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Articles by K Nakamura
Total Records ( 13 ) for K Nakamura
  N Ishimine , Y Usami , S Nogi , T Sumida , Y Kurihara , K Matsuda , K Nakamura , K Yamauchi , N Okumura and M. Tozuka
  Background

In human serum, a portion of homocysteine (Hcy) exists as an N-linked form to the -amino group of protein lysine residues. N-homocysteinylated proteins differ structurally and functionally from native proteins. The present study strives to develop detection and potential semi-quantification methods for N-homocysteinylated apolipoprotein AI (N-Hcy-apoAI) in human serum.

Methods

Serum treated with or without cysteamine was supplied to isoelectric focusing (IEF) followed by an immunoblot using an anti-apoAI antibody. Cysteamine treatment increased the isoelectric point for N-Hcy-apoAI, but not for unmodified apoAI, due to the presence of -SH group(s) derived from Hcy and the absence of a cysteine residue in the apoAI molecule. N-Hcy-apoAI was semi-quantified from the scanned immunoblot pattern via a computer.

Results

After cysteamine treatment, N-Hcy-apoAI in the serum was identified by IEF at the position with a higher pI value compared with intact apoAI. The reproducibility (between assays) of the semi-quantification method was 19.1% CV (coefficient of variation) for an average ratio 5.9% of N-Hcy-apoAI to the whole apoAI in the serum. Approximately 1.0–7.4% of apoAI was N-homocysteinylated in the serum obtained from 27 healthy subjects. Neither the ratio of N-Hcy-apoAI nor its concentration, calculated by total apoAI concentration, indicated correlation with the so-called total (free and S-linked) Hcy concentration.

Conclusions

We directly found that a portion of apoAI in the serum undergoes homocysteinylation in an N-linkage manner, and used this to develop a potential semi-quantification method for N-Hcy-apoAI.

  K Nakamura , Y Sekine , Y Ouchi , M Tsujii , E Yoshikawa , M Futatsubashi , K. J Tsuchiya , G Sugihara , Y Iwata , K Suzuki , H Matsuzaki , S Suda , T Sugiyama , N Takei and N. Mori
 

Context  Autism is a neurodevelopmental disorder that is characterized by repetitive and/or obsessive interests and behavior and by deficits in sociability and communication. Although its neurobiological underpinnings are postulated to lie in abnormalities of the serotoninergic and dopaminergic systems, the details remain unknown.

Objective  To determine the occurrence of changes in the binding of serotonin and dopamine transporters, which are highly selective markers for their respective neuronal systems.

Design  Using positron emission tomography, we measured the binding of brain serotonin and dopamine transporters in each individual with the radioligands carbon 11 (11C)–labeled trans-1,2,3,5,6,10-β-hexahydro-6-[4-(methylthio)phenyl]pyrrolo-[2,1-a]isoquinoline ([11C](+)McN-5652) and 2β-carbomethoxy-3-β-(4-fluorophenyl)tropane ([11C]WIN-35,428), respectively. Statistical parametric mapping was used for between-subject analysis and within-subject correlation analysis with respect to clinical variables.

Setting  Participants recruited from the community.

Participants  Twenty men (age range, 18-26 years; mean [SD] IQ, 99.3 [18.1]) with autism and 20 age- and IQ-matched control subjects.

Results  Serotonin transporter binding was significantly lower throughout the brain in autistic individuals compared with controls (P < .05, corrected). Specifically, the reduction in the anterior and posterior cingulate cortices was associated with the impairment of social cognition in the autistic subjects (P < .05, corrected). A significant correlation was also found between repetitive and/or obsessive behavior and interests and the reduction of serotonin transporter binding in the thalamus (P < .05, corrected). In contrast, the dopamine transporter binding was significantly higher in the orbitofrontal cortex of the autistic group (P < .05, corrected in voxelwise analysis). In the orbitofrontal cortex, the dopamine transporter binding was significantly inversely correlated with serotonin transporter binding (r = –0.61; P = .004).

Conclusions  The brains of autistic individuals have abnormalities in both serotonin transporter and dopamine transporter binding. The present findings indicate that the gross abnormalities in these neurotransmitter systems may underpin the neurophysiologic mechanism of autism. Our sample was not characteristic or representative of a typical sample of adults with autism in the community.

  Y Kushi , H Kamimiya , H Hiratsuka , H Nozaki , H Fukui , M Yanagida , M Hashimoto , K Nakamura , S Watarai , T Kasama , H Kajiwara and T. Yamamoto
 

Bacterial sialyltransferases (STs) from marine sources were characterized using glycosphingolipids (GSLs). Bacterial STs were found to be β-galacotoside STs. There were two types of STs: (1) ST obtained from strains such as ishi-224, 05JTC1 (#1), ishi-467, 05JTD2 (#2), and faj-16, 05JTE1 (#3), which form 2-3 sialic acid (Sia) linkages, named 2-3ST, (2) ST obtained from strains such as ISH-224, N1C0 (#4), pda-rec, 05JTB2 (#5), and pda-0160, 05JTA2 (#6), which form 2-6 Sia linkages, named 2-6ST. All STs showed affinity to neolacto- and lacto-series GSLs, particularly in neolactotetraosyl ceramide (nLc4Cer). No large differences were observed in the pH and temperature profiles of enzyme activities. Kinetic parameters obtained by Lineweaver–Burk plot analysis showed that #3 and #4 STs had practical synthetic activity and thus it became easily possible to achieve large-scale ganglioside synthesis (100–300 µM) using these recombinant enzymes. Gangliosides synthesized from nLc4Cer by 2-3 and 2-6STs were structurally characterized by several analytical and immunological methods, and they were identified as IV3NeuAc-nLc4Cer(S2-3PG) and IV6NeuAc-nLc4Cer (S2-6PG), respectively. Further characterization of these STs using lactotetraosylceramide (Lc4Cer), neolactohexaosylceramide (i antigen), and IV6kladoLc8Cer (I antigen) showed the synthesis of corresponding gangliosides as well. Synthesized gangliosides showed binding activity to the influenza A virus [A/panama/2007/99 (H3N2)] at a similar level to purified S2-3PG and S2-6PG from mammalian sources. The above evidence suggests that these STs have unique features, including substrate specificities restricted to lacto- and neolactoseries GSLs, as well as catalytic potentials for ganglioside synthesis. This demonstrates that efficient in vitro ganglioside synthesis could be a valuable tool for selectively synthesizing Sias modifications, thereby permitting the exploration of unknown functions.

  H Nozaki , M Yanagida , K. i Koide , K Shiotani , M Kinoshita , Y Kobayashi , S Watarai , K Nakamura , A Suzuki , T Ariga and Y. Kushi
 

We have established hybridoma cell lines producing monoclonal antibodies (mAbs) directed to N-acetylglucosaminylβ1-3galactose (GlcNAcβ1-3Gal) residue by immunizing BALB/c mice with lactotriaosylceramide (Lc3Cer). These obtained hybridoma cells, specific to Lc3Cer, were dual immunoglobulin (Ig)-producing cells which secreted both IgM and IgG molecules as antibodies. The established mAbs are able to react with not only Lc3Cer but also GlcNAcβ1-3-terminal glycosphingolipids (GSLs) despite branching or lactosamine chain lengths and human transferrin with terminal GlcNAc residues. Comparison of the variable regions of the cloned IgM and IgG by reversed transcription-polymerase chain reaction analysis confirmed that the variable regions determine the specificity, the other amino acids are conserved, and these mAbs are encoded by J558 and V-21family genes. Furthermore, we have analyzed the expression of GSLs with GlcNAcβ1-3 epitope in acute leukemia cell lines and mouse fetal tissues using these mAbs, in which antigens were distributed comparatively. These mAbs are useful for studying the precise distribution of GlcNAcβ1-3Gal-terminating GSL expression in tissues as well as for detecting GSLs carrying terminal GlcNAcβ1-3Gal carbohydrate structure.

  Y Kanemitsu , T Kato , Y Shimizu , Y Inaba , Y Shimada , K Nakamura , A Sato , Y Moriya and for the Colorectal Cancer Study Group (CCSG) of Japan Clinical Oncology Group
 

A randomized controlled trial is being conducted in Japan to compare hepatectomy alone with hepatectomy followed by adjuvant chemotherapy as treatment in patients with curatively resected liver metastases from colorectal cancer to improve survival with intensive chemotherapy. Between 42 and 70 days after liver resection, patients are randomly assigned to either hepatectomy alone or hepatectomy followed by 12 cycles of modified FOLFOX6 (mFOLFOX6) regimen. A total of 300 patients (including 78 patients in Phase II) will be accrued from 38 institutions within 3 years. The primary endpoint is treatment compliance at nine courses of mFOLFOX6 regimen in Phase II and disease-free survival in Phase III. The secondary endpoints are overall survival, incidence of adverse events and patterns of recurrence.

  K Nakamura , M Tahara , N Kiyota , R Hayashi , T Akimoto , H Fukuda , M Fujii and N. Boku
 

A Phase II study was started in Japan to evaluate the efficacy and safety of concurrent chemoradiotherapy with S-1 plus cisplatin in patients with unresectable locally advanced squamous cell carcinoma of the head and neck. This study began in July 2008, and a total of 45 patients will be accrued from 13 institutions within 2 years. The primary endpoint is the clinical complete remission rate. The secondary endpoints are local progression-free survival, overall survival, progression-free survival, time to treatment failure, proportion of patients who achieve nutritional support-free survival and adverse events.

  K Nakamura , K Ogawa , T Sasaki , H Onishi , M Koizumi , M Araya , N Mukumoto , M Mitsumori , T Teshima and Japanese Patterns of Care Study Working Subgroup of Prostate Cancer
  Objective

The purpose of this study is to identify the treatment planning process for Japanese patients with localized prostate cancer.

Methods

The Patterns of Care Study conducted a random survey of 61 institutions nationwide. Detailed information was collected on prostate cancer patients without distant metastases who were irradiated during the periods 2003–05. Radiation treatment planning and delivery were evaluated in 397 patients who were treated radically with external photon beam radiotherapy.

Results

Computed tomography data were used for planning in ~90% of the patients. Contrast was rarely used for treatment planning. Simulations and treatments were performed in the supine position in almost all patients. Immobilization devices were used in only 15% of the patients. Verification of the treatment fields using portal films or electric portal imaging devices was performed in most of the patients. However, regular or multiple verifications in addition to initial treatment and/or portal volume changes were performed in only 30% of the patients. Typical beam arrangements for treatment of the prostate consisted of a four-field box. Three-dimensional conformal techniques were applied less frequently in non-academic hospitals than in academic ones. Modernized multileaf collimators with leaf widths ≤10 mm were used in about two-thirds of the patients. Although the total doses given to the prostate were affected by the leaf widths, there were no significant differences between leaf widths of 5 and 10 mm.

Conclusions

The results of the survey identified certain patterns in the current treatment planning and delivery processes for localized prostate cancer in Japan.

  K Nakamura , H Saji , R Nakajima , M Okada , H Asamura , T Shibata , S Nakamura , H Tada and M. Tsuboi
 

A Phase III study was started in Japan to evaluate the non-inferiority in overall survival of segmentectomy compared with lobectomy in patients with small-sized (diameter ≤2 cm) peripheral non-small cell lung cancer, excluding radiologically determined non-invasive cancer. This study began in August 2009, and a total of 1100 patients will be accrued from 71 institutions within 3 years. The primary endpoint is overall survival. The secondary endpoints are post-operative respiratory function, relapse-free survival, proportion of local recurrence, adverse events, proportion of patients who complete segmentectomy, duration of hospitalization, duration of chest tube placement, operation time, blood loss and number of auto-sutures used. This study is one of the first intergroup studies in Japan between the Japan Clinical Oncology Group and the West Japan Oncology Group.

  A Takashima , C Morizane , H Ishii , K Nakamura , H Fukuda , T Okusaka and J. Furuse
 

A randomized Phase II selection design trial comparing gemcitabine plus S-1 combination therapy with S-1 monotherapy for chemo-naïve unresectable or recurrent biliary tract cancer patients was started in Japan. The aim of this trial is to evaluate the efficacy and safety of the two regimens and to determine which is more promising as a test arm regimen to be compared with the current standard regimen, gemcitabine plus cisplatin, in a subsequent Phase III trial. Patients with unresectable or recurrent biliary tract cancer are randomized to either gemcitabine plus S-1 combination therapy arm or S-1 monotherapy arm. A total of 100 patients will be accrued for this study from 18 institutions over 1 year. The primary endpoint is the proportion of 1-year overall survival, and the secondary endpoints are progression-free survival, response rate and adverse events.

  K Nakamura , H. E. F Palmer , T Ozawa and K. Mashima
 

Protein tyrosine phosphatase (PTP)-PEST is expressed in a wide variety of several cell types and is an efficient regulator of cell adhesion, spreading and migration. PTP-PEST-associating molecules are important in elucidating the function of PTP-PEST. Herein, we have identified protein phosphatase 1 (PP1) as a novel PTP-PEST binding protein, and then we aimed to determine how PP1 contributes to the phosphorylation at Ser39 of PTP-PEST, whose phosphorylation suppresses PTP-PEST enzymatic activity. The HEK 293 cells overexpressing exogenous PTP-PEST were stimulated by 12-O-tetradecanoylphorbol 13-acetate (TPA) and the phosphorylation of PTP-PEST at Ser39 was evaluated using an anti-phospho-Ser39 PTP-PEST specific antibody (anti-pS39-PEST Ab). It was demonstrated that the phosphorylation at Ser39 detected by anti-pS39-PEST Ab was dependent on TPA treatment and a significant inverse correlation between the PTP activity of PTP-PEST and anti-pS39-PEST Ab-immunoreactive band intensity. The phosphorylation of Ser39 was suppressed by co-transfection of a plasmid encoding wild-type PP1, but not by that of the dominant-negative PP1 mutant. Furthermore, TPA-induced phosphorylation could take place in PTP-PEST catalytic domain, but the phosphorylation of PTP-PEST catalytic domain could not be abrogated by co-transfection of a plasmid expressing wild-type PP1. In conclusion, PP1 associates with the non-catalytic domain of PTP-PEST and regulates PTP activity via dephosphorylation of phospho-Ser39.

  H Yanai , K Nakamura , S Hijioka , A Kamei , T Ikari , Y Ishikawa , E Shinozaki , N Mizunuma , K Hatake and A. Miyajima
 

Delta-like 1 protein (Dlk-1), also known as preadipocyte factor 1 (Pref-1), is a transmembrane and secreted protein with epidermal growth factor (EGF)-like repeats. Dlk-1 is known to be expressed in foetal liver, but absent in neonatal and adult liver in mice and rats. Dlk-1 is also expressed in a subpopulation of hepatic oval cells, which are considered as stem/progenitor cells in rat adult liver. In this study, we generated monoclonal antibodies against human Dlk-1 (hDlk-1) and investigated hDlk-1 expression in human liver and hepatocellular carcinoma (HCC). Like rodent livers, hDlk-1 was detected in foetal liver, but not in adult liver. In HCC, hDlk-1 was positive for 20.5% of the cases examined and was localized in both cytoplasm and cell membrane, whereas hDlk-1 was undetected in viral hepatitis, nodular cirrhosis. Interestingly, hDlk-1 positive HCC was found more frequently in younger patients and its expression was correlated with alpha-fetoprotein expression. Furthermore, hDlk-1 was also detected frequently in colon adenocarcinomas (58%), pancreatic islet carcinoma (50%), and small cell lung carcinoma (50%). Thus, hDlk-1 is a cell surface protein expressed in many carcinomas including HCC and may be a potential target for monoclonal antibody therapy for carcinomas.

  H Tamaki , T Matsuoka , Y Yasuda , S Hanada , Y Kamagata , K Nakamura and S. i. Sakasegawa
 

A unique urate-oxidizing enzyme was identified in a bacterium, strain T-15. Based on its phylogenetic, physiological and biochemical properties, strain T-15 was deemed to be a novel species within the genus Lysobacter. The enzyme expressed in Lysobacter sp. T-15 was composed of 592 amino acids and contained four consensus copper-binding sites, and the recombinant enzyme was, at least in this study, speculated to have three Cu ions per subunit. The primary structure of the enzyme was 33% identical to Marinomonas mediterranea polyphenol oxidase, but it showed no significant similarity to any known urate oxidase. With urate as the substrate, the catalytic efficiency (kcat/Km) of recombinant enzyme was 4.0 x 102 s1mM1, and it was not inhibited by xanthine, a strong urate oxidase inhibitor. The enzyme also showed activity toward 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid), 2,6-dimethoxyphenol and bilirubin, with catalytic efficiencies of 4.9 x 102, 1.1 x 102 and 3.6 x 103 s1mM1, respectively. We deemed the enzyme would be a member of laccase from its broad substrate specificity. However, typical laccase and other multi-copper oxidases such as bilirubin oxidase and ascorbate oxidase seldom exhibit urate oxidation activity. These results would expand the laccase substrate range to include urate.

  M. A Hossain , R Nakano , K Nakamura , M. T Hossain and Y. Kimura
 

It has been reported that acidic -mannosidase activity increases during tomato fruit ripening, suggesting the turnover of N-glycoproteins is deeply associated with fruit ripening. As part of a study to reveal the relationship between the plant -mannosidase activity and fruit maturation at the molecular level, we have already purified and characterized an -mannosidase from tomato fruit (Hossain et al., Biosci. Biotechnol. Biochem. 2009;73:140–146). In this article, we describe the identification and expression of the tomato acidic -mannosidase gene using the yeast-expression system. The -mannosidase-gene located at chomosome 6 is a 10 kb spanned containing 30 exons. The gene-encoded-protein is single polypeptide chain of 1,028 amino acids containing glycosyl hydrolase domain-38 with predicted molecular mass of 116 kDa. The recombinant enzyme showed maximum activity at pH 5.5, and was almost completely inhibited by both of 1-deoxymannojirimycin and swainsonine. The recombinant -mannosidase, like the native enzyme, could cleave 1-2, 1-3 and 1-6 mannosidic linkage from both high-mannose and truncated complex-type N-glycans. A molecular 3D modelling shows that catalytically important residues of animal lysosomal -mannosidase could be superimposed on those of tomato -mannosidase, suggesting that active site conformation is highly conserved between plant acidic -mannosidase and animal lysosomal -mannosidase.

 
 
 
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