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Sample records for oxidatively modified dna

  1. Graphene electrode modified with electrochemically reduced graphene oxide for label-free DNA detection.

    Li, Bing; Pan, Genhua; Avent, Neil D; Lowry, Roy B; Madgett, Tracey E; Waines, Paul L

    2015-10-15

    A novel printed graphene electrode modified with electrochemically reduced graphene oxide was developed for the detection of a specific oligonucleotide sequence. The graphene oxide was immobilized onto the surface of a graphene electrode via π-π bonds and electrochemical reduction of graphene oxide was achieved by cyclic voltammetry. A much higher redox current was observed from the reduced graphene oxide-graphene double-layer electrode, a 42% and 36.7% increase, respectively, in comparison with that of a bare printed graphene or reduced graphene oxide electrode. The good electron transfer activity is attributed to a combination of the large number of electroactive sites in reduced graphene oxide and the high conductivity nature of graphene. The probe ssDNA was further immobilized onto the surface of the reduced graphene oxide-graphene double-layer electrode via π-π bonds and then hybridized with its target cDNA. The change of peak current due to the hybridized dsDNA could be used for quantitative sensing of DNA concentration. It has been demonstrated that a linear range from 10(-7)M to 10(-12)M is achievable for the detection of human immunodeficiency virus 1 gene with a detection limit of 1.58 × 10(-13)M as determined by three times standard deviation of zero DNA concentration. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. [Endonuclease modified comet assay for oxidative DNA damage induced by detection of genetic toxicants].

    Zhao, Jian; Li, Hongli; Zhai, Qingfeng; Qiu, Yugang; Niu, Yong; Dai, Yufei; Zheng, Yuxin; Duan, Huawei

    2014-03-01

    The aim of this study was to investigate the use of the lesion-specific endonucleases-modified comet assay for analysis of DNA oxidation in cell lines. DNA breaks and oxidative damage were evaluated by normal alkaline and formamidopyrimidine-DNA-glycosylase (FPG) modified comet assays. Cytotoxicity were assessed by MTT method. The human bronchial epithelial cell (16HBE) were treated with benzo (a) pyrene (B(a)P), methyl methanesulfonate (MMS), colchicine (COL) and vincristine (VCR) respectively, and the dose is 20 µmol/L, 25 mg/ml, 5 mg/L and 0.5 mg/L for 24 h, respectively. Oxidative damage was also detected by levels of reactive oxygen species in treated cells. Four genotoxicants give higher cytotoxicity and no significant changes on parameters of comet assay treated by enzyme buffer. Cell survival rate were (59.69 ± 2.60) %, (54.33 ± 2.81) %, (53.11 ± 4.00) %, (51.43 ± 3.92) % in four groups, respectively. There was the direct DNA damage induced by test genotoxicants presented by tail length, Olive tail moment (TM) and tail DNA (%) in the comet assay. The presence of FPG in the assays increased DNA migration in treated groups when compared to those without it, and the difference was statistically significant which indicated that the clastogen and aneugen could induce oxidative damage in DNA strand. In the three parameters, the Olive TM was changed most obviously after genotoxicants treatment. In the contrast group, the Olive TM of B(a) P,MMS, COL,VCR in the contrast groups were 22.99 ± 17.33, 31.65 ± 18.86, 19.86 ± 9.56 and 17.02 ± 9.39, respectively, after dealing with the FPG, the Olive TM were 34.50 ± 17.29, 43.80 ± 10.06, 33.10 ± 12.38, 28.60 ± 10.53, increased by 58.94%, 38.48%, 66.86% and 68.21%, respectively (t value was 3.91, 3.89, 6.66 and 3.87, respectively, and all P comet assay appears more specific for detecting oxidative DNA damage induced by genotoxicants exposure, and the application of comet assay will be expanded. The endonuclease

  3. Label-free, electrochemical detection of methicillin-resistant staphylococcus aureus DNA with reduced graphene oxide-modified electrodes

    Wang, Zhijuan

    2011-05-01

    Reduced graphene oxide (rGO)-modified glassy carbon electrode is used to detect the methicillin-resistant Staphylococcus aureus (MRSA) DNA by using electrochemical impedance spectroscopy. Our experiments confirm that ssDNA, before and after hybridization with target DNA, are successfully anchored on the rGO surface. After the probe DNA, pre-adsorbed on rGO electrode, hybridizes with target DNA, the measured impedance increases dramatically. It provides a new method to detect DNA with high sensitivity (10-13M, i.e., 100 fM) and selectivity. © 2011 Elsevier B.V.

  4. Electrochemical label-free and sensitive nanobiosensing of DNA hybridization by graphene oxide modified pencil graphite electrode.

    Ahour, F; Shamsi, A

    2017-09-01

    Based on the strong interaction between single-stranded DNA (ss-DNA) and graphene material, we have constructed a novel label-free electrochemical biosensor for rapid and facile detection of short sequences ss-DNA molecules related to hepatitis C virus 1a using graphene oxide modified pencil graphite electrode. The sensing mechanism is based on the superior adsorption of single-stranded DNA to GO over double stranded DNA (ds-DNA). The intrinsic guanine oxidation signal measured by differential pulse voltammetry (DPV) has been used for duplex DNA formation detection. The probe ss-DNA adsorbs onto the surface of GO via the π- π* stacking interactions leading to a strong background guanine oxidation signal. In the presence of complementary target, formation of helix which has weak binding ability to GO induced ds-DNA to release from the electrode surface and significant variation in differential pulse voltammetric response of guanine bases. The results indicated that the oxidation peak current was proportional to the concentration of complementary strand in the range of 0.1 nM-0.5 μM with a detection limit of 4.3 × 10 -11  M. The simple fabricated electrochemical biosensor has high sensitivity, good selectivity, and could be applied as a new platform for a range of target molecules in future. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. The utilization of SiNWs/AuNPs-modified indium tin oxide (ITO) in fabrication of electrochemical DNA sensor.

    Rashid, Jahwarhar Izuan Abdul; Yusof, Nor Azah; Abdullah, Jaafar; Hashim, Uda; Hajian, Reza

    2014-12-01

    This work describes the incorporation of SiNWs/AuNPs composite as a sensing material for DNA detection on indium tin-oxide (ITO) coated glass slide. The morphology of SiNWs/AuNPs composite as the modifier layer on ITO was studied by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The morphological studies clearly showed that SiNWs were successfully decorated with 20 nm-AuNPs using self-assembly monolayer (SAM) technique. The effective surface area for SiNWs/AuNPs-modified ITO enhanced about 10 times compared with bare ITO electrode. SiNWs/AuNPs nanocomposite was further explored as a matrix for DNA probe immobilization in detection of dengue virus as a bio-sensing model to evaluate its performance in electrochemical sensors. The hybridization of complementary DNA was monitored by differential pulse voltammetry (DPV) using methylene blue (MB) as the redox indicator. The fabricated biosensor was able to discriminate significantly complementary, non-complementary and single-base mismatch oligonucleotides. The electrochemical biosensor was sensitive to target DNA related to dengue virus in the range of 9.0-178.0 ng/ml with detection limit of 3.5 ng/ml. In addition, SiNWs/AuNPs-modified ITO, regenerated up to 8 times and its stability was up to 10 weeks at 4°C in silica gel. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. The utilization of SiNWs/AuNPs-modified indium tin oxide (ITO) in fabrication of electrochemical DNA sensor

    Rashid, Jahwarhar Izuan Abdul [Institute of Advanced Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Department of Chemistry and Biology, Centre for Defense Foundation Studies, National Defense University of Malaysia, Sungai Besi Camp, 57000 Kuala Lumpur (Malaysia); Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Yusof, Nor Azah, E-mail: azahy@upm.edu.my [Institute of Advanced Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Abdullah, Jaafar [Institute of Advanced Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Hashim, Uda [Institute of Nanoelectronic Engineering, Universiti Malaysia Perlis, 01000 Kangar, Perlis (Malaysia); Hajian, Reza, E-mail: rezahajian@upm.edu.my [Institute of Advanced Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2014-12-01

    This work describes the incorporation of SiNWs/AuNPs composite as a sensing material for DNA detection on indium tin-oxide (ITO) coated glass slide. The morphology of SiNWs/AuNPs composite as the modifier layer on ITO was studied by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The morphological studies clearly showed that SiNWs were successfully decorated with 20 nm-AuNPs using self-assembly monolayer (SAM) technique. The effective surface area for SiNWs/AuNPs-modified ITO enhanced about 10 times compared with bare ITO electrode. SiNWs/AuNPs nanocomposite was further explored as a matrix for DNA probe immobilization in detection of dengue virus as a bio-sensing model to evaluate its performance in electrochemical sensors. The hybridization of complementary DNA was monitored by differential pulse voltammetry (DPV) using methylene blue (MB) as the redox indicator. The fabricated biosensor was able to discriminate significantly complementary, non-complementary and single-base mismatch oligonucleotides. The electrochemical biosensor was sensitive to target DNA related to dengue virus in the range of 9.0–178.0 ng/ml with detection limit of 3.5 ng/ml. In addition, SiNWs/AuNPs-modified ITO, regenerated up to 8 times and its stability was up to 10 weeks at 4 °C in silica gel. - Highlights: • A sensitive biosensor is presented for detection of dengue virus. • SiNWs and AuNPs used as nanocomposite layers on ITO for construction of biosensor • The detection mechanism is based on the interaction of MB with DNA bonded on AuNPs. • The reduction signal of MB decreases upon complementary hybridization.

  7. The utilization of SiNWs/AuNPs-modified indium tin oxide (ITO) in fabrication of electrochemical DNA sensor

    Rashid, Jahwarhar Izuan Abdul; Yusof, Nor Azah; Abdullah, Jaafar; Hashim, Uda; Hajian, Reza

    2014-01-01

    This work describes the incorporation of SiNWs/AuNPs composite as a sensing material for DNA detection on indium tin-oxide (ITO) coated glass slide. The morphology of SiNWs/AuNPs composite as the modifier layer on ITO was studied by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The morphological studies clearly showed that SiNWs were successfully decorated with 20 nm-AuNPs using self-assembly monolayer (SAM) technique. The effective surface area for SiNWs/AuNPs-modified ITO enhanced about 10 times compared with bare ITO electrode. SiNWs/AuNPs nanocomposite was further explored as a matrix for DNA probe immobilization in detection of dengue virus as a bio-sensing model to evaluate its performance in electrochemical sensors. The hybridization of complementary DNA was monitored by differential pulse voltammetry (DPV) using methylene blue (MB) as the redox indicator. The fabricated biosensor was able to discriminate significantly complementary, non-complementary and single-base mismatch oligonucleotides. The electrochemical biosensor was sensitive to target DNA related to dengue virus in the range of 9.0–178.0 ng/ml with detection limit of 3.5 ng/ml. In addition, SiNWs/AuNPs-modified ITO, regenerated up to 8 times and its stability was up to 10 weeks at 4 °C in silica gel. - Highlights: • A sensitive biosensor is presented for detection of dengue virus. • SiNWs and AuNPs used as nanocomposite layers on ITO for construction of biosensor • The detection mechanism is based on the interaction of MB with DNA bonded on AuNPs. • The reduction signal of MB decreases upon complementary hybridization

  8. Smoking modify the effects of polycyclic aromatic hydrocarbons exposure on oxidative damage to DNA in coke oven workers.

    Yang, Jin; Zhang, Hongjie; Zhang, Huitao; Wang, Wubin; Liu, Yanli; Fan, Yanfeng

    2017-07-01

    Coke oven emissions containing polycyclic aromatic hydrocarbons (PAHs) are predominant toxic constituents of particulate air pollution that have been linked to increased risk of lung cancer. Numerous epidemiological studies have suggested that oxidative DNA damage may play a pivotal role in the carcinogenic mechanism of lung cancer. Little is known about the effect of interaction between PAHs exposure and lifestyle on DNA oxidative damage. The study population is composed by coke oven workers (365) and water treatment workers (144), and their urinary levels of four PAH metabolites and 8-hydroxydeoxyguanosine (8-OHdG) were determined. Airborne samples of exposed sites (4) and control sites (3) were collected, and eight carcinogenic PAHs were detected by high-performance liquid chromatography. The median values of the sum of eight carcinogenic PAHs and BaP in exposed sites were significantly higher than control sites (P < 0.01). The study found that the urinary PAH metabolites were significantly elevated in coke oven workers (P < 0.01). Multivariate logistic regression analysis revealed that the risk of high levels of urinary 8-OHdG will increase with increasing age, cigarette consumption, and levels of urinary 1-hydroxypyrene, and P for trend were all <0.05. Smoking can significantly modify the effects of urinary 1-hydroxypyrene on high concentrations urinary 8-OHdG, during co-exposure to both light or heavy smoking and high 1-hydroxypyrene levels (OR 4.28, 95% CI 1.32-13.86 and OR 5.05, 95% CI 1.63-15.67, respectively). Our findings quantitatively demonstrate that workers exposed to coke oven fumes and smoking will cause more serious DNA oxidative damage.

  9. Cytogenetic status and oxidative DNA-damage induced by atorvastatin in human peripheral blood lymphocytes: Standard and Fpg-modified comet assay

    Gajski, Goran; Garaj-Vrhovac, Vera; Orescanin, Visnja

    2008-01-01

    To investigate the genotoxic potential of atorvastatin on human lymphocytes in vitro standard comet assay was used in the evaluation of basal DNA damage and to investigate possible oxidative DNA damage produced by reactive oxygen species (ROS) Fpg-modified version of comet assay was also conducted. In addition to these techniques the new criteria for scoring micronucleus test were applied for more complete detection of baseline damage in binuclear lymphocytes exposed to atorvastatin 80 mg/day in different time periods by virtue of measuring the frequency of micronuclei, nucleoplasmic bridges and nuclear buds. All parameters obtained with the standard comet assay and Fpg-modified comet assay were significantly higher in the treated than in control lymphocytes. The Fpg-modified comet assay showed a significantly greater tail length, tail intensity, and tail moment in all treated lymphocytes than did the standard comet assay, which suggests that oxidative stress is likely to be responsible for DNA damage. DNA damage detected by the standard comet assay indicates that some other mechanism is also involved. In addition to the comet assay, a total number of micronuclei, nucleoplasmic bridges and nuclear buds were significantly higher in the exposed than in controlled lymphocytes. Regression analyses showed a positive correlation between the results obtained by the comet (Fpg-modified and standard) and micronucleus assay. Overall, the study demonstrated that atorvastatin in its highest dose is capable of producing damage on the level of DNA molecule and cell

  10. Cytogenetic status and oxidative DNA-damage induced by atorvastatin in human peripheral blood lymphocytes: Standard and Fpg-modified comet assay

    Gajski, Goran [Institute for Medical Research and Occupational Health, Mutagenesis Unit, 10000 Zagreb (Croatia); Garaj-Vrhovac, Vera [Institute for Medical Research and Occupational Health, Mutagenesis Unit, 10000 Zagreb (Croatia); Orescanin, Visnja [Ruder Boskovic Institute, 10000 Zagreb (Croatia)

    2008-08-15

    To investigate the genotoxic potential of atorvastatin on human lymphocytes in vitro standard comet assay was used in the evaluation of basal DNA damage and to investigate possible oxidative DNA damage produced by reactive oxygen species (ROS) Fpg-modified version of comet assay was also conducted. In addition to these techniques the new criteria for scoring micronucleus test were applied for more complete detection of baseline damage in binuclear lymphocytes exposed to atorvastatin 80 mg/day in different time periods by virtue of measuring the frequency of micronuclei, nucleoplasmic bridges and nuclear buds. All parameters obtained with the standard comet assay and Fpg-modified comet assay were significantly higher in the treated than in control lymphocytes. The Fpg-modified comet assay showed a significantly greater tail length, tail intensity, and tail moment in all treated lymphocytes than did the standard comet assay, which suggests that oxidative stress is likely to be responsible for DNA damage. DNA damage detected by the standard comet assay indicates that some other mechanism is also involved. In addition to the comet assay, a total number of micronuclei, nucleoplasmic bridges and nuclear buds were significantly higher in the exposed than in controlled lymphocytes. Regression analyses showed a positive correlation between the results obtained by the comet (Fpg-modified and standard) and micronucleus assay. Overall, the study demonstrated that atorvastatin in its highest dose is capable of producing damage on the level of DNA molecule and cell.

  11. Genetic polymorphisms in DNA repair and oxidative stress pathways may modify the association between body size and postmenopausal breast cancer

    McCullough, L. E.; Eng, S. M.; Bradshaw, P. T.; Cleveland, R. J.; Steck, S. E.; Terry, M. B.; Shen, J.; Crew, K.D.; Rössner ml., Pavel; Ahn, J.; Ambrosone, Ch.B.; Teitelbaum, S. L.; Neugut, A. I.; Santella, R. M.; Gammon, M. D.

    2015-01-01

    Roč. 25, č. 4 (2015), s. 263-269 ISSN 1047-2797 Institutional support: RVO:68378041 Keywords : breast cancer * body mass index * oxidative stress * DNA repair * Epidemiology Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.335, year: 2015

  12. In Vivo Alkaline Comet Assay and Enzyme-modified Alkaline Comet Assay for Measuring DNA Strand Breaks and Oxidative DNA Damage in Rat Liver.

    Ding, Wei; Bishop, Michelle E; Lyn-Cook, Lascelles E; Davis, Kelly J; Manjanatha, Mugimane G

    2016-05-04

    Unrepaired DNA damage can lead to genetic instability, which in turn may enhance cancer development. Therefore, identifying potential DNA damaging agents is important for protecting public health. The in vivo alkaline comet assay, which detects DNA damage as strand breaks, is especially relevant for assessing the genotoxic hazards of xenobiotics, as its responses reflect the in vivo absorption, tissue distribution, metabolism and excretion (ADME) of chemicals, as well as DNA repair process. Compared to other in vivo DNA damage assays, the assay is rapid, sensitive, visual and inexpensive, and, by converting oxidative DNA damage into strand breaks using specific repair enzymes, the assay can measure oxidative DNA damage in an efficient and relatively artifact-free manner. Measurement of DNA damage with the comet assay can be performed using both acute and subchronic toxicology study designs, and by integrating the comet assay with other toxicological assessments, the assay addresses animal welfare requirements by making maximum use of animal resources. Another major advantage of the assays is that they only require a small amount of cells, and the cells do not have to be derived from proliferating cell populations. The assays also can be performed with a variety of human samples obtained from clinically or occupationally exposed individuals.

  13. High-performance liquid chromatography/electrospray mass spectrometry for the analysis of modified bases in DNA: 7-(2-hydroxyethyl)guanine, the major ethylene oxide-DNA adduct.

    Leclercq, L; Laurent, C; De Pauw, E

    1997-05-15

    A method was developed for the analysis of 7-(2-hydroxyethyl)guanine (7HEG), the major DNA adduct formed after exposure to ethylene oxide (EO). The method is based on DNA neutral thermal hydrolysis, adduct micro-concentration, and final characterization and quantification by HPLC coupled to single-ion monitoring electrospray mass spectrometry (HPLC/SIR-ESMS). The method was found to be selective, sensitive, and easy to handle with no need for enzymatic digestion or previous sample derivatization. Detection limit was found to be close to 1 fmol of adduct injected (10(-10) M), thus allowing the detection of approximately three modified bases on 10(8) intact nucleotides in blood sample analysis. Quantification results are shown for 7HEG after calf thymus DNA and blood exposure to various doses of EO, in both cases obtaining clear dose-response relationships.

  14. Peroxynitrite modified DNA presents better epitopes for anti-DNA autoantibodies in diabetes type 1 patients.

    Tripathi, Prashant; Moinuddin; Dixit, Kiran; Mir, Abdul Rouf; Habib, Safia; Alam, Khursheed; Ali, Asif

    2014-07-01

    Peroxynitrite (ONOO(-)), formed by the reaction between nitric oxide (NO) and superoxide (O2(-)), has been implicated in the etiology of numerous disease processes. Peroxynitrite interacts with DNA via direct oxidative reactions or via indirect radical-mediated mechanism. It can inflict both oxidative and nitrosative damages on DNA bases, generating abasic sites, resulting in the single strand breaks. Plasmid pUC 18 isolated from Escherichiacoli was modified with peroxynitrite, generated by quenched flow process. Modifications incurred in plasmid DNA were characterized by ultraviolet and fluorescence spectroscopy, circular dichroism, HPLC and melting temperature studies. Binding characteristics and specificity of antibodies from diabetes patients were analyzed by direct binding and inhibition ELISA. Peroxynitrite modification of pUC 18 plasmid resulted in the formation of strand breaks and base modification. The major compound formed when peroxynitrite reacted with DNA was 8-nitroguanine, a specific marker for peroxynitrite induced DNA damage in inflamed tissues. The concentration of 8-nitroguanine was found to be 3.8 μM. Sera from diabetes type 1 patients from different age groups were studied for their binding to native and peroxynitrite modified plasmid. Direct binding and competitive-inhibition ELISA results showed higher recognition of peroxynitrite modified plasmid, as compared to the native form, by auto-antibodies present in diabetes patients. The preferential recognition of modified plasmid by diabetes autoantibodies was further reiterated by gel shift assay. Experimentally induced anti-peroxynitrite-modified plasmid IgG was used as a probe to detect nitrosative lesions in the DNA isolated from diabetes patients. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. A novel electrochemical DNA biosensor based on a modified magnetic bar carbon paste electrode with Fe{sub 3}O{sub 4}NPs-reduced graphene oxide/PANHS nanocomposite

    Jahanbani, Shahriar; Benvidi, Ali, E-mail: abenvidi@yazd.ac.ir

    2016-11-01

    In this study, we have designed a label free DNA biosensor based on a magnetic bar carbon paste electrode (MBCPE) modified with nanomaterial of Fe{sub 3}O{sub 4}/reduced graphene oxide (Fe{sub 3}O{sub 4}NP-RGO) as a composite and 1- pyrenebutyric acid-N- hydroxysuccinimide ester (PANHS) as a linker for detection of DNA sequences. Probe (BRCA1 5382 insC mutation detection) strands were immobilized on the MBCPE/Fe{sub 3}O{sub 4}-RGO/PANHS electrode for the exact incubation time. The characterization of the modified electrode was studied using different techniques such as scanning electron microscopy (SEM), infrared spectroscopy (IR), vibrating sample magnetometer (VSM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry methods. Some experimental parameters such as immobilization time of probe DNA, time and temperature of hybridization process were investigated. Under the optimum conditions, the immobilization of the probe and its hybridization with the target DNA (Complementary DNA) were tested. This DNA biosensor revealed a good linear relationship between ∆ R{sub ct} and logarithm of the complementary target DNA concentration ranging from 1.0 × 10{sup −18} mol L{sup −1} to 1.0 × 10{sup −8} mol L{sup −1} with a correlation coefficient of 0.9935 and a detection limit of 2.8 × 10{sup −19} mol L{sup −1}. In addition, the mentioned biosensor was satisfactorily applied for discriminating of complementary sequences from non-complementary sequences. The constructed biosensor (MBCPE/Fe{sub 3}O{sub 4}-RGO/PANHS/ssDNA) with high sensitivity, selectivity, stability, reproducibility and low cost can be used for detection of BRCA1 5382 insC mutation. - Highlights: • We have designed a MBCPE/Fe{sub 3}O{sub 4}-RGO/PANHS/ssDNA for determination of BRCA1 5382. • The magnetic bar was used for fabrication of CPE for completely adsorption of Fe3O4-RGO. • The proposed electrode showed a detection limit as low as 2.8 × 10{sup −19} M for target

  16. Oxidative DNA damage & repair: An introduction.

    Cadet, Jean; Davies, Kelvin J A

    2017-06-01

    This introductory article should be viewed as a prologue to the Free Radical Biology & Medicine Special Issue devoted to the important topic of Oxidatively Damaged DNA and its Repair. This special issue is dedicated to Professor Tomas Lindahl, co-winner of the 2015 Nobel Prize in Chemistry for his seminal discoveries in the area repair of oxidatively damaged DNA. In the past several years it has become abundantly clear that DNA oxidation is a major consequence of life in an oxygen-rich environment. Concomitantly, survival in the presence of oxygen, with the constant threat of deleterious DNA mutations and deletions, has largely been made possible through the evolution of a vast array of DNA repair enzymes. The articles in this Oxidatively Damaged DNA & Repair special issue detail the reactions by which intracellular DNA is oxidatively damaged, and the enzymatic reactions and pathways by which living organisms survive such assaults by repair processes. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Oxidized DNA induces an adaptive response in human fibroblasts

    Kostyuk, Svetlana V., E-mail: svet.kostyuk@gmail.com [Research Centre for Medical Genetics, Russian Academy of Medical Sciences, Moscow (Russian Federation); Tabakov, Viacheslav J.; Chestkov, Valerij V.; Konkova, Marina S.; Glebova, Kristina V.; Baydakova, Galina V.; Ershova, Elizaveta S.; Izhevskaya, Vera L. [Research Centre for Medical Genetics, Russian Academy of Medical Sciences, Moscow (Russian Federation); Baranova, Ancha, E-mail: abaranov@gmu.edu [Research Centre for Medical Genetics, Russian Academy of Medical Sciences, Moscow (Russian Federation); Center for the Study of Chronic Metabolic Diseases, School of System Biology, George Mason University, Fairfax, VA 22030 (United States); Veiko, Natalia N. [Research Centre for Medical Genetics, Russian Academy of Medical Sciences, Moscow (Russian Federation)

    2013-07-15

    Highlights: • We describe the effects of gDNAOX on human fibroblasts cultivated in serum withdrawal conditions. • gDNAOX evokes an adaptive response in human fibroblasts. • gDNAOX increases the survival rates in serum starving cell populations. • gDNAOX enhances the survival rates in cell populations irradiated at 1.2 Gy dose. • gDNAOX up-regulates NRF2 and inhibits NF-kappaB-signaling. - Abstract: Cell-free DNA (cfDNA) released from dying cells contains a substantial proportion of oxidized nucleotides, thus, forming cfDNA{sup OX}. The levels of cfDNA{sup OX} are increased in the serum of patients with chronic diseases. Oxidation of DNA turns it into a stress signal. The samples of genomic DNA (gDNA) oxidized by H{sub 2}O{sub 2}in vitro (gDNA{sup OX}) induce effects similar to that of DNA released from damaged cells. Here we describe the effects of gDNA{sup OX} on human fibroblasts cultivated in the stressful conditions of serum withdrawal. In these cells, gDNA{sup OX} evokes an adaptive response that leads to an increase in the rates of survival in serum starving cell populations as well as in populations irradiated at the dose of 1.2 Gy. These effects are not seen in control populations of fibroblasts treated with non-modified gDNA. In particular, the exposure to gDNA{sup OX} leads to a decrease in the expression of the proliferation marker Ki-67 and an increase in levels of PSNA, a decrease in the proportion of subG1- and G2/M cells, a decrease in proportion of cells with double strand breaks (DSBs). Both gDNA{sup OX} and gDNA suppress the expression of DNA sensors TLR9 and AIM2 and up-regulate nuclear factor-erythroid 2 p45-related factor 2 (NRF2), while only gDNA{sup OX} inhibits NF-κB signaling. gDNA{sup OX} is a model for oxidized cfDNA{sup OX} that is released from the dying tumor cells and being carried to the distant organs. The systemic effects of oxidized DNA have to be taken into account when treating tumors. In particular, the damaged DNA

  18. Biofunctionalization of zinc oxide nanowires for DNA sensory applications

    Rudolph Bettina

    2011-01-01

    Full Text Available Abstract We report on the biofunctionalization of zinc oxide nanowires for the attachment of DNA target molecules on the nanowire surface. With the organosilane glycidyloxypropyltrimethoxysilane acting as a bifunctional linker, amino-modified capture molecule oligonucleotides have been immobilized on the nanowire surface. The dye-marked DNA molecules were detected via fluorescence microscopy, and our results reveal a successful attachment of DNA capture molecules onto the nanowire surface. The electrical field effect induced by the negatively charged attached DNA molecules should be able to control the electrical properties of the nanowires and gives way to a ZnO nanowire-based biosensing device.

  19. Chemically modified DNA : methods and applications

    Gjonaj, Lorina

    2013-01-01

    Over het toepassen van DNA in de chemie DNA is een fascinerend biopolymeer dat gemakkelijk gemanipuleerd kan worden. Doel van het onderzoek van Lorina Gjonaj was het ontwikkelen van nieuwe methodologie om DNA chemisch te modificeren. Verschillende functionaliteiten zijn aan DNA gekoppeld. Deze

  20. Oxidative DNA base modifications as factors in carcinogenesis

    Olinski, R.; Jaruga, P.; Zastawny, T.H.

    1998-01-01

    Reactive oxygen species can cause extensive DNA modifications including modified bases. Some of the DNA base damage has been found to possess premutagenic properties. Therefore, if not repaired, it can contribute to carcinogenesis. We have found elevated amounts of modified bases in cancerous and precancerous tissues as compared with normal tissues. Most of the agents used in anticancer therapy are paradoxically responsible for induction of secondary malignancies and some of them may generate free radicals. The results of our experiments provide evidence that exposure of cancer patients to therapeutic doses of ionizing radiation and anticancer drugs cause base modifications in genomic DNA of lymphocytes. Some of these base damages could lead to mutagenesis in critical genes and ultimately to secondary cancers such as leukemias. This may point to an important role of oxidative base damage in cancer initiation. Alternatively, the increased level of the modified base products may contribute to genetic instability and metastatic potential of tumor cells. (author)

  1. Synthesis and structural characterization of piperazino-modified DNA that favours hybridization towards DNA over RNA

    Skov, Joan; Bryld, Torsten; Lindegaard, Dorthe

    2011-01-01

    We report the synthesis of two C4'-modified DNA analogues and characterize their structural impact on dsDNA duplexes. The 4'-C-piperazinomethyl modification stabilizes dsDNA by up to 5°C per incorporation. Extension of the modification with a butanoyl-linked pyrene increases the dsDNA stabilizati...

  2. Modified iron oxide nanomaterials: Functionalization and application

    Bagheri, Samira; Julkapli, Nurhidayatullaili Muhd

    2016-01-01

    Iron oxide magnetic nanoparticles have aroused the interest of researchers of materials' chemistry due to its exceptional properties such as decent magnetic, electric, catalytic, biocompatibility, and low toxicity. However, these magnetic nanoparticles are predisposed towards aggregation and forming larger particles, due to its strong anisotropic dipolar interactions, particularly in the aqueous phase, consequently depriving them of dispersibility and particular properties, ultimately degrading their performance. Hence, this review focuses on modified magnetic nanoparticles that are stable, easily synthesized, possess a high surface area and could be facile-separated via magnetic forces, and are of low toxicity and costs for applications such as catalyst/catalyst support, food security, biomedical, and pollutant remediation. - Highlights: • Nanomagnetite is interesting due to its exceptional properties. • Nanomagnetite is predisposed towards aggregation and forming larger particles. • Modified nanomagnetite are stable, easily synthesized, possess high surface area. • Modified nanomagnetite got applications as catalyst/catalyst support.

  3. Modified iron oxide nanomaterials: Functionalization and application

    Bagheri, Samira; Julkapli, Nurhidayatullaili Muhd

    2016-10-15

    Iron oxide magnetic nanoparticles have aroused the interest of researchers of materials' chemistry due to its exceptional properties such as decent magnetic, electric, catalytic, biocompatibility, and low toxicity. However, these magnetic nanoparticles are predisposed towards aggregation and forming larger particles, due to its strong anisotropic dipolar interactions, particularly in the aqueous phase, consequently depriving them of dispersibility and particular properties, ultimately degrading their performance. Hence, this review focuses on modified magnetic nanoparticles that are stable, easily synthesized, possess a high surface area and could be facile-separated via magnetic forces, and are of low toxicity and costs for applications such as catalyst/catalyst support, food security, biomedical, and pollutant remediation. - Highlights: • Nanomagnetite is interesting due to its exceptional properties. • Nanomagnetite is predisposed towards aggregation and forming larger particles. • Modified nanomagnetite are stable, easily synthesized, possess high surface area. • Modified nanomagnetite got applications as catalyst/catalyst support.

  4. Automated DNA extraction from genetically modified maize using aminosilane-modified bacterial magnetic particles.

    Ota, Hiroyuki; Lim, Tae-Kyu; Tanaka, Tsuyoshi; Yoshino, Tomoko; Harada, Manabu; Matsunaga, Tadashi

    2006-09-18

    A novel, automated system, PNE-1080, equipped with eight automated pestle units and a spectrophotometer was developed for genomic DNA extraction from maize using aminosilane-modified bacterial magnetic particles (BMPs). The use of aminosilane-modified BMPs allowed highly accurate DNA recovery. The (A(260)-A(320)):(A(280)-A(320)) ratio of the extracted DNA was 1.9+/-0.1. The DNA quality was sufficiently pure for PCR analysis. The PNE-1080 offered rapid assay completion (30 min) with high accuracy. Furthermore, the results of real-time PCR confirmed that our proposed method permitted the accurate determination of genetically modified DNA composition and correlated well with results obtained by conventional cetyltrimethylammonium bromide (CTAB)-based methods.

  5. Experimental study of oxidative DNA damage

    Loft, Steffen; Deng, Xin-Sheng; Tuo, Jingsheng

    1998-01-01

    Animal experiments allow the study of oxidative DNA damage in target organs and the elucidation of dose-response relationships of carcinogenic and other harmful chemicals and conditions as well as the study of interactions of several factors. So far the effects of more than 50 different chemical ...

  6. Tobacco smoking and oxidative stress to DNA

    Ellegaard, Pernille Kempel; Poulsen, Henrik Enghusen

    2016-01-01

    Oxidative stress to DNA from smoking was investigated in one randomized smoking cessation study and in 36 cohort studies from excretion of urinary 8-oxo-7-hydrodeoxyguanosine (8-oxodG). Meta-analysis of the 36 cohort studies showed smoking associated with a 15.7% (95% CL 11.0:20.3, p < 0.0001) in...

  7. Site-specifically modified oligodeoxyribonucleotides as templates for Escherichia coli DNA polymerase I

    O'Connor, D.; Stoehrer, G.

    1985-01-01

    Oligodeoxyribonucleotides with site-specific modifications have been used as substrates for Escherichia coli DNA polymerase I holoenzyme and Klenow fragment. Modifications included the bulky guanine-8-aminofluorene adduct and a guanine oxidation product resembling the product of photosensitized DNA oxidation. By a combination of primers and nick-mers, conditions of single-strand-directed DNA synthesis and nick-translation could be created. The results show that the polymerase can bypass both types of lesions. Bypass occurs on a single-stranded template but is facilitated on a nicked, double-stranded template. Only purines, with guanine more favored than adenine, are incorporated across both lesions. The results indicate that site-specifically modified oligonucleotides can be sensitive probes for the action of polymerases on damaged templates. They also suggest a function for polymerase I, in its nick-translation capacity, during DNA repair and mutagenesis

  8. DNA repair is responsible for the presence of oxidatively damaged DNA lesions in urine

    Cooke, Marcus S.; Evans, Mark D.; Dove, Rosamund; Rozalski, Rafal; Gackowski, Daniel; Siomek, Agnieszka; Lunec, Joseph; Olinski, Ryszard

    2005-01-01

    The repair of oxidatively damaged DNA is integral to the maintenance of genomic stability, and hence prevention of a wide variety of pathological conditions, such as aging, cancer and cardiovascular disease. The ability to non-invasively assess DNA repair may provide information regarding repair pathways, variability in repair capacity, and susceptibility to disease. The development of assays to measure urinary DNA lesions offered this potential, although it rapidly became clear that possible contribution from diet and cell turnover may influence urinary lesion levels. Whilst early studies attempted to address these issues, up until now, much of the data appears conflicting. However, recent work from our laboratories, in which human volunteers were fed highly oxidatively modified 15 N-labelled DNA demonstrates that diet does not appear to contribute to urinary levels of 8-hydroxyguanine and 7,8-dihydro-8-oxo-2'-deoxyguanosine. Furthermore, we propose that a number of literature reports form an argument against a contribution from cell death. Indeed we, and others, have presented evidence, which strongly suggests the involvement of cell death to be minimal. Taken together, these data would appear to rule out various confounding factors, leaving DNA repair pathways as the principal source of urinary purine, if not DNA, lesions enabling such measurements to be used as indicators of repair

  9. Oxidative Stress, DNA Damage and DNA Repair in Female Patients with Diabetes Mellitus Type 2.

    Annemarie Grindel

    Full Text Available Diabetes mellitus type 2 (T2DM is associated with oxidative stress which in turn can lead to DNA damage. The aim of the present study was to analyze oxidative stress, DNA damage and DNA repair in regard to hyperglycemic state and diabetes duration.Female T2DM patients (n = 146 were enrolled in the MIKRODIAB study and allocated in two groups regarding their glycated hemoglobin (HbA1c level (HbA1c≤7.5%, n = 74; HbA1c>7.5%, n = 72. In addition, tertiles according to diabetes duration (DD were created (DDI = 6.94±3.1 y, n = 49; DDII = 13.35±1.1 y, n = 48; DDIII = 22.90±7.3 y, n = 49. Oxidative stress parameters, including ferric reducing ability potential, malondialdehyde, oxidized and reduced glutathione, reduced thiols, oxidized LDL and F2-Isoprostane as well as the activity of antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase were measured. Damage to DNA was analyzed in peripheral blood mononuclear cells and whole blood with single cell gel electrophoresis. DNA base excision repair capacity was tested with the modified comet repair assay. Additionally, mRNA expressions of nine genes related to base excision repair were analyzed in a subset of 46 matched individuals.No significant differences in oxidative stress parameters, antioxidant enzyme activities, damage to DNA and base excision repair capacity, neither between a HbA1c cut off />7.5%, nor between diabetes duration was found. A significant up-regulation in mRNA expression was found for APEX1, LIG3 and XRCC1 in patients with >7.5% HbA1c. Additionally, we observed higher total cholesterol, LDL-cholesterol, LDL/HDL-cholesterol, triglycerides, Framingham risk score, systolic blood pressure, BMI and lower HDL-cholesterol in the hyperglycemic group.BMI, blood pressure and blood lipid status were worse in hyperglycemic individuals. However, no major disparities regarding oxidative stress, damage to DNA and DNA repair were present which might be due to good medical

  10. SUMO-2 Orchestrates Chromatin Modifiers in Response to DNA Damage

    Hendriks, Ivo A; Treffers, Louise W; Verlaan-de Vries, Matty

    2015-01-01

    dynamically SUMOylated interaction networks of chromatin modifiers, transcription factors, DNA repair factors, and nuclear body components. SUMOylated chromatin modifiers include JARID1B/KDM5B, JARID1C/KDM5C, p300, CBP, PARP1, SetDB1, and MBD1. Whereas SUMOylated JARID1B was ubiquitylated by the SUMO......-targeted ubiquitin ligase RNF4 and degraded by the proteasome in response to DNA damage, JARID1C was SUMOylated and recruited to the chromatin to demethylate histone H3K4....

  11. Photocatalysis of Modified Transition Metal Oxide Surfaces

    Batzill, Matthias [Univ. of South Florida, Tampa, FL (United States). Dept. of Physics

    2018-02-28

    The goal of this project has been to establish a cause-effect relationship for photocatalytic activity variations of different structures of the same material; and furthermore gain fundamental understanding on modification of photocatalysts by compositional or surface modifications. The reasoning is that gaining atomic scale understanding of how surface and bulk modifications alter the photo reactivity will lead to design principles for next generation photocatalysts. As a prototypical photocatalyst the research focused on TiO2 synthesized in well-defined single crystalline form to enable fundamental characterizations.We have obtained results in the following areas: (a) Preparation of epitaxial anatase TiO2 samples by pulsed laser deposition. (b) Comparison of hydrogen diffusion on different crystallographic surface. (c) Determining the stability of the TiO2(011)-2x1 reconstruction upon interactions with adsorbates. (d) Characterization of adsorption and (thermal and photo) reaction of molecules with nitro-endgroups, (e) Exploring the possibility of modifying planar model photocatalyst surfaces with graphene to enable fundamental studies on reported enhanced photocatalytic activities of graphene modified transition metal oxides, (f) gained fundamental understanding on the role of crystallographic polymorphs of the same material for their photocatalytic activities.

  12. Photosensitized oxidation of DNA and its components

    Decarroz, Chantal.

    1982-09-01

    Chemical changes in DNA components during the photodynamic effect are responsible for Mutagenic and carcinogenic phenomena. Basically two competitive mechanisns involving respectively a charge transfer (type I) and singlet oxygen (type II) are implicated in reactions photo-sensitized by different agents (acridines, phenothiazines, porphyrins, flavins, psoralenes...). A study of the photosensitized oxidation of DNA itself was approached through characterization of the main final products in the case of purine nucleosides. Methyl-2 naphthoquinone - 1,4 (vitamin K 3 ) displays a special photosensitization mechanism involving a cation radical type of intermediary [fr

  13. Inflammation, oxidative DNA damage, and carcinogenesis

    Lewis, J.G.; Adams, D.O.

    1987-01-01

    Inflammation has long been associated with carcinogenesis, especially in the promotion phase. The mechanism of action of the potent inflammatory agent and skin promoter 12-tetradecanoyl phorbol-13-acetate (TPA) is unknown. It is though that TPA selectively enhances the growth of initiated cells, and during this process, initiated cells progress to the preneoplastic state and eventually to the malignant phenotype. The authors and others have proposed that TPA may work, in part, by inciting inflammation and stimulating inflammatory cells to release powerful oxidants which then induce DNA damage in epidermal cells. Macrophages cocultured with target cells and TPA induce oxidized thymine bases in the target cells. This process is inhibited by both catalase and inhibitors of lipoxygenases, suggesting the involvement of both H 2 O 2 and oxidized lipid products. In vivo studies demonstrated that SENCAR mice, which are sensitive to promotion by TPA, have a more intense inflammatory reaction in skin that C57LB/6 mice, which are resistant to promotion by TPA. In addition, macrophages from SENCAR mice release more H 2 O 2 and metabolites of AA, and induce more oxidative DNA damage in cocultured cells than macrophages from C57LB/6 mice. These data support the hypothesis that inflammation and the release of genotoxic oxidants may be one mechanism whereby initiated cells receive further genetic insults. They also further complicate risk assessment by suggesting that some environmental agents may work indirectly by subverting host systems to induce damage rather than maintaining homeostasis

  14. Thyroid hormone-induced oxidative damage on lipids, glutathione and DNA in the mouse heart.

    Gredilla, R; Barja, G; López-Torres, M

    2001-10-01

    Oxygen radicals of mitochondrial origin are involved in oxidative damage. In order to analyze the possible relationship between metabolic rate, oxidative stress and oxidative damage, OF1 female mice were rendered hyper- and hypothyroid by chronic administration of 0.0012% L-thyroxine (T4) and 0.05% 6-n-propyl-2-thiouracil (PTU), respectively, in their drinking water for 5 weeks. Hyperthyroidism significantly increased the sensitivity to lipid peroxidation in the heart, although the endogenous levels of lipid peroxidation were not altered. Thyroid hormone-induced oxidative stress also resulted in higher levels of GSSG and GSSG/GSH ratio. Oxidative damage to mitochondrial DNA was greater than that to genomic DNA. Hyperthyroidism decreased oxidative damage to genomic DNA. Hypothyroidism did not modify oxidative damage in the lipid fraction but significantly decreased GSSG and GSSG/GSH ratio and oxidative damage to mitochondrial DNA. These results indicate that thyroid hormones modulate oxidative damage to lipids and DNA, and cellular redox potential in the mouse heart. A higher oxidative stress in the hyperthyroid group is presumably neutralized in the case of nuclear DNA by an increase in repair activity, thus protecting this key molecule. Treatment with PTU, a thyroid hormone inhibitor, reduced oxidative damage in the different cell compartments.

  15. Immunochemical detection of oxidatively damaged DNA

    Rössner ml., Pavel; Šrám, Radim

    2012-01-01

    Roč. 46, č. 4 (2012), s. 492-522 ISSN 1071-5762 R&D Projects: GA MŽP(CZ) SP/1B3/50/07; GA MŠk 2B08005; GA ČR GAP503/11/0084 Institutional research plan: CEZ:AV0Z50390703 Institutional support: RVO:68378041 Keywords : oxidative DNA damage * ELISA * immunohistochemistry Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 3.279, year: 2012

  16. Glucose Oxidation on Gold-modified Copper Electrode

    Lim, Jieun; Pyo, Sung Gyu; Son, Hyungbin; Kim, Sookil [Chung-Ang Univ., Seoul (Korea, Republic of); Ahn, Sang Hyun; Son, Hyungbin [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2013-09-15

    The activities of Au-modified Cu electrodes toward glucose oxidation are evaluated according to their fabrication conditions and physico-chemical properties. The Au-modified Cu electrodes are fabricated by the galvanic displacement of Au on a Cu substrate and the characteristics of the Au particles are controlled by adjusting the displacement time. From the glucose oxidation tests, it is found that the Au modified Cu has superior activity to the pure Au or Cu film, which is evidenced by the negative shift in the oxidation potential and enhanced current density during the electrochemical oxidation. Though the activity of the Au nanoparticles is a contributing factor, the enhanced activity of the Au-modified Cu electrode is due to the increased oxidation number of Cu through the electron transfer from Cu to more electronegative Au. The depletion of electron in Cu facilitates the oxidation of glucose. The stability of the Au-modified Cu electrode was also studied by chronoamperometry.

  17. Genotoxic effect and antigen binding characteristics of SLE auto-antibodies to peroxynitrite-modified human DNA.

    Khan, Md Asad; Alam, Khursheed; Mehdi, Syed Hassan; Rizvi, M Moshahid A

    2017-12-01

    Systemic lupus erythematosus (SLE) is an inflammatory autoimmune disease characterized by auto-antibodies against native deoxyribonucleic acid after modification and is one of the reasons for the development of SLE. Here, we have evaluated the structural perturbations in human placental DNA by peroxynitrite using spectroscopy, thermal denaturation and high-performance liquid chromatography (HPLC). Peroxynitrite is a powerful potent bi-functional oxidative/nitrative agent that is produced both endogenously and exogenously. In experimental animals, the peroxynitrite-modified DNA was found to be highly immunogenic. The induced antibodies showed cross-reactions with different types of DNA and nitrogen bases that were modified with peroxynitrite by inhibition ELISA. The antibody activity was inhibited by approximately 89% with its immunogen as the inhibitor. The antigen-antibodies interaction between induced antibodies with peroxynitrite-modified DNA showed retarded mobility as compared to the native form. Furthermore, significantly increased binding was also observed in SLE autoantibodies with peroxynitrite-modified DNA than native form. Moreover, DNA isolated from lymphocyte of SLE patients revealed significant recognition of anti-peroxynitrite-modified DNA immunoglobulin G (IgG). Our data indicates that DNA modified with peroxynitrite presents unique antigenic determinants that may induce autoantibody response in SLE. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Oxidatively Modified Proteins in the Serous Subtype of Ovarian Carcinoma

    Sharifeh Mehrabi

    2014-01-01

    Full Text Available Serous subtype of ovarian cancer is considered to originate from fallopian epithelium mucosa that has been exposed to physiological changes resulting from ovulation. Ovulation influences an increased in inflammation of epithelial ovarian cells as results of constant exposure of cells to ROS. The imbalance between ROS and antioxidant capacities, as well as a disruption of redox signaling, causes a wide range of damage to DNA, proteins, and lipids. This study applied spectrophotometric, dinitrophenylhydrazone (DNPH assay, two-dimensional gel electrophoresis, and Western blot analyses to assess the levels of oxidatively modified proteins in 100 primary serous epithelial ovarian carcinoma and normal/surrounding tissues. These samples were obtained from 56 Caucasian and 44 African-American patients within the age range of 61±10 years. Analyses showed that the levels of reactive protein carbonyl groups increased as stages progressed to malignancy. Additionally, the levels of protein carbonyls in serous ovarian carcinoma among African Americans are 40% (P<0.05 higher relative to Caucasian at similar advanced stages. Results suggest that oxidative stress is involved in the modification of carbonyl protein groups, leading to increased aggressiveness of epithelial ovarian tumors and may contribute to the disease's invasiveness among African Americans.

  19. Single Molecule Scanning of DNA Radiation Oxidative Damage, Phase I

    National Aeronautics and Space Administration — This proposal will develop an assay to map genomic DNA, at the single molecule level and in a nanodevice, for oxidative DNA damage arising from radiation exposure;...

  20. ATM-dependent pathways of chromatin remodelling and oxidative DNA damage responses.

    Berger, N Daniel; Stanley, Fintan K T; Moore, Shaun; Goodarzi, Aaron A

    2017-10-05

    Ataxia-telangiectasia mutated (ATM) is a serine/threonine protein kinase with a master regulatory function in the DNA damage response. In this role, ATM commands a complex biochemical network that signals the presence of oxidative DNA damage, including the dangerous DNA double-strand break, and facilitates subsequent repair. Here, we review the current state of knowledge regarding ATM-dependent chromatin remodelling and epigenomic alterations that are required to maintain genomic integrity in the presence of DNA double-strand breaks and/or oxidative stress. We will focus particularly on the roles of ATM in adjusting nucleosome spacing at sites of unresolved DNA double-strand breaks within complex chromatin environments, and the impact of ATM on preserving the health of cells within the mammalian central nervous system.This article is part of the themed issue 'Chromatin modifiers and remodellers in DNA repair and signalling'. © 2017 The Author(s).

  1. Aging and oxidatively damaged nuclear DNA in animal organs

    Møller, Peter; Løhr, Mille; Folkmann, Janne K

    2010-01-01

    Oxidative stress is considered to contribute to aging and is associated with the generation of oxidatively damaged DNA, including 8-oxo-7,8-dihydroguanine. We have identified 69 studies that have measured the level of oxidatively damaged DNA in organs of animals at various ages. In general, organs...... with limited cell proliferation, i.e., liver, kidney, brain, heart, pancreas, and muscle, tended to show accumulation of DNA damage with age, whereas organs with highly proliferating cells, such as intestine, spleen, and testis, showed more equivocal or no effect of age. A restricted analysis of studies...... evidence for aging-associated accumulation of oxidatively damaged DNA in organs with limited cell proliferation....

  2. DNA oxidation and DNA repair in gills of zebra mussels exposed to cadmium and benzo(a)pyrene.

    Michel, Cécile; Vincent-Hubert, Françoise

    2015-11-01

    Freshwater bivalve molluscs are considered as effective indicators of environmental pollution. The comet assay allows the detection of DNA damage such as DNA strand breaks and alkali-labile sites. The main oxidative lesion, 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), which is a pre-mutagenic lesion, can be detected by the comet assay coupled with the hOGG1 DNA repair enzyme. With this modified assay we recently observed that BaP induced 8-oxodG lesions and with the modified comet-Fpg assay we observed that Cd induced oxidative DNA damage. The aim of this study was to determine the stability of DNA lesions in Cd and BaP exposed zebra mussels using the comet-hOGG1 assay. Mussels were exposed for 24 h to these two chemicals and then placed in clean water for 6 days. We observed that BaP (7, 12 and 18 µg/L) induced an increase of DNA strand break levels as soon as 6 h of exposure and that the two highest concentrations of BaP induced a low level of hOGG1-sensitive sites. After 2 days of depuration, BaP induced DNA lesions returned to the basal level, indicating an effective DNA repair. Cd (3, 32 and 81 µg/L) induced an increase of the DNA strand break levels and a low level of hOGG1-sensitive sites. This study revealed that BaP-induced DNA lesions are repaired more efficiently than Cd-induced DNA lesions. As the level of hOGG1 sensitive sites was increased in Cd and BaP exposed mussels, it seems that these chemicals induce 8-oxo-dG.

  3. Hydrophobically modified chitosan/gold nanoparticles for DNA delivery

    Bhattarai, Shanta Raj; Remant Bahadur, K.C.; Aryal, Santosh; Bhattarai, Narayan; Kim, Sun Young; Yi, Ho Keun; Hwang, Pyoung Han; Kim, Hak Yong

    2008-01-01

    Present study dealt an application of modified chitosan gold nanoparticles (Nac-6-Au) for the immobilization of necked plasmid DNA. Gold nanoparticles stabilized with N-acylated chitosan were prepared by graft-onto approach. The stabilized gold nanoparticles were characterized by different physico-chemical techniques such as UV-vis, TEM, ELS and DLS. MTT assay was used for in vitro cytotoxicity of the nanoparticles into three different cell lines (NIH 3T3, CT-26 and MCF-7). The formulation of plasmid DNA with the nanoparticles corresponds to the complex forming capacity and in-vitro/in-vivo transfection efficiency was studied via gel electrophoresis and transfection methods, respectively. Results showed the modified chitosan gold nanoparticles were well-dispersed and spherical in shape with average size around 10∼12 nm in triple distilled water at pH 7.4, and showed relatively no cytotoxicity at low concentration. Addition of plasmid DNA on the aqueous solution of the nanoparticles markedly reduced surface potential (50.0∼66.6%) as well as resulted in a 13.33% increase in hydrodynamic diameters of the formulated nanoparticles. Transfection efficiency of Nac-6-Au/DNA was dependent on cell type, and higher β-galactosidase activity was observed on MCF-7 breast cancer cell. Typically, this activity was 5 times higher in 4.5 mg/ml nanoparticles concentration than that achieved by the nanoparticles of other concentrations (and/or control). However, this activity was lower in in-vitro and dramatically higher in in-vivo than that of commercially available transfection kit (Lipofectin (registered) ) and DNA. From these results, it can be expected to develop alternative new vectors for gene delivery

  4. Platinated DNA oligonucleotides: new probes forming ultrastable conjugates with graphene oxide

    Wang, Feng; Liu, Juewen

    2014-05-01

    Metal containing polymers have expanded the property of polymers by involving covalently associated metal complexes. DNA is a special block copolymer. While metal ions are known to influence DNA, little is explored on its polymer property when strong metal complexes are associated. In this work, we study cisplatin modified DNA as a new polymer and probe. Out of the complexes formed between cisplatin-A15, HAuCl4-A15, Hg2+-T15 and Ag+-C15, only the cisplatin adduct is stable under the denaturing gel electrophoresis condition. Each Pt-nucleobase bond gives a positive charge and thus makes DNA a zwitterionic polymer. This allows ultrafast adsorption of DNA by graphene oxide (GO) and the adsorbed complex is highly stable. Non-specific DNA, protein, surfactants and thiolated compounds cannot displace platinated DNA from GO, while non-modified DNA is easily displaced in most cases. The stable GO/DNA conjugate is further tested for surface hybridization. This is the first demonstration of using metallated DNA as a polymeric material for interfacing with nanoscale materials.Metal containing polymers have expanded the property of polymers by involving covalently associated metal complexes. DNA is a special block copolymer. While metal ions are known to influence DNA, little is explored on its polymer property when strong metal complexes are associated. In this work, we study cisplatin modified DNA as a new polymer and probe. Out of the complexes formed between cisplatin-A15, HAuCl4-A15, Hg2+-T15 and Ag+-C15, only the cisplatin adduct is stable under the denaturing gel electrophoresis condition. Each Pt-nucleobase bond gives a positive charge and thus makes DNA a zwitterionic polymer. This allows ultrafast adsorption of DNA by graphene oxide (GO) and the adsorbed complex is highly stable. Non-specific DNA, protein, surfactants and thiolated compounds cannot displace platinated DNA from GO, while non-modified DNA is easily displaced in most cases. The stable GO/DNA conjugate

  5. Immobilization, hybridization, and oxidation of synthetic DNA on gold surface: Electron transfer investigated by electrochemistry and scanning tunneling microscopy

    McEwen, Gerald D.; Chen Fan [Biological Engineering Program, Department of Biological and Irrigation Engineering, Utah State University, 4105 Old Main Hill, Logan, UT 84322-4105 (United States); Zhou Anhong, E-mail: Anhong.Zhou@usu.edu [Biological Engineering Program, Department of Biological and Irrigation Engineering, Utah State University, 4105 Old Main Hill, Logan, UT 84322-4105 (United States)

    2009-06-08

    Fundamental understanding of interfacial electron transfer (ET) among electrolyte/DNA/solid-surface will facilitate the design for electrical detection of DNA molecules. In this report, the electron transfer characteristics of synthetic DNA (sequence from pathogenic Cryptosporidium parvum) self-assembled on a gold surface was electrochemically studied. The effects of immobilization order on the interface ET related parameters such as diffusion coefficient (D{sub 0}), surface coverage ({theta}{sub R}), and monolayer thickness (d{sub i}) were determined by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). DNA surface density ({Gamma}{sub DNA}) was determined by the integration of the charge of the electro-oxidation current peaks during the initial cyclic voltammetry scans. It was found that the DNA surface densities at different modifications followed the order: {Gamma}{sub DNA} (dsS-DNA/Au) > {Gamma}{sub DNA} (MCH/dsS-DNA/Au) > {Gamma}{sub DNA} (dsS-DNA/MCH/Au). It was also revealed that the electro-oxidation of the DNA modified gold surface would involve the oxidation of nucleotides (guanine and adenine) with a 5.51 electron transfer mechanism and the oxidative desorption of DNA and MCH molecules by a 3 electron transfer mechanism. STM topography and current image analysis indicated that the surface conductivity after each surface modification followed the order: dsS-DNA/Au < MCH/dsS-DNA/Au < oxidized MCH/dsS-DNA/Au < Hoechst/oxidized MCH/dsS-DNA/Au. The results from this study suggested a combination of variations in immobilization order may provide an alternative approach for the optimization of DNA hybridization and the further development for electrical detection of DNA.

  6. Increased urinary excretion of 8-oxo-2'-deoxyguanosine, a biomarker of oxidative DNA damage, in urban bus drivers

    Loft, S; Poulsen, H E; Vistisen, K

    1999-01-01

    Oxidative damage to DNA could be involved in the increased risk of cancer associated with exposure to polluted urban air, which contains a number of oxidants. CYP1A2 is induced by and metabolizes polyaromatic hydrocarbons (PAH) and aromatic amines and could modify effects of exposure to ambient air...... pollution. Similarly, DNA repair may be influenced by occupational and other exposures as well as modify the effect of DNA damaging agents. As part of a large investigation of the genotoxic burden to diesel exposed workers in transport sectors we studied oxidative DNA damage in 57 non-smoking bus drivers...... from the greater Copenhagen area. The drivers were studied on a workday and on a day off work. Comparisons were made between drivers from the central (n=30) and rural/suburban (n=27) areas of Copenhagen. The rate of oxidative DNA damage was estimated from 24 h urinary excretion of 8-oxo-2...

  7. Oxidative DNA damage during night shift work.

    Bhatti, Parveen; Mirick, Dana K; Randolph, Timothy W; Gong, Jicheng; Buchanan, Diana Taibi; Zhang, Junfeng Jim; Davis, Scott

    2017-09-01

    We previously reported that compared with night sleep, day sleep among shift workers was associated with reduced urinary excretion of 8-hydroxydeoxyguanosine (8-OH-dG), potentially reflecting a reduced ability to repair 8-OH-dG lesions in DNA. We identified the absence of melatonin during day sleep as the likely causative factor. We now investigate whether night work is also associated with reduced urinary excretion of 8-OH-dG. For this cross-sectional study, 50 shift workers with the largest negative differences in night work versus night sleep circulating melatonin levels (measured as 6-sulfatoxymelatonin in urine) were selected from among the 223 shift workers included in our previous study. 8-OH-dG concentrations were measured in stored urine samples using high performance liquid chromatography with electrochemical detection. Mixed effects models were used to compare night work versus night sleep 8-OH-dG levels. Circulating melatonin levels during night work (mean=17.1 ng/mg creatinine/mg creatinine) were much lower than during night sleep (mean=51.7 ng/mg creatinine). In adjusted analyses, average urinary 8-OH-dG levels during the night work period were only 20% of those observed during the night sleep period (95% CI 10% to 30%; psleep, is associated with reduced repair of 8-OH-dG lesions in DNA and that the effect is likely driven by melatonin suppression occurring during night work relative to night sleep. If confirmed, future studies should evaluate melatonin supplementation as a means to restore oxidative DNA damage repair capacity among shift workers. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  8. Mechanizm of propylene oxidation on modified cobalt-molybdenum catalysts

    Kutyrev, M.Yu.; Rozentuller, B.V.; Isaev, O.V.; Margolis, L.Ya.; Krylov, O.V.

    1977-01-01

    Effect is studied of additions of iron, copper, nickel, and vanadium oxides, introduced into cobalt, molybdate, on oxidation reactions of propylene to acrolein and acrylicacid. The principal parameters determining the activity and selectivity of oxidation of propylene and acrolein on modified cobalt molibdate are the structure, the type of Mo-O bond, and the nature of the electron transitions in the solid under the effect of adsorption of the reaction components

  9. Application of Ferriferous Oxide Modified by Chitosan in Gene Delivery

    Yu Kuang

    2012-01-01

    Full Text Available New approaches to improve the traditional gene carriers are still required. Here we explore Fe3O4 modified with degradable polymers that enhances gene delivery and target delivery using permanent magnetic field. Two magnetic Fe3O4 nanoparticles coated with chitosan (CTS and polyethylene glycol (PEG were synthesized by means of controlled chemical coprecipitation. Plasmid pEGFP was encapsulated as a reported gene. The ferriferous oxide complexes were approximately spherical; surface charge of CTS-Fe3O4 and PEG-Fe3O4 was about 20 mv and 0 mv, respectively. The controlled release of DNA from the CTS-Fe3O4 nanoparticles was observed. Concurrently, a desired Fe3O4 concentration of less than 2 mM was verified as safe by means of a cytotoxicity test in vitro. Presence of the permanent magnetic field significantly increased the transfection efficiency. Furthermore, the passive target property and safety of magnetic nanoparticles were also demonstrated in an in vivo test. The novel gene delivery system was proved to be an effective tool required for future target expression and gene therapy in vivo.

  10. Dextran-modified iron oxide nanoparticles

    Hradil, Jiří; Pisarev, A. G.; Babič, Michal; Horák, Daniel

    2007-01-01

    Roč. 5, 1-2 (2007), s. 162-168 ISSN 1672-2515 R&D Projects: GA ČR GA203/05/2256 Institutional research plan: CEZ:AV0Z40500505 Keywords : iron oxide * nanoparticles * dextran Subject RIV: CD - Macromolecular Chemistry

  11. Direct Coal Oxidation in Modified Solid Oxide Fuel Cells

    Deleebeeck, Lisa; Gil, Vanesa; Ippolito, Davide

    2015-01-01

    Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon-carbonate s......Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon......-carbonate slurry or anode layer. The nature of the coal affects both open circuit voltage and power output. Highest OCV and power densities were observed for bituminous coal and by adding manganese oxide or praseodymium-doped ceria to the carbon/carbonate mixture. Comparing the carbon black fueled performance...... bituminous coal (73 mW/cm2). © 2015 ECS - The Electrochemical Society...

  12. Direct Coal Oxidation in Modified Solid Oxide Fuel Cells

    Deleebeeck, Lisa; Gil, Vanesa; Ippolito, Davide

    2017-01-01

    Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon-carbonate s......Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon......-carbonate slurry or anode layer. The nature of the coal affects both open circuit voltage and power output. Highest OCV and power densities were observed for bituminous coal and by adding manganese oxide or praseodymium-doped ceria to the carbon/carbonate mixture. Comparing the carbon black fueled performance...... bituminous coal (73 mW/cm2)....

  13. Increased oxidative DNA damage in mononuclear leukocytes in vitiligo

    Giovannelli, Lisa [Department of Preclinical and Clinical Pharmacology, University of Florence, Viale Pieraccini 6, 50139 Florence (Italy)]. E-mail: lisag@pharm.unifi.it; Bellandi, Serena [Department of Dermatological Sciences, University of Florence, Viale Pieraccini 6, 50139 Florence (Italy); Pitozzi, Vanessa [Department of Preclinical and Clinical Pharmacology, University of Florence, Viale Pieraccini 6, 50139 Florence (Italy); Fabbri, Paolo [Department of Dermatological Sciences, University of Florence, Viale Pieraccini 6, 50139 Florence (Italy); Dolara, Piero [Department of Preclinical and Clinical Pharmacology, University of Florence, Viale Pieraccini 6, 50139 Florence (Italy); Moretti, Silvia [Department of Dermatological Sciences, University of Florence, Viale Pieraccini 6, 50139 Florence (Italy)

    2004-11-22

    Vitiligo is an acquired pigmentary disorder of the skin of unknown aetiology. The autocytotoxic hypothesis suggests that melanocyte impairment could be related to increased oxidative stress. Evidences have been reported that in vitiligo oxidative stress might also be present systemically. We used the comet assay (single cell alkaline gel electrophoresis) to evaluate DNA strand breaks and DNA base oxidation, measured as formamidopyrimidine DNA glycosylase (FPG)-sensitive sites, in peripheral blood cells from patients with active vitiligo and healthy controls. The basal level of oxidative DNA damage in mononuclear leukocytes was increased in vitiligo compared to normal subjects, whereas DNA strand breaks (SBs) were not changed. This alteration was not accompanied by a different capability to respond to in vitro oxidative challenge. No differences in the basal levels of DNA damage in polymorphonuclear leukocytes were found between patients and healthy subjects. Thus, this study supports the hypothesis that in vitiligo a systemic oxidative stress exists, and demonstrates for the first time the presence of oxidative alterations at the nuclear level. The increase in oxidative DNA damage shown in the mononuclear component of peripheral blood leukocytes from vitiligo patients was not particularly severe. However, these findings support an adjuvant role of antioxidant treatment in vitiligo.

  14. Increased oxidative DNA damage in mononuclear leukocytes in vitiligo

    Giovannelli, Lisa; Bellandi, Serena; Pitozzi, Vanessa; Fabbri, Paolo; Dolara, Piero; Moretti, Silvia

    2004-01-01

    Vitiligo is an acquired pigmentary disorder of the skin of unknown aetiology. The autocytotoxic hypothesis suggests that melanocyte impairment could be related to increased oxidative stress. Evidences have been reported that in vitiligo oxidative stress might also be present systemically. We used the comet assay (single cell alkaline gel electrophoresis) to evaluate DNA strand breaks and DNA base oxidation, measured as formamidopyrimidine DNA glycosylase (FPG)-sensitive sites, in peripheral blood cells from patients with active vitiligo and healthy controls. The basal level of oxidative DNA damage in mononuclear leukocytes was increased in vitiligo compared to normal subjects, whereas DNA strand breaks (SBs) were not changed. This alteration was not accompanied by a different capability to respond to in vitro oxidative challenge. No differences in the basal levels of DNA damage in polymorphonuclear leukocytes were found between patients and healthy subjects. Thus, this study supports the hypothesis that in vitiligo a systemic oxidative stress exists, and demonstrates for the first time the presence of oxidative alterations at the nuclear level. The increase in oxidative DNA damage shown in the mononuclear component of peripheral blood leukocytes from vitiligo patients was not particularly severe. However, these findings support an adjuvant role of antioxidant treatment in vitiligo

  15. AFFINITY BIOSENSOR BASED ON SCREEN-PRINTED ELECTRODE MODIFIED WITH DNA FOR GENOTOXIC COMPOUNDS DETECTION

    Bambang Kuswandi

    2010-06-01

    Full Text Available An electrochemical method for the detection of the genotoxic compounds using a DNA-modified electrode was developed. This electrode was successfully used for the electrochemical detection of genotoxic compounds in water samples. The electrochemical results clearly demonstrated that, the development is related to the molecular interaction between the surface-linked DNA obtained from calf thymus and the target compounds, such as pollutants, in order to develop a simple device for rapid screening of genotoxic compounds in environmental samples. The detection of such compounds was measured by their effect on the oxidation signal of the guanine peak of the DNA immobilised on the surface of carbon based Screen-Printed Electrode (SPE in disposable mode, and monitored by square-wave voltametric analysis. The DNA biosensor is able to detect known intercalating and groove-binding genotoxic compounds such as Dioxin, Bisphenol A, PCBs, and Phtalates. Application to real water samples is discussed and reported.   Keywords: electrochemical, screen-printed electrode, DNA biosensor, genotoxic compounds

  16. Oxidative DNA as related to cancer and aging

    Ames, B.N.

    1987-01-01

    DNA damage in man can result from a variety of endogenous processes. Of particular importance as endogenous processes may be metabolic pathways that generate oxygen radicals and other reactive oxygen species. Oxygen radicals have been shown to produce DNA base damage and strand breaks. Two products that are formed in DNA in vitro by chemical oxidation or ionizing radiation (and oxidative mutagen) are thymine glycol and hydroxymethyl-uracil, both oxidation products of thymine. Specific mammalian DNA repair systems are known to excise these lesions from DNA in vitro. The authors' laboratory has recently reported the identification, in both human and rat urine, of thymine glycol, thymidine glycol, and hydroxymethyluracil. They now have considerable evidence that these products are derived from the repair of oxidized DNA. The total output of these three compounds represents the formation of about 1,000 oxidized thymine residues per cell per day in man. Since these products are only three of a considerable number of types of oxidative DNA damage products described by radiobiologists, there are likely to be several thousand oxidative DNA hits per cell per day in man. Rats, which have a higher specific metabolic rate and a shorter life span, excrete about 15 times more thymine glycol, thymidine glycol, and hydroxymethyluracil per kilogram body weight. The authors also describe new methods for measuring the levels, which are considerable, of hydrogen peroxide and lipid hydroperoxides in normal plasma and tissues. These non-invasive assays of DNA and other oxidation products may allow the direct testing of current theories that relate oxidative metabolism to the processes of cancer and aging in man

  17. DNA enrichment approaches to identify unauthorized genetically modified organisms (GMOs).

    Arulandhu, Alfred J; van Dijk, Jeroen P; Dobnik, David; Holst-Jensen, Arne; Shi, Jianxin; Zel, Jana; Kok, Esther J

    2016-07-01

    With the increased global production of different genetically modified (GM) plant varieties, chances increase that unauthorized GM organisms (UGMOs) may enter the food chain. At the same time, the detection of UGMOs is a challenging task because of the limited sequence information that will generally be available. PCR-based methods are available to detect and quantify known UGMOs in specific cases. If this approach is not feasible, DNA enrichment of the unknown adjacent sequences of known GMO elements is one way to detect the presence of UGMOs in a food or feed product. These enrichment approaches are also known as chromosome walking or gene walking (GW). In recent years, enrichment approaches have been coupled with next generation sequencing (NGS) analysis and implemented in, amongst others, the medical and microbiological fields. The present review will provide an overview of these approaches and an evaluation of their applicability in the identification of UGMOs in complex food or feed samples.

  18. Explosive compaction of aluminum oxide modified by multiwall carbon nanotubes

    Buzyurkin, A. E.; Kraus, E. I.; Lukyanov, Ya L.

    2018-04-01

    This paper presents experiments and numerical research on explosive compaction of aluminum oxide powder modified by multiwall carbon nanotubes (MWCNT) and modeling of the stress state behind the shock front at shock loading. The aim of this study was to obtain a durable low-porosity compact sample. The explosive compaction technology is used in this problem because the aluminum oxide is an extremely hard and refractory material. Therefore, its compaction by traditional methods requires special equipment and considerable expenses.

  19. Investigation of properties of modified oxides structured by nano technology

    Kurina, I.S.; Serebrennikova, O.V.; Rumyantsev, V.N.; Dvoryashin, A.M.

    2009-01-01

    Research results on the PuO 2 +MgO fuel composition with CeO 2 as a PuO 2 simulator are presented. The water nano technology for the production of oxide ceramic materials, developed in IPPE, was used for fabrication of powders and modified pellets. This technology includes obtaining precipitate, consisting of particles of different sizes as well as of nanoparticles, which is further calcined, pressed and sintered. It results in modifying structure of the sintered pellets. Modified pellets have anomalously high thermal conductivity measured by the axial heat flux method [ru

  20. Thermal oxidative degradation of wood modified with aminophenylborates

    Klyachenkova Olga

    2016-01-01

    Full Text Available Comparative thermal analysis in the presence of oxygen was carried out for samples of native pine wood and wood samples modified with aminophenylborates. Significant decrease in the amount of heat released during thermal decomposition of the modified samples was established, which is due to the increase of carbonaceous residues on the surface. Reduction of heat release during decomposition of the modified samples may be explained by the lower yield of combustible volatile products as well as by thin film of boron oxide, formed on the surface of the modified wood, that partially reflects heat flow. Produced upon the modifier decomposition water vapor and inert nitrogen oxides dilute gaseous mixture near the wood surface and isolate it from oxygen. This enhances fire-resistance of wood modified with mono- and diethanolamine(N→Bphenylborates. Hydroxyl group at the sixth carbon atom of the glucopyranose ring of cellulose participates in reactions of cellulose modification, which prevents formation of flammable levoglucosan and, consequently, improves the fire-resistance of the modified wood.

  1. Selective detection and quantification of modified DNA with solid-state nanopores.

    Carlsen, Autumn T; Zahid, Osama K; Ruzicka, Jan A; Taylor, Ethan W; Hall, Adam R

    2014-10-08

    We demonstrate a solid-state nanopore assay for the unambiguous discrimination and quantification of modified DNA. Individual streptavidin proteins are employed as high-affinity tags for DNA containing a single biotin moiety. We establish that the rate of translocation events corresponds directly to relative concentration of protein-DNA complexes and use the selectivity of our approach to quantify modified oligonucleotides from among a background of unmodified DNA in solution.

  2. DNA Mismatch Repair and Oxidative DNA Damage: Implications for Cancer Biology and Treatment

    Bridge, Gemma; Rashid, Sukaina; Martin, Sarah A.

    2014-01-01

    Many components of the cell, including lipids, proteins and both nuclear and mitochondrial DNA, are vulnerable to deleterious modifications caused by reactive oxygen species. If not repaired, oxidative DNA damage can lead to disease-causing mutations, such as in cancer. Base excision repair and nucleotide excision repair are the two DNA repair pathways believed to orchestrate the removal of oxidative lesions. However, recent findings suggest that the mismatch repair pathway may also be important for the response to oxidative DNA damage. This is particularly relevant in cancer where mismatch repair genes are frequently mutated or epigenetically silenced. In this review we explore how the regulation of oxidative DNA damage by mismatch repair proteins may impact on carcinogenesis. We discuss recent studies that identify potential new treatments for mismatch repair deficient tumours, which exploit this non-canonical role of mismatch repair using synthetic lethal targeting

  3. DNA Mismatch Repair and Oxidative DNA Damage: Implications for Cancer Biology and Treatment

    Bridge, Gemma; Rashid, Sukaina; Martin, Sarah A., E-mail: sarah.martin@qmul.ac.uk [Centre for Molecular Oncology, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ (United Kingdom)

    2014-08-05

    Many components of the cell, including lipids, proteins and both nuclear and mitochondrial DNA, are vulnerable to deleterious modifications caused by reactive oxygen species. If not repaired, oxidative DNA damage can lead to disease-causing mutations, such as in cancer. Base excision repair and nucleotide excision repair are the two DNA repair pathways believed to orchestrate the removal of oxidative lesions. However, recent findings suggest that the mismatch repair pathway may also be important for the response to oxidative DNA damage. This is particularly relevant in cancer where mismatch repair genes are frequently mutated or epigenetically silenced. In this review we explore how the regulation of oxidative DNA damage by mismatch repair proteins may impact on carcinogenesis. We discuss recent studies that identify potential new treatments for mismatch repair deficient tumours, which exploit this non-canonical role of mismatch repair using synthetic lethal targeting.

  4. Oxidatively generated DNA/RNA damage in psychological stress states

    Jørgensen, Anders

    2013-01-01

    age-related somatic disorders. The overall aim of the PhD project was to investigate the relation between psychopathology, psychological stress, stress hormone secretion and oxidatively generated DNA and RNA damage, as measured by the urinary excretion of markers of whole-body DNA/RNA oxidation (8...... between the 24 h urinary cortisol excretion and the excretion of 8-oxodG/8-oxoGuo, determined in the same samples. Collectively, the studies could not confirm an association between psychological stress and oxidative stress on nucleic acids. Systemic oxidatively generated DNA/RNA damage was increased......Both non-pathological psychological stress states and mental disorders are associated with molecular, cellular and epidemiological signs of accelerated aging. Oxidative stress on nucleic acids is a critical component of cellular and organismal aging, and a suggested pathogenic mechanism in several...

  5. Role of oxidative DNA damage in genome instability and cancer

    Bignami, M.; Kunkel, T.

    2009-01-01

    Inactivation of mismatch repair (MMR) is associated with a dramatic genomic instability that is observed experimentally as a mutator phenotype and micro satellite instability (MSI). It has been implicit that the massive genetic instability in MMR defective cells simply reflects the accumulation of spontaneous DNA polymerase errors during DNA replication. We recently identified oxidation damage, a common threat to DNA integrity to which purines are very susceptible, as an important cofactor in this genetic instability

  6. DNA immobilization on polymer-modified Si surface by controlling pH

    Demirel, Goekcen Birlik; Caykara, Tuncer

    2009-01-01

    A novel approach based on polymer-modified Si surface as DNA sensor platforms is presented. The polymer-modified Si surface was prepared by using 3-(methacryloxypropyl)trimethoxysilane [γ-MPS] and poly(acrylamide) [PAAm]. Firstly, a layer of γ-MPS was formed on the hydroxylated silicon surface as a monolayer and then modified with different molecular weight of PAAm to form polymer-modified surface. The polymer-modified Si surface was used for dsDNA immobilization. All steps about formation of layer structure were characterized by ellipsometry, atomic force microscopy (AFM), attenuated total reflectance Fourier transformed infrared (ATR-FTIR), and contact angle (CA) measurements. We found that in this case the amount of dsDNA immobilized onto the surface was dictated by the electrostatic interaction between the substrate surface and the DNA. Our results thus demonstrated that DNA molecules could be immobilized differently onto the polymer-modified support surface via electrostatic interactions.

  7. Asbestos induced oxidative injury to DNA.

    Mahmood, N; Khan, S G; Ali, S; Athar, M; Rahman, Q

    1993-06-01

    DNA-damaging effects of asbestos in the presence of organic peroxides and hydroperoxides were investigated. The destabilization of the secondary structure of DNA, damage to deoxyribose sugar and DNA fidelity were measured, respectively, by S-1 nuclease hydrolysis, the formation of thiobarbituric acid (TBA)-reacting species and a melting temperature (Tm) profile using calf thymus DNA. S-1 nuclease hydrolysis and Tm determinations have shown that the presence of benzoylperoxide (BOOB), cumene hydroperoxide (COOH) or tertiary-butyl hydroperoxide (t-BOOH) increased asbestos-mediated DNA damage by a large factor compared either to asbestos alone or to peroxide or hydroperoxide alone. However, no formation of TBA-reacting species could be observed in this system. The quenchers of reactive oxygen species (ROS) afforded protection against DNA damage. These results suggest that asbestos in the presence of organic peroxides and hydroperoxides damage the DNA which is mediated by the generation of oxygen free radicals. The significance of these results in relation to the development of cancer of the respiratory tract among the asbestos exposed population is discussed.

  8. DNA-modified electrodes (Ⅶ)——Preparation and characterization of DNA-bonded and DNA-adsorbed SAM/Au electrodes

    陆琪; 庞代文; 胡深; 程介克; 蔡雄伟; 施财辉; 毛秉伟; 戴鸿平

    1999-01-01

    Two kinds of DNA-modified electrodes were prepared by covalent and adsorptive immobilization of DNA onto self-assembled monolayers of 2, 2’-dithiodiethanol on gold electrodes and characterized by cyclic voltammetry, Xray photoelectron spectroscopy and scanning tunneling microscopy. The results suggest that the methods are satisfactory for the immobilization of DNA on electrodes.

  9. One-electron oxidation of DNA: mechanism and consequences.

    Schuster, Gary B

    2009-01-01

    All living organisms store the information necessary to maintain life in their DNA. Any process that damages DNA and causes loss or corruption of that information threatens the viability of the organism. One-electron oxidation is such a process. Loss of an electron from DNA generates a radical cation that is located primarily on its nucleobases. The radical cation migrates reversibly through duplex DNA by hopping until it is eventually trapped in an irreversible chemical reaction. The particular sequence of nucleobases in a DNA oligomer determines both the efficiency of hopping and the specific location and nature of the damaging chemical reaction. In its normal aqueous solutions, DNA is a polyanion because of the negative charge carried by its phosphate groups. Counter ions (typically Na(+)) to the phosphate groups play an important role in facilitating both the migration of the radical cation and in its eventual reaction with H(2)O. Irreversible reaction of a radical cation with H(2)O in duplex DNA occurs preferentially at the most reactive site. In normal DNA that is comprised of the four common DNA nucleobases, reaction occurs most commonly at a guanine and results in its conversion primarily to 8-oxo-7,8-dihydroguanine (8-OxoG). Both electronic and steric effects control the outcome of this process. If the DNA oligomer does not contain a suitable guanine, then reaction of the radical cation occurs at the thymine of a TT step primarily by a tandem process. The general outcomes revealed in the one-electron oxidation of DNA oligomers in solution appear to be generally valid also for more complex DNA structures and for the cellular DNA of living organisms.

  10. Modifying and adapting a plant-based DNA extraction protocol for ...

    ... a 100 apparently healthy individuals residing in Calabar. The modified DNA procedure yielded good quality genomic DNA which was used in carrying out allele specific polymerase chain reaction which also yielded good quality amplicons. This method is simple and suitable for the extraction of DNA from human red cell.

  11. Dietary Berries and Ellagic Acid Prevent Oxidative DNA Damage and Modulate Expression of DNA Repair Genes

    Ramesh C. Gupta

    2008-03-01

    Full Text Available DNA damage is a pre-requisite for the initiation of cancer and agents that reduce this damage are useful in cancer prevention. In this study, we evaluated the ability of whole berries and berry phytochemical, ellagic acid to reduce endogenous oxidative DNA damage. Ellagic acid was selected based on > 95% inhibition of 8-oxodeoxyguosine (8-oxodG and other unidentified oxidative DNA adducts induced by 4-hydroxy-17B;-estradiol and CuCl2 in vitro. Inhibition of the latter occurred at lower concentrations (10 u(microM than that for 8-oxodG (100 u(microM. In the in vivo study, female CD-1 mice (n=6 were fed either a control diet or diet supplemented with ellagic acid (400 ppm and dehydrated berries (5% w/w with varying ellagic acid contents -- blueberry (low, strawberry (medium and red raspberry (high, for 3 weeks. Blueberry and strawberry diets showed moderate reductions in endogenous DNA adducts (25%. However, both red raspberry and ellagic acid diets showed a significant reduction of 59% (p < 0.001 and 48% (p < 0.01, respectively. Both diets also resulted in a 3-8 fold over-expression of genes involved in DNA repair such as xeroderma pigmentosum group A complementing protein (XPA, DNA excision repair protein (ERCC5 and DNA ligase III (DNL3. These results suggest that red raspberry and ellagic acid reduce endogenous oxidative DNA damage by mechanisms which may involve increase in DNA repair.

  12. Oxidative DNA damage during sleep periods among nightshift workers.

    Bhatti, Parveen; Mirick, Dana K; Randolph, Timothy W; Gong, Jicheng; Buchanan, Diana Taibi; Zhang, Junfeng Jim; Davis, Scott

    2016-08-01

    Oxidative DNA damage may be increased among nightshift workers because of suppression of melatonin, a cellular antioxidant, and/or inflammation related to sleep disruption. However, oxidative DNA damage has received limited attention in previous studies of nightshift work. From two previous cross-sectional studies, urine samples collected during a night sleep period for 217 dayshift workers and during day and night sleep (on their first day off) periods for 223 nightshift workers were assayed for 8-hydroxydeoxyguanosine (8-OH-dG), a marker of oxidative DNA damage, using high-performance liquid chromatography with electrochemical detection. Urinary measures of 6-sulfatoxymelatonin (aMT6s), a marker of circulating melatonin levels, and actigraphy-based sleep quality data were also available. Nightshift workers during their day sleep periods excreted 83% (p=0.2) and 77% (p=0.03) of the 8-OH-dG that dayshift workers and they themselves, respectively, excreted during their night sleep periods. Among nightshift workers, higher aMT6s levels were associated with higher urinary 8-OH-dG levels, and an inverse U-shaped trend was observed between 8-OH-dG levels and sleep efficiency and sleep duration. Reduced excretion of 8-OH-dG among nightshift workers during day sleep may reflect reduced functioning of DNA repair machinery, which could potentially lead to increased cellular levels of oxidative DNA damage. Melatonin disruption among nightshift workers may be responsible for the observed effect, as melatonin is known to enhance repair of oxidative DNA damage. Quality of sleep may similarly impact DNA repair. Cellular levels of DNA damage will need to be evaluated in future studies to help interpret these findings. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  13. Cobalt oxide nanoparticle-modified carbon nanotubes as an ...

    of 60 mV were observed at. 100 mV s. −1 for CoOx−MWNT/GCE. An anodic peak at. 100 mV attributed to Co(II)/Co(III) redox transition associated with the electrode surface. The cathodic peak at 20 mV corre- spond to the reduction of various cobalt oxide species formed during the anodic sweep. The stability of the modified ...

  14. Acute hypoxia and hypoxic exercise induce DNA strand breaks and oxidative DNA damage in humans

    Møller, P; Loft, S; Lundby, C

    2001-01-01

    ; lymphocytes were isolated for analysis of DNA strand breaks and oxidatively altered nucleotides, detected by endonuclease III and formamidipyridine glycosylase (FPG) enzymes. Urine was collected for 24 h periods for analysis of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), a marker of oxidative DNA damage...... oxygen species, generated by leakage of the mitochondrial respiration or during a hypoxia-induced inflammation. Furthermore, the presence of DNA strand breaks may play an important role in maintaining hypoxia-induced inflammation processes. Hypoxia seems to deplete the antioxidant system of its capacity...

  15. DNA-modified electrodes fabricated using copper-free click chemistry for enhanced protein detection.

    Furst, Ariel L; Hill, Michael G; Barton, Jacqueline K

    2013-12-31

    A method of DNA monolayer formation has been developed using copper-free click chemistry that yields enhanced surface homogeneity and enables variation in the amount of DNA assembled; extremely low-density DNA monolayers, with as little as 5% of the monolayer being DNA, have been formed. These DNA-modified electrodes (DMEs) were characterized visually, with AFM, and electrochemically, and were found to facilitate DNA-mediated reduction of a distally bound redox probe. These low-density monolayers were found to be more homogeneous than traditional thiol-modified DNA monolayers, with greater helix accessibility through an increased surface area-to-volume ratio. Protein binding efficiency of the transcriptional activator TATA-binding protein (TBP) was also investigated on these surfaces and compared to that on DNA monolayers formed with standard thiol-modified DNA. Our low-density monolayers were found to be extremely sensitive to TBP binding, with a signal decrease in excess of 75% for 150 nM protein. This protein was detectable at 4 nM, on the order of its dissociation constant, with our low-density monolayers. The improved DNA helix accessibility and sensitivity of our low-density DNA monolayers to TBP binding reflects the general utility of this method of DNA monolayer formation for DNA-based electrochemical sensor development.

  16. OXIDATIVE DNA DAMAGE IN DIESEL BUS MECHANICS

    Rationale: Diesel exposure has been associated with adverse health effects, including susceptibility to asthma, allergy and cancer. Previous epidemiological studies demonstrated increased cancer incidence among workers exposed to diesel. This is likely due to oxid...

  17. Synthesis of adenine-modified reduced graphene oxide nanosheets.

    Cao, Huaqiang; Wu, Xiaoming; Yin, Gui; Warner, Jamie H

    2012-03-05

    We report here a facile strategy to synthesize the nanocomposite of adenine-modified reduced graphene oxide (AMG) via reaction between adenine and GOCl which is generated from SOCl(2) reacted with graphite oxide (GO). The as-synthesized AMG was characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), UV-vis absorption spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and galvanostatic discharge analysis. The AMG owns about one adenine group per 53 carbon atoms on a graphene sheet, which improves electronic conductivity compared with reduced graphene oxide (RGO). The AMG displays enhanced supercapacitor performance compared with RGO accompanying good stability and good cycling behavior in the supercapacitor.

  18. Comparison of impedimetric detection of DNA hybridization on the various biosensors based on modified glassy carbon electrodes with PANHS and nanomaterials of RGO and MWCNTs.

    Benvidi, Ali; Tezerjani, Marzieh Dehghan; Jahanbani, Shahriar; Mazloum Ardakani, Mohammad; Moshtaghioun, Seyed Mohammad

    2016-01-15

    In this research, we have developed lable free DNA biosensors based on modified glassy carbon electrodes (GCE) with reduced graphene oxide (RGO) and carbon nanotubes (MWCNTs) for detection of DNA sequences. This paper compares the detection of BRCA1 5382insC mutation using independent glassy carbon electrodes (GCE) modified with RGO and MWCNTs. A probe (BRCA1 5382insC mutation detection (ssDNA)) was then immobilized on the modified electrodes for a specific time. The immobilization of the probe and its hybridization with the target DNA (Complementary DNA) were performed under optimum conditions using different electrochemical techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The proposed biosensors were used for determination of complementary DNA sequences. The non-modified DNA biosensor (1-pyrenebutyric acid-N- hydroxysuccinimide ester (PANHS)/GCE), revealed a linear relationship between ∆Rct and logarithm of the complementary target DNA concentration ranging from 1.0×10(-16)molL(-1) to 1.0×10(-10)mol L(-1) with a correlation coefficient of 0.992, for DNA biosensors modified with multi-wall carbon nanotubes (MWCNTs) and reduced graphene oxide (RGO) wider linear range and lower detection limit were obtained. For ssDNA/PANHS/MWCNTs/GCE a linear range 1.0×10(-17)mol L(-1)-1.0×10(-10)mol L(-1) with a correlation coefficient of 0.993 and for ssDNA/PANHS/RGO/GCE a linear range from 1.0×10(-18)mol L(-1) to 1.0×10(-10)mol L(-1) with a correlation coefficient of 0.985 were obtained. In addition, the mentioned biosensors were satisfactorily applied for discriminating of complementary sequences from noncomplementary sequences, so the mentioned biosensors can be used for the detection of BRCA1-associated breast cancer. Copyright © 2015. Published by Elsevier B.V.

  19. Oxidative DNA damage causes mitochondrial genomic instability in Saccharomyces cerevisiae.

    Doudican, Nicole A; Song, Binwei; Shadel, Gerald S; Doetsch, Paul W

    2005-06-01

    Mitochondria contain their own genome, the integrity of which is required for normal cellular energy metabolism. Reactive oxygen species (ROS) produced by normal mitochondrial respiration can damage cellular macromolecules, including mitochondrial DNA (mtDNA), and have been implicated in degenerative diseases, cancer, and aging. We developed strategies to elevate mitochondrial oxidative stress by exposure to antimycin and H(2)O(2) or utilizing mutants lacking mitochondrial superoxide dismutase (sod2Delta). Experiments were conducted with strains compromised in mitochondrial base excision repair (ntg1Delta) and oxidative damage resistance (pif1Delta) in order to delineate the relationship between these pathways. We observed enhanced ROS production, resulting in a direct increase in oxidative mtDNA damage and mutagenesis. Repair-deficient mutants exposed to oxidative stress conditions exhibited profound genomic instability. Elimination of Ntg1p and Pif1p resulted in a synergistic corruption of respiratory competency upon exposure to antimycin and H(2)O(2). Mitochondrial genomic integrity was substantially compromised in ntg1Delta pif1Delta sod2Delta strains, since these cells exhibit a total loss of mtDNA. A stable respiration-defective strain, possessing a normal complement of mtDNA damage resistance pathways, exhibited a complete loss of mtDNA upon exposure to antimycin and H(2)O(2). This loss was preventable by Sod2p overexpression. These results provide direct evidence that oxidative mtDNA damage can be a major contributor to mitochondrial genomic instability and demonstrate cooperation of Ntg1p and Pif1p to resist the introduction of lesions into the mitochondrial genome.

  20. Global DNA methylation and oxidative stress biomarkers in workers exposed to metal oxide nanoparticles

    Liou, Saou-Hsing; Wu, Wei-Te; Liao, Hui-Yi [National Institute of Environmental Health Sciences, National Health Research Institutes, Zhunan, Miaoli County, Taiwan (China); Chen, Chao-Yu; Tsai, Cheng-Yen; Jung, Wei-Ting [Department of Chemistry, Fu Jen Catholic University, New Taipei City, Taiwan (China); Lee, Hui-Ling, E-mail: huilinglee3573@gmail.com [Department of Chemistry, Fu Jen Catholic University, New Taipei City, Taiwan (China)

    2017-06-05

    Highlights: • Global methylation and oxidative DNA damage levels in nanomaterial handling workers were assessed. • 8-isoprostane in exhaled breath condensate of workers exposed to nanoparticles was higher. • 8-OHdG was negatively correlated with global methylation. • Exposure to metal oxide nanoparticles may lead to global methylation and DNA oxidative damage. - Abstract: This is the first study to assess global methylation, oxidative DNA damage, and lipid peroxidation in workers with occupational exposure to metal oxide nanomaterials (NMs). Urinary and white blood cell (WBC) 8-hydroxydeoxyguanosine (8-OHdG), and exhaled breath condensate (EBC) 8-isoprostane were measured as oxidative stress biomarkers. WBC global methylation was measured as an epigenetic alteration. Exposure to TiO{sub 2}, SiO{sub 2,} and indium tin oxide (ITO) resulted in significantly higher oxidative biomarkers such as urinary 8-OHdG and EBC 8-isoprostane. However, significantly higher WBC 8-OHdG and lower global methylation were only observed in ITO handling workers. Significant positive correlations were noted between WBC and urinary 8-OHdG (Spearman correlation r = 0.256, p = 0.003). Furthermore, a significant negative correlation was found between WBC 8-OHdG and global methylation (r = −0.272, p = 0.002). These results suggest that exposure to metal oxide NMs may lead to global methylation, DNA oxidative damage, and lipid peroxidation.

  1. Preferential recognition of auto-antibodies against 4-hydroxynonenal modified DNA in the cancer patients.

    Faisal, Mohammad; Shahab, Uzma; Alatar, Abdulrahman A; Ahmad, Saheem

    2017-11-01

    The structural perturbations in DNA molecule may be caused by a break in a strand, a missing base from the backbone, or a chemically changed base. These alterations in DNA that occurs naturally can result from metabolic or hydrolytic processes. DNA damage plays a major role in the mutagenesis, carcinogenesis, aging and various other patho-physiological conditions. DNA damage can be induced through hydrolysis, exposure to reactive oxygen species (ROS) and other reactive carbonyl metabolites including 4-hydroxynonenal (HNE). 4-HNE is an important lipid peroxidation product which has been implicated in the mutagenesis and carcinogenesis processes. The present study examines to probe the presence of auto-antibodies against 4-hydroxynonenal damaged DNA (HNE-DNA) in various cancer subjects. In this study, the purified calf thymus DNA was damaged by the action of 4-HNE. The DNA was incubated with 4-HNE for 24 h at 37°C temperature. The binding characteristics of cancer auto-antibodies were assessed by direct binding and competitive inhibition ELISA. DNA modifications produced hyperchromicity in UV spectrum and decreased fluorescence intensity. Cancer sera exhibited enhanced binding with the 4-HNE modified calf thymus DNA as compared to its native conformer. The 4-HNE modified DNA presents unique epitopes which may be one of the factors for the auto-antibody induction in cancer patients. The HNE modified DNA presents unique epitopes which may be one of the factors for the autoantibody induction in cancer patients. © 2017 Wiley Periodicals, Inc.

  2. Detection of DNA of genetically modified maize by a silicon nanowire field-effect transistor

    Pham, Van Binh; Tung Pham, Xuan Thanh; Duong Dang, Ngoc Thuy; Tuyen Le, Thi Thanh; Tran, Phu Duy; Nguyen, Thanh Chien; Nguyen, Van Quoc; Dang, Mau Chien; Tong, Duy Hien; Van Rijn, Cees J M

    2011-01-01

    A silicon nanowire field-effect transistor based sensor (SiNW-FET) has been proved to be the most sensitive and powerful device for bio-detection applications. In this paper, SiNWs were first fabricated by using our recently developed deposition and etching under angle technique (DEA), then used to build up the complete SiNW device based biosensor. The fabricated SiNW biosensor was used to detect DNA of genetically modified maize. As the DNA of the genetically modified maize has particular DNA sequences of 35S promoter, we therefore designed 21 mer DNA oligonucleotides, which are used as a receptor to capture the transferred DNA of maize. In our work, the SiNW biosensor could detect DNA of genetically modified maize with concentrations down to about 200 pM

  3. Repair of oxidative DNA damage by amino acids.

    Milligan, J R; Aguilera, J A; Ly, A; Tran, N Q; Hoang, O; Ward, J F

    2003-11-01

    Guanyl radicals, the product of the removal of a single electron from guanine, are produced in DNA by the direct effect of ionizing radiation. We have produced guanyl radicals in DNA by using the single electron oxidizing agent (SCN)2-, itself derived from the indirect effect of ionizing radiation via thiocyanate scavenging of OH. We have examined the reactivity of guanyl radicals in plasmid DNA with the six most easily oxidized amino acids cysteine, cystine, histidine, methionine, tryptophan and tyrosine and also simple ester and amide derivatives of them. Cystine and histidine derivatives are unreactive. Cysteine, methionine, tyrosine and particularly tryptophan derivatives react to repair guanyl radicals in plasmid DNA with rate constants in the region of approximately 10(5), 10(5), 10(6) and 10(7) dm3 mol(-1) s(-1), respectively. The implication is that amino acid residues in DNA binding proteins such as histones might be able to repair by an electron transfer reaction the DNA damage produced by the direct effect of ionizing radiation or by other oxidative insults.

  4. Oxidative Stress and DNA Methylation in Prostate Cancer

    Krishna Vanaja Donkena

    2010-01-01

    Full Text Available The protective effects of fruits, vegetables, and other foods on prostate cancer may be due to their antioxidant properties. An imbalance in the oxidative stress/antioxidant status is observed in prostate cancer patients. Genome oxidative damage in prostate cancer patients is associated with higher lipid peroxidation and lower antioxidant levels. Oxygen radicals are associated with different steps of carcinogenesis, including structural DNA damage, epigenetic changes, and protein and lipid alterations. Epigenetics affects genetic regulation, cellular differentiation, embryology, aging, cancer, and other diseases. DNA methylation is perhaps the most extensively studied epigenetic modification, which plays an important role in the regulation of gene expression and chromatin architecture, in association with histone modification and other chromatin-associated proteins. This review will provide a broad overview of the interplay of oxidative stress and DNA methylation, DNA methylation changes in regulation of gene expression, lifestyle changes for prostate cancer prevention, DNA methylation as biomarkers for prostate cancer, methods for detection of methylation, and clinical application of DNA methylation inhibitors for epigenetic therapy.

  5. Highly sensitive DNA sensors based on cerium oxide nanorods

    Nguyet, Nguyen Thi; Hai Yen, Le Thi; Van Thu, Vu; lan, Hoang; Trung, Tran; Vuong, Pham Hung; Tam, Phuong Dinh

    2018-04-01

    In this work, a CeO2 nanorod (NR)-based electrochemical DNA sensor was developed to identify Salmonella that causes food-borne infections. CeO2 NRs were synthesized without templates via a simple and unexpensive hydrothermal approach at 170 °C for 12 h by using CeO(NO3)3·6H2O as a Ce source. The DNA probe was immobilized onto the CeO2 NR-modified electrode through covalent attachment. The characteristics of the hybridized DNA were analyzed through electrochemical impedance spectroscopy (EIS) with [Fe(CN)6]3-/4- as a redox probe. Experimental results showed that electron transfer resistance (Ret) increased after the DNA probe was attached to the electrode surface and increased further after the DNA probe hybridized with its complementary sequence. A linear response of Ret to the target DNA concentration was found from 0.01 μM to 2 μM. The detection limit and sensitivity of the DNA sensor were 0.01 μM and 3362.1 Ω μM-1 cm-2, respectively. Various parameters, such as pH value, ionic strength, DNA probe concentration, and hybridization time, influencing DNA sensor responses were also investigated.

  6. Increased systemic oxidatively generated DNA and RNA damage in schizophrenia

    Jørgensen, Anders; Brødbæk, Kasper; Fink-Jensen, Anders

    2013-01-01

    such as cardiovascular disease, type 2 diabetes and dementia. We determined the urinary excretion of markers of systemic Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA) oxidation, 8-oxo-7,8-dihydro-2'-deoxyguanosine and 8-oxo-7,8-dihydroguanosine, respectively, in 40 schizophrenia patients and 40 age- and sex...

  7. Biomarkers of oxidative damage to DNA and repair

    Loft, Steffen; Høgh Danielsen, Pernille; Mikkelsen, Lone

    2008-01-01

    environmental factors, including particulate air pollution, cause oxidative damage to DNA, whereas diets rich in fruit and vegetables or antioxidant supplements may reduce the levels and enhance repair. Urinary excretion of 8-oxodG, genotype and expression of OGG1 have been associated with risk of cancer...

  8. Cancer risk and oxidative DNA damage in man

    Loft, S; Poulsen, H E

    1996-01-01

    with a mechanistically based increased risk of cancer, including Fanconi anemia, chronic hepatitis, cystic fibrosis, and various autoimmune diseases, the biomarker studies indicate an increased rate of oxidative DNA damage or in some instances deficient repair. Human studies support the experimentally based notion...

  9. Altered DNA repair, oxidative stress and antioxidant status

    Coronary artery disease (CAD) is a multifactorial disease caused by the interplay of environmental risk factors with multiple predisposing genes. The present study was undertaken to evaluate the role of DNA repair efficiency and oxidative stress and antioxidant status in CAD patients. Malonaldehyde (MDA), which is an ...

  10. Antimicrobial effects of zinc oxide nanoparticles modified with silver

    Lopes, Rayssa Souza; Arantes, Tatiane Moraes

    2016-01-01

    Full text: With the emergence of resistant microbial organisms to multiple antibiotics, different shapes of silver nanoparticles are among the most promising antimicrobial agents that have been developed from nanotechnology. Besides the silver nanoparticles oxide nanoparticles such as zinc oxide (ZnO) is gaining prominence due to its bactericidal properties. [1-3]. Thus, this study aims to develop biomaterials from zinc oxide nanoparticles modified with silver with antimicrobial properties. The ZnO nanoparticles were synthesized by hydrothermal processing by alkaline hydrolysis zinc acetate. Colloidal dispersions of silver nanoparticles were synthesized by the Turkevich method using sodium citrate to reduce silver nitrate at high pH and at 90 °C in the presence of zinc oxide nanoparticles. Both nanoparticles were characterized by X-ray diffraction (XRD), FTIR and Raman spectroscopy and scanning electron microscopy (SEM). The XRD and Raman spectra showed crystalline ZnO colloidal nanoparticles were obtained in the hexagonal phase. XRD measure showed cubic silver diffraction peaks cubic phase confirmed the presence of the silver nanoparticles decorated zinc oxide nanoparticles. SEM images showed ZnO nanoparticles presented a nanorod shapes with length around 80 nm decorated with spherical silver nanoparticles about 20 nm in diameter The results showed that crystalline zinc oxide colloidal nanoparticles with rod-like morphology and uniform decorated with silver spherical nanoparticles size were obtained by hydrothermal synthesis. Results of antibacterial tests indicate that the ZnO/Ag nanoparticles have antibacterial properties against both Staphylococcus aureus and Escherichia coli. The results demonstrated that the ZnO/Ag nanoparticles have potential use as biomaterials in medical/odontological applications. (author)

  11. Antimicrobial effects of zinc oxide nanoparticles modified with silver

    Lopes, Rayssa Souza; Arantes, Tatiane Moraes, E-mail: rayssasouza.net@gmail.com [Universidade Federal de Goias (UFG), Goiania (Brazil)

    2016-07-01

    Full text: With the emergence of resistant microbial organisms to multiple antibiotics, different shapes of silver nanoparticles are among the most promising antimicrobial agents that have been developed from nanotechnology. Besides the silver nanoparticles oxide nanoparticles such as zinc oxide (ZnO) is gaining prominence due to its bactericidal properties. [1-3]. Thus, this study aims to develop biomaterials from zinc oxide nanoparticles modified with silver with antimicrobial properties. The ZnO nanoparticles were synthesized by hydrothermal processing by alkaline hydrolysis zinc acetate. Colloidal dispersions of silver nanoparticles were synthesized by the Turkevich method using sodium citrate to reduce silver nitrate at high pH and at 90 °C in the presence of zinc oxide nanoparticles. Both nanoparticles were characterized by X-ray diffraction (XRD), FTIR and Raman spectroscopy and scanning electron microscopy (SEM). The XRD and Raman spectra showed crystalline ZnO colloidal nanoparticles were obtained in the hexagonal phase. XRD measure showed cubic silver diffraction peaks cubic phase confirmed the presence of the silver nanoparticles decorated zinc oxide nanoparticles. SEM images showed ZnO nanoparticles presented a nanorod shapes with length around 80 nm decorated with spherical silver nanoparticles about 20 nm in diameter The results showed that crystalline zinc oxide colloidal nanoparticles with rod-like morphology and uniform decorated with silver spherical nanoparticles size were obtained by hydrothermal synthesis. Results of antibacterial tests indicate that the ZnO/Ag nanoparticles have antibacterial properties against both Staphylococcus aureus and Escherichia coli. The results demonstrated that the ZnO/Ag nanoparticles have potential use as biomaterials in medical/odontological applications. (author)

  12. Effect of modified wuzi yanzong granule on patients with mild cognitive impairment from oxidative damage aspect.

    Wang, Xue-mei; Fu, Hong; Liu, Geng-xin; Zhu, Wei; Li, Li; Yang, Jin-xia

    2007-12-01

    To observe the effects of modified Wuzi Yanzong Granule (WYG) on memory function and the activity of serum superoxide dismutase (SOD), malondialdehyde (MDA) levels, leukocyte mitochondrial DNA (mtDNA) deletion rate and beta-amyloid protein(1-28) (A beta(1-28)) in patients with mild cognitive impairment (MCI). Thirty-six patients with MCI were selected based on the internationally recognized Petersen's criteria, and equally and randomly assigned to two groups. The treated group was treated with WYG and the control group was treated with placebo for 3 months. In addition, 20 healthy subjects were included in the study as the normal control group. Changes of memory function, SOD activity, MDA content, leukocyte mtDNA deletion rate and A beta(1-28) content were observed before and after treatment. Compared with the normal control group, the memory quotient and SOD activity in patients with MCI decreased significantly (P < 0.01), while MDA, A beta(1-28) levels and the leukocyte mtDNA deletion rate increased significantly (P < 0.01). After treatment, levels of memory quotient and serum SOD activity increased while the serum MDA level, leukocyte mtDNA deletion rate and A beta(1-28) level decreased in the treated group compared with those before treatment (P<0.01, P<0.05). Meanwhile, leukocyte mtDNA deletion rate and A beta(1-28) content in the treated group were all lower than those in the control group (P<0.05). WYG could improve memory function in patients with MCI and the therapeutic mechanism is possibly related to the increased activity of anti-oxidase, the improved free radical metabolism and the alleviation of leukocyte mtDNA oxidation damage. WYG shows clinical significance in delaying the progression of MCI.

  13. UVA-induced DNA double-strand breaks result from the repair of clustered oxidative DNA damages

    Greinert, R.; Volkmer, B.; Henning, S.; Breitbart, E. W.; Greulich, K. O.; Cardoso, M. C.; Rapp, Alexander

    2012-01-01

    UVA (320–400 nm) represents the main spectral component of solar UV radiation, induces pre-mutagenic DNA lesions and is classified as Class I carcinogen. Recently, discussion arose whether UVA induces DNA double-strand breaks (dsbs). Only few reports link the induction of dsbs to UVA exposure and the underlying mechanisms are poorly understood. Using the Comet-assay and γH2AX as markers for dsb formation, we demonstrate the dose-dependent dsb induction by UVA in G1-synchronized human keratinocytes (HaCaT) and primary human skin fibroblasts. The number of γH2AX foci increases when a UVA dose is applied in fractions (split dose), with a 2-h recovery period between fractions. The presence of the anti-oxidant Naringin reduces dsb formation significantly. Using an FPG-modified Comet-assay as well as warm and cold repair incubation, we show that dsbs arise partially during repair of bi-stranded, oxidative, clustered DNA lesions. We also demonstrate that on stretched chromatin fibres, 8-oxo-G and abasic sites occur in clusters. This suggests a replication-independent formation of UVA-induced dsbs through clustered single-strand breaks via locally generated reactive oxygen species. Since UVA is the main component of solar UV exposure and is used for artificial UV exposure, our results shine new light on the aetiology of skin cancer. PMID:22941639

  14. Modifiers of radiation action on DNA screened by analytical ultracentrifugation

    Cobreros, G.; Lopez Zumel, M.C.; Usobiaga, P.

    1982-01-01

    The effect of daunomycin, chromomycin A 3 , anthramycin, cis-dichlorodiammineplatinum(II) (cisplatin), mitomycin C, and chloroquine on the frequency of radioninduced strand breaks in X-irradiated aqueous solutions of DNA was studied primarily by analytical ultracentrifugation using the sedimentation velocity method. The results show a potent radiosensitizing effect for daunomycin and chromomycin, a protective action for chloroquine and mitomycin, and a nonmodifying effect for anthramycin. Cisplatin forms a highly aggregated complex with DNA which prevents this kind of study

  15. DNA hybridization on membrane-modified carbon electrodes

    Kouřilová, Alena; Babkina, S. S.; Cahová, Kateřina; Havran, Luděk; Jelen, František; Paleček, Emil; Fojta, Miroslav

    2005-01-01

    Roč. 38, - (2005), s. 2493-2507 ISSN 0003-2719 R&D Projects: GA MPO(CZ) 1H-PK/42; GA AV ČR(CZ) IAA4004402; GA AV ČR(CZ) IBS5004355 Institutional research plan: CEZ:AV0Z50040507 Keywords : DNA hybridization * electrochemical DNA sensor * nitrocellulose membrane Subject RIV: BO - Biophysics Impact factor: 1.036, year: 2005

  16. The Inhibition Effect of Cell DNA Oxidative Damage and LDL Oxidation by Bovine Colostrums

    Chih-Wei Chen

    2016-10-01

    Full Text Available In the present study, we investigated the effect of bovine colostrums on inhibition of DNA oxidative damage and low density lipoprotein (LDL oxidation in vitro. Results showed that whey and skimmed milk exhibited not only higher inhibitory activities of oxidative damage of deoxyribose but also an inhibitory effect on the breakdown of supercoiled DNA into open circular DNA and linear DNA. The quantities of 8-OH-2′-dG formed under whey, caseins and skimmed milk treatment were 0.24, 0.24 and 1.24 μg/mL, respectively. The quantity of malondialdehyde formed through LDL oxidation induced by copprous ion was significantly decreased as colostrums protein solutions were added, in which whey and caseins led to a more significant decrease than skimmed milk. The formation of conjugated dienes could be inhibited by treatment with colostrums protein solutions. Whey exhibited the longest lag time of conjugated dienes formation among the colostrums proteins. The lag time of the whey was 2.33 times that of the control. From the results of foregoing, the bovine colostrums protein has potential value in the inhibition of DNA oxidation damage and LDL oxidation.

  17. High-affinity triplex targeting of double stranded DNA using chemically modified peptide nucleic acid oligomers

    Hansen, Mads E; Bentin, Thomas; Nielsen, Peter E

    2009-01-01

    While sequence-selective dsDNA targeting by triplex forming oligonucleotides has been studied extensively, only very little is known about the properties of PNA-dsDNA triplexes-mainly due to the competing invasion process. Here we show that when appropriately modified using pseudoisocytosine subs...

  18. [Application of DNA extraction kit, 'GM quicker' for detection of genetically modified soybeans].

    Sato, Noriko; Sugiura, Yoshitsugu; Tanaka, Toshitsugu

    2012-01-01

    Several DNA extraction methods have been officially introduced to detect genetically modified soybeans, but the choice of DNA extraction kits depend on the nature of the samples, such as grains or processed foods. To overcome this disadvantage, we examined whether the GM quicker kit is available for both grains and processed foods. We compared GM quicker with four approved DNA extraction kits in respect of DNA purity, copy numbers of lectin gene, and working time. We found that the DNA quality of GM quicker was superior to that of the other kits for grains, and the procedure was faster. However, in the case of processed foods, GM quicker was not superior to the other kits. We therefore investigated an unapproved GM quicker 3 kit, which is available for DNA extraction from processed foods, such as tofu and boiled soybeans. The GM quicker 3 kit provided good DNA quality from both grains and processed foods, so we made a minor modification of the GM quicker-based protocol that was suitable for processed foods, using GM quicker and its reagents. The modified method enhanced the performance of GM quicker with processed foods. We believe that GM quicker with the modified protocol is an excellent tool to obtain high-quality DNA from grains and processed foods for detection of genetically modified soybeans.

  19. Regulation of DNA double-strand break repair by ubiquitin and ubiquitin-like modifiers

    Schwertman, Petra; Bekker-Jensen, Simon; Mailand, Niels

    2016-01-01

    DNA double-strand breaks (DSBs) are highly cytotoxic DNA lesions. The swift recognition and faithful repair of such damage is crucial for the maintenance of genomic stability, as well as for cell and organismal fitness. Signalling by ubiquitin, SUMO and other ubiquitin-like modifiers (UBLs...

  20. Correspondence between radioactive and functional methods in the quality control of DNA restriction and modifying enzymes

    Trujillo, L E; Pupo, E; Miranda, F

    1996-01-01

    We evaluated the use of two radiolabeled lambda DNA/Hpa II substrates to detect 5'-->3', 3'-->5' single and double stranded DNA dependent exonuclease and phosphatase activities found as contaminants in restriction and modifying enzyme preparations. Looking for the meaning of the radioactive assay...

  1. Modified silver nanowire transparent electrodes with exceptional stability against oxidation

    Idier, J; Neri, W; Ly, I; Poulin, P; Backov, R; Labrugère, C

    2016-01-01

    We report an easy method to prepare thin, flexible and transparent electrodes that show enhanced inertness toward oxidation using modified silver nanowires (Ag NWs). Stabilization is achieved through the adsorption of triphenylphosphine (PPh 3 ) onto the Ag NW hybrid dispersions prior to their 2D organization as transparent electrodes on polyethylene terephtalate (PET) films. After 110 days in air (20 °C) under atmospheric conditions, the transmittance of the PET/Ag NW/PPh 3 based films is nearly unchanged, while the transmittance of the PET/Ag NW-based films decreases by about 5%. The sheet resistance increases for both materials as time elapses, but the rate of increase is more than four times slower for films stabilized by PPh 3 . The improved transmittance and conductivity results in a significantly enhanced stability for the figure of merit σ dc /σ op . This phenomenon is highlighted in highly oxidative nitric acid vapor. The tested stabilized films in such conditions exhibit a decrease to σ dc /σ op of only 38% after 75 min, whereas conventional materials exhibit a relative loss of 71%. In addition, by contrast to other classes of stabilizers, such as polymer or graphene-based encapsulants, PPh 3 does not alter the transparency or conductivity of the modified films. While the present films are made by membrane filtration, the stabilization method could be implemented directly in other liquid processes, including industrially scalable ones. (paper)

  2. A DNA biosensor based on the electrocatalytic oxidation of amine by a threading intercalator

    Gao Zhiqiang; Tansil, Natalia

    2009-01-01

    An electrochemical biosensor for the detection of DNA based a peptide nucleic acid (PNA) capture probe (CP) modified indium tin oxide electrode (ITO) is described in this report. After hybridization, a threading intercalator, N,N'-bis[(3-propyl)-imidazole]-1,4,5,8-naphthalene diimide (PIND) imidazole complexed with Ru(bpy) 2 Cl (PIND-Ru, bpy = 2,2'-bipyridine), was introduced to the biosensor. PIND-Ru selectively intercalated to double-stranded DNA (ds-DNA) and became immobilized on the biosensor surface. Voltammetric tests showed highly stable and reversible electrochemical oxidation/reduction processes and the peak currents can directly be utilized for DNA quantification. When the tests were conducted in an amine-containing medium, Tris-HCl buffer for example, a remarkable improvement in the voltammetric response and noticeable enhancements of voltammetric and amperometric sensitivities were observed due to the electrocatalytic activity of the [Ru(bpy) 2 Cl] redox moieties. Electrocatalytic current was observed when as little as 3.0 attomoles of DNA was present in the sample solution

  3. Radiation chemical and photochemical study of Z-DNA modified by 2-aminopurine and 8- bromodeoxyguanosine

    Kimura, T.; Kawai, K.; Majima, T.

    2003-01-01

    DNA is able to take a number of local conformations. (CG) n repeats have the highest potential to Z-DNA which has a left-handed zig-zag backbone and unusual syn-conformation purine base. Because of the polymorphic nature of dinucleotide repeats, it seems possible that Z-DNA forming sequences may provide a source of genetic variation if they occur in regions that are important for the regulation of gene activity. Here, we investigated structural properties of Z-DNA compared with those of B-DNA with respects to one-electron attachment reaction of 8-bromodeoxyguanosine (dBrG) and fluorescence properties of 2-aminopurine (Ap). To investigate one-electron attachment reaction of Z-DNA, we synthesized oligodeoxynucleotides modified by dBrG in which syn-conformation deoxyguanosine was stabilized by steric repulsion between 8-bromo group of dBrG and sugar moiety in Z-DNA. Debromination from the dBrG modified oligodeoxynucleotides occurred from the one-electron attachment during the gamma-ray irradiation. The structural dependence of B- and Z-DNA was observed in the one-electron attachment reaction. Interestingly, the higher conversion of dBrG were observed in the Z-DNA than in the B-DNA. Since the solvent accessibility to purine base in Z-DNA increases compared with that in B-DNA, it is suggested that the electron attachment is enhanced in Z-DNA than in B-DNA. Next we studied the fluorescence properties of Ap in left-handed Z-DNA and compared with those in B-DNA. Since photoexcited adenine analogue Ap can serve as a sensitive probe of DNA structural dynamics, we synthesized Ap- and dBrG-modified oligodeoxynucleotides. Higher intensity was observed in the steady-state fluorescence of Ap in Z-DNA than in B-DNA. A new peak at 275 nm was observed in the excitation spectrum measured at the Ap emission wavelength 370 nm in Z-DNA. This has been explained by the energy transfer from the excited nucleobases to Ap. It is found that Ap is a useful fluorescence probe of Z-DNA

  4. Electron transfer oxidation of DNA radicals by paranitroacetophenone

    Whillans, D W; Adams, G E [Mount Vernon Hospital, Northwood (UK)

    1975-12-01

    The reaction of a typical electron-affinic sensitizer, paranitroacetophenone (PNAP) with the model compounds thymine, thymidine, thymidylic acid, deoxyribose and single and double-stranded DNA has been investigated by pulse radiolysis. Radicals formed by one-electron reduction of the bases and of DNA reacted rapidly and efficiently with PNAP by electron transfer. A small yield of transfer (< 10 per cent) was also observed arising from oxidation of the radicals formed by the small proportion of OH which reacted at the sugar moieties in DNA. In contrast, electron transfer oxidation by PNAP of radicals formed by the addition of OH to the base moieties, e.g. thymine, was not an efficient process. Further, addition of the sensitizer to the thymine OH-adduct proceeded at a rate that was too low to measure the pulse radiolysis. We conclude that, since the major sites of OH reaction by DNA are the heterocyclic bases (> 80 per cent), oxidation of the resultant radicals is unlikely to be a major step in the mechanism of sensitization by this typical hypoxic-cell sensitizer.

  5. Synthesis and characterization of graphene oxide using modified Hummer's method

    Kaur, Manpreet; Kaur, Harsimran; Kukkar, Deepak

    2018-05-01

    In the present study, a simple approach has been followed for the synthesis of graphene oxide (GO) using modified Hummers method in which graphite powder was oxidized in the presence of concentrated H2SO4 and KMnO4. The amount of NaNO3 and KMnO4 was varied to produce sheet like structure. The varied concentrations of NaNO3 and KMnO4 resulted in yielding large amount of the product. Structural, morphological and physicochemical features of the product were studied using UV-Visible spectrophotometer, Fourier Transform infrared spectroscopy (FTIR), and crystal structure was determined using X-ray powder diffraction (XRD). UV-Vis spectra of GO was observed at a maximum absorption of 230 nm due to (π-π*) transition of atomic carbon-carbon bonds. FTIR spectra revealed the presence of oxygen containing functional groups which ensures the complete exfoliation of graphite into graphene oxide X-ray powder diffraction pattern of the product showed the diffraction peak at (2θ = 26.7°) with an interlayer spacing of 0.334 nm. All the above characterizations successfully confirmed the formation of GO.

  6. Oxidative damage of DNA in subjects occupationally exposed to lead.

    Pawlas, Natalia; Olewińska, Elżbieta; Markiewicz-Górka, Iwona; Kozłowska, Agnieszka; Januszewska, Lidia; Lundh, Thomas; Januszewska, Ewa; Pawlas, Krystyna

    2017-09-01

    Exposure to lead (Pb) in environmental and occupational settings continues to be a serious public health problem and may pose an elevated risk of genetic damage. The aim of this study was to assess the level of oxidative stress and DNA damage in subjects occupationally exposed to lead. We studied a population of 78 male workers exposed to lead in a lead and zinc smelter and battery recycling plant and 38 men from a control group. Blood lead levels were detected by graphite furnace atomic absorption spectrophotometry and plasma lead levels by inductively coupled plasma-mass spectrometry. The following assays were performed to assess the DNA damage and oxidative stress: comet assay, determination of 8-hydroxy-2'-deoxyguanosine (8-OHdG), lipid peroxidation and total antioxidant status (TAS). The mean concentration of lead in the blood of the exposed group was 392 ± 103 μg/L and was significantly higher than in the control group (30.3 ± 29.4 μg/L, p lead exposure [lead in blood, lead in plasma, zinc protoporphyrin (ZPP)] and urine concentration of 8-OHdG. The level of oxidative damage of DNA was positively correlated with the level of lipid peroxidation (TBARS) and negatively with total anti-oxidative status (TAS). Our study suggests that occupational exposure causes an increase in oxidative damage to DNA, even in subjects with relatively short length of service (average length of about 10 years). 8-OHdG concentration in the urine proved to be a sensitive and non-invasive marker of lead induced genotoxic damage.

  7. Endogenous melatonin and oxidatively damaged guanine in DNA

    Davanipour, Zoreh; Poulsen, Henrik E; Weimann, Allan

    2009-01-01

    overnight guanine DNA damage. 8-oxodG and 8-oxoGua were measured using a high-performance liquid chromatography-electrospray ionization tandem mass spectrometry assay. The mother, father, and oldest sampled daughter were used for these analyses. Comparisons between the mothers, fathers, and daughters were...... attack and increase the rate of repair of that damage. This paper reports the results of a study relating the level of overnight melatonin production to the overnight excretion of the two primary urinary metabolites of the repair of oxidatively damaged guanine in DNA. METHODS: Mother...

  8. Thickness, morphology, and optoelectronic characteristics of pristine and surfactant-modified DNA thin films

    Arasu, Velu; Reddy Dugasani, Sreekantha; Son, Junyoung; Gnapareddy, Bramaramba; Ha Park, Sung; Jeon, Sohee; Jeong, Jun-Ho

    2017-01-01

    Although the preparation of DNA thin films with well-defined thicknesses controlled by simple physical parameters is crucial for constructing efficient, stable, and reliable DNA-based optoelectronic devices and sensors, it has not been comprehensively studied yet. Here, we construct DNA and surfactant-modified DNA thin films by drop-casting and spin-coating techniques. The DNA thin films formed with different control parameters, such as drop-volume and spin-speed at given DNA concentrations, exhibit characteristic thickness, surface roughness, surface potential, and absorbance, which are measured by a field emission scanning electron microscope, a surface profilometer, an ellipsometer, an atomic force microscope, a Kelvin probe force microscope, and an UV–visible spectroscope. From the observations, we realized that thickness significantly affects the physical properties of DNA thin films. This comprehensive study of thickness-dependent characteristics of DNA and surfactant-modified DNA thin films provides insight into the choice of fabrication techniques in order for the DNA thin films to have desired physical characteristics in further applications, such as optoelectronic devices and sensors. (paper)

  9. Monoclonal antibodies to DNA modified with cis- or trans-diamminedichloroplatinum(II)

    Sundquist, W.I.; Lippard, S.J.; Stollar, B.D.

    1987-01-01

    Murine monoclonal antibodies that bind selectively to adducts formed on DNA by the antitumor drug cis-diamminedichloroplatinum(II), cis-DDP, or to the chemothrapeutically inactive trans isomer trans-DDP were elicited by immunization with calf thymus DNA modified with either cis- or trans-DDP at ratios of bound platinum per nucleotide, (D/N)/sub b/, of 0.06-0.08. The binding of two monoclonal antibodies to cis-DDP-modified DNA was competitively inhibited in an enzyme-linked immunosorbent assay (ELISA) by 4-6 nM concentrations of cis-DDP bound to DNA. Adducts formed by cis-DDP on other synthetic DNA polymers did not inhibit antibody binding to cis-DDP-DNA. The biologically active compounds [Pt(en)Cl 2 ], [Pt(dach)Cl 2 ], and [Pt(NH 3 ) 2 (cbdca)] (carboplatin) all formed antibody-detectable adducts on DNA, whereas the inactive platinum complexes trans-DDP and [Pt(dien)Cl]Cl (dien, diethylenetriamine) did not. The monoclonal antibodies therefore recognize a bifunctional Pt-DNA adduct with cis stereochemistry in which platinum is coordinated by two adjacent guanines or, to a lesser degree, by adjacent adenine and guanine. A monoclonal antibody raised against trans-DDP-DNA was competitively inhibited in an ELISA by 40 nM trans-DDP bound to DNA. This antibody crossreacted with unmodified, denatured DNA. The recognition of cis- or trans-DDP-modified DNAs by monoclonal antibodies thus parallels the known modes of DNA binding of these compounds and may correlate with their biological activities

  10. Personal exposure to ultrafine particles and oxidative DNA damage

    Vinzents, Peter S; Møller, Peter; Sørensen, Mette

    2005-01-01

    10), nitrous oxide, nitrogen dioxide, carbon monoxide, and/or number concentration of UFPs at urban background or busy street monitoring stations was not a significant predictor of DNA damage, although personal UFP exposure was correlated with urban background concentrations of CO and NO2...... the morning after exposure measurement. Cumulated outdoor and cumulated indoor exposures to UFPs each were independent significant predictors of the level of purine oxidation in DNA but not of strand breaks. Ambient air concentrations of particulate matter with an aerodynamic diameter of ..., particularly during bicycling in traffic. The results indicate that biologic effects of UFPs occur at modest exposure, such as that occurring in traffic, which supports the relationship of UFPs and the adverse health effects of air pollution....

  11. High Efficiency Acetylcholinesterase Immobilization on DNA Aptamer Modified Surfaces

    Orada Chumphukam

    2014-04-01

    Full Text Available We report here the in vitro selection of DNA aptamers for electric eel acetylcholinesterase (AChE. One selected aptamer sequence (R15/19 has a high affinity towards the enzyme (Kd = 157 ± 42 pM. Characterization of the aptamer showed its binding is not affected by low ionic strength (~20 mM, however significant reduction in affinity occurred at high ionic strength (~1.2 M. In addition, this aptamer does not inhibit the catalytic activity of AChE that we exploit through immobilization of the DNA on a streptavidin-coated surface. Subsequent immobilization of AChE by the aptamer results in a 4-fold higher catalytic activity when compared to adsorption directly on to plastic.

  12. Metal oxides modified NiO catalysts for oxidative dehydrogenation of ethane to ethylene

    Zhu, Haibo

    2014-06-01

    The sol-gel method was applied to the synthesis of Zr, Ti, Mo, W, and V modified NiO based catalysts for the ethane oxidative dehydrogenation reaction. The synthesized catalysts were characterized by XRD, N2 adsorption, SEM and TPR techniques. The results showed that the doping metals could be highly dispersed into NiO domains without the formation of large amount of other bulk metal oxide. The modified NiO materials have small particle size, larger surface area, and higher reduction temperature in contrast to pure NiO. The introduction of group IV, V and VI transition metals into NiO decreases the catalytic activity in ethane ODH. However, the ethylene selectivity is enhanced with the highest level for the Ni-W-O and Ni-Ti-O catalysts. As a result, these two catalysts show improved efficiency of ethylene production in the ethane ODH reaction. © 2014 Elsevier B.V. All rights reserved.

  13. Sex determination based on amelogenin DNA by modified electrode with gold nanoparticle.

    Mazloum-Ardakani, Mohammad; Rajabzadeh, Nooshin; Benvidi, Ali; Heidari, Mohammad Mehdi

    2013-12-15

    We have developed a simple and renewable electrochemical biosensor based on carbon paste electrode (CPE) for the detection of DNA synthesis and hybridization. CPE was modified with gold nanoparticles (AuNPs), which are helpful for immobilization of thiolated bioreceptors. AuNPs were characterized by scanning electron microscopy (SEM). Self-assembled monolayers (SAMs) of thiolated single-stranded DNA (SH-ssDNA) of the amelogenin gene was formed on CPE. The immobilization of the probe and its hybridization with the target DNA was optimized using different experimental conditions. The modified electrode was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The electrochemical response of ssDNA hybridization and DNA synthesis was measured using differential pulse voltammetry (DPV) with methylene blue (MB) as an electroactive indicator. The new biosensor can distinguish between complementary and non-complementary strands of amelogenin ssDNA. Genomic DNA was extracted from blood and was detected based on changes in the MB reduction signal. These results demonstrated that the new biosensor could be used for sex determination. The proposed biosensor in this study could be used for detection and discrimination of polymerase chain reaction (PCR) products of amelogenin DNA. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Bioorthogonal Metabolic DNA Labelling using Vinyl Thioether-Modified Thymidine and o-Quinolinone Quinone Methide.

    Gubu, Amu; Li, Long; Ning, Yan; Zhang, Xiaoyun; Lee, Seonghyun; Feng, Mengke; Li, Qiang; Lei, Xiaoguang; Jo, Kyubong; Tang, Xinjing

    2018-04-17

    Bioorthogonal metabolic DNA labeling with fluorochromes is a powerful strategy to visualize DNA molecules and their functions. Here, we report the development of a new DNA metabolic labeling strategy enabled by the catalyst-free bioorthogonal ligation using vinyl thioether modified thymidine and o-quinolinone quinone methide. With the newly designed vinyl thioether-modified thymidine (VTdT), we added labeling tags on cellular DNA, which could further be linked to fluorochromes in cells. Therefore, we successfully visualized the DNA localization within cells as well as single DNA molecules without other staining reagents. In addition, we further characterized this bioorthogonal DNA metabolic labeling using DNase I digestion, MS characterization of VTdT as well as VTdT-oQQF conjugate in cell nuclei or mitochondria. This technique provides a powerful strategy to study DNA in cells, which paves the way to achieve future spatiotemporal deciphering of DNA synthesis and functions. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. GSTP1 Loss results in accumulation of oxidative DNA base damage and promotes prostate cancer cell survival following exposure to protracted oxidative stress.

    Mian, Omar Y; Khattab, Mohamed H; Hedayati, Mohammad; Coulter, Jonathan; Abubaker-Sharif, Budri; Schwaninger, Julie M; Veeraswamy, Ravi K; Brooks, James D; Hopkins, Lisa; Shinohara, Debika Biswal; Cornblatt, Brian; Nelson, William G; Yegnasubramanian, Srinivasan; DeWeese, Theodore L

    2016-02-01

    Epigenetic silencing of glutathione S-transferase π (GSTP1) is a hallmark of transformation from normal prostatic epithelium to adenocarcinoma of the prostate. The functional significance of this loss is incompletely understood. The present study explores the effects of restored GSTP1 expression on glutathione levels, accumulation of oxidative DNA damage, and prostate cancer cell survival following oxidative stress induced by protracted, low dose rate ionizing radiation (LDR). GSTP1 protein expression was stably restored in LNCaP prostate cancer cells. The effect of GSTP1 restoration on protracted LDR-induced oxidative DNA damage was measured by GC-MS quantitation of modified bases. Reduced and oxidized glutathione levels were measured in control and GSTP1 expressing populations. Clonogenic survival studies of GSTP1- transfected LNCaP cells after exposure to protracted LDR were performed. Global gene expression profiling and pathway analysis were performed. GSTP1 expressing cells accumulated less oxidized DNA base damage and exhibited decreased survival compared to control LNCaP-Neo cells following oxidative injury induced by protracted LDR. Restoration of GSTP1 expression resulted in changes in modified glutathione levels that correlated with GSTP1 protein levels in response to protracted LDR-induced oxidative stress. Survival differences were not attributable to depletion of cellular glutathione stores. Gene expression profiling and pathway analysis following GSTP1 restoration suggests this protein plays a key role in regulating prostate cancer cell survival. The ubiquitous epigenetic silencing of GSTP1 in prostate cancer results in enhanced survival and accumulation of potentially promutagenic DNA adducts following exposure of cells to protracted oxidative injury suggesting a protective, anti-neoplastic function of GSTP1. The present work provides mechanistic backing to the tumor suppressor function of GSTP1 and its role in prostate carcinogenesis. © 2015

  16. Modified DNA extraction for rapid PCR detection of methicillin-resistant staphylococci

    Japoni, A.; Alborzi, A.; Rasouli, M.; Pourabbas, B.

    2004-01-01

    Nosocomial infection caused by methicillin-resistant staphylococci poses a serious problem in many countries. The aim of this study was to rapidly and reliably detect methicillin-resistant-staphylococci in order to suggest appropriate therapy. The presence or absence of the methicillin-resistance gene in 115 clinical isolates of staphylococcus aureus and 50 isolates of coagulase negative staphylococci was examined by normal PCR. DNA extraction for PCR performance was then modified by omission of achromopeptadiase and proteinase K digestion, phenol/chloroform extraction and ethanol precipitation. All isolates with Mic>8 μ g/ml showed positive PCR. No differences in PCR detection have been observed when normal and modified DNA extractions have been performed. Our modified DNA extraction can quickly detect methicillin-resistant staphylococci by PCR. The advantage of rapid DNA extraction extends to both reduction of time and cost of PCR performance. This modified DNA extraction is suitable for different PCR detection, when staphylococci are the subject of DNA analysis

  17. Measurement and meaning of oxidatively modified DNA lesions in urine

    Cooke, Marcus S; Olinski, Ryszard; Loft, Steffen

    2008-01-01

    and cell death have minimal, if any, influence upon urinary levels of 8-oxodG and 8-oxo-7,8-dihydroguanine, although this should be assessed on a lesion-by-lesion basis. Broadly speaking, there is consensus between chromatographic techniques; however, ELISA approaches continue to overestimate 8-oxod...

  18. Measurement of oxidative damage to DNA in nanomaterial exposed cells and animals

    Møller, Peter; Jensen, Ditte Marie; Christophersen, Daniel Vest

    2015-01-01

    -reactivity with other molecules in cells. This review provides an overview of efforts to reliably detect oxidatively damaged DNA and a critical assessment of the published studies on DNA damage levels. Animal studies with high baseline levels of oxidatively damaged DNA are more likely to show positive associations...... of oxidatively damaged DNA in lung tissue. Oral exposure to nanosized carbon black, TiO2 , carbon nanotubes and ZnO is associated with elevated levels of oxidatively damaged DNA in tissues. These observations are supported by cell culture studies showing concentration-dependent associations between ENM exposure...... and oxidatively damaged DNA measured by the comet assay. Cell culture studies show relatively high variation in the ability of ENMs to oxidatively damage DNA; hence, it is currently impossible to group ENMs according to their DNA damaging potential. Environ. Mol. Mutagen., 2014. © 2014 Wiley Periodicals, Inc....

  19. Electrochemical impedance-based DNA sensor using a modified single walled carbon nanotube electrode

    Weber, Jessica E. [Department of Mechanical Engineering, University of South Florida, Tampa, FL (United States); Nanomaterials and Nanomanufacturing Research Center, University of South Florida, Tampa, FL (United States); Pillai, Shreekumar [Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL (United States); Ram, Manoj Kumar, E-mail: mkram@usf.edu [Department of Mechanical Engineering, University of South Florida, Tampa, FL (United States); Nanomaterials and Nanomanufacturing Research Center, University of South Florida, Tampa, FL (United States); Kumar, Ashok [Department of Mechanical Engineering, University of South Florida, Tampa, FL (United States); Nanomaterials and Nanomanufacturing Research Center, University of South Florida, Tampa, FL (United States); Singh, Shree R. [Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL (United States)

    2011-07-20

    Carbon nanotubes have become promising functional materials for the development of advanced electrochemical biosensors with novel features which could promote electron-transfer with various redox active biomolecules. This paper presents the detection of Salmonella enterica serovar Typhimurium using chemically modified single walled carbon nanotubes (SWNTs) with single stranded DNA (ssDNA) on a polished glassy carbon electrode. Hybridization with the corresponding complementary ssDNA has shown a shift in the impedance studies due to a higher charge transfer in ssDNA. The developed biosensor has revealed an excellent specificity for the appropriate targeted DNA strand. The methodologies to prepare and functionalize the electrode could be adopted in the development of DNA hybridization biosensor.

  20. Iron and manganese oxides modified maize straw to remove tylosin from aqueous solutions.

    Yin, Yongyuan; Guo, Xuetao; Peng, Dan

    2018-08-01

    Maize straw modified by iron and manganese oxides was synthesized via a simple and environmentally friendly method. Three maize straw materials, the original maize straw, maize straw modified by manganese oxides and maize straw modified by iron and manganese oxides, were detected by SEM, BET, XPS, XRD and FTIR. The results showed that maize straw was successfully modified and maize straw modified by iron and manganese oxides has a larger surface area than MS. According to the experimental data, the sorption trend could conform to the pseudo-second-order kinetic model well, and the sorption ability of tylosin on sorbents followed the order of original maize straw oxides iron and manganese oxides. The study indicated that manganese oxides and iron-manganese oxides could significantly enhance the sorption capacity of original maize straw. The sorption isotherm data of tylosin on original maize straw fit a linear model well, while Freundlich models were more suitable for maize straw modified by manganese oxides and maize straw modified by iron and manganese oxides. The pH, ionic strength and temperature can affect the sorption process. The sorption mechanisms of tylosin on iron and manganese oxides modified maize straw were attribute to the surface complexes, electrostatic interactions, H bonding and hydrophobic interactions. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Endogenous melatonin and oxidatively damaged guanine in DNA

    Poulsen Henrik E

    2009-10-01

    Full Text Available Abstract Background A significant body of literature indicates that melatonin, a hormone primarily produced nocturnally by the pineal gland, is an important scavenger of hydroxyl radicals and other reactive oxygen species. Melatonin may also lower the rate of DNA base damage resulting from hydroxyl radical attack and increase the rate of repair of that damage. This paper reports the results of a study relating the level of overnight melatonin production to the overnight excretion of the two primary urinary metabolites of the repair of oxidatively damaged guanine in DNA. Methods Mother-father-daughter(s families (n = 55 were recruited and provided complete overnight urine samples. Total overnight creatinine-adjusted 6-sulphatoxymelatonin (aMT6s/Cr has been shown to be highly correlated with total overnight melatonin production. Urinary 8-oxo-7,8-dihydro-guanine (8-oxoGua results from the repair of DNA or RNA guanine via the nucleobase excision repair pathway, while urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG may possibly result from the repair of DNA guanine via the nucleotide excision repair pathway. Total overnight urinary levels of 8-oxodG and 8-oxoGua are therefore a measure of total overnight guanine DNA damage. 8-oxodG and 8-oxoGua were measured using a high-performance liquid chromatography-electrospray ionization tandem mass spectrometry assay. The mother, father, and oldest sampled daughter were used for these analyses. Comparisons between the mothers, fathers, and daughters were calculated for aMT6s/Cr, 8-oxodG, and 8-oxoGua. Regression analyses of 8-oxodG and 8-oxoGua on aMT6s/Cr were conducted for mothers, fathers, and daughters separately, adjusting for age and BMI (or weight. Results Among the mothers, age range 42-80, lower melatonin production (as measured by aMT6s/CR was associated with significantly higher levels of 8-oxodG (p Conclusion Low levels of endogenous melatonin production among older individuals may lead to

  2. Enzymatic Incorporation of Modified Purine Nucleotides in DNA.

    Abu El Asrar, Rania; Margamuljana, Lia; Abramov, Mikhail; Bande, Omprakash; Agnello, Stefano; Jang, Miyeon; Herdewijn, Piet

    2017-12-14

    A series of nucleotide analogues, with a hypoxanthine base moiety (8-aminohypoxanthine, 1-methyl-8-aminohypoxanthine, and 8-oxohypoxanthine), together with 5-methylisocytosine were tested as potential pairing partners of N 8 -glycosylated nucleotides with an 8-azaguanine or 8-aza-9-deazaguanine base moiety by using DNA polymerases (incorporation studies). The best results were obtained with the 5-methylisocytosine nucleotide followed by the 1-methyl-8-aminohypoxanthine nucleotide. The experiments demonstrated that small differences in the structure (8-azaguanine versus 8-aza-9-deazaguanine) might lead to significant differences in recognition efficiency and selectivity, base pairing by Hoogsteen recognition at the polymerase level is possible, 8-aza-9-deazaguanine represents a self-complementary base pair, and a correlation exists between in vitro incorporation studies and in vivo recognition by natural bases in Escherichia coli, but this recognition is not absolute (exceptions were observed). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Synthesis of modified oligonucleotides for repair and replication studies of single and double radio-induced DNA lesions

    Muller, E.

    2002-01-01

    Several oxidative processes induce the formation of DNA lesions. In order to evaluate the biological and structural significance of such damage, several DNA lesions were inserted into synthetic oligonucleotides at defined sites. The research work aimed at describing the preparation of oligonucleotides t hat contained DNA damage and the evaluation of the biological properties of the lesions. A first part described the incorporation of radiation-induced lesions, namely (5'S,6S)-5',6-cyclo-5,6-dihydro-2'-deoxyuridine and (5'S,5S,6S)-5',6-cyclo-5-hydroxy-5,6-dihydro-2'-desoxyuridine into oligonucleotides. The modified DNA fragments were characterised by several spectroscopic and biochemical analyses including ESI MS, MALDI-TOF MS, CLHP and enzymatic digestions. During in vitro DNA synthesis by Taq DNA polymerase and Klenow exo fragment, the pyrimidine cyclo-nucleosides were found to block the progression of the enzymes. Then, repair studies by ADN N glycosylases, operating in the base excision repair pathway, have shown that the anhydro-nucleoside lesions were not recognised nor excised by Fpg, endo III, endo VIII, yNtg1 yNtg2 and yOgg1. Interestingly, the Latococcus lactis Fpg protein recognises (formation of a non covalent complex) but do not excise the damage. The incorporation into oligonucleotides of the (5R*) and (5S*) diastereoisomers of 1-[2-deoxy-β-D-erythro-pentofuranosyl]-5-hydroxy-hydantoin, generated by several oxidative processes was then described. In vitro DNA replication assays using modified oligonucleotides matrix showed a lethal potential of the latter base damage. Repair studies by ADN N-glycosylases showed that the damage was substrate for Fpg, endo III, endo VIII, Ntg1, Ntg2 and Fpg-L1. The rates of excision as inferred from the determination of the Michaelis kinetics constants were found to be affected by the presence of the damage. MALDI-TOF MS was used in order to gain insights into mechanistic aspects of oligonucleotides cleavage by the

  4. Coordinating repair of oxidative DNA damage with transcription and replication

    Cooper, P.K.

    2003-01-01

    Transcription-coupled repair (TCR) preferentially removes DNA lesions from template strands of active genes. Defects in TCR, which acts both on lesions removed by nucleotide excision repair (NER) and on oxidative lesions removed by base excision repair (BER), underlie the fatal developmental disorder Cockayne syndrome. Although its detailed mechanism remains unknown, TCR involves recognition of a stalled RNA polymerase (RNAP), removal or remodeling of RNAP to allow access to the lesion, and recruitment of repair enzymes. At a minimum, these early steps require a non-enzymatic function of the multifunctional repair protein XPG, the CSB protein with ATP-dependent chromatin remodeling activity, and the TFIIH complex (including the XPB and XPD helicases) that is also required for basal transcription initiation and NER. XPG exists in the cell in a complex with TFIIH, and in vitro evidence has suggested that it interacts with CSB. To address the mechanism of TCR, we are characterizing protein-DNA and protein-protein interactions of XPG. We show that XPG preferentially binds to double-stranded DNA containing bubbles resembling in size the unpaired regions associated with transcription. Two distinct domains of XPG are required for the observed strong binding specificity and stability. XPG both interacts directly with CSB and synergistically binds with it to bubble DNA, and it strongly stimulates the bubble DNA-dependent ATPase activity of CSB. Significantly for TCR, XPG also interacts directly with RNAP II, binds both the protein and nucleic acid components (the R-loop) of a stalled RNA polymerase, and forms a ternary complex with CSB and the stalled RNAP. These results are consistent with the model that XPG and CSB jointly interact with the DNA/chromatin structure in the vicinity of the stalled transcriptional apparatus and with the transcriptional machinery itself to remodel the chromatin and either move or remodel the blocked RNA polymerase to expose the lesion

  5. Immunological detection of modified DNA bases in irradiated food

    Williams, J.H.H.; Tyreman, A.L.; Deeble, D.J.; Jones, M.; Smith, C.J.; Christiansen, J.F.; Beaumont, P.C.

    1996-01-01

    Ionising radiation is fatal to all known life forms given sufficient exposure in terms of dose and duration. This property has been used beneficially to sterilise a range of materials, particularly medical products where the removal of all contaminating organisms is deemed essential. Irradiation has long been used to sterilise food for consumption by certain categories of patients. The method is attractive because all potentially contaminating organisms can be removed by one simple treatment. Irradiation also slows down or stops certain processes such as sprouting. There are, however, disadvantages to irradiating food. It is not only DNA that is affected as alterations in lipid and protein components of the food may lead to a loss of quality. Although irradiation will kill bacteria it will probably not affect any toxin produced by those bacteria prior to treatment. Irradiation achieves its effects by damaging molecules, particularly nucleic acids. Consequently, if any of the damage to nucleic acids could be shown to by by a process unique to irradiation, and the products of this unique process could be measured, then there is the basis for a detection system. Furthermore, if the damage could be shown to be proportional to the dose of radiation received then the dose could also be quantified. Legislation, therefore, requires that assays be developed for use in different countries, those which totally ban irradiated food, those which require irradiated food to be labelled and those which have selective laws relating to specific foods and specific levels of irradiation. (author)

  6. DNA biosensor for detection of Salmonella typhi from blood sample of typhoid fever patient using gold electrode modified by self-assembled monolayers of thiols

    Suryapratiwi, Windha Novita; Paat, Vlagia Indira; Gaffar, Shabarni; Hartati, Yeni Wahyuni

    2017-05-01

    Electrochemical biosensors are currently being developed in order to handle various clinical problems in diagnosing infectious diseases caused by pathogenic bacteria, or viruses. On this research, voltammetric DNA biosensor using gold electrode modified by thiols with self-assembled monolayers had been developed to detect a certain sequence of Salmonella typhi DNA from blood sample of typhoid fever patient. Thiol groups of cysteamines (Cys) and aldehyde groups from glutaraldehydes (Glu) were used as a link to increase the performance of gold electrode in detecting guanine oxidation signal of hybridized S. typhi DNA and ssDNA probe. Standard calibration method was used to determine analytical parameters from the measurements. The result shown that, the detection of S. typhi DNA from blood sample of typhoid fever patient can be carried out by voltammetry using gold electrode modified by self-assembled monolayers of thiols. A characteristic oxidation potential of guanine using Au/Cys/Gluwas obtained at +0.17 until +0.20 V. Limit of detection and limit of quantification from this measurements were 1.91μg mL-1 and 6.35 μg mL-1. The concentration of complement DNA from sample was 6.96 μg mL-1.

  7. The emulsifying and tribological properties of modified graphene oxide in oil-in-water emulsion

    Wu, Yinglei; Zeng, Xiangqiong; Ren, Tianhui; de Vries, Erik G.; van der Heide, Emile

    2017-01-01

    Graphene oxide (GO) was asymmetric chemically modified with myristyltrimethylammonium bromide (TTAB) to get modified graphene oxide (MGO). This MGO was used as an emulsifier and additive in oil-in-water emulsion. The emulsifying tests showed MGO greatly improved the stability of base emulsion and

  8. Systemic oxidatively generated DNA/RNA damage in clinical depression

    Jorgensen, Anders; Krogh, Jesper; Miskowiak, Kamilla

    2013-01-01

    oxidatively generated DNA and RNA damage, 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo), respectively, were determined in healthy controls (N=28), moderately depressed, non-medicated patients (N=26) and severely depressed patients eligible for electroconvulsive therapy...... for trend=0.004). The 8-oxoGuo excretion was further increased after clinically effective ECT compared with pre-ECT values (P=0.006). There were no differences in 8-oxodG excretion between the groups or pre- vs. post-ECT. LIMITATIONS: Small sample size and the inclusion of both unipolar and bipolar patients...

  9. Oxidatively damaged DNA in animals exposed to particles

    Møller, Peter; Danielsen, Pernille Høgh; Jantzen, Kim

    2013-01-01

    on optimal methods. The majority of studies have used single intracavitary administration or inhalation with dose rates exceeding the pulmonary overload threshold, resulting in cytotoxicity and inflammation. It is unclear whether this is relevant for the much lower human exposure levels. Still...... not be equivocally determined. Roles of cytotoxicity or inflammation for oxidatively induced DNA damage could not be documented or refuted. Studies on exposure to particles in the gastrointestinal tract showed consistently increased levels of 8-oxo-7,8-dihydroguanine in the liver. Collectively, there is evidence...

  10. The basic chemistry of exercise-induced DNA oxidation: oxidative damage, redox signalling and their interplay

    James Nathan Cobley

    2015-06-01

    Full Text Available Acute exercise increases reactive oxygen and nitrogen species generation. This phenomenon is associated with two major outcomes: (1 redox signalling and (2 macromolecule damage. Mechanistic knowledge of how exercise-induced redox signalling and macromolecule damage are interlinked is limited. This review focuses on the interplay between exercise-induced redox signalling and DNA damage, using hydroxyl radical (·OH and hydrogen peroxide (H2O2 as exemplars. It is postulated that the biological fate of H2O2 links the two processes and thus represents a bifurcation point between redox signalling and damage. Indeed, H2O2 can participate in two electron signalling reactions but its diffusion and chemical properties permit DNA oxidation following reaction with transition metals and ·OH generation. It is also considered that the sensing of DNA oxidation by repair proteins constitutes a non-canonical redox signalling mechanism. Further layers of interaction are provided by the redox regulation of DNA repair proteins and their capacity to modulate intracellular H2O2 levels. Overall, exercise-induced redox signalling and DNA damage may be interlinked to a greater extent than was previously thought but this requires further investigation.

  11. Unusual hydrogen bonding patterns in AF [aminofluorene] and AAF [acetylaminofluorene] modified DNA

    Broyde, S.; Hingerty, B.E.; Shapiro, R.; Norman, D.; Oak Ridge National Lab., TN; New York Univ., NY; Columbia Univ., New York, NY

    1989-01-01

    New structures are presented for AF and AAF modified DNAs that place the carcinogen in the minor groove of a B-DNA helix. These structures employ non-Watson-Crick base pairing schemes with syn guanine at the modification site. 32 refs., 9 figs

  12. Cleavage and protection of locked nucleic acid-modified DNA by restriction endonucleases

    Crouzier, Lucile; Dubois, Camille; Wengel, Jesper

    2012-01-01

    Locked nucleic acid (LNA) is one of the most prominent nucleic acid analogues reported so far. We herein for the first time report cleavage by restriction endonuclease of LNA-modified DNA oligonucleotides. The experiments revealed that RsaI is an efficient enzyme capable of recognizing and cleaving...

  13. Oxidative DNA damage and oxidative stress in lead-exposed workers.

    Dobrakowski, M; Pawlas, N; Kasperczyk, A; Kozłowska, A; Olewińska, E; Machoń-Grecka, A; Kasperczyk, S

    2017-07-01

    There are many discrepancies among the results of studies on the genotoxicity of lead. The aim of the study was to explore lead-induced DNA damage, including oxidative damage, in relation to oxidative stress intensity parameters and the antioxidant defense system in human leukocytes. The study population consisted of 100 male workers exposed to lead. According to the blood lead (PbB) levels, they were divided into the following three subgroups: a group with PbB of 20-35 μg/dL (low exposure to lead (LE) group), a group with a PbB of 35-50 µg/dL (medium exposure to lead (ME) group), and a group with a PbB of >50 μg/dL (high exposure to lead (HE) group). The control group consisted of 42 healthy males environmentally exposed to lead (PbB lead exposure induces DNA damage, including oxidative damage, in human leukocytes. The increase in DNA damage was accompanied by an elevated intensity of oxidative stress.

  14. Singlet Oxygen-Mediated Oxidation during UVA Radiation Alters the Dynamic of Genomic DNA Replication.

    Dany Graindorge

    Full Text Available UVA radiation (320-400 nm is a major environmental agent that can exert its deleterious action on living organisms through absorption of the UVA photons by endogenous or exogenous photosensitizers. This leads to the production of reactive oxygen species (ROS, such as singlet oxygen (1O2 and hydrogen peroxide (H2O2, which in turn can modify reversibly or irreversibly biomolecules, such as lipids, proteins and nucleic acids. We have previously reported that UVA-induced ROS strongly inhibit DNA replication in a dose-dependent manner, but independently of the cell cycle checkpoints activation. Here, we report that the production of 1O2 by UVA radiation leads to a transient inhibition of replication fork velocity, a transient decrease in the dNTP pool, a quickly reversible GSH-dependent oxidation of the RRM1 subunit of ribonucleotide reductase and sustained inhibition of origin firing. The time of recovery post irradiation for each of these events can last from few minutes (reduction of oxidized RRM1 to several hours (replication fork velocity and origin firing. The quenching of 1O2 by sodium azide prevents the delay of DNA replication, the decrease in the dNTP pool and the oxidation of RRM1, while inhibition of Chk1 does not prevent the inhibition of origin firing. Although the molecular mechanism remains elusive, our data demonstrate that the dynamic of replication is altered by UVA photosensitization of vitamins via the production of singlet oxygen.

  15. Singlet Oxygen-Mediated Oxidation during UVA Radiation Alters the Dynamic of Genomic DNA Replication

    Graindorge, Dany; Martineau, Sylvain; Machon, Christelle; Arnoux, Philippe; Guitton, Jérôme; Francesconi, Stefania; Frochot, Céline; Sage, Evelyne; Girard, Pierre-Marie

    2015-01-01

    UVA radiation (320–400 nm) is a major environmental agent that can exert its deleterious action on living organisms through absorption of the UVA photons by endogenous or exogenous photosensitizers. This leads to the production of reactive oxygen species (ROS), such as singlet oxygen (1O2) and hydrogen peroxide (H2O2), which in turn can modify reversibly or irreversibly biomolecules, such as lipids, proteins and nucleic acids. We have previously reported that UVA-induced ROS strongly inhibit DNA replication in a dose-dependent manner, but independently of the cell cycle checkpoints activation. Here, we report that the production of 1O2 by UVA radiation leads to a transient inhibition of replication fork velocity, a transient decrease in the dNTP pool, a quickly reversible GSH-dependent oxidation of the RRM1 subunit of ribonucleotide reductase and sustained inhibition of origin firing. The time of recovery post irradiation for each of these events can last from few minutes (reduction of oxidized RRM1) to several hours (replication fork velocity and origin firing). The quenching of 1O2 by sodium azide prevents the delay of DNA replication, the decrease in the dNTP pool and the oxidation of RRM1, while inhibition of Chk1 does not prevent the inhibition of origin firing. Although the molecular mechanism remains elusive, our data demonstrate that the dynamic of replication is altered by UVA photosensitization of vitamins via the production of singlet oxygen. PMID:26485711

  16. Hydroxytyrosol Protects against Oxidative DNA Damage in Human Breast Cells

    José J. Gaforio

    2011-10-01

    Full Text Available Over recent years, several studies have related olive oil ingestion to a low incidence of several diseases, including breast cancer. Hydroxytyrosol and tyrosol are two of the major phenols present in virgin olive oils. Despite the fact that they have been linked to cancer prevention, there is no evidence that clarifies their effect in human breast tumor and non-tumor cells. In the present work, we present hydroxytyrosol and tyrosol’s effects in human breast cell lines. Our results show that hydroxytyrosol acts as a more efficient free radical scavenger than tyrosol, but both fail to affect cell proliferation rates, cell cycle profile or cell apoptosis in human mammary epithelial cells (MCF10A or breast cancer cells (MDA-MB-231 and MCF7. We found that hydroxytyrosol decreases the intracellular reactive oxygen species (ROS level in MCF10A cells but not in MCF7 or MDA-MB-231 cells while very high amounts of tyrosol is needed to decrease the ROS level in MCF10A cells. Interestingly, hydroxytyrosol prevents oxidative DNA damage in the three breast cell lines. Therefore, our data suggest that simple phenol hydroxytyrosol could contribute to a lower incidence of breast cancer in populations that consume virgin olive oil due to its antioxidant activity and its protection against oxidative DNA damage in mammary cells.

  17. Evaluation of plasmid and genomic DNA calibrants used for the quantification of genetically modified organisms.

    Caprioara-Buda, M; Meyer, W; Jeynov, B; Corbisier, P; Trapmann, S; Emons, H

    2012-07-01

    The reliable quantification of genetically modified organisms (GMOs) by real-time PCR requires, besides thoroughly validated quantitative detection methods, sustainable calibration systems. The latter establishes the anchor points for the measured value and the measurement unit, respectively. In this paper, the suitability of two types of DNA calibrants, i.e. plasmid DNA and genomic DNA extracted from plant leaves, for the certification of the GMO content in reference materials as copy number ratio between two targeted DNA sequences was investigated. The PCR efficiencies and coefficients of determination of the calibration curves as well as the measured copy number ratios for three powder certified reference materials (CRMs), namely ERM-BF415e (NK603 maize), ERM-BF425c (356043 soya), and ERM-BF427c (98140 maize), originally certified for their mass fraction of GMO, were compared for both types of calibrants. In all three systems investigated, the PCR efficiencies of plasmid DNA were slightly closer to the PCR efficiencies observed for the genomic DNA extracted from seed powders rather than those of the genomic DNA extracted from leaves. Although the mean DNA copy number ratios for each CRM overlapped within their uncertainties, the DNA copy number ratios were significantly different using the two types of calibrants. Based on these observations, both plasmid and leaf genomic DNA calibrants would be technically suitable as anchor points for the calibration of the real-time PCR methods applied in this study. However, the most suitable approach to establish a sustainable traceability chain is to fix a reference system based on plasmid DNA.

  18. Voltammetry of osmium-modified DNA at a mercury film electrode application in detecting DNA hybridization

    Kostečka, Pavel; Havran, Luděk; Pivoňková, Hana; Fojta, Miroslav

    2004-01-01

    Roč. 63, 1-2 (2004), s. 245-248 ISSN 1567-5394 R&D Projects: GA AV ČR IAA4004108; GA AV ČR KJB4004302 Institutional research plan: CEZ:AV0Z5004920 Keywords : osmium * DNA hybridization * mercury film electrode Subject RIV: BO - Biophysics Impact factor: 2.261, year: 2004

  19. Fisetin Protects DNA Against Oxidative Damage and Its Possible Mechanism.

    Wang, Tingting; Lin, Huajuan; Tu, Qian; Liu, Jingjing; Li, Xican

    2016-06-01

    The paper tries to assess the protective effect of fisetin against •OH-induced DNA damage, then to investigate the possible mechanism. The protective effect was evaluated based on the content of malondialdehyde (MDA). The possible mechanism was analyzed using various antioxidant methods in vitro, including •OH scavenging (deoxyribose degradation), •O2 (-) scavenging (pyrogallol autoxidation), DPPH• scavenging, ABTS•(+) scavenging, and Cu(2+)-reducing power assays. Fisetin increased dose-dependently its protective percentages against •OH-induced DNA damage (IC50 value =1535.00±29.60 µM). It also increased its radical-scavenging percentages in a dose-dependent manner in various antioxidants assays. Its IC50 values in •OH scavenging, •O2(-) scavenging, DPPH• scavenging, ABTS•(+) scavenging, and Cu(2+)-reducing power assays, were 47.41±4.50 µM, 34.05±0.87 µM, 9.69±0.53 µM, 2.43±0.14 µM, and 1.49±0.16 µM, respectively. Fisetin can effectively protect DNA against •OH-induced oxidative damage possibly via reactive oxygen species (ROS) scavenging approach, which is assumed to be hydrogen atom (H•) and/or single electron (e) donation (HAT/SET) pathways. In the HAT pathway, the 3',4'-dihydroxyl moiety in B ring of fisetin is thought to play an important role, because it can be ultimately oxidized to a stable ortho-benzoquinone form.

  20. The impact of arginine-modified chitosan-DNA nanoparticles on the function of macrophages

    Liu Lanxia; Bai Yuanyuan; Song Chunni; Zhu Dunwan; Song Liping; Zhang Hailing; Dong Xia; Leng Xigang, E-mail: lengxg@bme.org.c [Tianjin Key Laboratory of Biomedical Materials, Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Laboratory of Bioengineering (China)

    2010-06-15

    It has been demonstrated that incorporation of arginine moieties into chitosan significantly elevates the transgenic efficacy of the chitosan. However, little is known about the impact of arginine-modified chitosan on the function of macrophages, which play a vitally important role in the inflammatory response of the body to foreign substances, especially particulate substances. This study was designed to investigate the impact of arginine-modified chitosan/DNA nanoparticles on the function of the murine macrophage through observation of phagocytic activity and production of pro-inflammatory cytokines (IL-1{beta}, IL-6, IL-10, IL-12, and TNF-{alpha}). Results showed that both chitosan/DNA nanoparticles and arginine-modified chitosan/DNA nanoparticles, containing 20 {mu}g/mL DNA, were internalized by almost all the macrophages in contact. This led to no significant changes, compared to the non-exposure group, in production of cytokines and phagocytic activity of the macrophages 24 h post co-incubation, whereas exposure to LPS induced obviously elevated cytokine production and phagocytic activity, suggesting that incorporation of arginine moieties into chitosan does not have a negative impact on the function of the macrophages.

  1. DNA-repair measurements by use of the modified comet assay

    Godschalk, Roger W L; Ersson, Clara; Riso, Patrizia

    2013-01-01

    The measurement of DNA-repair activity by extracts from cells or tissues by means of the single-cell gel electrophoresis (comet) assay has a high potential to become widely used in biomonitoring studies. We assessed the inter-laboratory variation in reported values of DNA-repair activity...... on substrate cells that had been incubated with Ro19-8022 plus light to generate oxidatively damaged DNA. Eight laboratories assessed the DNA-repair activity of three cell lines (i.e. one epithelial and two fibroblast cell lines), starting with cell pellets or with cell extracts provided by the coordinating...... laboratory. There was a large inter-laboratory variation, as evidenced by the range in the mean level of repair incisions between the laboratory with the lowest (0.002incisions/10(6)bp) and highest (0.988incisions/10(6)bp) incision activity. Nevertheless, six out of eight laboratories reported the same cell...

  2. Detection of DNA damage by using hairpin molecular beacon probes and graphene oxide.

    Zhou, Jie; Lu, Qian; Tong, Ying; Wei, Wei; Liu, Songqin

    2012-09-15

    A hairpin molecular beacon tagged with carboxyfluorescein in combination with graphene oxide as a quencher reagent was used to detect the DNA damage by chemical reagents. The fluorescence of molecular beacon was quenched sharply by graphene oxide; while in the presence of its complementary DNA the quenching efficiency decreased because their hybridization prevented the strong adsorbability of molecular beacon on graphene oxide. If the complementary DNA was damaged by a chemical reagent and could not form intact duplex structure with molecular beacon, more molecular beacon would adsorb on graphene oxide increasing the quenching efficiency. Thus, damaged DNA could be detected based on different quenching efficiencies afforded by damaged and intact complementary DNA. The damage effects of chlorpyrifos-methyl and three metabolites of styrene such as mandelieaeids, phenylglyoxylieaeids and epoxystyrene on DNA were studied as models. The method for detection of DNA damage was reliable, rapid and simple compared to the biological methods. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. A simple approach for producing highly efficient DNA carriers with reduced toxicity based on modified polyallylamine

    Oskuee, Reza Kazemi [Neurogenic Inflammation Research Center, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of); Department of Medical Biotechnology, School of Medicine, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of); Dosti, Fatemeh [School of Pharmacy, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of); Gholami, Leila [Targeted Drug Delivery Research Center, School of Medicine, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of); Malaekeh-Nikouei, Bizhan, E-mail: malaekehb@mums.ac.ir [Nanotechnology Research Center, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad (Iran, Islamic Republic of)

    2015-04-01

    Nowadays gene delivery is a topic in many research studies. Non-viral vectors have many advantages over viral vectors in terms of safety, immunogenicity and gene carrying capacity but they suffer from low transfection efficiency and high toxicity. In this study, polyallylamine (PAA), the cationic polymer, has been modified with hydrophobic branches to increase the transfection efficiency of the polymer. Polyallylamine with molecular weights of 15 and 65 kDa was selected and grafted with butyl, hexyl and decyl acrylate at percentages of 10, 30 and 50. The ability of the modified polymer to condense DNA was examined by ethidium bromide test. The complex of modified polymer and DNA (polyplex) was characterized for size, zeta potential, transfection efficiency and cytotoxicity in Neuro2A cell lines. The results of ethidium bromide test showed that grafting of PAA decreased its ability for DNA condensation but vectors could still condense DNA at moderate and high carrier to DNA ratios. Most of polyplexes had particle size between 150 and 250 nm. The prepared vectors mainly showed positive zeta potential but carriers composed of PAA with high percentage of grafting had negative zeta potential. The best transfection activity was observed in vectors with hexyl acrylate chain. Grafting of polymer reduced its cytotoxicity especially at percentages of 30 and 50. The vectors based of PAA 15 kDa had better transfection efficiency than the vectors made of PAA 65 kDa. In conclusion, results of the present study indicated that grafting PAA 15 kDa with high percentages of hexyl acrylate can help to prepare vectors with better transfection efficiency and less cytotoxicity. - Highlights: • The modified polyallylamine was synthesized as a gene carrier. • Modification of polyallylamine (15 kDa) with high percentages of hexyl acrylate improved transfection activity remarkably. • Grafting of polymer with acrylate derivatives reduced polymer cytotoxicity especially at percentages of

  4. Emulsifying Property and Antioxidative Activity of Cuttlefish Skin Gelatin Modified with Oxidized Linoleic Acid and Oxidized Tannic Acid

    Aewsiri, T.; Benjakul, S.; Visessanguan, W.; Wierenga, P.A.; Gruppen, H.

    2013-01-01

    Cuttlefish skin gelatins modified with oxidized linoleic acid (OLA) and oxidized tannic acid (OTA) were characterized and determined for emulsifying properties and antioxidative activity. Modification of gelatin with 5% OTA increased the total phenolic content and 1,1-diphenyl-2-picrylhydrazyl,

  5. Synthesis of base-modified 2'-deoxyribonucleoside triphosphates and their use in enzymatic synthesis of modified DNA for applications in bioanalysis and chemical biology.

    Hocek, Michal

    2014-11-07

    The synthesis of 2'-deoxyribonucleoside triphosphates (dNTPs) either by classical triphosphorylation of nucleosides or by aqueous cross-coupling reactions of halogenated dNTPs is discussed. Different enzymatic methods for synthesis of modified oligonucleotides and DNA by polymerase incorporation of modified nucleotides are summarized, and the applications in redox or fluorescent labeling, as well as in bioconjugations and modulation of interactions of DNA with proteins, are outlined.

  6. Detection of Aeromonas hydrophila DNA oligonucleotide sequence using a biosensor design based on Ceria nanoparticles decorated reduced graphene oxide and Fast Fourier transform square wave voltammetry

    Jafari, Safiye [Center of Excellence in Electrochemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Faridbod, Farnoush, E-mail: faridbodf@khayam.ut.ac.ir [Center of Excellence in Electrochemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Biosensor Research Center, Endocrinology & Metabolism Molecular and Cellular Research Institute, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Norouzi, Parviz [Center of Excellence in Electrochemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Biosensor Research Center, Endocrinology & Metabolism Molecular and Cellular Research Institute, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Dezfuli, Amin Shiralizadeh [Center of Excellence in Electrochemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Ajloo, Davood [School of Chemistry, Damghan University, Damghan (Iran, Islamic Republic of); Mohammadipanah, Fatemeh [Department of Microbial Biotechnology, School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, 14155-6455 Tehran (Iran, Islamic Republic of); Ganjali, Mohammad Reza [Center of Excellence in Electrochemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Biosensor Research Center, Endocrinology & Metabolism Molecular and Cellular Research Institute, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

    2015-10-01

    A new strategy was introduced for ssDNA immobilization on a modified glassy carbon electrode. The electrode surface was modified using polyaniline and chemically reduced graphene oxide decorated cerium oxide nanoparticles (CeO{sub 2}NPs-RGO). A single-stranded DNA (ssDNA) probe was immobilized on the modified electrode surface. Fast Fourier transform square wave voltammetry (FFT-SWV) was applied as detection technique and [Ru(bpy){sub 3}]{sup 2+/3+} redox signal was used as electrochemical marker. The hybridization of ssDNA with its complementary target caused a dramatic decrease in [Ru(bpy){sub 3}]{sup 2+/3+} FFT-SW signal. The proposed electrochemical biosensor was able to detect Aeromonas hydrophila DNA oligonucleotide sequence encoding aerolysin protein. Under optimal conditions, the biosensor showed excellent selectivity toward complementary sequence in comparison with noncomplementary and two-base mismatch sequences. The dynamic linear range of this electrochemical DNA biosensor for detecting 20-mer oligonucleotide sequence of A. hydrophila was from 1 × 10{sup −15} to 1 × 10{sup −8} mol L{sup −1}. The proposed biosensor was successfully applied for the detection of DNA extracted from A. hydrophila in fish pond water up to 0.01 μg mL{sup −1} with RSD of 5%. Besides, molecular docking was applied to consider the [Ru(bpy){sub 3}]{sup 2+/3+} interaction with ssDNA before and after hybridization. - Highlights: • New DNA biosensor is designed for sub-femtomolar detection of Aeromonas hydrophila DNA sequence. • Reduced graphene oxide decorated Ceria nanoparticles was used as a new immobilization platform. • Biosensor was successfully used to detect A. hydrophila DNA sequence in fish pond water.

  7. Detection of Aeromonas hydrophila DNA oligonucleotide sequence using a biosensor design based on Ceria nanoparticles decorated reduced graphene oxide and Fast Fourier transform square wave voltammetry

    Jafari, Safiye; Faridbod, Farnoush; Norouzi, Parviz; Dezfuli, Amin Shiralizadeh; Ajloo, Davood; Mohammadipanah, Fatemeh; Ganjali, Mohammad Reza

    2015-01-01

    A new strategy was introduced for ssDNA immobilization on a modified glassy carbon electrode. The electrode surface was modified using polyaniline and chemically reduced graphene oxide decorated cerium oxide nanoparticles (CeO_2NPs-RGO). A single-stranded DNA (ssDNA) probe was immobilized on the modified electrode surface. Fast Fourier transform square wave voltammetry (FFT-SWV) was applied as detection technique and [Ru(bpy)_3]"2"+"/"3"+ redox signal was used as electrochemical marker. The hybridization of ssDNA with its complementary target caused a dramatic decrease in [Ru(bpy)_3]"2"+"/"3"+ FFT-SW signal. The proposed electrochemical biosensor was able to detect Aeromonas hydrophila DNA oligonucleotide sequence encoding aerolysin protein. Under optimal conditions, the biosensor showed excellent selectivity toward complementary sequence in comparison with noncomplementary and two-base mismatch sequences. The dynamic linear range of this electrochemical DNA biosensor for detecting 20-mer oligonucleotide sequence of A. hydrophila was from 1 × 10"−"1"5 to 1 × 10"−"8 mol L"−"1. The proposed biosensor was successfully applied for the detection of DNA extracted from A. hydrophila in fish pond water up to 0.01 μg mL"−"1 with RSD of 5%. Besides, molecular docking was applied to consider the [Ru(bpy)_3]"2"+"/"3"+ interaction with ssDNA before and after hybridization. - Highlights: • New DNA biosensor is designed for sub-femtomolar detection of Aeromonas hydrophila DNA sequence. • Reduced graphene oxide decorated Ceria nanoparticles was used as a new immobilization platform. • Biosensor was successfully used to detect A. hydrophila DNA sequence in fish pond water.

  8. Modified calcium oxide as stable solid base catalyst for Aldol

    A highly efficient and stable solid-base catalyst for Aldol condensation was prepared by modifying commercial CaO with benzyl bromide in a simple way. It was found that modified CaO can effectively catalyse the Aldol condensation of cyclohexanone and benzaldehyde, as well as various benzaldehydes, to produce ...

  9. Solvent-Free Selective Oxidation of Toluene with O2 Catalyzed by Metal Cation Modified LDHs and Mixed Oxides

    Xiaoli Wang

    2016-01-01

    Full Text Available A series of metal cation modified layered-double hydroxides (LDHs and mixed oxides were prepared and used to be the selective oxidation of toluene with O2. The results revealed that the modified LDHs exhibited much higher catalytic performance than their parent LDH and the modified mixed oxides. Moreover, the metal cations were also found to play important roles in the catalytic performance and stabilities of modified catalysts. Under the optimal reaction conditions, the highest toluene conversion reached 8.7% with 97.5% of the selectivity to benzyldehyde; moreover, the catalytic performance remained after nine catalytic runs. In addition, the reaction probably involved a free-radical mechanism.

  10. DNA extraction methods for detecting genetically modified foods: A comparative study.

    Elsanhoty, Rafaat M; Ramadan, Mohamed Fawzy; Jany, Klaus Dieter

    2011-06-15

    The work presented in this manuscript was achieved to compare six different methods for extracting DNA from raw maize and its derived products. The methods that gave higher yield and quality of DNA were chosen to detect the genetic modification in the samples collected from the Egyptian market. The different methods used were evaluated for extracting DNA from maize kernels (without treatment), maize flour (mechanical treatment), canned maize (sweet corn), frozen maize (sweet corn), maize starch, extruded maize, popcorn, corn flacks, maize snacks, and bread made from corn flour (mechanical and thermal treatments). The quality and quantity of the DNA extracted from the standards, containing known percentages of GMO material and from the different food products were evaluated. For qualitative detection of the GMO varieties in foods, the GMOScreen 35S/NOS test kit was used, to screen the genetic modification in the samples. The positive samples for the 35S promoter and/or the NOS terminator were identified by the standard methods adopted by EU. All of the used methods extracted yielded good DNA quality. However, we noted that the purest DNA extract were obtained using the DNA extraction kit (Roche) and this generally was the best method for extracting DNA from most of the maize-derived foods. We have noted that the yield of DNA extracted from maize-derived foods was generally lower in the processed products. The results indicated that 17 samples were positive for the presence of 35S promoter, while 34% from the samples were positive for the genetically modified maize line Bt-176. Copyright © 2010 Elsevier Ltd. All rights reserved.

  11. Nitric oxide-induced interstrand cross-links in DNA.

    Caulfield, Jennifer L; Wishnok, John S; Tannenbaum, Steven R

    2003-05-01

    The DNA damaging effects of nitrous acid have been extensively studied, and the formation of interstrand cross-links have been observed. The potential for this cross-linking to occur through a common nitrosating intermediate derived from nitric oxide is investigated here. Using a HPLC laser-induced fluorescence (LIF) system, the amount of interstrand cross-link formed on nitric oxide treatment of the 5'-fluorescein-labeled oligomer ATATCGATCGATAT was determined. This self-complimentary sequence contains two 5'-CG sequences, which is the preferred site for nitrous acid-induced cross-linking. Nitric oxide was delivered to an 0.5 mM oligomer solution at 15 nmol/mL/min to give a final nitrite concentration of 652 microM. The resulting concentration of the deamination product, xanthine, in this sample was found to be 211 +/- 39 nM, using GC/MS, and the amount of interstrand cross-link was determined to be 13 +/- 2.5 nM. Therefore, upon nitric oxide treatment, the cross-link is found at approximately 6% of the amount of the deamination product. Using this system, detection of the cross-link is also possible for significantly lower doses of nitric oxide, as demonstrated by treatment of the same oligomer with NO at a rate of 18 nmol/mL/min resulting in a final nitrite concentration of 126 microM. The concentration of interstrand cross-link was determined to be 3.6 +/- 0.1 nM in this sample. Therefore, using the same dose rate, when the total nitric oxide concentration delivered drops by a factor of approximately 5, the concentration of cross-link drops by a factor of about 4-indicating a qausi-linear response. It may now be possible to predict the number of cross-links in a small genome based on the number of CpG sequences and the yield of xanthine derived from nitrosative deamination.

  12. Simultaneous DPV determination of morphine and codeine using dsDNA modified screen printed electrode strips coupled with electromembrane extraction

    Rouhollah Feizbakhsh

    2016-01-01

    Full Text Available In this work a sensitive electrochemical sensor for simultaneous determination of morphine and codeine constructed by application of disposable screen printed carbon electrode strips (SPCE modified by double strand (ds calf thymus DNA. According to the results of the modified SPCE strips and experimented parameters, we observed a considerable shift between potentials of morphine and codeine current peaks. Related to these observed shifts, we studied on the effect of the concentration of modifier and pH value on the anodic oxidation pattern of morphine and codeine in the case of optimize the method to get better signals with maximum potential distance. Also to boosting the LODs of this electroanalytical method coupled with an electro-membrane preconcentration (EME step. The calibration curve which was plotted by the variation of differential pulse voltammetry (DPV currents as a function of different morphine and codeine concentration were linear within the range of 0.7– 40 µM and 2.3- 40 µM for morphine and codeine respectively. Also the limits of detection were 0.07 µM and 0.23 µM, respectively. Finally, the proposed method was able to determine morphine and codeine simultaneously and effectively in urinary real samples

  13. Fast repair of oxidizing OH adducts of DNA by hydroxycinnamic acid derivatives. A pulse radiolytic study

    Yue Jiang; Lin Weizhen; Yao Side; Lin Nianyun; Zhu Dayuan

    1999-01-01

    Using pulse radiolytic techniques, it has been demonstrated that the interactions of oxidizing OH adducts of DNA (ssDNA and dsDNA), polyA and polyG with hydroxycinnamic acid derivatives proceed via an electron transfer process (k=5-30x10 8 dm 3 mol -1 s -1 ). In addition, the rates for fast repair of OH adducts of dAMP, polyA and DNA (ssDNA and dsDNA) are slower than the corresponding rates for the rest OH adducts of DNA constituents. The slower rates for repair of oxidizing OH adducts of dAMP may be the rate determining step during the interaction of hydroxycinnamic acid derivatives with OH adducts of DNA containing the varieties of OH adducts of DNA constituents

  14. Modified method for combined DNA and RNA isolation from peanut and other oil seeds.

    Dang, Phat M; Chen, Charles Y

    2013-02-01

    Isolation of good quality RNA and DNA from seeds is difficult due to high levels of polysaccharides, polyphenols, and lipids that can degrade or co-precipitate with nucleic acids. Standard RNA extraction methods utilizing guanidinium-phenol-chloroform extraction has not shown to be successful. RNA isolation from plant seeds is a prerequisite for many seed specific gene expression studies and DNA is necessary in marker-assisted selection and other genetic studies. We describe a modified method to isolate both RNA and DNA from the same seed tissue and have been successful with several oil seeds including peanut, soybean, sunflower, canola, and oil radish. An additional LiCl precipitation step was added to isolate both RNA and DNA from the same seed tissues. High quality nucleic acids were observed based on A(260)/A(280) and A(260)/A(230) ratios above 2.0 and distinct bands on gel-electrophoresis. RNA was shown to be suitable for reverse transcriptase polymerase chain reaction based on actin or 60S ribosomal primer amplification and DNA was shown to have a single band on gel-electrophoresis analysis. This result shows that RNA and DNA isolated using this method can be appropriate for molecular studies in peanut and other oil containing seeds.

  15. Degradation of transgene DNA in genetically modified herbicide-tolerant rice during food processing.

    Song, Shangxin; Zhou, Guanghong; Gao, Feng; Zhang, Wei; Qiu, Liangyan; Dai, Sifa; Xu, Xinglian; Xiao, Hongmei

    2011-12-01

    In order to assess the effect of food processing on the degradation of exogenous DNA components in sweet rice wine and rice crackers made from genetically modified (GM) rice (Oryza sativa L.), we developed genomic DNA extraction methods and compared the effect of different food processing procedures on DNA degradation. It was found that the purity, quantity and quality of DNA by alkaline lysis method were higher than by CTAB (cetyltrimethylammonium bromide) method. For sweet rice wine, CAMV35S (cauliflower mosaic virus 35S) promoter and NOS (nopaline synthase) terminator were degraded by the third day, whereas the exogenous gene Bar (bialaphos resistance) remained unaffected. For rice crackers, boiling, drying and microwaving contributed to the initial degradations of DNA. Baking resulted in further degradations, and frying led to the most severe changes. These results indicated that the stability of DNA in GM rice was different under different processing conditions. For sweet rice wine, Bar was most stable, followed by NOS, CAMV35S, and SPS. For rice crackers, CAMV35S was most stable, followed by SPS, NOS, and Bar. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Redox-sensitive structural change in the A-domain of HMGB1 and its implication for the binding to cisplatin modified DNA

    Wang, Jing; Tochio, Naoya; Takeuchi, Aya; Uewaki, Jun-ichi; Kobayashi, Naohiro; Tate, Shin-ichi

    2013-01-01

    Highlights: •The structure of the oxidized A-domain of human HMGB1 was solved. •Phe38 ring was flipped in the oxidized structure from that in the reduced form. •The flipped ring disables the intercalation into the cisplatinated lesions. •The functionally relevant redox-dependent structural change was described. -- Abstract: HMGB1 (high-mobility group B1) is a ubiquitously expressed bifunctional protein that acts as a nuclear protein in cells and also as an inflammatory mediator in the extracellular space. HMGB1 changes its functions according to the redox states in both intra- and extra-cellular environments. Two cysteines, Cys23 and Cys45, in the A-domain of HMGB1 form a disulfide bond under oxidative conditions. The A-domain with the disulfide bond shows reduced affinity to cisplatin modified DNA. We have solved the oxidized A-domain structure by NMR. In the structure, Phe38 has a flipped ring orientation from that found in the reduced form; the phenyl ring in the reduced form intercalates into the platinated lesion in DNA. The phenyl ring orientation in the oxidized form is stabilized through intramolecular hydrophobic contacts. The reorientation of the Phe38 ring by the disulfide bond in the A-domain may explain the reduced HMGB1 binding affinity towards cisplatinated DNA

  17. Tissue response to intraperitoneal implants of polyethylene oxide-modified polyethylene terephthalate.

    Desai, N P; Hubbell, J A

    1992-01-01

    Polyethylene terephthalate films surface modified with polyethylene oxide of mol wt 18,500 g/mol (18.5 k) by a previously described technique, were implanted in the peritoneal cavity of mice, along with their respective untreated controls, for periods of 1-28 d. The implants were retrieved and examined for tissue reactivity and cellular adherence. The control polyethylene terephthalate surfaces showed an initial inflammatory reaction followed by an extensive fibrotic response with a mean thickness of 60 microns at 28 d. By contrast, polyethylene oxide-modified polyethylene terephthalate showed only a mild inflammatory response and no fibrotic encapsulation throughout the implantation period: at 28 d a cellular monolayer was observed. Apparently either the polyethylene oxide-modified surface was stimulating less inflammation, which was in turn stimulating less fibroblastic overgrowth, or the cellular adhesion to the polyethylene oxide-modified surface was too weak to support cellular multilayers.

  18. Direct voltammetric analysis of DNA modified with enzymatically incorporated 7-deazapurines

    Pivoňková, Hana; Horáková Brázdilová, Petra; Fojtová, Miloslava; Fojta, Miroslav

    2010-01-01

    Roč. 82, č. 16 (2010), s. 6807-6813 ISSN 0003-2700 R&D Projects: GA AV ČR(CZ) IAA400040901; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : modified DNA * 7-deazapurines * voltammetric analysis Subject RIV: BO - Biophysics Impact factor: 5.874, year: 2010

  19. Evaluation of oxidative DNA damage promoted by storage in sperm from sex-reversed rainbow trout.

    Pérez-Cerezales, S; Martínez-Páramo, S; Cabrita, E; Martínez-Pastor, F; de Paz, P; Herráez, M P

    2009-03-01

    Short-term storage and cryopreservation of sperm are two common procedures in aquaculture, used for routine practices in artificial insemination reproduction and gene banking, respectively. Nevertheless, both procedures cause injuries affecting sperm motility, viability, cell structure and DNA stability, which diminish reproductive success. DNA modification is considered extremely important, especially when sperm storage is carried out with gene banking purposes. DNA damage caused by sperm storage is not well characterized and previous studies have reported simple and double strand breaks that have been attributed to oxidative events promoted by the generation of free radicals during storage. The objective of this study was to reveal DNA fragmentation and to explore the presence of oxidized bases that could be produced by oxidative events during short-term storage and cryopreservation in sex-reversed rainbow trout (Oncorhynchus mykiss) spermatozoa. Sperm from six males was analyzed separately. Different aliquots of the samples were stored 2h (fresh) or 5 days at 4 degrees C or were cryopreserved. Then spermatozoa were analyzed using the Comet assay, as well as combining this method with digestion with two endonucleases from Escherichia coli (Endonuclease III, that cut in oxidized cytosines, and FPG, cutting in oxidized guanosines). Both storage procedures yielded DNA fragmentation, but only short-term storage oxidative events were clearly detected, showing that oxidative processes affect guanosines rather than cytosines. Cryopreservation increases DNA fragmentation but the presence of oxidized bases was not noticed, suggesting that mechanisms other than oxidative stress could be involved in DNA fragmentation promoted by freezing.

  20. Personal exposure to ultrafine particles and oxidative DNA damage

    Vinzents, Peter S; Møller, Peter; Sørensen, Mette

    2005-01-01

    Exposure to ultrafine particles (UFPs) from vehicle exhaust has been related to risk of cardiovascular and pulmonary disease and cancer, even though exposure assessment is difficult. We studied personal exposure in terms of number concentrations of UFPs in the breathing zone, using portable instr......, particularly during bicycling in traffic. The results indicate that biologic effects of UFPs occur at modest exposure, such as that occurring in traffic, which supports the relationship of UFPs and the adverse health effects of air pollution.......Exposure to ultrafine particles (UFPs) from vehicle exhaust has been related to risk of cardiovascular and pulmonary disease and cancer, even though exposure assessment is difficult. We studied personal exposure in terms of number concentrations of UFPs in the breathing zone, using portable...... instruments in six 18-hr periods in 15 healthy nonsmoking subjects. Exposure contrasts of outdoor pollution were achieved by bicycling in traffic for 5 days and in the laboratory for 1 day. Oxidative DNA damage was assessed as strand breaks and oxidized purines in mononuclear cells isolated from venous blood...

  1. Modified structure of graphene oxide by investigation of structure ...

    In this regard, GO was produced using the modified. Hummers method and ... erated in some regions due to hydrogen bonding between functional groups. Trapped water .... flakes were reacted with strong acid solution of H2SO4 and. HNO3.

  2. Polymer derived non-oxide ceramics modified with late transition metals.

    Zaheer, Muhammad; Schmalz, Thomas; Motz, Günter; Kempe, Rhett

    2012-08-07

    This tutorial review highlights the methods for the preparation of metal modified precursor derived ceramics (PDCs) and concentrates on the rare non-oxide systems enhanced with late transition metals. In addition to the main synthetic strategies for modified SiC and SiCN ceramics, an overview of the morphologies, structures and compositions of both, ceramic materials and metal (nano) particles, is presented. Potential magnetic and catalytic applications have been discussed for the so manufactured metal containing non-oxide ceramics.

  3. Modified surface of titanium dioxide nanoparticles-based biosensor for DNA detection

    Nadzirah, Sh.; Hashim, U.; Rusop, M.

    2018-05-01

    A new technique was used to develop a simple and selective picoammeter DNA biosensor for identification of E. coli O157:H7. This biosensor was fabricated from titanium dioxide nanoparticles that was synthesized by sol-gel method and spin-coated on silicon dioxide substrate via spinner. 3-Aminopropyl triethoxy silane (APTES) was used to modify the surface of TiO2. Simple surface modification approach has been applied; which is single dropping of APTES onto the TiO2 nanoparticles surface. Carboxyl modified probe DNA has been bind onto the surface of APTES/TiO2 without any amplifier element. Electrical signal has been used as the indicator to differentiate each step (surface modification of TiO2 and probe DNA immobilization). The I-V measurements indicate extremely low current (pico-ampere) flow through the device which is 2.8138E-10 A for pure TiO2 nanoparticles, 2.8124E-10 A after APTES modification and 3.5949E-10 A after probe DNA immobilization.

  4. Multicolour probes for sequence-specific DNA detection based on graphene oxide.

    Zhu, Qing; Xiang, Dongshan; Zhang, Cuiling; Ji, Xinghu; He, Zhike

    2013-09-21

    The bifunctionality of graphene oxide (GO) which can highly adsorb single-stranded DNA (ssDNA) and effectively quench the emission of organic dyes is reasonably utilized in a multiplexed DNA detection system, achieving sensitive and selective detection of HIV, VV and EV, respectively.

  5. Modified cermet fuel electrodes for solid oxide electrochemical cells

    Ruka, Roswell J.; Spengler, Charles J.

    1991-01-01

    An exterior porous electrode (10), bonded to a solid oxygen ion conducting electrolyte (13) which is in contact with an interior electrode (14), contains coarse metal particles (12) of nickel and/or cobalt, having diameters from 3 micrometers to 35 micrometers, where the coarse particles are coated with a separate, porous, multiphase layer (17) containing fine metal particles of nickel and/or cobalt (18), having diameters from 0.05 micrometers to 1.75 micrometers and conductive oxide (19) selected from cerium oxide, doped cerium oxide, strontium titanate, doped strontium titanate and mixtures thereof.

  6. Isolation/separation of plasmid DNA using hemoglobin modified magnetic nanocomposites as solid-phase adsorbent.

    Chen, Xu-Wei; Mao, Quan-Xing; Liu, Jia-Wei; Wang, Jian-Hua

    2012-10-15

    Hemoglobin (Hb) modified magnetic nanocomposites are prepared by immobilization of Hb onto the surface of amino-functionalized Fe(3)O(4)@SiO(2) magnetic nanoparticles via covalent bonding with glutaraldehyde as cross-linker. The obtained nanocomposites are characterized with FT-IR, SEM, XRD and surface charge analysis. A direct solid-phase extraction procedure for the isolation/separation of plasmid DNA using this nanocomposite as a novel adsorbent is thus developed. Some important experimental parameters governing the sorption efficiency, i.e., the pH of sample solution and the ionic strength, are investigated. The Hb modified magnetic nanocomposites provide a sorption capacity of 27.86 mg g(-1) for DNA. By using 2.0mg of the nanocomposites as sorption medium and a suitable acidity of pH 6.1, a sorption efficiency of 93% is achieved for 25 μg mL(-1) of DNA in 1.0 mL of sample solution. Afterwards, the absorbed DNA could be readily recovered by using 1.0 mL of Tris-HCl buffer (pH 8.9, 0.01 mol L(-1)), giving rise to a recovery of ca. 68.3%. The present solid-phased extraction protocol is applied for the isolation of plasmid DNA from Escherichia coli culture, resulting in comparable yield and purity of plasmid DNA with respect to those obtained by using commercial kits. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Exposure to 1800 MHz radiofrequency electromagnetic radiation induces oxidative DNA base damage in a mouse spermatocyte-derived cell line.

    Liu, Chuan; Duan, Weixia; Xu, Shangcheng; Chen, Chunhai; He, Mindi; Zhang, Lei; Yu, Zhengping; Zhou, Zhou

    2013-03-27

    Whether exposure to radiofrequency electromagnetic radiation (RF-EMR) emitted from mobile phones can induce DNA damage in male germ cells remains unclear. In this study, we conducted a 24h intermittent exposure (5 min on and 10 min off) of a mouse spermatocyte-derived GC-2 cell line to 1800 MHz Global System for Mobile Communication (GSM) signals in GSM-Talk mode at specific absorption rates (SAR) of 1 W/kg, 2 W/kg or 4 W/kg. Subsequently, through the use of formamidopyrimidine DNA glycosylase (FPG) in a modified comet assay, we determined that the extent of DNA migration was significantly increased at a SAR of 4 W/kg. Flow cytometry analysis demonstrated that levels of the DNA adduct 8-oxoguanine (8-oxoG) were also increased at a SAR of 4 W/kg. These increases were concomitant with similar increases in the generation of reactive oxygen species (ROS); these phenomena were mitigated by co-treatment with the antioxidant α-tocopherol. However, no detectable DNA strand breakage was observed by the alkaline comet assay. Taking together, these findings may imply the novel possibility that RF-EMR with insufficient energy for the direct induction of DNA strand breaks may produce genotoxicity through oxidative DNA base damage in male germ cells. Crown Copyright © 2013. Published by Elsevier Ireland Ltd. All rights reserved.

  8. Analysis of the relationships between oxidative stress, DNA damage and sperm vitality in a patient population: development of diagnostic criteria.

    Aitken, R John; De Iuliis, Geoffry N; Finnie, Jane M; Hedges, Andrew; McLachlan, Robert I

    2010-10-01

    DNA damage in human spermatozoa is known to be associated with a variety of adverse clinical outcomes affecting both reproductive efficiency and the health and wellbeing of the offspring. However, the origin of this damage, its biochemical nature and strategies for its amelioration, still await resolution. Using novel methods to simultaneously assess DNA fragmentation (modified TUNEL assay), DNA-base adduct formation (8-hydroxy-2'-deoxyguanosine [8OHdG]) and cell vitality, spermatozoa from a cohort of 50 assisted conception patients were examined and compared with a group of donors. Receiver operating characteristic (ROC) curve analysis was then used to examine the frequency distribution of the data and to determine optimized thresholds for identifying patients exhibiting abnormally high levels of DNA damage. 8OHdG formation and DNA fragmentation were highly correlated with each other and frequently associated with cell death. Percoll centrifugation improved sperm quality but, unexpectedly, increased 8OHdG formation in live cells, as did sperm fractionation using Puresperm gradients. ROC analysis indicated that the frequency distribution of 8OHdG and DNA fragmentation data were significantly different between patients and donors (P live cells. However, the development of novel methods and optimized thresholds for diagnosing oxidative DNA damage in human spermatozoa should assist in the clinical management of this pathology.

  9. Hg(2+) detection using a phosphorothioate RNA probe adsorbed on graphene oxide and a comparison with thymine-rich DNA.

    Huang, Po-Jung Jimmy; van Ballegooie, Courtney; Liu, Juewen

    2016-06-07

    Mercury is a highly toxic heavy metal and many DNA-based biosensors have been recently developed for Hg(2+) detection in water. Among them, thymine-rich DNA is the most commonly used for designing Hg(2+) sensors. However, the thymine-Hg(2+) interaction is strongly affected by the buffer conditions. We recently reported a molecular beacon containing phosphorothioate (PS)-modified RNA linkages that can be cleaved by Hg(2+). In this work, the fluorescence quenching and DNA adsorption properties of nano-sized graphene oxide (NGO) were used to develop a new sensor using the PS-RNA chemistry. Three DNA probes, containing one, three and five PS-RNA linkages, respectively, were tested. Finally, a fluorophore-labeled poly-A DNA with five PS-RNA linkages was selected and adsorbed by NGO. In the presence of Hg(2+), the fluorophore was released from NGO due to the cleavage reaction, resulting in a fluorescence enhancement. This sensor is highly selective for Hg(2+) with a detection limit of 8.5 nM Hg(2+). For comparison, a fluorophore-labeled poly-T DNA was also tested, which responded to Hg(2+) more slowly and was inhibited by high NaCl concentrations, while the PS-RNA probe was more tolerant to different buffer conditions. This work indicates a new method for interfacing DNA with NGO for Hg(2+) detection.

  10. GC-Rich Extracellular DNA Induces Oxidative Stress, Double-Strand DNA Breaks, and DNA Damage Response in Human Adipose-Derived Mesenchymal Stem Cells.

    Kostyuk, Svetlana; Smirnova, Tatiana; Kameneva, Larisa; Porokhovnik, Lev; Speranskij, Anatolij; Ershova, Elizaveta; Stukalov, Sergey; Izevskaya, Vera; Veiko, Natalia

    2015-01-01

    Cell free DNA (cfDNA) circulates throughout the bloodstream of both healthy people and patients with various diseases. CfDNA is substantially enriched in its GC-content as compared with human genomic DNA. Exposure of haMSCs to GC-DNA induces short-term oxidative stress (determined with H2DCFH-DA) and results in both single- and double-strand DNA breaks (comet assay and γH2AX, foci). As a result in the cells significantly increases the expression of repair genes (BRCA1 (RT-PCR), PCNA (FACS)) and antiapoptotic genes (BCL2 (RT-PCR and FACS), BCL2A1, BCL2L1, BIRC3, and BIRC2 (RT-PCR)). Under the action of GC-DNA the potential of mitochondria was increased. Here we show that GC-rich extracellular DNA stimulates adipocyte differentiation of human adipose-derived mesenchymal stem cells (haMSCs). Exposure to GC-DNA leads to an increase in the level of RNAPPARG2 and LPL (RT-PCR), in the level of fatty acid binding protein FABP4 (FACS analysis) and in the level of fat (Oil Red O). GC-rich fragments in the pool of cfDNA can potentially induce oxidative stress and DNA damage response and affect the direction of mesenchymal stem cells differentiation in human adipose-derived mesenchymal stem cells. Such a response may be one of the causes of obesity or osteoporosis.

  11. investigation of the effect of zinc oxide-modified gum arabic on polar ...

    BARTH EKWUEME

    Gum Arabic solution, a water-based adhesive, was modified with zinc oxide filler and the formulation was applied on wood, ceramic, glass and textile substrates. A strip of paper was used as a common adherent to all the substrates. Zinc oxide increased the viscosity of 30wt% gum Arabic solution and increased bond ...

  12. Investigation of the effect of zinc oxide-modified gum Arabic on polar ...

    Gum Arabic solution, a water-based adhesive, was modified with zinc oxide filler and the formulation was applied on wood, ceramic, glass and textile substrates. A strip of paper was used as a common adherent to all the substrates. Zinc oxide increased the viscosity of 30wt% gum Arabic solution and increased bond ...

  13. Dielectric properties of modified graphene oxide filled polyurethane nanocomposites and its correlation with rheology

    Sadasivuni, K.K.; Ponnamma, D.; Kumar, B.; Strankowski, M.; Cardinaels, R.M.; Moldenaers, P.; Thomas, S.; Grohens, Y.

    2014-01-01

    This study aims at investigating the dynamic mechanical, dielectric and rheological properties of reinforced polyurethane (PU) nanocomposites containing hydrophilic graphene oxide (GO) and/or hydrophobic modified graphene oxide (mGO) sheets. The organic modification of GO was performed with

  14. Sensing nitric oxide with a carbon nanofiber paste electrode modified with a CTAB and nafion composite

    Zheng, Dongyun; Liu, Xiaojun; Zhu, Shanying; Cao, Huimin; Chen, Yaguang; Hu, Shengshui

    2015-01-01

    We describe an electrochemical sensor for nitric oxide that was obtained by modifying the surface of a nanofiber carbon paste microelectrode with a film composed of hexadecyl trimethylammonium bromide and nafion. The modified microelectrode displays excellent catalytic activity in the electrochemical oxidation of nitric oxide. The mechanism was studied by scanning electron microscopy and cyclic voltammetry. Under optimal conditions, the oxidation peak current at a working voltage of 0.75 V (vs. SCE) is related to the concentration of nitric oxide in the 2 nM to 0.2 mM range, and the detection limit is as low as 2 nM (at an S/N ratio of 3). The sensor was successfully applied to the determination of nitric oxide released from mouse hepatocytes. (author)

  15. Direct on-chip DNA synthesis using electrochemically modified gold electrodes as solid support

    Levrie, Karen; Jans, Karolien; Schepers, Guy; Vos, Rita; Van Dorpe, Pol; Lagae, Liesbet; Van Hoof, Chris; Van Aerschot, Arthur; Stakenborg, Tim

    2018-04-01

    DNA microarrays have propelled important advancements in the field of genomic research by enabling the monitoring of thousands of genes in parallel. The throughput can be increased even further by scaling down the microarray feature size. In this respect, microelectronics-based DNA arrays are promising as they can leverage semiconductor processing techniques with lithographic resolutions. We propose a method that enables the use of metal electrodes for de novo DNA synthesis without the need for an insulating support. By electrochemically functionalizing gold electrodes, these electrodes can act as solid support for phosphoramidite-based synthesis. The proposed method relies on the electrochemical reduction of diazonium salts, enabling site-specific incorporation of hydroxyl groups onto the metal electrodes. An automated DNA synthesizer was used to couple phosphoramidite moieties directly onto the OH-modified electrodes to obtain the desired oligonucleotide sequence. Characterization was done via cyclic voltammetry and fluorescence microscopy. Our results present a valuable proof-of-concept for the integration of solid-phase DNA synthesis with microelectronics.

  16. Immunological detection and quantification of DNA components structurally modified by alkylating carcinogens, mutagens and chemotherapeutic agents

    Rajewsky, M.F.

    1983-01-01

    The detection and quantification of defined reaction products of chemical mutagens and carcinogens (and of many cancer chemotherapeutic agents) with DNA require highly sensitive analytical techniques. The exceptional capability of immunoglobulins to recognize subtle alterations of molecular structure (especially when monoclonal antibodies are used to maximize specificity), outstanding sensitivity of immunoanalysis by high-affinity antibodies, and the fact that radioactively-labelled agents are not required suggest the utility of a radioimmunoassay to recognize and quantitate alkylated DNA products. We have recently developed a set of high-affinity monoclonal antibodies (secreted by mouse x mouse as well as by rat x rat hybridomas; antibody affinity constants, 10 9 to > 10 10 lmol) specifically directed against several DNA alkylation products with possible relevance in relation to both mutagenesis and malignant transformation of mammalian cells. These alkylation products include 0 6 -N-butyldeoxyguanosine, and 0 4 -ethyldeoxythymidine. When used in a radioimmunassay, an antibody specific for 0 6 -ethyldeoxyguanosine, for example, will detect this product at an 0 6 -ethyldeoxyguanosine/deoxyguanosine molar ratio of approx. 3 x 10 -7 in a hydrolysate of 100 ug of DNA. The limit of detection can be lowered further if the respective alkyldeoxynucleosides are separated by HPLC from the DNA hydrolysate prior to the RIA. The anti-alkyldeoxynucleoside monoclonal antibodies can also be used to visualize, by immunostaining and fluorescence microscopy combined with electronic image intensification, specific alkylation products in the nuclear DNA of individual cells, and to localize structurally modified bases in double-stranded DNA molecules by transmission electron microscopy

  17. Phosphate adsorption using modified iron oxide-based sorbents

    Phosphate RemovalThis dataset is associated with the following publication:Lalley , J., C. Han , G. RamMohan , T. Speth , J. Garland , M. Nadagouda , and D. Dionysiou. Phosphate Removal using Modified Bayoxide®E33 Adsorption Media. WATER RESEARCH. Elsevier Science Ltd, New York, NY, USA, issue}: 96-107, (2015).

  18. Aneuploidogenic effects and DNA oxidation induced in vitro by differently sized gold nanoparticles

    Di Bucchianico S

    2014-05-01

    Full Text Available Sebastiano Di Bucchianico,1 Maria Rita Fabbrizi,1 Silvia Cirillo,1 Chiara Uboldi,1 Douglas Gilliland,2 Eugenia Valsami-Jones,3,4 Lucia Migliore11Department of Translational Research and New Technologies in Medicine and Surgery, Medical Genetics Unit, University of Pisa, Pisa, Italy; 2European Commission-Joint Research Centre, Institute for Health and Consumer Protection, NanoBioSciences Unit, Ispra, Italy; 3School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK; 4Earth Sciences, Natural History Museum, Cromwell Road, London, UKAbstract: Gold nanoparticles (Au NPs are used in many fields, including biomedical applications; however, no conclusive information on their potential cytotoxicity and genotoxicity mechanisms is available. For this reason, experiments in human primary lymphocytes and murine macrophages (Raw264.7 were performed exposing cells to spherical citrate-capped Au NPs with two different nominal diameters (5 nm and 15 nm. The proliferative activity, mitotic, apoptotic, and necrotic markers, as well as chromosomal damage were assessed by the cytokinesis-block micronucleus cytome assay. Fluorescence in situ hybridization with human and murine pancentromeric probes was applied to distinguish between clastogenic and aneuploidogenic effects. Our results indicate that 5 nm and 15 nm Au NPs are able to inhibit cell proliferation by apoptosis and to induce chromosomal damage, in particular chromosome mis-segregation. DNA strand breaks were detected by comet assay, and the modified protocol using endonuclease-III and formamidopyrimidine-DNA glycosylase restriction enzymes showed that pyrimidines and purines were oxidatively damaged by Au NPs. Moreover, we show a size-independent correlation between the cytotoxicity of Au NPs and their tested mass concentration or absolute number, and genotoxic effects which were more severe for Au NP 15 nm compared to Au NP 5 nm. Results indicate that

  19. Biomarkers of oxidative stress and DNA damage in agricultural workers: A pilot study

    Muniz, Juan F.; McCauley, Linda; Scherer, J.; Lasarev, M.; Koshy, M.; Kow, Y.W.; Nazar-Stewart, Valle; Kisby, G.E.

    2008-01-01

    Oxidative stress and DNA damage have been proposed as mechanisms linking pesticide exposure to health effects such as cancer and neurological diseases. A study of pesticide applicators and farmworkers was conducted to examine the relationship between organophosphate pesticide exposure and biomarkers of oxidative stress and DNA damage. Urine samples were analyzed for OP metabolites and 8-hydroxy-2'-deoxyguanosine (8-OH-dG). Lymphocytes were analyzed for oxidative DNA repair activity and DNA damage (Comet assay), and serum was analyzed for lipid peroxides (i.e., malondialdehyde, MDA). Cellular damage in agricultural workers was validated using lymphocyte cell cultures. Urinary OP metabolites were significantly higher in farmworkers and applicators (p < 0.001) when compared to controls. 8-OH-dG levels were 8.5 times and 2.3 times higher in farmworkers or applicators (respectively) than in controls. Serum MDA levels were 4.9 times and 24 times higher in farmworkers or applicators (respectively) than in controls. DNA damage (Comet assay) and oxidative DNA repair were significantly greater in lymphocytes from applicators and farmworkers when compared with controls. Markers of oxidative stress (i.e., increased reactive oxygen species and reduced glutathione levels) and DNA damage were also observed in lymphocyte cell cultures treated with an OP. The findings from these in vivo and in vitro studies indicate that organophosphate pesticides induce oxidative stress and DNA damage in agricultural workers. These biomarkers may be useful for increasing our understanding of the link between pesticides and a number of health effects

  20. Graphene oxide layers modified by light energetic ions

    Malinský, Petr; Macková, Anna; Mikšová, Romana; Kováčiková, Helena; Cutroneo, Mariapompea; Luxa, J.; Bouša, D.; Štrochová, B.; Sofer, Z.

    2017-01-01

    Roč. 19, č. 16 (2017), s. 10282-10291 ISSN 1463-9076 R&D Projects: GA ČR GA16-05167S; GA MŠk LM2015056 Institutional support: RVO:61389005 Keywords : graphene oxide * reduction * irradiation Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders OBOR OECD: Nuclear physics Impact factor: 4.123, year: 2016

  1. An ECVAG trial on assessment of oxidative damage to DNA measured by the comet assay

    Johansson, Clara; Møller, Peter; Forchhammer, Lykke

    2010-01-01

    The increasing use of single cell gel electrophoresis (the comet assay) highlights its popularity as a method for detecting DNA damage, including the use of enzymes for assessment of oxidatively damaged DNA. However, comparison of DNA damage levels between laboratories can be difficult due...... to differences in assay protocols (e.g. lysis conditions, enzyme treatment, the duration of the alkaline treatment and electrophoresis) and in the end points used for reporting results (e.g. %DNA in tail, arbitrary units, tail moment and tail length). One way to facilitate comparisons is to convert primary comet...... assay end points to number of lesions/10(6) bp by calibration with ionizing radiation. The aim of this study was to investigate the inter-laboratory variation in assessment of oxidatively damaged DNA by the comet assay in terms of oxidized purines converted to strand breaks with formamidopyrimidine DNA...

  2. The results of the lipids peroxidation products on the DNA bases as biological markers of the oxidative stress

    Falletti, O.

    2007-10-01

    Different ways of DNA damages have been studied, among these ones the direct way of DNA damages formation by the reactive oxygen species (R.O.S.). This way leads to the formation of oxidative DNA damages. In 1990, works have suggested an indirect way of DNA damages formation, the lipids peroxidation. Instead of oxidizing directly DNA, the R.O.S. oxide the lipids present in the cells and their membranes; The products coming from this degradation are able to provoke DNA damages. This way has not been studied very much. The work of this thesis is axed on this DNA theme and lipids peroxidation. In the first chapter, we begin by presenting DNA and the direct way of oxidative damages formation by the R.O.S.Then, we speak about the cell lipids suffering oxidation reactions and the different ways of lipids oxidation. Then, we present how the lipid peroxidation is a source of damages for DNA. (N.C.)

  3. Preparation of yttrium iron garnet (YIG) by modified domestic iron oxide

    Mozaffari, M.; Amighian

    2002-01-01

    Iron oxide by product of a local steel complex was modified to use for preparation of Yttrium iron garnet (YIG). The improvement was necessary to reduce impurities, especially the Si0 2 and Cl contents, which have deteriorative effects on magnetic properties and equipment used for preparation of the samples. The modified iron oxide was then mixed with Yttrium oxide of Merck Company in appropriate proportion to obtain a stoichiometric single phase YIG, using the conventional ceramic technique. XRD and SEM equipments were used to identify the resulting phases and microstructure respectively. Magnetic parameters were measured by VSM. Curie temperature of the samples was obtained by DTG (M) method. The results were compared with those obtained from samples that made by Merck iron oxide. There are small differences between the results. This was discussed according to extra pores and minute secondary phase in the samples made by domestic iron oxide. (Author)

  4. Hypoxia and oxidation levels of DNA and lipids in humans and animal experimental models

    Møller, Peter; Risom, Lotte; Lundby, Carsten

    2008-01-01

    The objective of this review was to evaluate the association between hypoxia and oxidative damage to DNA and lipids. Evaluation criteria encompassed specificity and validation status of the biomarkers, study design, strength of the association, dose-response relationship, biological plausibility......, analogous exposures, and effect modification by intervention. The collective interpretation indicates persuasive evidence from the studies in humans for an association between hypoxia and elevated levels of oxidative damage to DNA and lipids. The levels of oxidatively generated DNA lesions and lipid...... in subjects at high altitude. Most of the animal experimental models should be interpreted with caution because the assays for assessment of lipid peroxidation products have suboptimal validity....

  5. Carborane-linked 2'-deoxyuridine 5'-O-triphosphate as building block for polymerase synthesis of carborane-modified DNA.

    Balintová, Jana; Simonova, Anna; Białek-Pietras, Magdalena; Olejniczak, Agnieszka; Lesnikowski, Zbigniew J; Hocek, Michal

    2017-11-01

    5-[(p-Carborane-2-yl)ethynyl]-2'-deoxyuridine 5'-O-triphosphate was synthesized and used as a good substrate in enzymatic construction of carborane-modified DNA or oligonucleotides containing up to 21 carborane moieties in primer extension reactions by DNA polymerases. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Hydrogen peroxide biosensor based on DNA-Hb modified gold electrode

    Kafi, A.K.M.; Fan Yin; Shin, Hoon-Kyu; Kwon, Young-Soo

    2006-01-01

    A hydrogen peroxide (H 2 O 2 ) biosensor based on DNA-hemoglobin (Hb) modified electrode is described in this paper. The sensor was designed by DNA and hemoglobin dropletting onto gold electrode surface layer by layer. The sensor based on the direct electron transfer of iron of hemoglobin showed a well electrocatalytic response to the reduction of the H 2 O 2 . This sensor offered an excellent electrochemical response for H 2 O 2 concentration below micromole level with high sensitivity and selectivity and short response time. Experimental conditions influencing the biosensor performance such as, pH, potential were optimized and assessed. The levels of the RSD's ( 2 O 2 was observed from 10 to 120 μM with the detection limit of 0.4 μM (based on the S/N = 3)

  7. [Examination of processed vegetable foods for the presence of common DNA sequences of genetically modified tomatoes].

    Kitagawa, Mamiko; Nakamura, Kosuke; Kondo, Kazunari; Ubukata, Shoji; Akiyama, Hiroshi

    2014-01-01

    The contamination of processed vegetable foods with genetically modified tomatoes was investigated by the use of qualitative PCR methods to detect the cauliflower mosaic virus 35S promoter (P35S) and the kanamycin resistance gene (NPTII). DNA fragments of P35S and NPTII were detected in vegetable juice samples, possibly due to contamination with the genomes of cauliflower mosaic virus infecting juice ingredients of Brassica species and soil bacteria, respectively. Therefore, to detect the transformation construct sequences of GM tomatoes, primer pairs were designed for qualitative PCR to specifically detect the border region between P35S and NPTII, and the border region between nopaline synthase gene promoter and NPTII. No amplification of the targeted sequences was observed using genomic DNA purified from the juice ingredients. The developed qualitative PCR method is considered to be a reliable tool to check contamination of products with GM tomatoes.

  8. Fabrication of endothelial progenitor cell capture surface via DNA aptamer modifying dopamine/polyethyleneimine copolymer film

    Li, Xin; Deng, Jinchuan; Yuan, Shuheng; Wang, Juan; Luo, Rifang; Chen, Si [Key Lab. of Advanced Technology for Materials of Education Ministry, Southwest Jiaotong University, Chengdu 610031 (China); School of Material Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Wang, Jin, E-mail: jinxxwang@263.net [Key Lab. of Advanced Technology for Materials of Education Ministry, Southwest Jiaotong University, Chengdu 610031 (China); Huang, Nan [Key Lab. of Advanced Technology for Materials of Education Ministry, Southwest Jiaotong University, Chengdu 610031 (China); School of Material Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China)

    2016-11-15

    Highlights: • The dopamine/PEI film with controlled amine density was successfully prepared. • The DNA aptamer was assembled onto the film via electrostatic incorporation. • The A@DPfilmscanspecificallyandeffectivelycaptureEPCs. • The A@DP film can support the survival of ECs, control the hyperplasia of SMCs. • The dynamic/co-culture models are useful for studying cells competitive adhesion. - Abstract: Endothelial progenitor cells (EPCs) are mainly located in bone marrow and circulate, and play a crucial role in repairmen of injury endothelium. One of the most promising strategies of stents designs were considered to make in-situ endothelialization in vivo via EPC-capture biomolecules on a vascular graft to capture EPCs directly from circulatory blood. In this work, an EPC specific aptamer with a 34 bases single strand DNA sequence was conjugated onto the stent surface via dopamine/polyethyleneimine copolymer film as a platform and linker. The assembled density of DNA aptamer could be regulated by controlling dopamine percentage in this copolymer film. X-ray photoelectron spectroscopy (XPS), water contact angle (WCA) and fluorescence test confirmed the successful immobilization of DNA aptamer. To confirm its biofunctionality and cytocompatibility, the capturing cells ability of the aptamer modified surface and the effects on the growth behavior of human umbilical vein endothelial cells (HUVECs), smooth muscle cells (SMCs) were investigated. The aptamer functionalized sample revealed a good EPC-capture ability, and had a cellular friendly feature for both EPC and EC growth, while not stimulated the hyperplasia of SMCs. And, the co-culture experiment of three types of cells confirmed the specificity capturing of EPCs to aptamer modified surface, rather than ECs and SMCs. These data suggested that this aptamer functionalized surface may have a large potentiality for the application of vascular grafts with targeted endothelialization.

  9. Fabrication of endothelial progenitor cell capture surface via DNA aptamer modifying dopamine/polyethyleneimine copolymer film

    Li, Xin; Deng, Jinchuan; Yuan, Shuheng; Wang, Juan; Luo, Rifang; Chen, Si; Wang, Jin; Huang, Nan

    2016-01-01

    Highlights: • The dopamine/PEI film with controlled amine density was successfully prepared. • The DNA aptamer was assembled onto the film via electrostatic incorporation. • The A@DPfilmscanspecificallyandeffectivelycaptureEPCs. • The A@DP film can support the survival of ECs, control the hyperplasia of SMCs. • The dynamic/co-culture models are useful for studying cells competitive adhesion. - Abstract: Endothelial progenitor cells (EPCs) are mainly located in bone marrow and circulate, and play a crucial role in repairmen of injury endothelium. One of the most promising strategies of stents designs were considered to make in-situ endothelialization in vivo via EPC-capture biomolecules on a vascular graft to capture EPCs directly from circulatory blood. In this work, an EPC specific aptamer with a 34 bases single strand DNA sequence was conjugated onto the stent surface via dopamine/polyethyleneimine copolymer film as a platform and linker. The assembled density of DNA aptamer could be regulated by controlling dopamine percentage in this copolymer film. X-ray photoelectron spectroscopy (XPS), water contact angle (WCA) and fluorescence test confirmed the successful immobilization of DNA aptamer. To confirm its biofunctionality and cytocompatibility, the capturing cells ability of the aptamer modified surface and the effects on the growth behavior of human umbilical vein endothelial cells (HUVECs), smooth muscle cells (SMCs) were investigated. The aptamer functionalized sample revealed a good EPC-capture ability, and had a cellular friendly feature for both EPC and EC growth, while not stimulated the hyperplasia of SMCs. And, the co-culture experiment of three types of cells confirmed the specificity capturing of EPCs to aptamer modified surface, rather than ECs and SMCs. These data suggested that this aptamer functionalized surface may have a large potentiality for the application of vascular grafts with targeted endothelialization.

  10. One simple DNA extraction device and its combination with modified visual loop-mediated isothermal amplification for rapid on-field detection of genetically modified organisms.

    Zhang, Miao; Liu, Yinan; Chen, Lili; Quan, Sheng; Jiang, Shimeng; Zhang, Dabing; Yang, Litao

    2013-01-02

    Quickness, simplicity, and effectiveness are the three major criteria for establishing a good molecular diagnosis method in many fields. Herein we report a novel detection system for genetically modified organisms (GMOs), which can be utilized to perform both on-field quick screening and routine laboratory diagnosis. In this system, a newly designed inexpensive DNA extraction device was used in combination with a modified visual loop-mediated isothermal amplification (vLAMP) assay. The main parts of the DNA extraction device included a silica gel membrane filtration column and a modified syringe. The DNA extraction device could be easily operated without using other laboratory instruments, making it applicable to an on-field GMO test. High-quality genomic DNA (gDNA) suitable for polymerase chain reaction (PCR) and isothermal amplification could be quickly isolated from plant tissues using this device within 15 min. In the modified vLAMP assay, a microcrystalline wax encapsulated detection bead containing SYBR green fluorescent dye was introduced to avoid dye inhibition and cross-contaminations from post-LAMP operation. The system was successfully applied and validated in screening and identification of GM rice, soybean, and maize samples collected from both field testing and the Grain Inspection, Packers, and Stockyards Administration (GIPSA) proficiency test program, which demonstrated that it was well-adapted to both on-field testing and/or routine laboratory analysis of GMOs.

  11. An empirical study on the preparation of the modified coke and its catalytic oxidation properties

    Liu, Hao; Jiang, Wenqiang

    2017-05-01

    T As a methyl acrylic ester fungicide, pyraclostrobin has the advantages of high activity, wide sterilization spectrum and high safety level comparing with the traditional fungicide. Due to less toxicity and side effects on human and environment, the use of pyraclostrobin and its mixture in agriculture is increasing. The heavy use of pyraclostrobin will inevitably cause pollution to the biological and abiotic environment. Therefore, it is of great significance to do the research on the degradation of pyraclostrobin. In this study, coke, as matrix, was modified by chemical modification. The modified coke was used as the catalyst and the pyraclostrobin was used as the degradation object. The degradation experiment of pyraclostrobin was carried out by using catalytic oxidation. The catalytic oxidation performance of modified coke was studied. The result showed that in the catalytic oxidation system of using modified coke as catalyst and H2O2 as oxidant, the best reaction condition is as following: The modified coke which is modified by using 70% concentration nitric acid is used as catalyst; The dosage of the catalyst is10g; The dosage of H2O2 is 0.6ml; The reaction time is 6 hours.

  12. Design of a DNA chip for detection of unknown genetically modified organisms (GMOs).

    Nesvold, Håvard; Kristoffersen, Anja Bråthen; Holst-Jensen, Arne; Berdal, Knut G

    2005-05-01

    Unknown genetically modified organisms (GMOs) have not undergone a risk evaluation, and hence might pose a danger to health and environment. There are, today, no methods for detecting unknown GMOs. In this paper we propose a novel method intended as a first step in an approach for detecting unknown genetically modified (GM) material in a single plant. A model is designed where biological and combinatorial reduction rules are applied to a set of DNA chip probes containing all possible sequences of uniform length n, creating probes capable of detecting unknown GMOs. The model is theoretically tested for Arabidopsis thaliana Columbia, and the probabilities for detecting inserts and receiving false positives are assessed for various parameters for this organism. From a theoretical standpoint, the model looks very promising but should be tested further in the laboratory. The model and algorithms will be available upon request to the corresponding author.

  13. Lymphocyte DNA damage and oxidative stress in patients with iron deficiency anemia.

    Aslan, Mehmet; Horoz, Mehmet; Kocyigit, Abdurrahim; Ozgonül, Saadet; Celik, Hakim; Celik, Metin; Erel, Ozcan

    2006-10-10

    Oxidant stress has been shown to play an important role in the pathogenesis of iron deficiency anemia. The aim of this study was to investigate the association between lymphocyte DNA damage, total antioxidant capacity and the degree of anemia in patients with iron deficiency anemia. Twenty-two female with iron deficiency anemia and 22 healthy females were enrolled in the study. Peripheral DNA damage was assessed using alkaline comet assay and plasma total antioxidant capacity was determined using an automated measurement method. Lymphocyte DNA damage of patients with iron deficiency anemia was significantly higher than controls (ptotal antioxidant capacity was significantly lower (ptotal antioxidant capacity and hemoglobin levels (r=0.706, ptotal antioxidant capacity and hemoglobin levels were negatively correlated with DNA damage (r=-0.330, p<0.05 and r=-0.323, p<0.05, respectively). In conclusion, both oxidative stress and DNA damage are increased in IDA patients. Increased oxidative stress seems as an important factor that inducing DNA damage in those IDA patients. The relationships of oxidative stress and DNA damage with the severity of anemia suggest that both oxidative stress and DNA damage may, in part, have a role in the pathogenesis of IDA.

  14. Hide and seek: How do DNA glycosylases locate oxidatively damaged DNA bases amidst a sea of undamaged bases?

    Lee, Andrea J; Wallace, Susan S

    2017-06-01

    The first step of the base excision repair (BER) pathway responsible for removing oxidative DNA damage utilizes DNA glycosylases to find and remove the damaged DNA base. How glycosylases find the damaged base amidst a sea of undamaged bases has long been a question in the BER field. Single molecule total internal reflection fluorescence microscopy (SM TIRFM) experiments have allowed for an exciting look into this search mechanism and have found that DNA glycosylases scan along the DNA backbone in a bidirectional and random fashion. By comparing the search behavior of bacterial glycosylases from different structural families and with varying substrate specificities, it was found that glycosylases search for damage by periodically inserting a wedge residue into the DNA stack as they redundantly search tracks of DNA that are 450-600bp in length. These studies open up a wealth of possibilities for further study in real time of the interactions of DNA glycosylases and other BER enzymes with various DNA substrates. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. The single-strand DNA binding activity of human PC4 preventsmutagenesis and killing by oxidative DNA damage

    Wang, Jen-Yeu; Sarker, Altaf Hossain; Cooper, Priscilla K.; Volkert, Michael R.

    2004-02-01

    Human positive cofactor 4 (PC4) is a transcriptional coactivator with a highly conserved single-strand DNA (ssDNA) binding domain of unknown function. We identified PC4 as a suppressor of the oxidative mutator phenotype of the Escherichia coli fpg mutY mutant and demonstrate that this suppression requires its ssDNA binding activity. Yeast mutants lacking their PC4 ortholog Sub1 are sensitive to hydrogen peroxide and exhibit spontaneous and peroxide induced hypermutability. PC4 expression suppresses the peroxide sensitivity of the yeast sub l{Delta} mutant, suggesting that the human protein has a similar function. A role for yeast and human proteins in DNA repair is suggested by the demonstration that Sub1 acts in a peroxide-resistance pathway involving Rad2 and by the physical interaction of PC4 with the human Rad2 homolog XPG. We show XPG recruits PC4 to a bubble-containing DNA substrate with resulting displacement of XPG and formation of a PC4-DNA complex. We discuss the possible requirement for PC4 in either global or transcription-coupled repair of oxidative DNA damage to mediate the release of XPG bound to its substrate.

  16. Redox Response of Reduced Graphene Oxide-Modified Glassy Carbon Electrodes to Hydrogen Peroxide and Hydrazine

    Jun-ichi Anzai

    2013-05-01

    Full Text Available The surface of a glassy carbon (GC electrode was modified with reduced graphene oxide (rGO to evaluate the electrochemical response of the modified GC electrodes to hydrogen peroxide (H2O2 and hydrazine. The electrode potential of the GC electrode was repeatedly scanned from −1.5 to 0.6 V in an aqueous dispersion of graphene oxide (GO to deposit rGO on the surface of the GC electrode. The surface morphology of the modified GC electrode was characterized by scanning electron microscopy (SEM and atomic force microscopy (AFM. SEM and AFM observations revealed that aggregated rGO was deposited on the GC electrode, forming a rather rough surface. The rGO-modified electrodes exhibited significantly higher responses in redox reactions of H2O2 as compared with the response of an unmodified GC electrode. In addition, the electrocatalytic activity of the rGO-modified electrode to hydrazine oxidation was also higher than that of the unmodified GC electrode. The response of the rGO-modified electrode was rationalized based on the higher catalytic activity of rGO to the redox reactions of H2O2 and hydrazine. The results suggest that rGO-modified electrodes are useful for constructing electrochemical sensors.

  17. Modifying zirconia solid electrolyte surface property to enhance oxide transport

    Liaw, B.Y.; Song, S.Y. [Univ. of Hawaii, Honolulu, HI (United States)

    1996-12-31

    Bismuth-strontium-calcium-copper oxide (Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, BSCCO) is known for its high T{sub c} superconducting behavior and mixed conducting property. The applicability of similar high T{sub c} cuprates for intermediate-temperature solid oxide fuel cell (SOFC) application has been studied recently. We investigated the electrochemical behavior of several Ag{vert_bar}BSCCO{vert_bar}10 mol% yttria-stabilized zirconia (YSZ){vert_bar}Ag and Ag{vert_bar}YSZ{vert_bar}Ag cells using complex impedance spectroscopy. A highly uniform and porous microstructure was observed at the interface of the YSZ and BSCCO. The ionic conductivity determined from the Nyquest plots in the temperature range of 200-700{degrees}C agrees with the values reported in the literature. The specific resistance of the BSCCO{vert_bar}YSZ interface was also determined to be lower than those of the conventional manganite electrode, suggesting that BSCCO seems attractive for cathode applications in SOFC.

  18. DNA damage and oxidative stress in marine gastropod Morula granulata exposed to phenanthrene

    Bhagat, J.; Sarkar, A.; Ingole, B.S.

    oxidative stress was assessed using a battery of biomarkers such as glutathione-S-transferase (GST), catalase (CAT), and lipid peroxidation (LPO). Our data showed concentration-dependent increase in percentage DNA in tail (TDNA), LPO, and GST activity...

  19. Oxidative DNA damage in lung tissue from patients with COPD is clustered in functionally significant sequences

    Viktor M Pastukh

    2011-03-01

    Full Text Available Viktor M Pastukh1, Li Zhang2, Mykhaylo V Ruchko1, Olena Gorodnya1, Gina C Bardwell1, Rubin M Tuder2, Mark N Gillespie11Department of Pharmacology and Center for Lung Biology, University of South Alabama College of Medicine, Mobile, AL, USA; 2Program in Translational Lung Research, Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado at Denver, Aurora, CO, USAAbstract: Lung tissue from COPD patients displays oxidative DNA damage. The present study determined whether oxidative DNA damage was randomly distributed or whether it was localized in specific sequences in either the nuclear or mitochondrial genomes. The DNA damage-specific histone, gamma-H2AX, was detected immunohistochemically in alveolar wall cells in lung tissue from COPD patients but not control subjects. A PCR-based method was used to search for oxidized purine base products in selected 200 bp sequences in promoters and coding regions of the VEGF, TGF-β1, HO-1, Egr1, and β-actin genes while quantitative Southern blot analysis was used to detect oxidative damage to the mitochondrial genome in lung tissue from control subjects and COPD patients. Among the nuclear genes examined, oxidative damage was detected in only 1 sequence in lung tissue from COPD patients: the hypoxic response element (HRE of the VEGF promoter. The content of VEGF mRNA also was reduced in COPD lung tissue. Mitochondrial DNA content was unaltered in COPD lung tissue, but there was a substantial increase in mitochondrial DNA strand breaks and/or abasic sites. These findings show that oxidative DNA damage in COPD lungs is prominent in the HRE of the VEGF promoter and in the mitochondrial genome and raise the intriguing possibility that genome and sequence-specific oxidative DNA damage could contribute to transcriptional dysregulation and cell fate decisions in COPD.Keywords: DNA damage, VEGF hypoxic response element, mtDNA, COPD

  20. Humidity Sensing Properties of Surface Modified Polyaniline Metal Oxide Composites

    S. C. Nagaraju

    2014-01-01

    Full Text Available Polyaniline- (PANI praseodymium Oxide (Pr2O3 composites have been synthesized by in situ polymerization method with different weight percentages. The synthesized composites have been characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The temperature dependent conductivity shows that the conductivity is due to the hopping of polarons and bipolarons. These composites show negative thermal coefficient (α behavior as a function of temperature, which is characteristic behavior of semiconducting materials. Sensor studies have been carried out by two-probe method and found that the sensitivity increases with increase in % RH. It is noticed that stability increase is due to the presence of Pr2O3 in polyaniline up to 30 wt%. A fast recovery and response time along with high sensitivity make these composites suitable for humidity sensors.

  1. Is the Oxidative DNA Damage Level of Human Lymphocyte Correlated with the Antioxidant Capacity of Serum or the Base Excision Repair Activity of Lymphocyte?

    Yi-Chih Tsai

    2013-01-01

    Full Text Available A random screening of human blood samples from 24 individuals of nonsmoker was conducted to examine the correlation between the oxidative DNA damage level of lymphocytes and the antioxidant capacity of serum or the base excision repair (BER activity of lymphocytes. The oxidative DNA damage level was measured with comet assay containing Fpg/Endo III cleavage, and the BER activity was estimated with a modified comet assay including nuclear extract of lymphocytes for enzymatic cleavage. Antioxidant capacity was determined with trolox equivalent antioxidant capacity assay. We found that though the endogenous DNA oxidation levels varied among the individuals, each individual level appeared to be steady for at least 1 month. Our results indicate that the oxidative DNA damage level is insignificantly or weakly correlated with antioxidant capacity or BER activity, respectively. However, lymphocytes from carriers of Helicobacter pylori (HP or Hepatitis B virus (HBV tend to give higher levels of oxidative DNA damage (P<0.05. Though sera of this group of individuals show no particular tendency with reduced antioxidant capacity, the respective BER activities of lymphocytes are lower in average (P<0.05. Thus, reduction of repair activity may be associated with the genotoxic effect of HP or HBV infection.

  2. Characterization of surfactant/hydrotalcite-like clay/glassy carbon modified electrodes: Oxidation of phenol

    Hernandez, Maria; Fernandez, Lenys; Borras, Carlos; Mostany, Jorge; Carrero, Hermes

    2007-01-01

    The characteristics of hydrotalcite (HT)-like clay films containing ionic and nonionic surfactants and their ability to oxidize phenol have been examined. The HT clay (Co/Al-NO 3 ) was synthesized by coprecipitation techniques and then modified with surfactants such as sodium dodecylbenzenesulfonate (SDBS), octylphenoxypolyethoxyethanol (TX100) or cetylpyridinium bromide (CPB). X-ray diffraction analysis revealed that the interlayer basal spacing varied depending on the type of surfactant retained by the HT. The presence of SDBS and CPB expanded the HT interlayer, which in the presence of TX100 did not show an appreciable change. Phenol oxidation is favored at surfactant-HT-GC modified electrodes, after a preconcentration time, compared to phenol oxidation at HT-GC or GC electrodes. Surfactant-HT-GC modified electrodes display good stability in continuous electrochemical phenol oxidation. At pH values between 6 and 10.8, both SDBS-HT-GC and TX100-HT-GC modified electrodes seem to be promising electrodes for the detection of phenol in water; while the CPB-HT-GC modified electrode should be affected by the inorganic anions

  3. Overexpression of DNA ligase III in mitochondria protects cells against oxidative stress and improves mitochondrial DNA base excision repair

    Akbari, Mansour; Keijzers, Guido; Maynard, Scott

    2014-01-01

    slower than the preceding mitochondrial BER steps. Overexpression of DNA ligase III in mitochondria improved the rate of overall BER, increased cell survival after menadione induced oxidative stress and reduced autophagy following the inhibition of the mitochondrial electron transport chain complex I...

  4. Peroxiredoxin 1 Protects Telomeres from Oxidative Damage and Preserves Telomeric DNA for Extension by Telomerase

    Eric Aeby

    2016-12-01

    Full Text Available Oxidative damage of telomeres can promote cancer, cardiac failure, and muscular dystrophy. Specific mechanisms protecting telomeres from oxidative damage have not been described. We analyzed telomeric chromatin composition during the cell cycle and show that the antioxidant enzyme peroxiredoxin 1 (PRDX1 is enriched at telomeres during S phase. Deletion of the PRDX1 gene leads to damage of telomeric DNA upon oxidative stress, revealing a protective function of PRDX1 against oxidative damage at telomeres. We also show that the oxidized nucleotide 8-oxo-2′deoxyguanosine-5′-triphosphate (8oxodGTP causes premature chain termination when incorporated by telomerase and that some DNA substrates terminating in 8oxoG prevent extension by telomerase. Thus, PRDX1 safeguards telomeres from oxygen radicals to counteract telomere damage and preserve telomeric DNA for elongation by telomerase.

  5. GC-Rich Extracellular DNA Induces Oxidative Stress, Double-Strand DNA Breaks, and DNA Damage Response in Human Adipose-Derived Mesenchymal Stem Cells

    Svetlana Kostyuk

    2015-01-01

    Full Text Available Background. Cell free DNA (cfDNA circulates throughout the bloodstream of both healthy people and patients with various diseases. CfDNA is substantially enriched in its GC-content as compared with human genomic DNA. Principal Findings. Exposure of haMSCs to GC-DNA induces short-term oxidative stress (determined with H2DCFH-DA and results in both single- and double-strand DNA breaks (comet assay and γH2AX, foci. As a result in the cells significantly increases the expression of repair genes (BRCA1 (RT-PCR, PCNA (FACS and antiapoptotic genes (BCL2 (RT-PCR and FACS, BCL2A1, BCL2L1, BIRC3, and BIRC2 (RT-PCR. Under the action of GC-DNA the potential of mitochondria was increased. Here we show that GC-rich extracellular DNA stimulates adipocyte differentiation of human adipose-derived mesenchymal stem cells (haMSCs. Exposure to GC-DNA leads to an increase in the level of RNAPPARG2 and LPL (RT-PCR, in the level of fatty acid binding protein FABP4 (FACS analysis and in the level of fat (Oil Red O. Conclusions. GC-rich fragments in the pool of cfDNA can potentially induce oxidative stress and DNA damage response and affect the direction of mesenchymal stem cells differentiation in human adipose—derived mesenchymal stem cells. Such a response may be one of the causes of obesity or osteoporosis.

  6. Identification of genetically modified DNA found in Roundup Ready soybean using gold nanoparticles

    Jang, Huisoo; Kwak, Cheol Hwan; Kim, Gibum; Kim, Sun Min; Huh, Yun Suk; Jeon, Tae-Joon

    2016-01-01

    The authors describe an SPR sensor chip coated with gold nanoparticles (AuNPs) that enables highly sensitive determination of genetically modified (GM) crops. Detection is based on localized surface plasmon resonance (LSPR) with its known sensitivity to even minute changes in refractive index. The device consists of a halogen light source, a light detector, and a cuvette cell that contains a sensor chip coated with AuNPs. It is operated in the transmission mode of the optical path to enhance the plasmonic signal. The sample solution containing target DNA (e.g. from the GM crop) is introduced into the cuvette with the sensor chip whose surface was functionalized with a capture DNA. Following a 30-min hybridization, the changes of the signal are recorded at 540 nm. The chip responds to target DNA in the 1 to 100 nM concentration range and has a 1 nM detection limit. Features of this sensor chip include a short reaction time, ease of handling, and portability, and this enables on-site detection and in-situ testing. (author)

  7. POLYPYRROLE COATED CELLULOSIC SUBSTRATE MODIFIED BY COPPER OXIDE AS ELECTRODE FOR NITRATE ELECTROREDUCTION

    A. HAMAM; D. OUKIL; A. DIB; H. HAMMACHE; L. MAKHLOUFI; B. SAIDANI

    2015-01-01

    The aim of this work is to synthesize polypyrrole (PPy) films on nonconducting cellulosic substrate and modified by copper oxide particles for use in the nitrate electroreduction process. Firstly, the chemical polymerization of polypyrrole onto cellulosic substrate is conducted by using FeCl3 as an oxidant and pyrrole as monomer. The thickness and topography of the different PPy films obtained were estimated using a profilometer apparatus. The electrochemical reactivity of the obtained electr...

  8. Active Bilayer PE/PCL Films for Food Packaging Modified with Zinc Oxide and Casein

    Rešček, Ana; Kratofil Krehula, Ljerka; Katančić, Zvonimir; Hrnjak-Murgić, Zlata

    2015-01-01

    This paper studies the properties of active polymer food packaging bilayer polyethylene/polycaprolactone (PE/PCL) films. Such packaging material consists of primary PE layer coated with thin film of PCL coating modified with active component (zinc oxide or zinc oxide/casein complex) with intention to extend the shelf life of food and to maintain the quality and health safety. The influence of additives as active components on barrier, mechanical, thermal and antimicrobial properties of such m...

  9. Stwl modifies chromatin compaction and is required to maintain DNA integrity in the presence of perturbed DNA replication

    Yi, X.; Vries, de H.I.; Siudeja, K.; Rana, A.; Lemstra, W.; Brunsting, J.F.; Kok, R.J.M.; Smulders, Y.M.; Schaefer, M.; Dijk, F.; Shang, Y.F.; Eggen, B.J.L.; Kampinga, H.H.; Sibon, O.C.M.

    2009-01-01

    Hydroxyurea, a well-known DNA replication inhibitor, induces cell cycle arrest and intact checkpoint functions are required to survive DNA replication stress induced by this genotoxic agent. Perturbed DNA synthesis also results in elevated levels of DNA damage. It is unclear how organisms prevent

  10. Stwl Modifies Chromatin Compaction and Is Required to Maintain DNA Integrity in the Presence of Perturbed DNA Replication

    Yi, Xia; Vries, Hilda I. de; Siudeja, Katarzyna; Rana, Anil; Lemstra, Willy; Brunsting, Jeanette F.; Kok, Rob M.; Smulders, Yvo M.; Schaefer, Matthias; Dijk, Freark; Shang, Yongfeng; Eggen, Bart J.L.; Kampinga, Harm H.; Sibon, Ody C.M.

    Hydroxyurea, a well-known DNA replication inhibitor, induces cell cycle arrest and intact checkpoint functions are required to survive DNA replication stress induced by this genotoxic agent. Perturbed DNA synthesis also results in elevated levels of DNA damage. It is unclear how organisms prevent

  11. Oxidatively-induced DNA damage and base excision repair in euthymic patients with bipolar disorder.

    Ceylan, Deniz; Tuna, Gamze; Kirkali, Güldal; Tunca, Zeliha; Can, Güneş; Arat, Hidayet Ece; Kant, Melis; Dizdaroglu, Miral; Özerdem, Ayşegül

    2018-05-01

    Oxidatively-induced DNA damage has previously been associated with bipolar disorder. More recently, impairments in DNA repair mechanisms have also been reported. We aimed to investigate oxidatively-induced DNA lesions and expression of DNA glycosylases involved in base excision repair in euthymic patients with bipolar disorder compared to healthy individuals. DNA base lesions including both base and nucleoside modifications were measured using gas chromatography-tandem mass spectrometry and liquid chromatography-tandem mass spectrometry with isotope-dilution in DNA samples isolated from leukocytes of euthymic patients with bipolar disorder (n = 32) and healthy individuals (n = 51). The expression of DNA repair enzymes OGG1 and NEIL1 were measured using quantitative real-time polymerase chain reaction. The levels of malondialdehyde were measured using high performance liquid chromatography. Seven DNA base lesions in DNA of leukocytes of patients and healthy individuals were identified and quantified. Three of them had significantly elevated levels in bipolar patients when compared to healthy individuals. No elevation of lipid peroxidation marker malondialdehyde was observed. The level of OGG1 expression was significantly reduced in bipolar patients compared to healthy individuals, whereas the two groups exhibited similar levels of NEIL1 expression. Our results suggest that oxidatively-induced DNA damage occurs and base excision repair capacity may be decreased in bipolar patients when compared to healthy individuals. Measurement of oxidatively-induced DNA base lesions and the expression of DNA repair enzymes may be of great importance for large scale basic research and clinical studies of bipolar disorder. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Oxide nano particles modified by 2-benzothiazolylthiosuccinic acid

    Dang Quyet Thang; Trinh Anh Truc; Pham Gia Vu; To Thi Xuan Hang

    2015-01-01

    In this study, ZnO nanoparticle was synthesized and modified by a corrosion inhibitor 2-benzothiazolylthiosuccinic acid (BTSA) for corrosion protection of a carbon steel surface. The TEM, SEM and IR analyses were used for characterized the synthesized products. The nano ZnO size in the about 20 nm and the IR analyze shows the presence of BTSA on the ZnO surface. The corrosion inhibition of nano ZnO and nano ZnO bearing BTSA in the NaCL 0.1 M solution was characterized using electrochemical techniques. In the NaCl 0.1 M, both nano ZnO and nano ZnO-BTSA have the inhibition property for carbon steel surface. The inhibition efficiency of ZnO-BTSA in higher than of pure ZnO. The polarization curves indicate that ZnO is anodic inhibitor while the ZnO-BTSA is a mixed-type inhibitor. (author)

  13. Oxide scale formation of modified FeCrAl coatings exposed to liquid lead

    Fetzer, Renate, E-mail: renate.fetzer@kit.edu [Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe (Germany); Weisenburger, Alfons; Jianu, Adrian; Mueller, Georg [Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe (Germany)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Modified FeCrAl coatings show oxide scale formation when exposed to liquid lead. Black-Right-Pointing-Pointer Formation of thin Al-rich oxide scales is promoted by the presence of Y. Black-Right-Pointing-Pointer FeCrAlY with at least 8 wt.% Al forms thin Al-rich oxide scales. Black-Right-Pointing-Pointer For low Al content, thick multilayer Fe-based oxide scales are found. - Abstract: Modified FeCrAl coatings were studied with respect to their capability to form a thin protective oxide scale in liquid lead environment. They were manufactured by low pressure plasma spraying and GESA surface melting, thereby tuning the Al content. The specimens were exposed for 900 h to liquid lead containing 10{sup -6} and 10{sup -8} wt.% oxygen, respectively, at various temperatures from 400 to 550 Degree-Sign C. Threshold values for an Al content that guarantees the formation of thin protective Al-rich oxide scales are determined, dependent on the respective chromium content, on the presence of yttrium in the modified coating, and on the exposure conditions.

  14. Pyrrolizidine alkaloid-derived DNA adducts are common toxicological biomarkers of pyrrolizidine alkaloid N-oxides.

    He, Xiaobo; Xia, Qingsu; Woodling, Kellie; Lin, Ge; Fu, Peter P

    2017-10-01

    There are 660 pyrrolizidine alkaloids (PAs) and PA N-oxides present in the plants, with approximately half being possible carcinogens. We previously reported that a set of four PA-derived DNA adducts is formed in the liver of rats administered a series of hepatocarcinogenic PAs and a PA N-oxide. Based on our findings, we hypothesized that this set of DNA adducts is a common biological biomarker of PA-induced liver tumor formation. In this study, we determined that rat liver microsomal metabolism of five hepatocarcinogenic PAs (lasiocarpine, retrorsine, riddelliine, monocrotaline, and heliotrine) and their corresponding PA N-oxides produced the same set of DNA adducts. Among these compounds, lasiocarpine N-oxide, retrorsine N-oxide, monocrotaline N-oxide, and heliotrine N-oxide are for first time shown to be able to produce these DNA adducts. These results further support the role of these DNA adducts as potential common biomarkers of PA-induced liver tumor initiation. Copyright © 2017. Published by Elsevier B.V.

  15. Pyrrolizidine alkaloid-derived DNA adducts are common toxicological biomarkers of pyrrolizidine alkaloid N-oxides

    Xiaobo He

    2017-10-01

    Full Text Available There are 660 pyrrolizidine alkaloids (PAs and PA N-oxides present in the plants, with approximately half being possible carcinogens. We previously reported that a set of four PA-derived DNA adducts is formed in the liver of rats administered a series of hepatocarcinogenic PAs and a PA N-oxide. Based on our findings, we hypothesized that this set of DNA adducts is a common biological biomarker of PA-induced liver tumor formation. In this study, we determined that rat liver microsomal metabolism of five hepatocarcinogenic PAs (lasiocarpine, retrorsine, riddelliine, monocrotaline, and heliotrine and their corresponding PA N-oxides produced the same set of DNA adducts. Among these compounds, lasiocarpine N-oxide, retrorsine N-oxide, monocrotaline N-oxide, and heliotrine N-oxide are for first time shown to be able to produce these DNA adducts. These results further support the role of these DNA adducts as potential common biomarkers of PA-induced liver tumor initiation.

  16. Comparative study of DNA encapsulation into PLGA microparticles using modified double emulsion methods and spray drying techniques.

    Oster, C G; Kissel, T

    2005-05-01

    Recently, several research groups have shown the potential of microencapsulated DNA as adjuvant for DNA immunization and in tissue engineering approaches. Among techniques generally used for microencapsulation of hydrophilic drug substances into hydrophobic polymers, modified WOW double emulsion method and spray drying of water-in-oil dispersions take a prominent position. The key parameters for optimized microspheres are particle size, encapsulation efficiency, continuous DNA release and stabilization of DNA against enzymatic and mechanical degradation. This study investigates the possibility to encapsulate DNA avoiding shear forces which readily degrade DNA during this microencapsulation. DNA microparticles were prepared with polyethylenimine (PEI) as a complexation agent for DNA. Polycations are capable of stabilizing DNA against enzymatic, as well as mechanical degradation. Further, complexation was hypothesized to facilitate the encapsulation by reducing the size of the macromolecule. This study additionally evaluated the possibility of encapsulating lyophilized DNA and lyophilized DNA/PEI complexes. For this purpose, the spray drying and double emulsion techniques were compared. The size of the microparticles was characterized by laser diffractometry and the particles were visualized by scanning electron microscopy (SEM). DNA encapsulation efficiencies were investigated photometrically after complete hydrolysis of the particles. Finally, the DNA release characteristics from the particles were studied. Particles with a size of <10 microm which represent the threshold for phagocytic uptake could be prepared with these techniques. The encapsulation efficiency ranged from 100-35% for low theoretical DNA loadings. DNA complexation with PEI 25?kDa prior to the encapsulation process reduced the initial burst release of DNA for all techniques used. Spray-dried particles without PEI exhibited high burst releases, whereas double emulsion techniques showed continuous

  17. Modified tricalcium silicate cement formulations with added zirconium oxide.

    Li, Xin; Yoshihara, Kumiko; De Munck, Jan; Cokic, Stevan; Pongprueksa, Pong; Putzeys, Eveline; Pedano, Mariano; Chen, Zhi; Van Landuyt, Kirsten; Van Meerbeek, Bart

    2017-04-01

    This study aims to investigate the effect of modifying tricalcium silicate (TCS) cements on three key properties by adding ZrO 2 . TCS powders were prepared by adding ZrO 2 at six different concentrations. The powders were mixed with 1 M CaCl 2 solution at a 3:1 weight ratio. Biodentine (contains 5 wt.% ZrO 2 ) served as control. To evaluate the potential effect on mechanical properties, the mini-fracture toughness (mini-FT) was measured. Regarding bioactivity, Ca release was assessed using ICP-AES. The component distribution within the cement matrix was evaluated by Feg-SEM/EPMA. Cytotoxicity was assessed using an XTT assay. Adding ZrO 2 to TCS did not alter the mini-FT (p = 0.52), which remained in range of that of Biodentine (p = 0.31). Ca release from TSC cements was slightly lower than that from Biodentine at 1 day (p > 0.05). After 1 week, Ca release from TCS 30 and TCS 50 increased to a level that was significantly higher than that from Biodentine (p  0.05). EPMA revealed a more even distribution of ZrO 2 within the TCS cements. Particles with an un-reacted core were surrounded by a hydration zone. The 24-, 48-, and 72-h extracts of TCS 50 were the least cytotoxic. ZrO 2 can be added to TCS without affecting the mini-FT; Ca release was reduced initially, to reach a prolonged release thereafter; adding ZrO 2 made TCS cements more biocompatible. TCS 50 is a promising cement formulation to serve as a biocompatible hydraulic calcium silicate cement.

  18. Bisphenol a promotes cell survival following oxidative DNA damage in mouse fibroblasts.

    Natalie R Gassman

    Full Text Available Bisphenol A (BPA is a biologically active industrial chemical used in production of consumer products. BPA has become a target of intense public scrutiny following concerns about its association with human diseases such as obesity, diabetes, reproductive disorders, and cancer. Recent studies link BPA with the generation of reactive oxygen species, and base excision repair (BER is responsible for removing oxidatively induced DNA lesions. Yet, the relationship between BPA and BER has yet to be examined. Further, the ubiquitous nature of BPA allows continuous exposure of the human genome concurrent with the normal endogenous and exogenous insults to the genome, and this co-exposure may impact the DNA damage response and repair. To determine the effect of BPA exposure on base excision repair of oxidatively induced DNA damage, cells compromised in double-strand break repair were treated with BPA alone or co-exposed with either potassium bromate (KBrO3 or laser irradiation as oxidative damaging agents. In experiments with KBrO3, co-treatment with BPA partially reversed the KBrO3-induced cytotoxicity observed in these cells, and this was coincident with an increase in guanine base lesions in genomic DNA. The improvement in cell survival and the increase in oxidatively induced DNA base lesions were reminiscent of previous results with alkyl adenine DNA glycosylase-deficient cells, suggesting that BPA may prevent initiation of repair of oxidized base lesions. With laser irradiation-induced DNA damage, treatment with BPA suppressed DNA repair as revealed by several indicators. These results are consistent with the hypothesis that BPA can induce a suppression of oxidized base lesion DNA repair by the base excision repair pathway.

  19. Electrochemical oxidation of ascorbic acid mediated by carbon nano tubes/ Li+/ carbon paste modified solid electrode

    Goh, J.K.; Tan, W.T.

    2008-01-01

    Multi-walled carbon nano tube (MWCNT) was used to modify BPPG electrode because of its unique structure and extraordinary properties. MWCNT modified electrode exhibited obvious enhancing and electro catalyzing effects to the oxidation of ascorbic acid using cyclic voltammetry technique. MWCNT was bonded on BPPG electrode surface using carbon paste with ratio of 30 % (w/ W) carbon paste (binder): 70 % (w/ w) MWCNT. This method of modification has lowered the capacitance background current and enabled lower detection limit of ascorbic acid concentration. The electrical conductivity property of MWCNT modified electrode was further improved with the intercalation with lithium ion and resulted in current enhancement of 2 times on the oxidation current of ascorbic acid. Parameters of pH and temperature showed significant relation to the sensitivity of MWCNT modified electrode. Under the optimized parameters, the calibration curve constructed was linear up from 50 μM to 5 mM with sensitivity of 34.5 mA M -1 . The practical application of MWCNT modified electrode was demonstrated with Vitamin C pill and orange juice. Good reproducibility and recovery of ascorbic acid concentration showed the feasibility of MWCNT modified electrode to be used in the detection of ascorbic acid in aqueous solution. This also proposed MWCNT modified BPPG electrode possessed advantages such as low detection limit, high stability, low cost and simplicity in fabrication. (author)

  20. A Promising Combo Gene Delivery System Developed from (3-Aminopropyl)triethoxysilane-Modified Iron Oxide Nanoparticles and Cationic Polymers

    Zhang, Zubin; Song, Lina; Dong, Jinlai; Guo, Dawei; Du, Xiaolin; Cao, Biyin; Zhang, Yu; Gu, Ning; Mao, Xinliang

    2013-05-01

    (3-Aminopropyl)triethoxysilane-modified iron oxide nanoparticles (APTES-IONPs) have been evaluated for various biomedical applications, including medical imaging and drug delivery. Cationic polymers (CPs) such as Lipofectamine and TurboFect are widely used for research in gene delivery, but their toxicity and low in vivo efficiency limited their further application. In the present study, we synthesized water-soluble APTES-IONPs and developed a combo gene delivery system based on APTES-IONPs and CPs. This system significantly increased gene-binding capacity, protected genes from degradation, and improved gene transfection efficiency for DNA and siRNA in both adherent and suspension cells. Because of its great biocompatibility, high gene-carrying ability, and very low cytotoxicity, this combo gene delivery system will be expected for a wide application, and it might provide a new method for gene therapy.

  1. A Promising Combo Gene Delivery System Developed from (3-Aminopropyl)triethoxysilane-Modified Iron Oxide Nanoparticles and Cationic Polymers

    Zhang Zubin; Song Lina; Dong Jinlai; Guo Dawei; Du Xiaolin; Cao Biyin; Zhang Yu; Gu Ning; Mao Xinliang

    2013-01-01

    (3-Aminopropyl)triethoxysilane-modified iron oxide nanoparticles (APTES-IONPs) have been evaluated for various biomedical applications, including medical imaging and drug delivery. Cationic polymers (CPs) such as Lipofectamine and TurboFect are widely used for research in gene delivery, but their toxicity and low in vivo efficiency limited their further application. In the present study, we synthesized water-soluble APTES-IONPs and developed a combo gene delivery system based on APTES-IONPs and CPs. This system significantly increased gene-binding capacity, protected genes from degradation, and improved gene transfection efficiency for DNA and siRNA in both adherent and suspension cells. Because of its great biocompatibility, high gene-carrying ability, and very low cytotoxicity, this combo gene delivery system will be expected for a wide application, and it might provide a new method for gene therapy.

  2. Oxidative stress generated damage to DNA by gastrointestinal exposure to insoluble particles

    Møller, Peter; Folkmann, J K; Danielsen, P H

    2012-01-01

    that gastrointestinal exposure to single-walled carbon nanotubes (SWCNT), fullerenes C60, carbon black, titanium dioxide and diesel exhaust particles generates oxidized DNA base lesions in organs such as the bone marrow, liver and lung. Oral exposure to nanosized carbon black has also been associated with increased...... level of lipid peroxidation derived exocyclic DNA adducts in the liver, suggesting multiple pathways of oxidative stress for particle-generated damage to DNA. At equal dose, diesel exhaust particles (SRM2975) generated larger levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine in rat liver than carbon black...

  3. Oxidative DNA damage and repair in skeletal muscle of humans exposed to high-altitude hypoxia

    Lundby, Carsten; Pilegaard, Henriette; van Hall, Gerrit

    2003-01-01

    Recent research suggests that high-altitude hypoxia may serve as a model for prolonged oxidative stress in healthy humans. In this study, we investigated the consequences of prolonged high-altitude hypoxia on the basal level of oxidative damage to nuclear DNA in muscle cells, a major oxygen-consuming...

  4. Application of DNA Hybridization Biosensor as a Screening Method for the Detection of Genetically Modified Food Components

    Marian Filipiak

    2008-03-01

    Full Text Available An electrochemical biosensor for the detection of genetically modified food components is presented. The biosensor was based on 21-mer single-stranded oligonucleotide (ssDNA probe specific to either 35S promoter or nos terminator, which are frequently present in transgenic DNA cassettes. ssDNA probe was covalently attached by 5’-phosphate end to amino group of cysteamine self-assembled monolayer (SAM on gold electrode surface with the use of activating reagents – water soluble 1-ethyl-3(3’- dimethylaminopropyl-carbodiimide (EDC and N-hydroxy-sulfosuccinimide (NHS. The hybridization reaction on the electrode surface was detected via methylene blue (MB presenting higher affinity to ssDNA probe than to DNA duplex. The electrode modification procedure was optimized using 19-mer oligoG and oligoC nucleotides. The biosensor enabled distinction between DNA samples isolated from soybean RoundupReady® (RR soybean and non-genetically modified soybean. The frequent introduction of investigated DNA sequences in other genetically modified organisms (GMOs give a broad perspectives for analytical application of the biosensor.

  5. A plasma modified cellulose-chitosan porous membrane allows efficient DNA binding and provides antibacterial properties: A step towards developing a new DNA collecting card.

    Chumwangwapee, Sasiwimon; Chingsungnoen, Artit; Siri, Sineenat

    2016-11-01

    In forensic DNA analyses, biological specimens are collected and stored for subsequent recovery and analysis of DNA. A cost-effective and efficient DNA recovery approach is therefore a need. This study aims to produce a plasma modified cellulose-chitosan membrane (pCE-CS) that efficiently binds and retains DNA as a potential DNA collecting card. The pCE-CS membrane was produced by a phase separation of ionic liquid dissolving CE and CS in water with subsequent surface-modification by a two-step exposure of argon plasma and nitrogen gas. Through plasma modification, the pCE-CS membrane demonstrated better DNA retention after a washing process and higher rate of DNA recovery as compared with the original CE-CS membrane and the commercial FTA card. In addition, the pCE-CS membrane exhibited anti-bacterial properties against both Escherichia coli and Staphylococcus aureus. The results of this work suggest a potential function of the pCE-CS membrane as a DNA collecting card with a high recovery rate of captured DNA. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  6. Sensing characteristics of nanocrystalline bismuth oxide clad-modified fiber optic gas sensor

    Manjula, M.; Karthikeyan, B.; Sastikumar, D.

    2017-08-01

    Gas sensing properties of nanocrystalline bismuth oxide clad - modified fiber optic sensor is reported for ammonia, ethanol, methanol and acetone gasses at room temperature. The output of sensor increases or decreases for certain gasses when the concentration of the gas is increased. The sensor exhibits high response and good selectivity to methanol gas. Time response characteristics of the sensor are also reported.

  7. Identification of total reversible cysteine oxidation in an atherosclerosis model using a modified biotin switch assay.

    Li, Ru; Huang, Jiqing; Kast, Juergen

    2015-05-01

    Oxidative stress due to the imbalance of reactive oxygen species (ROS) and the resulting reversible cysteine oxidation (CysOX) are involved in the early proatherogenic aspect of atherosclerosis. Given that the corresponding redox signaling pathways are still unclear, a modified biotin switch assay was developed to quantify the reversible CysOX in an atherosclerosis model established by using a monocytic cell line treated with platelet releasate. The accumulation of ROS was observed in the model system and validated in human primary monocytes. Through the application of the modified biotin switch assay, we obtained the first reversible CysOX proteome for this model. A total of 75 peptides, corresponding to 53 proteins, were quantified with oxidative modification. The bioinformatics analysis of these CysOX-containing proteins highlighted biological processes including glycolysis, cytoskeleton arrangement, and redox regulation. Moreover, the reversible oxidation of three glycolysis enzymes was observed using this method, and the regulation influence was verified by an enzyme activity assay. NADPH oxidase (NOX) inhibition treatment, in conjunction with the modified biotin switch method, was used to evaluate the global CysOX status. In conclusion, this versatile modified biotin switch assay provides an approach for the quantification of all reversible CysOX and for the study of redox signaling in atherosclerosis as well as in diseases in other biological systems.

  8. Rapid determination of iron oxide content in magnetically modified particulate materials

    Šafařík, Ivo; Nýdlová, L.; Pospíšková, K.; Baldíková, E.; Maděrová, Z.; Šafaříková, Miroslava

    2016-01-01

    Roč. 26, June (2016), s. 114-117 ISSN 1674-2001 Institutional support: RVO:60077344 Keywords : magnetic iron oxide s * magnetic permeability meter * magnetically modified materials Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.621, year: 2016

  9. Effects of a Brussels sprouts extract on oxidative DNA damage and metabolising enzymes in rat liver

    Sørensen, Mette; Jensen, B.R.; Poulsen, Henrik E.

    2001-01-01

    and catalase activity was also assessed in the kidneys. In order to examine a possible effect of the Brussels sprouts related to oxidative stress, we measured oxidative DNA damage in terms of 7-hydro-8-oxo-2'-deoxyguanosine (8-oxodG) and lipid peroxidation in terms of malondialdehyde (MDA) formation...... on MDA levels were found. The present results support the data obtained in several studies that consumption of cruciferous vegetables is capable of inducing various phase II enzyme systems. However, the observed increase in oxidative DNA damage raises the question of whether greatly increased ingestion...

  10. Antioxidant effect of naturally occurring xanthines on the oxidative damage of DNA bases

    Vieira, A.J.S.C.; Telo, J.P.; Pereira, H.F.; Patrocinio, P.F.; Dias, R.M.B.

    1999-01-01

    The repair of the oxidised radicals of adenine and guanosine by several naturally occurring xanthines was studied. Each pair of DNA purine/xanthine was made to react with the sulphate radical and the decrease of the concentration of both compounds was measured by HPLC as a function of irradiation time. The results show that xanthine efficiently prevents the oxidation of the two DNA purines. Theophylline and para-xanthine repair the oxidizes radical of adenine but not the one from guanosine. Theobromine and caffeine to do not show any protecting effect. An order of the oxidation potentials of all the purines studied is proposed. (authors)

  11. Sulfhydryl group content of chicken progesterone receptor: effect of oxidation on DNA binding activity

    Peleg, S.; Schrader, W.T.; O'Malley, B.W.

    1988-01-01

    DNA binding activity of chicken progesterone receptor B form (PRB) and A form (PRA) has been examined. This activity is strongly dependent upon the presence of thiols in the buffer. Stability studies showed that PRB was more sensitive to oxidation that was PRA. Receptor preparations were fractionated by DNA-cellulose chromatography to DNA-positive and DNA-negative subpopulations, and sulfhydryl groups were quantified on immunopurified receptor by labeling with [ 3 H]-N-ethylmaleimide. Labeling of DNA-negative receptors with [ 3 H]-N-ethylmaleimide showed 21-23 sulfhydryl groups on either PRA or PRB form when the proteins were reduced and denatured. A similar number was seen without reduction if denatured DNA-positive receptor species were tested. In contrast, the DNA-negative PRB had only 10-12 sulfhydryl groups detectable without reduction. A similar number (12-13 sulfhydryl groups) was found for PRA species that lost DNA binding activity after exposure to a nonreducing environment in vitro. The authors conclude that the naturally occurring receptor forms unable to bind to DNA, as well as receptor forms that have lost DNA binding activity due to exposure to nonreducing environment in vitro, contain 10-12 oxidized cysteine residues, likely present as disulfide bonds. Since they were unable to reduce the disulfide bonds when the native DNA-negative receptor proteins were treated with dithiothreitol (DTT), they speculate that irreversible loss of DNA binding activity of receptor in vitro is due to oxidation of cysteine residues that are not accessible to DTT in the native state

  12. The detection of HBV DNA with gold-coated iron oxide nanoparticle gene probes

    Xi Dong; Luo Xiaoping; Lu Qianghua; Yao Kailun; Liu Zuli; Ning Qin

    2008-01-01

    Gold-coated iron oxide nanoparticle Hepatitis B virus (HBV) DNA probes were prepared, and their application for HBV DNA measurement was studied. Gold-coated iron oxide nanoparticles were prepared by the citrate reduction of tetra-chloroauric acid in the presence of iron oxide nanoparticles which were added as seeds. With a fluorescence-based method, the maximal surface coverage of hexaethiol 30-mer oligonucleotides and the maximal percentage of hybridization strands on gold-coated iron oxide nanoparticles were (120 ± 8) oligonucleotides per nanoparticle, and (14 ± 2%), respectively, which were comparable with those of (132 ± 10) and (22 ± 3%) in Au nanoparticle groups. Large network aggregates were formed when gold-coated iron oxide nanoparticle HBV DNA gene probe was applied to detect HBV DNA molecules as evidenced by transmission electron microscopy and the high specificity was verified by blot hybridization. Our results further suggested that detecting DNA with iron oxide nanoparticles and magnetic separator was feasible and might be an alternative effective method

  13. Electrocatalytic oxidation of hydrazine at overoxidized polypyrrole film modified glassy carbon electrode

    Majidi, Mir Reza [Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz 51664 (Iran, Islamic Republic of); Jouyban, Abolghasem [Faculty of Pharmacy and Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz 51664 (Iran, Islamic Republic of); Asadpour-Zeynali, Karim [Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz 51664 (Iran, Islamic Republic of)]. E-mail: asadpour@tabrizu.ac.ir

    2007-06-20

    Electrocatalytic oxidation of hydrazine (HZ) was studied on an overoxidized polypyrrole (OPPy) modified glassy carbon electrode using cyclic voltammetry and chronoamperometry techniques. The OPPy-modified glassy carbon electrode has very high catalytic ability for electrooxidation of HZ, which appeared as a reduced overpotential in a wide operational pH range of 5-10. The overall numbers of electrons involved in the catalytic oxidation of HZ, the number of electrons involved in the rate-determining and diffusion coefficient of HZ were estimated using cyclic voltammetry and chronoamperometry. It has been shown that using the OPPy-modified electrode, HZ can be determined by cyclic voltammetry and amperometry with limit of detection 36 and 3.7 {mu}M, respectively. The results of the analysis suggest that the proposed method promises accurate results and could be employed for the routine determination of HZ.

  14. Low-density lipoprotein modified by myeloperoxidase oxidants induces endothelial dysfunction

    Abdo, Adrian; Rayner, B.S.; van Reyk, D.M.

    2017-01-01

    Low-density lipoprotein (LDL) modified by hypochlorous acid (HOCl) produced by myeloperoxidase (MPO) is present in atherosclerotic lesions, where it is implicated in the propagation of inflammation and acceleration of lesion development by multiple pathways, including the induction of endothelial......, although emerging evidence suggests that these particles have distinct biological properties. This is important because elevated plasma SCN- is linked with both the propagation and prevention of atherosclerosis. In this study, we demonstrate that both HOSCN- and HOCl-modified LDL inhibit endothelium......-mediated vasorelaxation ex vivo in rat aortic ring segments. In vitro experiments with human coronary artery endothelial cells show that HOSCN-modified LDL decreases in the production of nitric oxide (NO•) and induces the loss of endothelial nitric oxide synthase (eNOS) activity. This occurs to a similar extent...

  15. Preparation and characterization of sugar cane bagasse fiber modified with nanoparticles of zirconium oxide

    Carvalho, K.C.C. de; Mulinari, D.R.; Voorwald, H.C.J.; Cioffi, M.O.H.

    2010-01-01

    The sugar cane bagasse fiber are renewable materials and have great application potential when used as reinforcement in a polymer matrix to give rise to composite materials and as supports for adsorption of heavy metals. This paper therefore describes the preparation and characterization of bleached and hydrated zirconium oxide modified sugar cane bagasse fiber by conventional precipitation method. Through the technique of electron microscopy we observed the presence of oxide nanoparticles on the fiber surface, proving the efficiency of the conventional precipitation method. With the X-ray diffraction analysis it was determined a decrease of 6.2% in the crystallinity index of modified fibers when compared to the bleached fibers showing the deposition of amorphous zirconium oxide on the fiber surface. (author)

  16. Molecular dynamics simulations of the adsorption of DNA segments onto graphene oxide

    Chen, Junlang; Chen, Shude; Chen, Liang; Wang, Yu

    2014-01-01

    Molecular dynamics simulations were performed to investigate the dynamic process of DNA segments’ adsorption on graphene oxide (GO) in aqueous solution. We find that DNA segments finally ‘stand on’ GO’s surface. Due to energy penalty and electrostatic repulsion, DNA segments cannot lie on the surface of GO with their helical axes parallel to GO’s surface. Both π–π stacking and electrostatic interactions contribute to their binding affinity between the contacting basepair and GO. The results are of great importance to understand the interactions between DNA segments and GO. (paper)

  17. Preterm newborns show slower repair of oxidative damage and paternal smoking associated DNA damage.

    Vande Loock, Kim; Ciardelli, Roberta; Decordier, Ilse; Plas, Gina; Haumont, Dominique; Kirsch-Volders, Micheline

    2012-09-01

    Newborns have to cope with hypoxia during delivery and a sudden increase in oxygen at birth. Oxygen will partly be released as reactive oxygen species having the potential to cause damage to DNA and proteins. In utero, increase of most (non)-enzymatic antioxidants occurs during last weeks of gestation, making preterm neonates probably more sensitive to oxidative stress. Moreover, it has been hypothesized that oxidative stress might be the common etiological factor for certain neonatal diseases in preterm infants. The aim of this study was to assess background DNA damage; in vitro H(2)O(2) induced oxidative DNA damage and repair capacity (residual DNA damage) in peripheral blood mononucleated cells from 25 preterm newborns and their mothers. In addition, demographic data were taken into account and repair capacity of preterm was compared with full-term newborns. Multivariate linear regression analysis revealed that preterm infants from smoking fathers have higher background DNA damage levels than those from non-smoking fathers, emphasizing the risk of paternal smoking behaviour for the progeny. Significantly higher residual DNA damage found after 15-min repair in preterm children compared to their mothers and higher residual DNA damage after 2 h compared to full-term newborns suggest a slower DNA repair capacity in preterm children. In comparison with preterm infants born by caesarean delivery, preterm infants born by vaginal delivery do repair more slowly the in vitro induced oxidative DNA damage. Final impact of passive smoking and of the slower DNA repair activity of preterm infants need to be confirmed in a larger study population combining transgenerational genetic and/or epigenetic effects, antioxidant levels, genotypes, repair enzyme efficiency/levels and infant morbidity.

  18. CLINICAL-EVALUATION OF A MODIFIED ELISA, USING PHOTOBIOTINYLATED DNA, FOR THE DETECTION OF ANTI-DNA ANTIBODIES

    HYLKEMA, MN; HUYGEN, H; KRAMERS, C; VANDERWAL, TJ; DEJONG, J; VANBRUGGEN, MCJ; SWAAK, AJG; BERDEN, JHM; SMEENK, RJT; Hylkema, Machteld

    1994-01-01

    The measurement of anti-dsDNA antibodies is important for the diagnosis and the follow-up of patients with systemic lupus erythematosus (SLE). For routine detection of anti-dsDNA, the Farr assay and the immunofluorescence technique (IFT) on Crithidia luciliae proved to be very useful. The anti-dsDNA

  19. An electrochemical ELISA-like immunosensor for miRNAs detection based on screen-printed gold electrodes modified with reduced graphene oxide and carbon nanotubes.

    Tran, H V; Piro, B; Reisberg, S; Huy Nguyen, L; Dung Nguyen, T; Duc, H T; Pham, M C

    2014-12-15

    We design an electrochemical immunosensor for miRNA detection, based on screen-printed gold electrodes modified with reduced graphene oxide and carbon nanotubes. An original immunological approach is followed, using antibodies directed to DNA.RNA hybrids. An electrochemical ELISA-like amplification strategy was set up using a secondary antibody conjugated to horseradish peroxidase (HRP). Hydroquinone is oxidized into benzoquinone by the HRP/H2O2 catalytic system. In turn, benzoquinone is electroreduced into hydroquinone at the electrode. The catalytic reduction current is related to HRP amount immobilized on the surface, which itself is related to miRNA.DNA surface density on the electrode. This architecture, compared to classical optical detection, lowers the detection limit down to 10 fM. Two miRNAs were studied: miR-141 (a prostate biomarker) and miR-29b-1 (a lung cancer biomarker). Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Hematoxylin multi-wall carbon nanotubes modified glassy carbon electrode for electrocatalytic oxidation of hydrazine

    Zare, Hamid R.; Nasirizadeh, Navid

    2007-01-01

    A new hydrazine sensor has been fabricated by immobilizing hematoxylin at the surface of a glassy carbon electrode (GCE) modified with multi-wall carbon nanotube (MWCNT). The adsorbed thin films of hematoxylin on the MWCNT modified GCE show one pair of peaks with surface confined characteristics. The hematoxylin MWCNT (HMWCNT) modified GCE shows highly catalytic activity toward hydrazine electro-oxidation. The results show that the peak potential of hydrazine at HMWCNT modified GCE surface shifted by about 167 and 255 mV toward negative values compared with that at an MWCNT and activated modified GCE surface, respectively. In addition, at HMWCNT modified electrode surface remarkably improvement the sensitivity of determination of hydrazine. The kinetic parameters, such as the electron transfer coefficient, α, and the standard heterogeneous rate constant, k 0 , for oxidation of hydrazine at the HMWCNT modified GCE were determined and also is shown that the heterogeneous rate constant, k', is strongly potential dependent. The overall number of electron involved in the catalytic oxidation of hydrazine and the number of electrons involved in the rate-determining steps are 2 and 1, respectively. The amperometric detection of hydrazine is carried out at 220 mV in 0.1 M phosphate buffer solution (pH 7) with linear response range 2.0-122.8 μM hydrazine, detection limit of 0.68 μM and sensitivity of 0.0208 μA μM -1 . Finally the amperometric response for hydrazine determination is reproducible, fast and extremely stable, with no loss in sensitivity over a continual 400 s operation

  1. Catalytic oxidation of cyanides in an aqueous phase over individual and manganese-modified cobalt oxide systems

    Christoskova, St.; Stoyanova, M.

    2009-01-01

    The possibility for purification of wastewaters containing free cyanides by applying of a new method based on cyanides catalytic oxidation with air to CO 2 and N 2 at low temperature and atmospheric pressure was investigated. On this purpose, individual and modified with manganese Co-oxide systems as active phase of environmental catalysts were synthesized. The applied method of synthesis favours the preparation of oxide catalytic systems with high active oxygen content (total-O* and surface-O* s ) possessing high mobility, and the metal ions being in a high oxidation state and in an octahedral coordination-factors determining high activity in reactions of complete oxidation. The catalysts employed were characterized by powder X-ray diffraction, Infrared spectroscopy, and chemical analysis. The effect of pH of the medium and catalyst loading on the effectiveness of the cyanide oxidation process, expressed by the degree of conversion (α, %), by the rate constant (k, min -1 ), and COD was studied. The results obtained reveal that using catalysts investigated a high cyanide removal efficiency could be achieved even in strong alkaline medium. The higher activity of the manganese promoted catalytic sample could be explained on the basis of higher total active oxygen content and its higher mobility both depending on the conditions, under which the synthesis of catalyst is being carried out.

  2. Oxidants and not alkylating agents induce rapid mtDNA loss and mitochondrial dysfunction

    Furda, Amy M.; Marrangoni, Adele M.; Lokshin, Anna; Van Houten, Bennett

    2013-01-01

    Mitochondrial DNA (mtDNA) is essential for proper mitochondrial function and encodes 22 tRNAs, 2 rRNAs and 13 polypeptides that make up subunits of complex I, III, IV, in the electron transport chain and complex V, the ATP synthase. Although mitochondrial dysfunction has been implicated in processes such as premature aging, neurodegeneration, and cancer, it has not been shown whether persistent mtDNA damage causes a loss of oxidative phosphorylation. We addressed this question by treating mouse embryonic fibroblasts with either hydrogen peroxide (H2O2) or the alkylating agent methyl methanesulfonate (MMS) and measuring several endpoints, including mtDNA damage and repair rates using QPCR, levels of mitochondrial- and nuclear-encoded proteins using antibody analysis, and a pharmacologic profile of mitochondria using the Seahorse Extracellular Flux Analyzer. We show that a 60 min treatment with H2O2 causes persistent mtDNA lesions, mtDNA loss, decreased levels of a nuclear-encoded mitochondrial subunit, a loss of ATP-linked oxidative phosphorylation and a loss of total reserve capacity. Conversely, a 60 min treatment with 2 mM MMS causes persistent mtDNA lesions but no mtDNA loss, no decrease in levels of a nuclear-encoded mitochondrial subunit, and no mitochondrial dysfunction. These results suggest that persistent mtDNA damage is not sufficient to cause mitochondrial dysfunction. PMID:22766155

  3. Mitochondrial respiratory modifiers confer survival advantage by facilitating DNA repair in cancer cells

    Chauhan, Ankit; Khanna, Suchit; Singh, Saurabh; Rai, Yogesh; Soni, Ravi; Kalra, Namita; Dwarakanath, B.S.; Bhatt, Anant Narayan

    2014-01-01

    High rate of aerobic glycolysis (Warburg effect), one of the primary hallmarks of cancer cells, acquired during the multistep development of tumors is also responsible for therapeutic resistance. Underlying this hallmark is the compromised respiratory metabolism that contributes to the acquisition of the glycolytic phenotype for sustained ATP production and cell proliferation. Nevertheless, the exact mechanisms underlying the glycolysis-linked radio-resistance in cancer cells remain elusive. In this study, we transiently elevated glycolysis by treating human cell lines (HEK293, BMG-1 and OCT-1) with mitochondrial respiratory modifiers (MRMs) viz. 2,4-dinitrophenol, Photosan-3, and Methylene blue to examine if transient stimulation of glycolysis before irradiation using MRMs is sufficient to confer radioresistance. Treatment with MRMs led to a significant (two-fold) increase in glucose consumption and lactate production together with a robust increase in the protein levels of two key regulators of glucose metabolism, i.e. GLUT-1 and HK-II. MRMs also enhanced the clonogenic survival and facilitated DNA repair by activating both non-homologous end joining (NHEJ) and homologous recombination (HR) pathways of DNA double strand break repair leading to reduction in radiation-induced cytogenetic damage (micronuclei formation) in these cells. Inhibition of glucose uptake by inhibitors like 2-deoxy-D-glucose (2-DG), 3-bromo pyruvate (3-BP) and fasentin under conditions of stimulated glycolysis not only reversed the effect but also sensitized the cells to radiation more profoundly. The inhibition of glycolysis using 2-DG also reduced the levels of Ku 70 (NHEJ) and Rad-51 (HR) proteins. Thus, our results suggest that enhanced glycolysis in cancer cells may confer radio-resistance and offers survival advantage partly by enhancing the repair of DNA damage. (author)

  4. Multiplex electrochemical DNA platform for femtomolar-level quantification of genetically modified soybean.

    Manzanares-Palenzuela, C Lorena; de-los-Santos-Álvarez, Noemí; Lobo-Castañón, María Jesús; López-Ruiz, Beatriz

    2015-06-15

    Current EU regulations on the mandatory labeling of genetically modified organisms (GMOs) with a minimum content of 0.9% would benefit from the availability of reliable and rapid methods to detect and quantify DNA sequences specific for GMOs. Different genosensors have been developed to this aim, mainly intended for GMO screening. A remaining challenge, however, is the development of genosensing platforms for GMO quantification, which should be expressed as the number of event-specific DNA sequences per taxon-specific sequences. Here we report a simple and sensitive multiplexed electrochemical approach for the quantification of Roundup-Ready Soybean (RRS). Two DNA sequences, taxon (lectin) and event-specific (RR), are targeted via hybridization onto magnetic beads. Both sequences are simultaneously detected by performing the immobilization, hybridization and labeling steps in a single tube and parallel electrochemical readout. Hybridization is performed in a sandwich format using signaling probes labeled with fluorescein isothiocyanate (FITC) or digoxigenin (Dig), followed by dual enzymatic labeling using Fab fragments of anti-Dig and anti-FITC conjugated to peroxidase or alkaline phosphatase, respectively. Electrochemical measurement of the enzyme activity is finally performed on screen-printed carbon electrodes. The assay gave a linear range of 2-250 pM for both targets, with LOD values of 650 fM (160 amol) and 190 fM (50 amol) for the event-specific and the taxon-specific targets, respectively. Results indicate that the method could be applied for GMO quantification below the European labeling threshold level (0.9%), offering a general approach for the rapid quantification of specific GMO events in foods. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Protection by quercetin and quercetin-rich fruit juice against induction of oxidative DNA damage and formation of BPDE-DNA adducts in human lymphocytes

    Wilms, L.C.; Hollman, P.C.H.; Boots, A.W.; Kleinjans, J.C.S.

    2005-01-01

    Flavonoids are claimed to protect against cardiovascular disease, certain forms of cancer and ageing, possibly by preventing initial DNA damage. Therefore, we investigated the protective effects of the flavonoid quercetin against the formation of oxidative DNA damage and bulky DNA adducts in human

  6. Evaluation of Thermal Oxidative Aging Effect on the Rheological Performance of Modified Asphalt Binders

    Zhu, Cheng

    Modified asphalt binder, which is combined by base binder and additive modifier, has been implemented in pavement industry for more than 30 years. Recently, the oxidative aging mechanism of asphalt binder has been studied for several decades, and appreciable finding results of asphalt binder aging mechanism were achieved from the chemistry and rheological performance aspects. However, most of these studies were conducted with neat binders, the research of aging mechanism of modified asphalt binder was limited. Nowadays, it is still highly necessary to clarify how the asphalt binder aging happens with the modified asphalt binder, what is the effect of the different modifiers (additives) on the binder aging process, how the rheological performance changes under the thermal oxidative aging conditions and so on. The objective of this study was to investigate the effect of isothermal oxidative aging conditions on the rheological performance change of the modified and controlled asphalt binders. There were totally 14 different sorts of asphalt binders had been aged in the PAV pans in the air-force drafted ovens at 50°C, 60°C and 85°C for 0.5 day to 240 days. The Fourier-Transform Infrared Spectroscopy (FT-IR) and Dynamic Shear Rheometer (DSR) were used to perform the experiments. The analysis of rheological indices (Low shear viscosity-LSV, Crossover modulus-G*c, Glover-Rowe Parameter-G-R, DSR function-DSR Fn) as a function of carbonyl area (CA) was conducted. With the SBS modification, both of the hardening susceptibility of the rheological index-LSV and G-R decreases compared with the corresponding base binder. The TR increased the hardening susceptibility of all the rheological indexes. While for the G*c, SBS increases the slope of the most modified asphalt binders except A and B_TR_X series binders. The multiple linear regression statistical analysis results indicate that the oxidative aging conditions play an important role on the CA, and rheological performance

  7. Exploring the origins of the apparent "electrocatalytic" oxidation of kojic acid at graphene modified electrodes.

    Figueiredo-Filho, Luiz C S; Brownson, Dale A C; Fatibello-Filho, Orlando; Banks, Craig E

    2013-08-21

    We explore the recent reports that the use of graphene modified electrodes gives rise to the electrocatalytic oxidation of kojic acid. It is demonstrated that large quantifiable voltammetric signatures are observed on bare/unmodified graphitic electrodes, which are shown to be analytically useful and superior to those observed at graphene modified alternatives. This work is of importance as it shows that control experiments are critical and must be undertaken before "electrocatalysis" is conferred when investigating graphene in electrochemistry. In terms of the electroanalytical response of graphene modified electrodes, a bare edge plane pyrolytic graphite electrode is shown to give rise to an improved linear range and limit of detection, questioning the need to modify electrodes with graphene.

  8. Sensitive detection of cyclophosphamide using DNA-modified carbon paste, pencil graphite and hanging mercury drop electrodes.

    Palaska, P; Aritzoglou, E; Girousi, S

    2007-05-15

    The interaction of cyclophosphamide (CP) with calf thymus double-stranded DNA (dsDNA) and thermally denatured single-stranded DNA (ssDNA) immobilized at the carbon paste (CPE) and pencil graphite electrodes (PGE), was studied electrochemically based on oxidation signals of guanine and adenine using differential pulse voltammetry (DPV). As a result of the interaction of CP with DNA, the voltammetric signals of guanine and adenine increased in the case of dsDNA while a slight increase was observed in ssDNA. The effect of experimental parameters such as the interaction time between CP and DNA forms and the concentration of CP, were studied using DPV with CPE and PGE. Additionally, reproducibility and detection limits were determined using both electrodes. A comparison of the analytical performance between CPE and PGE was done. Our results showed that these two different DNA biosensors could be used for the sensitive, rapid and cost effective detection of CP itself as well as of CP-DNA interaction. Furthermore, the interaction of CP with dsDNA and ssDNA was studied in solution and at the electrode surface by means of alternating current voltammetry (ACV) in 0.3M NaCl and 50mM sodium phosphate buffer (pH 8.5) supporting electrolyte, using a hanging mercury drop electrode (HMDE) as working electrode. The conclusions of this study were mainly based on tensammetric peaks I (at -1.183V) and II (-1.419V) of DNA. This study involved the interaction of CP with surface-confined and solution phase DNA where experimental parameters, such as the concentration of CP and the interaction time, were studied. By increasing the concentration of CP, an increase of peak II was observed in both ds and ssDNA, while an increase of peak I was observed only in the case of dsDNA. An overall conclusion of the study using HMDE was that the interaction of CP with surface-confined DNA significantly differed from that with solution phase DNA. The increase of peaks I and II was lower in the case of

  9. Total oxidant status, total antioxidant capacity and ischemia modified albumin levels in children with celiac disease.

    Sayar, Ersin; Özdem, Sebahat; Uzun, Gülbahar; İşlek, Ali; Yılmaz, Aygen; Artan, Reha

    2015-01-01

    In our study, we aimed to investigate ischemia modified albumin (IMA) as an oxidative stress marker, as well as other oxidant and antioxidant markers that have not been evaluated in children with celiac disease. A total of 37 pediatric patients who were diagnosed with celiac disease (CD) and 29 healthy children were enrolled in this prospective study. We evaluated the IMA, total oxidant status, total antioxidant capacity, sulfhydryl, and advanced oxidation protein products in all of the subjects. We also compared the levels at the time of the diagnosis, and following a gluten-free diet (GFD) in the children with CD. While the IMA and the other oxidant marker levels were significantly higher in the patient group compared to the control group, the antioxidant marker levels were found to be significantly lower in the patient group, compared to the control group. We also determined that the tissue transglutaminase IgA showed a highly positive correlation, and that the IMA showed a moderately positive correlation with the Marsh-Oberhuber histopathological stage. Additionally, the IMA and other oxidant marker levels were significantly lower, while the antioxidant marker levels were significantly higher after the GFD, compared to the pre-diet period. We detected that oxidative stress played a role in the pathogenesis of CD, and that this could be evaluated using oxidative stress markers, which would regress after the GFD. We also detected that IMA is a marker that shows a correlation with the histopathological stage, and may be used in the diagnosis.

  10. NEIL2 protects against oxidative DNA damage induced by sidestream smoke in human cells.

    Altaf H Sarker

    Full Text Available Secondhand smoke (SHS is a confirmed lung carcinogen that introduces thousands of toxic chemicals into the lungs. SHS contains chemicals that have been implicated in causing oxidative DNA damage in the airway epithelium. Although DNA repair is considered a key defensive mechanism against various environmental attacks, such as cigarette smoking, the associations of individual repair enzymes with susceptibility to lung cancer are largely unknown. This study investigated the role of NEIL2, a DNA glycosylase excising oxidative base lesions, in human lung cells treated with sidestream smoke (SSS, the main component of SHS. To do so, we generated NEIL2 knockdown cells using siRNA-technology and exposed them to SSS-laden medium. Representative SSS chemical compounds in the medium were analyzed by mass spectrometry. An increased production of reactive oxygen species (ROS in SSS-exposed cells was detected through the fluorescent detection and the induction of HIF-1α. The long amplicon-quantitative PCR (LA-QPCR assay detected significant dose-dependent increases of oxidative DNA damage in the HPRT gene of cultured human pulmonary fibroblasts (hPF and BEAS-2B epithelial cells exposed to SSS for 24 h. These data suggest that SSS exposure increased oxidative stress, which could contribute to SSS-mediated toxicity. siRNA knockdown of NEIL2 in hPF and HEK 293 cells exposed to SSS for 24 h resulted in significantly more oxidative DNA damage in HPRT and POLB than in cells with control siRNA. Taken together, our data strongly suggest that decreased repair of oxidative DNA base lesions due to an impaired NEIL2 expression in non-smokers exposed to SSS would lead to accumulation of mutations in genomic DNA of lung cells over time, thus contributing to the onset of SSS-induced lung cancer.

  11. Oxidative DNA damage and repair in skeletal muscle of humans exposed to high-altitude hypoxia

    Lundby, Carsten; Pilegaard, Henriette; Hall, Gerrit van; Sander, Mikael; Calbet, Jose; Loft, Steffen; Moeller, Peter

    2003-01-01

    Recent research suggests that high-altitude hypoxia may serve as a model for prolonged oxidative stress in healthy humans. In this study, we investigated the consequences of prolonged high-altitude hypoxia on the basal level of oxidative damage to nuclear DNA in muscle cells, a major oxygen-consuming tissue. Muscle biopsies from seven healthy humans were obtained at sea level and after 2 and 8 weeks of hypoxia at 4100 m.a.s.l. We found increased levels of strand breaks and endonuclease III-sensitive sites after 2 weeks of hypoxia, whereas oxidative DNA damage detected by formamidopyrimidine DNA glycosylase (FPG) protein was unaltered. The expression of 8-oxoguanine DNA glycosylase 1 (OGG1), determined by quantitative RT-PCR of mRNA levels did not significantly change during high-altitude hypoxia, although the data could not exclude a minor upregulation. The expression of heme oxygenase-1 (HO-1) was unaltered by prolonged hypoxia, in accordance with the notion that HO-1 is an acute stress response protein. In conclusion, our data indicate high-altitude hypoxia may serve as a good model for oxidative stress and that antioxidant genes are not upregulated in muscle tissue by prolonged hypoxia despite increased generation of oxidative DNA damage

  12. Electrochemical monitoring of the interaction between mitomycin C and DNA at chitosan--carbon nanotube composite modified electrodes

    CANAVAR, Pembe Ece; EKŞİN, Ece; ERDEM, Arzum

    2015-01-01

    Single-walled carbon nanotube (CNT) and chitosan composite (chitosan*CNT) based sensors were developed as DNA biosensors, and then they were applied for electrochemical investigation of the interaction between the anticancer drug mitomycin C (MC) and DNA. The oxidation signals of MC and guanine were monitored before and after the interaction process by differential pulse voltammetry (DPV). The DPV results were in good agreement with those of electrochemical impedance spectroscopy (EIS)....

  13. Oxidized multi walled carbon nanotubes for improving the electrocatalytic activity of a benzofuran derivative modified electrode

    Mohammad Mazloum-Ardakani

    2016-01-01

    Full Text Available In the present paper, the use of a novel carbon paste electrode modified by 7,8-dihydroxy-3,3,6-trimethyl-3,4-dihydrodibenzo[b,d]furan-1(2H-one (DTD and oxidized multi-walled carbon nanotubes (OCNTs is described for determination of levodopa (LD, acetaminophen (AC and tryptophan (Trp by a simple and rapid method. At first, the electrochemical behavior of DTD is studied, then, the mediated oxidation of LD at the modified electrode is investigated. At the optimum pH of 7.4, the oxidation of LD occurs at a potential about 330 mV less positive than that of an unmodified carbon paste electrode. Based on differential pulse voltammetry (DPV, the oxidation current of LD exhibits a linear range between 1.0 and 2000.0 μM of LD with a detection limit (3σ of 0.36 μM. DPV was also used for simultaneous determination of LD, AC and Trp at the modified electrode. Finally, the proposed electrochemical sensor was used for determinations of these substances in human serum sample.

  14. Bloodcompatibility improvement of titanium oxide film modified by phosphorus ion implantation

    Yang, P.; Leng, Y.X.; Zhao, A.S.; Zhou, H.F.; Xu, L.X.; Hong, S.; Huang, N.

    2006-01-01

    Our recent investigation suggested that Ti-O thin film could be a newly developed antithrombotic material and its thromboresistance could be related to its physical properties of wide gap semiconductor. In this work, titanium oxide film was modified by phosphorus ion implantation and succeeding vacuum annealing. RBS were used to investigate phosphorus distribution profile. Contact angle test results show that phosphorus-doped titanium oxide film becomes more hydrophilic after higher temperature annealing, while its electric conductivity increases. Antithrombotic property of phosphorus-doped titanium oxide thin films was examined by clotting time and platelet adhesion tests. The results suggest that phosphorus doping is an effective way to improve the bloodcompatibility of titanium oxide film, and it is related to the changes of electron structure and surface properties caused by phosphorus doping

  15. Iron carbide on titania surface modified with group VA oxides as Fischer-Tropsch catalysts

    Wachs, I.E.; Fiato, R.A.; Chersich, C.C.

    1986-01-01

    A catalyst is described comprising iron carbide supported on a surface modified titania wherein the support comprises an oxide of a metal selected form the group consisting of niobium, vanadium, tantalum or mixture thereof supported on the titania wherein at least a portion of the supported oxide of niobium, vanandium, tantalum or mixture is in a non-crystalline form. The amount of the supported oxide ranges from about 0.5 to 25 weight percent metal oxide on the titania support based on the total support composition and the catalyst contains at least about 2 milligrams of iron, calculated as Fe/sub 2/O/sub 3/, per square meter of support surface

  16. Transition metal-modified zinc oxides for UV and visible light photocatalysis.

    Bloh, J Z; Dillert, R; Bahnemann, D W

    2012-11-01

    In order to use photocatalysis with solar light, finding more active and especially visible light active photocatalysts is a very important challenge. Also, studies of these photocatalysts should employ a standardized test procedure so that their results can be accurately compared and evaluated with one another. A systematic study of transition metal-modified zinc oxide was conducted to determine whether they are suitable as visible light photocatalysts. The photocatalytic activity of ZnO modified with eight different transition metals (Cu, Co, Fe, Mn, Ni, Ru, Ti, Zr) in three different concentrations (0.01, 0.1, and 1 at.%) was investigated under irradiation with UV as well as with visible light. The employed activity test is the gas-phase degradation of acetaldehyde as described by the ISO standard 22197-2. The results suggest that the UV activity can be improved with almost any modification element and that there exists an optimal modification ratio at about 0.1 at.%. Additionally, Mn- and Ru-modified ZnO display visible light activity. Especially the Ru-modified ZnO is highly active and surpasses the visible light activity of all studied titania standards. These findings suggest that modified zinc oxides may be a viable alternative to titanium dioxide-based catalysts for visible light photocatalysis. Eventually, possible underlying mechanisms are proposed and discussed.

  17. Effect of chemical heterogeneity on photoluminescence of graphite oxide treated with S-/N-containing modifiers

    Ebrahim, Amani M.; Rodríguez-Castellón, Enrique; Montenegro, José María; Bandosz, Teresa J.

    2015-03-01

    Graphite oxide (GO) obtained using Hummers method was modified by hydrothermal treatment either with sulfanilic acid or polystyrene (3-ammonium) sulfonate at 100 °C or 85 °C, respectively. Both modifiers contain sulfur in the oxidized forms and nitrogen in the reduced forms. The materials were characterized using FTIR, XPS, thermal analysis, potentiometric titration and SEM. Their photoluminescent properties and their alteration with an addition of Ag+ were also measured. As a result of these modifications nitrogen was introduced to the graphene layers as amines, imides, amides, and sulfur as sulfones and sulfonic acids. Moreover, the presence of polyaniline was detected. This significantly affected the polarity, acid-base character, and conductivity of the materials. Apparently carboxylic groups of GO were involved in the surface reactions. The modified GOs lost their layered structure and the modifications resulted in the high degree of structural and chemical heterogeneity. Photoluminescence in visible light was recorded and linked to the presence of heteroatoms. For the polystyrene (3-ammonium) sulfonate modified sample addition of Ag+ quenched the photoluminescence at low wavelength showing sensitivity as a possible optical detector. No apparent effect was found for the sulfanilic acid modified sample.

  18. Synthesis, characterisation and electrochemical evaluation of reduced graphene oxide modified antimony nanoparticles

    Silwana, Bongiwe; Horst, Charlton van der [Natural Resources and the Environment (NRE), Council for Scientific and Industrial Research (CSIR), Stellenbosch 7600 (South Africa); SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535 (South Africa); Iwuoha, Emmanuel [SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535 (South Africa); Somerset, Vernon, E-mail: vsomerset@csir.co.za [Natural Resources and the Environment (NRE), Council for Scientific and Industrial Research (CSIR), Stellenbosch 7600 (South Africa)

    2015-10-01

    This paper demonstrates some aspects on the synthesis and characterisation of nanoparticles of metallic alloys using polyvinyl alcohol as a stabiliser, which combines high surface area and superior hybrid properties. The present experimental design was to synthesise a nanocomposite of reduced graphene oxide and antimony nanoparticles to be used as thin films for macro- and micro-carbon electrodes for enhancing sensing of different toxic metal pollutants in the environment. The synthetic process of reduced graphene oxide was done using the modified Hummers method while antimony pentachloride was reduced with sodium borohydride into nanoparticles of antimony using polyvinyl-alcohol as a stabiliser. The systematic investigation of morphology was done by scanning electron microscopy and high resolution-transmission electron microscope, which revealed the synthesis of a product, consists of reduced graphene oxide antimony nanoparticles. The electrochemical behaviour of the reduced graphene oxide antimony nanoparticles coated on a glassy carbon electrode was performed using voltammetric and impedance techniques. Electrochemical impedance measurements showed that the overall resistance, including the charge–transfer resistance, was smaller with reduced graphene oxide antimony nanoparticles than reduced graphene oxide and antimony nanoparticles, on their own. Evaluation of the reduced graphene oxide antimony nanoparticle sensor in the stripping voltammetry has shown a linear working range for concentration of platinum (II) between 6.0 × 10{sup −6}–5.4 × 10{sup −5} μg L{sup −1} with limit of detection of 6 × 10{sup −6} μg L{sup −1} (signal-to-noise ratio = 3), which is below the World Health Organisation guidelines for freshwater. - Highlights: • Reduced graphene oxide modified antimony nanoparticles were chemically synthesised. • TEM results show rGO-Sb nanoparticles with a diameter range of between 2 and 20 nm. • Impedance results confirm

  19. Oxidative DNA damage and its repair in rat spleen following subchronic exposure to aniline

    Ma Huaxian; Wang Jianling; Abdel-Rahman, Sherif Z.; Boor, Paul J.; Khan, M. Firoze

    2008-01-01

    The mechanisms by which aniline exposure elicits splenotoxic response, especially the tumorigenic response, are not well-understood. Splenotoxicity of aniline is associated with iron overload and generation of reactive oxygen species (ROS) which can cause oxidative damage to DNA, proteins and lipids (oxidative stress). 8-Hydroxy-2'-deoxyguanosine (8-OHdG) is one of the most abundant oxidative DNA lesions resulting from ROS, and 8-oxoguanine glycosylase 1 (OGG1), a specific DNA glycosylase/lyase enzyme, plays a key role in the removal of 8-OHdG adducts. This study focused on examining DNA damage (8-OHdG) and repair (OGG1) in the spleen in an experimental condition preceding a tumorigenic response. To achieve that, male Sprague-Dawley rats were subchronically exposed to aniline (0.5 mmol/kg/day via drinking water for 30 days), while controls received drinking water only. Aniline treatment led to a significant increase in splenic oxidative DNA damage, manifested as a 2.8-fold increase in 8-OHdG levels. DNA repair activity, measured as OGG1 base excision repair (BER) activity, increased by ∼ 1.3 fold in the nuclear protein extracts (NE) and ∼ 1.2 fold in the mitochondrial protein extracts (ME) of spleens from aniline-treated rats as compared to the controls. Real-time PCR analysis for OGG1 mRNA expression in the spleen revealed a 2-fold increase in expression in aniline-treated rats than the controls. Likewise, OGG1 protein expression in the NEs of spleens from aniline-treated rats was ∼ 1.5 fold higher, whereas in the MEs it was ∼ 1.3 fold higher than the controls. Aniline treatment also led to stronger immunostaining for both 8-OHdG and OGG1 in the spleens, confined to the red pulp areas. It is thus evident from our studies that aniline-induced oxidative stress is associated with increased oxidative DNA damage. The BER pathway was also activated, but not enough to prevent the accumulation of oxidative DNA damage (8-OHdG). Accumulation of mutagenic oxidative

  20. Identification of DNA polymerase molecules repairing DNA irradiated damage and molecular biological study on modified factors of mutation rate

    Yamada, Koichi; Inoue, Shuji [National Inst. of Healthand Nutrition, Tokyo (Japan)

    1999-02-01

    DNA repairing polymerase has not been identified in human culture cells because the specificities of enzyme inhibitors used in previous studies were not so high. In this study, anti-sense oligonucleotides were transfected into human fibroblast cells by electroporation and several clones selected by geneticin treatment were found to express the RNA of the incorporated DNA. However, the expression was not significant and its reproducibility was poor. Then, a study on repairing mechanism was made using XP30 RO and XP 115 LO cells which are variant cells of xeroderma pigmentosum, a human hereditary disease aiming to identify the DNA polymerase related to the disease. There were abnormalities in DNA polymerase subunit {delta} or {epsilon} which consists DNA replication complex. Thus, it was suggested that the DNA replication of these mutant cells might terminate at the site containing such abnormality. (M.N.)

  1. Cyclic etching of tin-doped indium oxide using hydrogen-induced modified layer

    Hirata, Akiko; Fukasawa, Masanaga; Nagahata, Kazunori; Li, Hu; Karahashi, Kazuhiro; Hamaguchi, Satoshi; Tatsumi, Tetsuya

    2018-06-01

    The rate of etching of tin-doped indium oxide (ITO) and the effects of a hydrogen-induced modified layer on cyclic, multistep thin-layer etching were investigated. It was found that ITO cyclic etching is possible by precisely controlling the hydrogen-induced modified layer. Highly selective etching of ITO/SiO2 was also investigated, and it was suggested that cyclic etching by selective surface adsorption of Si can precisely control the etch rates of ITO and SiO2, resulting in an almost infinite selectivity for ITO over SiO2 and in improved profile controllability.

  2. Covalently bound DNA on naked iron oxide nanoparticles: Intelligent colloidal nano-vector for cell transfection.

    Magro, Massimiliano; Martinello, Tiziana; Bonaiuto, Emanuela; Gomiero, Chiara; Baratella, Davide; Zoppellaro, Giorgio; Cozza, Giorgio; Patruno, Marco; Zboril, Radek; Vianello, Fabio

    2017-11-01

    Conversely to common coated iron oxide nanoparticles, novel naked surface active maghemite nanoparticles (SAMNs) can covalently bind DNA. Plasmid (pDNA) harboring the coding gene for GFP was directly chemisorbed onto SAMNs, leading to a novel DNA nanovector (SAMN@pDNA). The spontaneous internalization of SAMN@pDNA into cells was compared with an extensively studied fluorescent SAMN derivative (SAMN@RITC). Moreover, the transfection efficiency of SAMN@pDNA was evaluated and explained by computational model. SAMN@pDNA was prepared and characterized by spectroscopic and computational methods, and molecular dynamic simulation. The size and hydrodynamic properties of SAMN@pDNA and SAMN@RITC were studied by electron transmission microscopy, light scattering and zeta-potential. The two nanomaterials were tested by confocal scanning microscopy on equine peripheral blood-derived mesenchymal stem cells (ePB-MSCs) and GFP expression by SAMN@pDNA was determined. Nanomaterials characterized by similar hydrodynamic properties were successfully internalized and stored into mesenchymal stem cells. Transfection by SAMN@pDNA occurred and GFP expression was higher than lipofectamine procedure, even in the absence of an external magnetic field. A computational model clarified that transfection efficiency can be ascribed to DNA availability inside cells. Direct covalent binding of DNA on naked magnetic nanoparticles led to an extremely robust gene delivery tool. Hydrodynamic and chemical-physical properties of SAMN@pDNA were responsible of the successful uptake by cells and of the efficiency of GFP gene transfection. SAMNs are characterized by colloidal stability, excellent cell uptake, persistence in the host cells, low toxicity and are proposed as novel intelligent DNA nanovectors for efficient cell transfection. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Oxidative damage to DNA and lipids as biomarkers of exposure to air pollution

    Møller, Peter; Loft, Steffen

    2010-01-01

    BACKGROUND: Air pollution is thought to exert health effects through oxidative stress, which causes damage to DNA and lipids. OBJECTIVE: We determined whether levels of oxidatively damaged DNA and lipid peroxidation products in cells or bodily fluids from humans are useful biomarkers...... of biologically effective dose in studies of the health effects of exposure to particulate matter (PM) from combustion processes. DATA SOURCES: We identified publications that reported estimated associations between environmental exposure to PM and oxidative damage to DNA and lipids in PubMed and EMBASE. We also...... identified publications from reference lists and articles cited in the Web of Science. DATA EXTRACTION: For each study, we obtained information on the estimated effect size to calculate the standardized mean difference (unitless) and determined the potential for errors in exposure assessment and analysis...

  4. Age and metabolic risk factors associated with oxidatively damaged DNA in human peripheral blood mononuclear cells

    Løhr, Mille; Jensen, Annie; Eriksen, Louise

    2015-01-01

    Aging is associated with oxidative stress-generated damage to DNA and this could be related to metabolic disturbances. This study investigated the association between levels of oxidatively damaged DNA in peripheral blood mononuclear cells (PBMCs) and metabolic risk factors in 1,019 subjects, aged...... 18-93 years. DNA damage was analyzed as strand breaks by the comet assay and levels of formamidopyrimidine (FPG-) and human 8-oxoguanine DNA glycosylase 1 (hOGG1)-sensitive sites There was an association between age and levels of FPG-sensitive sites for women, but not for men. The same tendency......, cholesterol and glycosylated hemoglobin (HbA1c). In the group of men, there were significant positive associations between alcohol intake, HbA1c and FPG-sensitive sites in multivariate analysis. The levels of metabolic risk factors were positively associated with age, yet only few subjects fulfilled all...

  5. Fish DNA-modified clays: Towards highly flame retardant polymer nanocomposite with improved interfacial and mechanical performance

    Zabihi, Omid; Ahmadi, Mojtaba; Khayyam, Hamid; Naebe, Minoo

    2016-12-01

    Deoxyribonucleic Acid (DNA) has been recently found to be an efficient renewable and environmentally-friendly flame retardant. In this work, for the first time, we have used waste DNA from fishing industry to modify clay structure in order to increase the clay interactions with epoxy resin and take benefit of its additional thermal property effect on thermo-physical properties of epoxy-clay nanocomposites. Intercalation of DNA within the clay layers was accomplished in a one-step approach confirmed by FT-IR, XPS, TGA, and XRD analyses, indicating that d-space of clay layers was expanded from ~1.2 nm for pristine clay to ~1.9 nm for clay modified with DNA (d-clay). Compared to epoxy nanocomposite containing 2.5%wt of Nanomer I.28E organoclay (m-clay), it was found that at 2.5%wt d-clay loading, significant enhancements of ~14%, ~6% and ~26% in tensile strength, tensile modulus, and fracture toughness of epoxy nanocomposite can be achieved, respectively. Effect of DNA as clay modifier on thermal performance of epoxy nanocomposite containing 2.5%wt d-clay was evaluated using TGA and cone calorimetry analysis, revealing significant decreases of ~4000 kJ/m2 and ~78 kW/m2 in total heat release and peak of heat release rate, respectively, in comparison to that containing 2.5%wt of m-clay.

  6. Iron modified titanium–hafnium binary oxides as catalysts in total oxidation of ethyl acetate

    Tsoncheva, T.; Ivanova, R.; Henych, Jiří; Velinov, N.; Kormunda, M.; Dimitrov, M.; Paneva, D.; Slušná, Michaela; Mitov, I.; Štengl, Václav

    2016-01-01

    Roč. 81, JUN (2016), s. 14-19 ISSN 1566-7367 R&D Projects: GA MŠk LM2015073 Institutional support: RVO:61388980 Keywords : Titania–hafnia binary oxide s * Iron modifications * Support effect * Ethyl acetate oxydation Subject RIV: CA - Inorganic Chemistry Impact factor: 3.330, year: 2016

  7. Assessment of evidence for nanosized titanium dioxide-generated DNA strand breaks and oxidatively damaged DNA in cells and animal models

    Møller, Peter; Jensen, Ditte Marie; Wils, Regitze Sølling

    2017-01-01

    Nanosized titanium dioxide (TiO2) has been investigated in numerous studies on genotoxicity, including comet assay endpoints and oxidatively damaged DNA in cell cultures and animal models. The results have been surprisingly mixed, which might be attributed to physico-chemical differences...... culture studies also demonstrate increased levels of oxidatively damaged DNA after exposure to TiO2. There are relatively few studies on animal models where DNA strand breaks and oxidatively damaged DNA have been tested with reliable methods. Collectively, this review shows that exposure to nanosized TiO2...... of the tested TiO2. In the present review, we assess the role of certain methodological issues and publication bias. The analysis shows that studies on DNA strand breaks without proper assay controls or very low intra-group variation tend to show statistically significant effects. Levels of oxidatively damaged...

  8. Polyacrylamide grafting of modified graphene oxides by in situ free radical polymerization

    Tang, Mingyi; Xu, Xiaoyang; Wu, Tao; Zhang, Sai; Li, Xianxian; Li, Yi

    2014-01-01

    Highlights: • Graphene oxide (GO) was modified by chemical reactions to functionalized GO (FGO). • The FGOs and the GO were then subjected to in situ free radical polymerization. • Hydroxyl groups of GO were the most reactive grafting sites. - Abstract: Graphene oxide (GO) was modified using chemical reactions to obtain three types of functionalized GO sheets (FGO). The FGO sheets and the GO were then subjected to in situ free radical polymerization in order to study the grafting polymerization. The FGO and grafted-.FGO were analyzed with Fourier transform infrared spectroscopy, scanning electronic microscopy, thermo-gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The grafting percentages in the materials were calculated using the TGA and XPS results. The FGO sheets with different functional groups exhibited different grafting abilities, and hydroxyl groups were proven to be the most reactive grafting sites for the in situ free radical grafting polymerization of polyacrylamide

  9. Enhanced specific capacitance of modified needle cokes by controlling oxidation treatment

    Yang, Sunhye; Kim, Ick-Jun; Choi, In-Sik; Soo Kim, Hyun; Tack Kim, Yu

    2010-01-01

    The electric double-layer performance of needle cokes can be affected by the morphology of structures. Hence, we introduce modified needle cokes by using simple oxidation treatment. The degree of graphitization with high specific capacitance is controlled by acid and heat treatment. The active sites of cokes are increased with increasing oxidation time. Dilute nitric acid (HNO 3 ) and sodium chlorate (NaClO 3 ) are used for the activation of cokes. In this case, the interlayer distance is dramatically increased from 3.5 to 8.9 A. The specific capacitances are 33 F g -1 and 30 F ml -1 , respectively, on a two-electrode system with a potential range of 0-2.5 V. The behaviors of double-layer capacitance are demonstrated by the charge-discharge process and the morphologies of modified needle cokes are analyzed by XRD, FE-SEM, BET and elemental analysis.

  10. Polyacrylamide grafting of modified graphene oxides by in situ free radical polymerization

    Tang, Mingyi [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Xu, Xiaoyang, E-mail: xiaoyangxu2012@163.com [School of Science, Tianjin University, Tianjin 30072 (China); Wu, Tao [School of Science, Tianjin University, Tianjin 30072 (China); Zhang, Sai; Li, Xianxian [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Li, Yi, E-mail: liyi@tju.edu.cn [School of Science, Tianjin University, Tianjin 30072 (China)

    2014-12-15

    Highlights: • Graphene oxide (GO) was modified by chemical reactions to functionalized GO (FGO). • The FGOs and the GO were then subjected to in situ free radical polymerization. • Hydroxyl groups of GO were the most reactive grafting sites. - Abstract: Graphene oxide (GO) was modified using chemical reactions to obtain three types of functionalized GO sheets (FGO). The FGO sheets and the GO were then subjected to in situ free radical polymerization in order to study the grafting polymerization. The FGO and grafted-.FGO were analyzed with Fourier transform infrared spectroscopy, scanning electronic microscopy, thermo-gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The grafting percentages in the materials were calculated using the TGA and XPS results. The FGO sheets with different functional groups exhibited different grafting abilities, and hydroxyl groups were proven to be the most reactive grafting sites for the in situ free radical grafting polymerization of polyacrylamide.

  11. Evidence that OGG1 glycosylase protects neurons against oxidative DNA damage and cell death under ischemic conditions

    Liu, Dong; Croteau, Deborah L; Souza-Pinto, Nadja

    2011-01-01

    to ischemic and oxidative stress. After exposure of cultured neurons to oxidative and metabolic stress levels of OGG1 in the nucleus were elevated and mitochondria exhibited fragmentation and increased levels of the mitochondrial fission protein dynamin-related protein 1 (Drp1) and reduced membrane potential......7,8-Dihydro-8-oxoguanine DNA glycosylase (OGG1) is a major DNA glycosylase involved in base-excision repair (BER) of oxidative DNA damage to nuclear and mitochondrial DNA (mtDNA). We used OGG1-deficient (OGG1(-/-)) mice to examine the possible roles of OGG1 in the vulnerability of neurons....... Cortical neurons isolated from OGG1(-/-) mice were more vulnerable to oxidative insults than were OGG1(+/+) neurons, and OGG1(-/-) mice developed larger cortical infarcts and behavioral deficits after permanent middle cerebral artery occlusion compared with OGG1(+/+) mice. Accumulations of oxidative DNA...

  12. Salivary DNA and markers of oxidative stress in patients with chronic periodontitis.

    Baňasová, Lenka; Kamodyová, Natália; Janšáková, Katarína; Tóthová, Ľubomíra; Stanko, Peter; Turňa, Ján; Celec, Peter

    2015-03-01

    Previous observational studies have shown that periodontal status is associated with salivary markers of oxidative damage. A direct comparison of periodontitis patients and controls using a wide palette of salivary markers of oxidative stress is lacking. Characteristics of salivary DNA in periodontitis are unknown. The aim of this study was to compare the salivary markers of oxidative stress and characteristics of salivary DNA between patients with chronic periodontitis and periodontitis-free controls. Saliva was collected from 23 patients with chronic periodontitis and 19 periodontitis-free controls. All participants underwent a clinical periodontal examination. Markers of oxidative and carbonyl stress were measured in saliva. Human and bacterial DNA was quantified, and human DNA integrity was assessed. Salivary thiobarbituric acid-reacting substances were higher in patients than in controls; at least in men, the difference was significant (p periodontitis patients. The results confirmed the association of salivary thiobarbituric acid-reacting substances with periodontitis. Lipid peroxidation in periodontitis seems to be caused by increased production of reactive oxygen species in men and by decreased antioxidant status in women. Whether lower salivary DNA integrity is involved in the pathogenesis of periodontitis remains to be elucidated. Salivary thiobarbituric acid-reacting substances are associated with periodontitis at least on a population level. Sex-specific causes of lipid peroxidation might point towards different pathogenic mechanisms.

  13. Immunohistochemical analysis of oxidative stress and DNA repair proteins in normal mammary and breast cancer tissues

    Curtis, Carol D; Thorngren, Daniel L; Nardulli, Ann M

    2010-01-01

    During the course of normal cellular metabolism, oxygen is consumed and reactive oxygen species (ROS) are produced. If not effectively dissipated, ROS can accumulate and damage resident proteins, lipids, and DNA. Enzymes involved in redox regulation and DNA repair dissipate ROS and repair the resulting damage in order to preserve a functional cellular environment. Because increased ROS accumulation and/or unrepaired DNA damage can lead to initiation and progression of cancer and we had identified a number of oxidative stress and DNA repair proteins that influence estrogen responsiveness of MCF-7 breast cancer cells, it seemed possible that these proteins might be differentially expressed in normal mammary tissue, benign hyperplasia (BH), ductal carcinoma in situ (DCIS) and invasive breast cancer (IBC). Immunohistochemistry was used to examine the expression of a number of oxidative stress proteins, DNA repair proteins, and damage markers in 60 human mammary tissues which were classified as BH, DCIS or IBC. The relative mean intensity was determined for each tissue section and ANOVA was used to detect statistical differences in the relative expression of BH, DCIS and IBC compared to normal mammary tissue. We found that a number of these proteins were overexpressed and that the cellular localization was altered in human breast cancer tissue. Our studies suggest that oxidative stress and DNA repair proteins not only protect normal cells from the damaging effects of ROS, but may also promote survival of mammary tumor cells

  14. Schizophrenia and oxidative stress: glutamate cysteine ligase modifier as a susceptibility gene

    Tosic, Mirjana; Ott, Jurg; Barral, Sandra

    2006-01-01

    Oxidative stress could be involved in the pathophysiology of schizophrenia, a major psychiatric disorder. Glutathione (GSH), a redox regulator, is decreased in patients' cerebrospinal fluid and prefrontal cortex. The gene of the key GSH-synthesizing enzyme, glutamate cysteine ligase modifier (GCLM......) subunit, is strongly associated with schizophrenia in two case-control studies and in one family study. GCLM gene expression is decreased in patients' fibroblasts. Thus, GSH metabolism dysfunction is proposed as one of the vulnerability factors for schizophrenia....

  15. Schizophrenia and oxidative stress: glutamate cysteine ligase modifier as a susceptibility gene

    Tosic, Mirjana; Ott, Jurg; Barral, Sandra

    2006-01-01

    Oxidative stress could be involved in the pathophysiology of schizophrenia, a major psychiatric disorder. Glutathione (GSH), a redox regulator, is decreased in patients' cerebrospinal fluid and prefrontal cortex. The gene of the key GSH-synthesizing enzyme, glutamate cysteine ligase modifier (GCL......) subunit, is strongly associated with schizophrenia in two case-control studies and in one family study. GCLM gene expression is decreased in patients' fibroblasts. Thus, GSH metabolism dysfunction is proposed as one of the vulnerability factors for schizophrenia....

  16. Body iron is a contributor to oxidative damage of DNA

    Tuomainen, T.P.; Loft, Steffen Huitfeldt; Nyyssonen, K.

    2007-01-01

    The transition metal iron is catalytically highly active in vitro, and not surprisingly, body iron has been suggested to promote oxidative stress in vivo. In the current analysis we studied the association of serum ferritin concentration and serum soluble transferrin receptor concentration...... with daily urinary 8-hydroxydeoxyguanosine excretion, a marker of oxidative stress, in 48 mildly dyslipidemic men in East Finland. In multivariate linear regression analyses allowing for age, smoking, body mass index and physical exercise, serum ferritin concentration predicted the excretion rate at B = 0.......17 (95% CI 0.08-0.26, P = 0.001), and serum soluble transferrin receptor to ferritin concentration ratio (TfR/ferritin) predicted the excretion rate at B = - 0.13 (95% CI - 0.21 to - 0.05, P = 0.002). Our data suggest that body iron contributes to excess oxidative stress already at non-iron overload...

  17. Nickel exposure induces oxidative damage to mitochondrial DNA in Neuro2a cells: the neuroprotective roles of melatonin.

    Xu, Shang-Cheng; He, Min-Di; Lu, Yong-Hui; Li, Li; Zhong, Min; Zhang, Yan-Wen; Wang, Yuan; Yu, Zheng-Ping; Zhou, Zhou

    2011-11-01

    Recent studies suggest that oxidative stress and mitochondrial dysfunction play important roles in the neurotoxicity of nickel. Because mitochondrial DNA (mtDNA) is highly vulnerable to oxidative stress and melatonin can efficiently protect mtDNA against oxidative damage in various pathological conditions, the aims of this study were to determine whether mtDNA oxidative damage was involved in the neurotoxicity of nickel and to assay the neuroprotective effects of melatonin in mtDNA. In this study, we exposed mouse neuroblastoma cell lines (Neuro2a) to different concentrations of nickel chloride (NiCl(2), 0.125, 0.25, and 0.5 mm) for 24 hr. We found that nickel significantly increased reactive oxygen species (ROS) production and mitochondrial superoxide levels. In addition, nickel exposure increased mitochondrial 8-hydroxyguanine (8-OHdG) content and reduced mtDNA content and mtDNA transcript levels. Consistent with this finding, nickel was found to destroy mtDNA nucleoid structure and decrease protein levels of Tfam, a key protein component for nucleoid organization. However, all the oxidative damage to mtDNA induced by nickel was efficiently attenuated by melatonin pretreatment. Our results suggest that oxidative damage to mtDNA may account for the neurotoxicity of nickel. Melatonin has great pharmacological potential in protecting mtDNA against the adverse effects of nickel in the nervous system. © 2011 John Wiley & Sons A/S.

  18. Time course evaluation of N-nitrosodialkylamines-induced DNA alkylation and oxidation in liver of mosquito fish

    Chao, M.-R.; Chang, Y.-Z.; Wong, R.-H.; Hu, C.-W.

    2009-01-01

    Here we simultaneously measured N7-alkylguanines and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in liver of small fish, respectively, to assess the time course of the formation and removal of alkylation and oxidative damage to DNA caused by N-nitrosodialkylamines. Mosquito fish (Gambusia affinis) were killed at various times during (4 days) and post-exposure (16 days) to N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) alone or their combination with concentrations of 10 and 50 mg/l. The modified guanine adducts were sensitively and selectively quantitated by isotope-dilution LC-MS/MS methods. During exposure, N7-methylguanine (N7-MeG) and N7-ethylguanine (N7-EtG) in liver DNA increased with the duration and dose of N-nitrosodialkylamine exposure, while 8-oxodG was dose-dependently induced within 1 day. It was found that NDMA formed substantially more N7-alkylated guanines and 8-oxodG than NDEA on the basis of adducts formed per micromolar concentration, suggesting that NDMA can be more easily bioactivated than NDEA to form reactive alkylating agents with the concomitant formation of oxygen radicals. After cessation of exposure, N7-alkylguanines remained elevated for 1 day and then gradually decreased over time but still higher than the background levels, even at day 16 (half-lives of 7-8 days). However, 8-oxodG was excised quickly from liver DNA and returned to the background level within 4 days post-exposure (half-lives less than 2 days). Taken together, this study firstly demonstrated that in addition to alkylation, N-nitrosodialkylamines can concurrently cause oxidative damage to DNA in vivo

  19. Time course evaluation of N-nitrosodialkylamines-induced DNA alkylation and oxidation in liver of mosquito fish

    Chao, M -R [Department of Occupational Safety and Health, Chung Shan Medical University, Taichung 402, Taiwan (China); Institute of Medical and Molecular Toxicology, Chung Shan Medical University, Taichung 402, Taiwan (China); Chang, Y -Z [Institute of Medical and Molecular Toxicology, Chung Shan Medical University, Taichung 402, Taiwan (China); Wong, R -H [Department of Public Health, Chung Shan Medical University, Taichung 402, Taiwan (China); Hu, C.-W. [Department of Public Health, Chung Shan Medical University, Taichung 402, Taiwan (China)], E-mail: windyhu@csmu.edu.tw

    2009-01-15

    Here we simultaneously measured N7-alkylguanines and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in liver of small fish, respectively, to assess the time course of the formation and removal of alkylation and oxidative damage to DNA caused by N-nitrosodialkylamines. Mosquito fish (Gambusia affinis) were killed at various times during (4 days) and post-exposure (16 days) to N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) alone or their combination with concentrations of 10 and 50 mg/l. The modified guanine adducts were sensitively and selectively quantitated by isotope-dilution LC-MS/MS methods. During exposure, N7-methylguanine (N7-MeG) and N7-ethylguanine (N7-EtG) in liver DNA increased with the duration and dose of N-nitrosodialkylamine exposure, while 8-oxodG was dose-dependently induced within 1 day. It was found that NDMA formed substantially more N7-alkylated guanines and 8-oxodG than NDEA on the basis of adducts formed per micromolar concentration, suggesting that NDMA can be more easily bioactivated than NDEA to form reactive alkylating agents with the concomitant formation of oxygen radicals. After cessation of exposure, N7-alkylguanines remained elevated for 1 day and then gradually decreased over time but still higher than the background levels, even at day 16 (half-lives of 7-8 days). However, 8-oxodG was excised quickly from liver DNA and returned to the background level within 4 days post-exposure (half-lives less than 2 days). Taken together, this study firstly demonstrated that in addition to alkylation, N-nitrosodialkylamines can concurrently cause oxidative damage to DNA in vivo.

  20. Time course evaluation of N-nitrosodialkylamines-induced DNA alkylation and oxidation in liver of mosquito fish

    Chao, M.-R. [Department of Occupational Safety and Health, Chung Shan Medical University, Taichung 402, Taiwan (China); Institute of Medical and Molecular Toxicology, Chung Shan Medical University, Taichung 402, Taiwan (China); Chang, Y.-Z. [Institute of Medical and Molecular Toxicology, Chung Shan Medical University, Taichung 402, Taiwan (China); Wong, R.-H. [Department of Public Health, Chung Shan Medical University, Taichung 402, Taiwan (China); Hu, C.-W. [Department of Public Health, Chung Shan Medical University, Taichung 402, Taiwan (China)], E-mail: windyhu@csmu.edu.tw

    2009-01-15

    Here we simultaneously measured N7-alkylguanines and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in liver of small fish, respectively, to assess the time course of the formation and removal of alkylation and oxidative damage to DNA caused by N-nitrosodialkylamines. Mosquito fish (Gambusia affinis) were killed at various times during (4 days) and post-exposure (16 days) to N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) alone or their combination with concentrations of 10 and 50 mg/l. The modified guanine adducts were sensitively and selectively quantitated by isotope-dilution LC-MS/MS methods. During exposure, N7-methylguanine (N7-MeG) and N7-ethylguanine (N7-EtG) in liver DNA increased with the duration and dose of N-nitrosodialkylamine exposure, while 8-oxodG was dose-dependently induced within 1 day. It was found that NDMA formed substantially more N7-alkylated guanines and 8-oxodG than NDEA on the basis of adducts formed per micromolar concentration, suggesting that NDMA can be more easily bioactivated than NDEA to form reactive alkylating agents with the concomitant formation of oxygen radicals. After cessation of exposure, N7-alkylguanines remained elevated for 1 day and then gradually decreased over time but still higher than the background levels, even at day 16 (half-lives of 7-8 days). However, 8-oxodG was excised quickly from liver DNA and returned to the background level within 4 days post-exposure (half-lives less than 2 days). Taken together, this study firstly demonstrated that in addition to alkylation, N-nitrosodialkylamines can concurrently cause oxidative damage to DNA in vivo.

  1. Oxidative stress and inflammation generated DNA damage by exposure to air pollution particles

    Møller, Peter; Danielsen, Pernille Høgh; Karottki, Dorina Gabriela

    2014-01-01

    at different locations (spatial variability), times (temporal variability) or particle size fraction across different experimental systems of acellular conditions, cultured cells, animals and humans. Nevertheless, there is substantial variation in the genotoxic, inflammation and oxidative stress potential......Generation of oxidatively damaged DNA by particulate matter (PM) is hypothesized to occur via production of reactive oxygen species (ROS) and inflammation. We investigated this hypothesis by comparing ROS production, inflammation and oxidatively damaged DNA in different experimental systems...... investigating air pollution particles. There is substantial evidence indicating that exposure to air pollution particles was associated with elevated levels of oxidatively damaged nucleobases in circulating blood cells and urine from humans, which is supported by observations of elevated levels of genotoxicity...

  2. Body iron is a contributor to oxidative damage of DNA

    Tuomainen, Tomi-Pekka; Loft, Steffen; Nyyssönen, Kristiina

    2007-01-01

    The transition metal iron is catalytically highly active in vitro, and not surprisingly, body iron has been suggested to promote oxidative stress in vivo. In the current analysis we studied the association of serum ferritin concentration and serum soluble transferrin receptor concentration.......17 (95% CI 0.08-0.26, P = 0.001), and serum soluble transferrin receptor to ferritin concentration ratio (TfR/ferritin) predicted the excretion rate at B = - 0.13 (95% CI - 0.21 to - 0.05, P = 0.002). Our data suggest that body iron contributes to excess oxidative stress already at non-iron overload...

  3. Effective Removal of Hexavalent Chromium from Aqueous Solutions Using Ionic Liquid Modified Graphene Oxide Sorbent

    A. Nasrollahpour

    2017-10-01

    Full Text Available Ionic liquid modified reduced graphene oxide (IL-rGO was prepared and examined for chromate removal. The sorbent was characterized by N2 adsorption-desorption measurement (BET, transmission electron microscopy (TEM, powder X-ray diffraction (XRD, and X-ray photoelectron spectroscopy (XPS analysis. The sorption behavior of chromate on the ionic liquid modified reduced graphene oxide sorbent from an aqueous medium was studied by varying the parameters such as contact time, initial chromate concentration, pH, and agitation speed. The results showed that sorption kinetics of chromate by IL-rGO follows the pseudo second order, which indicates that the sorption mechanism is both chemical and physical interaction. The sorption isotherm studies revealed that Langmuir model provided the best fit to all the experimental data with an adsorption capacity of 232.55 mg g–1 for IL-rGO. Thermodynamic parameters, such as Gibbs free energy (–2.85 kJ mol–1 at 298 K, enthalpy (55.41 kJ mol–1, and entropy (11.64 J mol–1 K–1 of sorption of the chromate on ionic liquid modified reduced graphene oxide was evaluated, and it was found that the reaction was spontaneous and endothermic in nature.

  4. Seasonal variability of oxidative stress markers in city bus drivers. Part I. Oxidative damage to DNA.

    Rossner, Pavel; Svecova, Vlasta; Milcova, Alena; Lnenickova, Zdena; Solansky, Ivo; Sram, Radim J

    2008-07-03

    We investigated the seasonal variability of 8-oxodeoxyguanosine (8-oxodG), a marker of oxidative damage to DNA, in urine of 50 bus drivers and 50 controls in Prague, Czech Republic, in three seasons with different levels of air pollution: winter 2005, summer 2006 and winter 2006. The exposure to environmental pollutants (carcinogenic polycyclic aromatic hydrocarbons, c-PAHs, particulate matter (PM), and volatile organic compounds (VOC)) was monitored by personal and/or stationary monitors. For the analysis of 8-oxodG levels, the ELISA technique was used. Bus drivers were exposed to significantly higher levels of c-PAHs in winter 2006, while in the other two seasons the exposure of controls was unexpectedly higher than that of bus drivers. We did not see any difference in VOC exposure between both groups in summer 2006 and in winter 2006; VOC were not monitored in winter 2005. 8-OxodG levels were higher in bus drivers than in controls in all seasons. The median levels of 8-oxodG (nmol/mmol creatinine) in bus drivers vs. controls were as follows: winter 2005: 7.79 vs. 6.12 (p=0.01); summer 2006: 6.91 vs. 5.11 (p<0.01); winter 2006: 5.73 vs. 3.94 (p<0.001). Multivariate logistic regression analysis identified PM2.5 and PM10 levels, measured by stationary monitors during a 3-day period before urine collection, as the only factors significantly affecting 8-oxodG levels, while the levels of c-PAHs had no significant influence.

  5. Exposure to Ultrafine Particles from Ambient Air and Oxidative Stress-Induced DNA Damage

    Bräuner, Elvira Vaclavik; Forchhammer, Lykke; Møller, Peter

    2007-01-01

    mononuclear cells (PBMCs) during controlled exposure to urban air particles with assignment of number concentration (NC) to four size modes with average diameters of 12, 23, 57, and 212 nm. DESIGN. Twenty-nine healthy adults participated in a randomized, two-factor cross-over study with or without biking...... exercise for 180 min and with exposure to particles (NC 6169-15362/cm3) or filtered air (NC 91-542/cm3) for 24 hr. METHODS: The levels of DNA strand breaks (SBs), oxidized purines as formamidopyrimidine DNA glycolase (FPG) sites, and activity of 7,8-dihydro-8-oxoguanine-DNA glycosylase (OGG1) in PBMCs were...

  6. Correction of the lack of commutability between plasmid DNA and genomic DNA for quantification of genetically modified organisms using pBSTopas as a model.

    Zhang, Li; Wu, Yuhua; Wu, Gang; Cao, Yinglong; Lu, Changming

    2014-10-01

    Plasmid calibrators are increasingly applied for polymerase chain reaction (PCR) analysis of genetically modified organisms (GMOs). To evaluate the commutability between plasmid DNA (pDNA) and genomic DNA (gDNA) as calibrators, a plasmid molecule, pBSTopas, was constructed, harboring a Topas 19/2 event-specific sequence and a partial sequence of the rapeseed reference gene CruA. Assays of the pDNA showed similar limits of detection (five copies for Topas 19/2 and CruA) and quantification (40 copies for Topas 19/2 and 20 for CruA) as those for the gDNA. Comparisons of plasmid and genomic standard curves indicated that the slopes, intercepts, and PCR efficiency for pBSTopas were significantly different from CRM Topas 19/2 gDNA for quantitative analysis of GMOs. Three correction methods were used to calibrate the quantitative analysis of control samples using pDNA as calibrators: model a, or coefficient value a (Cva); model b, or coefficient value b (Cvb); and the novel model c or coefficient formula (Cf). Cva and Cvb gave similar estimated values for the control samples, and the quantitative bias of the low concentration sample exceeded the acceptable range within ±25% in two of the four repeats. Using Cfs to normalize the Ct values of test samples, the estimated values were very close to the reference values (bias -13.27 to 13.05%). In the validation of control samples, model c was more appropriate than Cva or Cvb. The application of Cf allowed pBSTopas to substitute for Topas 19/2 gDNA as a calibrator to accurately quantify the GMO.

  7. Enhanced bioremediation of oil contaminated soil by graded modified Fenton oxidation.

    Xu, Jinlan; Xin, Lei; Huang, Tinglin; Chang, Kun

    2011-01-01

    Graded modified Fenton's (MF) oxidation is a strategy in which H2O2 is added intermittently to prevent a sharp temperature increase and undesired soil sterilization at soil circumneutral pH versus adding the same amount of H2O2 continuously. The primary objective of the present study was to investigate whether a mild MF pre-oxidation such as a stepwise addition of H2O2 can prevent sterilization and achieve a maximum degradation of tank oil in soil. Optimization experiments of graded MF oxidation were conducted using citric acid, oxalic acid and SOLV-X as iron chelators under different frequencies of H2O2 addition. The results indicated that the activity order of iron chelates decreased as: citric acid (51%) > SOLV-X (44%) > oxalic acid (9%), and citric acid was found to be an optimized iron chelating agent of graded MF oxidation. Three-time addition of H2O2 was found to be favorable and economical due to decreasing total petroleum hydrocarbon removal from three time addition (51%) to five time addition (59%). Biological experiments were conducted after graded MF oxidation of tank oil completed under optimum conditions mentioned above. After graded oxidation, substantially higher increase (31%) in microbial activity was observed with excessive H2O2 (1470 mmol/L, the mol ratio of H2O2:Fe2+ was 210:1) than that of non-oxidized soil. Removal efficiency of tank oil was up to 93% after four weeks. Especially, the oil fraction (C10-C40) became more biodagradable after graded MF oxidation than its absence. Therefore, graded MF oxidation is a mild pretreatment to achieve an effective bioremediation of oil contaminated soil.

  8. Electrodeposited nickel oxide and graphene modified carbon ionic liquid electrode for electrochemical myglobin biosensor

    Sun, Wei; Gong, Shixing; Deng, Ying; Li, Tongtong; Cheng, Yong; Wang, Wencheng; Wang, Lei

    2014-01-01

    By using ionic liquid 1-hexylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE) as the substrate electrode, graphene (GR) and nickel oxide (NiO) were in situ electrodeposited step by step to get a NiO/GR nanocomposite modified CILE. Myoglobin (Mb) was further immobilized on the surface of NiO/GR/CILE with a Nafion film to get the electrochemical sensor denoted as Nafion/Mb/NiO/GR/CILE. Cyclic voltammetric experiments indicated that a pair of well-defined quasi-reversible redox peaks appeared in pH 3.0 phosphate buffer solution with the formal peak potential (E 0′ ) located at − 0.188 V (vs. SCE), which was the typical characteristics of Mb Fe(III)/Fe(II) redox couples. So the direct electron transfer of Mb was realized and promoted due to the presence of the NiO/GR nanocomposite on the electrode. Based on the cyclic voltammetric data, the electrochemical parameters of Mb on the modified electrode were calculated. The Mb modified electrode showed an excellent electrocatalytic activity towards the reduction of different substrates including trichloroacetic acid and H 2 O 2 . Therefore a third-generation electrochemical Mb biosensor based on NiO/GR/CILE was constructed with good stability and reproducibility. - Highlights: • Graphene and nickel oxide nanocomposites were prepared by electrodeposition. • Electrochemical myoglobin sensor was prepared on a nanocomposite modified electrode. • Direct electrochemistry and electrocatalysis of myglobin were realized

  9. Application of graphene oxide/lanthanum-modified carbon paste electrode for the selective determination of dopamine

    Ye, Fengying; Feng, Chenqi; Fu, Ning; Wu, Huihui; Jiang, Jibo, E-mail: jibojiang0506@163.com; Han, Sheng, E-mail: hansheng654321@sina.com

    2015-12-01

    Highlights: • The effective surface area of the modified CPE has been expanded after self-assembly. • The GO–La composite exhibited excellent electrocatalytic activity toward DA. • The GO–La/CPE presented high selectivity, sensitivity, excellent stability and repeatability. - Abstract: A home-made carbon paste electrode (CPE) was reformed by graphene oxide (GO)/lanthanum (La) complexes, and a modified electrode, called GO–La/CPE, was fabricated for the selective determination of dopamine (DA) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Several factors affecting the electrocatalytic performance of the modified sensor were investigated. Owning to the combination of GO and La ions, the GO–La/CPE sensor exhibited large surface area, well selectivity, good repeatability and stability in the oxidation reaction of DA. At optimal conditions, the response of the GO–La/CPE electrode for determining DA was linear in the region of 0.01–0.1 μM and 0.1–400.0 μM. The limit of detection was down to 0.32 nM (S/N = 3). In addition, this modified electrode was successfully applied to the detection of DA in real urine and serum samples by using standard adding method, showing its promising application in the electroanalysis of real samples.

  10. Association between high risk papillomavirus DNA and nitric oxide release in the human uterine cervix.

    Rahkola, Paivi; Mikkola, Tomi S; Ylikorkala, Olavi; Vaisanen-Tommiska, Mervi

    2009-08-01

    Local cervical factors may determine the outcome of human papillomavirus (HPV) infection. Nitric oxide (NO) may be one such factor, since it is produced by uterine cervical cells and it takes part in both immunological and carcinogenic reactions. We studied the association between the presence of cervical high risk (hr) HPV DNA and NO in the cervical canal in women. High risk HPV DNA status was assessed from 328 women by using a specific DNA test and the release of cervical NO was assessed as nitrate/nitrite in cervical fluid. Cervical NO was then compared between women showing different status of hr HPV DNA and different cytological and histological findings. High risk HPV DNA was present in 175/328 (53%) women. The cervical NO release in women with hr HPV DNA was 90% higher compared to hr HPV DNA negative women (poral contraception, intrauterine devices, or signs of bacterial vaginosis or candida infection. Cytologically healthy epithelium and epithelium with mild cytological or histological changes showed elevated NO release if hr HPV DNA was present. The presence of hr HPV DNA is associated with an increased release of NO in the human uterine cervix. The clinical significance of this phenomenon remains open.

  11. Facile synthesis of Graphene Oxide/Double-stranded DNA ...

    Investigation of the interactions between graphene oxide (GO) and biomolecules is very crucialfor the development of biomedical applications based on GO. This study reports the first observation of thespontaneous formation of self-assembled liquid crystals and three-dimensional hydrogels of graphene oxidewith ...

  12. Clad modified optical fiber gas sensors based on nanocrystalline nickel oxide embedded coatings

    Yamini, K.; Renganathan, B.; Ganesan, A. R.; Prakash, T.

    2017-07-01

    A clad modified optical fiber gas sensor for sensing volatile organic compound vapours (VOCs) such as formaldehyde (HCHO), ammonia (NH3), ethanol (C2H5OH) and methanol (CH3OH) up to 500 ppm was studied using nanocrystalline nickel oxide embedded coatings. Prior to the measurements, nickel oxide in two different crystallite sizes such as 24 nm and 76 nm was synthesized by calcination of reverse precipitated nickel hydroxide subsequently at 450 °C and 900 °C for 30 min. Then, samples physical properties were characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). Our gas sensing measurement concludes that the lower crystallite size (24 nm) nickel oxide nanocrystals exhibits superior performance to formaldehyde and ethanol vapours as compared with other two VOCs, the observed experimental results were discussed in detail.

  13. Macromolecule oxidation and DNA repair in mussel (Mytilus edulis L.) gill following exposure to Cd and Cr(VI)

    Emmanouil, C.; Sheehan, T.M.T.; Chipman, J.K.

    2007-01-01

    The oxidation of DNA and lipid was analysed in the marine mussel (Mytilus edulis) in response to exposure (10 μg/l and 200 μg/l) to cadmium (Cd) and chromium [Cr(VI)]. Concentration dependent uptake of both metals into mussel tissues was established and levels of gill ATP were not depleted at these exposure levels. DNA strand breakage in gill cells (analysed by the comet assay) was elevated by both metals, however, DNA oxidation [measured by DNA strand breakage induced by the DNA repair enzyme formamidopyrimidine glycosylase (FPG)] was not elevated. This was despite a statistically significant increase in both malondialdehyde and 4-hydroxynonenal - indicative of lipid peroxidation - following treatment with Cd. In contrast, both frank DNA stand breaks and FPG-induced DNA strand breaks (indicative of DNA oxidation) were increased following injection of mussels with sodium dichromate (10.4 μg Cr(VI)/mussel). The metals also showed differential inhibitory potential towards DNA repair enzyme activity with Cd exhibiting inhibition of DNA cutting activity towards an oligonucleotide containing 8-oxo-7,8-dihydro-2'-deoxyguanosine and Cr(VI) showing inhibition of such activity towards an oligonucleotide containing ethenoadenosine, both at 200 μg/l. The metals thus show DNA damage activity in mussel gill with distinct mechanisms involving both direct and indirect (oxidative) DNA damage, as well as impairing different DNA repair capacities. A combination of these activities can contribute to adverse effects in these organisms

  14. Resveratrol induces membrane and DNA disruption via pro-oxidant activity against Salmonella typhimurium.

    Lee, Wonjong; Lee, Dong Gun

    2017-07-22

    Resveratrol is a flavonoid found in various plants including grapes, which has been reported to be active against various pathogenic bacteria. However, antibacterial effects and mechanisms via pro-oxidant property of resveratrol remain unknown and speculative. This research investigated antibacterial mechanism of resveratrol against a food-borne human pathogen Salmonella typhimurium, and confirmed the cell death associated oxidative damage. Resveratrol increased outer membrane permeability and membrane depolarization. It also was observed DNA injury responses such as DNA fragmentation, increasing DNA contents and cell division inhibition. Intracellular ROS accumulation, GSH depletion and significant increased malondialdehyde levels were confirmed, which indicated pro-oxidant activity of resveratrol and oxidative stress. Furthermore, the observed lethal damages were reduced by antioxidant N-acetylcysteine treatment supported the view that resveratrol-induced oxidative stress stimulated S. typhimurium cell death. In conclusion, this study expands understanding on role of pro-oxidant property and insight into previously unrecognized oxygen-dependent anti-Salmonella mechanism on resveratrol. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Oxidative stress and alterations in DNA methylation: two sides of the same coin in reproduction.

    Menezo, Yves J R; Silvestris, Erica; Dale, Brian; Elder, Kay

    2016-12-01

    The negative effect of oxidative stress on the human reproductive process is no longer a matter for debate. Oxidative stress affects female and male gametes and the developmental capacity of embryos. Its effect can continue through late stages of pregnancy. Metabolic disorders and psychiatric problems can also be caued by DNA methylation and epigenetic errors. Age has a negative effect on oxidative stress and DNA methylation, and recent observations suggest that older men are at risk of transmitting epigenetic disorders to their offspring. Environmental endocrine disruptors can also increase oxidative stress and methylation errors. Oxidative stress and DNA methylation feature a common denominator: the one carbon cycle. This important metabolic pathway stimulates glutathione synthesis and recycles homocysteine, a molecule that interferes with the process of methylation. Glutathione plays a pivotal role during oocyte activation, protecting against reactive oxygen species. Assisted reproductive techniques may exacerbate defects in methylation and epigenesis. Antioxidant supplements are proposed to reduce the risk of potentially harmful effects, but their use has failed to prevent problems and may sometimes be detrimental. New concepts reveal a significant correlation between oxidative stress, methylation processes and epigenesis, and have led to changes in media composition with positive preliminary clinical consequences. Copyright © 2016 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

  16. Role of oxidative stress and DNA hydroxymethylation in the neurotoxicity of fine particulate matter

    Wei, Hongying; Feng, Yan; Liang, Fan; Cheng, Wei; Wu, Xiaomeng; Zhou, Ren; Wang, Yan

    2017-01-01

    Highlights: • Oxidative stress-mediated neurocytotoxicity and DNA hydroxymethylation abnormalities involved in neuronal pathology of PM 2.5 . • PM 2.5 particles and toxic compounds adsorbed on the particle caused different types of neurocytotoxicity. • DNA hydroxymethylation abnormalities participated in PM 2.5 -induced impairments in neurite outgrowth and synapse formation. - Abstract: Epidemiological studies have implicated fine particulate matter (PM 2.5 ) as a risk factor for neurodegenerative diseases and neurodevelopmental disorders. However, the underlying molecular mechanisms and the influences of different components remain largely elusive. Here, we extended our previous work to investigate the role of oxidative stress and DNA hydroxymethylation in neuronal pathology of PM 2.5 . We found PM 2.5 and its extracts (water-soluble extracts, organic extracts and carbon core component) differentially caused cell cycle arrest, cell apoptosis and the cell proliferation inhibition in neuronal cells. These effects were mechanistically related to each other and oxidative stress, suggesting PM 2.5 and toxic compounds adsorbed on the particles may cause different types of brain damages. In addition, PM 2.5 and its organic extracts increased global DNA hydroxymethylation and gene-specific DNA hydroxymethylation of neuronal genes, and subsequently interfered with their mRNA expression. The impairments in neuronal progression characterized with decreased length of neurite and reduced mRNA expression of neuronal markers and synaptic markers. The blocking effects of antioxidants demonstrated the involvement of oxidative stress-mediated hydroxymethylation abnormalities in PM 2.5 -induced defects in neurite outgrowth and synapse formation. Our results first revealed the role of oxidative stress-mediated abnormal DNA hydroxymethylation in neuronal impairments of PM 2.5 , and thoroughly evaluated the neurocytotoxicity of different components.

  17. Oxidative stress and DNA repair and detoxification gene expression in adolescents exposed to heavy metals living in the Milazzo-Valle del Mela area (Sicily, Italy

    Gabriele Pizzino

    2014-01-01

    Conclusions: Continuous exposure at relatively low concentrations of heavy metals is associated with increased oxidative DNA damage and impaired expression of DNA repair and detoxification genes in adolescents.

  18. Mitochondrial DNA (mtDNA haplogroups and serum levels of anti-oxidant enzymes in patients with osteoarthritis

    Fernandez-Moreno Mercedes

    2011-11-01

    Full Text Available Abstract Background Oxidative stress play a main role in the initiation and progression of the OA disease and leads to the degeneration of mitochondria. To prevent this, the chondrocytes possess a well-coordinated enzymatic antioxidant system. Besides, the mitochondrial DNA (mtDNA haplogroups are associated with the OA disease. Thus, the main goal of this work is to assess the incidence of the mtDNA haplogroups on serum levels of two of the main antioxidant enzymes, Manganese Superoxide Dismutase (Mn-SOD or SOD2 and catalase, and to test the suitability of these two proteins for potential OA-related biomarkers. Methods We analyzed the serum levels of SOD2 and catalase in 73 OA patients and 77 healthy controls carrying the haplogroups J, U and H, by ELISA assay. Knee and hip radiographs were classified according to Kellgren and Lawrence (K/L scoring from Grade 0 to Grade IV. Appropriate statistical analyses were performed to test the effects of clinical variables, including gender, body mass index (BMI, age, smoking status, diagnosis, haplogroups and radiologic K/L grade on serum levels of these enzymes. Results Serum levels of SOD2 appeared statistically increased in OA patients when compared with healthy controls (p Conclusions The increased levels of SOD2 in OA patients indicate an increased oxidative stress OA-related, therefore this antioxidant enzyme could be a suitable candidate biomarker for diagnosis of OA. Mitochondrial haplogroups significantly correlates with serum levels of catalase

  19. Enhanced oxidation and detection of toxic ractopamine using carbon nanotube film-modified electrode

    Liu Zhuan; Zhou Yikai; Wang Yanying; Cheng Qin; Wu Kangbing

    2012-01-01

    Highlights: ► The enhanced oxidation of ractopamine on MWCNT film surface was firstly studied. ► The oxidation occurred at phenolic hydroxyl groups and transferred two electrons. ► A sensitive and effective electrochemical sensor was developed for ractopamine. ► It was used to detect ractopamine in animal tissues, the recovery was satisfactory. - Abstract: Insoluble multi-walled carbon nanotube (MWCNT) was readily dispersed into water in the presence of dihexadecyl hydrogen phosphate, and then used to modify the surface of glassy carbon electrode (GCE) by means of solvent evaporation. Scanning electron microscopy test indicated that the GCE surface was coated with uniform MWCNT film. The resulting MWCNT film-modified GCE greatly enhanced the oxidation signal of ractopamine. The oxidation mechanism was studied, and it was found that the oxidation of ractopamine occurred at two phenolic hydroxyl groups, involving two protons and two electrons. Moreover, the influences of pH value, amount of MWCNT, accumulation potential and time were investigated on the oxidation signal of ractopamine. Based on the strong enhancement effect of MWCNT, a sensitive, rapid and simple electrochemical method was developed for the detection of ractopamine. The linear range was from 50 μg L −1 to 2 mg L −1 , and the detection limit was 20 μg L −1 . Finally, this method was successfully used to detect the content of ractopamine in pork and liver samples, and the recovery was in the range from 93.1% to 107.2%.

  20. A Comparative Study of the Characteristics of Cross-Linked, Oxidized and Dual-Modified Rice Starches

    Xiao, Hua-Xi; Lin, Qin-Lu; Liu, Gao-Qiang; Yu, Feng-Xiang

    2012-01-01

    Rice starch was cross-linked with epichlorohydrin (0.3%, w/w, on a dry starch basis) and oxidized with sodium hypochlorite (2.5% w/w), respectively. Two dual-modified rice starch samples (oxidized cross-linked rice starch and cross-linked oxidized rice starch) were obtained by the oxidation of cross-linked rice starch and the cross-linking of oxidized rice starch at the same level of reagents. The physicochemical properties of native rice starch, cross-linked rice starch and oxidized rice sta...

  1. Assessment of DNA degradation induced by thermal and UV radiation processing: implications for quantification of genetically modified organisms.

    Ballari, Rajashekhar V; Martin, Asha

    2013-12-01

    DNA quality is an important parameter for the detection and quantification of genetically modified organisms (GMO's) using the polymerase chain reaction (PCR). Food processing leads to degradation of DNA, which may impair GMO detection and quantification. This study evaluated the effect of various processing treatments such as heating, baking, microwaving, autoclaving and ultraviolet (UV) irradiation on the relative transgenic content of MON 810 maize using pRSETMON-02, a dual target plasmid as a model system. Amongst all the processing treatments examined, autoclaving and UV irradiation resulted in the least recovery of the transgenic (CaMV 35S promoter) and taxon-specific (zein) target DNA sequences. Although a profound impact on DNA degradation was seen during the processing, DNA could still be reliably quantified by Real-time PCR. The measured mean DNA copy number ratios of the processed samples were in agreement with the expected values. Our study confirms the premise that the final analytical value assigned to a particular sample is independent of the degree of DNA degradation since the transgenic and the taxon-specific target sequences possessing approximately similar lengths degrade in parallel. The results of our study demonstrate that food processing does not alter the relative quantification of the transgenic content provided the quantitative assays target shorter amplicons and the difference in the amplicon size between the transgenic and taxon-specific genes is minimal. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Lactoferrin modified graphene oxide iron oxide nanocomposite for glioma-targeted drug delivery.

    Song, Meng-Meng; Xu, Huai-Liang; Liang, Jun-Xing; Xiang, Hui-Hui; Liu, Rui; Shen, Yu-Xian

    2017-08-01

    Targeting delivery of drugs in a specific manner represents a potential powerful technology in gliomas. Herein, we prepared a multifunctional targeted delivery system based on graphene oxide (GO) that contains a molecular bio-targeting ligand and superparamagnetic iron oxide nanoparticles on the surface of GO for magnetic targeting. Superparamagnetic Fe 3 O 4 nanoparticles was loaded on the surface of GO via chemical precipitation method to form GO@Fe 3 O 4 nanocomposites. Lactoferrin (Lf), an iron-transporting serum glycoprotein that binds to receptors overexpressed at the surface of glioma cells and vascular endothelial cell of the blood brain barrier, was chosen as the targeted ligand to construct the targeted delivery system Lf@GO@Fe 3 O 4 through EDC/NHS chemistry. With the confirmation of TEM, DLS and VSM, the resulting Lf@GO@Fe 3 O 4 had a size distribution of 200-1000nm and exhibited a superparamagnetic behavior. The nano delivery system had a high loading capacity and exhibited a pH-dependent release behavior. Compared with free DOX and DOX@GO@Fe 3 O 4 , Lf@GO@Fe 3 O 4 @DOX displayed greater intracellular delivery efficiency and stronger cytotoxicity against C6 glioma cells. The results demonstrated the potential utility of Lf conjugated GO@Fe 3 O 4 nanocomposites for therapeutic application in the treatment of gliomas. Copyright © 2017. Published by Elsevier B.V.

  3. Oxidative DNA damage in bone marrow cells of patients with low-risk myelodysplastic syndrome

    Novotná, Božena; Bagryantseva, Yana; Šišková, M.; Neuwirtová, R.

    2009-01-01

    Roč. 33, č. 2 (2009), s. 340-343 ISSN 0145-2126 R&D Projects: GA MZd NR8265 Institutional research plan: CEZ:AV0Z50390512 Keywords : Myelodysplastic syndrome * Refractory anemia * Oxidative DNA damage Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.358, year: 2009

  4. Radiation-induced oxidative damage to the DNA-binding domain of the lactose repressor

    Gillard, N.; Goffinont, S.; Buré, C.; Davídková, Marie; Maurizot, J. C.; Cadene, M.; Spotheim-Maurizot, M.

    2007-01-01

    Roč. 403, part 3 (2007), s. 463-472 ISSN 0264-6021 R&D Projects: GA MŠk 1P05OC085 Institutional research plan: CEZ:AV0Z10480505 Keywords : ionizing radiation * oxidative damage * DNA binding domain * lac repressor Subject RIV: CE - Biochemistry Impact factor: 4.009, year: 2007

  5. Base excision repair of oxidative DNA damage and association with cancer and aging

    Maynard, Scott; Schurman, Shepherd H; Harboe, Charlotte

    2009-01-01

    Aging has been associated with damage accumulation in the genome and with increased cancer incidence. Reactive oxygen species (ROS) are produced from endogenous sources, most notably the oxidative metabolism in the mitochondria, and from exogenous sources, such as ionizing radiation. ROS attack DNA...

  6. Selective oxidation of serotonin and norepinephrine over eriochrome cyanine R film modified glassy carbon electrode

    Yao Hong; Li Shaoguang [Department of Pharmaceutical Analysis, Faculty of Pharmacy, Fujian Medical University, Fuzhou 350004 (China); Tang Yuhai [Institute of Analytical Sciences, Xi' an Jiaotong University, Xi' an 710061 (China); Chen Yan [Department of Pharmaceutical Analysis, Faculty of Pharmacy, Fujian Medical University, Fuzhou 350004 (China); Chen Yuanzhong [Fujian Institute of Hematology, The Affiliated Union Hospital of Fujian Medical University, Fuzhou 350001 (China)], E-Mail: chenyz@pub3.fz.fj.cn; Lin Xinhua [Department of Pharmaceutical Analysis, Faculty of Pharmacy, Fujian Medical University, Fuzhou 350004 (China)], E-mail: xhlin1963@sin.com

    2009-08-01

    A novel ECR-modified electrode is fabricated by electrodeposition of Eriochrome Cyanine R (ECR) at a glassy carbon (GC) electrode by cyclic voltammetry (CV) in double-distilled water. The characterization of the ECR film modified electrode is carried out by atomic force microscopy (AFM), infrared spectra (IR), spectroelectrochemistry and cyclic voltammetry. The results show that a slightly heterogeneous film formed on the surface of the modified electrode, and the calculated surface concentration of ECR is 2 x 10{sup -10} mol/cm{sup -2}. The ECR film modified GC electrode shows excellent electrocatalytic activities toward the oxidation of serotonin (5-HT) and norepinephrine (NE). Furthermore, the modified electrode can separately detect 5-HT and NE, even in the presence of 200-fold concentration of ascorbic acid (AA) and 25-fold concentration of uric acid (UA). Using differential pulse voltammetry (DPV), the peak currents of 5-HT and NE recorded in pH 7 solution are linearly dependent on their concentrations in the range of 0.05-5 {mu}M and 2-50 {mu}M, respectively. The limits of detection are 0.05 and 1.5 {mu}M for 5-HT and NE, respectively. The ECR film modified electrode can be stored stable for at least 1 week in 0.05 M PBS (pH 7) at 4 {sup o}C in a refrigerator. Owing to its excellent selectivity and sensitivity, the modified electrode could provide a promising tool for the simultaneous determination of 5-HT and NE in complex biosamples.

  7. DNA-hosted copper nanoclusters/graphene oxide based fluorescent biosensor for protein kinase activity detection.

    Wang, Mengke; Lin, Zihan; Liu, Qing; Jiang, Shan; Liu, Hua; Su, Xingguang

    2018-07-05

    A novel fluorescent biosensor for protein kinase activity (PKA) detection was designed by applying double-strands DNA-hosted copper nanoclusters (dsDNA-CuNCs) and graphene oxide (GO). One DNA strand of the dsDNA consisted of two domains, one domain can hybridize with another complementary DNA strand to stabilize the fluorescent CuNCs and another domain was adenosine 5'-triphosphate (ATP) aptamer. ATP aptamer of the dsDNA-CuNCs would be spontaneously absorbed onto the GO surface through π-π stacking interactions. Thus GO can efficiently quench the fluorescence (FL) of dsDNA-CuNCs through fluorescence resonance energy transfer (FRET). In the present of ATP, ATP specifically combined with ATP aptamer to form ATP-ATP aptamer binding complexes, which had much less affinity to GO, resulting in the fluorescence recovery of the system. Nevertheless, in the presence of PKA, ATP could be translated into ADP and ADP could not combine with ATP aptamer resulting in the fluorescence quenching of dsDNA-CuNCs again. According to the change of the fluorescence signal, PKA activity could be successfully monitored in the range of 0.1-5.0 U mL -1 with a detection limit (LOD) of 0.039 U mL -1 . Besides, the inhibitory effect of H-89 on PKA activity was studied. The sensor was performed for PKA activity detection in cell lysates with satisfactory results. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Degradation and half-life of DNA present in biomass from a genetically-modified organism during land application.

    Halter, Mathew C; Zahn, James A

    2017-02-01

    White biotechnology has made a positive impact on the chemical industry by providing safer, more efficient chemical manufacturing processes that have reduced the use of toxic chemicals, harsh reaction conditions, and expensive metal catalysts, which has improved alignment with the principles of Green Chemistry. The genetically-modified (GM) biocatalysts that are utilized in these processes are typically separated from high-value products and then recycled, or eliminated. Elimination routes include disposal in sanitary landfills, incineration, use as a fuel, animal feed, or reuse as an agricultural soil amendment or other value-added products. Elimination routes that have the potential to impact the food chain or environment have been more heavily scrutinized for the fate and persistence of biological products. In this study, we developed and optimized a method for monitoring the degradation of strain-specific DNA markers from a genetically-modified organism (GMO) used for the commercial production of 1,3-propanediol. Laboratory and field tests showed that a marker for heterologous DNA in the GM organism was no longer detectable by end-point polymerase chain reaction (PCR) after 14 days. The half-life of heterologous DNA was increased by 17% (from 42.4 to 49.7 h) after sterilization of the soil from a field plot, which indicated that abiotic factors were important in degradation of DNA under field conditions. There was no evidence for horizontal transfer of DNA target sequences from the GMO to viable organisms present in the soil.

  9. Sorbitol-modified hyaluronic acid reduces oxidative stress, apoptosis and mediators of inflammation and catabolism in human osteoarthritic chondrocytes.

    Mongkhon, John-Max; Thach, Maryane; Shi, Qin; Fernandes, Julio C; Fahmi, Hassan; Benderdour, Mohamed

    2014-08-01

    Our study was designed to elucidate the precise molecular mechanisms by which sorbitol-modified hyaluronic acid (HA/sorbitol) exerts beneficial effects in osteoarthritis (OA). Human OA chondrocytes were treated with increasing doses of HA/sorbitol ± anti-CD44 antibody or with sorbitol alone and thereafter with or without interleukin-1beta (IL-1β) or hydrogen peroxide (H2O2). Signal transduction pathways and parameters related to oxidative stress, apoptosis, inflammation, and catabolism were investigated. HA/sorbitol prevented IL-1β-induced oxidative stress, as measured by reactive oxygen species, p47-NADPH oxidase phosphorylation, 4-hydroxynonenal (HNE) production and HNE-metabolizing glutathione-S-transferase A4-4 expression. Moreover, HA/sorbitol stifled IL-1β-induced metalloproteinase-13, nitric oxide (NO) and prostaglandin E2 release as well as inducible NO synthase expression. Study of the apoptosis process revealed that this gel significantly attenuated cell death, caspase-3 activation and DNA fragmentation elicited by exposure to a cytotoxic H2O2 dose. Examination of signaling pathway components disclosed that HA/sorbitol prevented IL-1β-induced p38 mitogen-activated protein kinase and nuclear factor-kappa B activation, but not that of extracellular signal-regulated kinases 1 and 2. Interestingly, the antioxidant as well as the anti-inflammatory and anti-catabolic effects of HA/sorbitol were attributed to sorbitol and HA, respectively. Altogether, our findings support a beneficial effect of HA/sorbitol in OA through the restoration of redox status and reduction of apoptosis, inflammation and catabolism involved in cartilage damage.

  10. Titanium dioxide nanoparticles induce oxidative stress and DNA-adduct formation but not DNA-breakage in human lung cells

    Schins Roel PF

    2009-06-01

    Full Text Available Abstract Titanium dioxide (TiO2, also known as titanium (IV oxide or anatase, is the naturally occurring oxide of titanium. It is also one of the most commercially used form. To date, no parameter has been set for the average ambient air concentration of TiO2 nanoparticles (NP by any regulatory agency. Previously conducted studies had established these nanoparticles to be mainly non-cyto- and -genotoxic, although they had been found to generate free radicals both acellularly (specially through photocatalytic activity and intracellularly. The present study determines the role of TiO2-NP (anatase, ∅ in vitro. For comparison, iron containing nanoparticles (hematite, Fe2O3, ∅ 2-NP did not induce DNA-breakage measured by the Comet-assay in both cell types. Generation of reactive oxygen species (ROS was measured acellularly (without any photocatalytic activity as well as intracellularly for both types of particles, however, the iron-containing NP needed special reducing conditions before pronounced radical generation. A high level of DNA adduct formation (8-OHdG was observed in IMR-90 cells exposed to TiO2-NP, but not in cells exposed to hematite NP. Our study demonstrates different modes of action for TiO2- and Fe2O3-NP. Whereas TiO2-NP were able to generate elevated amounts of free radicals, which induced indirect genotoxicity mainly by DNA-adduct formation, Fe2O3-NP were clastogenic (induction of DNA-breakage and required reducing conditions for radical formation.

  11. Conductometric gas sensors based on metal oxides modified with gold nanoparticles: a review

    Korotcenkov, Ghenadii; Cho, Beong K.; Brinzari, Vladimir

    2016-01-01

    This review (with 170 refs.) discusses approaches towards surface functionalizaton of metal oxides by gold nanoparticles, and the application of the resulting nanomaterials in resistive gas sensors. The articles is subdivided into sections on (a) methods for modification of metal oxides with gold nanoparticles; (b) the response of gold nanoparticle-modified metal oxide sensors to gaseous species, (c) a discussion of the limitations of such sensors, and (d) a discussion on future tasks and trends along with an outlook. It is shown that, in order to achieve significant improvements in sensor parameters, it is necessary to warrant a good control the size and density of gold nanoparticles on the surface of metal oxide crystallites, the state of gold in the cluster, and the properties of the metal oxide support. Current challenges include an improved reproducibility of sensor preparation, better long-term stabilities, and a better resistance to sintering and poisoning of gold clusters during operation. Additional research focused on better understanding the role of gold clusters and nanoparticles in gas-sensing effects is also required. (author)

  12. Enhancement of fluorescence quenching and exciplex formation in DNA major groove by double incorporation of modified fluorescent deoxyuridines.

    Tanaka, Makiko; Oguma, Kazuhiro; Saito, Yoshio; Saito, Isao

    2012-06-15

    5-(1-Naphthalenylethynyl)-2'-deoxyuridine ((N)U) and 5-[(4-cyano-1-naphthalenyl)ethynyl]-2'-deoxyuridine ((CN)U) were synthesized and incorporated into oligodeoxynucleotides. Fluorescence emissions of modified duplexes containing double (N)U were efficiently quenched depending upon the sequence pattern of the naphthalenes in DNA major groove, as compared to the duplex possessing single (N)U. When one of the naphthalene moieties has a cyano substituent, the exciplex emission from the chromophores in DNA major groove was observed at longer wavelength. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. The Application of a Modified d-ROMs Test for Measurement of Oxidative Stress and Oxidized High-Density Lipoprotein

    Fumiaki Ito

    2017-02-01

    Full Text Available Reactive oxygen species (ROS are involved in the initiation and progression of atherosclerosis. ROS-derived hydroperoxides, as an indicator of ROS production, have been measured by using the diacron reactive oxygen metabolites (d-ROMs test, which requires iron-containing transferrin in the reaction mixture. In this study we developed a modified d-ROMs test, termed the Fe-ROMs test, where iron ions were exogenously added to the reaction mixture. This modification is expected to exclude the assay variation that comes from different blood iron levels in individuals. In addition, this Fe-ROMs test was helpful for determining the class of plasma lipoproteins that are hydroperoxidized. Low-density lipoprotein/very low-density lipoprotein (LDL/VLDL and high-density lipoprotein (HDL were purified by use of an LDL/VLDL purification kit and the dextran sulfate-Mg2+ precipitation method, respectively; their hydroperoxide contents were assessed by performing the Fe-ROMs test. The majority of the hydroperoxides were detected only in the HDL fraction, not in the LDL/VLDL. Further detailed analysis of HDLs by size-exclusion high-performance liquid chromatography revealed that the hydroperoxide-containing molecules were small-sized HDLs. Because HDL was shown to be the principal vehicle for the plasma hydroperoxides, this Fe-ROMs test is a beneficial method for the assessment of oxidized-HDL levels. Indeed, Fe-ROMs levels were strongly associated with the levels of oxidized HDL, which were determined by performing the malondialdehyde-modified HDL enzyme immunoassay. In conclusion, the Fe-ROMs test using plasma itself or the HDL fraction after dextran sulfate-Mg2+ precipitation is useful to assess the functionality of HDL, because the oxidation of HDL impairs its antiatherogenic capacity.

  14. Simultaneous Electrochemical Detection of Dopamine and Ascorbic Acid Using an Iron Oxide/Reduced Graphene Oxide Modified Glassy Carbon Electrode

    Teo Peik-See

    2014-08-01

    Full Text Available The fabrication of an electrochemical sensor based on an iron oxide/graphene modified glassy carbon electrode (Fe3O4/rGO/GCE and its simultaneous detection of dopamine (DA and ascorbic acid (AA is described here. The Fe3O4/rGO nanocomposite was synthesized via a simple, one step in-situ wet chemical method and characterized by different techniques. The presence of Fe3O4 nanoparticles on the surface of rGO sheets was confirmed by FESEM and TEM images. The electrochemical behavior of Fe3O4/rGO/GCE towards electrocatalytic oxidation of DA was investigated by cyclic voltammetry (CV and differential pulse voltammetry (DPV analysis. The electrochemical studies revealed that the Fe3O4/rGO/GCE dramatically increased the current response against the DA, due to the synergistic effect emerged between Fe3O4 and rGO. This implies that Fe3O4/rGO/GCE could exhibit excellent electrocatalytic activity and remarkable electron transfer kinetics towards the oxidation of DA. Moreover, the modified sensor electrode portrayed sensitivity and selectivity for simultaneous determination of AA and DA. The observed DPVs response linearly depends on AA and DA concentration in the range of 1–9 mM and 0.5–100 µM, with correlation coefficients of 0.995 and 0.996, respectively. The detection limit of (S/N = 3 was found to be 0.42 and 0.12 µM for AA and DA, respectively.

  15. One-electron oxidation reactions of purine and pyrimidine bases in cellular DNA.

    Cadet, Jean; Wagner, J Richard; Shafirovich, Vladimir; Geacintov, Nicholas E

    2014-06-01

    The aim of this survey is to critically review the available information on one-electron oxidation reactions of nucleobases in cellular DNA with emphasis on damage induced through the transient generation of purine and pyrimidine radical cations. Since the indirect effect of ionizing radiation mediated by hydroxyl radical is predominant in cells, efforts have been made to selectively ionize bases using suitable one-electron oxidants that consist among others of high intensity UVC laser pulses. Thus, the main oxidation product in cellular DNA was found to be 8-oxo-7,8-dihydroguanine as a result of direct bi-photonic ionization of guanine bases and indirect formation of guanine radical cations through hole transfer reactions from other base radical cations. The formation of 8-oxo-7,8-dihydroguanine and other purine and pyrimidine degradation products was rationalized in terms of the initial generation of related radical cations followed by either hydration or deprotonation reactions in agreement with mechanistic pathways inferred from detailed mechanistic studies. The guanine radical cation has been shown to be implicated in three other nucleophilic additions that give rise to DNA-protein and DNA-DNA cross-links in model systems. Evidence was recently provided for the occurrence of these three reactions in cellular DNA. There is growing evidence that one-electron oxidation reactions of nucleobases whose mechanisms have been characterized in model studies involving aqueous solutions take place in a similar way in cells. It may also be pointed out that the above cross-linked lesions are only produced from the guanine radical cation and may be considered as diagnostic products of the direct effect of ionizing radiation.

  16. Evaluating Metabolite-Related DNA Oxidation and Adduct Damage from Aryl Amines Using a Microfluidic ECL Array.

    Bist, Itti; Bhakta, Snehasis; Jiang, Di; Keyes, Tia E; Martin, Aaron; Forster, Robert J; Rusling, James F

    2017-11-21

    Damage to DNA from the metabolites of drugs and pollutants constitutes a major human toxicity pathway known as genotoxicity. Metabolites can react with metal ions and NADPH to oxidize DNA or participate in S N 2 reactions to form covalently linked adducts with DNA bases. Guanines are the main DNA oxidation sites, and 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxodG) is the initial product. Here we describe a novel electrochemiluminescent (ECL) microwell array that produces metabolites from test compounds and measures relative rates of DNA oxidation and DNA adduct damage. In this new array, films of DNA, metabolic enzymes, and an ECL metallopolymer or complex assembled in microwells on a pyrolytic graphite wafer are housed in dual microfluidic chambers. As reactant solution passes over the wells, metabolites form and can react with DNA in the films to form DNA adducts. These adducts are detected by ECL from a RuPVP polymer that uses DNA as a coreactant. Aryl amines also combine with Cu 2+ and NADPH to form reactive oxygen species (ROS) that oxidize DNA. The resulting 8-oxodG was detected selectively by ECL-generating bis(2,2'-bipyridine)-(4-(1,10-phenanthrolin-6-yl)-benzoic acid)Os(II). DNA/enzyme films on magnetic beads were oxidized similarly, and 8-oxodG determined by LC/MS/MS enabled array standardization. The array limit of detection for oxidation was 720 8-oxodG per 10 6 nucleobases. For a series of aryl amines, metabolite-generated DNA oxidation and adduct formation turnover rates from the array correlated very well with rodent 1/TD 50 and Comet assay results.

  17. Efficiency of bimetallic PtPd on polydopamine modified on various carbon supports for alcohol oxidations

    Pinithchaisakula, A.; Ounnunkad, K.; Themsirimongkon, S.; Promsawan, N.; Waenkaew, P.; Saipanya, S.

    2017-02-01

    In this work, the preparation, characterization, and electrocatalytic analysis of the catalysts on various carbon substrates for direct alcohol fuel cells were studied. Selected carbons were modified with/without polydopamine (labelled as PDA-C and C) and further metal electrodeposited incorporated onto the glassy carbon (labelled as 5Pt1Pd/PDA-C and 5Pt1Pd/C). Four various carbon materials were used e.g. graphite (G), carbon nanotube (CNT), graphene (GP) and graphene oxide (GO) and the carbons were modified with PDA denoted as PDA-G, PDA-CNT, PDA-GP and PDA-GO, respectively. The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) experimental observation showed narrow size distribution of metal anchored on the PDA-C and C materials. Chemical compositions and oxidation states of the catalysts were determined by X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX). The catalytic performances for small organic electro-oxidation (e.g. methanol and ethanol) were measured by cyclic voltammetry (CV). Among different PDA-C and C catalysts, monometallic Pt showed less activity than the bimetallic catalysts. Among catalysts with PDA, the 5Pt1Pd/PDA-GO catalyst facilitated methanol and ethanol oxidations with high oxidation currents and If/Ib value and stability with low potentials while among catalysts without PDA, the 5Pt1Pd/CNT provides highest activity and stability. It was found that the catalysts with PDA provided high activity and stability than the catalysts without PDA. The improved catalytic performance of the prepared catalysts could be related to the higher active surface area from polymer modification and bimetallic catalyst system in the catalyst composites.

  18. Two-Sided Surface Oxidized Cellulose Membranes Modified with PEI: Preparation, Characterization and Application for Dyes Removal

    Wei Wang

    2017-09-01

    Full Text Available Porous regenerated cellulose (RC membranes were prepared with cotton linter pulp as a raw material. These membranes were first oxidized on both sides by a modified (2,2,6,6-tetramethylpiperidin-1-yloxyl (TEMPO oxidation system using a controlled oxidation reaction technique. Then, the oxidized RC membranes were functionalized with polyethylenimine (PEI via the glutaraldehyde crosslinking method to obtain bifunctional (carboxyl and amino porous RC membranes, as revealed by Fourier transform infrared spectroscopy (FT-IR, elemental analysis and zeta potential measurement. The scanning electron microscopy (SEM and the tests of the mechanical properties and permeability characteristics of modified RC membranes demonstrated that the porous structure and certain mechanical properties could be retained. The adsorption performance of the modified membranes towards dyes was subsequently investigated. The modified membranes displayed good adsorption capacities, rapid adsorption equilibrium and removal efficiencies towards both anionic (xylenol orange (XO and cationic (methylene blue (MB dyes, making them suitable bioadsorbents for wastewater treatment.

  19. The effect of obstructive sleep apnea on DNA damage and oxidative stress.

    Kang, Il Gyu; Jung, Joo Hyun; Kim, Seon Tae

    2013-06-01

    Obstructive sleep apnea syndrome (OSAS) is associated with repeated hypoxia and re-oxygenation. This characteristic of OSAS may cause oxidative stress and DNA damage. However, the link of OSAS with oxidative stress and DNA damage is still controversial. In the current study, we investigated whether OSAS causes DNA damage using alkaline single-cell gel electrophoresis (comet assay) and measuring oxidative stress by monitoring serum malondialdehyde (MDA) levels. From March 2009 to August 2010, 51 patients who underwent polysomnography (PSG) during the night were enrolled in this study. We obtained serum from the patients at 6 AM. DNA damage and oxidative stress were evaluated using a comet assay and measuring serum MDA, respectively. We divided the patients into two groups according to the existence of comets appearing in the comet assay. Group 1 included 44 patients with negative assay results and group 2 consisted of seven patients with positive comet assay findings. We compared the age, gender proportion, PSG data (respiratory disturbance index [RDI], lowest O2 saturation level, and arousal index [AI]), time of disease onset, smoking habits, and serum MDA levels between the two groups. The average age and gender proportion of the two groups were not statistically different (P>0.05). The average of RDI for group 1 was 30.4±18.4 and 8.0±7.7 (P0.05). No relationship between positive comet assay results and OSAS severity was identified. Results of the current study showed that OSAS was not associated with DNA damage as measured by comet assays or oxidative stress according to serum MDA levels.

  20. Ionic liquid-modified metal sulfides/graphene oxide nanocomposites for photoelectric conversion

    Zhang, Yu; Zhang, Yù; Pei, Qi; Feng, Ting; Mao, Hui; Zhang, Wei; Wu, Shuyao; Liu, Daliang; Wang, Hongyu; Song, Xi-Ming

    2015-01-01

    Graphical abstract: - Highlights: • Metal sulfide (CdS, ZnS, Ag 2 S)/GO nanocomposites were prepared by electrostatic adherence. • Ionic liquid was used to link the metal sulfide and GO in the electrostatic adherence process. • The as-prepared samples showed enhanced photocurrent and highly efficient photocatalytic activity under visible light irradiation. - Abstract: Ionic liquid-modified metal sulfides/graphene oxide nanocomposites are prepared via a facile electrostatic adsorption. Ionic liquid (IL) is firstly used as surface modifier and structure-directing agent of metal sulfide (MS) crystallization process, obtaining ionic liquid modified-MS (IL-MS) nanoparticles with positive charges on surface. IL-MS/GO is obtained by electrostatic adherence between positively charged IL-MS and negatively charged graphene oxide (GO). The as-prepared sample shows enhanced photocurrent and highly efficient photocatalytic activity under visible light irradiation, indicating IL-MS/GO nanocomposites greatly promoted the separation of photogenerated electron–hole pairs

  1. Active Bilayer PE/PCL Films for Food Packaging Modified with Zinc Oxide and Casein

    Ana Rešček

    2015-12-01

    Full Text Available This paper studies the properties of active polymer food packaging bilayer polyethylene/polycaprolactone (PE/PCL films. Such packaging material consists of primary PE layer coated with thin film of PCL coating modified with active component (zinc oxide or zinc oxide/casein complex with intention to extend the shelf life of food and to maintain the quality and health safety. The influence of additives as active components on barrier, mechanical, thermal and antimicrobial properties of such materials was studied. The results show that, in comparison to the neat PE and PE/PCL films, some of PE/PCL bilayer films with additives exhibit improved barrier properties i.e. decreased water vapour permeability. Higher thermal stability of modified PE/PCL material is obtained due to a modified mechanism of thermal degradation. The samples with the additive nanoparticles homogeneously dispersed in the polymer matrix showed good mechanical properties. Addition of higher ZnO content contributes to the enhanced antibacterial activity of a material.

  2. Anchoring of self-assembled plasmid DNA/ anti-DNA antibody/cationic lipid micelles on bisphosphonate-modified stent for cardiovascular gene delivery

    Ma G

    2013-03-01

    Full Text Available Guilei Ma,1,# Yong Wang,1,# Ilia Fishbein,2 Mei Yu,1 Linhua Zhang,1 Ivan S Alferiev,2 Jing Yang,1 Cunxian Song,1 Robert J Levy2 1Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, People's Republic of China; 2Children's Hospital of Philadelphia, Abramson Research Building, Philadelphia, PA, USA #These authors contributed equally to this work Purpose: To investigate the anchoring of plasmid DNA/anti-DNA antibody/cationic lipid tri-complex (DAC micelles onto bisphosphonate-modified 316 L coronary stents for cardiovascular site-specific gene delivery. Methods: Stents were first modified with polyallylamine bisphosphonate (PAA-BP, thereby enabling the retention of a PAA-BP molecular monolayer that permits the anchoring (via vector-binding molecules of DAC micelles. DAC micelles were then chemically linked onto the PAA-BP-modified stents by using N-succinimidyl-3-(2-pyridyldithiol-propionate (SPDP as a crosslinker. Rhodamine-labeled DNA was used to assess the anchoring of DAC micelles, and radioactive-labeled antibody was used to evaluate binding capacity and stability. DAC micelles (encoding green fluorescent protein were tethered onto the PAA-BP-modified stents, which were assessed in cell culture. The presence of a PAA-BP molecular monolayer on the steel surface was confirmed by X-ray photoelectron spectroscopy and atomic force microscope analysis. Results: The anchoring of DAC micelles was generally uniform and devoid of large-scale patches of defects. Isotopic quantification confirmed that the amount of antibody chemically linked on the stents was 17-fold higher than that of the physical adsorbed control stents and its retention time was also significantly longer. In cell culture, numerous green fluorescent protein-positive cells were found on the PAA-BP modified stents, which demonstrated high localization and efficiency of gene delivery. Conclusion: The DAC micelle

  3. Elevated levels of urinary markers of oxidatively generated DNA and RNA damage in bipolar disorder

    Munkholm, Klaus; Poulsen, Henrik Enghusen; Kessing, Lars Vedel

    2015-01-01

    OBJECTIVES: The pathophysiological mechanisms underlying bipolar disorder and its multi-system nature are unclear. Oxidatively generated damage to nucleosides has been demonstrated in metabolic disorders; however, the extent to which this occurs in bipolar disorder in vivo is unknown. We...... investigated oxidatively generated damage to DNA and RNA in patients with bipolar disorder and its relationship with the affective phase compared with healthy control subjects. METHODS: Urinary excretion of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo), markers...... of oxidatively generated DNA and RNA damage, respectively, was measured in 37 rapid cycling patients with bipolar disorder and in 40 age- and gender-matched healthy control subjects. Employing a longitudinal design, repeated measurements of both markers were evaluated in various affective phases in patients...

  4. Association between Urinary Excretion of Cortisol and Markers of Oxidatively Damaged DNA and RNA in Humans

    Joergensen, Anders; Broedbaek, Kasper; Weimann, Allan

    2011-01-01

    Chronic psychological stress is associated with accelerated aging, but the underlying biological mechanisms are not known. Prolonged elevations of the stress hormone cortisol is suspected to play a critical role. Through its actions, cortisol may potentially induce oxidatively generated damage...... to cellular constituents such as DNA and RNA, a phenomenon which has been implicated in aging processes. We investigated the relationship between 24 h excretion of urinary cortisol and markers of oxidatively generated DNA and RNA damage, 8-oxo-7,8-dihydro-2'-deoxyguanosine and 8-oxo-7,8-dihydroguanosine......, in a sample of 220 elderly men and women (age 65 - 83 years). We found a robust association between the excretion of cortisol and the oxidation markers (R(2)¿=¿0.15, P...

  5. Transgenerational inheritance of modified DNA methylation patterns and enhanced tolerance induced by heavy metal stress in rice (Oryza sativa L.).

    Ou, Xiufang; Zhang, Yunhong; Xu, Chunming; Lin, Xiuyun; Zang, Qi; Zhuang, Tingting; Jiang, Lili; von Wettstein, Diter; Liu, Bao

    2012-01-01

    DNA methylation is sensitive and responsive to stressful environmental conditions. Nonetheless, the extent to which condition-induced somatic methylation modifications can impose transgenerational effects remains to be fully understood. Even less is known about the biological relevance of the induced epigenetic changes for potentially altered well-being of the organismal progenies regarding adaptation to the specific condition their progenitors experienced. We analyzed DNA methylation pattern by gel-blotting at genomic loci representing transposable elements and protein-coding genes in leaf-tissue of heavy metal-treated rice (Oryza sativa) plants (S0), and its three successive organismal generations. We assessed expression of putative genes involved in establishing and/or maintaining DNA methylation patterns by reverse transcription (RT)-PCR. We measured growth of the stressed plants and their unstressed progenies vs. the control plants. We found (1) relative to control, DNA methylation patterns were modified in leaf-tissue of the immediately treated plants, and the modifications were exclusively confined to CHG hypomethylation; (2) the CHG-demethylated states were heritable via both maternal and paternal germline, albeit often accompanying further hypomethylation; (3) altered expression of genes encoding for DNA methyltransferases, DNA glycosylase and SWI/SNF chromatin remodeling factor (DDM1) were induced by the stress; (4) progenies of the stressed plants exhibited enhanced tolerance to the same stress their progenitor experienced, and this transgenerational inheritance of the effect of condition accompanying heritability of modified methylation patterns. Our findings suggest that stressful environmental condition can produce transgenerational epigenetic modifications. Progenies of stressed plants may develop enhanced adaptability to the condition, and this acquired trait is inheritable and accord with transmission of the epigenetic modifications. We suggest

  6. Electrochemical oxidation of pulp and paper making wastewater assisted by transition metal modified kaolin

    Wang Bo; Gu Lin; Ma Hongzhu

    2007-01-01

    The electrochemical oxidation of pulp and paper making wastewater assisted by transition metal (Co, Cu) modified kaolin in a 200 ml electrolytic batch reactor with graphite plate as electrodes was investigated. H 2 O 2 , which produced on the surface of porous graphite cathode, would react with the catalysts to form strong oxidant (hydroxyl radicals) that can in turn destruct the pollutants adsorbed on the surface of kaolin. The transition metal (Co, Cu) modified kaolin was also characterized by XRD and SEM before and after the modification and the results showed that the transition metals were completely supported on kaolin and formed a porous structure with big BET surface. The mechanism was proposed on the basis of XPS analysis of the catalyst after the degradation process. Series of experiments were also done to prove the synergetic effect of the combined oxidation system and to find out the optimal operating parameters such as initial pH, current density and amount of catalyst. From the results it can be founded that when the initial pH was at 3, current density was 30 mA cm -2 ; catalyst dose was 30 g dm -3 , COD (chemical oxygen demand) removal could reach up to 96.8% in 73 min

  7. Improvement of the stability and activity of immobilized glucose oxidase on modified iron oxide magnetic nanoparticles

    Abbasi, Mahboube, E-mail: mahbubeabbasi@yahoo.com; Amiri, Razieh, E-mail: razieh.amiri@gmail.com; Bordbar, Abdol-Kalegh, E-mail: bordbar@chem.ui.ac.ir; Ranjbakhsh, Elnaz, E-mail: e.ranjbakhsh@yahoo.com; Khosropour, Ahmad-Reza, E-mail: khosropour@chem.ui.ac.ir

    2016-02-28

    Graphical abstract: - Highlights: • Modified iron oxide magnetic nanoparticles were synthesized by co-precipitation method and characterized by TEM and XRD. • Covalent attachment of GOX to MIMNs was confirmed by FT-IR technique. • Optimization of the reaction time and initial amount of the GOX were carried out. • Improvement of activity and stability of immobilized GOX have been increased in comparison of free GOX. - Abstract: Immobilized proteins and enzymes are widely investigated in the medical field as well as the food and environmental fields. In this study, glucose oxidase (GOX) was covalently immobilized on the surface of modified iron oxide magnetic nanoparticles (MIMNs) to produce a bioconjugate complex. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to the size, shape and structure characterization of the MIMNs. Binding of GOX to these MIMNs was confirmed by using FT-IR spectroscopy. The stability of the immobilized and free enzyme at different temperature and pH values was investigated by measuring the enzymatic activity. These studies reveal that the enzyme's stability is enhanced by immobilization. Further experiments showed that the storage stability of the enzyme is improved upon binding to the MIMNs. The results of kinetic measurements suggest that the effect of the immobilization process on substrate and product diffusion is small. Such bioconjugates can be considered as a catalytic nanodevice for accelerating the glucose oxidation reaction for biotechnological purposes.

  8. Determination of thymine glycol residues in irradiated or oxidized DNA by formation of methylglyceric acid

    Schellenberg, K.A.; Shaeffer, J.

    1986-01-01

    Treatment of DNA solutions with X-irradiation various oxidants including hydrogen peroxide plus ferrous ion, hydrogen peroxide plus copper ion and ascorbate, permanganate, or sonication in the presence of dissolved oxygen all produced varying amounts of thymine glycol residues. After denaturing the DNA with heat, the glycol residues were reduced and labeled at the 6 position with tritium- labeled sodium borohydride. Subsequent reaction with anhydrous methanolic HCl gave a quantitative yield of the methyl ester of methylglyceric acid, which was determined by thin layer chromatography. The method, developed using thymidine as a model, was used to ascertain the requirements for glycol formation in DNA. It was shown that hydroxyl radical generating systems, permanganate, X-irradiation, or sonication in presence of oxygen were required, but hydrogen peroxide in the absence of iron or copper and ascorbate was inactive. Application to determination of DNA damage in vivo is being explored

  9. DNA-decorated carbon-nanotube-based chemical sensors on complementary metal oxide semiconductor circuitry

    Chen, Chia-Ling; Yang, Chih-Feng; Dokmeci, Mehmet R; Agarwal, Vinay; Sonkusale, Sameer; Kim, Taehoon; Busnaina, Ahmed; Chen, Michelle

    2010-01-01

    We present integration of single-stranded DNA (ss-DNA)-decorated single-walled carbon nanotubes (SWNTs) onto complementary metal oxide semiconductor (CMOS) circuitry as nanoscale chemical sensors. SWNTs were assembled onto CMOS circuitry via a low voltage dielectrophoretic (DEP) process. Besides, bare SWNTs are reported to be sensitive to various chemicals, and functionalization of SWNTs with biomolecular complexes further enhances the sensing specificity and sensitivity. After decorating ss-DNA on SWNTs, we have found that the sensing response of the gas sensor was enhanced (up to ∼ 300% and ∼ 250% for methanol vapor and isopropanol alcohol vapor, respectively) compared with bare SWNTs. The SWNTs coupled with ss-DNA and their integration on CMOS circuitry demonstrates a step towards realizing ultra-sensitive electronic nose applications.

  10. Effects of trimethylamine N-oxide and urea on DNA duplex and G-quadruplex.

    Ueda, Yu-Mi; Zouzumi, Yu-Ki; Maruyama, Atsushi; Nakano, Shu-Ichi; Sugimoto, Naoki; Miyoshi, Daisuke

    2016-01-01

    We systematically investigated effects of molecular crowding with trimethylamine N -oxide (TMAO) as a zwitterionic and protective osmolyte and urea as a nonionic denaturing osmolyte on conformation and thermodynamics of the canonical DNA duplex and the non-canonical DNA G-quadruplex. It was found that TMAO and urea stabilized and destabilized, respectively, the G-quadruplex. On the other hand, these osmolytes generally destabilize the duplex; however, it was observed that osmolytes having the trimethylamine group stabilized the duplex at the lower concentrations because of a direct binding to a groove of the duplex. These results are useful not only to predict DNA structures and their thermodynamics under physiological environments in living cells, but also design of polymers and materials to regulate structure and stability of DNA sequences.

  11. Tail-labelling of DNA probes using modified deoxynucleotide triphosphates and terminal deoxynucleotidyl tranferase. Application in electrochemical DNA hybridization and protein-DNA binding assays

    Horáková Brázdilová, Petra; Macíčková-Cahová, Hana; Pivoňková, Hana; Špaček, Jan; Havran, Luděk; Hocek, Michal; Fojta, Miroslav

    2011-01-01

    Roč. 9, č. 5 (2011), s. 1366-1371 ISSN 1477-0520 R&D Projects: GA MŠk(CZ) LC06035; GA MŠk(CZ) LC512; GA AV ČR(CZ) IAA400040901 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702; CEZ:AV0Z40550506 Keywords : DNA tail- labelling * protein-DNA binding * DNA hybridization Subject RIV: BO - Biophysics Impact factor: 3.696, year: 2011

  12. Understanding DNA Under Oxidative Stress and Sensitization: The Role of Molecular Modeling

    Antonio eMonari

    2015-07-01

    Full Text Available DNA is constantly exposed to damaging threats coming from oxidative stress, i.e. from the presence of free radicals and reactive oxygen species. Sensitization from exogenous and endogenous compounds that strongly enhance the frequency of light-induced lesions also plays an important role. The experimental determination of DNA lesions, though a difficult subject, is somehow well established and allows to elucidate even extremely rare DNA lesions. In parallel, molecular modeling has become fundamental to clearly understand the fine mechanisms related to DNA defects induction. Indeed, it offers an unprecedented possibility to get access to an atomistic or even electronic resolution. Ab initio molecular dynamics may also describe the time-evolution of the molecular system and its reactivity. Yet the modeling of DNA (photo-reactions does necessitate elaborate multi-scale methodologies to tackle a damage induction reactivity that takes place in a complex environment. The double-stranded DNA environment is first characterized by a very high flexibility, that dynamical effects are to be taken into account, but also a strongly inhomogeneous electrostatic embedding. Additionally, one aims at capturing more subtle effects, such as the sequence selectivity which is of critical important for DNA damage. The structure and dynamics of the DNA/sensitizers complexes, as well as the photo-induced electron- and energy-transfer phenomena taking place upon sensitization, should be carefully modeled. Finally the factors inducing different repair ratios for different lesions should also be rationalized.In this review we will critically analyze the different computational strategies used to model DNA lesions. A clear picture of the complex interplay between reactivity and structural factors will be sketched. The use of proper multi-scale modeling leads to the in-depth comprehension of DNA lesions mechanism and also to the rational design of new chemo-therapeutic agents.

  13. The effect of long-term oxidation on the rheological properties of polymer modified asphalts

    Yonghong Ruan; Richard R. Davison; Charles J. Glover [Texas A & M University, College Station, TX (United States). Department of Chemical Engineering

    2003-10-01

    The effect of long-term aging on rheological properties of polymer modified asphalt binders was studied. Modifiers included diblock poly(styrene-b-butadiene) rubber, triblock poly(styrene-b-butadiene-b-styrene), and tire rubber. Asphalt aging was carried out either at 60{sup o}C in a controlled environmental room or at 100{sup o}C in a pressure aging vessel (AASHTO Provisional Standards, 1993). Both dynamic shear properties and extensional properties were investigated. Polymer modification resulted in increased asphalt complex modulus at high temperatures, decreased asphalt complex modulus at low temperatures, broadened relaxation spectra, and improved ductility. Oxidative aging decreased asphalt temperature susceptibility, damaged the polymer network in binders, further broadened the relaxation spectrum, and diminished polymer effectiveness in improving asphalt ductility. 27 refs., 8 figs., 3 tabs.

  14. Preparation of Phosphonic Acid Functionalized Graphene Oxide-modified Aluminum Powder with Enhanced Anticorrosive Properties

    He, Lihua; Zhao, Yan; Xing, Liying; Liu, Pinggui; Wang, Zhiyong; Zhang, Youwei; Liu, Xiaofang

    2017-07-01

    To improve the anticorrosive performance of aluminum powder, a common functional filler in polymer coatings, we report a novel method to prepare graphene oxide modified aluminum powder (GO-Al) using 3-aminoproplyphosphoic acid as "link" agent. The GO nanosheets were firstly functionalized with 3-aminoproplyphosphoic acid (APSA) by the reaction of amine groups of APSA and the epoxy groups of GO. Subsequently, a layer of GO nanosheets uniformly and tightly covered the surface of flaky aluminum particle though the strong linking strength between -PO(OH)2 functional groups of the modified GO and aluminum. The hydrogen evolution experiment suggests that the GO attached on the aluminum powder could effectively improve the anticorrosive performance of the pigments.

  15. Effective Electrochemistry of Human Sulfite Oxidase Immobilized on Quantum-Dots-Modified Indium Tin Oxide Electrode.

    Zeng, Ting; Leimkühler, Silke; Koetz, Joachim; Wollenberger, Ulla

    2015-09-30

    The bioelectrocatalytic sulfite oxidation by human sulfite oxidase (hSO) on indium tin oxide (ITO) is reported, which is facilitated by functionalizing of the electrode surface with polyethylenimine (PEI)-entrapped CdS nanoparticles and enzyme. hSO was assembled onto the electrode with a high surface loading of electroactive enzyme. In the presence of sulfite but without additional mediators, a high bioelectrocatalytic current was generated. Reference experiments with only PEI showed direct electron transfer and catalytic activity of hSO, but these were less pronounced. The application of the polyelectrolyte-entrapped quantum dots (QDs) on ITO electrodes provides a compatible surface for enzyme binding with promotion of electron transfer. Variations of the buffer solution conditions, e.g., ionic strength, pH, viscosity, and the effect of oxygen, were studied in order to understand intramolecular and heterogeneous electron transfer from hSO to the electrode. The results are consistent with a model derived for the enzyme by using flash photolysis in solution and spectroelectrochemistry and molecular dynamic simulations of hSO on monolayer-modified gold electrodes. Moreover, for the first time a photoelectrochemical electrode involving immobilized hSO is demonstrated where photoexcitation of the CdS/hSO-modified electrode lead to an enhanced generation of bioelectrocatalytic currents upon sulfite addition. Oxidation starts already at the redox potential of the electron transfer domain of hSO and is greatly increased by application of a small overpotential to the CdS/hSO-modified ITO.

  16. Highly Sensitive DNA Sensor Based on Upconversion Nanoparticles and Graphene Oxide.

    Alonso-Cristobal, P; Vilela, P; El-Sagheer, A; Lopez-Cabarcos, E; Brown, T; Muskens, O L; Rubio-Retama, J; Kanaras, A G

    2015-06-17

    In this work we demonstrate a DNA biosensor based on fluorescence resonance energy transfer (FRET) between NaYF4:Yb,Er nanoparticles and graphene oxide (GO). Monodisperse NaYF4:Yb,Er nanoparticles with a mean diameter of 29.1 ± 2.2 nm were synthesized and coated with a SiO2 shell of 11 nm, which allowed the attachment of single strands of DNA. When these DNA-functionalized NaYF4:Yb,Er@SiO2 nanoparticles were in the proximity of the GO surface, the π-π stacking interaction between the nucleobases of the DNA and the sp(2) carbons of the GO induced a FRET fluorescence quenching due to the overlap of the fluorescence emission of the NaYF4:Yb,Er@SiO2 and the absorption spectrum of GO. By contrast, in the presence of the complementary DNA strands, the hybridization leads to double-stranded DNA that does not interact with the GO surface, and thus the NaYF4:Yb,Er@SiO2 nanoparticles remain unquenched and fluorescent. The high sensitivity and specificity of this sensor introduces a new method for the detection of DNA with a detection limit of 5 pM.

  17. Oxidative DNA Damage in Neurons: Implication of Ku in Neuronal Homeostasis and Survival

    Daniela De Zio

    2012-01-01

    Full Text Available Oxidative DNA damage is produced by reactive oxygen species (ROS which are generated by exogenous and endogenous sources and continuously challenge the cell. One of the most severe DNA lesions is the double-strand break (DSB, which is mainly repaired by nonhomologous end joining (NHEJ pathway in mammals. NHEJ directly joins the broken ends, without using the homologous template. Ku70/86 heterodimer, also known as Ku, is the first component of NHEJ as it directly binds DNA and recruits other NHEJ factors to promote the repair of the broken ends. Neurons are particularly metabolically active, displaying high rates of transcription and translation, which are associated with high metabolic and mitochondrial activity as well as oxygen consumption. In such a way, excessive oxygen radicals can be generated and constantly attack DNA, thereby producing several lesions. This condition, together with defective DNA repair systems, can lead to a high accumulation of DNA damage resulting in neurodegenerative processes and defects in neurodevelopment. In light of recent findings, in this paper, we will discuss the possible implication of Ku in neurodevelopment and in mediating the DNA repair dysfunction observed in certain neurodegenerations.

  18. Accumulation of premutagenic DNA lesions in mice defective in removal of oxidative base damage

    Klungland, Arne; Rosewell, Ian; Hollenbach, Stephan; Larsen, Elisabeth; Daly, Graham; Epe, Bernd; Seeberg, Erling; Lindahl, Tomas; Barnes, Deborah E.

    1999-01-01

    DNA damage generated by oxidant byproducts of cellular metabolism has been proposed as a key factor in cancer and aging. Oxygen free radicals cause predominantly base damage in DNA, and the most frequent mutagenic base lesion is 7,8-dihydro-8-oxoguanine (8-oxoG). This altered base can pair with A as well as C residues, leading to a greatly increased frequency of spontaneous G·C→T·A transversion mutations in repair-deficient bacterial and yeast cells. Eukaryotic cells use a specific DNA glycosylase, the product of the OGG1 gene, to excise 8-oxoG from DNA. To assess the role of the mammalian enzyme in repair of DNA damage and prevention of carcinogenesis, we have generated homozygous ogg1−/− null mice. These animals are viable but accumulate abnormal levels of 8-oxoG in their genomes. Despite this increase in potentially miscoding DNA lesions, OGG1-deficient mice exhibit only a moderately, but significantly, elevated spontaneous mutation rate in nonproliferative tissues, do not develop malignancies, and show no marked pathological changes. Extracts of ogg1 null mouse tissues cannot excise the damaged base, but there is significant slow removal in vivo from proliferating cells. These findings suggest that in the absence of the DNA glycosylase, and in apparent contrast to bacterial and yeast cells, an alternative repair pathway functions to minimize the effects of an increased load of 8-oxoG in the genome and maintain a low endogenous mutation frequency. PMID:10557315

  19. Methanol electro-oxidation on platinum modified tungsten carbides in direct methanol fuel cells: a DFT study.

    Sheng, Tian; Lin, Xiao; Chen, Zhao-Yang; Hu, P; Sun, Shi-Gang; Chu, You-Qun; Ma, Chun-An; Lin, Wen-Feng

    2015-10-14

    In exploration of low-cost electrocatalysts for direct methanol fuel cells (DMFCs), Pt modified tungsten carbide (WC) materials are found to be great potential candidates for decreasing Pt usage whilst exhibiting satisfactory reactivity. In this work, the mechanisms, onset potentials and activity for electrooxidation of methanol were studied on a series of Pt-modified WC catalysts where the bare W-terminated WC(0001) substrate was employed. In the surface energy calculations of a series of Pt-modified WC models, we found that the feasible structures are mono- and bi-layer Pt-modified WCs. The tri-layer Pt-modified WC model is not thermodynamically stable where the top layer Pt atoms tend to accumulate and form particles or clusters rather than being dispersed as a layer. We further calculated the mechanisms of methanol oxidation on the feasible models via methanol dehydrogenation to CO involving C-H and O-H bonds dissociating subsequently, and further CO oxidation with the C-O bond association. The onset potentials for the oxidation reactions over the Pt-modified WC catalysts were determined thermodynamically by water dissociation to surface OH* species. The activities of these Pt-modified WC catalysts were estimated from the calculated kinetic data. It has been found that the bi-layer Pt-modified WC catalysts may provide a good reactivity and an onset oxidation potential comparable to pure Pt and serve as promising electrocatalysts for DMFCs with a significant decrease in Pt usage.

  20. Oral contraceptives modify DNA methylation and monocyte-derived macrophage function

    Campesi Ilaria

    2012-01-01

    were lower in FOCA- than in FOCA+. Importantly, FOCs had a lower global DNA methylation, indicating that OC may have epigenetic effects on gene expression. OC did not modify the expression of androgen receptor but increased estrogen receptor α expression, more considerably in FOCA+, and decreased estrogen receptor β, more considerably in FOCA-. Importantly, the activation state of estrogen receptor β in FOCs was decreased, while estrogen receptor α was not active in either Fs or FOCs. Unstimulated MDMs obtained from FOCs showed higher release of TNFα in comparison with Fs. After lipopolysaccharide stimulation, the release of TNFα was significantly higher in Fs than in FOCs. Conclusions OC use induced many changes in hematological and plasmatic markers, modifying hormonal levels, endothelial function, inflammation index and some redox state parameters, producing a perturbation of the internal milieu that impacted macrophagic function. In fact, different levels of estrogen receptor expression and release of TNFα were observed in macrophages derived from OC users. Some of the above activities were linked to the androgenic properties of progestin. Even though it is not known whether these effects are reversible, the results indicate that to avoid potential skewing of results only a single type of OC should be used during a single clinical trial.

  1. Age-dependent oxidative stress-induced DNA damage in Down's lymphocytes

    Zana, Marianna; Szecsenyi, Anita; Czibula, Agnes; Bjelik, Annamaria; Juhasz, Anna; Rimanoczy, Agnes; Szabo, Krisztina; Vetro, Agnes; Szucs, Peter; Varkonyi, Agnes; Pakaski, Magdolna; Boda, Krisztina; Rasko, Istvan; Janka, Zoltan; Kalman, Janos

    2006-01-01

    The aim of the present study was to investigate the oxidative status of lymphocytes from children (n = 7) and adults (n = 18) with Down's syndrome (DS). The basal oxidative condition, the vulnerability to in vitro hydrogen peroxide exposure, and the repair capacity were measured by means of the damage-specific alkaline comet assay. Significantly and age-independently elevated numbers of single strand breaks and oxidized bases (pyrimidines and purines) were found in the nuclear DNA of the lymphocytes in the DS group in the basal condition. These results may support the role of an increased level of endogenous oxidative stress in DS and are similar to those previously demonstrated in Alzheimer's disease. In the in vitro oxidative stress-induced state, a markedly higher extent of DNA damage was observed in DS children as compared with age- and gender-matched healthy controls, suggesting that young trisomic lymphocytes are more sensitive to oxidative stress than normal ones. However, the repair ability itself was not found to be deteriorated in either DS children or DS adults

  2. Formic Acid Modified Co3O4-CeO2 Catalysts for CO Oxidation

    Ruishu Shang

    2016-03-01

    Full Text Available A formic acid modified catalyst, Co3O4-CeO2, was prepared via facile urea-hydrothermal method and applied in CO oxidation. The Co3O4-CeO2-0.5 catalyst, treated by formic acid at 0.5 mol/L, performed better in CO oxidation with T50 obtained at 69.5 °C and T100 obtained at 150 °C, respectively. The characterization results indicate that after treating with formic acid, there is a more porous structure within the Co3O4-CeO2 catalyst; meanwhile, despite of the slightly decreased content of Co, there are more adsorption sites exposed by acid treatment, as suggested by CO-TPD and H2-TPD, which explains the improvement of catalytic performance.

  3. Voltammetric sensor for caffeine based on a glassy carbon electrode modified with Nafion and graphene oxide

    Zhao, F.; Wang, F.; Zhao, W.; Zhou, J.; Liu, Y.; Zou, L.; Ye, B.

    2011-01-01

    We report on a voltammetric sensor for caffeine that is based on a glassy carbon electrode modified with Nafion and graphene oxide (GO). It exhibits a good affinity for caffeine (resulting from the presence of Nafion), and excellent electrochemical response (resulting from the pressence of GO) for the oxidation of caffeine. The electrode enables the determination of caffeine in the range from 4.0 x 10 -7 to 8.0 x 10 -5 mol L -1 , with a detection limit of 2.0 x 10 -7 mol L -1 . The sensor displays good stability, reproducibility, and high sensitivity. It was successfully applied to the quantitative determination of caffeine in beverages. (author)

  4. Adhesion mapping of chemically modified and poly(ethylene oxide)-grafted glass surfaces

    Jogikalmath, G.; Stuart, J.K.; Pungor, A.; Hlady, V.

    1999-01-01

    Two-dimensional mapping of the adhesion pull-off forces was used to study the origin of surface heterogeneity in the grafted poly(ethylene oxide) (PEO) layer. The variance of the pull-off forces measured over the μm-sized regions after each chemical step of modifying glass surfaces was taken to be a measure of the surface chemical heterogeneity. The attachment of γ-glycidoxypropyltrimethoxy silane (GPS) to glass decreased the pull-off forces relative to the clean glass and made the surface mo...

  5. Carnosine attenuates cyclophosphamide-induced bone marrow suppression by reducing oxidative DNA damage

    Jie Deng

    2018-04-01

    Full Text Available Oxidative DNA damage in bone marrow cells is the main side effect of chemotherapy drugs including cyclophosphamide (CTX. However, not all antioxidants are effective in inhibiting oxidative DNA damage. In this study, we report the beneficial effect of carnosine (β-alanyl-l-histidine, a special antioxidant with acrolein-sequestering ability, on CTX-induced bone marrow cell suppression. Our results show that carnosine treatment (100 and 200 mg/kg, i.p. significantly inhibited the generation of reactive oxygen species (ROS and 8-hydroxy-2′-deoxyguanosine (8-oxo-dG, and decreased chromosomal abnormalities in the bone marrow cells of mice treated with CTX (20 mg/kg, i.v., 24 h. Furthermore, carnosine evidently mitigated CTX-induced G2/M arrest in murine bone marrow cells, accompanied by reduced ratios of p-Chk1/Chk1 and p-p53/p53 as well as decreased p21 expression. In addition, cell apoptosis caused by CTX was also suppressed by carnosine treatment, as assessed by decreased TUNEL-positive cell counts, down-regulated expressions of Bax and Cyt c, and reduced ratios of cleaved Caspase-3/Caspase-3. These results together suggest that carnosine can protect murine bone marrow cells from CTX-induced DNA damage via its antioxidant activity. Keywords: Carnosine, Cyclophosphamide, Oxidative DNA damage, Sister chromatid exchange, Apoptosis, Cell cycle arrest

  6. Stable Water Oxidation in Acid Using Manganese-Modified TiO2 Protective Coatings.

    Siddiqi, Georges; Luo, Zhenya; Xie, Yujun; Pan, Zhenhua; Zhu, Qianhong; Röhr, Jason A; Cha, Judy J; Hu, Shu

    2018-06-06

    Accomplishing acid-stable water oxidation is a critical matter for achieving both long-lasting water-splitting devices and other fuel-forming electro- and photocatalytic processes. Because water oxidation releases protons into the local electrolytic environment, it becomes increasingly acidic during device operation, which leads to corrosion of the photoactive component and hence loss in device performance and lifetime. In this work, we show that thin films of manganese-modified titania, (Ti,Mn)O x , topped with an iridium catalyst, can be used in a coating stabilization scheme for acid-stable water oxidation. We achieved a device lifetime of more than 100 h in pH = 0 acid. We successfully grew (Ti,Mn)O x coatings with uniform elemental distributions over a wide range of manganese compositions using atomic layer deposition (ALD), and using X-ray photoelectron spectroscopy, we show that (Ti,Mn)O x films grown in this manner give rise to closer-to-valence-band Fermi levels, which can be further tuned with annealing. In contrast to the normally n-type or intrinsic TiO 2 coatings, annealed (Ti,Mn)O x films can make direct charge transfer to a Fe(CN) 6 3-/4- redox couple dissolved in aqueous electrolytes. Using the Fe(CN) 6 3-/4- redox, we further demonstrated anodic charge transfer through the (Ti,Mn)O x films to high work function metals, such as iridium and gold, which is not previously possible with ALD-grown TiO 2 . We correlated changes in the crystallinity (amorphous to rutile TiO 2 ) and oxidation state (2+ to 3+) of the annealed (Ti,Mn)O x films to their hole conductivity and electrochemical stability in acid. Finally, by combining (Ti,Mn)O x coatings with iridium, an acid-stable water-oxidation anode, using acid-sensitive conductive fluorine-doped tin oxides, was achieved.

  7. Electrochemical and morphological analyses on the titanium surface modified by shot blasting and anodic oxidation processes

    Szesz, Eduardo M., E-mail: eszesz@neoortho.com.br [Neoortho Research Institute, Rua Ângelo Domingos Durigan, 607-Cascatinha, CEP 82025-100 Curitiba, PR (Brazil); Pereira, Bruno L., E-mail: brnl7@hotmail.com [Physics Department, Universidade Federal do Paraná, 81531-980 Curitiba, PR (Brazil); Kuromoto, Neide K., E-mail: kuromoto@fisica.ufpr.br [Physics Department, Universidade Federal do Paraná, 81531-980 Curitiba, PR (Brazil); Marino, Claudia E.B., E-mail: claudiamarino@yahoo.com [Mechanical Engineering Department, Universidade Federal do Paraná, 81531-980 Curitiba, PR (Brazil); Souza, Gelson B. de, E-mail: gelsonbs@uepg.br [Physics Department, Universidade Estadual de Ponta Grossa, 84051-510 Ponta Grossa, PR (Brazil); Soares, Paulo, E-mail: pa.soares@pucpr.br [Mechanical Engineering Department, Pontifícia Universidade Católica do Paraná, 80215-901 Curitiba, PR (Brazil)

    2013-01-01

    In recent years, many surface modification processes have been developed in order to induce the osseointegration on titanium surface and thus to improve the implants' biocompatibility. In this work, Ti surface has been modified by shot blasting followed by anodic oxidation process in order to associate the good surface characteristics of both processes to obtain a rough and porous surface able to promote the titanium surface bioactivity. Commercially pure titanium (grade 2) plates were used on the surface treatments that were as follows: Shot blasting (SB) performed using alumina (Al{sub 2}O{sub 3}) particles, and anodic oxidation (AO) using NaOH electrolyte. The morphology, structural changes and the open-circuit potentials (OCP) of the surfaces were analyzed. It can be observed that an increase on the roughness of the blasted surface and a rough and porous surface happens after the AO process. The anodic film produced is thin and followed the blasted surface topography. It can be observed that there are small pores with regular shape covering the entire surface. X-ray diffraction results showed the presence of the anatase and rutile phases on the blasted and anodized surface after heat treatment at 600 °C/1 h. Concerning electrochemical measurements, when the different samples were submitted to open-circuit conditions in a physiological electrolyte, the protective effect increases with the oxidation process due to the oxide layer. When the surface was blasted, the OCP was more negative when compared with the Ti surface without surface treatments. - Highlights: ► A combination of shot blasting and anodic oxidation surface treatments is proposed. ► Both processes produced an increase in roughness compared to the polished surface. ► The combination of processes produced a rough and porous surface. ► Open circuit results show that the protective effect increases with oxidation process. ► The combination of processes presents the better results in this

  8. Electrocatalytic oxidation of deferiprone and its determination on a carbon nanotube-modified glassy carbon electrode

    Yadegari, H. [Department of Chemistry, Faculty of Science, K.N. Toosi University of Technology, P.O. Box 16315-1618, Tehran (Iran, Islamic Republic of); Jabbari, A. [Department of Chemistry, Faculty of Science, K.N. Toosi University of Technology, P.O. Box 16315-1618, Tehran (Iran, Islamic Republic of)], E-mail: jabbari@kntu.ac.ir; Heli, H.; Moosavi-Movahedi, A.A. [Institute of Biochemistry and Biophysics, University of Tehran, Tehran (Iran, Islamic Republic of); Karimian, K. [Arasto Pharmaceutical Chemicals Inc., Tehran (Iran, Islamic Republic of); Khodadadi, A. [Department of Chemical Engineering, Faculty of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2008-02-15

    The electrochemical behavior of the anti-thalassemia and anti-HIV replication drug, deferiprone, was investigated on a carbon nanotube-modified glassy carbon (GC-CNT) electrode in phosphate buffer solution, pH 7.40 (PBS). During oxidation of deferiprone, two irreversible anodic peaks, with E{sub 1}{sup 0}=452 and E{sub 2}{sup 0}=906mV, appeared, using GC-CNT. Cyclic voltammetric study indicated that the oxidation process is irreversible and diffusion controlled. The number of exchanged electrons in the electro-oxidation process was obtained, and the data indicated that deferiprone is oxidized via two two-electron steps. The results revealed that carbon nanotube (CNT) promotes the rate of oxidation by increasing the peak current, so that deferiprone is oxidized at lower potentials, which thermodynamically is more favorable. This result was confirmed by impedance measurements. The diffusion coefficient, electron-transfer coefficient and heterogeneous electron-transfer rate constant of deferiprone were found to be 1.49 x 10{sup -6} cm{sup 2} s{sup -1}, 0.44, and 3.83 x 10{sup -3} cm s{sup -1}, respectively. A sensitive, simple and time-saving differential-pulse voltammetric procedure was developed for the analysis of deferiprone. Using the proposed method, deferiprone can be determined with a detection limit of 5.25 x 10{sup -7} M. The applicability of the method to direct assays of spiked human serum and urine fluids is described.

  9. The chemical and catalytic properties of nanocrystalline metal oxides prepared through modified sol-gel synthesis

    Carnes, Corrie Leigh

    The goal of this research was to synthesize, characterize and study the chemical properties of nanocrystalline metal oxides. Nanocrystalline (NC) ZnO, CuO, NiO, Al2O3, and the binary Al2O 3/MgO and ZnO/CuO were prepared through modified sol gel methods. These NC metal oxides were studied in comparison to the commercial (CM) metal oxides. The samples were characterized by XRD, TGA, FTIR, BET, and TEM. The NC samples were all accompanied by a significant increase in surface area and decrease in crystallite size. Several chemical reactions were studied to compare the NC samples to the CM samples. One of the reactions involved a high temperature reaction between carbon tetrachloride and the oxide to form carbon dioxide and the corresponding metal chloride. A similar high temperature reaction was conducted between the metal oxide and hydrogen sulfide to form water and the corresponding metal sulfide. A room temperature gas phase adsorption was studied where SO2 was adsorbed onto the oxide. A liquid phase adsorption conducted at room temperature was the destructive adsorption of paraoxon (a toxic insecticide). In all reactions the NC samples exhibited greater activity, destroying or adsorbing a larger amount of the toxins compared to the CM samples. To better study surface area effects catalytic reactions were also studied. The catalysis of methanol was studied over the nanocrystalline ZnO, CuO, NiO, and ZnO/CuO samples in comparison to their commercial counterparts. In most cases the NC samples proved to be more active catalysts, having higher percent conversions and turnover numbers. A second catalytic reaction was also studied, this reaction was investigated to look at the support effects. The catalysis of cyclopropane to propane was studied over Pt and Co catalysts. These catalysts were supported onto NC and CM alumina by impregnation. By observing differences in the catalytic behavior, support effects have become apparent.

  10. Selective recognition of DNA from olive leaves and olive oil by PNA and modified-PNA microarrays

    Rossi, Stefano; Calabretta, Alessandro; Tedeschi, Tullia; Sforza, Stefano; Arcioni, Sergio; Baldoni, Luciana; Corradini, Roberto; Marchelli, Rosangela

    2012-01-01

    PNA probes for the specific detection of DNA from olive oil samples by microarray technology were developed. The presence of as low as 5% refined hazelnut (Corylus avellana) oil in extra-virgin olive oil (Olea europaea L.) could be detected by using a PNA microarray. A set of two single nucleotide polymorphisms (SNPs) from the Actin gene of Olive was chosen as a model for evaluating the ability of PNA probes for discriminating olive cultivars. Both unmodified and C2-modified PNAs bearing an arginine side-chain were used, the latter showing higher sequence specificity. DNA extracted from leaves of three different cultivars (Ogliarola leccese, Canino and Frantoio) could be easily discriminated using a microarray with unmodified PNA probes, whereas discrimination of DNA from oil samples was more challenging, and could be obtained only by using chiral PNA probes. PMID:22772038

  11. DNA extraction techniques compared for accurate detection of genetically modified organisms (GMOs) in maize food and feed products.

    Turkec, Aydin; Kazan, Hande; Karacanli, Burçin; Lucas, Stuart J

    2015-08-01

    In this paper, DNA extraction methods have been evaluated to detect the presence of genetically modified organisms (GMOs) in maize food and feed products commercialised in Turkey. All the extraction methods tested performed well for the majority of maize foods and feed products analysed. However, the highest DNA content was achieved by the Wizard, Genespin or the CTAB method, all of which produced optimal DNA yield and purity for different maize food and feed products. The samples were then screened for the presence of GM elements, along with certified reference materials. Of the food and feed samples, 8 % tested positive for the presence of one GM element (NOS terminator), of which half (4 % of the total) also contained a second element (the Cauliflower Mosaic Virus 35S promoter). The results obtained herein clearly demonstrate the presence of GM maize in the Turkish market, and that the Foodproof GMO Screening Kit provides reliable screening of maize food and feed products.

  12. Electrocatalytic oxidation of some anti-inflammatory drugs on a nickel hydroxide-modified nickel electrode

    Hajjizadeh, M. [Department of Chemistry, Faculty of Science, K. N. Toosi University of Technology, P.O. Box 16315-1618, Tehran (Iran, Islamic Republic of); Jabbari, A. [Department of Chemistry, Faculty of Science, K. N. Toosi University of Technology, P.O. Box 16315-1618, Tehran (Iran, Islamic Republic of)], E-mail: jabbari@kntu.ac.ir; Heli, H.; Moosavi-Movahedi, A.A. [Institute of Biochemistry and Biophysics, University of Tehran, Tehran (Iran, Islamic Republic of); Haghgoo, S. [Center of Quality Control of Drug, Tehran (Iran, Islamic Republic of)

    2007-12-31

    The electrocatalytic oxidation of several anti-inflammatory drugs (mefenamic acid, diclofenac and indomethacin) was investigated on a nickel hydroxide-modified nickel (NHMN) electrode in alkaline solution. This oxidation process and its kinetics were studied using cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy techniques. Voltammetric studies indicated that in the presence of drugs, the anodic peak current of low-valence nickel species increases, followed by a decrease in the corresponding cathodic current. This pattern indicates that drugs were oxidized on the redox mediator immobilized on the electrode surface via an electrocatalytic mechanism. A mechanism based on the electrochemical generation of Ni(III) active sites and their subsequent consumption by drugs was also investigated. The corresponding rate law under the control of charge transfer was developed and kinetic parameters were derived. In this context, the charge-transfer resistance accessible both theoretically and through impedancemetry was used as a criterion. The rate constants of the catalytic oxidation of drugs and the electron-transfer coefficients are reported. A sensitive, simple and time-saving amperometric procedure was developed for the analysis of these drugs in bulk form and for the direct assay of tablets, using the NHMN electrode.

  13. Electrocatalytic oxidation of some anti-inflammatory drugs on a nickel hydroxide-modified nickel electrode

    Hajjizadeh, M.; Jabbari, A.; Heli, H.; Moosavi-Movahedi, A.A.; Haghgoo, S.

    2007-01-01

    The electrocatalytic oxidation of several anti-inflammatory drugs (mefenamic acid, diclofenac and indomethacin) was investigated on a nickel hydroxide-modified nickel (NHMN) electrode in alkaline solution. This oxidation process and its kinetics were studied using cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy techniques. Voltammetric studies indicated that in the presence of drugs, the anodic peak current of low-valence nickel species increases, followed by a decrease in the corresponding cathodic current. This pattern indicates that drugs were oxidized on the redox mediator immobilized on the electrode surface via an electrocatalytic mechanism. A mechanism based on the electrochemical generation of Ni(III) active sites and their subsequent consumption by drugs was also investigated. The corresponding rate law under the control of charge transfer was developed and kinetic parameters were derived. In this context, the charge-transfer resistance accessible both theoretically and through impedancemetry was used as a criterion. The rate constants of the catalytic oxidation of drugs and the electron-transfer coefficients are reported. A sensitive, simple and time-saving amperometric procedure was developed for the analysis of these drugs in bulk form and for the direct assay of tablets, using the NHMN electrode

  14. The effects of cetyltrimethylammonium bromide surfactant on alumina modified zinc oxides

    Gac, Wojciech, E-mail: wojciech.gac@umcs.lublin.pl [Department of Chemical Technology, Faculty of Chemistry, Maria Curie-Sklodowska University, 3 M. Curie-Sklodowska Sq., 20-031 Lublin (Poland); Zawadzki, Witold; Słowik, Grzegorz; Pawlonka, Justyna; Machocki, Andrzej [Department of Chemical Technology, Faculty of Chemistry, Maria Curie-Sklodowska University, 3 M. Curie-Sklodowska Sq., 20-031 Lublin (Poland); Lipke, Agnieszka; Majdan, Marek [Department of Inorganic Chemistry, Faculty of Chemistry, Maria Curie-Sklodowska University, 2 M. Curie-Sklodowska Sq., 20-031 Lublin (Poland)

    2016-06-15

    Highlights: • Synthesis of novel ZnO−Al{sub 2}O{sub 3} oxides in the presence of CTAB surfactant. • Determination of the structural, surface and optical properties. • Nanocrystalline, high-surface area ZnO−Al{sub 2}O{sub 3} oxides. • ZnO-Al{sub 2}O{sub 3} materials of different gap energy. - Abstract: Novel alumina modified zinc oxide materials were prepared by co-precipitation method in the presence of different amounts of cetyltrimethylammonium bromide (CTAB) surfactant. X-ray diffraction, {sup 27}Al magic-angle spinning Nuclear Magnetic Resonance Spectroscopy, and transmission electron microscopy studies evidenced formation of 10–15 nm zinc oxide nanoparticles in the presence of the small amounts of surfactant. Amorphous alumina and zinc aluminate phases of different coordination environment of Al sites were identified. An increase of surfactant concentration led to the elongation of nanoparticles and changes of the nature of hydroxyl groups. Precipitation in the high CTAB concentration conditions facilitated formation of mesoporous materials of high specific surface area. The materials were composed of very small (2–3 nm) zinc aluminate spinel nanoparticles. High concentration of CTAB induced widening of band gap energy.

  15. Simultaneous determination of dopamine, uric acid and nitrite using carboxylated graphene oxide/lanthanum modified electrode

    Ye, Fengying; Feng, Chenqi; Jiang, Jibo; Han, Sheng

    2015-01-01

    Highlights: • The carboxylated graphene oxide/lanthanum-modified glassy carbon electrode (GO-COOLa/GCE) was successfully utilized for the simultaneous detection and quantification of DA, UA and NO 2 − . • Combining the benefits of carboxylated graphene oxide and lanthanum, the modified sensor displayed large peak separations, long linear ranges and low detection limits for simultaneously detecting DA, UA and NO 2 − . • The GO-COOLa/GCE electrode showed well stability, good repeatability, rapid response, and high catalytic performance toward the oxidations of DA, UA and NO 2 − . - Abstract: A bare glassy carbon electrode (GCE) was reformed by carboxylated graphene oxide/lanthanum, and the modified electrode, called GO-COOLa/GCE, was fabricated for simultaneously detecting dopamine (DA), uric acid (UA) and nitrite (NO 2 − ) by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry. Several factors which affected the electrocatalytic activity of the GO-COOLa/GCE electrode, such as the effect of pH, scan rate and concentration were studied. Due to the combination of carboxylated graphene oxide and lanthanum ions, the GO-COOLa/GCE sensor showed rapid response, excellent selectivity and high catalytic performance toward the electrooxidation of DA, UA and NO 2 − . In optimized conditions, two linear response ranges for determining DA were obtained over ranges of 0.01-1.96×10 2 μM and 1.96×10 2 -1.23×10 3 μM with detection limit of 0.018 μM (S/N = 3). And the responses of the GO-COOLa/GCE electrode for UA and NO 2 − were linear in the region of 1-1.53×10 3 μM and 1-2.75×10 3 μM with detection limits of 0.058 μM and 0.070 μM, respectively. Furthermore, this reformed electrode was successfully used to the detection of DA, UA and NO 2 − in real urine and serum samples, showing its promising application in the electroanalysis of real samples.

  16. Conductivity of Pedot-Pss with Gold and Silver Nanocomposites Modified Gold Electrodes for Ganoderma Boninense DNA Detection

    Sabo Wada Dutse

    2015-08-01

    Full Text Available The conductivity of a designed electrochemical DNA biosensor was improved using gold and or silver nanoparticles. A gold electrode modified with a conductive nanocomposite of poly(3,4-ethylene dioxythiophen–poly (styrenesulfonate (Pedot-Pss and gold or silver nano particles enhanced the conductivity of the electrode surface area. Bare and modified gold electrode surfaces were characterized using cyclic voltammetry (CV technique in ethylenediaminetetraacetic acid (TE supporting electrolyte. Immobilization of a 20-mer DNA probe was achieved by covalent attachment of the amine group of the capture probe to a carboxylic group of an activated 3,3’-dithiodipropionic acid layer using EDC/NHSS for Hybridization. The effect of hybridization temperature and time was optimized and the sensor demonstrated specific detection for the target concentration ranged between 1.0´10-15 M to 1.0´10-9 M with a detection limit of 9.70´10-19 M. Control experiments verified the specificity of the biosensor in the presence of mismatched DNA sequence. The DNA hybridization was monitored using a new ruthenium complex [Ru(dppz2(qtpyCl2; dppz = dipyrido [3,2–a:2’,3’-c] phenazine; qtpy=2,2’,-4,4”.4’4”’-quarterpyridyl redox indicator.

  17. Environmental ozone exposure and oxidative DNA damage in adult residents of Florence, Italy

    Palli, Domenico, E-mail: d.palli@ispo.toscana.i [Molecular and Nutritional Epidemiology Unit, Cancer Prevention and Research Institute (ISPO), Via Cosimo il Vecchio 2, 50139 Florence (Italy); Sera, Francesco, E-mail: f.sera@ispo.toscana.i [Molecular and Nutritional Epidemiology Unit, Cancer Prevention and Research Institute (ISPO), Via Cosimo il Vecchio 2, 50139 Florence (Italy); Giovannelli, Lisa, E-mail: lisag@pharm.unifi.i [Department of Pharmacology, University of Florence, Viale G.Pieraccini 6, 50139 Florence (Italy); Masala, Giovanna, E-mail: g.masala@ispo.toscana.i [Molecular and Nutritional Epidemiology Unit, Cancer Prevention and Research Institute (ISPO), Via Cosimo il Vecchio 2, 50139 Florence (Italy); Grechi, Daniele [Regional Environmental Protection Agency of Tuscany (ARPAT), Via Porpora 22, 50144 Florence (Italy); Bendinelli, Benedetta, E-mail: b.bendinelli@ispo.toscana.i [Molecular and Nutritional Epidemiology Unit, Cancer Prevention and Research Institute (ISPO), Via Cosimo il Vecchio 2, 50139 Florence (Italy); Caini, Saverio, E-mail: s.caini@ispo.toscana.i [Molecular and Nutritional Epidemiology Unit, Cancer Prevention and Research Institute (ISPO), Via Cosimo il Vecchio 2, 50139 Florence (Italy); Dolara, Piero, E-mail: piero.dolara@unifi.i [Department of Pharmacology, University of Florence, Viale G.Pieraccini 6, 50139 Florence (Italy); Saieva, Calogero, E-mail: c.saieva@ispo.toscana.i [Molecular and Nutritional Epidemiology Unit, Cancer Prevention and Research Institute (ISPO), Via Cosimo il Vecchio 2, 50139 Florence (Italy)

    2009-05-15

    In 71 adults residing in Florence, Italy, enrolled in a prospective study, we investigated the correlation between individual levels of oxidative DNA damage detected by the Comet assay in circulating lymphocytes, and a specific ozone exposure score calculated in 10 different time-windows (0-5 to 0-90 days) before blood drawing, based on daily measurements provided by the local environmental monitoring system. Overall, statistically significant positive correlations between average ozone concentrations and DNA damage emerged in almost all time-windows considered; correlations were more evident among males, non-smokers, and traffic-exposed workers. Multivariate regression analyses taking into account selected individual characteristics, showed an independent effect on DNA damage of average ozone concentrations in the last 60-90 days before blood drawing. Local residents showed a divergent pattern with correlations restricted to shorter time-windows. Our results suggest that ozone concentrations at ground levels modulate oxidative DNA damage in circulating lymphocytes of residents of polluted areas. - Ozone concentrations over the 60-90 days before blood drawing correlated with DNA damage in circulating lymphocytes of adults living in the metropolitan area of Florence, Italy.

  18. Environmental ozone exposure and oxidative DNA damage in adult residents of Florence, Italy

    Palli, Domenico; Sera, Francesco; Giovannelli, Lisa; Masala, Giovanna; Grechi, Daniele; Bendinelli, Benedetta; Caini, Saverio; Dolara, Piero; Saieva, Calogero

    2009-01-01

    In 71 adults residing in Florence, Italy, enrolled in a prospective study, we investigated the correlation between individual levels of oxidative DNA damage detected by the Comet assay in circulating lymphocytes, and a specific ozone exposure score calculated in 10 different time-windows (0-5 to 0-90 days) before blood drawing, based on daily measurements provided by the local environmental monitoring system. Overall, statistically significant positive correlations between average ozone concentrations and DNA damage emerged in almost all time-windows considered; correlations were more evident among males, non-smokers, and traffic-exposed workers. Multivariate regression analyses taking into account selected individual characteristics, showed an independent effect on DNA damage of average ozone concentrations in the last 60-90 days before blood drawing. Local residents showed a divergent pattern with correlations restricted to shorter time-windows. Our results suggest that ozone concentrations at ground levels modulate oxidative DNA damage in circulating lymphocytes of residents of polluted areas. - Ozone concentrations over the 60-90 days before blood drawing correlated with DNA damage in circulating lymphocytes of adults living in the metropolitan area of Florence, Italy.

  19. DNA-length-dependent quenching of fluorescently labeled iron oxide nanoparticles with gold, graphene oxide and MoS2 nanostructures.

    Balcioglu, Mustafa; Rana, Muhit; Robertson, Neil; Yigit, Mehmet V

    2014-08-13

    We controlled the fluorescence emission of a fluorescently labeled iron oxide nanoparticle using three different nanomaterials with ultraefficient quenching capabilities. The control over the fluorescence emission was investigated via spacing introduced by the surface-functionalized single-stranded DNA molecules. DNA molecules were conjugated on different templates, either on the surface of the fluorescently labeled iron oxide nanoparticles or gold and nanographene oxide. The efficiency of the quenching was determined and compared with various fluorescently labeled iron oxide nanoparticle and nanoquencher combinations using DNA molecules with three different lengths. We have found that the template for DNA conjugation plays significant role on quenching the fluorescence emission of the fluorescently labeled iron oxide nanoparticles. We have observed that the size of the DNA controls the quenching efficiency when conjugated only on the fluorescently labeled iron oxide nanoparticles by setting a spacer between the surfaces and resulting change in the hydrodynamic size. The quenching efficiency with 12mer, 23mer and 36mer oligonucleotides decreased to 56%, 54% and 53% with gold nanoparticles, 58%, 38% and 32% with nanographene oxide, 46%, 38% and 35% with MoS2, respectively. On the other hand, the presence, not the size, of the DNA molecules on the other surfaces quenched the fluorescence significantly with different degrees. To understand the effect of the mobility of the DNA molecules on the nanoparticle surface, DNA molecules were attached to the surface with two different approaches. Covalently immobilized oligonucleotides decreased the quenching efficiency of nanographene oxide and gold nanoparticles to ∼22% and ∼21%, respectively, whereas noncovalently adsorbed oligonucleotides decreased it to ∼25% and ∼55%, respectively. As a result, we have found that each nanoquencher has a powerful quenching capability against a fluorescent nanoparticle, which can be

  20. Potent protection of gallic acid against DNA oxidation: Results of human and animal experiments

    Ferk, Franziska; Chakraborty, Asima; Jaeger, Walter; Kundi, Michael; Bichler, Julia; Misik, Miroslav; Wagner, Karl-Heinz; Grasl-Kraupp, Bettina; Sagmeister, Sandra; Haidinger, Gerald; Hoelzl, Christine; Nersesyan, Armen; Dusinska, Maria; Simic, Tatjana; Knasmueller, Siegfried

    2011-01-01

    Gallic acid (3,4,5-trihydroxybenzoic acid, GA) is a constituent of plant derived foods, beverages and herbal remedies. We investigated its DNA protective properties in a placebo controlled human intervention trial in single cell gel electrophoresis experiments. Supplementation of drinking water with GA (12.8 mg/person/d) for three days led to a significant reduction of DNA migration attributable to oxidised pyrimidines (endonuclease III sensitive sites) and oxidised purines (formamidopyrimidine glycosylase sensitive sites) in lymphocytes of healthy individuals by 75% and 64% respectively. Also DNA damage caused by treatment of the cells with reactive oxygen species (ROS) was reduced after GA consumption (by 41%). These effects were paralleled by an increase of the activities of antioxidant enzymes (superoxide dismutase, glutathione peroxidase and glutathion-S-transferase-π) and a decrease of intracellular ROS concentrations in lymphocytes, while no alterations of the total antioxidant capacity (TAC), of malondialdehyde levels in serum and of the urinary excretion of isoprostanes were found. Experiments with rats showed that GA reduces oxidatively damaged DNA in lymphocytes, liver, colon and lungs and protects these organs against γ-irradiation-induced strand breaks and formation of oxidatively damaged DNA-bases. Furthermore, the number of radiation-induced preneoplastic hepatic foci was decreased by 43% after oral administration of the phenolic. Since we did not find alterations of the TAC in plasma and lipid peroxidation of cell membranes but intracellular effects it is likely that the antioxidant properties of GA seen in vivo are not due to direct scavenging of radicals but rather to indirect mechanisms (e.g. protection against ROS via activation of transcription factors). As the amount of GA used in the intervention trial is similar to the daily intake in Middle Europe (18 mg/person/day), our findings indicate that it may contribute to prevention of formation

  1. Potent protection of gallic acid against DNA oxidation: Results of human and animal experiments

    Ferk, Franziska; Chakraborty, Asima [Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, A-1090 Vienna (Austria); Jaeger, Walter [Department of Clinical Pharmacy and Diagnostic, University of Vienna, Vienna (Austria); Kundi, Michael [Institute of Environmental Health, Center for Public Health, Medical University of Vienna, A-1090 Vienna (Austria); Bichler, Julia; Misik, Miroslav [Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, A-1090 Vienna (Austria); Wagner, Karl-Heinz [Department of Nutritional Sciences, University of Vienna, 1090 Vienna (Austria); Grasl-Kraupp, Bettina; Sagmeister, Sandra [Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, A-1090 Vienna (Austria); Haidinger, Gerald [Department of Epidemiology, Center for Public Health, Medical University of Vienna, A-1090 Vienna (Austria); Hoelzl, Christine; Nersesyan, Armen [Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, A-1090 Vienna (Austria); Dusinska, Maria [Health Effect Laboratory, Center for Ecological Economics, Norwegian Institute for Air Research, NO-2027 Kjeller (Norway); Simic, Tatjana [Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, A-1090 Vienna (Austria); Knasmueller, Siegfried, E-mail: siegfried.knasmueller@meduniwien.ac.at [Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, A-1090 Vienna (Austria)

    2011-10-01

    Gallic acid (3,4,5-trihydroxybenzoic acid, GA) is a constituent of plant derived foods, beverages and herbal remedies. We investigated its DNA protective properties in a placebo controlled human intervention trial in single cell gel electrophoresis experiments. Supplementation of drinking water with GA (12.8 mg/person/d) for three days led to a significant reduction of DNA migration attributable to oxidised pyrimidines (endonuclease III sensitive sites) and oxidised purines (formamidopyrimidine glycosylase sensitive sites) in lymphocytes of healthy individuals by 75% and 64% respectively. Also DNA damage caused by treatment of the cells with reactive oxygen species (ROS) was reduced after GA consumption (by 41%). These effects were paralleled by an increase of the activities of antioxidant enzymes (superoxide dismutase, glutathione peroxidase and glutathion-S-transferase-{pi}) and a decrease of intracellular ROS concentrations in lymphocytes, while no alterations of the total antioxidant capacity (TAC), of malondialdehyde levels in serum and of the urinary excretion of isoprostanes were found. Experiments with rats showed that GA reduces oxidatively damaged DNA in lymphocytes, liver, colon and lungs and protects these organs against {gamma}-irradiation-induced strand breaks and formation of oxidatively damaged DNA-bases. Furthermore, the number of radiation-induced preneoplastic hepatic foci was decreased by 43% after oral administration of the phenolic. Since we did not find alterations of the TAC in plasma and lipid peroxidation of cell membranes but intracellular effects it is likely that the antioxidant properties of GA seen in vivo are not due to direct scavenging of radicals but rather to indirect mechanisms (e.g. protection against ROS via activation of transcription factors). As the amount of GA used in the intervention trial is similar to the daily intake in Middle Europe (18 mg/person/day), our findings indicate that it may contribute to prevention of

  2. Sensitive DNA impedance biosensor for detection of cancer, chronic lymphocytic leukemia, based on gold nanoparticles/gold modified electrode

    Ensafi, Ali A.; Taei, M.; Rahmani, H.R.; Khayamian, T.

    2011-01-01

    Highlights: → Chronic lymphocytic leukemia causes an increase in the number of white blood cells. → We introduced a highly sensitive biosensor for the detection of chronic lymphocytic leukemia. → A suitable 25-mer ssDNA probe was immobilized on the surface of the gold nanoparticles. → We used electrochemical impedance spectroscopy as a suitable tool for the detection. → Detection of chronic lymphocytic leukemia in blood sample was checked using the sensor. - Abstract: A simple and sensitive DNA impedance sensor was prepared for the detection of chronic lymphocytic leukemia. The DNA electrochemical biosensor is worked based on the electrochemical impedance spectroscopic (EIS) detection of the sequence-specific DNA related to chronic lymphocytic leukemia. The ssDNA probe was immobilized on the surface of the gold nanoparticles. Compared to the bare gold electrode, the gold nanoparticles-modified electrode could improve the density of the probe DNA attachment and hence the sensitivity of the DNA sensor greatly. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy were performed in a solution containing 1.0 mmol L -1 K 3 [Fe(CN) 6 ]/K 4 [Fe(CN) 6 ] and 50 mmol L -1 phosphate buffer saline pH 6.87 plus 50 mmol L -1 KCl. In the CV studied, the potential was cycled from 0.0 to +0.65 V with a scan rate of 50 mV s -1 . Using EIS, the difference of the electron transfer resistance (ΔR et ) was linear with the logarithm of the complementary oligonucleotides sequence concentrations in the range of 7.0 x 10 -12 -2.0 x 10 -7 mol L -1 , with a detection limit of 1.0 x 10 -12 mol L -1 . In addition, the DNA sensor showed a good reproducibility and stability during repeated regeneration and hybridization cycles.

  3. Oxidative damage to DNA by diesel exhaust particle exposure in co-cultures of human lung epithelial cells and macrophages

    Jantzen, Kim; Roursgaard, Martin; Madsen, Claus Desler

    2012-01-01

    Studies in mono-culture of cells have shown that diesel exhaust particles (DEPs) increase the production of reactive oxygen species (ROS) and oxidative stress-related damage to DNA. However, the level of particle-generated genotoxicity may depend on interplay between different cell types, e.g. lung...... treatment with standard reference DEPs, SRM2975 and SRM1650b. The exposure to DEPs did not affect the colony-forming ability of A549 cells in co-culture with THP-1a cells. The DEPs generated DNA strand breaks and oxidatively damaged DNA, measured using the alkaline comet assay as formamidopyrimidine...... relationship between levels of respiration and ROS production. In conclusion, exposure of mono-cultured cells to DEPs generated oxidative stress to DNA, whereas co-cultures with macrophages had lower levels of oxidatively damaged DNA than A549 epithelial cells....

  4. Alpha-Lipoic acid counteracts the promoted oxidative DNA damage in the liver of septic rats

    Abd-Allah, Adel R.A.

    2006-01-01

    Viral, parasitic infections and chemical carcinogens are among the etiological factors of liver cancer. It seems important to study the initiating and promoting agents to evaluate the etiology and prevention of such life threatening disease. Intestine-derived bacteria product, lipopolysaccharide (LPS), is mainly detoxified by the liver. It has shown to induce a state of oxidative DNA damage is not fully investigated. Increased oxidative DNA damage and rate of cell proliferation may initiate or even promote cancer. In the present work, the capability of LPS to induce 8-hydroxydeoxyguanosine (8-HDG), a specific DNA adduct for oxidative DNA damage, in rat livers is tested. Furthermore, a possible protective effect of alpha lipoic acid (ALA) is also assessed. Investigated parameters are liver contents of glutathione (GSH), lipid peroxides (MDA), nitric oxide (NO) and 8-HDG in the liver-extracted DNA. Serum activities of ALT, AST and GGT as liver-function markers as well as IL2 are assessed. Moreover, liver histology is examined. LPS was given doses of 1, 3, 5, 7 and 9 mg/kg once i.p. while, the rat mortality was examined 24 hours later. ALA was given in doses of 50, 100 and 200 mg/kg once i.p. 3h before LPS is found to be 5mg/kg. LPS increased the level of 8-HDG, MDA and NO in the liver. It also induced acute liver necrosis and inflammatory cell infiltration as shown in liver-histopathology and in the significant increase in the activities of ALT, AST and GGT. LPS increased the serum level of IL2 as well. The dose 200mg/kg of ALA revealed a 100% protection against LPS-induced lethality. It also, prevented the LPS-induced increase in 8-HDG in liver extracted DNA, the liver contents of MDA and NO. ALA also rescued the LPS-induced GSH depletion. It corrected the liver function as shown by the prevention of increases in the activity of ALT, AST and GGT with a remarkable improvement in the liver histology. Moreover, it prevented the increase in serum level of IL2. These

  5. Anthraquinone as a Redox Label for DNA: Synthesis, Enzymatic Incorporation, and Electrochemistry of Anthraquinone-Modified Nucleosides, Nucleotides, and DNA

    Balintová, Jana; Pohl, Radek; Horáková Brázdilová, Petra; Vidláková, Pavlína; Havran, Luděk; Fojta, Miroslav; Hocek, Michal

    2011-01-01

    Roč. 17, č. 50 (2011), s. 14063-14073 ISSN 0947-6539 R&D Projects: GA MŠk(CZ) LC06035; GA MŠk LC512; GA AV ČR(CZ) IAA400040901 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : anthraquinone * DNA * electrochemistry * nucleosides * oligonucleotides Subject RIV: CC - Organic Chemistry Impact factor: 5.925, year: 2011

  6. Xeroderma Pigmentosum Group A Suppresses Mutagenesis Caused by Clustered Oxidative DNA Adducts in the Human Genome

    Sassa, Akira; Kamoshita, Nagisa; Kanemaru, Yuki; Honma, Masamitsu; Yasui, Manabu

    2015-01-01

    Clustered DNA damage is defined as multiple sites of DNA damage within one or two helical turns of the duplex DNA. This complex damage is often formed by exposure of the genome to ionizing radiation and is difficult to repair. The mutagenic potential and repair mechanisms of clustered DNA damage in human cells remain to be elucidated. In this study, we investigated the involvement of nucleotide excision repair (NER) in clustered oxidative DNA adducts. To identify the in vivo protective roles of NER, we established a human cell line lacking the NER gene xeroderma pigmentosum group A (XPA). XPA knockout (KO) cells were generated from TSCER122 cells derived from the human lymphoblastoid TK6 cell line. To analyze the mutagenic events in DNA adducts in vivo, we previously employed a system of tracing DNA adducts in the targeted mutagenesis (TATAM), in which DNA adducts were site-specifically introduced into intron 4 of thymidine kinase genes. Using the TATAM system, one or two tandem 7,8-dihydro-8-oxoguanine (8-oxoG) adducts were introduced into the genomes of TSCER122 or XPA KO cells. In XPA KO cells, the proportion of mutants induced by a single 8-oxoG (7.6%) was comparable with that in TSCER122 cells (8.1%). In contrast, the lack of XPA significantly enhanced the mutant proportion of tandem 8-oxoG in the transcribed strand (12%) compared with that in TSCER122 cells (7.4%) but not in the non-transcribed strand (12% and 11% in XPA KO and TSCER122 cells, respectively). By sequencing the tandem 8-oxoG-integrated loci in the transcribed strand, we found that the proportion of tandem mutations was markedly increased in XPA KO cells. These results indicate that NER is involved in repairing clustered DNA adducts in the transcribed strand in vivo. PMID:26559182

  7. Xeroderma Pigmentosum Group A Suppresses Mutagenesis Caused by Clustered Oxidative DNA Adducts in the Human Genome.

    Sassa, Akira; Kamoshita, Nagisa; Kanemaru, Yuki; Honma, Masamitsu; Yasui, Manabu

    2015-01-01

    Clustered DNA damage is defined as multiple sites of DNA damage within one or two helical turns of the duplex DNA. This complex damage is often formed by exposure of the genome to ionizing radiation and is difficult to repair. The mutagenic potential and repair mechanisms of clustered DNA damage in human cells remain to be elucidated. In this study, we investigated the involvement of nucleotide excision repair (NER) in clustered oxidative DNA adducts. To identify the in vivo protective roles of NER, we established a human cell line lacking the NER gene xeroderma pigmentosum group A (XPA). XPA knockout (KO) cells were generated from TSCER122 cells derived from the human lymphoblastoid TK6 cell line. To analyze the mutagenic events in DNA adducts in vivo, we previously employed a system of tracing DNA adducts in the targeted mutagenesis (TATAM), in which DNA adducts were site-specifically introduced into intron 4 of thymidine kinase genes. Using the TATAM system, one or two tandem 7,8-dihydro-8-oxoguanine (8-oxoG) adducts were introduced into the genomes of TSCER122 or XPA KO cells. In XPA KO cells, the proportion of mutants induced by a single 8-oxoG (7.6%) was comparable with that in TSCER122 cells (8.1%). In contrast, the lack of XPA significantly enhanced the mutant proportion of tandem 8-oxoG in the transcribed strand (12%) compared with that in TSCER122 cells (7.4%) but not in the non-transcribed strand (12% and 11% in XPA KO and TSCER122 cells, respectively). By sequencing the tandem 8-oxoG-integrated loci in the transcribed strand, we found that the proportion of tandem mutations was markedly increased in XPA KO cells. These results indicate that NER is involved in repairing clustered DNA adducts in the transcribed strand in vivo.

  8. Taurine protects DNA of lymphocytes against oxidative alteration in riding horses

    Sokól, Janusz Leszek; Sawosz, Ewa; Niemiec, Tomasz

    2009-01-01

    The study aimed at evaluation the effect of dietary supplement of taurine on the oxidation-reduction status in riding horses, and especially on the extent of oxidative DNA degradation in lymphocytes. Ten Thoroughbred and half-bred geldings aged 6-13 years were classified according to breed...... and amount of work done into two groups - control (C, n=5) and experimental (E, n=5), the latter fed the diet with addition of 40 g taurine/horse/day. Blood samples were withdrawn from the horses' jugular vein before commencing the riding season and then after 30 days of working. In the blood some selected....... The addition of taurine to feed caused smaller oxidative stress, manifested by lower concentration of TBA-RS in plasma and of 8-oxo-dG in lymphocytes. The taurine lowered the lipid peroxidation intensity that occurred in horses due to the oxidative stress caused by physical effort. Furthermore, taurine...

  9. Daily grape juice consumption reduces oxidative DNA damage and plasma free radical levels in healthy Koreans

    Park, Yoo Kyoung; Park, Eunju; Kim, Jung-Shin; Kang, Myung-Hee

    2003-01-01

    Grape contains flavonoids with antioxidant properties which are believed to be protective against various types of cancer. This antioxidative protection is possibly provided by the effective scavenging of reactive oxygen species (ROS), thus defending cellular DNA from oxidative damage and potential mutations. This study of healthy adults tested whether a daily regimen of grape juice supplementation could reduce cellular DNA damage in peripheral lymphocytes and reduce the amount of free radicals released. Sixty-seven healthy volunteers (16 women and 51 men) aged 19-57 years were given 480 ml of grape juice daily for 8 weeks in addition to their normal diet, and blood samples were drawn before and after the intervention. The DNA damage was determined by using the single cell gel (comet) assay with alkaline electrophoresis and was quantified by measuring tail length (TL). Levels of free radicals were determined by reading the lucigenin-perborate ROS generating source, using the Ultra-Weak Chemiluminescence Analyzer System. Grape juice consumption resulted in a significant decrease in lymphocyte DNA damage expressed by TL (before supplementation: 88.75±1.55 μm versus after supplementation: 70.25±1.31 μm; P=0.000 by paired t-test). Additionally, grape juice consumption for 8 weeks reduced the ROS/photon count by 15%, compared to the beginning of the study. The preventive effect of grape juice against DNA damage was simultaneously shown in both sexes. These results indicate that the consumption of grape juice may increase plasma antioxidant capacity, resulting in reduced DNA damage in peripheral lymphocytes achieved at least partially by a reduced release of ROS. Our findings support the hypothesis that polyphenolic compounds contained in grape juice exert cancer-protective effects on lymphocytes, limiting oxidative DNA damage possibly via a decrease in free radical levels

  10. Daily grape juice consumption reduces oxidative DNA damage and plasma free radical levels in healthy Koreans

    Park, Yoo Kyoung; Park, Eunju; Kim, Jung-Shin; Kang, Myung-Hee

    2003-08-28

    Grape contains flavonoids with antioxidant properties which are believed to be protective against various types of cancer. This antioxidative protection is possibly provided by the effective scavenging of reactive oxygen species (ROS), thus defending cellular DNA from oxidative damage and potential mutations. This study of healthy adults tested whether a daily regimen of grape juice supplementation could reduce cellular DNA damage in peripheral lymphocytes and reduce the amount of free radicals released. Sixty-seven healthy volunteers (16 women and 51 men) aged 19-57 years were given 480 ml of grape juice daily for 8 weeks in addition to their normal diet, and blood samples were drawn before and after the intervention. The DNA damage was determined by using the single cell gel (comet) assay with alkaline electrophoresis and was quantified by measuring tail length (TL). Levels of free radicals were determined by reading the lucigenin-perborate ROS generating source, using the Ultra-Weak Chemiluminescence Analyzer System. Grape juice consumption resulted in a significant decrease in lymphocyte DNA damage expressed by TL (before supplementation: 88.75{+-}1.55 {mu}m versus after supplementation: 70.25{+-}1.31 {mu}m; P=0.000 by paired t-test). Additionally, grape juice consumption for 8 weeks reduced the ROS/photon count by 15%, compared to the beginning of the study. The preventive effect of grape juice against DNA damage was simultaneously shown in both sexes. These results indicate that the consumption of grape juice may increase plasma antioxidant capacity, resulting in reduced DNA damage in peripheral lymphocytes achieved at least partially by a reduced release of ROS. Our findings support the hypothesis that polyphenolic compounds contained in grape juice exert cancer-protective effects on lymphocytes, limiting oxidative DNA damage possibly via a decrease in free radical levels.

  11. Mitochondrial DNA damage and oxidative damage in HL-60 cells exposed to 900 MHz radiofrequency fields

    Sun, Yulong; Zong, Lin; Gao, Zhen [School of Public Health, Soochow University, Suzhou, Jiangsu Province (China); Zhu, Shunxing [Laboratory Animal Center, Nantong University, Nantong, Jiangsu Province (China); Tong, Jian [School of Public Health, Soochow University, Suzhou, Jiangsu Province (China); Cao, Yi, E-mail: yicao@suda.edu.cn [School of Public Health, Soochow University, Suzhou, Jiangsu Province (China)

    2017-03-15

    Highlights: • Increased reactive oxygen species. • Decreased mitochondrial transcription Factor A and polymerase gamma. • Decreased mitochondrial transcripts (ND1 and 16S) and mtDNA copy number. • Increased 8-hydroxy-2′deoxyguanosine. • Decreased adenosine triphosphate. - Abstract: HL-60 cells, derived from human promyelocytic leukemia, were exposed to continuous wave 900 MHz radiofrequency fields (RF) at 120 μW/cm{sup 2} power intensity for 4 h/day for 5 consecutive days to examine whether such exposure is capable damaging the mitochondrial DNA (mtDNA) mediated through the production of reactive oxygen species (ROS). In addition, the effect of RF exposure was examined on 8-hydroxy-2′-dexoyguanosine (8-OHdG) which is a biomarker for oxidative damage and on the mitochondrial synthesis of adenosine triphosphate (ATP) which is the energy required for cellular functions. The results indicated a significant increase in ROS and significant decreases in mitochondrial transcription factor A, mtDNA polymerase gamma, mtDNA transcripts and mtDNA copy number in RF-exposed cells compared with those in sham-exposed control cells. In addition, there was a significant increase in 8-OHdG and a significant decrease in ATP in RF-exposed cells. The response in positive control cells exposed to gamma radiation (GR, which is also known to induce ROS) was similar to those in RF-exposed cells. Thus, the overall data indicated that RF exposure was capable of inducing mtDNA damage mediated through ROS pathway which also induced oxidative damage. Prior-treatment of RF- and GR-exposed the cells with melatonin, a well-known free radical scavenger, reversed the effects observed in RF-exposed cells.

  12. A highly sensitive electrochemical biosensor for catechol using conducting polymer reduced graphene oxide-metal oxide enzyme modified electrode.

    Sethuraman, V; Muthuraja, P; Anandha Raj, J; Manisankar, P

    2016-10-15

    The fabrication, characterization and analytical performances were investigated for a catechol biosensor, based on the PEDOT-rGO-Fe2O3-PPO composite modified glassy carbon (GC) electrode. The graphene oxide (GO) doped conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) was prepared through electrochemical polymerization by potential cycling. Reduction of PEDOT-GO was carried out by amperometric method. Fe2O3 nanoparticles were synthesized in ethanol by hydrothermal method. The mixture of Fe2O3, PPO and glutaraldehyde was casted on the PEDOT-rGO electrode. The surface morphology of the modified electrodes was studied by FE-SEM and AFM. Cyclic voltammetric studies of catechol on the enzyme modified electrode revealed higher reduction peak current. Determination of catechol was carried out successfully by Differential Pulse Voltammetry (DPV) technique. The fabricated biosensor investigated shows a maximum current response at pH 6.5. The catechol biosensor exhibited wide sensing linear range from 4×10(-8) to 6.20×10(-5)M, lower detection limit of 7×10(-9)M, current maxima (Imax) of 92.55µA and Michaelis-Menten (Km) constant of 30.48µM. The activation energy (Ea) of enzyme electrode is 35.93KJmol(-1) at 50°C. There is no interference from d-glucose and l-glutamic acid, ascorbic acid and o-nitrophenol. The PEDOT-rGO-Fe2O3-PPO biosensor was stable for at least 75 days when stored in a buffer at about 4°C. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Surface Properties of PAN-based Carbon Fibers Modified by Electrochemical Oxidization in Organic Electrolyte Systems

    WU Bo

    2016-09-01

    Full Text Available PAN-based carbon fibers were modified by electrochemical oxidization using fatty alcohol polyoxyethylene ether phosphate (O3P, triethanolamine (TEOA and fatty alcohol polyoxyethylene ether ammonium phosphate (O3PNH4 as organic electrolyte respectively. Titration analysis, single fiber fracture strength measurement and field emission scanning electron microscopy (FE-SEM were used to evaluate the content of acidic functional group on the surface, mechanical properties and surface morphology of carbon fiber. The optimum process of electrochemical treatment obtained is at 50℃ for 2min and O3PNH4 (5%, mass fraction as the electrolyte with current density of 2A/g. In addition, the surface properties of modified carbon fibers were characterized by X-ray photoelectron spectroscopy (XPS and single fiber contact angle test. The results show that the hydrophilic acidic functional groups on the surface of carbon fiber which can enhance the surface energy are increased by the electrochemical oxidation using O3PNH4 as electrolyte, almost without any weakening to the mechanical properties of carbon fiber.

  14. Oxidative Stress, Inflammation, and DNA Damage Responses Elicited by Silver, Titanium Dioxide, and Cerium Oxide Nanomaterials

    Previous literature on the biological effects of engineered nanomaterials has focused largely on oxidative stress and inflammation endpoints without further investigating potential pathways. Here we examine time-sensitive biological response pathways affected by engineered nanoma...

  15. Echinacoside Induces Apoptosis in Human SW480 Colorectal Cancer Cells by Induction of Oxidative DNA Damages

    Liwei Dong

    2015-06-01

    Full Text Available Echinacoside is a natural compound with potent reactive oxygen species (ROS-scavenging and anti-oxidative bioactivities, which protect cells from oxidative damages. As cancer cells are often under intense oxidative stress, we therefore tested if Echinacoside treatment would promote cancer development. Surprisingly, we found that Echinacoside significantly inhibited the growth and proliferation of a panel of cancer cell lines. Treatment of the human SW480 cancer cells with Echinacoside resulted in marked apoptosis and cell cycle arrest, together with a significant increase in active caspase 3 and cleaved PARP, and upregulation of the G1/S-CDK blocker CDKN1B (p21. Interestingly, immunocytochemistry examination of drug-treated cancer cells revealed that Echinacoside caused a significant increase of intracellular oxidized guanine, 8-oxoG, and dramatic upregulation of the double-strand DNA break (DSB-binding protein 53BP1, suggesting that Echinacoside induced cell cycle arrest and apoptosis in SW480 cancer cells via induction of oxidative DNA damages. These results establish Echinacoside as a novel chemical scaffold for development of anticancer drugs.

  16. Solvent effects on hydrogen bonds in Watson-Crick, mismatched, and modified DNA base pairs

    Poater, Jordi; Swart, Marcel; Guerra, Celia Fonseca; Bickelhaupt, F. Matthias

    2012-01-01

    We have theoretically analyzed a complete series of Watson–Crick and mismatched DNA base pairs, both in gas phase and in solution. Solvation causes a weakening and lengthening of the hydrogen bonds between the DNA bases because of the stabilization of the lone pairs involved in these bonds. We have

  17. Pnc1p-mediated nicotinamide clearance modifies the epigenetic properties of rDNA silencing in Saccharomyces cerevisiae.

    McClure, Julie M; Gallo, Christopher M; Smith, Daniel L; Matecic, Mirela; Hontz, Robert D; Buck, Stephen W; Racette, Frances G; Smith, Jeffrey S

    2008-10-01

    The histone deacetylase activity of Sir2p is dependent on NAD(+) and inhibited by nicotinamide (NAM). As a result, Sir2p-regulated processes in Saccharomyces cerevisiae such as silencing and replicative aging are susceptible to alterations in cellular NAD(+) and NAM levels. We have determined that high concentrations of NAM in the growth medium elevate the intracellular NAD(+) concentration through a mechanism that is partially dependent on NPT1, an important gene in the Preiss-Handler NAD(+) salvage pathway. Overexpression of the nicotinamidase, Pnc1p, prevents inhibition of Sir2p by the excess NAM while maintaining the elevated NAD(+) concentration. This growth condition alters the epigenetics of rDNA silencing, such that repression of a URA3 reporter gene located at the rDNA induces growth on media that either lacks uracil or contains 5-fluoroorotic acid (5-FOA), an unusual dual phenotype that is reminiscent of telomeric silencing (TPE) of URA3. Despite the similarities to TPE, the modified rDNA silencing phenotype does not require the SIR complex. Instead, it retains key characteristics of typical rDNA silencing, including RENT and Pol I dependence, as well as a requirement for the Preiss-Handler NAD(+) salvage pathway. Exogenous nicotinamide can therefore have negative or positive impacts on rDNA silencing, depending on the PNC1 expression level.

  18. Fingerprinting DNA oxidation processes: IR characterization of the 5-methyl-2'-deoxycytidine radical cation.

    Bucher, Dominik B; Pilles, Bert M; Pfaffeneder, Toni; Carell, Thomas; Zinth, Wolfgang

    2014-02-24

    Methylated cytidine plays an important role as an epigenetic signal in gene regulation. Its oxidation products are assumed to be involved in active demethylation processes but also in damaging DNA. Here, we report the photochemical production of the 5-methyl-2'-deoxycytidine radical cation via a two-photon ionization process. The radical cation is detected by time-resolved IR spectroscopy and identified by band assignment using density functional theory calculations. Two final oxidation products are characterized with liquid chromatography coupled to mass spectrometry. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Role of surface chemistry in modified ACF (activated carbon fiber)-catalyzed peroxymonosulfate oxidation

    Yang, Shiying, E-mail: ysy@ouc.edu.cn [Key Laboratory of Marine Environment and Ecology, Ministry of Education, Qingdao 266100 (China); College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100 (China); Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering (MEGE), Qingdao 266100 (China); Li, Lei [College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100 (China); Xiao, Tuo [College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100 (China); China City Environment Protection Engineering Limited Company, Wuhan 430071 (China); Zheng, Di; Zhang, Yitao [College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100 (China)

    2016-10-15

    Highlights: • ACF can efficiently activate peroxymonosulfate to degrade organic pollutants. • Basic functional groups may mainly increase the adsorption capacity of ACF. • C1, N1, N2 have promoting effect on the ACF catalyzed PMS oxidation. • Modification by heat after nitric acid is also a way of ACF regeneration. - Abstract: A commercial activated carbon fiber (ACF-0) was modified by three different methods: nitration treatment (ACF-N), heat treatment (ACF-H) and heat treatment after nitration (ACF-NH), and the effects of textural and chemical properties on the ability of the metal-free ACF-catalyzed peroxymonosulfate (PMS) oxidation of Reactive Black 5 (RB5), an azo dye being difficultly adsorbed onto ACF, in aqueous solution were investigated in this work. Surface density of functional groups, surface area changes, surface morphology and the chemical state inside ACF samples were characterized by Boehm titration, N{sub 2} adsorption, scanning electron microscopy in couple with energy dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS), respectively. XPS spectra deconvolution was applied to figure out the importance of surface nitrogen-containing function groups. We found that π-π, pyridine and amine have promoting effect on the catalytic oxidation while the −NO{sub 2} has inhibitory effect on the ACF/PMS systems for RB5 destroy. Sustainability and renewability of the typical ACF-NH for catalytic oxidation of RB5 were also discussed in detail. Information about our conclusions are useful to control and improve the performance of ACF-catalyzed PMS oxidation for organic pollutants in wastewater treatment.

  20. Recognition of RNA by amide modified backbone nucleic acids: molecular dynamics simulations of DNA-RNA hybrids in aqueous solution.

    Nina, Mafalda; Fonné-Pfister, Raymonde; Beaudegnies, Renaud; Chekatt, Habiba; Jung, Pierre M J; Murphy-Kessabi, Fiona; De Mesmaeker, Alain; Wendeborn, Sebastian

    2005-04-27

    Thermodynamic and structural properties of a chemically modified DNA-RNA hybrid in which a phosphodiester linkage is replaced by a neutral amide-3 linkage (3'-CH(2)-CONH-5') were investigated using UV melting experiments, molecular dynamics simulations in explicit water, and continuum solvent models. van't Hoff analysis of the experimental UV melting curves suggests that the significant increase of the thermodynamic stability of a 15-mer DNA-RNA with seven alternated amide-3 modifications (+11 degrees C) is mainly due to an increased binding enthalpy. To further evaluate the origin in the observed affinities differences, the electrostatic contribution to the binding free energy was calculated by solving the Poisson-Boltzmann equation numerically. The nonelectrostatic contribution was estimated as the product of a hydrophobic surface tension coefficient and the surface area that is buried upon double strand formation. Structures were taken from 10 ns molecular dynamics simulations computed in a consistent fashion using explicit solvent, counterions, and the particle-mesh Ewald procedure. The present preliminary thermodynamic study suggests that the favorable binding free energy of the amide-3 DNA single strand to the complementary RNA is equally driven by electrostatic and nonpolar contributions to the binding compared to their natural analogues. In addition, molecular dynamics simulations in explicit water were performed on an amide-3 DNA single strand and the corresponding natural DNA. Results from the conformations cluster analysis of the simulated amide-3 DNA single strand ensembles suggest that the 25% of the population sampled within 10 ns has a pre-organized conformation where the sugar C3' endo pucker is favored at the 3'-flanking nucleotides. These structural and thermodynamic features contribute to the understanding of the observed increased affinities of the amide-3 DNA-RNA hybrids at the microscopic level.

  1. PNA-PEG modified silicon platforms as functional bio-interfaces for applications in DNA microarrays and biosensors.

    Cattani-Scholz, Anna; Pedone, Daniel; Blobner, Florian; Abstreiter, Gerhard; Schwartz, Jeffrey; Tornow, Marc; Andruzzi, Luisa

    2009-03-09

    The synthesis and characterization of two types of silicon-based biofunctional interfaces are reported; each interface bonds a dense layer of poly(ethylene glycol) (PEG(n)) and peptide nucleic acid (PNA) probes. Phosphonate self-assembled monolayers were derivatized with PNA using a maleimido-terminated PEG(45). Similarly, siloxane monolayers were functionalized with PNA using a maleimido-terminated PEG(45) spacer and were subsequently modified with a shorter methoxy-terminated PEG(12) ("back-filling"). The long PEG(45) spacer was used to distance the PNA probe from the surface and to minimize undesirable nonspecific adsorption of DNA analyte. The short PEG(12) "back-filler" was used to provide additional passivation of the surface against nonspecific DNA adsorption. X-ray photoelectron spectroscopic (XPS) analysis near the C 1s and N 1s ionization edges was done to characterize chemical groups formed in the near-surface region, which confirmed binding of PEG and PNA to the phosphonate and silane films. XPS also indicated that additional PEG chains were tethered to the surface during the back-filling process. Fluorescence hybridization experiments were carried out with complementary and noncDNA strands; both phosphonate and siloxane biofunctional surfaces were effective for hybridization of cDNA strands and significantly reduced nonspecific adsorption of the analyte. Spatial patterns were prepared by polydimethylsiloxane (PDMS) micromolding on the PNA-functionalized surfaces; selective hybridization of fluorescently labeled DNA was shown at the PNA functionalized regions, and physisorption at the probe-less PEG-functionalized regions was dramatically reduced. These results show that PNA-PEG derivatized phosphonate monolayers hold promise for the smooth integration of device surface chemistry with semiconductor technology for the fabrication of DNA biosensors. In addition, our results confirm that PNA-PEG derivatized self-assembled carboxyalkylsiloxane films are

  2. Surface-modified reduced graphene oxide electrodes for capacitors by ionic liquids and their electrochemical properties

    Kim, Jieun; Kim, Seok

    2014-01-01

    Highlights: • Reduced graphene oxide surface was modified by introduction of ionic liquids. • Microstructure and capacitance of modified electrode were dependent on the ionic liquids contents. • Modification gives electrode better charge transport and higher specific capacitance. • Modified electrode showed the better capacitive performance such as rate capability and cycle stability. - Abstract: In this work, reduced graphene oxide (rGO)/ionic liquids (IL) composites with different weight ratios of IL to rGO were synthesized by a simple method. In these composites, IL contributed to the exfoliation of rGO sheets and to the improvement of the electrochemical properties of the resulting composites by enhancing the ion diffusion and charge transport. The structure of the composites was examined by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The TEM images showed that IL was coated on the surface of rGO in a translucent manner. The electrochemical analysis of the prepared composites was carried out by performing cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS). Among the prepared composites, the one with a weight ratio of rGO to IL of 1:7 showed the highest specific capacitance of 147.5 F g −1 at a scan rate of 10 mV s −1 . In addition, the rate capability and cycle performance of the composites were enhanced compared to pristine rGO. These enhanced properties make the composites suitable as electrode materials for the better performance supercapacitors

  3. Voltammetric behavior of osmium-labeled DNA at mercury meniscus-modified solid amalgam electrodes. Detecting DNA hybridization

    Josypčuk, Bohdan; Fojta, Miroslav; Havran, Luděk; Heyrovský, Michael; Paleček, Emil

    2006-01-01

    Roč. 18, č. 2 (2006), s. 186-194 ISSN 1040-0397 R&D Projects: GA MPO 1H-PK/42; GA AV ČR IAA4004402; GA AV ČR KJB4004302; GA AV ČR IBS5004355 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z50040507 Keywords : voltammetry * solid amalgam electrodes * DNA-osmium complex * hybridization * catalytic hydrogen evolution Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.444, year: 2006

  4. Enhanced performance of dye-sensitized solar cells using gold nanoparticles modified fluorine tin oxide electrodes

    Zhang Dingwen; Shen Jie; Huang Sumei; Wang Milton; Brolo, Alexandre G; Li Xiaodong

    2013-01-01

    We have investigated plasmon-assisted energy conversion in dye-sensitized solar cells (DSCs) applying gold nanoparticles (NPs) modified fluorine tin oxide (FTO) electrodes. A series of Au NPs with different sizes (15-80 nm) were synthesized and immobilized onto FTO glass slides. Photoanodes were prepared on these Au modified FTO substrates using P25 TiO 2 powders and by the screen-printing method. The size effects of Au NPs on the photovoltaic performance of the formed DSCs were investigated systematically. Structural and photoelectrochemical properties of the formed photoanodes were examined by field emission scanning electron microscopy and electrochemical impedance spectroscopy. It was found that the energy conversion efficiency of the DSC was highly dependent on the Au particle size. When the particle size was not greater than 60 nm, the DSC based on the Au NP-FTO composite electrode showed a higher short-circuit current density and better photovoltaic (PV) performance than the cell based on the bare FTO. The best cell was achieved using 25 nm sized Au NPs modified FTO. It exhibited a conversion efficiency of 6.69%, which was 15% higher than that of DSCs without Au NPs. The related PV performance enhancement mechanisms, photoelectrochemical processes and surface-plasmon resonances in DSCs with Au nanostructures are analysed and discussed.

  5. Polyrhodanine modified anodic aluminum oxide membrane for heavy metal ions removal.

    Song, Jooyoung; Oh, Hyuntaek; Kong, Hyeyoung; Jang, Jyongsik

    2011-03-15

    Polyrhodanine was immobilized onto the inner surface of anodic aluminum oxide (AAO) membrane via vapor deposition polymerization method. The polyrhodanine modified membrane was applied to remove heavy metal ions from aqueous solution because polyrhodanine could be coordinated with specific metal ions. Several parameters such as initial metal concentration, contact time and metal species were evaluated systematically for uptake efficiencies of the fabricated membrane under continuous flow condition. Adsorption isotherms of Hg(II) ion on the AAO-polyrhodanine membrane were analyzed with Langmuir and Freundlich isotherm models. The adsorption rate of Hg(II) ion on the membrane was obeyed by a pseudo-second order equation, indicating the chemical adsorption. The maximum removal capacity of Hg(II) ion onto the fabricated membrane was measured to be 4.2 mmol/g polymer. The AAO-polyrhodanine membrane had also remarkable uptake performance toward Ag(I) and Pb(II) ions. Furthermore, the polyrhodanine modified membrane could be recycled after recovery process. These results demonstrated that the polyrhodanine modified AAO membrane provided potential applications for removing the hazardous heavy metal ions from wastewater. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. The oxidative DNA glycosylases of Mycobacterium tuberculosis exhibit different substrate preferences from their Escherichia coli counterparts.

    Guo, Yin; Bandaru, Viswanath; Jaruga, Pawel; Zhao, Xiaobei; Burrows, Cynthia J; Iwai, Shigenori; Dizdaroglu, Miral; Bond, Jeffrey P; Wallace, Susan S

    2010-02-04

    The DNA glycosylases that remove oxidized DNA bases fall into two general families: the Fpg/Nei family and the Nth superfamily. Based on protein sequence alignments, we identified four putative Fpg/Nei family members, as well as a putative Nth protein in Mycobacterium tuberculosis H37Rv. All four Fpg/Nei proteins were successfully overexpressed using a bicistronic vector created in our laboratory. The MtuNth protein was also overexpressed in soluble form. The substrate specificities of the purified enzymes were characterized in vitro with oligodeoxynucleotide substrates containing single lesions. Some were further characterized by gas chromatography/mass spectrometry (GC/MS) analysis of products released from gamma-irradiated DNA. MtuFpg1 has substrate specificity similar to that of EcoFpg. Both EcoFpg and MtuFpg1 are more efficient at removing spiroiminodihydantoin (Sp) than 7,8-dihydro-8-oxoguanine (8-oxoG). However, MtuFpg1 shows a substantially increased opposite base discrimination compared to EcoFpg. MtuFpg2 contains only the C-terminal domain of an Fpg protein and has no detectable DNA binding activity or DNA glycosylase/lyase activity and thus appears to be a pseudogene. MtuNei1 recognizes oxidized pyrimidines on both double-stranded and single-stranded DNA and exhibits uracil DNA glycosylase activity. MtuNth recognizes a variety of oxidized bases, including urea, 5,6-dihydrouracil (DHU), 5-hydroxyuracil (5-OHU), 5-hydroxycytosine (5-OHC) and methylhydantoin (MeHyd). Both MtuNei1 and MtuNth excise thymine glycol (Tg); however, MtuNei1 strongly prefers the (5R) isomers, whereas MtuNth recognizes only the (5S) isomers. MtuNei2 did not demonstrate activity in vitro as a recombinant protein, but like MtuNei1 when expressed in Escherichia coli, it decreased the spontaneous mutation frequency of both the fpg mutY nei triple and nei nth double mutants, suggesting that MtuNei2 is functionally active in vivo recognizing both guanine and cytosine oxidation products

  7. Simultaneous oxidation and adsorption of As(III) from water by cerium modified chitosan ultrafine nanobiosorbent

    Zhang, Lingfan [School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237 (China); Research Center of Analysis and Test, East China University of Science and Technology, Shanghai 200237 (China); Zhu, Tianyi [School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237 (China); Liu, Xin, E-mail: liuxin@ecust.edu.cn [School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zhang, Wenqing, E-mail: zhwqing@ecust.edu.cn [School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237 (China)

    2016-05-05

    Highlights: • A novel ultrafine nanobiosorbent of cerium modified chitosan (Ce-CNB) was prepared. • The Ce-CNB possessed properties for simultaneous oxidation and adsorption As(III). • Adsorption of As(III) by Ce-CNB was in high efficiency. • Mechanisms for As(III) adsorption on Ce-CNB were elucidated. - Abstract: Since most existing arsenic removal adsorbents are difficult to effectively remove arsenite (As(III)), an urgent need is to develop an efficient adsorbent for removing As(III) from contaminated water. In this study, a novel ultrafine nanobiosorbent of cerium modified chitosan (Ce-CNB) with simultaneous oxidation and adsorption As(III) performance has been successfully developed. The resulting Ce-CNB with or without As(III) adsorption was characterized by FTIR, XRD, SEM, EDS, TEM, EMI and XPS analysis. Batch of adsorption experiments were performed to investigate the effects of various conditions on the As(III) adsorption. The adsorption behaviors were well described by the Langmuir isotherm and the pseudo-second-order kinetic model, with the maximum adsorption capacities of 57.5 mg g{sup −1}. The adsorption mechanisms for As(III) were (i) formed monodentate and bidentate complexes between hydroxyl groups and arsenite; and (ii) partial As(III) oxidized to As(V) followed by simultaneously adsorbed on the surface of Ce-CNB. This novel nanocomposite can be reused while maintaining a high removal efficiency and can be applied to treat 5.8 L of As(III)-polluted water with the effluent concentration lower than the World Health Organization standard, which suggests its great potential to remove As(III) from contaminated water.

  8. Shape-dependent bactericidal activity of copper oxide nanoparticle mediated by DNA and membrane damage

    Laha, Dipranjan; Pramanik, Arindam; Laskar, Aparna; Jana, Madhurya; Pramanik, Panchanan; Karmakar, Parimal

    2014-01-01

    Highlights: • Spherical and sheet shaped copper oxide nanoparticles were synthesized. • Physical characterizations of these nanoparticles were done by TEM, DLS, XRD, FTIR. • They showed shape dependent antibacterial activity on different bacterial strain. • They induced both membrane damage and ROS mediated DNA damage in bacteria. - Abstract: In this work, we synthesized spherical and sheet shaped copper oxide nanoparticles and their physical characterizations were done by the X-ray diffraction, fourier transform infrared spectroscopy, transmission electron microscopy and dynamic light scattering. The antibacterial activity of these nanoparticles was determined on both gram positive and gram negative bacterial. Spherical shaped copper oxide nanoparticles showed more antibacterial property on gram positive bacteria where as sheet shaped copper oxide nanoparticles are more active on gram negative bacteria. We also demonstrated that copper oxide nanoparticles produced reactive oxygen species in both gram negative and gram positive bacteria. Furthermore, they induced membrane damage as determined by atomic force microscopy and scanning electron microscopy. Thus production of and membrane damage are major mechanisms of the bactericidal activity of these copper oxide nanoparticles. Finally it was concluded that antibacterial activity of nanoparticles depend on physicochemical properties of copper oxide nanoparticles and bacterial strain

  9. Shape-dependent bactericidal activity of copper oxide nanoparticle mediated by DNA and membrane damage

    Laha, Dipranjan; Pramanik, Arindam [Department of Life Science and Biotechnology, Jadavpur University, 188, Raja S C Mallick Road, Kolkata 700032 (India); Laskar, Aparna [CSIR-Indian Institute of Chemical Biology, Kolkata 700032 (India); Jana, Madhurya [Department of Life Science and Biotechnology, Jadavpur University, 188, Raja S C Mallick Road, Kolkata 700032 (India); Pramanik, Panchanan [Department of Chemistry, Indian Institute of Technology, Kharagpur 721302 (India); Karmakar, Parimal, E-mail: pkarmakar_28@yahoo.co.in [Department of Life Science and Biotechnology, Jadavpur University, 188, Raja S C Mallick Road, Kolkata 700032 (India)

    2014-11-15

    Highlights: • Spherical and sheet shaped copper oxide nanoparticles were synthesized. • Physical characterizations of these nanoparticles were done by TEM, DLS, XRD, FTIR. • They showed shape dependent antibacterial activity on different bacterial strain. • They induced both membrane damage and ROS mediated DNA damage in bacteria. - Abstract: In this work, we synthesized spherical and sheet shaped copper oxide nanoparticles and their physical characterizations were done by the X-ray diffraction, fourier transform infrared spectroscopy, transmission electron microscopy and dynamic light scattering. The antibacterial activity of these nanoparticles was determined on both gram positive and gram negative bacterial. Spherical shaped copper oxide nanoparticles showed more antibacterial property on gram positive bacteria where as sheet shaped copper oxide nanoparticles are more active on gram negative bacteria. We also demonstrated that copper oxide nanoparticles produced reactive oxygen species in both gram negative and gram positive bacteria. Furthermore, they induced membrane damage as determined by atomic force microscopy and scanning electron microscopy. Thus production of and membrane damage are major mechanisms of the bactericidal activity of these copper oxide nanoparticles. Finally it was concluded that antibacterial activity of nanoparticles depend on physicochemical properties of copper oxide nanoparticles and bacterial strain.

  10. Oxidative damage of mitochondrial and nuclear DNA induced by ionizing radiation in human hepatoblastoma cells

    Morales, Albert; Miranda, Merce; Sanchez-Reyes, Alberto; Biete, Alberto; Fernandez-Checa, Jose C.

    1998-01-01

    Purpose: Since reactive oxygen species (ROS) act as mediators of radiation-induced cellular damage, the aim of our studies was to determine the effects of ionizing radiation on the regulation of hepatocellular reduced glutathione (GSH), survival and integrity of nuclear and mitochondrial DNA (mtDNA) in human hepatoblastoma cells (Hep G2) depleted of GSH prior to radiation. Methods and Materials: GSH, oxidized glutathione (GSSG), and generation of ROS were determined in irradiated (50-500 cGy) Hep G2 cells. Clonogenic survival, nuclear DNA fragmentation, and integrity of mtDNA were assessed in cells depleted of GSH prior to radiation. Results: Radiation of Hep G2 cells (50-400 cGy) resulted in a dose-dependent generation of ROS, an effect accompanied by a decrease of reduced GSH, ranging from a 15% decrease for 50 cGy to a 25% decrease for 400 cGy and decreased GSH/GSSG from a ratio of 17 to a ratio of 7 for controls and from 16 to 6 for diethyl maleate (DEM)-treated cells. Depletion of GSH prior to radiation accentuated the increase of ROS by 40-50%. The depletion of GSH by radiation was apparent in different subcellular sites, being particularly significant in mitochondria. Furthermore, depletion of nuclear GSH to 50-60% of initial values prior to irradiation (400 cGy) resulted in DNA fragmentation and apoptosis. Consequently, the survival of Hep G2 to radiation was reduced from 25% of cells not depleted of GSH to 10% of GSH-depleted cells. Fitting the survival rate of cells as a function of GSH using a theoretical model confirmed cellular GSH as a key factor in determining intrinsic sensitivity of Hep G2 cells to radiation. mtDNA displayed an increased susceptibility to the radiation-induced loss of integrity compared to nuclear DNA, an effect that was potentiated by GSH depletion in mitochondria (10-15% intact mtDNA in GSH-depleted cells vs. 25-30% of repleted cells). Conclusion: GSH plays a critical protective role in maintaining nuclear and mtDNA functional

  11. DNA methyltransferase 1-targeting miRNA-148aof dairymilk: apotential bioactive modifier of thehumanepigenome

    Bodo C. Melnik

    2017-09-01

    Full Text Available Background: The perception of milk has changed from a “simple food” to a more sophisticated bioactive functional signaling system that promotes mTORC1-driven postnatal anabolism, growth, and development of the newborn infant. Accumulating evidence supports the view that milk´s miRNAs significantly contribute to these processes. The most abundant miRNA of milk found in milk fat and milk exosomes is miRNA-148a, which targets DNA methyltransferase 1 (DNMT1, a pivotal epigenetic regulator that suppresses transcription. Furthermore, milk-derived miRNA-125b, miRNA-30d, and miRNA-25 target TP53, the guardian of the genome that interacts with DNMT1 and regulates metabolism, cell kinetics, and apoptosis. Thus, the question arose whether cow´s milk-derived miRNAs may modify epigenetic regulation of the human milk consumer. Methods: To understand the potential impact of dairy milk consumption on human epigenetics, we have analyzed all relevant research-based bioinformatics data related to milk, milk miRNAs, epigenetic regulation, and lactation performance with special attention to bovine miRNAs that modify gene expression of DNA methyltransferase 1 (DNMT1 and p53 (TP53, the two guardians of the mammalian genome. By means of translational research and comparative functional genomics, we investigated the potential impact of cow´s milk miRNAs on epigenetic regulation of human DNMT1, TP53, FOXP3, and FTO, which are critically involved in immunologic and metabolic programming respectively. miRNA sequences have been obtained from mirbase.org. miRNA-target site prediction has been performed using TargetScan release 7.0. Results: The most abundant miRNA of cow´s milk is miRNA-148a, which represents more than 10% of all miRNAs of cow´s milk, survives pasteurization and refrigerated storage. The seed sequence of human and bovine miRNA-148a-3p is identical. Furthermore, human and bovine DNMT1 mRNA share 88% identity. The miRNA-148a 7mer seed is conserved in

  12. Effects of environmental pollution on endogenous oxidative DNA damage in humans

    Singh, R.; Kaur, B.; Kalina, I.; Popov, T. A.; Georgieva, T.; Garte, S.; Binková, Blanka; Šrám, Radim; Taioli, E.; Farmer, P. B.

    2007-01-01

    Roč. 620, - (2007), s. 71-82 ISSN 0027-5107 Grant - others:EU(NO) 2000 -00091; EU(NO) G0100873 Institutional research plan: CEZ:AV0Z50390512 Source of funding: R - rámcový projekt EK ; R - rámcový projekt EK Keywords : oxidative DNA damage * polycyclic aromatic hydrocarbons * -oxo-deoxyguanosine Subject RIV: DN - Health Impact of the Environment Quality Impact factor: 4.159, year: 2007

  13. DNA damage and defence gene expression after oxidative stress induced by x-rays and diesel exhaust particles

    Risom, Lotte

    2004-01-01

    Particulate air pollution is one the most important environmental health factors for people living in cities. Especially the exhaust particles from traffic are possible causes for cancer and cardiopulmonary diseases. The aim of this thesis was to characterize the health effects of diesel exhaust particles (DEP) by inducing oxidative stress and analyse the underlying mechanisms. Methods for determining oxidative stress, DNA damage, and gene expression were validated and calibrated in lung tissue by studying the dose response relations after ionizing radiation. The study showed the feasibility of partial-body x-ray irradiation as an in vivo model for induction and repair of oxidative DNA damage, of DNA repair enzymes expression, and antioxidant defense genes. A 'nose-only' mouse model for inhalation of ultra-fine particles showed that particles induce oxidative DNA damage in lung tissue and in bronchoalveolar lavage cells. The exposure increased the expression of HO-1 mRNA and oxoguanine DNA glycosylase OGG1 mRNA. The levels of 8-oxodG and OGG1 mRNA were mirror images. Colon and liver were analysed after administration of DEP in the diet with or without increasing doses of sucrose. This study indicated that DEP induces DNA adducts and oxidative stress through formation of DNA strand breaks, DNA repair enzyme expression, apoptosis, and protein oxidisation in colon and liver at relatively low exposure doses. The thesis is based on four published journal articles. (ln)

  14. DNA damage and defence gene expression after oxidative stress induced by x-rays and diesel exhaust particles

    Risom, Lotte

    2004-07-01

    Particulate air pollution is one the most important environmental health factors for people living in cities. Especially the exhaust particles from traffic are possible causes for cancer and cardiopulmonary diseases. The aim of this thesis was to characterize the health effects of diesel exhaust particles (DEP) by inducing oxidative stress and analyse the underlying mechanisms. Methods for determining oxidative stress, DNA damage, and gene expression were validated and calibrated in lung tissue by studying the dose response relations after ionizing radiation. The study showed the feasibility of partial-body x-ray irradiation as an in vivo model for induction and repair of oxidative DNA damage, of DNA repair enzymes expression, and antioxidant defense genes. A 'nose-only' mouse model for inhalation of ultra-fine particles showed that particles induce oxidative DNA damage in lung tissue and in bronchoalveolar lavage cells. The exposure increased the expression of HO-1 mRNA and oxoguanine DNA glycosylase OGG1 mRNA. The levels of 8-oxodG and OGG1 mRNA were mirror images. Colon and liver were analysed after administration of DEP in the diet with or without increasing doses of sucrose. This study indicated that DEP induces DNA adducts and oxidative stress through formation of DNA strand breaks, DNA repair enzyme expression, apoptosis, and protein oxidisation in colon and liver at relatively low exposure doses. The thesis is based on four published journal articles. (ln)

  15. Effect of complex polyphenols and tannins from red wine (WCPT) on chemically induced oxidative DNA damage in the rat.

    Casalini, C; Lodovici, M; Briani, C; Paganelli, G; Remy, S; Cheynier, V; Dolara, P

    1999-08-01

    Flavonoids are polyphenolic antioxidants occurring in vegetables and fruits as well as beverages such as tea and wine which have been thought to influence oxidative damage. We wanted to verify whether a complex mixture of wine tannins (wine complex polyphenols and tannins, WCPT) prevent chemically-induced oxidative DNA damage in vivo. Oxidative DNA damage was evaluated by measuring the ratio of 8-hydroxy-2'-deoxyguanosine (80HdG)/ 2-deoxyguanosine (2dG) x 10(-6) in hydrolyzed DNA using HPLC coupled with electrochemical and UV detectors. We treated rats with WCPT (57 mg/kg p.o.) for 14 d, a dose 10-fold higher than what a moderate wine drinker would be exposed to. WCPT administration significantly reduced the ratio of 80HdG/2dG x 10(-6) in liver DNA obtained from rats treated with 2-nitropropane (2NP) relative to controls administered 2NP only (33. 3 +/- 2.5 vs. 44.9 +/- 3.2 x 10(-6) 2dG; micro +/- SE; p<0.05). On the contrary, pretreatment with WCPT for 10 d did not protect the colon mucosa from oxidative DNA damage induced by 1, 2-dimethylhydrazine (DMH). 2NP and DMH are hepatic and colon carcinogens, respectively, capable of inducing oxidative DNA damage. WCPT have protective action against some types of chemically-induced oxidative DNA damage in vivo.

  16. Watson-Crick Base Pair Radical Cation as a Model for Oxidative Damage in DNA.

    Feketeová, Linda; Chan, Bun; Khairallah, George N; Steinmetz, Vincent; Maitre, Philippe; Radom, Leo; O'Hair, Richard A J

    2017-07-06

    The deleterious cellular effects of ionizing radiation are well-known, but the mechanisms causing DNA damage are poorly understood. The accepted molecular events involve initial oxidation and deprotonation at guanine sites, triggering hydrogen atom abstraction reactions from the sugar moieties, causing DNA strand breaks. Probing the chemistry of the initially formed radical cation has been challenging. Here, we generate, spectroscopically characterize, and examine the reactivity of the Watson-Crick nucleobase pair radical cation in the gas phase. We observe rich chemistry, including proton transfer between the bases and propagation of the radical site in deoxyguanosine from the base to the sugar, thus rupturing the sugar. This first example of a gas-phase model system providing molecular-level details on the chemistry of an ionized DNA base pair paves the way toward a more complete understanding of molecular processes induced by radiation. It also highlights the role of radical propagation in chemistry, biology, and nanotechnology.

  17. Imidazolium Ionic Liquid Modified Graphene Oxide: As a Reinforcing Filler and Catalyst in Epoxy Resin

    Qing Lyu

    2017-09-01

    Full Text Available Surface modification of graphene oxide (GO is one of the most important issues to produce high performance GO/epoxy composites. In this paper, the imidazole ionic liquid (IMD-Si was introduced onto the surface of GO sheets by a cheap and simple method, to prepare a reinforcing filler, as well as a catalyst in epoxy resin. The interlayer spacing of GO sheets was obviously increased by the intercalation of IMD-Si, which strongly facilitated the dispersibility of graphene oxide in organic solvents and epoxy matrix. The addition of 0.4 wt % imidazolium ionic liquid modified graphene oxide (IMD-Si@GO, yielded a 12% increase in flexural strength (141.3 MPa, a 26% increase in flexural modulus (4.69 GPa, and a 52% increase in impact strength (18.7 kJ/m2, compared to the neat epoxy. Additionally the IMD-Si@GO sheets could catalyze the curing reaction of epoxy resin-anhydride system significantly. Moreover, the improved thermal conductivities and thermal stabilities of epoxy composites filled with IMD-Si@GO were also demonstrated.

  18. Rheological Behaviour of a Bitumen Modified with Metal Oxides Obtained by Regeneration Processes

    Tullio Giuffrè

    2018-02-01

    Full Text Available Nowadays, one important challenge is to demonstrate an innovative and integrated approach for the sustainable construction of roads considering the whole life cycle of the infrastructure. Road pavements with multiple asphalt layers generally undergo prolonged environmental exposure and the alternation between solar irradiation and low temperatures. As a result, relaxation or progressive removal of the material with a negative impact on the resistance to plastic deformation occur, also leading to the formation of slits and to dimensional variations, which are commonly defined as thermal cracking. This suggests the use of suitable bitumen modifiers. For these, important parameters are the optimal mixing time and mixing temperature, in order to reduce problems related to the stability of the bitumen. Therefore, the behaviour, upon changing the temperature, of bituminous mixtures containing (as fillers a series of metal oxides coming, as secondary products, from spent acid solutions regeneration processes, was investigated. This is intended in order to recover and reuse those otherwise dangerous wastes coming from several industrial (especially, metallurgical processes. The study was aimed at evaluating the properties of bituminous blends by performing rheological tests under dynamic shear regime. More specifically, five different bitumen matrices were prepared (70/100 bitumen and blends with metal oxides and/or SBS copolymer. Results showed that the addition of iron oxides leads to an increase of the softening point and the complex modulus. The increase is even more emphasized when SBS is added to the blend.

  19. Polypyrrole Coated Cellulosic Substrate Modified by Copper Oxide as Electrode for Nitrate Electroreduction

    Hamam, A.; Oukil, D.; Dib, A.; Hammache, H.; Makhloufi, L.; Saidani, B.

    2015-08-01

    The aim of this work is to synthesize polypyrrole (PPy) films on nonconducting cellulosic substrate and modified by copper oxide particles for use in the nitrate electroreduction process. Firstly, the chemical polymerization of polypyrrole onto cellulosic substrate is conducted by using FeCl3 as an oxidant and pyrrole as monomer. The thickness and topography of the different PPy films obtained were estimated using a profilometer apparatus. The electrochemical reactivity of the obtained electrodes was tested by voltamperometry technique and electrochemical impedance spectroscopy. Secondly, the modification of the PPy film surface by incorporation of copper oxide particles is conducted by applying a galvanostatic procedure from a CuCl2 solution. The SEM, EDX and XRD analysis showed the presence of CuO particles in the polymer films with dimensions less than 50 nm. From cyclic voltamperometry experiments, the composite activity for the nitrate electroreduction reaction was evaluated and the peak of nitrate reduction is found to vary linearly with initial nitrate concentration.

  20. Colloidally stable surface-modified iron oxide nanoparticles: Preparation, characterization and anti-tumor activity

    Macková, Hana [Institute of Macromolecular Chemistry, AS CR, Heyrovsky Sq. 2, 162 06 Prague 6 (Czech Republic); Horák, Daniel, E-mail: horak@imc.cas.cz [Institute of Macromolecular Chemistry, AS CR, Heyrovsky Sq. 2, 162 06 Prague 6 (Czech Republic); Donchenko, Georgiy Viktorovich; Andriyaka, Vadim Ivanovich; Palyvoda, Olga Mikhailovna; Chernishov, Vladimir Ivanovich [Palladin Institute of Biochemistry, NASU, 9 Leontovich St., 01601 Kiev (Ukraine); Chekhun, Vasyl Fedorovich; Todor, Igor Nikolaevich [R. E. Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology, NASU, 45 Vasylkivska St., 03022 Kiev (Ukraine); Kuzmenko, Oleksandr Ivanovich [Palladin Institute of Biochemistry, NASU, 9 Leontovich St., 01601 Kiev (Ukraine)

    2015-04-15

    Maghemite (γ-Fe{sub 2}O{sub 3}) nanoparticles were obtained by co-precipitation of Fe(II) and Fe(III) chlorides and subsequent oxidation with sodium hypochlorite and coated with poly(N,N-dimethylacrylamide-co-acrylic acid) [P(DMAAm-AA)]. They were characterized by a range of methods including transmission electron microscopy (TEM), elemental analysis, dynamic light scattering (DLS) and zeta potential measurements. The effect of superparamagnetic P(DMAAm-AA)-γ-Fe{sub 2}O{sub 3} nanoparticles on oxidation of blood lipids, glutathione and proteins in blood serum was detected using 2-thiobarbituric acid and the ThioGlo fluorophore. Finally, mice received magnetic nanoparticles administered per os and the antitumor activity of the particles was tested on Lewis lung carcinoma (LLC) in male mice line C57BL/6 as an experimental in vivo metastatic tumor model; the tumor size was measured and the number of metastases in lungs was determined. Surface-modified γ-Fe{sub 2}O{sub 3} nanoparticles showed higher antitumor and antimetastatic activities than commercial CuFe{sub 2}O{sub 4} particles and the conventional antitumor agent cisplatin. - Highlights: • Maghemite nanoparticles were prepared and characterized. • Poly(N,N-dimethylacrylamide-co-acrylic acid) coating was synthetized. • Blood lipid, glutathione and protein peroxidation/oxidation was determined. • Antitumor effect of coated particles on Lewis lung carcinoma in mice was observed.

  1. Synthesis of oxidation resistant lead nanoparticle films by modified pulsed laser ablation

    Shin, Eunsung; Murray, P. Terrence; Subramanyam, Guru; Malik, Hans K.; Schwartz, Kenneth L. [Research Institute, University of Dayton, Dayton, OH 45469-0170 (United States); Research Institute, University of Dayton, Dayton, OH 45469-0170, USA and Graduate Materials Engineering, University of Dayton, Dayton, OH 45469-0240 (United States); Department of Electrical and Computer Engineering, University of Dayton, Dayton, OH 45469-0232 (United States); Northrop Grumman Electronic Systems, Linthicum, MD 21090 (United States)

    2012-07-30

    Thin layers of lead nanoparticles have been produced by a modified pulsed laser ablation (PLA) process in which smaller nanoparticles were swept out of the ablation chamber by a stream of flowing Ar. Large ({mu}m-sized) particles, which are usually deposited during the standard PLA process, were successfully eliminated from the deposit. The nanoparticles deposited on room temperature substrates were well distributed, and the most probable particle diameter was in the order of 30 nm. Since lead is highly reactive, the nanoparticles formed in Ar were quickly oxidized upon exposure to air. A small partial pressure of H{sub 2}S gas was subsequently added to the effluent, downstream from the ablation chamber, and this resulted in the formation of nanoparticle deposits that were surprisingly oxidation resistant. The properties of the nanoparticle films (as determined by transmission electron microscopy, scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and conductivity measurements) are reported, and the mechanism of the oxidation retardation process is discussed.

  2. Altering CO2 during reperfusion of ischemic cardiomyocytes modifies mitochondrial oxidant injury.

    Lavani, Romeen; Chang, Wei-Tien; Anderson, Travis; Shao, Zuo-Hui; Wojcik, Kimberly R; Li, Chang-Qing; Pietrowski, Robert; Beiser, David G; Idris, Ahamed H; Hamann, Kimm J; Becker, Lance B; Vanden Hoek, Terry L

    2007-07-01

    species. Altering CO2 content during reperfusion can significantly affect myocardial postresuscitation injury, in part by modifying mitochondrial oxidants and NO synthase-induced NO production.

  3. Skin photoprotection by natural polyphenols: Anti-inflammatory, anti-oxidant and DNA repair mechanisms

    Nichols, Joi A.; Katiyar, Santosh K.

    2009-01-01

    Epidemiological, clinical and laboratory studies have implicated solar ultraviolet (UV) radiation in various skin diseases including premature aging of the skin and melanoma and nonmelanoma skin cancers. Chronic UV radiation exposure-induced skin diseases or skin disorders are caused by the excessive induction of inflammation, oxidative stress and DNA damage, etc.. The use of chemopreventive agents, such as plant polyphenols, to inhibit these events in UV-exposed skin is gaining attention. Chemoprevention refers to the use of agents that can inhibit, reverse, or retard the process of these harmful events in the UV-exposed skin. A wide variety of polyphenols or phytochemicals, most of which are dietary supplements, have been reported to possess substantial skin photoprotective effects. This review article summarizes the photoprotective effects of some selected polyphenols, such as green tea polyphenols, grape seed proanthocyanidins, resveratrol, silymarin and genistein, on UV-induced skin inflammation, oxidative stress, and DNA damage, etc., with a focus on mechanisms underlying the photoprotective effects of these polyphenols. The laboratory studies conducted in animal models, suggest that these polyphenols have the ability to protect the skin from the adverse effects of UV radiation, including the risk of skin cancers. It is suggested that polyphenols may favorably supplement sunscreens protection, and may be useful for skin diseases associated with solar UV radiation-induced inflammation, oxidative stress and DNA damage. PMID:19898857

  4. Nitrogen gas plasma treatment of bacterial spores induces oxidative stress that damages the genomic DNA.

    Sakudo, Akikazu; Toyokawa, Yoichi; Nakamura, Tetsuji; Yagyu, Yoshihito; Imanishi, Yuichiro

    2017-01-01

    Gas plasma, produced by a short high‑voltage pulse generated from a static induction thyristor power supply [1.5 kilo pulse/sec (kpps)], was demonstrated to inactivate Geobacillus stearothermophilus spores (decimal reduction time at 15 min, 2.48 min). Quantitative polymerase chain reaction and enzyme‑linked immunosorbent assays further indicated that nitrogen gas plasma treatment for 15 min decreased the level of intact genomic DNA and increased the level of 8-hydroxy-2'-deoxyguanosine, a major product of DNA oxidation. Three potential inactivation factors were generated during operation of the gas plasma instrument: Heat, longwave ultraviolet-A and oxidative stress (production of hydrogen peroxide, nitrite and nitrate). Treatment of the spores with hydrogen peroxide (3x2‑4%) effectively inactivated the bacteria, whereas heat treatment (100˚C), exposure to UV-A (75‑142 mJ/cm2) and 4.92 mM peroxynitrite (•ONOO‑), which is decomposed into nitrite and nitrate, did not. The results of the present study suggest the gas plasma treatment inactivates bacterial spores primarily by generating hydrogen peroxide, which contributes to the oxidation of the host genomic DNA.

  5. Increased Chromosomal and Oxidative DNA Damage in Patients with Multinodular Goiter and Their Association with Cancer

    Hamiyet Donmez-Altuntas

    2017-01-01

    Full Text Available Thyroid nodules are a common clinical problem worldwide. Although thyroid cancer accounts for a small percentage of thyroid nodules, the majority are benign. 8-Hydroxy-2′-deoxyguanosine (8-OHdG levels are a marker of oxidative stress and play a key role in the initiation and development of a range of diseases and cancer types. This study evaluates cytokinesis-block micronucleus cytome (CBMN-cyt assay parameters and plasma 8-OHdG levels and their association with thyroid nodule size and thyroid hormones in patients with multinodular goiter. The study included 32 patients with multinodular goiter and 18 age- and sex-matched healthy controls. CBMN-cyt assay parameters in peripheral blood lymphocytes of patients with multinodular goiter and controls were evaluated, and plasma 8-OHdG levels were measured. The micronucleus (MN frequency (chromosomal DNA damage, apoptotic and necrotic cells (cytotoxicity, and plasma 8-OHdG levels (oxidative DNA damage were significantly higher among patients with multinodular goiter. Our study is the first report of increased chromosomal and oxidative DNA damage in patients with multinodular goiter, which may predict an increased risk of thyroid cancer in these patients. MN frequency and plasma 8-OHdG levels may be markers of the carcinogenic potential of multinodular goiters and could be used for early detection of different cancer types, including thyroid cancer.

  6. Evaluation of Cassia tora Linn. against oxidative stress-induced DNA and cell membrane damage

    R Sunil Kumar

    2017-01-01

    Full Text Available Objective: The present study aims to evaluate antioxidants and protective role of Cassia tora Linn. against oxidative stress-induced DNA and cell membrane damage. Materials and Methods: The total and profiles of flavonoids were identified and quantified through reversed-phase high-performance liquid chromatography. In vitro antioxidant activity was determined using standard antioxidant assays. The protective role of C. tora extracts against oxidative stress-induced DNA and cell membrane damage was examined by electrophoretic and scanning electron microscopic studies, respectively. Results: The total flavonoid content of CtEA was 106.8 ± 2.8 mg/g d.w.QE, CtME was 72.4 ± 1.12 mg/g d.w.QE, and CtWE was 30.4 ± 0.8 mg/g d.w.QE. The concentration of flavonoids present in CtEA in decreasing order: quercetin >kaempferol >epicatechin; in CtME: quercetin >rutin >kaempferol; whereas, in CtWE: quercetin >rutin >kaempferol. The CtEA inhibited free radical-induced red blood cell hemolysis and cell membrane morphology better than CtME as confirmed by a scanning electron micrograph. CtEA also showed better protection than CtME and CtWE against free radical-induced DNA damage as confirmed by electrophoresis. Conclusion: C. tora contains flavonoids and inhibits oxidative stress and can be used for many health benefits and pharmacotherapy.

  7. Measuring oxidative damage to DNA and its repair with the comet assay.

    Collins, Andrew R

    2014-02-01

    Single cell gel electrophoresis, or the comet assay, was devised as a sensitive method for detecting DNA strand breaks, at the level of individual cells. A simple modification, incorporating a digestion of DNA with a lesion-specific endonuclease, makes it possible to measure oxidised bases. With the inclusion of formamidopyrimidine DNA glycosylase to recognise oxidised purines, or Nth (endonuclease III) to detect oxidised pyrimidines, the comet assay has been used extensively in human biomonitoring to monitor oxidative stress, usually in peripheral blood mononuclear cells. There is evidence to suggest that the enzymic approach is more accurate than chromatographic methods, when applied to low background levels of base oxidation. However, there are potential problems of over-estimation (because the enzymes are not completely specific) or under-estimation (failure to detect lesions that are close together). Attempts have been made to improve the inter-laboratory reproducibility of the comet assay. In addition to measuring DNA damage, the assay can be used to monitor the cellular or in vitro repair of strand breaks or oxidised bases. It also has applications in assessing the antioxidant status of cells. In its various forms, the comet assay is now an invaluable tool in human biomonitoring and genotoxicity testing. This article is part of a Special Issue entitled Current methods to study reactive oxygen species - pros and cons and biophysics of membrane proteins. Guest Editor: Christine Winterbourn. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Mgm101p is a novel component of the mitochondrial nucleoid that binds DNA and is required for the repair of oxidatively damaged mitochondrial DNA

    Meeusen, S.; Tieu, Q.; Wong, E.; Weiss, E.; Schieltz, D.; Yates, J.R.; Nunnari, J.

    1999-01-01

    Maintenance of mitochondrial DNA (mtDNA) during cell division is required for progeny to be respiratory competent. Maintenance involves the replication, repair, assembly, segregation, and partitioning of the mitochondrial nucleoid. MGM101 has been identified as a gene essential for mtDNA maintenance in S. cerevisiae, but its role is unknown. Using liquid chromatography coupled with tandem mass spectrometry, we identified Mgm101p as a component of highly enriched nucleoids, suggesting that it plays a nucleoid-specific role in maintenance. Subcellular fractionation, indirect immunofluorescence and GFP tagging show that Mgm101p is exclusively associated with the mitochondrial nucleoid structure in cells. Furthermore, DNA affinity chromatography of nucleoid extracts indicates that Mgm101p binds to DNA, suggesting that its nucleoid localization is in part due to this activity. Phenotypic analysis of cells containing a temperature sensitive mgm101 allele suggests that Mgm101p is not involved in mtDNA packaging, segregation, partitioning or required for ongoing mtDNA replication. We examined Mgm101p's role in mtDNA repair. As compared with wild-type cells, mgm101 cells were more sensitive to mtDNA damage induced by UV irradiation and were hypersensitive to mtDNA damage induced by gamma rays and H2O2 treatment. Thus, we propose that Mgm101p performs an essential function in the repair of oxidatively damaged mtDNA that is required for the maintenance of the mitochondrial genome. (author)

  9. Osseointegration improvement by plasma electrolytic oxidation of modified titanium alloys surfaces.

    Echeverry-Rendón, Mónica; Galvis, Oscar; Quintero Giraldo, David; Pavón, Juan; López-Lacomba, José Luis; Jiménez-Piqué, Emilio; Anglada, Marc; Robledo, Sara M; Castaño, Juan G; Echeverría, Félix

    2015-02-01

    Titanium (Ti) is a material frequently used in orthopedic applications, due to its good mechanical properties and high corrosion resistance. However, formation of a non-adherent fibrous tissue between material and bone drastically could affect the osseointegration process and, therefore, the mechanical stability of the implant. Modifications of topography and configuration of the tissue/material interface is one of the mechanisms to improve that process by manipulating parameters such as morphology and roughness. There are different techniques that can be used to modify the titanium surface; plasma electrolytic oxidation (PEO) is one of those alternatives, which consists of obtaining porous anodic coatings by controlling parameters such as voltage, current, anodizing solution and time of the reaction. From all of the above factors, and based on previous studies that demonstrated that bone cells sense substrates features to grow new tissue, in this work commercially pure Ti (c.p Ti) and Ti6Al4V alloy samples were modified at their surface by PEO in different anodizing solutions composed of H2SO4 and H3PO4 mixtures. Treated surfaces were characterized and used as platforms to grow osteoblasts; subsequently, cell behavior parameters like adhesion, proliferation and differentiation were also studied. Although the results showed no significant differences in proliferation, differentiation and cell biological activity, overall results showed an important influence of topography of the modified surfaces compared with polished untreated surfaces. Finally, this study offers an alternative protocol to modify surfaces of Ti and their alloys in a controlled and reproducible way in which biocompatibility of the material is not compromised and osseointegration would be improved.

  10. NAA-modified DNA oligonucleotides with zwitterionic backbones: stereoselective synthesis of A-T phosphoramidite building blocks.

    Schmidtgall, Boris; Höbartner, Claudia; Ducho, Christian

    2015-01-01

    Modifications of the nucleic acid backbone are essential for the development of oligonucleotide-derived bioactive agents. The NAA-modification represents a novel artificial internucleotide linkage which enables the site-specific introduction of positive charges into the otherwise polyanionic backbone of DNA oligonucleotides. Following initial studies with the introduction of the NAA-linkage at T-T sites, it is now envisioned to prepare NAA-modified oligonucleotides bearing the modification at X-T motifs (X = A, C, G). We have therefore developed the efficient and stereoselective synthesis of NAA-linked 'dimeric' A-T phosphoramidite building blocks for automated DNA synthesis. Both the (S)- and the (R)-configured NAA-motifs were constructed with high diastereoselectivities to furnish two different phosphoramidite reagents, which were employed for the solid phase-supported automated synthesis of two NAA-modified DNA oligonucleotides. This represents a significant step to further establish the NAA-linkage as a useful addition to the existing 'toolbox' of backbone modifications for the design of bioactive oligonucleotide analogues.

  11. JNK Phosphorylates SIRT6 to Stimulate DNA Double-Strand Break Repair in Response to Oxidative Stress by Recruiting PARP1 to DNA Breaks

    Michael Van Meter

    2016-09-01

    Full Text Available The accumulation of damage caused by oxidative stress has been linked to aging and to the etiology of numerous age-related diseases. The longevity gene, sirtuin 6 (SIRT6, promotes genome stability by facilitating DNA repair, especially under oxidative stress conditions. Here we uncover the mechanism by which SIRT6 is activated by oxidative stress to promote DNA double-strand break (DSB repair. We show that the stress-activated protein kinase, c-Jun N-terminal kinase (JNK, phosphorylates SIRT6 on serine 10 in response to oxidative stress. This post-translational modification facilitates the mobilization of SIRT6 to DNA damage sites and is required for efficient recruitment of poly (ADP-ribose polymerase 1 (PARP1 to DNA break sites and for efficient repair of DSBs. Our results demonstrate a post-translational mechanism regulating SIRT6, and they provide the link between oxidative stress signaling and DNA repair pathways that may be critical for hormetic response and longevity assurance.

  12. Detection of genetically modified organisms (GMOs) using isothermal amplification of target DNA sequences.

    Lee, David; La Mura, Maurizio; Allnutt, Theo R; Powell, Wayne

    2009-02-02

    The most common method of GMO detection is based upon the amplification of GMO-specific DNA amplicons using the polymerase chain reaction (PCR). Here we have applied the loop-mediated isothermal amplification (LAMP) method to amplify GMO-related DNA sequences, 'internal' commonly-used motifs for controlling transgene expression and event-specific (plant-transgene) junctions. We have tested the specificity and sensitivity of the technique for use in GMO studies. Results show that detection of 0.01% GMO in equivalent background DNA was possible and dilutions of template suggest that detection from single copies of the template may be possible using LAMP. This work shows that GMO detection can be carried out using LAMP for routine screening as well as for specific events detection. Moreover, the sensitivity and ability to amplify targets, even with a high background of DNA, here demonstrated, highlights the advantages of this isothermal amplification when applied for GMO detection.

  13. Electrochemical sensor for multiplex screening of genetically modified DNA: identification of biotech crops by logic-based biomolecular analysis.

    Liao, Wei-Ching; Chuang, Min-Chieh; Ho, Ja-An Annie

    2013-12-15

    Genetically modified (GM) technique, one of the modern biomolecular engineering technologies, has been deemed as profitable strategy to fight against global starvation. Yet rapid and reliable analytical method is deficient to evaluate the quality and potential risk of such resulting GM products. We herein present a biomolecular analytical system constructed with distinct biochemical activities to expedite the computational detection of genetically modified organisms (GMOs). The computational mechanism provides an alternative to the complex procedures commonly involved in the screening of GMOs. Given that the bioanalytical system is capable of processing promoter, coding and species genes, affirmative interpretations succeed to identify specified GM event in terms of both electrochemical and optical fashions. The biomolecular computational assay exhibits detection capability of genetically modified DNA below sub-nanomolar level and is found interference-free by abundant coexistence of non-GM DNA. This bioanalytical system, furthermore, sophisticates in array fashion operating multiplex screening against variable GM events. Such a biomolecular computational assay and biosensor holds great promise for rapid, cost-effective, and high-fidelity screening of GMO. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Replication stress and oxidative damage contribute to aberrant constitutive activation of DNA damage signalling in human gliomas

    Bartkova, J; Hamerlik, P; Stockhausen, Marie

    2010-01-01

    brain and grade II astrocytomas, despite the degree of DDR activation was higher in grade II tumors. Markers indicative of ongoing DNA replication stress (Chk1 activation, Rad17 phosphorylation, replication protein A foci and single-stranded DNA) were present in GBM cells under high- or low...... and indicate that replication stress, rather than oxidative stress, fuels the DNA damage signalling in early stages of astrocytoma development.......Malignant gliomas, the deadliest of brain neoplasms, show rampant genetic instability and resistance to genotoxic therapies, implicating potentially aberrant DNA damage response (DDR) in glioma pathogenesis and treatment failure. Here, we report on gross, aberrant constitutive activation of DNA...

  15. Acetone sensors based on TiO{sub 2} nanocrystals modified with tungsten oxide species

    Epifani, Mauro, E-mail: mauro.epifani@le.imm.cnr.it [Consiglio Nazionale delle Ricerche – Istituto per la Microelettronica e Microsistemi (CNR-IMM), via Monteroni c/o Campus Universitario, I-73100, Lecce (Italy); Comini, Elisabetta [SENSOR Lab, Department of Information Engineering, Brescia University and CNR-INO, via Valotti, 9, 25133 Brescia (Italy); Díaz, Raül [Electrochemical Processes Unit, IMDEA Energy Institute, Avda. Ramón de la Sagra, 3 28935 Móstoles (Spain); Genç, Aziz [Metallurgy and Materials Engineering Department, Faculty of Engineering, Bartin University, 74100, Bartin (Turkey); Andreu, Teresa [Catalonia Institute for Energy Research- (IREC), Jardíns de les Dones de Negre, 1, E-08930 Sant Adrià del Besos, Barcelona, CAT (Spain); Siciliano, Pietro [Consiglio Nazionale delle Ricerche – Istituto per la Microelettronica e Microsistemi (CNR-IMM), via Monteroni c/o Campus Universitario, I-73100, Lecce (Italy); Morante, Joan R. [Catalonia Institute for Energy Research- (IREC), Jardíns de les Dones de Negre, 1, E-08930 Sant Adrià del Besos, Barcelona, CAT (Spain); Departament d' Electrònica, Universitat de Barcelona, C./ Martí i Franquès 1, E-08028 Barcelona (Spain)

    2016-04-25

    TiO{sub 2} nanocrystals were prepared by sol–gel/solvothermal processing and modified by the addition of W precursor before the solvothermal step. The W: Ti nominal atomic ratio (R{sub W}) was fixed to 0.16 and 0.64. Surface modification of TiO{sub 2} occurred for R{sub W} = 0.16 while for R{sub W} = 0.64 nanocomposites with WO{sub 3} nanocrystals were obtained after heat-treatment at 500 °C. Pure TiO{sub 2} proved to be very poorly performing in acetone sensing in all the operating conditions. Instead, the addition of both W concentrations largely enhanced the sensor response. It ranged over two orders of magnitude of conductance variation for all the tested concentrations at as low as 200 °C operating temperature. The results showed that it is possible to enhance the performance of an otherwise almost inactive oxide like TiO{sub 2} by proper combination with another more active oxide like WO{sub 3}. - Highlights: • Sensing architecture are synthesized, combining WO{sub 3} and of TiO{sub 2} nanocrystals. • Surface layers of W oxides or heterojunctions of TiO{sub 2} and WO{sub 3} are obtained. • Simple TiO{sub 2} surface modification by W oxides boosts the TiO{sub 2} acetone response. • High responses even at 200 °C show catalytic effect of WO{sub 3} addition.

  16. Immobilization/hybridization of amino-modified DNA on plasma-polymerized allyl chloride

    Zhang Zhihong; Feng Chuanliang

    2007-01-01

    The present work describes the fabrication and characterization of chloride-derivatized polymer coatings prepared by continuous wave (cw) plasma polymerization as adhesion layers in DNA immobilization/hybridization. The stability of plasma-polymerized allyl chloride (ppAC) in H 2 O was characterized by variation of the thickness of polymer films and its wettability was examined by water contact angle technique. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to study polymer matrix properties and oligonucleotide/DNA binding interaction. With the same carrier gas rate and process pressure, plasma polymers deposited at different input powers show various comparable immobilization properties; nevertheless, low input power plasma-polymerized films gives a lower sensitivity toward DNA binding than that from high input power plasma-deposited films. The following DNA immobilization on chloride-functionalized surfaces was found dependence on the macromolecular architecture of the plasma films. The hybridization between probe DNA and total mismatch target DNA shows no non-specific adsorption between target and ppAC

  17. Critical points of DNA quantification by real-time PCR – effects of DNA extraction method and sample matrix on quantification of genetically modified organisms

    Žel Jana

    2006-08-01

    Full Text Available Abstract Background Real-time PCR is the technique of choice for nucleic acid quantification. In the field of detection of genetically modified organisms (GMOs quantification of biotech products may be required to fulfil legislative requirements. However, successful quantification depends crucially on the quality of the sample DNA analyzed. Methods for GMO detection are generally validated on certified reference materials that are in the form of powdered grain material, while detection in routine laboratories must be performed on a wide variety of sample matrixes. Due to food processing, the DNA in sample matrixes can be present in low amounts and also degraded. In addition, molecules of plant origin or from other sources that affect PCR amplification of samples will influence the reliability of the quantification. Further, the wide variety of sample matrixes presents a challenge for detection laboratories. The extraction method must ensure high yield and quality of the DNA obtained and must be carefully selected, since even components of DNA extraction solutions can influence PCR reactions. GMO quantification is based on a standard curve, therefore similarity of PCR efficiency for the sample and standard reference material is a prerequisite for exact quantification. Little information on the performance of real-time PCR on samples of different matrixes is available. Results Five commonly used DNA extraction techniques were compared and their suitability for quantitative analysis was assessed. The effect of sample matrix on nucleic acid quantification was assessed by comparing 4 maize and 4 soybean matrixes. In addition 205 maize and soybean samples from routine analysis were analyzed for PCR efficiency to assess variability of PCR performance within each sample matrix. Together with the amount of DNA needed for reliable quantification, PCR efficiency is the crucial parameter determining the reliability of quantitative results, therefore it was

  18. Critical points of DNA quantification by real-time PCR--effects of DNA extraction method and sample matrix on quantification of genetically modified organisms.

    Cankar, Katarina; Stebih, Dejan; Dreo, Tanja; Zel, Jana; Gruden, Kristina

    2006-08-14

    Real-time PCR is the technique of choice for nucleic acid quantification. In the field of detection of genetically modified organisms (GMOs) quantification of biotech products may be required to fulfil legislative requirements. However, successful quantification depends crucially on the quality of the sample DNA analyzed. Methods for GMO detection are generally validated on certified reference materials that are in the form of powdered grain material, while detection in routine laboratories must be performed on a wide variety of sample matrixes. Due to food processing, the DNA in sample matrixes can be present in low amounts and also degraded. In addition, molecules of plant origin or from other sources that affect PCR amplification of samples will influence the reliability of the quantification. Further, the wide variety of sample matrixes presents a challenge for detection laboratories. The extraction method must ensure high yield and quality of the DNA obtained and must be carefully selected, since even components of DNA extraction solutions can influence PCR reactions. GMO quantification is based on a standard curve, therefore similarity of PCR efficiency for the sample and standard reference material is a prerequisite for exact quantification. Little information on the performance of real-time PCR on samples of different matrixes is available. Five commonly used DNA extraction techniques were compared and their suitability for quantitative analysis was assessed. The effect of sample matrix on nucleic acid quantification was assessed by comparing 4 maize and 4 soybean matrixes. In addition 205 maize and soybean samples from routine analysis were analyzed for PCR efficiency to assess variability of PCR performance within each sample matrix. Together with the amount of DNA needed for reliable quantification, PCR efficiency is the crucial parameter determining the reliability of quantitative results, therefore it was chosen as the primary criterion by which to

  19. Critical points of DNA quantification by real-time PCR – effects of DNA extraction method and sample matrix on quantification of genetically modified organisms

    Cankar, Katarina; Štebih, Dejan; Dreo, Tanja; Žel, Jana; Gruden, Kristina

    2006-01-01

    Background Real-time PCR is the technique of choice for nucleic acid quantification. In the field of detection of genetically modified organisms (GMOs) quantification of biotech products may be required to fulfil legislative requirements. However, successful quantification depends crucially on the quality of the sample DNA analyzed. Methods for GMO detection are generally validated on certified reference materials that are in the form of powdered grain material, while detection in routine laboratories must be performed on a wide variety of sample matrixes. Due to food processing, the DNA in sample matrixes can be present in low amounts and also degraded. In addition, molecules of plant origin or from other sources that affect PCR amplification of samples will influence the reliability of the quantification. Further, the wide variety of sample matrixes presents a challenge for detection laboratories. The extraction method must ensure high yield and quality of the DNA obtained and must be carefully selected, since even components of DNA extraction solutions can influence PCR reactions. GMO quantification is based on a standard curve, therefore similarity of PCR efficiency for the sample and standard reference material is a prerequisite for exact quantification. Little information on the performance of real-time PCR on samples of different matrixes is available. Results Five commonly used DNA extraction techniques were compared and their suitability for quantitative analysis was assessed. The effect of sample matrix on nucleic acid quantification was assessed by comparing 4 maize and 4 soybean matrixes. In addition 205 maize and soybean samples from routine analysis were analyzed for PCR efficiency to assess variability of PCR performance within each sample matrix. Together with the amount of DNA needed for reliable quantification, PCR efficiency is the crucial parameter determining the reliability of quantitative results, therefore it was chosen as the primary

  20. [Occupational hazards, DNA damage, and oxidative stress on exposure to waste anesthetic gases].

    Lucio, Lorena M C; Braz, Mariana G; do Nascimento Junior, Paulo; Braz, José Reinaldo C; Braz, Leandro G

    The waste anesthetic gases (WAGs) present in the ambient air of operating rooms (OR), are associated with various occupational hazards. This paper intends to discuss occupational exposure to WAGs and its impact on exposed professionals, with emphasis on genetic damage and oxidative stress. Despite the emergence of safer inhaled anesthetics, occupational exposure to WAGs remains a current concern. Factors related to anesthetic techniques and anesthesia workstations, in addition to the absence of a scavenging system in the OR, contribute to anesthetic pollution. In order to minimize the health risks of exposed professionals, several countries have recommended legislation with maximum exposure limits. However, developing countries still require measurement of WAGs and regulation for occupational exposure to WAGs. WAGs are capable of inducing damage to the genetic material, such as DNA damage assessed using the comet assay and increased frequency of micronucleus in professionals with long-term exposure. Oxidative stress is also associated with WAGs exposure, as it induces lipid peroxidation, oxidative damage in DNA, and impairment of the antioxidant defense system in exposed professionals. The occupational hazards related to WAGs including genotoxicity, mutagenicity and oxidative stress, stand as a public health issue and must be acknowledged by exposed personnel and responsible authorities, especially in developing countries. Thus, it is urgent to stablish maximum safe limits of concentration of WAGs in ORs and educational practices and protocols for exposed professionals. Copyright © 2017 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

  1. Application of three-dimensional reduced graphene oxide-gold composite modified electrode for direct electrochemistry and electrocatalysis of myoglobin

    Shi, Fan; Xi, Jingwen; Hou, Fei; Han, Lin; Li, Guangjiu; Gong, Shixing; Chen, Chanxing; Sun, Wei

    2016-01-01

    In this paper a three-dimensional (3D) reduced graphene oxide (RGO) and gold (Au) composite was synthesized by electrodeposition and used for the electrode modification with carbon ionic liquid electrode (CILE) as the substrate electrode. Myoglobin (Mb) was further immobilized on the surface of 3D RGO–Au/CILE to obtain an electrochemical sensing platform. Direct electrochemistry of Mb on the modified electrode was investigated with a pair of well-defined redox waves appeared on cyclic voltammogram, indicating the realization of direct electron transfer of Mb with the modified electrode. The results can be ascribed to the presence of highly conductive 3D RGO–Au composite on the electrode surface that accelerate the electron transfer rate between the electroactive center of Mb and the electrode. The Mb modified electrode showed excellent electrocatalytic activity to the reduction of trichloroacetic acid in the concentration range from 0.2 to 36.0 mmol/L with the detection limit of 0.06 mmol/L (3σ). - Graphical abstract: Direct electrochemistry of myoglobin was realized on a three-dimensional reduced graphene oxide and gold nanocomposite modified carbon ionic liquid electrode. - Highlights: • A three-dimensional reduced graphene oxide and gold composite was synthesized by electrodeposition. • Myoglobin was immobilized on the modified electrode to obtain an electrochemical sensor. • Direct electrochemistry of myoglobin was realized on the modified electrode. • The myoglobin modified electrode showed excellent electrocatalytic reduction to trichloroacetic acid.

  2. Lack of association of colonic epithelium telomere length and oxidative DNA damage in Type 2 diabetes under good metabolic control

    Kennedy Hugh

    2008-10-01

    Full Text Available Abstract Background Telomeres are DNA repeat sequences necessary for DNA replication which shorten at cell division at a rate directly related to levels of oxidative stress. Critical telomere shortening predisposes to cell senescence and to epithelial malignancies. Type 2 diabetes is characterised by increased oxidative DNA damage, telomere attrition, and an increased risk of colonic malignancy. We hypothesised that the colonic mucosa in Type 2 diabetes would be characterised by increased DNA damage and telomere shortening. Methods We examined telomere length (by flow fluorescent in situ hybridization and oxidative DNA damage (flow cytometry of 8 – oxoguanosine in the colonic mucosal cells of subjects with type 2 diabetes (n = 10; mean age 62.2 years, mean HbA1c 6.9% and 22 matched control subjects. No colonic pathology was apparent in these subjects at routine gastrointestinal investigations. Results Mean colonic epithelial telomere length in the diabetes group was not significantly different from controls (10.6 [3.6] vs. 12.1 [3.4] Molecular Equivalent of Soluble Fluorochrome Units [MESF]; P = 0.5. Levels of oxidative DNA damage were similar in both T2DM and control groups (2.6 [0.6] vs. 2.5 [0.6] Mean Fluorescent Intensity [MFI]; P = 0.7. There was no significant relationship between oxidative DNA damage and telomere length in either group (both p > 0.1. Conclusion Colonic epithelium in Type 2 diabetes does not differ significantly from control colonic epithelium in oxidative DNA damage or telomere length. There is no evidence in this study for increased oxidative DNA damage or significant telomere attrition in colonic mucosa as a carcinogenic mechanism.

  3. Oxidative DNA damage in vitamin C-supplemented guinea pigs after intratracheal instillation of diesel exhaust particles

    Moller, P.; Daneshvar, B.; Loft, S.

    2003-01-01

    . The concentrations of ascorbate in liver, lung, and plasma were unaltered by the DEP exposure. The results indicate that in guinea pigs DEP causes oxidative DNA damage rather than bulky DNA adducts in the lung. Guinea pigs, which are similar to humans with respect to vitamin C metabolism, may serve as a new model...... for the study of oxidative damage induced by particulate matter. (C) 2003 Elsevier Science (USA). All rights reserved....

  4. Methanol oxidation at carbon paste electrodes modified with (Pt–Ru)/carbon aerogels nanocomposites

    Fort, Carmen I., E-mail: iladiu@chem.ubbcluj.ro [Laboratory of Electrochemical Research and Nonconventional Materials, Babes-Bolyai University, Arany Janos 11, RO-400028, Cluj-Napoca (Romania); Cotet, Liviu C. [Laboratory of Electrochemical Research and Nonconventional Materials, Babes-Bolyai University, Arany Janos 11, RO-400028, Cluj-Napoca (Romania); Vasiliu, Florin [The National Institute of Materials Physics, Atomistilor str. 105 bis, PO Box MG. 7, Magurele, RO 077125, Bucharest (Romania); Marginean, Petre [National Institute for Research and Development of Isotopic and Molecular Technologies, RO 400293, Cluj-Napoca (Romania); Danciu, Virginia; Popescu, Ionel C. [Laboratory of Electrochemical Research and Nonconventional Materials, Babes-Bolyai University, Arany Janos 11, RO-400028, Cluj-Napoca (Romania)

    2016-04-01

    Mesoporous carbon aerogels (CAs) impregnated with (Pt–Ru) nanoparticles were prepared, incorporated into carbon paste electrodes (CPEs) and investigated as electrocatalysts for CH{sub 3}OH electro-oxidation. The sol–gel method, followed by supercritical drying with liquid CO{sub 2} and thermal pyrolysis in an inert atmosphere, was used to obtain high mesoporous CAs. (Pt–Ru)/CAs nanocomposites with various (Pt–Ru) loading were prepared by using Ru(AcAc){sub 3} and H{sub 2}PtCl{sub 6} as metal precursors and the impregnation method. The morpho-structural peculiarities of the so prepared (Pt–Ru)/CAs electrocatalysts were examined by using elemental analysis, N{sub 2} adsorption-desorption isotherms, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX) and selected area electron diffraction (SAED). Cyclic voltammetry measurements, carried out at (Pt–Ru)/CA-CPEs incorporating nanocomposites with various Pt–Ru loading and different specific surface areas, showed that CA with the highest specific surface area (843 m{sup 2}/g) and impregnated with 6% (w/w) (Pt–Ru) nanoparticles exhibit the best CH{sub 3}OH electro-oxidation efficiency. The Michaelis–Menten formalism was used to describe the dependence of the oxidation peak current on the CH{sub 3}OH concentration, allowing the estimation of the modified electrodes sensitivities. Thus, for (Pt–Ru, 10%)/CA{sub 535}-CPE was observed the highest sensitivity (12.5 ± 0.8 mA/M) and, at the same time, the highest maximum current density ever reported (153.1 mA/cm{sup 2} for 2 M CH{sub 3}OH and an applied potential of 600 mV vs. SHE). - Highlights: • (Pt–Ru) nanoparticles were deposited on high mesoporous carbon aerogels (CAs). • (Pt–Ru)/CAs were characterized by TEM, EDX, SAED and N{sub 2} adsorption-desorption. • Carbon paste electrodes modified with (Pt–Ru)/CA were used for CH{sub 3}OH oxidation. • (Pt–Ru, 10

  5. Magnetic Hyperthermia and Oxidative Damage to DNA of Human Hepatocarcinoma Cells

    Filippo Cellai

    2017-04-01

    Full Text Available Nanotechnology is addressing major urgent needs for cancer treatment. We conducted a study to compare the frequency of 3-(2-deoxy-β-d-erythro-pentafuranosylpyrimido[1,2-α]purin-10(3H-one deoxyguanosine (M1dG and 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG adducts, biomarkers of oxidative stress and/or lipid peroxidation, on human hepatocarcinoma HepG2 cells exposed to increasing levels of Fe3O4-nanoparticles (NPs versus untreated cells at different lengths of incubations, and in the presence of increasing exposures to an alternating magnetic field (AMF of 186 kHz using 32P-postlabeling. The levels of oxidative damage tended to increase significantly after ≥24 h of incubations compared to controls. The oxidative DNA damage tended to reach a steady-state after treatment with 60 μg/mL of Fe3O4-NPs. Significant dose–response relationships were observed. A greater adduct production was observed after magnetic hyperthermia, with the highest amounts of oxidative lesions after 40 min exposure to AMF. The effects of magnetic hyperthermia were significantly increased with exposure and incubation times. Most important, the levels of oxidative lesions in AMF exposed NP treated cells were up to 20-fold greater relative to those observed in nonexposed NP treated cells. Generation of oxidative lesions may be a mechanism by which magnetic hyperthermia induces cancer cell death.

  6. Magnetic Hyperthermia and Oxidative Damage to DNA of Human Hepatocarcinoma Cells.

    Cellai, Filippo; Munnia, Armelle; Viti, Jessica; Doumett, Saer; Ravagli, Costanza; Ceni, Elisabetta; Mello, Tommaso; Polvani, Simone; Giese, Roger W; Baldi, Giovanni; Galli, Andrea; Peluso, Marco E M

    2017-04-29

    Nanotechnology is addressing major urgent needs for cancer treatment. We conducted a study to compare the frequency of 3-(2-deoxy-β-d-erythro-pentafuranosyl)pyrimido[1,2-α]purin-10(3 H )-one deoxyguanosine (M₁dG) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) adducts, biomarkers of oxidative stress and/or lipid peroxidation, on human hepatocarcinoma HepG2 cells exposed to increasing levels of Fe₃O₄-nanoparticles (NPs) versus untreated cells at different lengths of incubations, and in the presence of increasing exposures to an alternating magnetic field (AMF) of 186 kHz using 32 P-postlabeling. The levels of oxidative damage tended to increase significantly after ≥24 h of incubations compared to controls. The oxidative DNA damage tended to reach a steady-state after treatment with 60 μg/mL of Fe₃O₄-NPs. Significant dose-response relationships were observed. A greater adduct production was observed after magnetic hyperthermia, with the highest amounts of oxidative lesions after 40 min exposure to AMF. The effects of magnetic hyperthermia were significantly increased with exposure and incubation times. Most important, the levels of oxidative lesions in AMF exposed NP treated cells were up to 20-fold greater relative to those observed in nonexposed NP treated cells. Generation of oxidative lesions may be a mechanism by which magnetic hyperthermia induces cancer cell death.

  7. Assessment of DNA damage and oxidative stress induced by radiation in Eisenia fetida

    Ryu, Tae Ho; Kim, Jin Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Nili, Mohammad [Dawnesh Radiation Research Institute, Barcelona (Spain)

    2012-04-15

    Exposure of eukaryotic cells to ionizing radiation results in the immediate formation of free radicals and the occurrence of oxidative cell damage. Recently International Commission on Radiological Protection (ICRP) requires the effect data of ionizing radiation on non-human biota for the radiological protection of the environment. Based on their radioecological properties and their important role in the soil ecosystem, earthworms have been identified by the ICRP as one of the reference animals and plants (RAPs) to be used in environmental radiation protection. The investigation shows that oxidative stress is closely related to the exposed dose of radiation in the environment. To evaluate oxidative stress by ionizing radiation in the earthworm, we performed several experiments. The comet assay is known as a measurement which is one of the best techniques in assessing the DNA damage by oxidative stress. The SOD is a key enzyme in protecting cells against oxidative stress. An increase in the level of antioxidant enzyme such as SOD indicated that the exposure to radiation caused stress responses. Glutathione oxidation is considered as a maker for detection of reactive oxygen species (ROS). The GSSG levels increased progressively with increased exposure dose of ionizing radiation, which suggested a dose-dependent ROS generation.

  8. Direct extraction of genomic DNA from maize with aqueous ionic liquid buffer systems for applications in genetically modified organisms analysis.

    Gonzalez García, Eric; Ressmann, Anna K; Gaertner, Peter; Zirbs, Ronald; Mach, Robert L; Krska, Rudolf; Bica, Katharina; Brunner, Kurt

    2014-12-01

    To date, the extraction of genomic DNA is considered a bottleneck in the process of genetically modified organisms (GMOs) detection. Conventional DNA isolation methods are associated with long extraction times and multiple pipetting and centrifugation steps, which makes the entire procedure not only tedious and complicated but also prone to sample cross-contamination. In recent times, ionic liquids have emerged as innovative solvents for biomass processing, due to their outstanding properties for dissolution of biomass and biopolymers. In this study, a novel, easily applicable, and time-efficient method for the direct extraction of genomic DNA from biomass based on aqueous-ionic liquid solutions was developed. The straightforward protocol relies on extraction of maize in a 10 % solution of ionic liquids in aqueous phosphate buffer for 5 min at room temperature, followed by a denaturation step at 95 °C for 10 min and a simple filtration to remove residual biopolymers. A set of 22 ionic liquids was tested in a buffer system and 1-ethyl-3-methylimidazolium dimethylphosphate, as well as the environmentally benign choline formate, were identified as ideal candidates. With this strategy, the quality of the genomic DNA extracted was significantly improved and the extraction protocol was notably simplified compared with a well-established method.

  9. Modifying action of DNA synthesis precursors on Aspergillus nidulans conidium irradiated by ultraviolet and X-rays

    Muronets, E.M.; Kameneva, S.V.

    1975-01-01

    Modification of inactivation action of radiation on conidia Aspergillus nidulans, UVS + and UVS strains, by desoxynucleosides, purine and pyrimidine bases is shown. The modification manifested in increased conidia survival is revealed when the precursor of DNA synthesis is added to the suspension before exposure to ultraviolet or X-rays. In the case of postradiation application of the substance no modification is observed. The modifying effect of different precursors becomes equally apparent with equimolar solutions and increases at higher concentration of the latter. An increase in thymidine endogenic pool in the exposed conidia does not affect their survival. When conidia are exposed to ultraviolet rays through a thymidine filter the survival rate increases to the same extent as in the case when they are exposed to irradiation in thymidine solution. The authors suggest that modification of the inactivating radiation action by DNA precursors at exposure of conidia Aspergillus nidulans is caused by the radioprotective effect of precursors not related to reparation [ru

  10. Efficient assessment of modified nucleoside stability under conditions of automated oligonucleotide synthesis: characterization of the oxidation and oxidative desulfurization of 2-thiouridine.

    Sochacka, E

    2001-01-01

    In order to efficiently assess the chemical stability of modified nucleosides to the reagents and conditions of automated oligonucleotide synthesis, we designed, developed and tested a scheme in which the modified nucleoside, directly attached to a solid support, is exposed to the cyclic chemistry of the instrument. Stability of 2-thiouridine against different oxidizers was investigated. Tertbutyl hydroperoxide (1 M) in anhydrous acetonitrile was a more effective oxidizer for the incorporation of 2-thiouridine into oligonucleotide chains than the same oxidizer in methylene chloride. Carbon tetrachloride/water in the presence of a basic catalyst was superior in maintaining the thiocarbonyl function, but its utility for RNA synthesis has yet to be fully tested, whereas 2-phenylsulfonyloxaziridine was a very efficient reagent for oxidative desulfurization of 2-thiouridine.

  11. Study of NiO cathode modified by rare earth oxide additive for MCFC by electrochemical impedance spectroscopy

    Huang Bo; Chen Gang; Li Fei; Yu Qingchun; Hu Keao

    2004-01-01

    The preparation and subsequent oxidation of nickel cathodes modified by impregnation with rare earth oxide were evaluated by surface and bulk analysis. The electrochemical behaviors of rare earth oxide impregnated nickel oxide cathodes were also evaluated in a molten 62 mol% Li 2 CO 3 +38 mol% K 2 CO 3 eutectic at 650 deg. C by electrochemical impedance spectroscopy (EIS) as a function of rare earth oxide content and immersion time. The rare earth oxide-impregnated nickel cathodes show almost the similar porosity, pore size, and morphology to the reference nickel cathode. The stability tests of rare earth oxide-impregnated nickel oxide cathodes show that the rare earth oxide additive can dramatically reduce the solubility of nickel oxide in a eutectic carbonate mixture under the standard cathode gas condition. The impedance response of all cathode materials at different immersion time is characterized by the presence of depressed semicircles in the high frequency range changing over into the lines with the angles of which observed with the real axis differing 45 deg. or 90 deg. in the low frequency range. The experimental Nyquist plots can be well analyzed theoretically with a modified model based on the well-known Randles-Ershler equivalent circuit model. In the new model, the double layer capacity (C d ) is replaced by the parallel combination of C d and b/ω; therefore, this circuit is modified to be the parallel combination of (C d ), b/ω, and the charge transfer resistance (R ct ) based on the Randles-Ershler equivalent circuit, to take into consideration both the non-uniformity of electric field at the electrode/electrolyte interface owing to the roughness of electrode surface, and the variety of relaxation times with adsorbed species on the electrode surface. The impedance spectra for all cathode materials show important variations during the 200 h of immersion. The incorporation of lithium in its structure and the low dissolution of nickel oxide and rare

  12. Separating nano graphene oxide from the residual strong-acid filtrate of the modified Hummers method with alkaline solution

    Hu, Xuebing, E-mail: xuebinghu2010@gmail.com [Key Laboratory of Inorganic Membrane, Jingdezhen Ceramic Institute, Jingdezhen 333001 (China); Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai 201800 (China); Yu, Yun, E-mail: yunyush@mail.sic.ac.cn [Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai 201800 (China); Wang, Yongqing; Zhou, Jianer [Key Laboratory of Inorganic Membrane, Jingdezhen Ceramic Institute, Jingdezhen 333001 (China); Song, Lixin [Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai 201800 (China)

    2015-02-28

    Graphical abstract: By adding an alkaline (NaOH or KOH) solution, the unprecipitated nano graphene oxide undergoes fast aggregation from the residual strong-acid filtrate of the modified Hummers method and forms the stable floccules when the pH value of the filtrate is about 1.7. The acid–base interaction with the surface functional groups of the carbon layers plays a role in the aggregation of the unprecipitated nano graphene oxide. - Highlights: • The novel and high-efficient method for separating graphene oxide was showed. • Graphene oxide undergoes aggregation and forms the floccules when pH value is ∼1.7. • The acid–base interaction plays a role in the aggregation of graphene oxide. - Abstract: In the modified Hummers method for preparing graphene oxide, the yellow slurry can be obtained. After filtering through a quantitative filter paper, the strong-acid filtrate containing the unprecipitated nano graphene oxide was gained. The corresponding filtrate was added gradually with an alkaline (NaOH or KOH) solution at room temperature. The unprecipitated nano graphene oxide could undergo fast aggregation when the pH value of the filtrate was about 1.7 and formed the stable floccules. X-ray diffraction analysis shows the dominant peak of the floccules is about 11°, which accords to the peak of graphene oxide. Spectra of X-ray photoelectron spectroscopy confirm the presence in the floccules of an abundance of oxygen functional groups and the purified graphene oxide floccules can be obtained. Atomic force microscopy measurement shows the graphene oxide floccules consists of sheet-like objects, mostly containing only a few layers (about 5 layers). Zeta potential analysis demonstrates the surface charge of the graphene oxide is pH-sensitive and its isoelectric point is ∼1.7. The flocculation mechanism of graphene oxide ascribes to the acid–base interaction with the surface functional groups of the carbon layers.

  13. Efficient inverted bulk-heterojunction polymer solar cells with self-assembled monolayer modified zinc oxide.

    Kim, Wook Hyun; Lyu, Hong-Kun; Han, Yoon Soo; Woo, Sungho

    2013-10-01

    The performance of poly(3-hexylthiophen) (P3HT) and [6, 6]phenyl C61 butyric acid methyl ester ([60]PCBM)-based inverted bulk-heterojunction (BHJ) polymer solar cells (PSCs) is enhanced by the modification of zinc oxide (ZnO)/BHJ interface with carboxylic-acid-functionalized self-assembled monolayers (SAMs). Under simulated solar illumination of AM 1.5 (100 mW/cm2), the inverted devices fabricated with SAM-modified ZnO achieved an enhanced power conversion efficiency (PCE) of 3.34% due to the increased fill factor and photocurrent density as compared to unmodified cells with PCE of 2.60%. This result provides an efficient method for interface engineering in inverted BHJ PSCs.

  14. Significant electrical control of amorphous oxide thin film transistors by an ultrathin Ti surface polarity modifier

    Cho, Byungsu [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Samsung Display Co. Ltd., Tangjeong, Chungcheongnam-Do 336-741 (Korea, Republic of); Choi, Yonghyuk; Shin, Seokyoon [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Jeon, Heeyoung [Department of Nano-scale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Seo, Hyungtak, E-mail: hseo@ajou.ac.kr [Department of Materials Science and Engineering and Energy Systems Research, Ajou University, Suwon 443-739 (Korea, Republic of); Jeon, Hyeongtag, E-mail: hjeon@hanyang.ac.kr [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Department of Nano-scale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2014-01-27

    We demonstrate an enhanced electrical stability through a Ti oxide (TiO{sub x}) layer on the amorphous InGaZnO (a-IGZO) back-channel; this layer acts as a surface polarity modifier. Ultrathin Ti deposited on the a-IGZO existed as a TiO{sub x} thin film, resulting in oxygen cross-binding with a-IGZO surface. The electrical properties of a-IGZO thin film transistors (TFTs) with TiO{sub x} depend on the surface polarity change and electronic band structure evolution. This result indicates that TiO{sub x} on the back-channel serves as not only a passivation layer protecting the channel from ambient molecules or process variables but also a control layer of TFT device parameters.

  15. Composite anion-exchangers modified with nanoparticles of hydrated oxides of multivalent metals

    Maltseva, T. V.; Kolomiets, E. O.; Dzyazko, Yu. S.; Scherbakov, S.

    2018-02-01

    Organic-inorganic composite ion-exchangers based on anion exchange resins have been obtained. Particles of one-component and two-component modifier were embedded using the approach, which allows us to realize purposeful control of a size of the embedded particles. The approach is based on Ostwald-Freundlich equation, which was adapted to deposition in ion exchange matrix. The equation was obtained experimentally. Hydrated oxides of zirconium and iron were applied to modification, concentration of the reagents were varied. The embedded particles accelerate sorption, the rate of which is fitted by the model equation of chemical reactions of pseudo-second order. When sorption of arsenate ions from very diluted solution (50 µg dm-3) occurs, the composites show higher distribution coefficients comparing with the pristine resin.

  16. Reactive removal of 2-chloroethyl ethyl sulfide vapors under visible light irradiation by cerium oxide modified highly porous zirconium (hydr) oxide

    Mitchell, Joshua K.; Arcibar-Orozco, Javier A.; Bandosz, Teresa J., E-mail: tbandosz@ccny.cuny.edu

    2016-12-30

    Highlights: • Microporous zirconium-cerium (hydr) oxides were synthetized. • Ce presence narrowed the band gap of the materials. • The samples showed a high efficiency for removal of CEES vapors. • 1,2-Bis (ethyl thio) ethane and ethyl vinyl sulfide were the main reaction products. • 5% (Ce/Zr mol) addition of cerium oxide results in the best performing material. - Abstract: Highly porous cerium oxide modified Zr(OH){sub 4} samples were synthesized using a simple one stage urea precipitation method. The amorphicity level of zirconium hydroxide did not change upon addition of cerium oxide particles. A unique aspect of the cerium oxide-modified materials is the presence of both the oxide (CeO{sub 2}) and hydroxide (Zr(OH){sub 4}) phases resulting in a unique microporous structure of the final material. Extensive characterization using various chemical and physical methods revealed significant differences in the surface features. All synthesized materials were microporous and small additions of cerium oxide affected the surface chemistry. These samples were found as effective catalysts for a decontamination of mustard gas surrogate, 2-chloroethyl ethyl sulfide (CEES). Cerium oxide addition significantly decreased the band gap of zirconium hydroxide. Ethyl vinyl sulfide and 1,2-bis (Ethyl thio) ethane were identified as surface reaction products.

  17. Electrocatalytic Reduction-oxidation of Chlorinated Phenols using a Nanostructured Pd-Fe Modified Graphene Catalyst

    Shi, Qin; Wang, Hui; Liu, Shaolei; Pang, Lei; Bian, Zhaoyong

    2015-01-01

    A Pd-Fe modified graphene (Pd-Fe/G) catalyst was prepared by the Hummers oxidation method and bimetallic co-deposition method. The catalyst was then characterized by various characterization techniques and its electrochemical property toward the electrocatalytic reduction-oxidation of chlorinated phenols was investigated by using cyclic voltammetry and differential pulse voltammetry. The results of the characterization show that the Pd-Fe/G catalyst in which the weight proportion of Pd and Fe is 1:1 has an optimal surface performance. The diameter of the Pd-Fe particles is approximately 5.2 ± 0.3 nm, with a uniform distribution on the supporting graphene. This is smaller than the Pd particles of a Pd-modified graphene (Pd/G) catalyst. The Pd-Fe/G catalyst shows a higher electrocatalytic activity than the Pd/G catalyst for reductive dechlorination when feeding with hydrogen gas. The reductive peak potentials of −0.188 V, −0.836 V and −0.956 V in the DPV curves are attributed to the dechlorination of ortho-Cl, meta-Cl, and para-Cl in 2-chlorophenol, 3-chlorophenol and 4-chlorophenol, respectively. In accordance with an analysis of the frontier orbital theory, the order of ease of dechlorination with Pd-Fe/G catalyst is 2-chlorophenol > 3-chlorophenol > 4-chlorophenol. The Pd-Fe/G catalyst has a greater activity than the Pd/G catalyst in accelerating the two-electron reduction of O_2 to H_2O_2, which is attributed to the higher current of the reduction peak at approximately −0.40 V when feeding with oxygen gas. Therefore, the Pd-Fe/G catalyst exhibits a higher electrocatalytic activity than the Pd/G catalyst for the reductive dechlorination and acceleration of the two-electron reduction of O_2 to H_2O_2.

  18. Investigation of As(V) removal from acid mine drainage by iron (hydr) oxide modified zeolite.

    Nekhunguni, Pfano Mathews; Tavengwa, Nikita Tawanda; Tutu, Hlanganani

    2017-07-15

    In this work, the synthesis of iron (hydr) oxide modified zeolite was achieved through precipitation of iron on the zeolite. The structure and surface morphology of iron (hydr) oxide modified zeolite (IHOMZ) was studied by scanning electron microscopy (SEM), coupled with an energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared (FT-IR) spectra. The efficiency of IHOMZ was then investigated through batch technique for the extraction of As(V) from mine waste water. The optimum parameters for maximum As(V) adsorption were: an initial As(V) concentration (10 mg L -1 ), adsorbent dosage (3.0 g), contact time (90 min) and temperature (53 °C). The initial pH of the solution had no compelling effect on As(V) adsorption by IHOMZ. However, adsorption capacity was significantly affected by the solution temperature with 53 °C registering the maximum removal efficiency. The thermodynamic parameters: Entropy (ΔS° = 0.00815 kJ (K mol) -1 ), variation of the Gibbs free energy (ΔG°) and enthalpy (ΔH° = 9.392 kJ mol -1 ) of As(V) adsorption onto IHOMZ system signified a non-spontaneous and endothermic process. It was noted that Freundlich isotherm model exhibited a better fit to the equilibrium experimental data, implying that the adsorption process occurred on a heterogeneous surface. The kinetic data from As(V) adsorption experiments was depicted by the pseudo-second-order kinetic model (R 2  > 0.999), suggesting a chemisorption adsorption process. The experimental batch equilibrium results indicated that IHOMZ could be used as an effective sorbent for As(V) ion extraction from acid mine drainage. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Low intensity microwave radiation induced oxidative stress, inflammatory response and DNA damage in rat brain.

    Megha, Kanu; Deshmukh, Pravin Suryakantrao; Banerjee, Basu Dev; Tripathi, Ashok Kumar; Ahmed, Rafat; Abegaonkar, Mahesh Pandurang

    2015-12-01

    Over the past decade people have been constantly exposed to microwave radiation mainly from wireless communication devices used in day to day life. Therefore, the concerns over potential adverse effects of microwave radiation on human health are increasing. Until now no study has been proposed to investigate the underlying causes of genotoxic effects induced by low intensity microwave exposure. Thus, the present study was undertaken to determine the influence of low intensity microwave radiation on oxidative stress, inflammatory response and DNA damage in rat brain. The study was carried out on 24 male Fischer 344 rats, randomly divided into four groups (n=6 in each group): group I consisted of sham exposed (control) rats, group II-IV consisted of rats exposed to microwave radiation at frequencies 900, 1800 and 2450 MHz, specific absorption rates (SARs) 0.59, 0.58 and 0.66 mW/kg, respectively in gigahertz transverse electromagnetic (GTEM) cell for 60 days (2h/day, 5 days/week). Rats were sacrificed and decapitated to isolate hippocampus at the end of the exposure duration. Low intensity microwave exposure resulted in a frequency dependent significant increase in oxidative stress markers viz. malondialdehyde (MDA), protein carbonyl (PCO) and catalase (CAT) in microwave exposed groups in comparison to sham exposed group (pmicrowave exposed groups (pmicrowave exposed animal (pmicrowave exposed groups as compared to their corresponding values in sham exposed group (pmicrowave radiation induces oxidative stress, inflammatory response and DNA damage in brain by exerting a frequency dependent effect. The study also indicates that increased oxidative stress and inflammatory response might be the factors involved in DNA damage following low intensity microwave exposure. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Thinner inhalation effects on oxidative stress and DNA repair in a rat model of abuse.

    Martínez-Alfaro, Minerva; Cárabez-Trejo, Alfonso; Gallegos-Corona, Marco-Antonio; Pedraza-Aboytes, Gustavo; Hernández-Chan, Nancy Georgina; Leo-Amador, Guillermo Enrique

    2010-04-01

    Humans can come into contact with thinner by occupational exposure or by intentional inhalation abuse. Numerous studies of workers for genotoxic effects of thinner exposure have yielded conflicting results, perhaps because co-exposure to variable other compounds cannot be avoided in workplace exposure studies. In contrast, there is no data concerning the genotoxic effects of intentional inhalation abuse. The aim of this project was to examine the genotoxic effects of thinner inhalation in an animal model of thinner abuse (rats exposed to 3000 ppm toluene, a high solvent concentration over a very short, 15 min time period, twice a day for 6 weeks). The data presented here provides evidence that thinner inhalation in our experimental conditions is able to induce weight loss, lung abnormalities and oxidative stress. This oxidative stress induces oxidative DNA damage that is not a characteristic feature of genotoxic damage. No significant difference in DNA damage and DNA repair (biomarkers of genotoxicity) in lymphocytes from thinner-treated and control rats was found. Lead treatment was used as a positive control in these assays. Finally, bone marrow was evaluated as a biomarker of cellular alteration associated with thinner inhalation. The observed absence of hemopoietic and genetic toxicity could be explained in part by the absence of benzene, the only carcinogenic component of thinner; however, benzene is no longer a common component of thinner. In conclusion, thinner did not cause genotoxic effects in an experimental model of intentional abuse despite the fact that thinner inhalation induces oxidative stress. (c) 2009 John Wiley & Sons, Ltd.

  1. DNA degradation in genetically modified rice with Cry1Ab by food processing methods: implications for the quantification of genetically modified organisms.

    Xing, Fuguo; Zhang, Wei; Selvaraj, Jonathan Nimal; Liu, Yang

    2015-05-01

    Food processing methods contribute to DNA degradation, thereby affecting genetically modified organism detection and quantification. This study evaluated the effect of food processing methods on the relative transgenic content of genetically modified rice with Cry1Ab. In steamed rice and rice noodles, the levels of Cry1Ab were ⩾ 100% and <83%, respectively. Frying and baking in rice crackers contributed to a reduction in Pubi and Cry1Ab, while microwaving caused a decrease in Pubi and an increase in Cry1Ab. The processing methods of sweet rice wine had the most severe degradation effects on Pubi and Cry1Ab. In steamed rice and rice noodles, Cry1Ab was the most stable, followed by SPS and Pubi. However, in rice crackers and sweet rice wine, SPS was the most stable, followed by Cry1Ab and Pubi. Therefore, Cry1Ab is a better representative of transgenic components than is Pubi because the levels of Cry1Ab were less affected compared to Pubi. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Default cycle phases determined after modifying discrete DNA sequences in plant cells

    Sans, J.; Leyton, C.

    1997-01-01

    After bromosubstituting DNA sequences replicated in the first, second, or third part of the S phase, in Allium cepa L. meristematic cells, radiation at 313 nm wavelength under anoxia allowed ascription of different sequences to both the positive and negative regulation of some cycle phase transitions. The present report shows that the radiation forced cells in late G 1 phase to advance into S, while those in G 2 remained in G 2 and cells in prophase returned to G 2 when both sets of sequences involved in the positive and negative controls were bromosubstituted and later irradiated. In this way, not only G 2 but also the S phase behaved as cycle phases where cells accumulated by default when signals of different sign functionally cancelled out. The treatment did not halt the rates of replication or transcription of plant bromosubstituted DNA. The irradiation under hypoxia apparently prevents the binding of regulatory proteins to Br-DNA. (author)

  3. Detection of NADH via electrocatalytic oxidation at single-walled carbon nanotubes modified with Variamine blue

    Radoi, A.; Compagnone, D.; Valcarcel, M.A.; Placidi, P.; Materazzi, S.; Moscone, D.; Palleschi, G.

    2008-01-01

    Screen-printed electrodes (SPEs) modified with Variamine blue (VB), covalently attached to the oxidized single-walled carbon nanotubes (SWCNTs-COOH), were developed and used as chemical sensors for the detection of the reduced nicotinamide adenine dinucleotide (NADH). The Variamine blue redox mediator was covalently linked to the SWCNTs-COOH by the N,N'-dicyclohexylcarbodiimide (DCC) and N-hydroxysuccinimide (NHS) chemistry. Infrared Fourier transform (FT-IR) spectroscopy revealed the presence of the amide bands situated at 1623 cm -1 (I band), 1577 cm -1 (II band) and 1437 cm -1 (III band) demonstrating the covalent linkage of Variamine blue to SWCNTs-COOH. The heterogeneous electron transfer rate, k obs. , was 13,850 M -1 s -1 , and the k s and α were 0.8 s -1 and 0.56, respectively. The pH dependence was also investigated. SPEs modified with Variamine blue by using the DCC/NHS conjugation method, showed a variation of -36 mV per pH unit. A successful application was the development of a lactate biosensor obtained by the immobilization of the L-lactate dehydrogenase on the NADH sensor

  4. Surface treatment of NiTi shape memory alloy by modified advanced oxidation process

    CHU Cheng-lin; WANG Ru-meng; YIN Li-hong; PU Yue-pu; DONG Yin-sheng; GUO Chao; SHENG Xiao-bo; LIN Ping-hua; CHU Paul-K

    2009-01-01

    A modified advanced oxidation process(AOP) utilizing a UV/electrochemically-generated peroxide system was used to fabricate titania films on chemically polished NiTi shape memory alloy(SMA). The microstructure and biomedical properties of the film were characterized by scanning electron microscopy(SEM), X-ray photoelectron spectroscopy(XPS), inductively-coupled plasma mass spectrometry(ICPMS), hemolysis analysis, and blood platelet adhesion test. It is found that the modified AOP has a high processing effectiveness and can result in the formation of a dense titania film with a Ni-free zone near its top surface. In comparison, Ni can still be detected on the outer NiTi surface by the conventional AOP using the UV/H2O2 system. The depth profiles of O, Ni, Ti show that the film possesses a smooth graded interface structure next to the NiTi substrate and this structure enhances the mechanical stability of titania film. The titania film can dramatically reduce toxic Ni ion release and also improve the hemolysis resistance and thromboresistance of biomedical NiTi SMA.

  5. Adhesion mapping of chemically modified and poly(ethylene oxide)-grafted glass surfaces.

    Jogikalmath, G; Stuart, J K; Pungor, A; Hlady, V

    1999-08-01

    Two-dimensional mapping of the adhesion pull-off forces was used to study the origin of surface heterogeneity in the grafted poly(ethylene oxide) (PEO) layer. The variance of the pull-off forces measured over the μm-sized regions after each chemical step of modifying glass surfaces was taken to be a measure of the surface chemical heterogeneity. The attachment of γ-glycidoxypropyltrimethoxy silane (GPS) to glass decreased the pull-off forces relative to the clean glass and made the surface more uniform. The subsequent hydrolysis of the terminal epoxide groups resulted in a larger surface heterogeneity which was modeled by two populations of the terminal hydroxyl groups, each with its own distribution of adhesion forces and force variance. The activation of the hydroxyls with carbonyldiimmidazole (CDI) healed the surface and lowered its adhesion, however, the force variance remained rather large. Finally, the grafting of the α,ω-diamino poly(ethyleneoxide) chains to the CDI-activated glass largely eliminated adhesion except at a few discrete regions. The adhesion on the PEO grafted layer followed the Poisson distribution of the pull-off forces. With the exception of the glass surface, a correlation between the water contact angles and the mean pull-off forces measured with the Si(3)N(4) tip surfaces was found for all modified glass surfaces.

  6. Surface-modified anodic aluminum oxide membrane with hydroxyethyl celluloses as a matrix for bilirubin removal.

    Xue, Maoqiang; Ling, Yisheng; Wu, Guisen; Liu, Xin; Ge, Dongtao; Shi, Wei

    2013-01-01

    Microporous anodic aluminum oxide (AAO) membranes were modified by 3-glycidoxypropyltrimethoxysilane to produce terminal epoxy groups. These were used to covalently link hydroxyethyl celluloses (HEC) to amplify reactive groups of AAO membrane. The hydroxyl groups of HEC-AAO composite membrane were further modified with 1,4-butanediol diglycidyl ether to link arginine as an affinity ligand. The contents of HEC and arginine of arginine-immobilized HEC-AAO membrane were 52.1 and 19.7mg/g membrane, respectively. As biomedical adsorbents, the arginine-immobilized HEC-AAO membranes were tested for bilirubin removal. The non-specific bilirubin adsorption on the unmodified HEC-AAO composite membranes was 0.8mg/g membrane. Higher bilirubin adsorption values, up to 52.6mg/g membrane, were obtained with the arginine-immobilized HEC-AAO membranes. Elution of bilirubin showed desorption ratio was up to 85% using 0.3M NaSCN solution as the desorption agent. Comparisons equilibrium and dynamic capacities showed that dynamic capacities were lower than the equilibrium capacities. In addition, the adsorption mechanism of bilirubin and the effects of temperature, initial concentration of bilirubin, albumin concentration and ionic strength on adsorption were also investigated. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Non-enzymatic glucose sensing platform using self assembled cobalt oxide/graphene nanocomposites immobilized graphite modified electrode

    Vivekananth, R.; Babu, R. Suresh; Prasanna, K.

    2018-01-01

    A new strategy to prepare the densely packed cobalt oxide (Co3O4)/graphene nanocomposites by a self-assembly method were adopted in this work. A new non-enzymatic glucose determination has been fabricated by using Co3O4/graphene nanocomposites modified electrode as a sensing material. The nanocom...... of the modified electrode for glucose determination has been evaluated in urine samples....

  8. Chemically-modified electrodes in photoelectrochemical cells. [Tin oxide and TiO/sub 2/ semiconductor electrodes

    Fox, M A; Hohman, J R; Kamat, P V

    1893-01-01

    Tin oxide and titanium dioxide semiconductor electrodes hae been covalently modified by the attachment of functionalized olefins and arenes through surface silanation or via a cyanuric chloride linkage. The excited state and electrochemical properties of the molecules so attached are significantly affected by the semiconductor. Photocurrent measurements and time-resolved laser coulostatic monitoring have been employed to elucidate the mechanism of charge injection on these modified surfaces. 17 references, 7 figures.

  9. Modified graphene oxide sensors for ultra-sensitive detection of nitrate ions in water.

    Ren, Wen; Mura, Stefania; Irudayaraj, Joseph M K

    2015-10-01

    Nitrate ions is a very common contaminant in drinking water and has a significant impact on the environment, necessitating routine monitoring. Due to its chemical and physical properties, it is hard to directly detect nitrate ions with high sensitivity in a simple and inexpensive manner. Herein with amino group modified graphene oxide (GO) as a sensing element, we show a direct and ultra-sensitive method to detect nitrate ions, at a lowest detected concentration of 5 nM in river water samples, much lower than the reported methods based on absorption spectroscopy. Furthermore, unlike the reported strategies based on absorption spectroscopy wherein the nitrate concentration is determined by monitoring an increase in aggregation of gold nanoparticles (GNPs), our method evaluates the concentration of nitrate ions based on reduction in aggregation of GNPs for monitoring in real samples. To improve sensitivity, several optimizations were performed, including the assessment of the amount of modified GO required, concentration of GNPs and incubation time. The detection methodology was characterized by zeta potential, TEM and SEM. Our results indicate that an enrichment of modified GO with nitrate ions contributed to excellent sensitivity and the entire detection procedure could be completed within 75 min with only 20 μl of sample. This simple and rapid methodology was applied to monitor nitrate ions in real samples with excellent sensitivity and minimum pretreatment. The proposed approach paves the way for a novel means to detect anions in real samples and highlights the potential of GO based detection strategy for water quality monitoring. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Curcumin protects against cytotoxic and inflammatory effects of quartz particles but causes oxidative DNA damage in a rat lung epithelial cell line

    Li Hui; Berlo, Damien van; Shi Tingming; Speit, Guenter; Knaapen, Ad M.; Borm, Paul J.A.; Albrecht, Catrin; Schins, Roel P.F.

    2008-01-01

    Chronic inhalation of high concentrations of respirable quartz particles has been implicated in various lung diseases including lung fibrosis and cancer. Generation of reactive oxygen species (ROS) and oxidative stress is considered a major mechanism of quartz toxicity. Curcumin, a yellow pigment from Curcuma longa, has been considered as nutraceutical because of its strong anti-inflammatory, antitumour and antioxidant properties. The aim of our present study was to investigate whether curcumin can protect lung epithelial cells from the cytotoxic, genotoxic and inflammatory effects associated with quartz (DQ12) exposure. Electron paramagnetic resonance (EPR) measurements using the spin-trap DMPO demonstrated that curcumin reduces hydrogen peroxide-dependent hydroxyl-radical formation by quartz. Curcumin was also found to reduce quartz-induced cytotoxicity and cyclooxygenase 2 (COX-2) mRNA expression in RLE-6TN rat lung epithelial cells (RLE). Curcumin also inhibited the release of macrophage inflammatory protein-2 (MIP-2) from RLE cells as observed upon treatment with interleukin-1 beta (IL-1β) and tumour necrosis factor-alpha (TNFα). However, curcumin failed to protect the RLE cells from oxidative DNA damage induced by quartz, as shown by formamidopyrimidine glycosylase (FPG)-modified comet assay and by immunocytochemistry for 8-hydroxydeoxyguanosine. In contrast, curcumin was found to be a strong inducer of oxidative DNA damage itself at non-cytotoxic and anti-inflammatory concentrations. In line with this, curcumin also enhanced the mRNA expression of the oxidative stress response gene heme oxygenase-1 (ho-1). Curcumin also caused oxidative DNA damage in NR8383 rat alveolar macrophages and A549 human lung epithelial cells. Taken together, these observations indicate that one should be cautious in considering the potential use of curcumin in the prevention or treatment of lung diseases associated with quartz exposure

  11. Improvement of the stability and activity of immobilized glucose oxidase on modified iron oxide magnetic nanoparticles

    Abbasi, Mahboube; Amiri, Razieh; Bordbar, Abdol-Kalegh; Ranjbakhsh, Elnaz; Khosropour, Ahmad-Reza

    2016-02-01

    Immobilized proteins and enzymes are widely investigated in the medical field as well as the food and environmental fields. In this study, glucose oxidase (GOX) was covalently immobilized on the surface of modified iron oxide magnetic nanoparticles (MIMNs) to produce a bioconjugate complex. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to the size, shape and structure characterization of the MIMNs. Binding of GOX to these MIMNs was confirmed by using FT-IR spectroscopy. The stability of the immobilized and free enzyme at different temperature and pH values was investigated by measuring the enzymatic activity. These studies reveal that the enzyme's stability is enhanced by immobilization. Further experiments showed that the storage stability of the enzyme is improved upon binding to the MIMNs. The results of kinetic measurements suggest that the effect of the immobilization process on substrate and product diffusion is small. Such bioconjugates can be considered as a catalytic nanodevice for accelerating the glucose oxidation reaction for biotechnological purposes.

  12. Urea impedimetric biosensing using electrospun nanofibers modified with zinc oxide nanoparticles

    Migliorini, Fernanda L.; Sanfelice, Rafaela C.; Mercante, Luiza A.; Andre, Rafaela S.; Mattoso, Luiz H. C.; Correa, Daniel. S.

    2018-06-01

    Reliable analytical techniques to evaluate dairy products, including milk, are of outmost importance to ensure food safety against contaminants. Among possible substances employed as adulterants in milk, urea raises deep concern due to its harmful effects to consumer's health. In the present study, a biosensing platform was developed to be applied in the electrochemical detection of urea. The sensing platform was fabricated using polymeric electrospun nanofibers of polyamide 6 (PA6) and polypyrrole (PPy) deposited onto fluorine doped tin oxide (FTO) electrodes, which were then modified with zinc oxide nanoparticles (ZnO). This material showed excellent properties for the immobilization of urease enzyme, conferring the FTO/PA6/PPy/ZnO/urease electrode high sensitivity for urea detection within the concentration range between 0.1 and 250 mg dL-1 with a limit of detection of 0.011 mg dL-1. The results achieved evidence the potential of electrospun nanofibers-based electrodes for applications in biosensors aiming at dairy products analysis.

  13. Preparation of ionic liquid-modified SBA-15 doped with molybdovanadophosphoric acid for oxidative desulfurization

    Zhuang, Jiang Zhou; Jin, Xiao Yin; Shen, Xian Lin; Tan, Jun Jun; Nie, Long Hui; Xiang, Jian; Hu, Bing

    2015-01-01

    A series of catalysts, ionic liquid-modified SBA-15 (denoted ILSBA) doped with H 5 PMo 10 V 2 O 40 (HPMoV 2 ) have been synthesized and characterized by XRD, FT-IR, 1 H NMR, TG-DTA, and TEM. The catalyst was used for the removal of dibenzothiophene (DBT) in model oil combined with hydrogen peroxide (the oxidant) and acetonitrile (the phase-transfer agent). It was observed that the sulfur content of DBT can be reduced from 500 to 2 ppm by adjusting the amount of catalyst, the reaction temperatures and the reaction time. Besides, the catalyst activity for different sulfur compounds showed a huge difference which may be mainly affected by the electron densities of sulfur atom. Moreover, the catalyst can be recycled seven times without a significant loss in activity, which could be ascribed to the strong electrostatic interaction between ILSBA and HPMoV 2 . In addition, a postulated mechanism was proposed to reveal the oxidative desulfurization process

  14. Preparation of ionic liquid-modified SBA-15 doped with molybdovanadophosphoric acid for oxidative desulfurization

    Zhuang, Jiang Zhou; Jin, Xiao Yin; Shen, Xian Lin; Tan, Jun Jun; Nie, Long Hui; Xiang, Jian; Hu, Bing [Dept. of chool of Chemistry and Chemical Engineering, Hubei University of Technology, Wuhan (China)

    2015-07-15

    A series of catalysts, ionic liquid-modified SBA-15 (denoted ILSBA) doped with H{sub 5}PMo{sub 10}V{sub 2}O{sub 40} (HPMoV{sub 2}) have been synthesized and characterized by XRD, FT-IR, {sup 1}H NMR, TG-DTA, and TEM. The catalyst was used for the removal of dibenzothiophene (DBT) in model oil combined with hydrogen peroxide (the oxidant) and acetonitrile (the phase-transfer agent). It was observed that the sulfur content of DBT can be reduced from 500 to 2 ppm by adjusting the amount of catalyst, the reaction temperatures and the reaction time. Besides, the catalyst activity for different sulfur compounds showed a huge difference which may be mainly affected by the electron densities of sulfur atom. Moreover, the catalyst can be recycled seven times without a significant loss in activity, which could be ascribed to the strong electrostatic interaction between ILSBA and HPMoV{sub 2}. In addition, a postulated mechanism was proposed to reveal the oxidative desulfurization process.

  15. Enhanced electrochemical oxidation of methanol on copper electrodes modified by electrocorrosion and electrodeposition

    Carugno, Sofía [INQUIMAE – DQIAQF, Facultad de Ciencias, Exactas y Naturales, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, 1428 Buenos Aires (Argentina); Chassaing, Elisabeth [IRDEP (UMR7174), EDF R and D, 6 Quai Watier, 78401 Chatou (France); Rosso, Michel [LPMC (UMR7643), CNRS, Ecole Polytechnique, F91128 Palaiseau Cedex (France); González, Graciela A., E-mail: graciela@qi.fcen.uba.ar [INQUIMAE – DQIAQF, Facultad de Ciencias, Exactas y Naturales, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, 1428 Buenos Aires (Argentina)

    2014-02-14

    In this paper, we report a study of electrocatalytic oxidation of methanol on copper electrodes subjected to different surface treatments, either electrocorrosion or electrodeposition in the absence of strong hydrogen co-deposition. The surface morphology of treated electrodes was examined by Field Emission Scanning Electron Microscopy (FE-SEM). The effect of different treatment conditions and the methanol concentration dependence were evaluated by cyclic voltammetric technique. The results indicate that the oxidation of methanol can be enhanced by a suitable micro and nano structure generated by these treatments. This enhanced electrode activity is related to an increase of the effective surface area and/or to an increase of the surface concentration of electroactive molecules or intermediates. - Highlights: • We presented simple treatments to increase the response of copper electrodes. • Copper electrodes were modified by electrocorrosion and electrodeposition. • Scanning Electron Microscopy images reveal the effects of the different treatments. • The response is enhanced by an area increase and/or intermediates concentration. • For each treatment the concentration range of the diffusion control is analyzed.

  16. Carbon monoxide oxidation on a Au(111 surface modified by spontaneously deposited Ru

    ROLF-JÜRGEN BEHM

    2001-04-01

    Full Text Available The spontaneous deposition of Ru on Au(111 was performed in 10-3 M RuCl3 + 0.5 M H2SO4 solution. The obtained surface was characterized by STM under potential control in 0.5 M H2SO4 solution. The coverage of the Au(111 terraces by deposited Ru was estimated by STM to be 0.02 ML. Step decoration could be noticed in the STM images, which indicates that the steps, as lined defects, are active sites for the nucleation of Ru monolayer islands, while the random distribution of Ru nuclei, observed on the terraces indicates point defects as active sites. The electrocatalytic activity of Au(111 surface modified by spontaneously deposited Ru was studied towards CO oxidation. The significant enhancement in the reaction rate compared to CO oxidation on a pure Au(111 surface, indicated that the edges of the deposited Ru islands were the active sites for the reaction.

  17. Modified and improved Hummer's synthesis of graphene oxide for capacitors applications

    M. Sohail

    2017-09-01

    Full Text Available In the present study, we explored whether different characteristics of graphene oxide prepared via two different routes have been modified. It was observed that samples obtained via both routes have nearly the same physico-chemical characteristics. Spectral (FT-IR and UV-vis studies showed the synthesis and optical properties of the materials respectively. Optical band gap (Eg was found to be in the range of 3.1–3.9 eV. Thermal studies demonstrated that the prepared materials exhibited stability up to 550 °C. X-ray diffraction evaluated the semi-crystalline nature of the materials with crystallite size in the range from 27–28 nm. Dielectric study showed that the materials are active at low frequency range due to interfacial polarization while at higher frequency the dipoles present in the materials show relaxation behavior. The lowest value of dielectric tan. loss (0.03–0.39 acquired by both the samples is of immense importance for capacitors. Based on the observations, graphene oxide prepared is suggested to be used a possible material in thermally stable capacitors and in composite materials.

  18. Preparation and Application of Water-in-Oil Emulsions Stabilized by Modified Graphene Oxide

    Xiaoma Fei

    2016-08-01

    Full Text Available A series of alkyl chain modified graphene oxides (AmGO with different alkyl chain length and content was fabricated using a reducing reaction between graphene oxide (GO and alkyl amine. Then AmGO was used as a graphene-based particle emulsifier to stabilize Pickering emulsion. Compared with the emulsion stabilized by GO, which was oil-in-water type, all the emulsions stabilized by AmGO were water-in-oil type. The effects of alkyl chain length and alkyl chain content on the emulsion properties of AmGO were investigated. The emulsions stabilized by AmGO showed good stability within a wide range of pH (from pH = 1 to pH = 13 and salt concentrations (from 0.1 to 1000 mM. In addition, the application of water-in-oil emulsions stabilized by AmGO was investigated. AmGO/polyaniline nanocomposite (AmGO/PANi was prepared through an emulsion approach, and its supercapacitor performance was investigated. This research broadens the application of AmGO as a water-in-oil type emulsion stabilizer and in preparing graphene-based functional materials.

  19. Methanol electro-oxidation on Pt/C modified by polyaniline nanofibers for DMFC applications

    Zhiani, Mohammad; Rezaei, Behzad; Jalili, Jalal [Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111 (Iran)

    2010-09-15

    In the present study, in order to achieve an inexpensive tolerable anode catalyst for direct methanol fuel cell applications, a composite of polyaniline nanofibers and Pt/C nano-particles, identified by PANI/Pt/C, was prepared by in-situ electropolymerization of aniline and trifluoromethane sulfonic acid on glassy carbon. The effect of synthesized PANI nanofibers in methanol electrooxidation reaction was compared by bare Pt/C by different electrochemical methods such as; cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry. Scanning electron microscopy (SEM) was also employed to morphological study of the modified catalyst layer. The test results reveal that introduction of PANI nanofibers within catalyst layer improves the catalyst activity in methanol oxidation, hinders and prevents catalyst from more poisoning by intermediate products of methanol oxidation and improves the mechanical properties of the catalyst layer. SEM images also indicate that PANI nanofibers placed between platinum particles and anchor platinum particles and alleviate the Pt migration during methanol electrooxidation. (author)

  20. Electrochemical Glucose Oxidation Using Glassy Carbon Electrodes Modified with Au-Ag Nanoparticles: Influence of Ag Content

    Nancy Gabriela García-Morales

    2015-01-01

    Full Text Available This paper describes the application of glassy carbon modified electrodes bearing Aux-Agy nanoparticles to catalyze the electrochemical oxidation of glucose. In particular, the paper shows the influence of the Ag content on this oxidation process. A simple method was applied to prepare the nanoparticles, which were characterized by transmission electron microscopy, Ultraviolet-Visible spectroscopy, X-ray diffraction spectroscopy, and cyclic voltammetry. These nanoparticles were used to modify glassy carbon electrodes. The effectiveness of these electrodes for electrochemical glucose oxidation was evaluated. The modified glassy carbon electrodes are highly sensitive to glucose oxidation in alkaline media, which could be attributed to the presence of Aux-Agy nanoparticles on the electrode surface. The voltammetric results suggest that the glucose oxidation speed is controlled by the glucose diffusion to the electrode surface. These results also show that the catalytic activity of the electrodes depends on the Ag content of the nanoparticles. Best results were obtained for the Au80-Ag20 nanoparticles modified electrode. This electrode could be used for Gluconic acid (GA production.

  1. Grape (Vitis vinifera) extracts protect against radiation-induced oxidative stress and DNA damage

    Singha, Indrani; Das, Subir Kumar; Saxena, S.; Gautam, S.

    2016-01-01

    Ionizing radiation (IR) causes oxidative stress through the overwhelming generation of reactive oxygen species (ROS) in the living cells leading further to the oxidative damage to biomolecules. Grapes (Vitis vinifera) contain several bioactive phytochemicals and are the richest source of antioxidant. In this study, we investigated and compared in vitro antioxidant activity and DNA damage protective property of the grape extracts of four different cultivars, including the Thompson seedless, Flame seedless, Kishmish chorni and Red globe. The activities of ascorbic acid oxidase and catalase significantly (p<0.01) differed among extracts within the same cultivar, while that of peroxidase and polyphenol oxidase did not differ significantly among extracts of any cultivar. In vitro antioxidant activities were assessed by ferric-reducing antioxidant power (FRAP) assay and ABTS. The superoxide radical-scavenging activity was higher in the seed as compared to the skin or pulp of the same cultivar. DNA damage was evaluated in acellular system using pBR322 plasmid relaxation. Grape extract was able to effectively scavenge free radicals in vitro. It could significantly prevent radiation-induced DNA damage. Furthermore, the protective action of grape depends on the source of extract and type of the cultivars. (author)

  2. Nano Copper Oxide-Modified Carbon Cloth as Cathode for a Two-Chamber Microbial Fuel Cell

    Dong, Feng; Zhang, Peng; Li, Kexun; Liu, Xianhua; Zhang, Pingping

    2016-01-01

    In this work, Cu2O nanoparticles were deposited on a carbon cloth cathode using a facile electrochemical method. The morphology of the modified cathode, which was characterized by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) tests, showed that the porosity and specific surface area of the cathode improved with longer deposition times. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) results showed that cupric oxide and cuprous oxide coexisted on the ca...

  3. Nano-structured Ni(II)-curcumin modified glassy carbon electrode for electrocatalytic oxidation of fructose

    Elahi, M. Yousef; Mousavi, M.F.; Ghasemi, S.

    2008-01-01

    A nano-structured Ni(II)-curcumin (curcumin: 1,7-bis[4-hydroxy-3-methoxyphenyl]-1,6-heptadiene-3,5-dione) film is electrodeposited on a glassy carbon electrode in alkaline solution. The morphology of polyNi(II)-curcumin (NC) was investigated by scanning electron microscopy (SEM). The SEM results show NC has a nano-globular structure in the range 20-50 nm. Using cyclic voltammetry, linear sweep voltammetry, chronoamperometry, steady-state polarization measurements and electrochemical impedance spectroscopy (EIS) showed that the nano-structure NC film acts as an efficient material for the electrocatalytic oxidation of fructose. According to the voltammetric studies, the increase in the anodic peak current and subsequent decrease in the corresponding cathodic current, fructose was oxidized on the electrode surface via an electrocatalytic mechanism. The EIS results show that the charge-transfer resistance has as a function of fructose concentration, time interval and applied potential. The increase in the fructose concentration and time interval in fructose solution results in enhanced charge transfer resistance in Nyquist plots. The EIS results indicate that fructose electrooxidation at various potentials shows different impedance behaviors. At lower potentials, a semicircle is observed in the first quadrant of impedance plot. With further increase of the potential, a transition of the semicircle from the first to the second quadrant occurs. Also, the results obtained show that the rate of fructose electrooxidation depends on concentration of OH - . Electron transfer coefficient, diffusion coefficient and rate constant of the electrocatalytic oxidation reaction are obtained. The modified electrode was used as a sensor for determination of fructose with a good dynamic range and a low detection limit

  4. Novel KMnO4-modified iron oxide for effective arsenite removal

    Huang, Yao-Hui; Shih, Yu-Jen; Cheng, Fu-Ji

    2011-01-01

    Highlights: ► We employ the MnBT-4 adsorbent for As (III)/(V) removal in solution. ► The waste iron oxide BT-4 acts as the support to immobilize Mn using FBR reactor. ► MnBT-4 has higher arsenite adsorption as compared with BT4. ► Easy solid–liquid separation and cost effective are the merits of applying MnBT-4. - Abstract: This work demonstrates the synthesis of a novel KMnO 4 -modified form of iron oxide, MnBT-4, using a fluidized bed reactor (FBR) for the adsorptive removal of arsenic (III)/(V). Characterization by XRD, BET, and SEM indicated that the BT-4 support was poorly crystallized goethite (α-FeOOH) with a specific surface area of 229 m 2 g −1 . In FBR experiments of synthesizing MnBT-4, the Fe and Mn salts were found to have an optimal dosage ratio of less than 4, which maximized the KMnO 4 immobilization efficiency. The immobilized Mn compounds on MnBT-4 underwent an additional oxidation step of As (III), promoting arsenic adsorption. When applied MnBT-4 for As (III) removal from solution, the sorption isotherm was accurately fitted with Langmuir and Freundlich models, while the maximum adsorption capacity of 27.4 mg g −1 exceeded those of other adsorbents in the literature. Batch experimental results revealed that both raw BT-4 and MnBT-4 could take up a large amount of As (V). However, the MnBT-4 provided a substantially higher As (III) removal efficiency than BT-4.

  5. Hydrous iron oxide modified diatomite as an active filtration medium for phosphate capture.

    Wang, Zhe; Lin, Yan; Wu, Deyi; Kong, Hainan

    2016-02-01

    A simple method to functionalize diatomite with hydrous iron oxide was attempted and its performance as a new active filtration material to remove and recover phosphate from water was investigated under varying solution conditions. The Langmuir phosphate adsorption capacity increased from 0.6 mgP/g for raw diatomite to 4.89, 14.71, 25.02 mgP/g for hydrous iron oxide modified diatomite (HIOMD), depending on the amount of iron loaded. Loading of hydrous iron oxide caused the increase in true and bulk density and a decline in filtration rate, but to a lesser extent. It was shown that the HIOMD product with suitable iron content could retain a good filtration performance with a greatly increased adsorption capacity for phosphate. The phosphate adsorption increased by decreasing pH and by increasing ionic strength at high pH levels. The adsorption process was interpreted by ligand exchange. Coexisting oxyanions of sulfate, nitrate, citrate, carbonate, silicate and humic acid showed different effects on phosphate fixation but it was presumed that their influence at their concentrations and pH levels commonly encountered in effluent or natural waters was limited, i.e., HIOMD had a reasonably good selectivity. Results in repeated adsorption, desorption and regeneration experiment showed that the adsorbed phosphate could be recovered and the material could be reused after regeneration. The column test showed that HIOMD could be potentially utilized as an adsorption filtration medium for phosphate removal and recovery from water. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Detection of genetically modified organisms (GMOs using isothermal amplification of target DNA sequences

    La Mura Maurizio

    2009-02-01

    Full Text Available Abstract Background The most common method of GMO detection is based upon the amplification of GMO-specific DNA amplicons using the polymerase chain reaction (PCR. Here we have applied the loop-mediated isothermal amplification (LAMP method to amplify GMO-related DNA sequences, 'internal' commonly-used motifs for controlling transgene expression and event-specific (plant-transgene junctions. Results We have tested the specificity and sensitivity of the technique for use in GMO studies. Results show that detection of 0.01% GMO in equivalent background DNA was possible and dilutions of template suggest that detection from single copies of the template may be possible using LAMP. Conclusion This work shows that GMO detection can be carried out using LAMP for routine screening as well as for specific events detection. Moreover, the sensitivity and ability to amplify targets, even with a high background of DNA, here demonstrated, highlights the advantages of this isothermal amplification when applied for GMO detection.

  7. Synthesis of Hydrazone-Modified Nucleotides and Their Polymerase Incorporation onto DNA for Redox Labeling

    Raindlová, Veronika; Pohl, Radek; Klepetářová, Blanka; Havran, Luděk; Šimková, Eva; Horáková Brázdilová, Petra; Pivoňková, Hana; Fojta, Miroslav; Hocek, Michal

    2012-01-01

    Roč. 77, č. 8 (2012), s. 652-662 ISSN 2192-6506 R&D Projects: GA AV ČR(CZ) IAA400040901; GA ČR GBP206/12/G151 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50040702 Keywords : DNA * oligonucleotides * polymerase * hydrazones * nucleotides Subject RIV: CC - Organic Chemistry

  8. DNA polymorphism sensitive impedimetric detection on gold-nanoislands modified electrodes.

    Bonanni, Alessandra; Pividori, Maria Isabel; del Valle, Manel

    2015-05-01

    Nanocomposite materials are being increasingly used in biosensing applications as they can significantly improve biosensor performance. Here we report the use of a novel impedimetric genosensor based on gold nanoparticles graphite-epoxy nanocomposite (nanoAu-GEC) for the detection of triple base mutation deletion in a cystic-fibrosis (CF) related human DNA sequence. The developed platform consists of chemisorbing gold nano-islands surrounded by rigid, non-chemisorbing, and conducting graphite-epoxy composite. The ratio of the gold nanoparticles in the composite was carefully optimized by electrochemical and microscopy studies. Such platform allows the very fast and stable thiol immobilization of DNA probes on the gold islands, thus minimizing the steric and electrostatic repulsion among the DNA probes and improving the detection of DNA polymorphism down to 2.25fmol by using electrochemical impedance spectroscopy. These findings are very important in order to develop new and renewable platforms to be used in point-of-care devices for the detection of biomolecules. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Consequences of low birthweight on urinary excretion of DNA markers of oxidative stress in young men

    Hillestrøm, P R; Weimann, A; Jensen, C B

    2006-01-01

    OBJECTIVE: Low birthweight (LBW) has been associated with an increased risk of development of type 2 diabetes in adult life. Both type 1 and type 2 diabetes mellitus are characterized by increased oxidative stress. The purpose of this study was to investigate whether young healthy adults born...... with LBW showed differences in oxidative stress under normal conditions and during the added challenge of a physiological Intralipid infusion. MATERIAL AND METHODS: Urinary excretion of DNA markers of oxidative stress were analyzed by LC-MS/MS in 19 men (aged 19 years) with LBW and in 19 age matched...... with LBW and NBW (66.9 versus 73.9 nmol/15 h, 17.8 versus 18.5 nmol/15 h, 11.9 versus 14.4 nmol/15 h and 44.0 versus 43.2 pmol/15 h, respectively). Furthermore, Intralipid infusion did not affect excretion of DNA adducts in LBW or NBW subjects. Statistically significant correlations were found between body...

  10. Development of Ionic Liquid Modified Disposable Graphite Electrodes for Label-Free Electrochemical Detection of DNA Hybridization Related to Microcystis spp.

    Ceren Sengiz

    2015-09-01

    Full Text Available In this present study, ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate (IL modified pencil graphite electrode (IL-PGEs was developed for electrochemical monitoring of DNA hybridization related to Microcystis spp. (MYC. The characterization of IL-PGEs was performed using microscopic and electrochemical techniques. DNA hybridization related to MYC was then explored at the surface of IL-PGEs using differential pulse voltammetry (DPV technique. After the experimental parameters were optimized, the sequence-selective DNA hybridization related to MYC was performed in the case of hybridization between MYC probe and its complementary DNA target, noncomplementary (NC or mismatched DNA sequence (MM, or and in the presence of mixture of DNA target: NC (1:1 and DNA target: MM (1:1.

  11. Oxidative Stress Induced Lipid Peroxidation And DNA Adduct Formation In The Pathogenesis Of Multiple Myeloma And Lymphoma

    Tandon, Ravi

    2013-02-01

    Full Text Available Objective: To access the oxidative stress status by quantification of byproducts generated during lipid peroxidation and DNA breakdown products generated during DNA damage in the blood serum of multiple myeloma and lymphoma patients.Material & Methods: Case control study comprised of 40 patients of multiple myeloma and 20 patients of lymphoma along with 20 age and sex-matched healthy subjects as controls. Levels of Malondialdehyde and 8-hydroxy-2-deoxy-Guanosine were measured to study the oxidative stress status in the study subjects.Results: The level of markers of DNA damage and lipid peroxidation were found to be raised significantly in the study subjects in comparison to healthy controls. The results indicate oxidative stress and DNA damage activity increase progressively with the progression of disease.Conclusion: Oxidative stress causes DNA damage and Lipid peroxidation which results in the formation of DNA adducts leading to mutations thereby indicate the role of oxidative stress in the pathogenesis of multiple myeloma and lymphoma.

  12. Is There Still Any Role for Oxidative Stress in Mitochondrial DNA-Dependent Aging?

    Gábor Zsurka

    2018-03-01

    Full Text Available Recent deep sequencing data has provided compelling evidence that the spectrum of somatic point mutations in mitochondrial DNA (mtDNA in aging tissues lacks G > T transversion mutations. This fact cannot, however, be used as an argument for the missing contribution of reactive oxygen species (ROS to mitochondria-related aging because it is probably caused by the nucleotide selectivity of mitochondrial DNA polymerase γ (POLG. In contrast to point mutations, the age-dependent accumulation of mitochondrial DNA deletions is, in light of recent experimental data, still explainable by the segregation of mutant molecules generated by the direct mutagenic effects of ROS (in particular, of HO· radicals formed from H2O2 by a Fenton reaction. The source of ROS remains controversial, because the mitochondrial contribution to tissue ROS production is probably lower than previously thought. Importantly, in the discussion about the potential role of oxidative stress in mitochondria-dependent aging, ROS generated by inflammation-linked processes and the distribution of free iron also require careful consideration.

  13. Targeting Oxidatively Induced DNA Damage Response in Cancer: Opportunities for Novel Cancer Therapies

    Pierpaola Davalli

    2018-01-01

    Full Text Available Cancer is a death cause in economically developed countries that results growing also in developing countries. Improved outcome through targeted interventions faces the scarce selectivity of the therapies and the development of resistance to them that compromise the therapeutic effects. Genomic instability is a typical cancer hallmark due to DNA damage by genetic mutations, reactive oxygen and nitrogen species, ionizing radiation, and chemotherapeutic agents. DNA lesions can induce and/or support various diseases, including cancer. The DNA damage response (DDR is a crucial signaling-transduction network that promotes cell cycle arrest or cell death to repair DNA lesions. DDR dysregulation favors tumor growth as downregulated or defective DDR generates genomic instability, while upregulated DDR may confer treatment resistance. Redox homeostasis deeply and capillary affects DDR as ROS activate/inhibit proteins and enzymes integral to DDR both in healthy and cancer cells, although by different routes. DDR regulation through modulating ROS homeostasis is under investigation as anticancer opportunity, also in combination with other treatments since ROS affect DDR differently in the patients during cancer development and treatment. Here, we highlight ROS-sensitive proteins whose regulation in oxidatively induced DDR might allow for selective strategies against cancer that are better tailored to the patients.

  14. Scavenging of peroxynitrite by phycocyanin and phycocyanobilin from Spirulina platensis: protection against oxidative damage to DNA.

    Bhat, V B; Madyastha, K M

    2001-07-13

    Peroxynitrite (ONOO(-)) is known to inactivate important cellular targets and also mediate oxidative damage in DNA. The present study has demonstrated that phycocyanin, a biliprotein from spirulina platensis and its chromophore, phycocyanobilin (PCB), efficiently scavenge ONOO(-), a potent physiological inorganic toxin. Scavenging of ONOO(-) by phycocyanin and PCB was established by studying their interaction with ONOO(-) and quantified by using competition kinetics of pyrogallol red bleaching assay. The relative antioxidant ratio and IC(50) value clearly indicate that phycocyanin is a more efficient ONOO(-) scavenger than PCB. The present study has also shown that PCB significantly inhibits the ONOO(-)-mediated single-strand breaks in supercoiled plasmid DNA in a dose-dependent manner with an IC(50) value of 2.9 +/- 0.6 microM. These results suggest that phycocyanin, has the ability to inhibit the ONOO(-)-mediated deleterious biological effects and hence has the potential to be used as a therapeutic agent. Copyright 2001 Academic Press.

  15. Ellipticine induces apoptosis in T-cell lymphoma via oxidative DNA damage

    Savorani, Cecilia; Manfé, Valentina; Biskup, Edyta

    2015-01-01

    (CTCL), a disease that is progressive, chemoresistant and refractory to treatment. We tested the effect of ellipticine in three cell lines with different p53 status: MyLa2000 (p53(wt/wt)), SeAx ((G245S)p53) and Hut-78 ((R196Stop)p53). Ellipticine caused apoptosis in MyLa2000 and SeAx and restored...... the transcriptional activity of (G245S)p53 in SeAx. However, p53 siRNA knockdown experiments revealed that p53 was not required for ellipticine-induced apoptosis in CTCL. The lipophilic antioxidant α-tocopherol inhibited ellipticine-dependent apoptosis and we linked the apoptotic response to the oxidative DNA damage....... Our results provide evidence that ellipticine-induced apoptosis is exerted through DNA damage and does not require p53 activation in T-cell lymphoma....

  16. Characterization of protein interactomes of DNA damages: application to oxidation injuries

    Pietras-Barbier, Ewa

    2013-01-01

    Cyclo-nucleosides are complex DNA damages implying both bases and sugar residues. They are generated by free radicals, in particular by the effect of ionizing radiations, and are not easily covered by cellular mechanisms. Using a protein trapping technique on probes containing these injuries, the negative influence of cyclo-nucleosides on the recognition of its target sequence by a DREF transcription factor and on the interactions of PARP1 with DNA have been identified. Interactions between Fpg bacterial glycosylase and cyclo-nucleosides have been analysed and it has been found that this enzyme has an affinity for them, without excision activity. Finally, a Thermococcus gammatolerans radiation resistant archae has been studied: the formation of simple and complex oxidation injuries at strong radiation doses has been measured and the action mechanism of two new glycosylases has been explained. (author) [fr

  17. Effect of Ventilation Support on Oxidative Stress and Ischemia-Modified Albumin in Neonates.

    Dursun, Arzu; Okumuş, Nurullah; Erol, Sara; Bayrak, Tülin; Zenciroğlu, Ayşegül

    2016-01-01

    Mechanical ventilation (MV) can induce oxidative stress, which plays a critical role in pulmonary injury in intubated neonates. Ischemia-modified albumin (IMA)-a variant of human serum albumin-is a novel biomarker of myocardial ischemia that occurs due to reactive oxygen species during ischemic insult. This study aimed to investigate IMA production due to oxidative stress induced during MV in neonates. This study included 17 neonates that were ventilated using synchronized intermittent mechanical ventilation (SIMV; SIMV group) and 20 neonates ventilated using continuous positive airway pressure (CPAP; CPAP group). Blood samples were collected from each neonate during ventilation support and following cessation of ventilation support. Total antioxidant capacity (TAC) and total oxidant status (TOS) were measured using the Erel method. IMA was measured via an enzyme-linked immunosorbent assay kit (Cusabio Biotech Co., Ltd., Wuhan, China). The oxidant stress index (OSI) was calculated as OSI = TOS/TAC. Statistical analysis was performed using SPSS v.18.0 (SPSS Inc., Chicago, IL) for Windows. Among the neonates included in the study, mean gestational age was 34.7 ± 3.8 weeks, mean birth weight was 2,553 ± 904 g, and 54% were premature. There were not any significant differences in mean gestational age or birth weight between the SIMV and CPAP groups. Among the neonates in both the groups, mean IMA, TOS, and OSI levels were significantly higher during ventilation support (102.2 ± 9.3 IU mL(-1), 15.5 ± 1.3 µmol H2O2 equivalent L(-1), and 0.85 ± 0.22 arbitrary units [ABU], respectively), as compared with following cessation of ventilation support (82.9 ± 11.9 IU mL(-1), 13.4 ± 1.3 µmol H2O2 equivalent L(-1), and 0.64 ± 0.14 ABU, respectively) (p = 0.001). Among all the neonates in the study, mean TAC was significantly lower during ventilation support than the postventilation support (1.82 ± 0.28 mmol 6-hydroxy-2

  18. Oxidative Stress Measures of Lipid and DNA Damage in Human Tears.

    Haworth, Kristina M; Chandler, Heather L

    2017-05-01

    We evaluate feasibility and repeatability of measures for lipid peroxidation and DNA oxidation in human tears, as well as relationships between outcome variables, and compared our findings to previously reported methods of evaluation for ocular sun exposure. A total of 50 volunteers were seen for 2 visits 14 ± 2 days apart. Tear samples were collected from the inferior tear meniscus using a glass microcapillary tube. Oxidative stress biomarkers were quantified using enzyme-linked immunosorbent assay (ELISA): lipid peroxidation by measurement of hexanoyl-lysine (HEL) expression; DNA oxidation by measurement of 8-oxo-2'-deoxyguinosone (8OHdG) expression. Descriptive statistics were generated. Repeatability estimates were made using Bland-Altman plots with mean differences and 95% limits of agreement were calculated. Linear regression was conducted to evaluate relationships between measures. Mean (±SD) values for tear HEL and 8OHdG expression were 17368.02 (±9878.42) nmol/L and 66.13 (±19.99) ng/mL, respectively. Repeatability was found to be acceptable for both HEL and 8OHdG expression. Univariate linear regression supported tear 8OHdG expression and spring season of collection to be predictors of higher tear HEL expression; tear HEL expression was confirmed as a predictor of higher tear 8OHdG expression. We demonstrate feasibility and repeatability of estimating previously unreported tear 8OHdG expression. Seasonal temperature variation and other factors may influence tear lipid peroxidation. Support is demonstrated to suggest lipid damage and DNA damage occur concurrently on the human ocular surface.

  19. Diphenylmethyl selenocyanate attenuates malachite green induced oxidative injury through antioxidation & inhibition of DNA damage in mice

    Das, Jayanta Kumar; Sarkar, Sibani; Hossain, Sk Ugir; Chakraborty, Pramita; Das, Rajat Kumar; Bhattacharya, Sudin

    2013-01-01

    Background & objectives: Malachite green (MG), an environmentally hazardous material, is used as a non permitted food colouring agent, especially in India. Selenium (Se) is an essential nutritional trace element required for animals and humans to guard against oxidative stress induced by xenobiotic compounds of diverse nature. In the present study, the role of the selenium compound diphenylmethyl selenocyanate (DMSE) was assessed on the oxidative stress (OS) induced by a food colouring agent, malachite green (MG) in vivo in mice. Methods: Swiss albino mice (Mus musculus) were intraperitoneally injected with MG at a standardized dose of 100 μg/ mouse for 30 days. DMSE was given orally at an optimum dose of 3 mg/kg b.w. in pre (15 days) and concomitant treatment schedule throughout the experimental period. The parameters viz. ALT, AST, LPO, GSH, GST, SOD, CAT, GPx, TrxR, CA, MN, MI and DNA damage have been evaluated. Results: The DMSE showed its potential to protect against MG induced hepatotoxicity by controlling the serum alanine aminotransferase and aspartate amino transferase (ALT and AST) levels and also ameliorated oxidative stress by modulating hepatic lipid peroxidation and different detoxifying and antioxidative enzymes such as glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), and also the selenoenzymes such as glutathione peroxidase (GPx) and thioredoxin reductase (TrxR) and reduced glutathione level which in turn reduced DNA damage. Interpretation & conclusions: The organo-selenium compound DMSE showed significant protection against MG induced heptotoxicity and DNA damage in murine model. Better protection was observed in pretreatment group than in the concomitant group. Further studies need to be done to understand the mechanism of action. PMID:23852297

  20. Cadmium Chloride Induces DNA Damage and Apoptosis of Human Liver Carcinoma Cells via Oxidative Stress

    Anthony Skipper

    2016-01-01

    Full Text Available Cadmium is a heavy metal that has been shown to cause its toxicity in humans and animals. Many documented studies have shown that cadmium produces various genotoxic effects such as DNA damage and chromosomal aberrations. Ailments such as bone disease, renal damage, and several forms of cancer are attributed to overexposure to cadmium.  Although there have been numerous studies examining the effects of cadmium in animal models and a few case studies involving communities where cadmium contamination has occurred, its molecular mechanisms of action are not fully elucidated. In this research, we hypothesized that oxidative stress plays a key role in cadmium chloride-induced toxicity, DNA damage, and apoptosis of human liver carcinoma (HepG2 cells. To test our hypothesis, cell viability was determined by MTT assay. Lipid hydroperoxide content stress was estimated by lipid peroxidation assay. Genotoxic damage was tested by the means of alkaline single cell gel electrophoresis (Comet assay. Cell apoptosis was measured by flow cytometry assessment (Annexin-V/PI assay. The result of MTT assay indicated that cadmium chloride induces toxicity to HepG2 cells in a concentration-dependent manner, showing a 48 hr-LD50 of 3.6 µg/mL. Data generated from lipid peroxidation assay resulted in a significant (p < 0.05 increase of hydroperoxide production, specifically at the highest concentration tested. Data obtained from the Comet assay indicated that cadmium chloride causes DNA damage in HepG2 cells in a concentration-dependent manner. A strong concentration-response relationship (p < 0.05 was recorded between annexin V positive cells and cadmium chloride exposure. In summary, these in vitro studies provide clear evidence that cadmium chloride induces oxidative stress, DNA damage, and programmed cell death in human liver carcinoma (HepG2 cells.

  1. Amperometric biosensor for hydrogen peroxide based on Hemoglobin/DNA/Poly-2,6-pyridinediamine modified gold electrode

    Tong Zhongqiang; Yuan Ruo; Chai Yaqin; Chen Shihong; Xie Yi

    2007-01-01

    An amperometric biosensor for hydrogen peroxide (H 2 O 2 ) was fabricated based on immobilization of hemoglobin (Hb) on DNA/Poly-2,6-pyridinediamine (PPD) modified Au electrode. PPD thin films were firstly electro-deposited on Au electrode surface which provide a template to attach negatively charged DNA molecules by electrostatic attraction. The adsorbed DNA network provides a good microenvironment for the immobilization of biomolecules and promotes electron transfer between the immobilized Hb and the electrode surface. The fabrication process of the biosensor was characterized by electrochemical impedance spectroscopy. Experimental conditions influencing the biosensor performance such as pH, potential and temperature were assessed and optimized. The proposed biosensor displayed a good electrocatalytic response to the reduction of H 2 O 2 , its linear range is 1.7 μM to 3 mM with a detection limit of 1.0 μM based on the signal-to-noise ratio of 3 (S/N = 3) under the optimized conditions. The Michaelis-Menten constant K m app of Hb immobilized on the electrode surface was found to be 0.8 mM. The biosensor shows high sensitivity and stability. Importantly, this deposition methodology could be further developed for the immobilization of other proteins and biocompounds

  2. Preparation of carboxyl group-modified palladium nanoparticles in an aqueous solution and their conjugation with DNA

    Wang, Zhifei; Li, Hongying; Zhen, Shuang; He, Nongyue

    2012-05-01

    The use of nanomaterials in biomolecular labeling and their corresponding detection has been attracting much attention, recently. There are currently very few studies on palladium nanoparticles (Pd NPs) due to their lack of appropriate surface functionalities for conjugation with DNA. In this paper, we thus firstly present an approach to prepare carboxyl group-modified Pd NPs (with an average size of 6 nm) by the use of 11-mercaptoundecanoic acid (MUDA) as a stabilizer in the aqueous solution. The effect of the various reducing reaction conditions on the morphology of the Pd NPs was investigated. The particles were further characterized by TEM, UV-vis, FT-IR and XPS techniques. DNA was finally covalently conjugated to the surface of the Pd NPs through the activation of the carboxyl group, which was confirmed by agarose gel electrophoresis and fluorescence analysis. The resulting Pd NPs-DNA conjugates show high single base pair mismatch discrimination capabilities. This work therefore sets a good foundation for further applications of Pd NPs in bio-analytical research.

  3. Repair of oxidative DNA base damage in the host genome influences the HIV integration site sequence preference.

    Geoffrey R Bennett

    Full Text Available Host base excision repair (BER proteins that repair oxidative damage enhance HIV infection. These proteins include the oxidative DNA damage glycosylases 8-oxo-guanine DNA glycosylase (OGG1 and mutY homolog (MYH as well as DNA polymerase beta (Polβ. While deletion of oxidative BER genes leads to decreased HIV infection and integration efficiency, the mechanism remains unknown. One hypothesis is that BER proteins repair the DNA gapped integration intermediate. An alternative hypothesis considers that the most common oxidative DNA base damages occur on guanines. The subtle consensus sequence preference at HIV integration sites includes multiple G:C base pairs surrounding the points of joining. These observations suggest a role for oxidative BER during integration targeting at the nucleotide level. We examined the hypothesis that BER repairs a gapped integration intermediate by measuring HIV infection efficiency in Polβ null cell lines complemented with active site point mutants of Polβ. A DNA synthesis defective mutant, but not a 5'dRP lyase mutant, rescued HIV infection efficiency to wild type levels; this suggested Polβ DNA synthesis activity is not necessary while 5'dRP lyase activity is required for efficient HIV infection. An alternate hypothesis that BER events in the host genome influence HIV integration site selection was examined by sequencing integration sites in OGG1 and MYH null cells. In the absence of these 8-oxo-guanine specific glycosylases the chromatin elements of HIV integration site selection remain the same as in wild type cells. However, the HIV integration site sequence preference at G:C base pairs is altered at several positions in OGG1 and MYH null cells. Inefficient HIV infection in the absence of oxidative BER proteins does not appear related to repair of the gapped integration intermediate; instead oxidative damage repair may participate in HIV integration site preference at the sequence level.

  4. Involvement of Werner syndrome protein in MUTYH-mediated repair of oxidative DNA damage

    Kanagaraj, R.; Parasuraman, P.; Mihaljevic, B.; van Loon, B.; Burdová, Kamila; König, C.; Furrer, A.; Bohr, V.A.; Hübscher, U.; Janscak, P.

    2012-01-01

    Roč. 40, č. 17 (2012), s. 8449-8459 ISSN 0305-1048 Grant - others:Swiss National Science Foundation(CH) 31003A-129747/1; Swiss National Science Foundation(CH) 3100-109312/2; Oncosuisse(CH) KLS-02344-02-2009; NIH(US) Z01-AG000726-17 Institutional research plan: CEZ:AV0Z50520514 Institutional support: RVO:68378050 Keywords : DNA repair * oxidative stress * MUTYH * WRN * Pol lambda Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 8.278, year: 2012

  5. A chronic increase of corticosterone age-dependently reduces systemic DNA damage from oxidation in rats

    Jorgensen, Anders; Kalliokoski, Otto; Forsberg, Kristin

    2017-01-01

    Stress and depression are associated with an acceleration of brain and bodily aging; effects which have been attributed to chronic elevations of glucocorticoids. We tested the hypothesis that a three week administration of stress-associated levels of corticosterone (CORT, the principal rodent...... glucocorticoid) would increase systemic and CNS DNA and RNA damage from oxidation; a phenomenon known to be centrally involved in the aging process. We also hypothesized that older individuals would be more sensitive to this effect and that the chronic CORT administration would exacerbate age-related memory...

  6. Heavy Metal-Induced Oxidative DNA Damage in Earthworms: A Review

    Takeshi Hirano

    2010-01-01

    Full Text Available Earthworms can be used as a bio-indicator of metal contamination in soil, Earlier reports claimed the bioaccumulation of heavy metals in earthworm tissues, while the metal-induced mutagenicity reared in contaminated soils for long duration. But we examined the metal-induced mutagenicity in earthworms reared in metal containing culture beddings. In this experiment we observed the generation of 8-oxoguanine (8-oxo-Gua in earthworms exposed to cadmium and nickel in soil. 8-oxo-Gua is a major premutagenic form of oxidative DNA damage that induces GC-to-TA point mutations, leading to carcinogenesis.

  7. Exploring the Role of Genetic Modifiers in DNA Repair and Breast Cancer

    2013-09-01

    organismal sensitivity to the alkylating agent N-methyl-N- nitrosourea . Can- cer Res. 63: 7047–7050. Goytisolo, F. A., E. Samper, J. Martin-Caballero, P...this study refers to this distinction. DNA- alkylating agents (methyl methanesulfonate [MMS], ethylmethanesulfonate [EMS], melphalan, etc.) are of...particular interest at low doses, as this class of genotoxic agents encompasses a number of natural and industrial environmental carcinogens (2). Alkylating

  8. Hydroxyl radicals (·OH) are associated with titanium dioxide (TiO2) nanoparticle-induced cytotoxicity and oxidative DNA damage in fish cells

    Reeves, James F.; Davies, Simon J.; Dodd, Nicholas J.F.; Jha, Awadhesh N.

    2008-01-01

    TiO 2 nanoparticles ( 2 nanoparticles on goldfish skin cells (GFSk-S1), either alone or in combination with UVA. Whilst neutral red retention (NRR) assay (a measure of lysosomal membrane integrity) was used to evaluate cell viability, a modified Comet assay using bacterial lesion-specific repair endonucleases (Endo-III, Fpg) was employed to specifically target oxidative DNA damage. Additionally, electron spin resonance (ESR) studies with different spin traps were carried out for qualitative analysis of free radical generation. For cell viability, TiO 2 alone (0.1-1000 μg ml -1 ) had little effect whereas co-exposure with UVA (0.5-2.0 kJ m -2 ) caused a significant dose-dependent decrease which was dependent on both the concentration of TiO 2 and the dose of UVA administered. For the Comet assay, doses of 1, 10 and 100 μg ml -1 in the absence of UVA caused elevated levels of Fpg-sensitive sites, indicating the oxidation of purine DNA bases (i.e. guanine) by TiO 2 . UVA irradiation of TiO 2 -treated cells caused further increases in DNA damage. ESR studies revealed that the observed toxic effects of nanoparticulate TiO 2 were most likely due to hydroxyl radical (·OH) formation

  9. Electrochemically fabricated polyaniline nanowire-modified electrode for voltammetric detection of DNA hybridization

    Zhu Ningning; Chang Zhu; He Pingang; Fang Yuzhi

    2006-01-01

    A novel and sensitive electrochemical DNA biosensor based on electrochemically fabricated polyaniline nanowire and methylene blue for DNA hybridization detection is presented. Nanowires of conducting polymers were directly synthesized through a three-step electrochemical deposition procedure in an aniline-containing electrolyte solution, by using the glassy carbon electrode (GCE) as the working electrode. The morphology of the polyaniline films was examined using a field emission scanning electron microscope (SEM). The diameters of the nanowires range from 80 to 100 nm. The polyaniline nanowires-coated electrode exhibited very good electrochemical conductivity. Oligonucleotides with phosphate groups at the 5' end were covalently linked onto the amino groups of polyaniline nanowires on the electrode. The hybridization events were monitored with differential pulse voltammetry (DPV) measurement using methylene blue (MB) as an indicator. The approach described here can effectively discriminate complementary from non-complementary DNA sequence, with a detection limit of 1.0 x 10 -12 mol l -1 of complementary target, suggesting that the polyaniline nanowires hold great promises for sensitive electrochemical biosensor applications

  10. Investigation of the induction of oxidative DNA damage by means of an enzyme-linked immunosorbent assay (ELISA) for thymine glycol containing DNA

    Pohlenz-Michel, C.

    1988-01-01