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1.  Tetrahydrobiopterin Has a Glucose-Lowering Effect by Suppressing Hepatic Gluconeogenesis in an Endothelial Nitric Oxide Synthase–Dependent Manner in Diabetic Mice 
Diabetes  2013;62(9):3033-3043.
Endothelial nitric oxide synthase (eNOS) dysfunction induces insulin resistance and glucose intolerance. Tetrahydrobiopterin (BH4) is an essential cofactor of eNOS that regulates eNOS activity. In the diabetic state, BH4 is oxidized to 7,8-dihydrobiopterin, which leads to eNOS dysfunction owing to eNOS uncoupling. The current study investigates the effects of BH4 on glucose metabolism and insulin sensitivity in diabetic mice. Single administration of BH4 lowered fasting blood glucose levels in wild-type mice with streptozotocin (STZ)-induced diabetes and alleviated eNOS dysfunction by increasing eNOS dimerization in the liver of these mice. Liver has a critical role in glucose-lowering effects of BH4 through suppression of hepatic gluconeogenesis. BH4 activated AMP kinase (AMPK), and the suppressing effect of BH4 on gluconeogenesis was AMPK-dependent. In addition, the glucose-lowering effect and activation of AMPK by BH4 did not appear in mice with STZ-induced diabetes lacking eNOS. Consecutive administration of BH4 in ob/ob mice ameliorated glucose intolerance and insulin resistance. Taken together, BH4 suppresses hepatic gluconeogenesis in an eNOS-dependent manner, and BH4 has a glucose-lowering effect as well as an insulin-sensitizing effect in diabetic mice. BH4 has potential in the treatment of type 2 diabetes.
doi:10.2337/db12-1242
PMCID: PMC3749361  PMID: 23649519
2.  Moesin and Stress-Induced Phosphoprotein-1 Are Possible Sero-Diagnostic Markers of Psoriasis 
PLoS ONE  2014;9(7):e101773.
To identify diagnostic markers for psoriasis vulgaris and psoriatic arthritis, autoantibodies in sera from psoriasis vulgaris and psoriatic arthritis patients were screened by two-dimensional immunoblotting (2D-IB). Based on 2D-IB and MADLI TOF/TOF-MS analyses, eleven proteins each in psoriasis vulgaris and psoriatic arthritis were identified as autoantigens. Furthermore, serum levels of moesin, keratin 17 (K17), annexin A1 (ANXA1), and stress-induced phophoprotein-1 (STIP1), which were detected as autoantigens, were studied by dot blot analysis with psoriasis patients and healthy controls. The levels of moesin and STIP1 were significantly higher in sera from patients with psoriasis vulgaris than in the controls (moesin: P<0.05, STIP1: P<0.005). The area under the curve (AUC) for moesin and STIP1 between patients with psoraisis vulgaris and controls was 0.747 and 0.792, respectively. STIP1 and K17 levels were significantly higher in sera from patients with psoriatic arthritis than in those with psoriasis vulgaris (P<0.05 each). The AUC for STIP1 and K17 between patients with psoriatic arthritis and psoriasis vulgaris was 0.69 and 0.72, respectively. The STIP1 or moesin, CK17 serum level was not correlated with disease activity of psoriasis patients. These data suggest that STIP1 and moesin may be novel and differential sero-diagnostic markers for psoriasis vulgaris and psoriatic arthritis.
doi:10.1371/journal.pone.0101773
PMCID: PMC4092060  PMID: 25010044
3.  Reduction of Reactive Oxygen Species Ameliorates Metabolism-Secretion Coupling in Islets of Diabetic GK Rats by Suppressing Lactate Overproduction 
Diabetes  2013;62(6):1996-2003.
We previously demonstrated that impaired glucose-induced insulin secretion (IS) and ATP elevation in islets of Goto-Kakizaki (GK) rats, a nonobese model of diabetes, were significantly restored by 30–60-min suppression of endogenous reactive oxygen species (ROS) overproduction. In this study, we investigated the effect of a longer (12 h) suppression of ROS on metabolism-secretion coupling in β-cells by exposure to tempol, a superoxide (O2−) dismutase mimic, plus ebselen, a glutathione peroxidase mimic (TE treatment). In GK islets, both H2O2 and O2− were sufficiently reduced and glucose-induced IS and ATP elevation were improved by TE treatment. Glucose oxidation, an indicator of Krebs cycle velocity, also was improved by TE treatment at high glucose, whereas glucokinase activity, which determines glycolytic velocity, was not affected. Lactate production was markedly increased in GK islets, and TE treatment reduced lactate production and protein expression of lactate dehydrogenase and hypoxia-inducible factor 1α (HIF1α). These results indicate that the Warburg-like effect, which is characteristic of aerobic metabolism in cancer cells by which lactate is overproduced with reduced linking to mitochondria metabolism, plays an important role in impaired metabolism-secretion coupling in diabetic β-cells and suggest that ROS reduction can improve mitochondrial metabolism by suppressing lactate overproduction through the inhibition of HIF1α stabilization.
doi:10.2337/db12-0903
PMCID: PMC3661648  PMID: 23349483
4.  Nestin Is an Independent Predictor of Cancer-Specific Survival after Radical Cystectomy in Patients with Urothelial Carcinoma of the Bladder 
PLoS ONE  2014;9(5):e91548.
Objectives
To investigate the association between the expression of nestin, a class VI intermediate filament protein, and pathologic features or survival in patients with urothelial carcinoma of the bladder (UCB).
Methods
Nestin expression in tumor cells was immunohistochemically studied in 93 patients with UCB who underwent radical cystectomy with pelvic lymphadenectomy. The associations with clinicopathologic parameters were evaluated. Kaplan–Meier survival analysis and Cox proportional hazards models were used to estimate the effect of nestin expression on survival.
Results
Nestin expression in cystectomy specimens was observed in 13 of 93 patients (14.0%). Nestin expression was associated with pathologic tumor stage (p = 0.006). Nestin-negative patients had better overall survival compared with nestin-positive patients (log-rank p = 0.0148). Univariable analysis indicated that nestin expression, lymphovascular invasion, and lymph node status were significantly associated with cancer-specific survival (hazard ratios, 2.78, 2.15, and 2.80, respectively). On multivariable analysis, nestin expression and lymph node status were independent prognostic factors in cancer-specific survival (hazard ratios, 2.45 and 2.65, respectively).
Conclusions
The results suggest that nestin expression is a novel independent prognostic indicator for patients with UCB and a potentially useful marker to select patients who may be candidates for adjuvant chemotherapy.
doi:10.1371/journal.pone.0091548
PMCID: PMC4008365  PMID: 24785714
5.  Palmitate induces reactive oxygen species production and β‐cell dysfunction by activating nicotinamide adenine dinucleotide phosphate oxidase through Src signaling 
Abstract
Aims/Introduction
Chronic hyperlipidemia impairs pancreatic β‐cell function, referred to as lipotoxicity. We have reported an important role of endogenous reactive oxygen species (ROS) overproduction by activation of Src, a non‐receptor tyrosine kinase, in impaired glucose‐induced insulin secretion (GIIS) from diabetic rat islets. In the present study, we investigated the role of ROS production by Src signaling in palmitate‐induced dysfunction of β‐cells.
Materials and Methods
After rat insulinoma INS‐1D cells were exposed to 0.6 mmol/L palmitate for 24 h (palmitate exposure); GIIS, ROS production and nicotinamide adenine dinucleotide phosphate oxidase (NOX) activity were examined with or without exposure to10 μmol/L 4‐amino‐5‐(4‐chlorophenyl)‐7‐(t‐butyl)pyrazolo[3,4‐d]pyrimidine (PP2), a Src inhibitior, for 30 or 60 min.
Results
Exposure to PP2 recovered impaired GIIS and decreased ROS overproduction as a result of palmitate exposure. Palmitate exposure increased activity of NOX and protein levels of NOX2, a pathological ROS source in β‐cells. Palmitate exposure increased the protein level of p47phox, a regulatory protein of NOX2, in membrane fraction compared with control, which was reduced by PP2. Transfection of small interfering ribonucleic acid of p47phox suppressed the augmented p47phox protein level in membrane fraction, decreased augmented ROS production and increased impaired GΙIS by palmitate exposure. In addition, exposure to PP2 ameliorated impaired GIIS and decreased ROS production in isolated islets of KK‐Ay mice, an obese diabetic model with hyperlipidemia.
Conclusions
Activation of NOX through Src signaling plays an important role in ROS overproduction and impaired GΙIS caused by chronic exposure to palmitate, suggesting a lipotoxic mechanism of β‐cell dysfunction of obese mice.
doi:10.1111/jdi.12124
PMCID: PMC4025235  PMID: 24843732
Lipotoxicity; Pancreatic β‐cells; Reactive oxygen species
6.  Diversity of DNA damage response of astrocytes and glioblastoma cell lines with various p53 status to treatment with etoposide and temozolomide 
Cancer biology & therapy  2009;8(5):452-457.
Phpsphorylation of histone H2AX is a sensitive marker of DNA damage, particularly of DNA double strand breaks. Using multiparameter cytometry we explored effects of etoposide and temozolomide (TMZ) on three glioblastoma cell lines with different p53 status (A172, T98G, YKG-1) and on normal human astrocytes (NHA) correlating the drug-induced phosphorylated H2AX (γH2AX) with cell cycle phase and induction of apoptosis. Etoposide induced γH2AX in all phases of the cell cycle in all three glioblastoma lines and led to an arrest of T98G and YKG-1 cells in S and G2/M. NHA cells were arrested in G1 with no evidence of γH2AX induction. A172 responded by rise in γH2AX throughout all phases of the cycle, arrest at the late S- to G2/M-phase, and appearance of senescence features: induction of p53, p21WAF1/CIP1, p16INK4A and β-galactosidase, accompanied by morphological changes typical of senescence. T98G cells showed the presence of γH2AX in S phase with no evidence of cell cycle arrest. A modest degree of arrest in G1 was seen in YKG-1 cells with no rise in γH2AX. While frequency of apoptotic cells in all four TMZ-treated cell cultures was relatively low it is conceivable that the cells with extensive DNA damage were reproductively dead. The data show that neither the status of p53 (wild-type vs. mutated, or inhibited by pifithrin-α) nor the expression of O6-methylguanine-DNA methyltransferase significantly affected the cell response to TMZ. Because of diversity in response to TMZ between individual glioblastoma lines our data suggest that with better understanding of the mechanisms, the treatment may have to be customized to individual patients.
PMCID: PMC3855308  PMID: 19305157
glioblastoma; temozolomide; etoposide; DNA double strand break; DNA damage; senescence; cell cycle
7.  Conformational changes of the phenyl and naphthyl isocyanate-DNA adducts during DNA replication and by minor groove binding molecules 
Nucleic Acids Research  2013;41(18):8581-8590.
DNA lesions produced by aromatic isocyanates have an extra bulky group on the nucleotide bases, with the capability of forming stacking interaction within a DNA helix. In this work, we investigated the conformation of the 2′-deoxyadenosine and 2′-deoxycytidine derivatives tethering a phenyl or naphthyl group, introduced in a DNA duplex. The chemical modification experiments using KMnO4 and 1-cyclohexyl-3 -(2-morpholinoethyl) carbodiimide metho-p-toluenesulfonate have shown that the 2′-deoxycytidine lesions form the base pair with guanine while the 2′-deoxyadenosine lesions have less ability of forming the base pair with thymine in solution. Nevertheless, the kinetic analysis shows that these DNA lesions are compatible with DNA ligase and DNA polymerase reactions, as much as natural DNA bases. We suggest that the adduct lesions have a capability of adopting dual conformations, depending on the difference in their interaction energies between stacking of the attached aromatic group and base pairing through hydrogen bonds. It is also presented that the attached aromatic groups change their orientation by interacting with the minor groove binding netropsin, distamycin and synthetic polyamide. The nucleotide derivatives would be useful for enhancing the phenotypic diversity of DNA molecules and for exploring new non-natural nucleotides.
doi:10.1093/nar/gkt608
PMCID: PMC3794578  PMID: 23873956
8.  Quantifying longitudinal right ventricular dysfunction in patients with old myocardial infarction by using speckle-tracking strain echocardiography 
Background
We investigated longitudinal right ventricular (RV) function assessed using speckle-tracking strain echocardiography in patient with myocardial infarction (MI), and identified the contributing factors for RV dysfunction.
Methods
We retrospectively studied 71 patients with old MI (the OMI group) and 45 normal subjects (the Control group) who underwent a transthoracic echocardiography. Global and free wall RV peak systolic strains (PSSs) in the longitudinal direction were measured by using speckle-tracking strain echocardiography. Left ventricular (LV) PSSs were measured in the longitudinal, radial and circumferential directions. Cardiac hemodynamics including peak systolic pulmonary artery pressure was also assessed non-invasively. Plasma brain natriuretic peptide (BNP) levels were measured in all patients.
Results
In the OMI group, 73% of the patients had a normal estimated peak systolic pulmonary artery pressure of less than 35 mmHg. Global and free wall RV PSS were impaired in the OMI group compared with the Control group, and these RV systolic indices were significantly associated with heart rate, logarithmic transformed plasma BNP, greater than 1 year after onset of MI, Doppler-derived estimated pulmonary vascular resistance, LV systolic indices, LV mass index, infarcted segments within a territory of the left circumflex artery and residual total occlusion in the culprit right coronary artery. Multivariable linear regression analysis indicated that reduced longitudinal LV PSS in the 4-chamber view and BNP levels ≥500 pg/ml were independently associated with reduced global and free wall RV PSS. Moreover, when patients were divided into 3 groups according to plasma BNP levels (BNP <100 pg/ml; n = 31, 100 ≤BNP <500 pg/ml; n = 24, and BNP ≥500 pg/ml; n = 16), only patients with BNP ≥500 pg/ml had a strong correlation between RV PSS and longitudinal LV PSS in the 4-chamber view (r = 0.78 for global RV PSS and r = 0.71 for free wall RV PSS, p <0.05).
Conclusion
Longitudinal RV systolic strain depends significantly on longitudinal LV systolic strain especially in patients with high plasma BNP levels, but not on estimated peak systolic pulmonary artery pressure. These results indicate that process of RV myocardial dysfunction following MI may be governed by neurohormonal activation which causing ventricular remodeling rather than increased RV afterload.
doi:10.1186/1476-7120-11-23
PMCID: PMC3700756  PMID: 23802850
Echocardiography; Right Ventricle; Myocardial Infarction; Plasma Brain Natriuretic Peptide
9.  Abnormal expression of multiple proteins predicts cancer-specific mortality in patients with high-grade non-muscle-invasive bladder cancer treated with transurethral resection 
Molecular and Clinical Oncology  2013;1(3):473-479.
High-grade non-muscle-invasive bladder urothelial carcinoma leads to various outcomes. It can cause death even after radical cystectomy and is treated only by transurethral resection (TUR). In the present study, we aimed to determine whether the molecular markers E-cadherin, coxsackie adenovirus receptor (CAR), S100A4 and uroplakin III are associated with clinicopathological outcomes in patients with high-grade non-muscle invasive bladder cancer (NMIBC) treated with TUR. Immunohistochemical staining was performed on serial sections from specimens obtained from 77 patients. Expression patterns were stratified according to the number of abnormally expressed markers: 0–1 or ≥2. The median follow-up time was 56 months (range, 3–287). The results from the present study indicated that expression of E-cadherin, CAR, S100A4 and uroplakin III was abnormal in 16, 17, 27 and 61% of tumors, respectively. Results of the log-rank test revealed that patients with abnormal expression of multiple molecular markers had a significantly increased risk of bladder cancer-specific mortality (P=0.016). The 5-year cancer-specific survival rates were 91 and 66% for patients with 0–1 and ≥2 molecular markers, respectively. No individual marker was associated with disease prognosis. Multivariate models that included clinicopathological outcomes and classified molecular markers indicated that abnormal expression of multiple molecular markers and lack of bacillus Calmette-Guérin (BCG) instillation are predictors of cancer-specific death (P=0.046 and 0.029, respectively). Abnormal expression of multiple molecular markers is a strong predictor of mortality in bladder cancer patients undergoing TUR, suggesting that high-grade non-muscle-invasive cancer is characterized by a variety of pathophysiological pathways. A combination of molecular markers may be useful in a minimally invasive modality for determining prognosis.
doi:10.3892/mco.2013.92
PMCID: PMC3915659  PMID: 24649194
bladder cancer; high-grade; non-muscle-invasive bladder cancer; survival; immunohistochemistry
10.  Clinicopathological features and the impact of the new TNM classification of malignant tumors in patients with pulmonary large cell neuroendocrine carcinoma 
Molecular and Clinical Oncology  2013;1(3):437-443.
The prognosis of patients with large-cell neuroendocrine carcinoma (LCNEC) of the lung is extremely poor and the optimal treatment for these patients has yet to be determined. In this study, we described the clinicopathological characteristics of LCNECs and compared the prognoses of corresponding stages determined by the guidelines of the 6th and 7th editions of the TNM classification of malignant tumors. Clinical data from 42 patients diagnosed with primary LCNEC who underwent treatment at Kitasato University Hospital between 1991 and 2009 were retrospectively analyzed. On follow-up of 42 patients, 22 (52.4%) had confirmed recurrent tumors, including 8 patients with mediastinal lymph node recurrences and 19 with distant metastases. The sites of distant metastases included the brain in 8, bone in 8, liver in 7, lungs in 5 and adrenal glands in 4 patients. For all the patients, the 5-year overall survival rate was 34.7% and the 5-year disease-free survival rate was 32.9%. The 5-year overall survival rates of patients with stage I cancers according to the 6th and 7th staging editions was 51.3% (6th n=18, 7th n=16). Thirteen of 42 patients (31.0%) also had metachronous or synchronous primary cancers. Patients with LCNEC had poor outcomes, even those with stage I tumors classified according to the 7th edition of the TNM classification. Therefore, frequent recurrences in addition to metachronous or synchronous primary cancers in patients with LCNEC should be treated.
doi:10.3892/mco.2013.80
PMCID: PMC3916090  PMID: 24649189
large cell; neuroendocrine; TNM stage; prognosis; outcome
11.  Distant Metastasis from Benign Solitary Fibrous Tumor of the Kidney 
Solitary fibrous tumor (SFT) rarely occurs in the kidneys, and only one reported case of renal SFT has shown distant metastasis. We report the second case of renal SFT exhibiting distant metastasis. A 48-year-old man was referred to our hospital because of a right renal mass. An abdominal CT scan detected a large renal tumor, which was suspected to be a renal cell carcinoma. Right radical nephrectomy was performed, and the tumor was found to measure 28 × 18 × 10 cm. The pathological diagnosis was benign solitary fibrous tumor of the kidney. Eight years after the operation, lung and liver metastases developed. Pulmonary segmentectomy and partial hepatectomy were performed. The pathological diagnoses of these resected tissue specimens were compatible with benign SFT.
doi:10.1159/000346850
PMCID: PMC3573797  PMID: 23466873
Solitary fibrous tumor; Metastasis; Kidney; Malignant; CD34
12.  A giant prostatic hyperplasia treated by open surgery 
We report a rare case of giant prostatic hyperplasia treated by open surgery. A 70-year-old man was suffering from macrohematuria. Computed tomography revealed a markedly enlarged prostate measuring 580 mL. The serum prostate-specific antigen level was 9.430 ng/mL. Prostatic biopsy showed benign prostatic hyperplasia. We perfomed retropubic open prostatectomy, since macrohematuria continued and he was also suffering from lower urinary tract symptoms. The adenoma was completely enucleated in one piece. The removed specimen was 13 × 11 × 6 cm in size and weighed 475 g. Histological examination also demonstrated prostatic fibromuscular hyperplasia. This is the 15th-heaviest adenoma ever reported in English-language journals. Transurethral surgical techniques or other minimally invasive approaches are performed for patients with small to medium-sized prostates. However, open surgery is recommended for markedly enlarged prostatic hyperplasia.
doi:10.2147/IJGM.S38238
PMCID: PMC3526873  PMID: 23271919
benign prostatic enlargement; benign prostatic hyperplasia; giant; retropubic open prostatectomy
13.  Behavior and Distribution of Heavy Metals Including Rare Earth Elements, Thorium, and Uranium in Sludge from Industry Water Treatment Plant and Recovery Method of Metals by Biosurfactants Application 
In order to investigate the behavior, distribution, and characteristics of heavy metals including rare earth elements (REEs), thorium (Th), and uranium (U) in sludge, the total and fractional concentrations of these elements in sludge collected from an industry water treatment plant were determined and compared with those in natural soil. In addition, the removal/recovery process of heavy metals (Pb, Cr, and Ni) from the polluted sludge was studied with biosurfactant (saponin and sophorolipid) elution by batch and column experiments to evaluate the efficiency of biosurfactant for the removal of heavy metals. Consequently, the following matters have been largely clarified. (1) Heavy metallic elements in sludge have generally larger concentrations and exist as more unstable fraction than those in natural soil. (2) Nonionic saponin including carboxyl group is more efficient than sophorolipid for the removal of heavy metals in polluted sludge. Saponin has selectivity for the mobilization of heavy metals and mainly reacts with heavy metals in F3 (the fraction bound to carbonates) and F5 (the fraction bound to Fe-Mn oxides). (3) The recovery efficiency of heavy metals (Pb, Ni, and Cr) reached about 90–100% using a precipitation method with alkaline solution.
doi:10.1155/2012/173819
PMCID: PMC3368164  PMID: 22693485
14.  CAXII Is a Sero-Diagnostic Marker for Lung Cancer 
PLoS ONE  2012;7(3):e33952.
To develop sero-diagnostic markers for lung cancer, we generated monoclonal antibodies using pulmonary adenocarcinoma (AD)-derived A549 cells as antigens by employing the random immunization method. Hybridoma supernatants were immunohistochemically screened for antibodies with AMeX-fixed and paraffin-embedded A549 cell preparations. Positive clones were monocloned twice through limiting dilutions. From the obtained monoclonal antibodies, we selected an antibody designated as KU-Lu-5 which showed intense membrane staining of A549 cells. Based on immunoprecipitation and MADLI TOF/TOF-MS analysis, this antibody was recognized as carbonic anhydrase XII (CAXII). To evaluate the utility of this antibody as a sero-diagnostic marker for lung cancer, we performed dot blot analysis with a training set consisting of sera from 70 lung cancer patients and 30 healthy controls. The CAXII expression levels were significantly higher in lung cancer patients than in healthy controls in the training set (P<0.0001), and the area under the curve of ROC was 0.794, with 70.0% specificity and 82.9% sensitivity. In lung cancers, expression levels of CAXII were significantly higher in patients with squamous cell carcinoma (SCC) than with AD (P = 0.035). Furthermore, CAXII was significantly higher in well- and moderately differentiated SCCs than in poorly differentiated ones (P = 0.027). To further confirm the utility of serum CAXII levels as a sero-diagnostic marker, an additional set consisting of sera from 26 lung cancer patients and 30 healthy controls was also investigated by dot blot analysis as a validation study. Serum CAXII levels were also significantly higher in lung cancer patients than in healthy controls in the validation set (P = 0.030). Thus, the serum CAXII levels should be applicable markers discriminating lung cancer patients from healthy controls. To our knowledge, this is the first report providing evidence that CAXII may be a novel sero-diagnostic marker for lung cancer.
doi:10.1371/journal.pone.0033952
PMCID: PMC3306309  PMID: 22439015
15.  Exendin-4 Suppresses Src Activation and Reactive Oxygen Species Production in Diabetic Goto-Kakizaki Rat Islets in an Epac-Dependent Manner 
Diabetes  2010;60(1):218-226.
OBJECTIVE
Reactive oxygen species (ROS) is one of most important factors in impaired metabolism secretion coupling in pancreatic β-cells. We recently reported that elevated ROS production and impaired ATP production at high glucose in diabetic Goto-Kakizaki (GK) rat islets are effectively ameliorated by Src inhibition, suggesting that Src activity is upregulated. In the present study, we investigated whether the glucagon-like peptide-1 signal regulates Src activity and ameliorates endogenous ROS production and ATP production in GK islets using exendin-4.
RESEARCH DESIGN AND METHODS
Isolated islets from GK and control Wistar rats were used for immunoblotting analyses and measurements of ROS production and ATP content. Src activity was examined by immunoprecipitation of islet lysates followed by immunoblotting. ROS production was measured with a fluorescent probe using dispersed islet cells.
RESULTS
Exendin-4 significantly decreased phosphorylation of Src Tyr416, which indicates Src activation, in GK islets under 16.7 mmol/l glucose exposure. Glucose-induced ROS production (16.7 mmol/l) in GK islet cells was significantly decreased by coexposure of exendin-4 as well as PP2, a Src inhibitor. The Src kinase–negative mutant expression in GK islets significantly decreased ROS production induced by high glucose. Exendin-4, as well as PP2, significantly increased impaired ATP elevation by high glucose in GK islets. The decrease in ROS production by exendin-4 was not affected by H-89, a PKA inhibitor, and an Epac-specific cAMP analog (8CPT-2Me-cAMP) significantly decreased Src Tyr416 phosphorylation and ROS production.
CONCLUSIONS
Exendin-4 decreases endogenous ROS production and increases ATP production in diabetic GK rat islets through suppression of Src activation, dependently on Epac.
doi:10.2337/db10-0021
PMCID: PMC3012174  PMID: 20978090
16.  Expression profiling and identification of potential molecular targets for therapy in pulmonary large-cell neuroendocrine carcinoma 
The prognosis for patients with large-cell neuroendocrine carcinoma (LCNEC) of the lung is extremely poor, and an optimal treatment has not yet been established. It has been recently reported that molecular-targeted therapies, such as tyrosine kinase inhibitors for epidermal growth factor receptor (EGFR), are effective in patients with lung carcinoma. In efforts to improve the prognosis of patients with LCNEC, we analyzed gene expression, gene mutations and immunohistochemical (IHC) expression of known molecular targets in LCNECs, and compared the expression to that of lung adenocarcinomas (ACs). Thirteen patients with primary LCNEC and 14 patients with AC were analyzed. We evaluated IHC expression for c-KIT, human epidermal growth factor receptor type 2 (HER2) and vascular endothelial growth factor (VEGF), gene mutations for EGFR, K-ras and c-kit, and gene expression using fluorescence in situ hybridization for EGFR. In cases with LCNEC, the IHC expression of c-KIT, HER2 and VEGF was 76.9, 30.8 and 100%, respectively. There was a significant difference in the IHC expression of c-KIT and HER2 between the LCNEC and AC cases. Two cases of LCNEC had overexpression of HER2, and the frequency of EGFR gene mutations was higher in the the AC group, with only a single EGFR mutation (exon 18) identified in the LCNEC group. Although LCNEC had a higher rate of expression of c-KIT by IHC, no c-kit gene mutations were found. These findings suggest a potential role for anti-VEGF-, anti-c-KIT- and possibly anti-HER2-targeted agents in the treatment of LCNEC.
doi:10.3892/etm.2011.343
PMCID: PMC3440793  PMID: 22977617
large-cell neuroendocrine carcinoma; molecular-targeted therapy; vascular endothelial growth factor; c-KIT; human epidermal growth factor receptor type 2
17.  Properties and Crystal Structure of Methylenetetrahydrofolate Reductase from Thermus thermophilus HB8 
PLoS ONE  2011;6(8):e23716.
Background
Methylenetetrahydrofolate reductase (MTHFR) is one of the enzymes involved in homocysteine metabolism. Despite considerable genetic and clinical attention, the reaction mechanism and regulation of this enzyme are not fully understood because of difficult production and poor stability. While recombinant enzymes from thermophilic organisms are often stable and easy to prepare, properties of thermostable MTHFRs have not yet been reported.
Methodology/Principal Findings
MTHFR from Thermus thermophilus HB8, a homologue of Escherichia coli MetF, has been expressed in E. coli and purified. The purified MTHFR was chiefly obtained as a heterodimer of apo- and holo-subunits, that is, one flavin adenine dinucleotide (FAD) prosthetic group bound per dimer. The crystal structure of the holo-subunit was quite similar to the β8α8 barrel of E. coli MTHFR, while that of the apo-subunit was a previously unobserved closed form. In addition, the intersubunit interface of the dimer in the crystals was different from any of the subunit interfaces of the tetramer of E. coli MTHFR. Free FAD could be incorporated into the apo-subunit of the purified Thermus enzyme after purification, forming a homodimer of holo-subunits. Comparison of the crystal structures of the heterodimer and the homodimer revealed different intersubunit interfaces, indicating a large conformational change upon FAD binding. Most of the biochemical properties of the heterodimer and the homodimer were the same, except that the homodimer showed ≈50% activity per FAD-bound subunit in folate-dependent reactions.
Conclusions/Significance
The different intersubunit interfaces and rearrangement of subunits of Thermus MTHFR may be related to human enzyme properties, such as the allosteric regulation by S-adenosylmethionine and the enhanced instability of the Ala222Val mutant upon loss of FAD. Whereas E. coli MTHFR was the only structural model for human MTHFR to date, our findings suggest that Thermus MTHFR will be another useful model for this important enzyme.
doi:10.1371/journal.pone.0023716
PMCID: PMC3156243  PMID: 21858212
20.  Crystal Structures of the Lumazine Protein from Photobacterium kishitanii in Complexes with the Authentic Chromophore, 6,7-Dimethyl- 8-(1′-d-Ribityl) Lumazine, and Its Analogues, Riboflavin and Flavin Mononucleotide, at High Resolution▿  
Journal of Bacteriology  2009;192(1):127-133.
Lumazine protein (LumP) is a fluorescent accessory protein having 6,7-dimethyl-8-(1′-d-ribityl) lumazine (DMRL) as its authentic chromophore. It modulates the emission of bacterial luciferase to shorter wavelengths with increasing luminous strength. To obtain structural information on the native structure as well as the interaction with bacterial luciferase, we have determined the crystal structures of LumP from Photobacterium kishitanii in complexes with DMRL and its analogues, riboflavin (RBF) and flavin mononucleotide (FMN), at resolutions of 2.00, 1.42, and 2.00 Å. LumP consists of two β barrels that have nearly identical folds, the N-terminal and C-terminal barrels. The structures of LumP in complex with all of the chromophores studied are all essentially identical, except around the chromophores. In all of the structures, the chromophore is tethered to the narrow cavity via many hydrogen bonds in the N-terminal domain. These are absent in the C-terminal domain. Hydrogen bonding in LumP-FMN is decreased in comparison with that in LumP-RBF because the phosphate moiety of FMN protrudes out of the narrow cavity. In LumP-DMRL, the side chain of Gln65 is close to the ring system, and a new water molecule that stabilizes the ligand is observed near Ser48. Therefore, DMRL packs more tightly in the ligand-binding site than RBF or FMN. A docking simulation of bacterial luciferase and LumP suggests that the chromophore is located close enough for direct energy transfer to occur. Moreover, the surface potentials around the ligand-binding sites of LumP and bacterial luciferase exhibit complementary charge distributions, which would have a significant effect on the interaction between LumP and luciferase.
doi:10.1128/JB.01015-09
PMCID: PMC2798275  PMID: 19854891
21.  Cardiac scintigraphic findings of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes: A case report 
A 49-year-old woman was admitted to hospital because of heart failure. She was diagnosed as having mitochondrial cardiomyopathy and diabetes mellitus. Echocardiography revealed a hypertrophic and poorly contracting left ventricle. A diagnosis of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes was established by muscle biopsy. She underwent technetium-99m-sestamibi (99mTc-MIBI) and beta-methyl-p-123I-iodophenyl-pentadecanoic acid (123I-BMIPP) scintigraphic examinations. 99mTc-MIBI single-photon emission computed tomography revealed reduced tracer uptake in the hypertrophic left ventricular inferior wall. In contrast, there was an increase in 123I-BMIPP uptake in the in the region of reduced 99mTc-MIBI uptake (99mTc-MIBI/123I-BMIPP mismatch). There was rapid washout of 99mTc-MIBI from the myocardium (washout rate increased by 30%). Decreased 99mTc-MIBI and increased 123I-BMIPP uptake (99mTc-MIBI/123I-BMIPP mismatch) were the characteristics of cardiac involvement in mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes.
PMCID: PMC2586404  PMID: 19343124
99mTc-MIBI; 123I-BMIPP mismatch; 99mTc-MIBI washout; MELAS
22.  Mid-Ventricular Obstructive Hypertrophic Cardiomyopathy Associated with an Apical Aneurysm: Evaluation of Possible Causes of Aneurysm Formation 
Yonsei Medical Journal  2007;48(5):879-882.
Mid-ventricular obstructive hypertrophic cardiomyopathy (MVOHCM) is a rare type of cardiomyopathy, associated with apical aneurysm formation in some cases. We report a patient presenting with ventricular fibrillation, an ECG with an above normal ST segment, and elevated levels of cardiac enzymes but normal coronary arteries. Left ventriculography revealed a left ventricular obstruction without apical aneurysm. There was a significant pressure gradient between the apical and basal sites of the left ventricle. Cine magnetic resonance imaging (MRI), performed on the 10th hospital day, showed asymmetric septal hypertrophy, mid-ventricular obstruction, and an apical aneurysm with a thrombus. The first evaluation by contrast-enhanced imaging showed a subendocardial perfusion defect and delayed enhancement. It was speculated that the intraventricular pressure gradient, due to mid-ventricular obstruction, triggered myocardial infarction, which subsequently resulted in apical aneurysm formation.
doi:10.3349/ymj.2007.48.5.879
PMCID: PMC2628158  PMID: 17963350
Mid-ventricular obstructive hypertrophic cardiomyopathy; magnetic resonance imaging
23.  Mid-Ventricular Hypertrophic Obstructive Cardiomyopathy Presenting with Acute Myocardial Infarction 
Texas Heart Institute Journal  2007;34(4):475-478.
Mid-ventricular hypertrophic obstructive cardiomyopathy is a rare type of cardiomyopathy that can be accompanied by apical aneurysm. We report the case of a patient who presented with ventricular fibrillation, ST-segment elevation on electrocardiography, and cardiac-enzyme elevation, in the presence of normal coronary arteries. Echocardiography and magnetic resonance imaging showed an hourglass appearance of the left ventricle with an aneurysm in the apex. Left-heart catheterization and continuous-wave Doppler echocardiography revealed a pressure gradient between the apical and basal chambers of the left ventricle. Impaired coronary artery circulation might play a role in the development of mid-ventricular obstruction in patients with mid-ventricular hypertrophic obstructive cardiomyopathy.
PMCID: PMC2170479  PMID: 18172535
Cardiomyopathy, hypertrophic/complications/physiopathology; heart aneurysm/etiology; magnetic resonance imaging; myocardial infarction; thallium radioisotopes/diagnostic use; tomography, emission computed, single-photon; ventricular outflow obstruction/diagnosis

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