (NSE) were found to be markedly high before surgery and may be clinically useful markers for monitoring tumor status during management. Immunohistochemical studies showed that the cancer cells were positive for NSE and overexpression of p53. We identified a novel germ line variant of the 177 mutant (Pro to Arg; P177R) of p53 by genomic sequencing. The genetic and biochemical data presented in this case confirm the importance of screening for p53 status in ACC with inherited cancer syndrome.

  M Watanabe , H. M Hubberten , K Saito and R. Hoefgen
 

Sulfate is an essential macronutrient for plants. Plants have developed strategies to cope with sulfate deficiency, and other nutrient ion limitations. However, the regulation of these adaptive responses and the coordinating signals that underlie them are still poorly characterized. O-acetylserine (OAS) is a marker metabolite of sulfate starvation and has been speculated to have a signaling function. OAS is synthesized by the enzyme serine acetyltransferase (SERAT), which is encoded by five distinct genes in Arabidopsis. We investigated quadruple knockout mutants of SERAT that retained only one functional isoform. These mutants displayed symptoms of sulfate starvation. Furthermore, some of them displayed phenotypes typical of prolonged sulfate starvation, in particular, developmental programs associated with senescence or stress responses. Thus, we compared metabolite and transcriptome data from these mutants with N-, P-, K-, and S-depleted plants. This revealed many similarities with general nutrient-depletion-induced senescence (NuDIS), indicating the recruitment of existing regulatory programs for nutrient-starvation responses. Several candidate genes that could be involved in these processes were identified, including transcription factors and other regulatory proteins, as well as the functional categories of their target genes. These results outline components of the regulatory network controlling plant development under sulfate stress, forming a basis for further investigations to elucidate the complete network. In turn, this will advance our broader understanding of plant responses to a range of other nutrient stresses.

  K Hirai , H Kuroyanagi , Y Tatebayashi , Y Hayashi , K Hirabayashi Takahashi , K Saito , S Haga , T Uemura and S. Izumi
 

l-kynurenine 3-monooxygenase (KMO) is an NAD(P)H-dependent flavin monooxygenase that catalyses the hydroxylation of l-kynurenine to 3-hydroxykynurenine, and is localized as an oligomer in the mitochondrial outer membrane. In the human brain, KMO may play an important role in the formation of two neurotoxins, 3-hydroxykynurenine and quinolinic acid, both of which provoke severe neurodegenerative diseases. In mosquitos, it plays a role in the formation both of eye pigment and of an exflagellation-inducing factor (xanthurenic acid). Here, we present evidence that the C-terminal region of pig liver KMO plays a dual role. First, it is required for the enzymatic activity. Second, it functions as a mitochondrial targeting signal as seen in monoamine oxidase B (MAO B) or outer membrane cytochrome b5. The first role was shown by the comparison of the enzymatic activity of two mutants (C-terminally FLAG-tagged KMO and carboxyl-terminal truncation form, KMOC50) with that of the wild-type enzyme expressed in COS-7 cells. The second role was demonstrated with fluorescence microscopy by the comparison of the intracellular localization of the wild-type, three carboxyl-terminal truncated forms (C20, C30 and C50), C-terminally FLAG-tagged wild-type and a mutant KMO, where two arginine residues, Arg461-Arg462, were replaced with Ser residues.

 
 
 
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