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Sample records for cells chemical cytochrome

  1. Marked and variable inhibition by chemical fixation of cytochrome oxidase and succinate dehydrogenase in single motoneurons

    Science.gov (United States)

    Chalmers, G. R.; Edgerton, V. R.

    1989-01-01

    The effect of tissue fixation on succinate dehydrogenase and cytochrome oxidase activity in single motoneurons of the rat was demonstrated using a computer image processing system. Inhibition of enzyme activity by chemical fixation was variable, with some motoneurons being affected more than others. It was concluded that quantification of enzymatic activity in chemically fixed tissue provides an imprecise estimate of enzyme activities found in fresh-frozen tissues.

  2. Common and uncommon cytochrome P450 reactions related to metabolism and chemical toxicity.

    Science.gov (United States)

    Guengerich, F P

    2001-06-01

    Cytochrome P450 (P450) enzymes catalyze a variety of reactions and convert chemicals to potentially reactive products as well as make compounds less toxic. Most of the P450 reactions are oxidations. The majority of these can be rationalized in the context of an FeO(3+) intermediate and odd electron abstraction/rebound mechanisms; however, other iron-oxygen complexes are possible and alternate chemistries can be considered. Another issue regarding P450-catalyzed reactions is the delineation of rate-limiting steps in the catalytic cycle and the contribution to reaction selectivity. In addition to the rather classical oxidations, P450s also catalyze less generally discussed reactions including reduction, desaturation, ester cleavage, ring expansion, ring formation, aldehyde scission, dehydration, ipso attack, one-electron oxidation, coupling reactions, rearrangement of fatty acid and prostaglandin hydroperoxides, and phospholipase activity. Most of these reactions are rationalized in the context of high-valent iron-oxygen intermediates and Fe(2+) reductions, but others are not and may involve acid-base catalysis. Some of these transformations are involved in the bioactivation and detoxication of xenobiotic chemicals.

  3. The role of cytochrome c on apoptosis induced by Anagrapha falcifera multiple nuclear polyhedrosis virus in insect Spodoptera litura cells.

    Directory of Open Access Journals (Sweden)

    Kaiyu Liu

    Full Text Available There are conflicting reports on the role of cytochrome c during insect apoptosis. Our previous studies have showed that cytochrome c released from the mitochondria was an early event by western blot analysis and caspase-3 activation was closely related to cytochrome c release during apoptosis induced by baculovirus in Spodoptera litura cells (Sl-1 cell line. In the present study, alteration in mitochondrial morphology was observed by transmission electron microscopy, and cytochrome c release from mitochondria in apoptotic Sl-1 cells induced with Anagrapha falcifera multiple nuclear polyhedrosis virus (AfMNPV has further been confirmed by immunofluoresence staining protocol, suggesting that structural disruption of mitochondria and the release of cytochrome c are important events during Lepidoptera insect cell apoptosis. We also used Sl-1 cell-free extract system and the technique of RNA interference to further investigate the role of cytochrome c in apoptotic Sl-1 cells induced by AfMNPV. Caspase-3 activity in cell-free extracts supplemented with exogenous cytochrome c was determined and showed an increase with the extension of incubation time. DsRNA-mediated silencing of cytochrome c resulted in the inhibition of apoptosis and protected the cells from AfMNPV-induced cell death. Silencing of expression of cytochrome c had a remarkable effect on pro-caspase-3 and pro-caspase-9 activation and resulted in the reduction of caspase-3 and caspase-9 activity in Sl-1 cells undergoing apoptosis. Caspase-9 inhibitor could inhibit activation of pro-caspase-3, and the inhibition of the function of Apaf-1 with FSBA blocked apoptosis, hinting that Apaf-1 could be involved in Sl-1 cell apoptosis induced by AfMNPV. Taken together, these results strongly demonstrate that cytochrome c plays an important role in apoptotic signaling pathways in Lepidopteran insect cells.

  4. Cytochrome P450 levels are altered in patients with esophageal squamous-cell carcinoma

    DEFF Research Database (Denmark)

    Bergheim, I.; Wolfgarten, E.; Bollschweiler, E.

    2007-01-01

    AIM: To investigate the role of cytochrome P450 (CYP) in the carcinogenesis of squamous-cell carcinoma (SCC) in human esophagus by determining expression patterns and protein levels of representative CYPs in esophageal tissue of patients with SCC and controls. METHODS: mRNA expression of CYP2E1...

  5. Chemical regulation of abscisic acid catabolism in plants by cytochrome P450 inhibitors.

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    Kitahata, Nobutaka; Saito, Shigeki; Miyazawa, Yutaka; Umezawa, Taishi; Shimada, Yukihisa; Min, Yong Ki; Mizutani, Masaharu; Hirai, Nobuhiro; Shinozaki, Kazuo; Yoshida, Shigeo; Asami, Tadao

    2005-07-15

    Plant hormone abscisic acid (ABA) is an important factor for conferring drought stress resistance on plants. Therefore, small molecules that regulate ABA levels in plants can be useful both for investigating functions of ABA and for developing new plant growth regulators. Abscisic acid (ABA) catabolism in plants is primarily regulated by ABA 8'-hydroxylase, which is a cytochrome P450 (P450). We tested known P450 inhibitors containing a triazole group and found that uniconazole-P inhibited ABA catabolism in cultured tobacco Bright Yellow-2 cells. In a structure-activity study of uniconazole, we found a more effective ABA catabolic inhibitor (diniconazole) than uniconazole-P. Diniconazole, a fungicide, acted as a potent competitive inhibitor of recombinant Arabidopsis ABA 8'-hydroxylase, CYP707A3, in an in vitro assay. Diniconazole-treated plants retained a higher ABA content and higher transcription levels of ABA response genes during rehydration than did untreated plants and were more drought stress tolerant than untreated plants. These results strongly suggest that ABA catabolic inhibitors that target ABA 8'-hydroxylase can regulate the ABA content of plants and conferred drought stress resistance on plants. The optical resolution of diniconazole revealed that the S-form isomer, which is a weak fungicidal isomer, was more active as an ABA catabolic inhibitor than was the R-form isomer.

  6. Involvement of cytochrome c and caspases in apoptotic cell death of human submandibular gland ductal cells induced by concanamycin A.

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    Aiko, Katsuya; Tsujisawa, Toshiyuki; Koseki, Takeyoshi; Hashimoto, Shinichi; Morimoto, Yasuhiro; Amagasa, Teruo; Nishihara, Tatsuji

    2002-08-01

    In the present study, we found that a specific inhibitor of vacuolar type H+-ATPase (V-ATPase), concanamycin A, induced apoptosis in a human submandibular gland ductal cancer cell line, HSG. Immunoblot analysis revealed that cytochrome c was released from mitochondria into the cytoplasm when HSG cells were cultured with concanamycin A for 6 h. The maximum activities of caspase-3 and -9 were reached in HSG cells after 18 and 12 h culture of concanamycin A, respectively. Both caspase-3 and -9 were cleaved to an active form in HSG cells cultured with concanamycin A. Interestingly, concanamycin A decreased the level of heat shock protein 27 (HSP27) in HSG cells. Taken together, these findings suggest that apoptosis in HSG cells induced by concanamycin A is regulated by cytochrome c released from mitochondria into cytoplasm and the subsequent activation of caspases, and that HSP27 may interfere with caspase-dependent apoptotic cell death induced by concanamycin A.

  7. Mitochondrial hyperpolarization and cytochrome-c release in microwave-exposed MCF-7 cells.

    Science.gov (United States)

    Esmekaya, Meric A; Canseven, Ayşe G; Kayhan, Handan; Tuysuz, Mehmet Z; Sirav, Bahriye; Seyhan, Nesrin

    2017-04-01

    This study examines the effects of a 2.1-GHz WCDMA-modulated microwave (MW) radiation on apoptotic activity and mitochondrial membrane potential (ΔΨm) in MCF-7 cells. The cells were exposed to the MW at a specific absorption rate (SAR) of 0.528 W/kg for 4 or 24 h. The antiproliferative effect of MW exposure was determined by the MTT test. Cytochrome-c and p53 levels were determined by an ELISA method. The relative ΔΨm was analysed by JC-1 staining using flow cytometer. Apoptotic rate of the cells was measured by Annexin-V-FITC staining. All assays were performed after certain time of incubations (15 min-4 h) following MW exposure. MW-exposed cells showed a significant decrease in viability when compared to unexposed cells. A significantly larger decrease was observed after longer exposure. The percentage of apoptotic cells, amount of cytochrome-c, and relative ΔΨm were significantly higher in MW-exposed cells. The percent of apoptotic cells and relative ΔΨm in 24 h MW-exposed group was significantly higher than those in 4 h MW-exposed group. However, no significant change was observed in p53 levels. These results demonstrated that exposure to 2.1-GHz WCDMA-modulated MW radiation caused hyperpolarization of mitochondria that in turn induced apoptosis in MCF-7 cells.

  8. Early Decrease in Respiration and Uncoupling Event Independent of Cytochrome c Release in PC12 Cells Undergoing Apoptosis

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    Berghella, Libera; Ferraro, Elisabetta

    2012-01-01

    Cytochrome c is a key molecule in mitochondria-mediated apoptosis. It also plays a pivotal role in cell respiration. The switch between these two functions occurs at the moment of its release from mitochondria. This process is therefore extremely relevant for the fate of the cell. Since cytochrome c mediates respiration, we studied the changes in respiratory chain activity during the early stages of apoptosis in order to contribute to unravel the mechanisms of cytochrome c release. We found that, during staurosporine (STS)- induced apoptosis in PC12 cells, respiration is affected before the release of cytochrome c, as shown by a decrease in the endogenous uncoupled respiration and an uncoupling event, both occurring independently of cytochrome c release. The decline in the uncoupled respiration occurs also upon Bcl-2 overexpression (which inhibits cytochrome c release), while the uncoupling event is inhibited by Bcl-2. We also observed that the first stage of nuclear condensation during STS-induced apoptosis does not depend on the release of cytochrome c into the cytosol and is a reversibile event. These findings may contribute to understand the mechanisms affecting mitochondria during the early stages of apoptosis and priming them for the release of apoptogenic factors. PMID:22666257

  9. Chemical labeling studies on isolated and vesicular bovine heart mitochondrial cytochrome c oxidase

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    Venzke, K.S.; Reynolds, K.A.; Prochaska, L.J.

    1987-05-01

    Bovine heart cytochrome c oxidase dispersed in Triton X-100, Tween 80, or dodecyl maltoside was reacted with the water-soluble reagents (/sup 35/S)-diazonium benzene sulfonate (DABS) (10-100 ..mu..M) or (/sup 125/I)-iodo-DABS (34-55 nM) to map the surface topography of the enzyme in different protein aggregation states. Both reagents gave similar labeling profiles of the enzyme under all conditions. Subunits II, III, and VII were extensively labeled by DABS, while subunits I and VI were unreactive with DABS in each detergent. Subunit V exhibited an increase in DABS labeling when the enzyme was reacted in Tween 80 as compared to the enzyme in Triton X-100 or dodecyl maltoside. Also, components b and c showed an increase in DABS reactivity when the enzyme was modified in dodecyl maltoside. In general, the labeling profile of the enzyme in dodecyl maltoside resembled that of the enzyme in Triton X-100, emphasizing that the mechanism of dispersal of the enzyme by both detergents is similar. Cytochrome c oxidase incorporated into phosphatidylglycerol:phosphatidylcholine(1:20)(w:w) phospholipid vesicles (COV) by cholate dialysis was reacted with DABS and subunits II and III were significantly labeled. Approximately 65-70% of the enzyme in COV was oriented with the cytochrome c binding domain facing the extravesicular medium, as determined by comparison of the DABS labeling in subunit IV in detergent-lysed and intact COV.

  10. [Transfection of eucaryotic cells using cytochrome CYP450 2B6 gene: sensitivity to cyclophosphamide].

    Science.gov (United States)

    Kolomeĭchuk, S N; Abakumova, O Iu; Maslov, M A; Kalashnikova, E A; Morozova, N G; Serebrennikova, G A; Shvets, V I; Sokolov, N N

    2002-01-01

    Sensitivity of 293 human epithelial kidney cells transfected by human cytochrome CYP450 gene to cyclophosphamide was investigated. Transfection was carried out by plasmid DNA containing CYP2B6 gene complexed with cationic liposomes. Liposomes were prepared from mixture of cationic lipids and cholesterol at different molar ratios. Experimental protocol included the following steps: transfection of epithelial kidney cells by complexes of plasmid DNA-cationic liposomes, clone selection in the medium with antibiotic Geneticin G418, selected clone harvesting and their treatment by cyclophosphamide as following cytotoxicity evaluation. It was shown that addition of 0.25 mM of cyclophosphamide resulted in death of 40-45% transfected cell population.

  11. Chemosensitivity of MCF-7 cells to eugenol: release of cytochrome-c and lactate dehydrogenase

    Science.gov (United States)

    Al Wafai, Rana; El-Rabih, Warde; Katerji, Meghri; Safi, Remi; El Sabban, Marwan; El-Rifai, Omar; Usta, Julnar

    2017-01-01

    Phytochemicals have been extensively researched for their potential anticancer effects. In previous study, direct exposure of rat liver mitochondria to eugenol main ingredient of clove, uncoupled mitochondria and increased F0F1ATPase activity. In the present study, we further investigated the effects of eugenol on MCF-7 cells in culture. Eugenol demonstrated: a dose-dependent decrease in viability (MTT assay), and proliferation (real time cell analysis) of MCF-7 cells, (EC50: 0.9 mM); an increase in reactive oxygen species; a decrease in ATP level and mitochondrial membrane potential (MitoPT JC-1 assay); and a release of cytochrome-c and lactate dehydrogenase (Cytotoxicity Detection Kit PLUS) into culture media at eugenol concentration >EC50. Pretreatment with the antioxidants Trolox and N-acetyl cysteine partially restored cell viability and decreased ROS, with Trolox being more potent. Expression levels of both anti- and pro-apoptotic markers (Bcl-2 and Bax, respectively) decreased with increasing eugenol concentration, with no variation in their relative ratios. Eugenol-treated MCF-7 cells overexpressing Bcl-2 exhibited results similar to those of MCF-7. Our findings indicate that eugenol toxicity is non-apoptotic Bcl-2 independent, affecting mitochondrial function and plasma membrane integrity with no effect on migration or invasion. We report here the chemo-sensitivity of MCF-7 cells to eugenol, a phytochemical with anticancer potential. PMID:28272477

  12. Glucose metabolism determines resistance of cancer cells to bioenergetic crisis after cytochrome-c release.

    LENUS (Irish Health Repository)

    Huber, Heinrich J

    2011-03-01

    Many anticancer drugs activate caspases via the mitochondrial apoptosis pathway. Activation of this pathway triggers a concomitant bioenergetic crisis caused by the release of cytochrome-c (cyt-c). Cancer cells are able to evade these processes by altering metabolic and caspase activation pathways. In this study, we provide the first integrated system study of mitochondrial bioenergetics and apoptosis signalling and examine the role of mitochondrial cyt-c release in these events. In accordance with single-cell experiments, our model showed that loss of cyt-c decreased mitochondrial respiration by 95% and depolarised mitochondrial membrane potential ΔΨ(m) from -142 to -88 mV, with active caspase-3 potentiating this decrease. ATP synthase was reversed under such conditions, consuming ATP and stabilising ΔΨ(m). However, the direction and level of ATP synthase activity showed significant heterogeneity in individual cancer cells, which the model explained by variations in (i) accessible cyt-c after release and (ii) the cell\\'s glycolytic capacity. Our results provide a quantitative and mechanistic explanation for the protective role of enhanced glucose utilisation for cancer cells to avert the otherwise lethal bioenergetic crisis associated with apoptosis initiation.

  13. Melatonin Protects Cultured Tobacco Cells against Lead-Induced Cell Death via Inhibition of Cytochrome c Translocation

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    Agnieszka Kobylińska

    2017-09-01

    Full Text Available Melatonin was discovered in plants more than two decades ago and, especially in the last decade, it has captured the interests of plant biologists. Beyond its possible participation in photoperiod processes and its role as a direct free radical scavenger as well as an indirect antioxidant, melatonin is also involved in plant defense strategies/reactions. However, the mechanisms that this indoleamine activates to improve plant stress tolerance still require identification and clarification. In the present report, the ability of exogenous melatonin to protect Nicotiana tabacum L. line Bright Yellow 2 (BY-2 suspension cells against the toxic exposure to lead was examined. Studies related to cell proliferation and viability, DNA fragmentation, possible translocation of cytochrome c from mitochondria to cytosol, cell morphology after fluorescence staining and also the in situ accumulation of superoxide radicals measured via the nitro blue tetrazolium reducing test, were conducted. This work establishes a novel finding by correcting the inhibition of release of mitochondrial ctytocrome c in to the cytoplasm with the high accumulation of superoxide radicals. The results show that pretreatment with 200 nm of melatonin protected tobacco cells from DNA damage caused by lead. Melatonin, as an efficacious antioxidant, limited superoxide radical accumulation as well as cytochrome c release thereby, it likely prevents the activation of the cascade of processes leading to cell death. Fluorescence staining with acridine orange and ethidium bromide documented that lead-stressed cells additionally treated with melatonin displayed intact nuclei. The results revealed that melatonin at proper dosage could significantly increase BY-2 cell proliferation and protected them against death. It was proved that melatonin could function as an effective priming agent to promote survival of tobacco cells under harmful lead-induced stress conditions.

  14. Expression of recombinant Pseudomonas stutzeri di-heme cytochrome c(4) by high-cell-density fed-batch cultivation of Pseudomonas putida

    DEFF Research Database (Denmark)

    Thuesen, Marianne Hallberg; Nørgaard, Allan; Hansen, Anne Merete

    2003-01-01

    The gene of the di-heme protein cytochrome c(4) from Pseudomonas stutzeri was expressed in Pseudomonas putida. High-yield expression of the protein was achieved by high-cell-density fed-batch cultivation using an exponential glucose feeding strategy. The recombinant cytochrome c(4) protein...

  15. Cytochromes P450 are Expressed in Proliferating Cells in Barrett's Metaplasia

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    Steven J. Hughes

    1999-06-01

    Full Text Available The expression of cytochromes P450 (CYP in Barrett's esophagus and esophageal squamous mucosa was investigated. Esophagectomy specimens from 23 patients were examined for CYP expression of CYP1A2, CYP3A4, CYP2C9/10, and CYP2E1 by immunohistochemical analysis, and the expression of CYP1A1, CYP3A4, CYP1B1, CYP2E1, and CYP2C9/10 in these tissues was further confirmed by reverse transcription polymerase chain reaction. Immunohistochemical analysis of esophageal squamous mucosa (n = 12 showed expression of CYP1A2, CYP3A4, CYP2E1, and CYP2C9/10 proteins, but it was noted that cells within the basal proliferative zone did not express CYPs. Immunohistochemical analysis of Barrett's esophagus (n = 13 showed expression of CYP1A2, CYP3A4, CYP2E1, and CYP2C9/10 that was prominent in the basal glandular regions, which are areas containing a high percentage of actively proliferating cells. Immunohistochemical staining for both proliferating cell nuclear antigen and the CYPs further supported the colocalization of CYP expression to areas of active cell proliferation in Barrett's esophagus, whereas in the esophageal squamous epithelium, CYP expression is limited to cells that are not proliferating. RT-PCR with amplification product sequence analysis confirmed CYP1A1, CYP3A4, CYP1B1, CYP2E1, and CYP2C9/10 mRNA expression in Barrett's esophagus. These data suggest that the potential ability of cells in Barrett's esophagus to both activate carcinogens and proliferate may be important risk factors affecting carcinogenesis in this metaplastic tissue.

  16. Low-intensity laser irradiation at 660 nm stimulates cytochrome c oxidase in stressed fibroblast cells.

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    Houreld, Nicolette N; Masha, Roland T; Abrahamse, Heidi

    2012-07-01

    Low-intensity laser irradiation (LILI) has been used to modulate a variety of biological processes, including diabetic wound healing. The mechanism of action is thought to exist primarily with the mitochondria. This study aimed to determine the effect of irradiation on normal, diabetic, and ischemic mitochondrial electron transport chain (ETC) complexes. Normal, diabetic and ischemic human skin fibroblast mitochondria were irradiated in vitro at a wavelength of 660 nm and a fluence of either 5 or 15 J/cm(2). Non-irradiated mitochondria served as controls. Enzyme activities of mitochondrial complexes I, II, III, and IV were determined immediately post-irradiation. Normal, diabetic, and ischemic cells were irradiated and adenosine triphosphate (ATP) and active mitochondria were determined by luminescence and fluorescent microscopy, respectively. Irradiated diabetic mitochondria at a fluence of 15 J/cm(2) showed a significant decrease in complex III activity (P < 0.05). Normal (P < 0.01) and diabetic (P < 0.05) mitochondria irradiated at either 5 or 15 J/cm(2) showed a significant increase in complex IV activity. ATP results showed a significant increase in irradiated normal cells (5 J/cm(2); P < 0.05) and diabetic cells (15 J/cm(2); P < 0.01). There was a higher accumulation of active mitochondria in irradiated cells than non-irradiated cells. Irradiation at 660 nm has the ability to influence mitochondrial enzyme activity, in particular cytochrome c oxidase. This leads to increased mitochondrial activity and ATP synthesis. Copyright © 2012 Wiley Periodicals, Inc.

  17. Immunohistochemical analysis of cytochrome C oxidase facilitates differentiation between oncocytoma and chromophobe renal cell carcinoma.

    Science.gov (United States)

    Adam, Alexander C; Scriba, Alexander; Ortmann, Monika; Huss, Sebastian; Kahl, Philip; Steiner, Susanne; Störkel, Stephan; Büttner, Reinhard

    2015-01-01

    In this study, immunohistochemical staining pattern of cytochrome c oxidase subunit 1 (CCO1) was investigated in the differentiation of renal oncocytoma (RO) from eosinophilic (EoC) and classic chromophobe renal cell carcinoma (ChRCC). A feature found in ChRCC/EoC but not in RO is the predominance of a perinuclear halo when stained for CCO1. In a cohort of 103 mixed cases including 44 RO, 37 classic ChRCC and 22 EoC, the diagnosis based on this immunohistochemical feature alone was consistent with the previous routine diagnosis in 95.7%. We reached 100% specificity and 81.4% sensitivity of this pattern in ChRCC. Specificity for RO was 93.2% and sensitivity correspondingly 95.5%. We propose a novel and easily interpretable immunohistochemical method for the discrimination of benign RO from certain subtypes of malignant ChRCC. Because of strong similarity in morphology of the 2 entities the diagnosis often cannot be made based on standard histopathology alone. The study describes for the first time the formation of a perinuclear halo in CCO1 immunohistochemistry as a highly specific marker for the diagnosis of ChRCC. We think this method can be a strong amendment for routine diagnostics in renal cell carcinoma.

  18. Effect of Flavonoids on Glutathione Level, Lipid Peroxidation and Cytochrome P450 CYP1A1 Expression in Human Laryngeal Carcinoma Cell Lines

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    Lidija Vuković

    2007-01-01

    Full Text Available Flavonoids are phytochemicals exhibiting a wide range of biological activities, among which are antioxidant activity, the ability to modulate activity of several enzymes or cell receptors and possibility to interfere with essential biochemical pathways. Using human laryngeal carcinoma HEp2 cells and their drug-resistant CK2 subline, we examined the effect of five flavonoids, three structurally related flavons (quercetin, fisetin, and myricetin, one flavonol (luteolin and one glycosilated flavanone (naringin for: (i their ability to inhibit mitochondrial dehydrogenases as an indicator of cytotoxic effect, (ii their influence on glutathione level, (iii antioxidant/prooxidant effects and influence on cell membrane permeability, and (iv effect on expression of cytochrome CYP1A1. Cytotoxic action of the investigated flavonoids after 72 hours of treatment follows this order: luteolin>quercetin>fisetin>naringin>myricetin. Our results show that CK2 were more resistant to toxic concentrations of flavonoids as compared to parental cells. Quercetin increased the total GSH level in both cell lines. CK2 cells are less perceptible to lipid peroxidation and damage caused by free radicals. Quercetin showed prooxidant effect in both cell lines, luteolin only in HEp2 cells, whereas other tested flavonoids did not cause lipid peroxidation in the tested cell lines. These data suggest that the same compound, quercetin, can act as a prooxidant, but also, it may prevent damage in cells caused by free radicals, due to the induction of GSH, by forming less harmful complex. Quercetin treatment damaged cell membranes in both cell lines. Fisetin caused higher cell membrane permeability only in HEp2 cells. However, these two compounds did not enhance the damage caused by hydrogen peroxide. Quercetin, naringin, myricetin and fisetin increased the expression of CYP1A1 in both cell lines, while luteolin decreased basal level of CYP1A1 only in HEp2 cells. In conclusion, small

  19. Suicidal gene therapy with rabbit cytochrome P450 4B1/4-ipomeanol, 2-aminoanthracene system in glioma cell

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Su Jin; Kang, Joo Hyun; Kim, Kwang Il; Lee, Tae Sup; Lee, Yong Jin; Woo, Kwang Sun; Chung, Wee Sup; Cheon, Gi Jeong; Choi, Chang Woon; Lim, Sang Moo [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)

    2010-10-15

    Suicidal gene therapy is based on the transduction of tumor cells with 'suicide' genes encoding for prodrugactivating enzymes that render target cells susceptible to prodrug treatment. Suicidal gene therapy results in the death of tumor with the expression of gene encoding enzyme that converts non-toxic prodrug into cytotoxic product. Cytochrome P450 4B1 (CYP4B1) activates 4- ipomeanol (4-ipo) and 2-aminoanthracene (2-AA) to cytotoxic furane epoxide and unsaturated dialdehyde intermediate. In this study, therapeutic effects of suicidal gene therapy with rabbit CYP4B1/4-ipo or CYP4B1/2-AA system

  20. MicroRNA-661 Enhances TRAIL or STS Induced Osteosarcoma Cell Apoptosis by Modulating the Expression of Cytochrome c1

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    Lin Fan

    2017-04-01

    Full Text Available Aim: Osteosarcoma (OS is an aggressive bone malignancy that affects rapidly growing bones and is associated with a poor prognosis. Our previous study showed that cytochrome c1 (CYC1, a subunit of the cytochrome bc1 complex (complex III of the mitochondrial electron chain, is overexpressed in human OS tissues and cell lines and its silencing induces apoptosis in vitro and inhibits tumor growth in vivo. Here, we investigated the mechanism underlying the modulation of CYC1 expression in OS and its role in the resistance of OS to apoptosis. Methods: qRT-PCR, luciferase reporter assay, western blotting, fow cytometry, and animal experiments were performed in this study. Results: MicroRNA (miR-661 was identified as a downregulated miRNA in OS tissues and cells and shown to directly target CYC1. Ectopically expressed miR-661 inhibited OS cell growth, promoted apoptosis, and reduced the activity of mitochondrial complex III. miR-661 overexpression enhanced TRAIL or STS induced apoptosis and promoted the release of cytochrome c into the cytosol, which induced caspase-9 activation, and these effects were abolished by a caspase-3 inhibitor. Overexpression of CYC1 rescued the effects of miR-661 on sensitizing OS cells to TRAIL or STS induced apoptosis, indicating that the antitumor effect of miR-661 is mediated by the downregulation of CYC1. In vivo, miR-661 overexpression sensitized tumors to TRAIL or STS induced apoptosis in a xenograft mouse model, and these effects were attenuated by co-expression of CYC1. Conclusion: Taken together, our results indicate that miR-661 plays a tumor suppressor role in OS mediated by the downregulation of CYC1, suggesting a potential mechanism underlying cell death resistance in OS.

  1. The cytotoxic macrolide FD-891 induces caspase-8-dependent mitochondrial release of cytochrome c and subsequent apoptosis in human leukemia Jurkat cells.

    Science.gov (United States)

    Inaba, Susumu; Eguchi, Tadashi; Motegi, Atsushi; Mizoue, Kazutoshi; Usui, Takeo; Nagai, Kazuo; Kataoka, Takao

    2009-09-01

    The 16-membered macrolide FD-891 exerts cytotoxicity toward several cancer cell lines. In this study, we showed that FD-891 induces apoptosis in various human cancer cell lines. Human leukemia Jurkat cells were highly sensitive to FD-891, exhibiting caspase activation and mitochondrial release of cytochrome c into the cytosol at early time points after exposure to FD-891. By contrast, Jurkat cells deficient in caspase-8 were resistant to FD-891-induced apoptosis and manifested little induction of cytochrome c release as well as caspase-9 processing. Consistent with these results, the overexpression of the Bcl-2 family member Bcl-x(L) or the caspase-8 modulator c-FLIP(L) markedly prevented FD-891-induced apoptosis. These results clearly demonstrate that FD-891 triggers caspase-8-dependent mitochondrial release of cytochrome c and subsequent apoptosis in Jurkat cells.

  2. Metallothionein 2A affects the cell respiration by suppressing the expression of mitochondrial protein cytochrome c oxidase subunit II.

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    Bragina, Olga; Gurjanova, Karina; Krishtal, Jekaterina; Kulp, Maria; Karro, Niina; Tõugu, Vello; Palumaa, Peep

    2015-06-01

    Metallothioneins (MT) are involved in a broad range of cellular processes and play a major role in protection of cells towards various stressors. Two functions of MTs, namely the maintaining of the homeostasis of transition metal ions and the redox balance, are directly linked to the functioning of mitochondria. Dyshomeostasis of MTs is often related with malfunctioning of mitochondria; however, the mechanism by which MTs affect the mitochondrial respiratory chain is still unknown. We demonstrated that overexpression of MT-2A in HEK cell line decreased the oxidative phosphorylation capacity of the cells. HEK cells overexpressing MT-2A demonstrated reduced oxygen consumption and lower cellular ATP levels. MT-2A did not affect the number of mitochondria, but reduced specifically the level of cytochrome c oxidase subunit II protein, which resulted in lower activity of the complex IV.

  3. Structure-Function, Stability, and Chemical Modification of the Cyanobacterial Cytochrome b6f Complex from Nostoc sp. PCC 7120*

    Science.gov (United States)

    Baniulis, Danas; Yamashita, Eiki; Whitelegge, Julian P.; Zatsman, Anna I.; Hendrich, Michael P.; Hasan, S. Saif; Ryan, Christopher M.; Cramer, William A.

    2009-01-01

    The crystal structure of the cyanobacterial cytochrome b6f complex has previously been solved to 3.0-Å resolution using the thermophilic Mastigocladus laminosus whose genome has not been sequenced. Several unicellular cyanobacteria, whose genomes have been sequenced and are tractable for mutagenesis, do not yield b6f complex in an intact dimeric state with significant electron transport activity. The genome of Nostoc sp. PCC 7120 has been sequenced and is closer phylogenetically to M. laminosus than are unicellular cyanobacteria. The amino acid sequences of the large core subunits and four small peripheral subunits of Nostoc are 88 and 80% identical to those in the M. laminosus b6f complex. Purified b6f complex from Nostoc has a stable dimeric structure, eight subunits with masses similar to those of M. laminosus, and comparable electron transport activity. The crystal structure of the native b6f complex, determined to a resolution of 3.0Å (PDB id: 2ZT9), is almost identical to that of M. laminosus. Two unique aspects of the Nostoc complex are: (i) a dominant conformation of heme bp that is rotated 180° about the α- and γ-meso carbon axis relative to the orientation in the M. laminosus complex and (ii) acetylation of the Rieske iron-sulfur protein (PetC) at the N terminus, a post-translational modification unprecedented in cyanobacterial membrane and electron transport proteins, and in polypeptides of cytochrome bc complexes from any source. The high spin electronic character of the unique heme cn is similar to that previously found in the b6f complex from other sources. PMID:19189962

  4. Effect of bixin and norbixin on the expression of cytochrome P450 in HepG2 cell line.

    Science.gov (United States)

    Matuo, Míriam Cristina Sakuragui; de Oliveira Takamoto, Rafael Teruiti; Kikuchi, Irene Satiko; de Jesus Andreoli Pinto, Terezinha

    2013-08-01

    Bixin and norbixin are the main components of annatto, which is extracted from Bixa orellana and largely used as natural colorant in the food and pharmaceutical industries. Annatto can enhance CYP1A and CYP2B activity in rats; however, the inducer effect has not been investigated in human cell lines. In this study, the ability of bixin and norbixin to induce the cytochrome P450 (CYP) enzymes was assessed in HepG2 human hepatoma cell line. HepG2 cells were treated with bixin and norbixin, and the expression of the CYP genes quantified by real-time reverse transcription polymerase chain reaction (RT-PCR). Expression of CYP1A1 and CYP1A2 was significantly increased by bixin treatment, while CYP2B6, 2C9, 2E1 and 3A4 were unaffected. Cells were treated with norbixin showed no inducer effect. The results suggest that the inducer potential of annatto is attributed to bixin, but not to norbixin, despite their similarities in molecular structure. © 2013 International Federation for Cell Biology.

  5. Inhibition of tolbutamide 4-methylhydroxylation by a series of non-steroidal anti-inflammatory drugs in V79-NH cells expressing human cytochrome P4502C10

    NARCIS (Netherlands)

    Kappers, W.A.; Groene, E.M. de; Kleij, L.A.; Witkamp, R.F.; Zweers-Zeilmaker, W.M.; Feron, V.J.; Horbach, G.J.

    1996-01-01

    1. To study the role of cytochrome P4502C10 in the metabolism of the non-steroidal antiinflammatory drugs (NSAIDs) diclofenac, phenylbutazone, fenoprofen, ibuprofen, flurbiprofen, ketoprofen and naproxen, a cell line was developed stably expressing CYP2C10 cDNA. A retroviral vector construct,

  6. Laboratory Prototype of Bioreactor for Oxidation of Toxic D-Lactate Using Yeast Cells Overproducing D-Lactate Cytochrome c Oxidoreductase

    Directory of Open Access Journals (Sweden)

    Maria Karkovska

    2016-01-01

    Full Text Available D-lactate is a natural component of many fermented foods like yogurts, sour milk, cheeses, and pickles vegetable products. D-lactate in high concentrations is toxic for children and people with short bowel syndrome and provokes encephalopathy. These facts convincingly demonstrate a need for effective tools for the D-lactate removal from some food products. The main idea of investigation is focused on application of recombinant thermotolerant methylotrophic yeast Hansenula polymorpha “tr6,” overproducing D-lactate: cytochrome c oxidoreductase (EC 1.1.2.4, D-lactate cytochrome c oxidoreductase, D-lactate dehydrogenase (cytochrome, DLDH. In addition to 6-fold overexpression of DLDH under a strong constitutive promoter (prAOX, the strain of H. polymorpha “tr6” (gcr1 catX/Δcyb2, prAOX_DLDH is characterized by impairment in glucose repression of AOX promoter, devoid of catalase and L-lactate-cytochrome c oxidoreductase activities. Overexpression of DLDH coupling with the deletion of L-lactate-cytochrome c oxidoreductase activity opens possibility for usage of the strain as a base for construction of bioreactor for removing D-lactate from fermented products due to oxidation to nontoxic pyruvate. A laboratory prototype of column-type bioreactor for removing a toxic D-lactate from model solution based on permeabilized cells of the H. polymorpha “tr6” and alginate gel was constructed and efficiency of this process was tested.

  7. A novel cytochrome P450 gene from Catharanthus roseus cell line C20hi: cloning and characterization of expression

    Directory of Open Access Journals (Sweden)

    Lihong He

    2012-06-01

    Full Text Available An expressed sequence tag (EST obtained from a subtractive-suppression hybridization cDNA library constructed using Catharanthus roseus cell line C20hi and its parental cell line C20D was used to clone a full-length cytochrome P450 cDNA of cyp71d1. The encoded polypeptide contained 507 amino acids with 39–56% identity to other CYP71D subfamily members at the amino acid level. Expression characteristics of cyp71d1 were determined using semi-quantitative RT-PCR. The cyp71d1 transcript was expressed in all three cell lines with the highest level in the cell line C20hi. In the mature C. roseus plant, the cyp71d1 cDNA was highly expressed in petals, roots and stems, but very weakly expressed in young leaves. Its transcription level increased with the development of flowers. 2,4-D could down-regulate the transcription of cyp71d1, as did KT, but only to a minor degree. Neither light nor yeast elicitor could induce the transcription of cyp71d1.

  8. A kinetic study of the oxidation by molecular oxygen of the cytochrome chain of intact yeast cells, Acetobacter suboxydans cells, and of particulate suspensions of heart muscle.

    Science.gov (United States)

    Ludwig, G D; Kuby, S A; Edelman, G M; Chance, B

    1983-01-01

    The pre-steady state kinetics of the cytochrome c oxidase reaction with oxygen were studied by a variation in the reaction time between approximately 6 and 25 ms at oxygen concentrations less than 6 mumol/l. For baker's yeast, a pseudo-first-order velocity constant of approximately 150 s-1 at 1.3 mumol/l O2 was obtained corresponding to a second-order reaction between O2 and a3 at a forward velocity constant (k+1) of approximately 3 X 10(7) liter equiv.-1s-1. Thus, the membrane-bound oxidase in the intact cell exhibits one of the most rapid enzyme-substrate reactions to be reported. The value is identical with that of Greenwood and Gibson on an isolated, solubilized cytochrome c oxidase. Similar values of k+1 are calculated from the turnover numbers [k+2 (a+2)] divided by the Km values (formula; see text) measured for these yeast preparations, which points to an almost negligible reverse reaction (k-1) compared to k+2(a+2). Similar calculations for the membrane-bound cytochrome c oxidase of heart muscle give a value of k+1 approximately equal to 10(7) liter equiv.-1s-1. The concordance of the different values of k+1 supports the view that the yeast cell wall does not impart a significant diffusion barrier to the transport of molecular oxygen. In contrast, Acetobacter suboxydans exhibits a much larger value for Km, and has a terminal oxidase of different kinetic parameters.

  9. Effects of extremely low frequency electromagnetic field (ELF-EMF) on catalase, cytochrome P450 and nitric oxide synthase in erythro-leukemic cells.

    Science.gov (United States)

    Patruno, Antonia; Tabrez, Shams; Pesce, Mirko; Shakil, Shazi; Kamal, Mohammad A; Reale, Marcella

    2015-01-15

    Extremely low frequency electromagnetic fields (ELF-EMFs) are widely employed in electrical appliances and different equipment such as television sets, mobile phones, computers and microwaves. The molecular mechanism through which ELF-EMFs can influence cellular behavior is still unclear. A hypothesis is that ELF-EMFs could interfere with chemical reactions involving free radical production. Under physiologic conditions, cells maintain redox balance through production of ROS/RNS and antioxidant molecules. The altered balance between ROS generation and elimination plays a critical role in a variety of pathologic conditions including neurodegenerative diseases, aging and cancer. Actually, there is a disagreement as to whether there is a causal or coincidental relationship between ELF-EMF exposure and leukemia development. Increased ROS levels have been observed in several hematopoietic malignancies including acute and chronic myeloid leukemias. In our study, the effect of ELF-EMF exposure on catalase, cytochrome P450 and inducible nitric oxide synthase activity and their expression by Western blot analysis in myelogenous leukemia cell line K562 was evaluated. A significant modulation of iNOS, CAT and Cyt P450 protein expression was recorded as a result of ELF-EMF exposure in both phorbol 12-myristate 13-acetate (PMA)-stimulated and non-stimulated cell lines. Modulation in kinetic parameters of CAT, CYP-450 and iNOS enzymes in response to ELF-EMF indicates an interaction between the ELF-EMF and the enzymological system. These new insights might be important in establishing a mechanistic framework at the molecular level within which the possible effects of ELF-EMF on health can be understood. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Fuel cells for chemicals and energy cogeneration

    Energy Technology Data Exchange (ETDEWEB)

    Alcaide, Francisco; Cabot, Pere-Lluis; Brillas, Enric [Laboratori de Ciencia i Tecnologia Electroquimica de Materials (LCTEM), Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain)

    2006-01-23

    Fuel cells (FCs) are mainly applied for electricity generation. This paper presents a review of specific FCs with ability to produce useful chemicals at the same time. The chemical cogeneration processes have been classified according to the different types of fuel cells. Thus, it is shown that a flow alkaline FC (AFC) is able to produce hydrogen peroxide. In aqueous acid or neutral FCs, hydrogenations, dehydrogenations, halogenations and oxidations, together with pollution abatement solutions, are reported. Hydrogen peroxide and valuable organic chemicals can also be obtained from polymer electrolyte FCs (PEFCs). A phosphoric acid FC (PAFC) allows the selective oxidation of hydrocarbons and aromatic compounds, and the production of industrial compounds such as cresols. Molten salt FCs (similar to molten carbonate or MCFCs) can be applied to obtain acetaldehyde with high product selectivity from ethanol oxidation at the anode. Solid oxide FCs (SOFCs) are able of chemical cogeneration of valuable industrial inorganic compounds such as nitric oxide with high yields. Although the number of related papers in the literature is small, the potential economic interest of this emergent field, related to the recent commercial development of fuel cells, is demonstrated in some cases, and the corresponding results encourage the development of FCs with electrocogeneration of useful chemicals with high added value and electricity. (author)

  11. CYP94A1, a plant cytochrome P450-catalyzing fatty acid omega-hydroxylase, is selectively induced by chemical stress in Vicia sativa seedlings.

    Science.gov (United States)

    Benveniste, Irène; Bronner, Roberte; Wang, Yong; Compagnon, Vincent; Michler, Pierre; Schreiber, Lukas; Salaün, Jean-Pierre; Durst, Francis; Pinot, Franck

    2005-08-01

    CYP94A1 is a cytochrome P450 (P450) catalyzing fatty acid (FA) omega-hydroxylation in Vicia sativa seedlings. To study the physiological role of this FA monooxygenase, we report here on its regulation at the transcriptional level (Northern blot). Transcripts of CYP94A1, as those of two other P450-dependent FA hydroxylases (CYP94A2 and CYP94A3) from V. sativa, are barely detectable during the early development of the seedlings. CYP94A1 transcripts, in contrast to those of the two other isoforms, are rapidly (less than 20 min) and strongly (more than 100 times) enhanced after treatment by clofibrate, an hypolipidemic drug in animals and an antiauxin (p-chlorophenoxyisobutyric acid) in plants, by auxins (2,4-dichlorophenoxyacetic acid and indole-3-acetic acid), by an inactive auxin analog (2,3-dichlorophenoxyacetic acid), and also by salicylic acid. All these compounds activate CYP94A1 transcription only at high concentrations (50-500 microM range). In parallel, these high levels of clofibrate and auxins modify seedling growth and development. Therefore, the expression of CYP94A1 under these conditions and the concomitant morphological and cytological modifications would suggest the implication of this P450 in a process of plant defense against chemical injury.

  12. Guard Cell and Tropomyosin Inspired Chemical Sensor

    Directory of Open Access Journals (Sweden)

    Jacquelyn K.S. Nagel

    2013-10-01

    Full Text Available Sensors are an integral part of many engineered products and systems. Biological inspiration has the potential to improve current sensor designs as well as inspire innovative ones. This paper presents the design of an innovative, biologically-inspired chemical sensor that performs “up-front” processing through mechanical means. Inspiration from the physiology (function of the guard cell coupled with the morphology (form and physiology of tropomyosin resulted in two concept variants for the chemical sensor. Applications of the sensor design include environmental monitoring of harmful gases, and a non-invasive approach to detect illnesses including diabetes, liver disease, and cancer on the breath.

  13. Structure Guided Chemical Modifications of Propylthiouracil Reveal Novel Small Molecule Inhibitors of Cytochrome b5 Reductase 3 That Increase Nitric Oxide Bioavailability.

    Science.gov (United States)

    Rahaman, Md Mizanur; Reinders, Fabio G; Koes, David; Nguyen, Anh T; Mutchler, Stephanie M; Sparacino-Watkins, Courtney; Alvarez, Roger A; Miller, Megan P; Cheng, Dongmei; Chen, Bill B; Jackson, Edwin K; Camacho, Carlos J; Straub, Adam C

    2015-07-03

    NADH cytochrome b5 reductase 3 (CYB5R3) is critical for reductive reactions such as fatty acid elongation, cholesterol biosynthesis, drug metabolism, and methemoglobin reduction. Although the physiological and metabolic importance of CYB5R3 has been established in hepatocytes and erythrocytes, emerging investigations suggest that CYB5R3 is critical for nitric oxide signaling and vascular function. However, advancement toward fully understanding CYB5R3 function has been limited due to a lack of potent small molecule inhibitors. Because of this restriction, we modeled the binding mode of propylthiouracil, a weak inhibitor of CYB5R3 (IC50 = ∼275 μM), and used it as a guide to predict thiouracil-biased inhibitors from the set of commercially available compounds in the ZINC database. Using this approach, we validated two new potent derivatives of propylthiouracil, ZINC05626394 (IC50 = 10.81 μM) and ZINC39395747 (IC50 = 9.14 μM), both of which inhibit CYB5R3 activity in cultured cells. Moreover, we found that ZINC39395747 significantly increased NO bioavailability in renal vascular cells, augmented renal blood flow, and decreased systemic blood pressure in response to vasoconstrictors in spontaneously hypertensive rats. These compounds will serve as a new tool to examine the biological functions of CYB5R3 in physiology and disease and also as a platform for new drug development. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  14. Realgar-induced apoptosis of cervical cancer cell line Siha via cytochrome c release and caspase-3 and caspase-9 activation.

    Science.gov (United States)

    Cheng, Yan-xiang; Liu, Rong; Wang, Qin; Li, Bing-shu; Xu, Xue-xian; Hu, Min; Chen, Lu; Fu, Qiong; Pu, De-min; Hong, Li

    2012-05-01

    To explore the molecular mechanism of realgar-induced apoptosis of cervical cancer cells. The cervical cancer cell line Siha was used to determine the cell viability and apoptosis after treatment with realgar using MTT assay and flow cytometry. The activities of caspase-3, -8, and -9 were detected by fluorescence resonance energy transfer technology and colorimetric assay, while the levels of Bcl-2, cytochrome c, and Bax were detected by Western blot method. Induction of apoptosis by realgar was detected in Siha cell line in a dose-dependent manner. The apoptosis was accompanied by a significant increase in cytochrome c release and activation of caspase-3 and caspase-9 but not caspase-8. Further, the realgar-induced apoptosis was inhibited by a broad-spectrum caspase inhibitor, a caspase-3 inhibitor, and a caspase-9 inhibitor but not by a caspase-8 inhibitor. Bcl-2 and Bax protein expressions were not changed by realgar. The induction of apoptosis by realgar is mediated through a cytochrome c-dependent pathway, which sequentially activates caspase-9 and caspase-3.

  15. Selective suicide of cross-presenting CD8+ dendritic cells by cytochrome c injection shows functional heterogeneity within this subset.

    Science.gov (United States)

    Lin, Ming Lee; Zhan, Yifan; Proietto, Anna I; Prato, Sandro; Wu, Li; Heath, William R; Villadangos, Jose A; Lew, Andrew M

    2008-02-26

    Cross-presentation as a fundamental pathway of activating CD8(+) T cells has been well established. So far the application of this concept in vivo is limited, and the mechanisms that specialize CD8(+) dendritic cells (DCs) for this task are not fully understood. Here we take advantage of the specific cytosolic export feature of cross-presenting DCs together with the property of cytosolic cytochrome c (cyt c) in initiating Apaf-1-dependent apoptosis selectively in cross-presenting DCs. A single i.v. injection of cyt c in B6 mice produced a 2- to 3-fold reduction in splenic CD8(+) DCs but not in Apaf-1-deficient mice. Functional studies both in vivo and in vitro showed that cyt c profoundly abrogated OVA-specific CD8(+) T cell proliferation through its apoptosis-inducing effect on cross-presenting DCs. More importantly, in vivo injection of cyt c abolished the induction of cytotoxic T lymphocytes to exogenous antigen and reduced subsequent immunity to tumor challenge. In addition, only a proportion of CD8(+) DCs that express abundant IL-12 and Toll-like receptor 3 were efficient cross-presenters. Our data support the hypothesis that cross-presentation in vivo requires cytosolic diversion of endocytosed proteins, conferring cross-presentation specialization to a proportion of CD8(+) DCs. We propose that DCs incapable of such transfer, even within the CD8(+) DC subset, are unable to cross-present. Our model opens an avenue to specifically target cross-presenting DCs in vivo for manipulating cytotoxic T lymphocyte responses toward infections, tumors, and transplants.

  16. Chemical waves in cell and developmental biology.

    Science.gov (United States)

    Deneke, Victoria E; Di Talia, Stefano

    2018-01-09

    Many biological events, such as the propagation of nerve impulses, the synchronized cell cycles of early embryogenesis, and collective cell migration, must be coordinated with remarkable speed across very large distances. Such rapid coordination cannot be achieved by simple diffusion of molecules alone and requires specialized mechanisms. Although active transport can provide a directed and efficient way to travel across subcellular structures, it cannot account for the most rapid examples of coordination found in biology. Rather, these appear to be driven by mechanisms involving traveling waves of chemical activities that are able to propagate information rapidly across biological or physical systems. Indeed, recent advances in our ability to probe the dynamics of signaling pathways are revealing many examples of coordination of cellular and developmental processes through traveling chemical waves. Here, we will review the theoretical principles underlying such waves; highlight recent literature on their role in different contexts, ranging from chemotaxis to development; and discuss open questions and future perspectives on the study of chemical waves as an essential feature of cell and tissue physiology. © 2018 Deneke and Di Talia.

  17. Purification and primary structure of cytochrome c-552 from the cyanobacterium, Synechococcus PCC 6312.

    Science.gov (United States)

    Aitken, A

    1979-11-01

    Cytochrome c-552 (soluble 'cytochrome f') from the unicellular cyanobacterium Synechococcus PCC 6312 (ATCC 27167) was purified and the primary structure determined. The proposed sequence consists of one polypeptide chain of 87 residues. The sequence was determined by a combination of chemical and enzymatic cleavage, manual and automatic sequencing and mass spectroscopy. This is the first amino acid sequence of this cytochrome from a unicellular cyanobacterium to be determined in a study of the variation in primary structure between phylogenetically distant cyanobacteria. The sequence is compared to the primary structures of the cytochrome from filamentous cyanobacteria and from eukaryotic algae. The significance of these sequence comparisons to the current hypotheses concerning the origin of eukaryotic cells and their chloroplasts is discussed.

  18. Interaction studies between periplasmic cytochromes provide insights into extracellular electron transfer pathways of Geobacter sulfurreducens.

    Science.gov (United States)

    Fernandes, Ana P; Nunes, Tiago C; Paquete, Catarina M; Salgueiro, Carlos A

    2017-02-20

    Geobacter bacteria usually prevail among other microorganisms in soils and sediments where Fe(III) reduction has a central role. This reduction is achieved by extracellular electron transfer (EET), where the electrons are exported from the interior of the cell to the surrounding environment. Periplasmic cytochromes play an important role in establishing an interface between inner and outer membrane electron transfer components. In addition, periplasmic cytochromes, in particular nanowire cytochromes that contain at least 12 haem groups, have been proposed to play a role in electron storage in conditions of an environmental lack of electron acceptors. Up to date, no redox partners have been identified in Geobacter sulfurreducens, and concomitantly, the EET and electron storage mechanisms remain unclear. In this work, NMR chemical shift perturbation measurements were used to probe for an interaction between the most abundant periplasmic cytochrome PpcA and the dodecahaem cytochrome GSU1996, one of the proposed nanowire cytochromes in G. sulfurreducens The perturbations on the haem methyl signals of GSU1996 and PpcA showed that the proteins form a transient redox complex in an interface that involves haem groups from two different domains located at the C-terminal of GSU1996. Overall, the present study provides for the first time a clear evidence for an interaction between periplasmic cytochromes that might be relevant for the EET and electron storage pathways in G. sulfurreducens. © 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

  19. Imaging cytochrome C oxidase and FoF1-ATP synthase in mitochondrial cristae of living human cells by FLIM and superresolution microscopy

    Science.gov (United States)

    Foertsch, Franziska; Ilchenko, Mykhailo; Heitkamp, Thomas; Noßmann, Silke; Hoffmann, Birgit; Starke, Ilka; Mrowka, Ralf; Biskup, Christoph; Börsch, Michael

    2017-02-01

    Cytochrome C oxidase and FoF1-ATP synthase constitute complex IV and V, respectively, of the five membrane-bound enzymes in mitochondria comprising the respiratory chain. These enzymes are located in the inner mitochondrial membrane (IMM), which exhibits large invaginations called cristae. According to recent electron cryotomography, FoF1-ATP synthases are located predominantly at the rim of the cristae, while cytochrome C oxidases are likely distributed in planar membrane areas of the cristae. Previous FLIM measurements (K. Busch and coworkers) of complex II and III unravelled differences in the local environment of the membrane enzymes in the cristae. Here, we tagged complex IV and V with mNeonGreen and investigated their mitochondrial nano-environment by FLIM and superresolution microscopy in living human cells. Different lifetimes and anisotropy values were found and will be discussed.

  20. Heme Binding Biguanides Target Cytochrome P450-Dependent Cancer Cell Mitochondria.

    Science.gov (United States)

    Guo, Zhijun; Sevrioukova, Irina F; Denisov, Ilia G; Zhang, Xia; Chiu, Ting-Lan; Thomas, Dafydd G; Hanse, Eric A; Cuellar, Rebecca A D; Grinkova, Yelena V; Langenfeld, Vanessa Wankhede; Swedien, Daniel S; Stamschror, Justin D; Alvarez, Juan; Luna, Fernando; Galván, Adela; Bae, Young Kyung; Wulfkuhle, Julia D; Gallagher, Rosa I; Petricoin, Emanuel F; Norris, Beverly; Flory, Craig M; Schumacher, Robert J; O'Sullivan, M Gerard; Cao, Qing; Chu, Haitao; Lipscomb, John D; Atkins, William M; Gupta, Kalpna; Kelekar, Ameeta; Blair, Ian A; Capdevila, Jorge H; Falck, John R; Sligar, Stephen G; Poulos, Thomas L; Georg, Gunda I; Ambrose, Elizabeth; Potter, David A

    2017-10-19

    The mechanisms by which cancer cell-intrinsic CYP monooxygenases promote tumor progression are largely unknown. CYP3A4 was unexpectedly associated with breast cancer mitochondria and synthesized arachidonic acid (AA)-derived epoxyeicosatrienoic acids (EETs), which promoted the electron transport chain/respiration and inhibited AMPKα. CYP3A4 knockdown activated AMPKα, promoted autophagy, and prevented mammary tumor formation. The diabetes drug metformin inhibited CYP3A4-mediated EET biosynthesis and depleted cancer cell-intrinsic EETs. Metformin bound to the active-site heme of CYP3A4 in a co-crystal structure, establishing CYP3A4 as a biguanide target. Structure-based design led to discovery of N1-hexyl-N5-benzyl-biguanide (HBB), which bound to the CYP3A4 heme with higher affinity than metformin. HBB potently and specifically inhibited CYP3A4 AA epoxygenase activity. HBB also inhibited growth of established ER(+) mammary tumors and suppressed intratumoral mTOR. CYP3A4 AA epoxygenase inhibition by biguanides thus demonstrates convergence between eicosanoid activity in mitochondria and biguanide action in cancer, opening a new avenue for cancer drug discovery. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. A novel alkaloid, evodiamine causes nuclear localization of cytochrome-c and induces apoptosis independent of p53 in human lung cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Mohan, Vijay [School of Life Sciences, Central University of Gujarat, Gandhinagar, Gujarat (India); Agarwal, Rajesh [Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado Denver, Aurora, CO (United States); Singh, Rana P., E-mail: ranaps@hotmail.com [School of Life Sciences, Central University of Gujarat, Gandhinagar, Gujarat (India); Cancer Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi (India)

    2016-09-02

    Lung cancer is the most frequently diagnosed malignancy that contributes to high proportion of deaths globally among patients who die due to cancer. Chemotherapy remains the common mode of treatment for lung cancer patients though with limited success. We assessed the biological effects and associated molecular changes of evodiamine, a plant alkaloid, on human lung cancer A549 and H1299 cells along with other epithelial cancer and normal lung SAEC cells. Our data showed that 20–40 μM evodiamine treatment for 24–48 h strongly (up to 73%, P < 0.001) reduced the growth and survival of these cancer cells. However, it also moderately inhibited growth and survival of SAEC cells. A strong inhibition (P < 0.001) was observed on clonogenicity of A549 cells. Further, evodiamine increased (4-fold) mitochondrial membrane depolarization with 6-fold increase in apoptosis and a slight increase in Bax/Bcl-2 ratio. It increased the cytochrome-c release from mitochondria into the cytosol as well as nucleus. Cytosolic cytochrome-c activated cascade of caspase-9 and caspase-3 intrinsic pathway, however, DR5 and caspase-8 extrinsic pathway was also activated which could be due to nuclear cytochrome-c. Pan-caspase inhibitor (z-VAD.fmk) partially reversed evodiamine induced apoptosis. An increase in p53 as well as its serine 15 phosphorylation was also observed. Pifithrin-α, a p53 inhibitor, slightly inhibited growth of A549 cells and under p53 inhibitory condition evodiamine-induced apoptosis could not be reversed. Together these findings suggest that evodiamine is a strong inducer of apoptosis in lung epithelial cancer cells independent of their p53 status and that could involve both intrinsic as well as extrinsic pathway of apoptosis. Thus evodiamine could be a potential anticancer agent against lung cancer. - Highlights: • Evodiamine, a novel plant alkaloid, relatively selectively inhibited growth and survival of human lung cancer cells. • Increased cancer cell

  2. Replacement of immobilised cell bioreactors by smaller immobilised enzyme bioreactors: unique-outcome predictability for cytochromes P450 isoforms?

    Science.gov (United States)

    Wiseman, Alan

    2003-10-01

    Both immobilized enzymes (IME) and immobilized cells (IMC) are acceptable as the biocatalysts essential for the attainment of rapid rates of bioconversion in bioreactors. IMC can display higher than expected cellular permeability whilst IME can exhibit high catalytic constant (kcat/Km) despite limitations on substrate utilisation due to an unstired diffusion layer of solvent. Scale-down switching from IMC to IME involves the replacement of high-volume biotechnology by low-volume biotechnology, sometimes using IME mimics in partially non-aqueous solvent systems. Highly purified IME systems covalently immobilised to particles of, for instance, microcrystalline cellulose or porous glass, can retain both the hydrophilic and hydrophobic intermediate products in situ of the chosen sequence of enzyme reactions. These bioconversions, therefore, are as efficient as those with IMC where enzymes are often particle- or membrane-bound so that even hydrophilic intermediates are not released rapidly into solution. This mimicry of in vivo biosynthetic pathways that are compartmentalised in vivo (e.g. of lysosomes, mitochondria and endoplasmic reticulum) can replace larger IMC by IME especially in application of up to 2700 cytochromes P450 isoforms in bioprocessing. In silico investigation of appropriate model IME systems, in comparison with IMC systems, will be needed to define the optimal bioreactor configuration and parameters of operation, such as pH, T and oxygen mass transfer rate (OTR). The application solely of hazop (applied hazard and operability concepts) may, nevertheless, not be recommended to replace fully the in silico and real-lab pilot-scale and scale studies. Here, food-safe bioprocessing has to be achieved without incorporation of recognised biohazards; especially in the form of unacceptable levels of toxic metals that promote a risk-analysis uncertainty.

  3. Overexpression of pregnane X and glucocorticoid receptors and the regulation of cytochrome P450 in human epileptic brain endothelial cells.

    Science.gov (United States)

    Ghosh, Chaitali; Hossain, Mohammed; Solanki, Jesal; Najm, Imad M; Marchi, Nicola; Janigro, Damir

    2017-04-01

    Recent evidence suggests a metabolic contribution of cytochrome P450 enzymes (CYPs) to the drug-resistant phenotype in human epilepsy. However, the upstream molecular regulators of CYP in the epileptic brain remain understudied. We therefore investigated the expression and function of pregnane xenobiotic (PXR) and glucocorticoid (GR) nuclear receptors in endothelial cells established from post-epilepsy surgery brain samples. PXR/GR localization was evaluated by immunohistochemistry in specimens from subjects who underwent temporal lobe resections to relieve drug-resistant seizures. We used primary cultures of endothelial cells obtained from epileptic brain tissues (EPI-ECs; n = 8), commercially available human brain microvascular endothelial cells (HBMECs; n = 8), and human hepatocytes (n = 3). PXR/GR messenger RNA (mRNA) levels in brain ECs was initially determined by complementary DNA (cDNA) microarrays. The expression of PXR/GR proteins was quantified by Western blot. PXR and GR silencing was performed in EPI-ECs (n = 4), and the impact on downstream CYP expression was determined. PXR/GR expression was detected by immunofluorescence in ECs and neurons in the human temporal lobe samples analyzed. Elevated mRNA and protein levels of PXR and GR were found in EPI-ECs versus control HBMECs. Hepatocytes, used as a positive control, displayed the highest levels of PXR/GR expression. We confirmed expression of PXR/GR in cytoplasmic-nuclear subcellular fractions, with a significant increase of PXR/GR in EPI-ECs versus controls. CYP3A4, CYP2C9, and CYP2E1 were overexpressed in EPI-ECs versus control, whereas CYP2D6 and CYP2C19 were downregulated or absent in EPI-ECs. GR silencing in EPI-ECs led to decreased CYP3A4, CYP2C9, and PXR expression. PXR silencing in EPI-ECs resulted in the specific downregulation of CYP3A4 expression. Our results indicate increased PXR and GR in primary ECs derived from human epileptic brains. PXR or GR may be responsible for a local drug brain

  4. Metallic nickel nano- and fine particles induce JB6 cell apoptosis through a caspase-8/AIF mediated cytochrome c-independent pathway

    Directory of Open Access Journals (Sweden)

    Castranova Vincent

    2009-04-01

    Full Text Available Abstract Background Carcinogenicity of nickel compounds has been well documented. However, the carcinogenic effect of metallic nickel is still unclear. The present study investigates metallic nickel nano- and fine particle-induced apoptosis and the signal pathways involved in this process in JB6 cells. The data obtained from this study will be of benefit for elucidating the pathological and carcinogenic potential of metallic nickel particles. Results Using 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT assay, we found that metallic nickel nanoparticles exhibited higher cytotoxicity than fine particles. Both metallic nickel nano- and fine particles induced JB6 cell apoptosis. Metallic nickel nanoparticles produced higher apoptotic induction than fine particles. Western-blot analysis showed an activation of proapoptotic factors including Fas (CD95, Fas-associated protein with death domain (FADD, caspase-8, death receptor 3 (DR3 and BID in apoptotic cells induced by metallic nickel particles. Immunoprecipitation (IP western blot analysis demonstrated the formation of the Fas-related death-inducing signaling complex (DISC in the apoptotic process. Furthermore, lamin A and beta-actin were cleaved. Moreover, we found that apoptosis-inducing factor (AIF was up-regulated and released from mitochondria to cytoplasm. Interestingly, although an up-regulation of cytochrome c was detected in the mitochondria of metallic nickel particle-treated cells, no cytochrome c release from mitochondria to cytoplasm was found. In addition, activation of antiapoptotic factors including phospho-Akt (protein kinase B and Bcl-2 was detected. Further studies demonstrated that metallic nickel particles caused no significant changes in the mitochondrial membrane permeability after 24 h treatment. Conclusion In this study, metallic nickel nanoparticles caused higher cytotoxicity and apoptotic induction than fine particles in JB6 cells. Apoptotic cell death

  5. Cell-in-Shell Hybrids: Chemical Nanoencapsulation of Individual Cells.

    Science.gov (United States)

    Park, Ji Hun; Hong, Daewha; Lee, Juno; Choi, Insung S

    2016-05-17

    Nature has developed a fascinating strategy of cryptobiosis ("secret life") for counteracting the stressful, and often lethal, environmental conditions that fluctuate sporadically over time. For example, certain bacteria sporulate to transform from a metabolically active, vegetative state to an ametabolic endospore state. The bacterial endospores, encased within tough biomolecular shells, withstand the extremes of harmful stressors, such as radiation, desiccation, and malnutrition, for extended periods of time and return to a vegetative state by breaking their protective shells apart when their environment becomes hospitable for living. Certain ciliates and even higher organisms, for example, tardigrades, and others are also found to adopt a cryptobiotic strategy for survival. A common feature of cryptobiosis is the structural presence of tough sheaths on cellular structures. However, most cells and cellular assemblies are not "spore-forming" and are vulnerable to the outside threats. In particular, mammalian cells, enclosed with labile lipid bilayers, are highly susceptible to in vitro conditions in the laboratory and daily life settings, making manipulation and preservation difficult outside of specialized conditions. The instability of living cells has been a main bottleneck to the advanced development of cell-based applications, such as cell therapy and cell-based sensors. A judicious question arises: can cellular tolerance against harmful stresses be enhanced by simply forming cell-in-shell hybrid structures? Experimental results suggest that the answer is yes. A micrometer-sized "Iron Man" can be generated by chemically forming an ultrathin (in-shell structures found in nature, for example, bacterial endospores. Bioinspired silicification and phenolics-based coatings are, so far, the main approaches to the formation of cytoprotective cell-in-shell hybrids, because they ensure cell viability during encapsulations and also generate durable nanoshells on cell

  6. Role of p38 MAPK activation and mitochondrial cytochrome-c release in allicin-induced apoptosis in SK-N-SH cells.

    Science.gov (United States)

    Zhuang, Jianhui; Li, Yu; Chi, Yufen

    2016-04-01

    Here, we investigate the apoptotic effect of allicin, the predominant component of freshly crushed garlic, on neuroblastoma cells. In this paper, the authors have first assessed the effect of allicin on human neuroblastoma SK-N-SH cells and then investigated the underlying mechanism. The results indicate that allicin suppresses SK-N-SH cell growth in a dose-dependent and time-dependent manner and that 5 μmol/l of allicin leads to a significant increase in apoptotic rate with annexin-V/PI double staining. Western blot analysis shows that treatment with allicin-induced apoptosis through activation of caspases-3 and 9. Phosphorylation of p38 MAPK contributes to allicin-induced apoptosis upstream of caspase activation. Using p38 MAPK inhibitor, the authors discovered that p38 MAPK activation subsequently induces the release of cytochrome-c from mitochondria into the cytosol. Taken together, the results demonstrate that allicin can activate the p38 MAPK pathway, which leads to mitochondrial release of cytochrome-c, thus inducing SK-N-SH cell apoptosis. Overall, this study suggests that allicin may be used as one of the novel pharmacological treatment strategies in neuroblastoma.

  7. Protein and DNA technologies for functional expression of membrane-associated cytochromes P450 in bacterial cell factories

    DEFF Research Database (Denmark)

    Vazquez Albacete, Dario

    450 engineering guidelines and serves as platform to improve performance of microbial cells, thereby boosting recombinant production of complex plant P450-derived biochemicals. The knowledge generated, could guide future reconstruction of functional plant metabolic pathways leading to high valuable...... potential as medicines, fuels or food for humans. Plants conquered different environments thereby developing adaptation strategies based on the biosynthesis of a myriad of compounds. Unfortunately they are present in small amounts in plants and are too complex and to produce by organic chemical synthesis......The heavy dependence and massive consumption of fossil fuels by humans is changing our environment very rapidly. Some of the side effects of industrial activity include the pollution of the natural resources we rely on, and the reduction of biodiversity. Some chemicals found in nature exhibit great...

  8. Phase I/II clinical trial of encapsulated, cytochrome P450 expressing cells as local activators of cyclophosphamide to treat spontaneous canine tumours.

    Directory of Open Access Journals (Sweden)

    Monika Michałowska

    Full Text Available Based upon promising preclinical studies, a clinical trial was performed in which encapsulated cells overexpressing cytochrome P450 enzyme isoform 2B1 were implanted around malignant mammary tumours arising spontaneously in dogs. The dogs were then given cyclophosphamide, one of the standard chemotherapeutic agents used for the treatment of mammary tumours. The dogs were assessed for a number of clinical parameters as well as for reduction in tumour size. The treatment was well tolerated with no evidence of adverse reactions or side effects being associated with the administration of the encapsulated cells. Reductions in tumour size of more than 50% were observed for 6 out of the 11 tumours analysed while 5 tumours showing minor responses, i.e. stable disease. In contrast, the tumours that received cyclophosphamide alone showed only stable disease. Taken together, this data suggests that encapsulated cytochrome P450 expressing cells combined with chemotherapy may be useful in the local treatment of a number of dog mammary tumours and support the performance of further clinical studies to evaluate this new treatment.

  9. Oxyphil cell metaplasia in the parathyroids is characterized by somatic mitochondrial DNA mutations in NADH dehydrogenase genes and cytochrome c oxidase activity-impairing genes.

    Science.gov (United States)

    Müller-Höcker, Josef; Schäfer, Sabine; Krebs, Stefan; Blum, Helmut; Zsurka, Gábor; Kunz, Wolfram S; Prokisch, Holger; Seibel, Peter; Jung, Andreas

    2014-11-01

    Oxyphil cell transformation of epithelial cells due to the accumulation of mitochondria occurs often during cellular aging. To understand the pathogenic mechanisms, we studied mitochondrial DNA (mtDNA) alterations in the three cell types of the parathyroids using multiplex real-time PCR and next-generation sequencing. mtDNA was analyzed from cytochrome c oxidase (COX)-positive and COX-negative areas of 19 parathyroids. Mitochondria-rich pre-oxyphil/oxyphil cells were more prone to develop COX defects than the mitochondria-poor clear chief cells (P cells. In COX deficiency, the increase was even more pronounced, and COX-negative oxyphil cells had approximately two times more mtDNA than COX-positive oxyphil cells (P cells and, therefore, could be essential for inducing oxyphil cell transformation by increasing mtDNA/mitochondrial biogenesis. In contrast, COX-negative cells predominantly harbored mutations in the MT-CO1 and MT-CO3 genes and in regulatory mtDNA elements, but only rarely NADH dehydrogenase mutations. Thus, multiple hits in NADH dehydrogenase and COX activity-impairing genes represent the molecular basis of oxyphil cell transformation in the parathyroids.

  10. Cell-mediated mutagenesis and cell transformation by chemical carcinogens

    Energy Technology Data Exchange (ETDEWEB)

    Huberman, E.; Langenbach, R.

    1977-01-01

    Results are reported from studies that showed that mutagenesis of mammalian cells can be achieved by carcinogenic polycyclic hydrocarbons, nitrosamines, and aflatoxins when tested in the presence of fibroblasts and hepatocytes which are able to metabolize these carcinogens. Further, we have found that there is a relationship between the degree of mutant induction and the degree of carcinogenicity of the different chemicals tested. By simultaneously measuring the frequency of cell transformation and the frequency of mutation at one locus (ouabain resistance) in the same cell system, it was possible to estimate the genetic target site for cell transformation. The results indicated that the target site for transformation is approximately 20 times larger than that determined for ouabain resistance. The results suggest that cell transformation may be due to a mutational event and the mutation can occur in one out of a small number of the same or different genes, and that the cell-mediated mutagenesis approach may be a valuable means of detecting tissue-specific carcinogens.

  11. Cell surface analysis and adhesion of chemically modified streptococci

    NARCIS (Netherlands)

    van der Mei, HC; van de Belt-Gritter, B; Doyle, RJ; Busscher, HJ

    2001-01-01

    In this paper, streptococcal cell surfaces are chemically modified, and the effects of the modification on cell surface hydrophobicity and charge, together with adhesion to hexadecane are determined. Acetic and succinic anhydrides, neutralizing or converting ammonium groups into negatively charged

  12. Testing Turing’s theory of morphogenesis in chemical cells

    Science.gov (United States)

    Tompkins, Nathan; Li, Ning; Girabawe, Camille; Heymann, Michael; Ermentrout, G. Bard; Epstein, Irving R.; Fraden, Seth

    2014-01-01

    Alan Turing, in “The Chemical Basis of Morphogenesis” [Turing AM (1952) Philos Trans R Soc Lond 237(641):37–72], described how, in circular arrays of identical biological cells, diffusion can interact with chemical reactions to generate up to six periodic spatiotemporal chemical structures. Turing proposed that one of these structures, a stationary pattern with a chemically determined wavelength, is responsible for differentiation. We quantitatively test Turing’s ideas in a cellular chemical system consisting of an emulsion of aqueous droplets containing the Belousov–Zhabotinsky oscillatory chemical reactants, dispersed in oil, and demonstrate that reaction-diffusion processes lead to chemical differentiation, which drives physical morphogenesis in chemical cells. We observe five of the six structures predicted by Turing. In 2D hexagonal arrays, a seventh structure emerges, incompatible with Turing’s original model, which we explain by modifying the theory to include heterogeneity. PMID:24616508

  13. Increased oxidative stress and cytotoxicity by hydrogen sulfide in HepG2 cells overexpressing cytochrome P450 2E1

    Science.gov (United States)

    Caro, Andres A.; Thompson, Sarah; Tackett, Jonathan

    2013-01-01

    The main objectives of this work were to evaluate the effects of hydrogen sulfide on oxidative stress and cytotoxicity parameters in HepG2 cells and to assess the extent to which cytochrome P450 2E1 (CYP2E1) activity modulates the effects of hydrogen sulfide on oxidative stress and cytotoxicity. Sodium hydrosulfide (NaHS) caused time- and concentration-dependent cytotoxicity in both non-P450-expressing HepG2 cells (C34 cells) and CYP2E1-overexpressing HepG2 cells (E47 cells); however, NaHS-dependent cytotoxicity was higher in E47 than C34 cells. Cytotoxicity by NaHS in C34 and E47 cells was mainly necrotic in nature and associated with an early decrease in mitochondrial membrane potential. NaHS caused increased oxidation of lipophilic (C11-BODIPY581/591) and hydrophilic (DCFH-DA) probes only in E47 cells, at a time point prior to overt cytotoxicity. Trolox, an amphipathic antioxidant, partially inhibited both the cytotoxicity and the increased oxidative stress detected in E47 cells exposed to NaHS. Cell-permeable iron chelators and CYP2E1 inhibitors significantly inhibited the oxidation of C11-BODIPY581/591 in E47 cells in the presence of NaHS. NaHS produced lipid peroxidation and cytotoxicity in E47 cells supplemented with a representative polyunsaturated fatty acid (docosahexaenoic acid) but not in C34 cells; these effects were inhibited by α-tocopherol, a lipophilic antioxidant. These data suggest that CYP2E1 enhances H2S-dependent cytotoxicity in HepG2 cells through the generation of iron-dependent oxidative stress and lipid peroxidation. PMID:21850523

  14. 7,12-Dimethylbenzanthracene induces apoptosis in RL95-2 human endometrial cancer cells: Ligand-selective activation of cytochrome P450 1B1

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji Young [Department of Anatomy and Cell Biology, College of Medicine, Dong-A University, Busan 602-714 (Korea, Republic of); Medical Research Science Center, Dong-A University, Busan 602-714 (Korea, Republic of); Lee, Seung Gee [Department of Anatomy and Cell Biology, College of Medicine, Dong-A University, Busan 602-714 (Korea, Republic of); Mitochondria Hub Regulation Center, Dong-A University, Busan 602-714 (Korea, Republic of); Chung, Jin-Yong [Department of Anatomy and Cell Biology, College of Medicine, Dong-A University, Busan 602-714 (Korea, Republic of); Medical Research Science Center, Dong-A University, Busan 602-714 (Korea, Republic of); Kim, Yoon-Jae [Department of Anatomy and Cell Biology, College of Medicine, Dong-A University, Busan 602-714 (Korea, Republic of); Mitochondria Hub Regulation Center, Dong-A University, Busan 602-714 (Korea, Republic of); Park, Ji-Eun [Department of Anatomy and Cell Biology, College of Medicine, Dong-A University, Busan 602-714 (Korea, Republic of); Medical Research Science Center, Dong-A University, Busan 602-714 (Korea, Republic of); Oh, Seunghoon [Department of Physiology, College of Medicine, Dankook University, Cheonan 330-714 (Korea, Republic of); Lee, Se Yong [Department of Obstetrics and Gynecology, Busan Medical Center, Busan 611-072 (Korea, Republic of); Choi, Hong Jo [Department of General Surgery, College of Medicine, Dong-A University, Busan 602-714 (Korea, Republic of); Yoo, Young Hyun, E-mail: yhyoo@dau.ac.kr [Department of Anatomy and Cell Biology, College of Medicine, Dong-A University, Busan 602-714 (Korea, Republic of); Mitochondria Hub Regulation Center, Dong-A University, Busan 602-714 (Korea, Republic of); Medical Research Science Center, Dong-A University, Busan 602-714 (Korea, Republic of); and others

    2012-04-15

    7,12-Dimethylbenzanthracene (DMBA), a polycyclic aromatic hydrocarbon, exhibits mutagenic, carcinogenic, immunosuppressive, and apoptogenic properties in various cell types. To achieve these functions effectively, DMBA is modified to its active form by cytochrome P450 1 (CYP1). Exposure to DMBA causes cytotoxicity-mediated apoptosis in bone marrow B cells and ovarian cells. Although uterine endometrium constitutively expresses CYP1A1 and CYP1B1, their apoptotic role after exposure to DMBA remains to be elucidated. Therefore, we chose RL95-2 endometrial cancer cells as a model system for studying DMBA-induced cytotoxicity and cell death and hypothesized that exposure to DMBA causes apoptosis in this cell type following CYP1A1 and/or CYP1B1 activation. We showed that DMBA-induced apoptosis in RL95-2 cells is associated with activation of caspases. In addition, mitochondrial changes, including decrease in mitochondrial potential and release of mitochondrial cytochrome c into the cytosol, support the hypothesis that a mitochondrial pathway is involved in DMBA-induced apoptosis. Exposure to DMBA upregulated the expression of AhR, Arnt, CYP1A1, and CYP1B1 significantly; this may be necessary for the conversion of DMBA to DMBA-3,4-diol-1,2-epoxide (DMBA-DE). Although both CYP1A1 and CYP1B1 were significantly upregulated by DMBA, only CYP1B1 exhibited activity. Moreover, knockdown of CYP1B1 abolished DMBA-induced apoptosis in RL95-2 cells. Our data show that RL95-2 cells are susceptible to apoptosis by exposure to DMBA and that CYP1B1 plays a pivotal role in DMBA-induced apoptosis in this system. -- Highlights: ► Cytotoxicity-mediated apoptogenic action of DMBA in human endometrial cancer cells. ► Mitochondrial pathway in DMBA-induced apoptosis of RL95-2 endometrial cancer cells. ► Requirement of ligand-selective activation of CYP1B1 in DMBA-induced apoptosis.

  15. White light emitting diode suppresses proliferation and induces apoptosis in hippocampal neuron cells through mitochondrial cytochrome c oxydase-mediated IGF-1 and TNF-α pathways.

    Science.gov (United States)

    Yang, Yang; Zong, Yibo; Sun, Qinwei; Jia, Yimin; Zhao, Ruqian

    2017-12-01

    Light emitting diode (LED) light has been tested to treat traumatic brain injury, neural degenerative diseases and psychiatric disorders. Previous studies indicate that blue LED light affects cell proliferation and apoptosis in photosensitive cells and cancer cells. In this study, we demonstrate that white LED light exposure impaired proliferation and induced apoptosis in HeLa and HT-22 hippocampal neural cells, but not C2C12 cells. Furthermore, the mechanisms underlying the effect of white LED light exposure on HT-22 cells were elucidated. In HeLa and HT-22 cells, white LED light activated mitochondrial cytochrome c oxidase (Cco), in association with enhanced ATP synthase activity and elevated intracellular ATP concentration. Also, reactive oxygen species (ROS) and nitric oxide (NO) production were increased, accompanied by higher calcium concentration and lower mitochondrial membrane potential. HT-22 cells exposed to white LED light for 24h showed reduced viability, with higher apoptotic rate and a cell cycle arrest at G0/G1 phase. Concurrently, the mRNA expression and the concentration of IGF-1 were decreased, while that of TNF-α were increased, in light-exposed cells, which was supported by the luciferase activity of both gene promoters. The down-stream mitogen-activated protein kinase (MAPK), AKT/mTOR pathways were inhibited, in association with an activation of apoptotic caspase 3. N-Acetylcysteine, a ROS scavenger, protected the cells from LED light-induced cellular damage, with rescued cell viability and restored mRNA expression of IGF-1 and TNF-α. Our data demonstrate that white LED light suppresses proliferation and induces apoptosis in hippocampal neuron cells through mitochondrial Cco/ROS-mediated IGF-1 and TNF-α pathways. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Chemical modification of lysine residues in cytochrome P450LM2 (P450IIB4): influence on heme liganding of arylamines.

    Science.gov (United States)

    Golly, I; Hlavica, P

    1992-01-01

    Treatment of cytochrome P450LM2 with fluorescein isothiocyanate to introduce up to two equivalents of fluorophore per polypeptide chain resulted in the selective derivatization of lysine residues. CD-spectral measurements revealed the overall conformation as well as the immediate heme environment of the hemoprotein to remain unaffected by attachment of the label. Modification caused decreased affinity of p-phenylenediamine and other 4-substituted anilines for the heme site, whereas there was a rise in the extent of substrate interaction. Experiments with pigment containing acetylated lysines gave analogous results, suggesting that the observed phenomenon was due to charge neutralization. There was linear correlation between the Hammett sigma P values and both the optical dissociation constants for arylamine binding to intact enzyme and the dipole moments of the anilines, indicating that basicity along with electronic factors controlled heme liganding; lipophilicity appeared to be of minor importance. Introduction of fluorescein isothiocyanate into the oxygenase was found to influence the bond-making process through modulating basicity of the nitrogenous compounds, but perturbation of optimal spacial orientation of the amine nitrogen toward the heme iron also might have been operative. The lysines studied seem to represent metabolically inactive elements of the substrate channel located on the cytosolic surface of the aggregates, as evidenced by steady-state fluorescence measurements. A hydrophilic segment in the cytochrome P450LM2 molecule that would accommodate the critical residues is discussed.

  17. Sustained induction of cytochrome P4501A1 in human hepatoma cells by co-exposure to benzo[a]pyrene and 7H-dibenzo[c,g]carbazole underlies the synergistic effects on DNA adduct formation

    Energy Technology Data Exchange (ETDEWEB)

    Gábelová, Alena, E-mail: alena.gabelova@savba.sk [Cancer Research Institute, Slovak Academy of Sciences, Vlárska 7, 833 91 Bratislava (Slovakia); Poláková, Veronika [Cancer Research Institute, Slovak Academy of Sciences, Vlárska 7, 833 91 Bratislava (Slovakia); Prochazka, Gabriela [Department of Biosciences and Nutrition, Karolinska Institute, Novum, SE-141 83 Huddinge (Sweden); Department of Medical Epidemiology and Biostatistics, Karolinska Institute, SE-171 77 Stockholm (Sweden); Kretová, Miroslava; Poloncová, Katarína; Regendová, Eva; Luciaková, Katarína [Cancer Research Institute, Slovak Academy of Sciences, Vlárska 7, 833 91 Bratislava (Slovakia); Segerbäck, Dan [Department of Biosciences and Nutrition, Karolinska Institute, Novum, SE-141 83 Huddinge (Sweden)

    2013-08-15

    To gain a deeper insight into the potential interactions between individual aromatic hydrocarbons in a mixture, several benzo[a]pyrene (B[a]P) and 7H-dibenzo[c,g]carbazole (DBC) binary mixtures were studied. The biological activity of the binary mixtures was investigated in the HepG2 and WB-F344 liver cell lines and the Chinese hamster V79 cell line that stably expresses the human cytochrome P4501A1 (hCYP1A1). In the V79 cells, binary mixtures, in contrast to individual carcinogens, caused a significant decrease in the levels of micronuclei, DNA adducts and gene mutations, but not in cell survival. Similarly, a lower frequency of micronuclei and levels of DNA adducts were found in rat liver WB-F344 cells treated with a binary mixture, regardless of the exposure time. The observed antagonism between B[a]P and DBC may be due to an inhibition of Cyp1a1 expression because cells exposed to B[a]P:DBC showed a decrease in Cyp1a1 mRNA levels. In human liver HepG2 cells exposed to binary mixtures for 2 h, a reduction in micronuclei frequency was also found. However, after a 24 h treatment, synergism between B[a]P and DBC was determined based on DNA adduct formation. Accordingly, the up-regulation of CYP1A1 expression was detected in HepG2 cells exposed to B[a]P:DBC. Our results show significant differences in the response of human and rat cells to B[a]P:DBC mixtures and stress the need to use multiple experimental systems when evaluating the potential risk of environmental pollutants. Our data also indicate that an increased expression of CYP1A1 results in a synergistic effect of B[a]P and DBC in human cells. As humans are exposed to a plethora of noxious chemicals, our results have important implications for human carcinogenesis. - Highlights: • B[a]P:DBC mixtures were less genotoxic in V79MZh1A1 cells than B[a]P and DBC alone. • An antagonism between B[a]P and DBC was determined in rat liver WB-F344 cells. • The inhibition of CYP1a1 expression by B[a]P:DBC mixture

  18. Cell-mediated mutagenesis and cell transformation of mammalian cells by chemical carcinogens. [Rats, hamsters

    Energy Technology Data Exchange (ETDEWEB)

    Huberman, E.; Langenbach, R.

    1977-01-01

    We have developed a cell-mediated mutagenesis assay in which cells with the appropriate markers for mutagenesis are co-cultivated with either lethally irradiated rodent embryonic cells that can metabolize carcinogenic hydrocarbons or with primary rat liver cells that can metabolize chemicals carcinogenic to the liver. During co-cultivation, the reactive metabolites of the procarcinogen appear to be transmitted to the mutable cells and induce mutations in them. Assays of this type make it possible to demonstrate a relationship between carcinogenic potency of the chemicals and their ability to induce mutations in mammalian cells. In addition, by simultaneously comparing the frequencies of transformation and mutation induced in normal diploid hamster cells by benzo(a)pyrene (BP) and one of its metabolites, it is possible to estimate the genetic target size for cell transformation in vitro.

  19. Antiproliferative effect of the Ginkgo biloba extract is associated with the enhancement of cytochrome P450 1B1 expression in estrogen receptor-negative breast cancer cells

    Science.gov (United States)

    ZHAO, XIAO-DAN; DONG, NI; MAN, HONG-TAO; FU, ZHONG-LIN; ZHANG, MEI-HONG; KOU, SHUANG; MA, SHI-LIANG

    2013-01-01

    Ginkgo biloba is a dioecious tree and its extract is a complex mixture that has been used for thousands of years to treat a variety of ailments in traditional Chinese medicine. The aim of this study was to present our observations on the inhibitory effects of different Ginkgo biloba extracts on human breast cancer cell proliferation and growth. Our results demonstrated that treatment of MCF-7 and MDA-MB-231 human breast cancer cells with Ginkgo biloba leaves and ginkgo fruit extract inhibited cell proliferation. It was also observed that this inhibition was accompanied by the enhancement of cytochrome P450 (CYP) 1B1 expression in MDA-MB-231 cells. In addition, treatment with ginkgo fruit extract resulted in a higher CYP1B1 expression in MDA-MB-231 cells compared to treatment with the Ginkgo biloba leaves extract. Our results suggested that the inhibitory effects of the Ginkgo biloba extract on estrogen receptor-negative breast cancer proliferation and the induction of CYP1B1 expression may be exerted through an alternative pathway, independent of the estrogen receptor or the aryl hydrocarbon receptor pathway. PMID:24649031

  20. Structure-Function, Stability, and Chemical Modification of the Cyanobacterial Cytochrome b[subscript 6]f Complex from Nostoc sp. PCC 7120

    Energy Technology Data Exchange (ETDEWEB)

    Baniulis, Danas; Yamashita, Eiki; Whitelegge, Julian P.; Zatsman, Anna I.; Hendrich, Michael P.; Hasan, S. Saif; Ryan, Christopher M.; Cramer, William A.; (Semel); (Purdue); (Osaka)

    2009-06-08

    The crystal structure of the cyanobacterial cytochrome b{sub 6}f complex has previously been solved to 3.0-{angstrom} resolution using the thermophilic Mastigocladus laminosus whose genome has not been sequenced. Several unicellular cyanobacteria, whose genomes have been sequenced and are tractable for mutagenesis, do not yield b{sub 6}f complex in an intact dimeric state with significant electron transport activity. The genome of Nostoc sp. PCC 7120 has been sequenced and is closer phylogenetically to M. laminosus than are unicellular cyanobacteria. The amino acid sequences of the large core subunits and four small peripheral subunits of Nostoc are 88 and 80% identical to those in the M. laminosus b{sub 6}f complex. Purified b{sub 6}f complex from Nostoc has a stable dimeric structure, eight subunits with masses similar to those of M. laminosus, and comparable electron transport activity. The crystal structure of the native b{sub 6}f complex, determined to a resolution of 3.0{angstrom} (PDB id: 2ZT9), is almost identical to that of M. laminosus. Two unique aspects of the Nostoc complex are: (i) a dominant conformation of heme b{sub p} that is rotated 180 deg. about the {alpha}- and {gamma}-meso carbon axis relative to the orientation in the M. laminosus complex and (ii) acetylation of the Rieske iron-sulfur protein (PetC) at the N terminus, a post-translational modification unprecedented in cyanobacterial membrane and electron transport proteins, and in polypeptides of cytochrome bc complexes from any source. The high spin electronic character of the unique heme cn is similar to that previously found in the b{sub 6}f complex from other sources.

  1. Plant cell tissue culture: A potential source of chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Scott, C.D.; Dougall, D.K.

    1987-08-01

    Higher plants produce many industrially important products. Among these are drugs and medicinal chemicals, essential oils and flavors, vegetable oils and fats, fine and specialty chemicals, and even some commodity chemicals. Although, currently, whole-plant extraction is the primary means of harvesting these materials, the advent of plant cell tissue culture could be a much more effective method of producing many types of phytochemicals. The use of immobilized plant cells in an advanced bioreactor configuration with excretion of the product into the reactor medium may represent the most straightforward way of commercializing such techniques for lower-value chemicals. Important research and development opportunities in this area include screening for plant cultures for nonmedical, lower-value chemicals; understanding and controlling plant cell physiology and biochemistry; optimizing effective immobilization methods; developing more efficient bioreactor concepts; and perfecting product extraction and purification techniques. 62 refs., 2 figs.

  2. In vitro Cell Culture Model for Toxic Inhaled Chemical Testing

    Science.gov (United States)

    Ahmad, Shama; Ahmad, Aftab; Neeves, Keith B.; Hendry-Hofer, Tara; Loader, Joan E.; White, Carl W.; Veress, Livia

    2014-01-01

    Cell cultures are indispensable to develop and study efficacy of therapeutic agents, prior to their use in animal models. We have the unique ability to model well differentiated human airway epithelium and heart muscle cells. This could be an invaluable tool to study the deleterious effects of toxic inhaled chemicals, such as chlorine, that can normally interact with the cell surfaces, and form various byproducts upon reacting with water, and limiting their effects in submerged cultures. Our model using well differentiated human airway epithelial cell cultures at air-liqiuid interface circumvents this limitation as well as provides an opportunity to evaluate critical mechanisms of toxicity of potential poisonous inhaled chemicals. We describe enhanced loss of membrane integrity, caspase release and death upon toxic inhaled chemical such as chlorine exposure. In this article, we propose methods to model chlorine exposure in mammalian heart and airway epithelial cells in culture and simple tests to evaluate its effect on these cell types. PMID:24837339

  3. Control of electron transfer in the cytochrome system of mitochondria by pH, transmembrane pH gradient and electrical potential. The cytochromes b-c segment.

    Science.gov (United States)

    Papa, S; Lorusso, M; Izzo, G; Capuano, F

    1981-02-15

    component of the aerobic delta microH+ (the sum of the proton chemical and electrical activities) exerts a pH-dependent constraint on forward electron flow from cytochrome b566 to cytochrome b562. This effect is explained as a consequence of anisotropic location of cytochromes b566 and b562 in the membrane and the pH-dependence of the redox function of these cytochromes. Transmembrane delta pH, on the other hand, exerts control on electron flow from cytochrome b562 to c cytochromes.

  4. Application of flow cytometry to determine differential redistribution of cytochrome c and Smac/DIABLO from mitochondria during cell death signaling.

    Directory of Open Access Journals (Sweden)

    Heling Ng

    Full Text Available Mitochondrially mediated apoptosis is characterized by redistribution of proteins from mitochondria to cytoplasm following permeabilization of the outer mitochondrial membrane. We applied flow cytometry to quantify simultaneously the redistribution of two apoptogenic proteins, cytochrome c (cyt c and Smac/DIABLO (Smac. Mammalian cells were treated with digitonin that selectively permeabilizes the plasma membrane. Following fixation, treated cells were infused successively with primary and secondary antibodies (the latter fluorescently tagged enabling independent detection of cyt c and Smac. Digitonin-treated cells that retain cyt c or Smac in mitochondria generate strong fluorescence signals in flow cytometry. Cells in which cyt c or Smac have transited the outer mitochondrial membrane show greatly reduced fluorescence because the proteins are lost from the digitonin-permeabilized cells. Quantitative flow cytometry revealed that in 143B TK(- cells treated with staurosporine, cyt c and Smac exit mitochondria asymmetrically, with cyt c redistribution preceding that of Smac. However, in HeLa cells likewise treated, cyt c and Smac exit mitochondria concurrently. Under other conditions of apoptotic induction, for example, 143B TK(- cells treated with MT-21 (an apoptotic inducer that binds to the mitochondrial adenine nucleotide transporter, redistribution of Smac precedes that of cyt c. The various patterns of redistribution of these proteins were confirmed by immunocytochemical analysis and confocal microscopy. We conclude that flow cytometry can be employed effectively to quantify simultaneously the redistribution of cyt c and Smac from mitochondria to the cytosol. Moreover, differential redistribution of cyt c and Smac occurs under various conditions, thereby reflecting constraints on availability of these proteins to exit mitochondria after permeabilization of the outer membrane.

  5. Alcohol dehydrogenase and cytochrome P450 2E1 can be induced by long-term exposure to ethanol in cultured liver HEP-G2 cells.

    Science.gov (United States)

    Balusikova, Kamila; Kovar, Jan

    2013-09-01

    It has been shown in previous studies that liver HEP-G2 cells (human hepatocellular carcinoma) lose their ability to express active alcohol dehydrogenase (ADH) and cytochrome P450 2E1 (CYP2E1). Although both are ethanol-inducible enzymes, short-term exposure to ethanol does not cause any changes in expression or activity in cultured HEP-G2 cells. Therefore, we tested the effect of long-term exposure to ethanol on the expression and activity of both ADH and CYP2E1 in these cells. The expression of ADH and CYP2E1 was assessed at the mRNA and/or protein level using real-time PCR and Western blot analysis. Specific colorimetric assays were used for the measurement of ADH and CYP2E1 enzymatic activities. Caco-2 cells (active CYP2E1 and inactive ADH) were used as control cells. Significantly increased protein expression of ADH (about 2.5-fold) as well as CYP2E1 (about 1.6-fold) was found in HEP-G2 cells after long-term (12 mo) exposure to ethanol. The activity of ADH and CYP2E1 was also significantly increased from 12 ± 3 and 6 ± 1 nmol/h/mg of total protein to 191 ± 9 and 57 ± 9 nmol/h/mg of total protein, respectively. We suggest that the loss of activity of ethanol-metabolizing enzymes in cultured HEP-G2 cells is reversible and can be induced by prolonged exposure to ethanol. We are therefore able to reactivate HEP-G2 cells metabolic functions concerning ethanol oxidation just by modification of in vitro culture conditions without necessity of transfection with its side effect - enzyme overexpression.

  6. Label-free photoacoustic microscopy of cytochromes

    Science.gov (United States)

    Zhang, Chi; Zhang, Yu Shrike; Yao, Da-Kang; Xia, Younan; Wang, Lihong V.

    2013-02-01

    Photoacoustic microscopy (PAM) has achieved submicron lateral resolution in showing subcellular structures; however, relatively few endogenous subcellular contrasts have so far been imaged. Given that the hemeprotein, mostly cytochromes in general cells, is optically absorbing around the Soret peak (˜420 nm), we implemented label-free PAM of cytochromes in cytoplasm for the first time. By measuring the photoacoustic spectra of the oxidized and reduced states of fibroblast lysate and fitting the difference spectrum with three types of cytochromes, we found that the three cytochromes account for more than half the optical absorption in the cell lysate at 420 nm wavelength. Fixed fibroblasts on slides were imaged by PAM at 422 and 250 nm wavelengths to reveal cytoplasms and nuclei, respectively, as confirmed by standard staining histology. PAM was also applied to label-free histology of mouse ear sections by showing cytoplasms and nuclei of various cells. PAM of cytochromes in cytoplasm is expected to be a high-throughput, label-free technique for studying live cell functions, which cannot be accomplished by conventional histology.

  7. Cytochrome P450 2A13 enhances the sensitivity of human bronchial epithelial cells to aflatoxin B1-induced DNA damage

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xuejiao [Key Lab of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, 818 East Tiangyuan Rd., Nanjing 211166 (China); Jiaojiang District Center for Disease Control and Prevention, 518 Jingdong Rd., Taizhou 318000 (China); Zhang, Zhan; Wang, Xichen; Wang, Yun; Zhang, Xiaoming; Lu, Huiyuan [Key Lab of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, 818 East Tiangyuan Rd., Nanjing 211166 (China); Wang, Shou-Lin, E-mail: wangshl@njmu.edu.cn [Key Lab of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, 818 East Tiangyuan Rd., Nanjing 211166 (China)

    2013-07-15

    Cytochrome P450 2A13 (CYP2A13) mainly expresses in human respiratory system and mediates the metabolic activation of aflatoxin B1 (AFB1). Our previous study suggested that CYP2A13 could increase the cytotoxic and apoptotic effects of AFB1 in immortalized human bronchial epithelial cells (BEAS-2B). However, the role of CYP2A13 in AFB1-induced DNA damage is unclear. Using BEAS-2B cells that stably express CYP2A13 (B-2A13), CYP1A2 (B-1A2), and CYP2A6 (B-2A6), we compared their effects in AFB1-induced DNA adducts, DNA damage, and cell cycle changes. BEAS-2B cells that were transfected with vector (B-vector) were used as a control. The results showed that AFB1 (5–80 nM) dose- and time-dependently induced DNA damage in B-2A13 cells. AFB1 at 10 and 80 nM significantly augmented this effect in B-2A13 and B-1A2 cells, respectively. B-2A6 cells showed no obvious DNA damage, similar to B-vector cells and the vehicle control. Similarly, compared with B-vector, B-1A2 or B-2A6 cells, B-2A13 cells showed more sensitivity in AFB1-induced γH2AX expression, DNA adduct 8-hydroxy-deoxyguanosine formation, and S-phase cell-cycle arrest. Furthermore, AFB1 activated the proteins related to DNA damage responses, such as ATM, ATR, Chk2, p53, BRCA1, and H2AX, rather than the proteins related to DNA repair. These effects could be almost completely inhibited by 100 μM nicotine (a substrate of CYP2A13) or 1 μM 8-methoxypsoralen (8-MOP; an inhibitor of CYP enzyme). Collectively, these findings suggest that CYP2A13 plays an important role in low-concentration AFB1-induced DNA damage, possibly linking environmental airborne AFB1 to genetic injury in human respiratory system. - Highlights: • CYP2A13 plays a critical role in low concentration of AFB1-induced DNA damage. • B-2A13 cells were more sensitive to AFB1 than B-1A2 cells and B-2A6 cells. • AFB1 dose- and time-dependently induced DNA damage in B-2A13 cells • AFB1-induced DNA adducts and damage can be inhibited by nicotine and 8

  8. Influence of Sulforaphane Metabolites on Activities of Human Drug-Metabolizing Cytochrome P450 and Determination of Sulforaphane in Human Liver Cells.

    Science.gov (United States)

    Vanduchova, Alena; Tomankova, Veronika; Anzenbacher, Pavel; Anzenbacherova, Eva

    2016-12-01

    The influence of metabolites of sulforaphane, natural compounds present in broccoli (Brassica oleracea var. botrytis italica) and in other cruciferous vegetables, on drug-metabolizing cytochrome P450 (CYP) enzymes in human liver microsomes and possible entry of sulforaphane into human hepatic cells were investigated. Metabolites studied are compounds derived from sulforaphane by the mercapturic acid pathway (conjugation with glutathione and by following reactions), namely sulforaphane glutathione and sulforaphane cysteine conjugates and sulforaphane-N-acetylcysteine. Their possible effect on four drug-metabolizing CYP enzymes, CYP3A4 (midazolam 1'-hydroxylation), CYP2D6 (bufuralol 1'-hydroxylation), CYP1A2 (7-ethoxyresorufin O-deethylation), and CYP2B6 (7-ethoxy-4-(trifluoromethyl)coumarin O-deethylation), was tested. Inhibition of four prototypical CYP activities by sulforaphane metabolites was studied in pooled human liver microsomes. Sulforaphane metabolites did not considerably affect biological function of drug-metabolizing CYPs in human liver microsomes except for CYP2D6, which was found to be inhibited down to 73-78% of the original activity. Analysis of the entry of sulforaphane into human hepatocytes was done by cell disruption by sonication, methylene chloride extraction, and modified high-performance liquid chromatography method. The results have shown penetration of sulforaphane into the human hepatic cells.

  9. Intracellular renin disrupts chemical communication between heart cells. Pathophysiological implications

    Directory of Open Access Journals (Sweden)

    Walmor eDe Mello

    2015-01-01

    Full Text Available The influence of intracellular renin on the process of chemical communication between cardiac cells was investigated in cell pairs isolated from the left ventricle of adult Wistar Kyoto rats. The enzyme together with Lucifer yellow CH was dialyzed into one cell of the pair using the whole cell clamp technique. The diffusion of the dye in the dialyzed and in non-dialyzed cell was followed by measuring the intensity of fluorescence in both cells as a function of time. The results indicated that; 1 under normal conditions, Lucifer Yellow flows from cell-to-cell through gap junctions; 2 the intracellular dialysis of renin (100nM disrupts chemical communication-an effect enhanced by simultaneous administration of angiotensinogen (100nM; 3 enalaprilat (10-9M administered to the cytosol together with renin reduced drastically the uncoupling action of the enzyme; 4 aliskiren (10-8M inhibited the effect of renin on chemical communication;5 the possible role of intracellular renin independently of angiotensin II (Ang II was evaluated including the increase of the inward calcium current elicited by the enzyme and the possible role of oxidative stress on the disruption of cell communication; 6 the possible harmful versus the beneficial effect of intracellular renin during myocardial infarction was discussed;7 the present results indicate that intracellular renin due to internalization or in situ synthesis, causes a severe impairment of chemical communication in the heart resulting in derangement of metabolic cooperation with serious consequences for heart function.

  10. Two-Way Chemical Communication between Artificial and Natural Cells

    Science.gov (United States)

    2017-01-01

    Artificial cells capable of both sensing and sending chemical messages to bacteria have yet to be built. Here we show that artificial cells that are able to sense and synthesize quorum signaling molecules can chemically communicate with V. fischeri, V. harveyi, E. coli, and P. aeruginosa. Activity was assessed by fluorescence, luminescence, RT-qPCR, and RNA-seq. Two potential applications for this technology were demonstrated. First, the extent to which artificial cells could imitate natural cells was quantified by a type of cellular Turing test. Artificial cells capable of sensing and in response synthesizing and releasing N-3-(oxohexanoyl)homoserine lactone showed a high degree of likeness to natural V. fischeri under specific test conditions. Second, artificial cells that sensed V. fischeri and in response degraded a quorum signaling molecule of P. aeruginosa (N-(3-oxododecanoyl)homoserine lactone) were constructed, laying the foundation for future technologies that control complex networks of natural cells. PMID:28280778

  11. Two-Way Chemical Communication between Artificial and Natural Cells.

    Science.gov (United States)

    Lentini, Roberta; Martín, Noël Yeh; Forlin, Michele; Belmonte, Luca; Fontana, Jason; Cornella, Michele; Martini, Laura; Tamburini, Sabrina; Bentley, William E; Jousson, Olivier; Mansy, Sheref S

    2017-02-22

    Artificial cells capable of both sensing and sending chemical messages to bacteria have yet to be built. Here we show that artificial cells that are able to sense and synthesize quorum signaling molecules can chemically communicate with V. fischeri, V. harveyi, E. coli, and P. aeruginosa. Activity was assessed by fluorescence, luminescence, RT-qPCR, and RNA-seq. Two potential applications for this technology were demonstrated. First, the extent to which artificial cells could imitate natural cells was quantified by a type of cellular Turing test. Artificial cells capable of sensing and in response synthesizing and releasing N-3-(oxohexanoyl)homoserine lactone showed a high degree of likeness to natural V. fischeri under specific test conditions. Second, artificial cells that sensed V. fischeri and in response degraded a quorum signaling molecule of P. aeruginosa (N-(3-oxododecanoyl)homoserine lactone) were constructed, laying the foundation for future technologies that control complex networks of natural cells.

  12. Metyrapone, an inhibitor of cytochrome oxidases, does not affect viability in a neuroblastoma cell model of bilirubin toxicity

    Directory of Open Access Journals (Sweden)

    Maria N. Naguib Leerberg

    2014-01-01

    Conclusion: Herein we have shown that metyrapone does not increase cell death in neuroblastoma cells in culture exposed to bilirubin. Our results question the relationship between the oxidative mechanism evaluated by spectrophotometry and cell viability. Our findings add to the discussion on whether bilirubin oxidation represents a potentially important protective mechanism in neurons challenged by hyperbilirubinemia.

  13. Chemical -induced apoptotic cell death in tomato cells : involvement of caspase-like proteases

    NARCIS (Netherlands)

    Jong, de A.J.; Hoeberichts, F.A.; Yakimova, E.T.; Maximova, E.; Woltering, E.J.

    2000-01-01

    A new system to study programmed cell death in plants is described. Tomato (Lycopersicon esculentum Mill.) suspension cells were induced to undergo programmed cell death by treatment with known inducers of apoptosis in mammalian cells. This chemical-induced cell death was accompanied by the

  14. Nicotine Component of Cigarette Smoke Extract (CSE) Decreases the Cytotoxicity of CSE in BEAS-2B Cells Stably Expressing Human Cytochrome P450 2A13.

    Science.gov (United States)

    Ji, Minghui; Zhang, Yudong; Li, Na; Wang, Chao; Xia, Rong; Zhang, Zhan; Wang, Shou-Lin

    2017-10-13

    Cytochrome P450 2A13 (CYP2A13), an extrahepatic enzyme mainly expressed in the human respiratory system, has been reported to mediate the metabolism and toxicity of cigarette smoke. We previously found that nicotine inhibited 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) metabolism by CYP2A13, but its influence on other components of cigarette smoke remains unclear. The nicotine component of cigarette smoke extract (CSE) was separated, purified, and identified using high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS), splitting CSE into a nicotine section (CSE-N) and nicotine-free section (CSE-O). Cell viability and apoptosis by Cell Counting Kit-8 (CCK-8) and flow cytometry assays were conducted on immortalized human bronchial epithelial (BEAS-2B) cells stably expressing CYP2A13 (B-2A13) or vector (B-V), respectively. Interestingly, CSE and CSE-O were toxic to BEAS-2B cells whereas CSE-N showed less cytotoxicity. CSE-O was more toxic to B-2A13 cells than to B-V cells (IC 50 of 2.49% vs. 7.06%), which was flatted by 8-methoxypsoralen (8-MOP), a CYP inhibitor. CSE-O rather than CSE or CSE-N increased apoptosis of B-2A13 cells rather than B-V cells. Accordingly, compared to CSE-N and CSE, CSE-O significantly changed the expression of three pairs of pro- and anti-apoptotic proteins, Bcl-2 Associated X Protein/B cell lymphoma-2 (Bax/Bcl-2), Cleaved Poly (Adenosine Diphosphate-Ribose) Polymerase/Poly (Adenosine Diphosphate-Ribose) Polymerase (C-PARP/PARP), and C-caspase-3/caspase-3, in B-2A13 cells. In addition, recombination of CSE-N and CSE-O (CSE-O/N) showed similar cytotoxicity and apoptosis to the original CSE. These results demonstrate that the nicotine component decreases the metabolic activation of CYP2A13 to CSE and aids in understanding the critical role of CYP2A13 in human respiratory diseases caused by cigarette smoking.

  15. Vasoactive intestinal peptide-induced expression of cytochrome P450 cholesterol side-chain cleavage and 17 alpha-hydroxylase enzyme activity in hen granulosa cells.

    Science.gov (United States)

    Johnson, A L; Li, Z; Gibney, J A; Malamed, S

    1994-08-01

    Experiments were conducted to determine whether vasoactive intestinal peptide (VIP) can regulate expression of cytochrome P450 side-chain cleavage (P450scc) and P450 17 alpha-hydroxylase (P450 17 alpha-OH) mRNA levels and enzyme activity in granulosa cells from nonhierarchal (6-8-mm) follicles. Initial studies demonstrated that immunoreactive VIP is localized within the theca (but not granulosa) layer of both resting (< 0.5-mm follicles) and 6-8-mm follicles, thus providing a potential paracrine mechanism of action for VIP. While short-term (3 h) incubation of granulosa cells with VIP (0.001-1.0 microM) failed to stimulate progesterone production from 6-8-mm follicle granulosa cells, a 4-h culture period in the presence of VIP resulted in increased cyclic AMP (cAMP) accumulation, and a 24-h culture period resulted in progesterone synthesis and increased P450scc mRNA levels; control levels of each endpoint measurement were not altered within the period observed. By contrast, culture with the growth factor transforming growth factor alpha (TGF alpha) in the presence of VIP (1 microM) prevented increases in P450scc mRNA levels and progesterone production. Similar effects of VIP and TGF alpha in the presence of VIP were demonstrated for P450 17 alpha-OH mRNA levels and enzyme activity. Finally, there was an additive effect of VIP (0.1 microM) plus recombinant human (rh) FSH (100 mIU) on the initiation of progesterone production in cultured 6-8-mm follicle granulosa cells compared to the addition of VIP or rhFSH alone.(ABSTRACT TRUNCATED AT 250 WORDS)

  16. Chemical Conversion of Human Fibroblasts into Functional Schwann Cells

    Directory of Open Access Journals (Sweden)

    Eva C. Thoma

    2014-10-01

    Full Text Available Direct transdifferentiation of somatic cells is a promising approach to obtain patient-specific cells for numerous applications. However, conversion across germ-layer borders often requires ectopic gene expression with unpredictable side effects. Here, we present a gene-free approach that allows efficient conversion of human fibroblasts via a transient progenitor stage into Schwann cells, the major glial cell type of peripheral nerves. Using a multikinase inhibitor, we transdifferentiated fibroblasts into transient neural precursors that were subsequently further differentiated into Schwann cells. The resulting induced Schwann cells (iSCs expressed numerous Schwann cell-specific proteins and displayed neurosupportive and myelination capacity in vitro. Thus, we established a strategy to obtain mature Schwann cells from human postnatal fibroblasts under chemically defined conditions without the introduction of ectopic genes.

  17. Engineering chemically modified viruses for prostate cancer cell recognition.

    Science.gov (United States)

    Mohan, K; Weiss, G A

    2015-12-01

    Specific detection of circulating tumor cells and characterization of their aggressiveness could improve cancer diagnostics and treatment. Metastasis results from such tumor cells, and causes the majority of cancer deaths. Chemically modified viruses could provide an inexpensive and efficient approach to detect tumor cells and quantitate their cell surface biomarkers. However, non-specific adhesion between the cell surface receptors and the virus surface presents a challenge. This report describes wrapping the virus surface with different PEG architectures, including as fusions to oligolysine, linkers, spacers and scaffolded ligands. The reported PEG wrappers can reduce by >75% the non-specific adhesion of phage to cell surfaces. Dynamic light scattering verified the non-covalent attachment by the reported wrappers as increased sizes of the virus particles. Further modifications resulted in specific detection of prostate cancer cells expressing PSMA, a key prostate cancer biomarker. The approach allowed quantification of PSMA levels on the cell surface, and could distinguish more aggressive forms of the disease.

  18. Mechanistic role of cytochrome P450 (CYP)1B1 in oxygen-mediated toxicity in pulmonary cells: A novel target for prevention of hyperoxic lung injury.

    Science.gov (United States)

    Dinu, Daniela; Chu, Chun; Veith, Alex; Lingappan, Krithika; Couroucli, Xanthi; Jefcoate, Colin R; Sheibani, Nader; Moorthy, Bhagavatula

    2016-08-05

    Supplemental oxygen, which is routinely administered to preterm infants with pulmonary insufficiency, contributes to bronchopulmonary dysplasia (BPD) in these infants. Hyperoxia also contributes to the development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) in adults. The mechanisms of oxygen-mediated pulmonary toxicity are not completely understood. Recent studies have suggested an important role for cytochrome P450 (CYP)1A1/1A2 in the protection against hyperoxic lung injury. The role of CYP1B1 in oxygen-mediated pulmonary toxicity has not been studied. In this investigation, we tested the hypothesis that CYP1B1 plays a mechanistic role in oxygen toxicity in pulmonary cells in vitro. In human bronchial epithelial cell line BEAS-2B, hyperoxic treatment for 1-3 days led to decreased cell viability by about 50-80%. Hyperoxic cytotoxicity was accompanied by an increase in levels of reactive oxygen species (ROS) by up to 110%, and an increase of TUNEL-positive cells by up to 4.8-fold. Western blot analysis showed hyperoxia to significantly down-regulate CYP1B1 protein level. Also, there was a decrease of CYP1B1 mRNA by up to 38% and Cyp1b1 promoter activity by up to 65%. On the other hand, CYP1B1 siRNA appeared to rescue the cell viability under hyperoxia stress, and overexpression of CYP1B1 significantly attenuated hyperoxic cytotoxicity after 48 h of incubation. In immortalized lung endothelial cells derived from Cyp1b1-null and wild-type mice, hyperoxia increased caspase 3/7 activities in a time-dependent manner, but endothelial cells lacking the Cyp1b1 gene showed significantly decreased caspase 3/7 activities after 48 and 72 h of incubation, implying that CYP1B1 might promote apoptosis in wild type lung endothelial cells under hyperoxic stress. In conclusion, our results support the hypothesis that CYP1B1 plays a mechanistic role in pulmonary oxygen toxicity, and CYP1B1-mediated apoptosis could be one of the mechanisms of oxygen

  19. The effect of lycopene on cytochrome P450 isoenzymes and P-glycoprotein by using human liver microsomes and Caco-2 cell monolayer model.

    Science.gov (United States)

    Kong, Lingti; Song, Chunli; Ye, Linhu; Xu, Jian; Guo, Daohua; Shi, Qingping

    2018-01-11

    Lycopene is widely used as a dietary supplement. However, the effects of lycopene on cytochrome P450 (CYP) enzymes or P-glycoprotein (P-gp) are not comprehensive. The present study was performed to investigate the effects of lycopene on the CYP enzymes and P-gp activity. A cocktail method was used to evaluate the activities of CYP3A4, CYP2C9, CYP2C19, CYP2D6 and CYP2E1. Caco-2 cell monolayer model was carried out to assay lycopene on P-gp activity. The results indicated that lycopene had a moderate inhibitory effect on CYP2E1, with IC50 value of 43.65 μM, whereas no inhibitory effects on CYP3A4, CYP2C19, CYP2D6 and CYP2E1, with IC50 values all over 100 μM. In addition, lycopene showed almost no inhibitory effect on rhodamine-123 efflux and uptake (p > .05), indicated no effects on P-gp activity. In conclusion, there should be required attention when lycopene are coadministered with other drugs that are metabolised by CYP2E1.

  20. Induction of human cytochrome P450 3A enzymes in cultured placental cells by thalidomide and relevance to bioactivation and toxicity.

    Science.gov (United States)

    Murayama, Norie; Kazuki, Yasuhiro; Satoh, Daisuke; Arata, Kazuya; Harada, Tasuku; Shibata, Norio; Guengerich, F Peter; Yamazaki, Hiroshi

    2017-01-01

    Evidence has been presented for auto-induced human cytochrome P450 3A enzyme involvement in the teratogenicity and clinical outcome of thalidomide due to oxidation to 5-hydroxythalidomide and subsequent metabolic activation in livers. In this study, more relevant human placenta preparations and placental BeWo cells showed low but detectable P450 3A4/5 mRNA expression and drug oxidation activities. Human placental microsomal fractions from three subjects showed detectable midazolam 1´- and 4-hydroxylation and thalidomide 5-hydroxylation activities. Human placental BeWo cells, cultured in the recommended media, also indicated detectable midazolam 1´- and 4-hydroxylation and thalidomide 5-hydroxylation activities. To reduce any masking effects by endogenous hormones used in the recommended media, induction of P450 3A4/5 mRNA and oxidation activities were measured in placental BeWo cells cultured with a modified medium containing 5% charcoal-stripped fetal bovine serum. Thalidomide significantly induced P450 3A4/5, 2B6, and pregnane X receptor (PXR) mRNA levels 2 to 3-fold, but rifampicin only enhanced P450 3A5 and PXR mRNA under the modified media conditions. Under these modified conditions, thalidomide also significantly induced midazolam 1´-hydroxylation and thalidomide 5-hydroxylaion activities 3-fold but not bupropion hydroxylation activity. Taken together, activation of thalidomide to 5-hydroxythalidomide with autoinduction of P450 3A enzymes in human placentas, as well as livers, is suggested in vivo.

  1. A novel upconversion@polydopamine core@shell nanoparticle based aptameric biosensor for biosensing and imaging of cytochrome c inside living cells.

    Science.gov (United States)

    Ma, Lina; Liu, Fuyao; Lei, Zhen; Wang, Zhenxin

    2017-01-15

    Herein, a novel upconversion@polydopamine core@shell nanoparticle (termed as UCNP@PDA NP) -based aptameric biosensor has been fabricated for the quantitative analysis of cytochrome c (Cyt c) inside living cells, which comprises an UCNP@PDA NP, acting as an internal reference and fluorescence quenching agent, and Cy3 modified aptamer enabling ratiometric quantitative Cyt c measurement. After the hybridization of Cy3 labeled aptamer with amino-terminated single DNA on the UCNP@PDA NP surface (termed as UCNP@PDA@AP), the fluorescence of Cy3 can be efficiently quenched by the PDA shell. With the spontaneous cellular uptake of UCNP@PDA@AP, the Cyt c aptamer dissociates from UCNP@PDA NP surface through formation of aptamer-Cyt c complex, resulting in concomitant activation of the Cy3 fluorescence. High amount of Cyt c leads to high fluorescence emission, enabling direct visualization/measurement of the Cyt c by fluorescence microscopy/spectroscopy. The steady upconversion luminescent (UCL) signals can be employed not only for intracellular imaging, but also as an internal reference for evaluating intracellular Cyt c amount using the ratio of fluorescence intensity of Cy3 with the UCL intensity of UCNP. The UCNP@PDA@AP shows a reasonable detection limit (20nM) and large dynamic range (50nM to 10μM, which covers the literature reported values (1-10μM) for cytosolic Cyt c in apoptotic cells) for detecting Cyt c in buffer with excellent selectivity. In addition, the UCNP@PDA@AP has been successfully used to monitor etoposide induced intracellular releasing of Cyt c, providing the possibility for cell-based screening of apoptosis-inducing drugs. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. One-electron reductive bioactivation of 2,3,5,6-tetramethylbenzoquinone by cytochrome P450

    NARCIS (Netherlands)

    Goeptar, A R; te Koppele, J.M.; van Maanen, M.J.; Zoetemelk, C E; Vermeulen, N P

    1992-01-01

    Bioreductive activation of quinones in mammalian liver has generally been attributed to NADPH-cytochrome P450 reductase. However, in view of the 20-30-fold molar excess of cytochrome P450 over NADPH-cytochrome P450 reductase on the endoplasmic reticulum of the rat liver cell and the capability of

  3. Molecular cloning and characterization of a cytochrome P450 taxoid 9á-hydroxylase in Ginkgo biloba cells.

    Science.gov (United States)

    Zhang, Nan; Han, Zhentai; Sun, Guiling; Hoffman, Angela; Wilson, Iain W; Yang, Yanfang; Gao, Qian; Wu, Jianqiang; Xie, Dan; Dai, Jungui; Qiu, Deyou

    2014-01-17

    Taxol is a well-known effective anticancer compound. Due to the inability to synthesize sufficient quantities of taxol to satisfy commercial demand, a biotechnological approach for a large-scale cell or cell-free system for its production is highly desirable. Several important genes in taxol biosynthesis are currently still unknown and have been shown to be difficult to isolate directly from Taxus, including the gene encoding taxoid 9α-hydroxylase. Ginkgo biloba suspension cells exhibit taxoid hydroxylation activity and provides an alternate means of identifying genes encoding enzymes with taxoid 9α-hydroxylation activity. Through analysis of high throughput RNA sequencing data from G. biloba, we identified two candidate genes with high similarity to Taxus CYP450s. Using in vitro cell-free protein synthesis assays and LC-MS analysis, we show that one candidate that belongs to the CYP716B, a subfamily whose biochemical functions have not been previously studied, possessed 9α-hydroxylation activity. This work will aid future identification of the taxoid 9α-hydroxylase gene from Taxus sp. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. A nucleic acid dependent chemical photocatalysis in live human cells

    DEFF Research Database (Denmark)

    Arian, Dumitru; Cló, Emiliano; Gothelf, Kurt V

    2010-01-01

    Only two nucleic acid directed chemical reactions that are compatible with live cells have been reported to date. Neither of these processes generate toxic species from nontoxic starting materials. Reactions of the latter type could be applied as gene-specific drugs, for example, in the treatment...

  5. Local Circuits of V1 Layer 4B Neurons Projecting to V2 Thick Stripes Define Distinct Cell Classes and Avoid Cytochrome Oxidase Blobs

    Science.gov (United States)

    Yarch, Jeff; Federer, Frederick

    2017-01-01

    Decades of anatomical studies on the primate primary visual cortex (V1) have led to a detailed diagram of V1 intrinsic circuitry, but this diagram lacks information about the output targets of V1 cells. Understanding how V1 local processing relates to downstream processing requires identification of neuronal populations defined by their output targets. In primates, V1 layers (L)2/3 and 4B send segregated projections to distinct cytochrome oxidase (CO) stripes in area V2: neurons in CO blob columns project to thin stripes while neurons outside blob columns project to thick and pale stripes, suggesting functional specialization of V1-to-V2 CO streams. However, the conventional diagram of V1 shows all L4B neurons, regardless of their soma location in blob or interblob columns, as projecting selectively to CO blobs in L2/3, suggesting convergence of blob/interblob information in L2/3 blobs and, possibly, some V2 stripes. However, it is unclear whether all L4B projection neurons show similar local circuitries. Using viral-mediated circuit tracing, we have identified the local circuits of L4B neurons projecting to V2 thick stripes in macaque. Consistent with previous studies, we found the somata of this L4B subpopulation to reside predominantly outside blob columns; however, unlike previous descriptions of local L4B circuits, these cells consistently projected outside CO blob columns in all layers. Thus, the local circuits of these L4B output neurons, just like their extrinsic projections to V2, preserve CO streams. Moreover, the intra-V1 laminar patterns of axonal projections identify two distinct neuron classes within this L4B subpopulation, including a rare novel neuron type, suggestive of two functionally specialized output channels. SIGNIFICANCE STATEMENT Conventional diagrams of primate primary visual cortex (V1) depict neuronal connections within and between different V1 layers, but lack information about the cells' downstream targets. This information is critical

  6. Testing Turing's Theory of Morphogenesis in Chemical Cells

    Science.gov (United States)

    Tompkins, Nathan; Li, Ning; Girabawe, Camille; Heymann, Michael; Ermentrout, G. Bard; Epstein, Irving; Fraden, Seth

    2015-03-01

    Alan Turing's 1952 paper ``The Chemical Basis of Morphogenesis'' described how reaction-diffusion dynamics could create six spatiotemporal patterns including a stationary pattern that could lead to physical morphogenesis (which now bears his name). This stationary ``Turing pattern'' has been observed in continuous media of various chemical systems but never in diffusively coupled discrete reactors as Turing theorized. We have created a system of microfluidically produced chemical compartments containing the Belousov-Zhabotinsky reaction that are designed to fulfill the assumptions of Turing's theoretical system. This system demonstrates all six spatiotemporal patterns that Turing predicted. In particular, we observe the stationary case that bears Turing's name where the cells create a pattern of oxidized and reduced states. As Turing predicted, this chemical heterogeneity gives rise to physical heterogeneity by driving an osmotic flow, swelling the reduced cells and shrinking the oxidized cells. In addition to the six patterns and physical morphogenesis predicted by Turing we observe a seventh pattern of mixed stationary/oscillatory states that is not predicted by Turing. This seventh pattern requires modifying Turing's theory to include slight heterogeneity to match experiments.

  7. Cell Recovery after Combined Action of Ionizing Radiation and Chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Kyu; Roh, Chang Hyun; Ryu, Tae Ho [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of); Komarova, Ludmila N.; Petin, Vladislav G. [Medical Radiological Research Center, Obninsk (Russian Federation)

    2012-05-15

    Damage repair in malignant cells would be problematic in sterilization of microorganisms and treatment of cancer, as well. The inhibition of cell recovery and DNA single and double strand breaks repair by chemicals is expressed both as a deceleration of recovery rate and a lesser extent of recovery. Three possibilities are involved in the inhibition of cell recovery: (1) impairment of the recovery process itself, (2) increased irreversible damage, and (3) simultaneous exert of the two. There have been fee publications regarding these problems. The aim of this study was to determine which of these points are involved in the inhibition of cell recovery. In this study, a quantitative approach describing cell recovery from potentially lethal damage as a decrease in the effective dose was used

  8. Immobilization of whole cells by chemical vapor deposition of silica.

    Science.gov (United States)

    Sizemore, Susan R; Nichols, Robert; Tatum, Randi; Atanassov, Plamen; Johnson, Glenn R; Luckarift, Heather R

    2013-01-01

    Effective entrapment of whole bacterial cells onto solid-phase materials can significantly improve bioprocessing and other biotechnology applications. Cell immobilization allows integration of biocatalysts in a manner that maintains long-term cell viability and typically enhances process output. A wide variety of functionalized materials have been explored for microbial cell immobilization, and specific advantages and limitations were identified. The method described here is a simple, versatile, and scalable one-step process for the chemical vapor deposition of silica to encapsulate and stabilize viable, whole bacterial cells. The immobilized bacterial population is prepared and captured at a predefined physiological state so as to affix bacteria with a selected metabolic or catalytic capability to compatible materials and surfaces. Immobilization of Shewanella oneidensis to carbon electrodes and immobilization of Acinetobacter venetianus to adsorbent mats are described as model systems.

  9. Cannabidiol induces expression of human cytochrome P450 1A1 that is possibly mediated through aryl hydrocarbon receptor signaling in HepG2 cells.

    Science.gov (United States)

    Yamaori, Satoshi; Kinugasa, Yuka; Jiang, Rongrong; Takeda, Shuso; Yamamoto, Ikuo; Watanabe, Kazuhito

    2015-09-01

    We herein investigated the inducibility of cytochrome P450 1A1 (CYP1A1) by Δ(9)-tetrahydrocannabinol, cannabidiol (CBD), and cannabinol, three major phytocannabinoids, using human hepatoma HepG2 cells. The expression of CYP1A1 and the aryl hydrocarbon receptor (AhR) was measured by a quantitative real-time polymerase chain reaction and/or Western blotting. Δ(9)-Tetrahydrocannabinol and CBD concentration-dependently induced the expression of CYP1A1 mRNA, whereas cannabinol showed little or no induction. Among the phytocannabinoids tested, CBD was the most potent inducer of CYP1A1 expression. The induction of CYP1A1 expression by CBD was significantly attenuated by the knockdown of AhR expression with AhR small interfering RNAs. The role of protein tyrosine kinases (PTKs) in the CBD-mediated induction of CYP1A1 was then examined using herbimycin A, a PTK inhibitor. The upregulation of CYP1A1 by CBD was significantly suppressed by herbimycin A as was the induction by omeprazole but not 3-methylcholanthrene. The inducibility of CYP1A1 by CBD-related compounds was examined to clarify the structural requirements for CBD-mediated CYP1A1 induction. Olivetol, which corresponds to the pentylresorcinol moiety of CBD, significantly induced the expression of CYP1A1, whereas d-limonene, CBD-2'-monomethyl ether, and CBD-2',6'-dimethyl ether did not. These results showed that CBD may have induced human CYP1A1 expression through the activation of PTK-dependent AhR signaling, in which two phenolic hydroxyl groups in the pentylresorcinol moiety of CBD may play structurally important roles. Copyright © 2015. Published by Elsevier Inc.

  10. Al-induced root cell wall chemical components differences of wheat ...

    African Journals Online (AJOL)

    Root growth is different in plants with different levels of Al-tolerance under Al stress. Cell wall chemical components of root tip cell are related to root growth. The aim of this study was to explore the relationship between root growth difference and cell wall chemical components. For this purpose, the cell wall chemical ...

  11. Automated Physico-Chemical Cell Model Development through Information Theory

    Energy Technology Data Exchange (ETDEWEB)

    Peter J. Ortoleva

    2005-11-29

    The objective of this project was to develop predictive models of the chemical responses of microbial cells to variations in their surroundings. The application of these models is optimization of environmental remediation and energy-producing biotechnical processes.The principles on which our project is based are as follows: chemical thermodynamics and kinetics; automation of calibration through information theory; integration of multiplex data (e.g. cDNA microarrays, NMR, proteomics), cell modeling, and bifurcation theory to overcome cellular complexity; and the use of multiplex data and information theory to calibrate and run an incomplete model. In this report we review four papers summarizing key findings and a web-enabled, multiple module workflow we have implemented that consists of a set of interoperable systems biology computational modules.

  12. Proton irradiation of stem cells: Radiation damage and chemical radioprotection

    Science.gov (United States)

    Riley, R. C.; Montour, J. L.; Gurney, C. W.

    1972-01-01

    Effects of high energy protons on erythropoietic stem cells and radioprotection by chemicals were investigated in NASA Space Radiation Effects Laboratory. The effects of a parallel beam of 600 MeV protons. The fluence, when converted to dose, were referenced to the synchrocyclotron beam monitors which were then used to administer radiation exposures. Mice were given graded doses to 300 rads to determine dose-response curve. Other mice received saline, AET, or 5-hydroxytryptamine 10 to 15 minutes before exposure.

  13. Chemical inhibition of NAT10 corrects defects of laminopathic cells

    Science.gov (United States)

    Larrieu, Delphine; Britton, Sébastien; Demir, Mukerrem; Rodriguez, Raphaël; Jackson, Stephen P.

    2014-01-01

    Downregulation and mutations of the nuclear-architecture proteins Lamin A and C cause misshapen nuclei and altered chromatin organization associated with cancer and laminopathies, including the premature-aging disease Hutchinson-Gilford progeria syndrome (HGPS). Here, we identified the small molecule “Remodelin” that improved nuclear architecture, chromatin organization and fitness of both human Lamin A/C depleted cells and HGPS-derived patient cells, and decreased markers of DNA damage in these cells. Using a combination of chemical, cellular and genetic approaches, we identified the acetyl-transferase protein NAT10 as the target of Remodelin that mediated nuclear shape rescue in laminopathic cells via microtubule reorganization. These findings provide insights into how NAT10 affects nuclear architecture, and suggest alternative strategies for treating laminopathies and aging. PMID:24786082

  14. Berberine Targets AP-2/hTERT, NF-κB/COX-2, HIF-1α/VEGF and Cytochrome-c/Caspase Signaling to Suppress Human Cancer Cell Growth.

    Directory of Open Access Journals (Sweden)

    Lingyi Fu

    Full Text Available Berberine (BBR, an isoquinoline derivative alkaloid isolated from Chinese herbs, has a long history of uses for the treatment of multiple diseases, including cancers. However, the precise mechanisms of actions of BBR in human lung cancer cells remain unclear. In this study, we investigated the molecular mechanisms by which BBR inhibits cell growth in human non-small-cell lung cancer (NSCLC cells. Treatment with BBR promoted cell morphology change, inhibited cell migration, proliferation and colony formation, and induced cell apoptosis. Further molecular mechanism study showed that BBR simultaneously targeted multiple cell signaling pathways to inhibit NSCLC cell growth. Treatment with BBR inhibited AP-2α and AP-2β expression and abrogated their binding on hTERT promoters, thereby inhibiting hTERT expression. Knockdown of AP-2α and AP-2β by siRNA considerably augmented the BBR-mediated inhibition of cell growth. BBR also suppressed the nuclear translocation of p50/p65 NF-κB proteins and their binding to COX-2 promoter, causing inhibition of COX-2. BBR also downregulated HIF-1α and VEGF expression and inhibited Akt and ERK phosphorylation. Knockdown of HIF-1α by siRNA considerably augmented the BBR-mediated inhibition of cell growth. Moreover, BBR treatment triggered cytochrome-c release from mitochondrial inter-membrane space into cytosol, promoted cleavage of caspase and PARP, and affected expression of BAX and Bcl-2, thereby activating apoptotic pathway. Taken together, these results demonstrated that BBR inhibited NSCLC cell growth by simultaneously targeting AP-2/hTERT, NF-κB/COX-2, HIF-1α/VEGF, PI3K/AKT, Raf/MEK/ERK and cytochrome-c/caspase signaling pathways. Our findings provide new insights into understanding the anticancer mechanisms of BBR in human lung cancer therapy.

  15. Mechanisms and chemical induction of aneuploidy in rodent germ cells

    Energy Technology Data Exchange (ETDEWEB)

    Mailhes, J B; Marchetti, F

    2004-10-15

    The objective of this review is to suggest that the advances being made in our understanding of the molecular events surrounding chromosome segregation in non-mammalian and somatic cell models be considered when designing experiments for studying aneuploidy in mammalian germ cells. Accurate chromosome segregation requires the temporal control and unique interactions among a vast array of proteins and cellular organelles. Abnormal function and temporal disarray among these, and others to be inidentified, biochemical reactions and cellular organelles have the potential for predisposing cells to aneuploidy. Although numerous studies have demonstrated that certain chemicals (mainly those that alter microtubule function) can induce aneuploidy in mammalian germ cells, it seems relevant to point out that such data can be influenced by gender, meiotic stage, and time of cell-fixation post-treatment. Additionally, a consensus has not been reached regarding which of several germ cell aneuploidy assays most accurately reflects the human condition. More recent studies have shown that certain kinase, phosphatase, proteasome, and topoisomerase inhibitors can also induce aneuploidy in rodent germ cells. We suggest that molecular approaches be prudently incorporated into mammalian germ cell aneuploidy research in order to eventually understand the causes and mechanisms of human aneuploidy. Such an enormous undertaking would benefit from collaboration among scientists representing several disciplines.

  16. Expression and characterization of cytochrome c553 from Heliobacterium modesticaldum.

    Science.gov (United States)

    Kashey, Trevor S; Cowgill, John B; McConnell, Michael D; Flores, Marco; Redding, Kevin E

    2014-06-01

    Cytochrome c553 of Heliobacterium modesticaldum is the donor to P800 (+), the primary electron donor of the heliobacterial reaction center (HbRC). It is a membrane-anchored 14-kDa cytochrome that accomplishes electron transfer from the cytochrome bc complex to the HbRC. The petJ gene encoding cyt c 553 was cloned and expressed in Escherichia coli with a hexahistidine tag replacing the lipid attachment site to create a soluble donor that could be made in a preparative scale. The recombinant cytochrome had spectral characteristics typical of a c-type cytochrome, including an asymmetric α-band, and a slightly red-shifted Soret band when reduced. The EPR spectrum of the oxidized protein was characteristic of a low-spin cytochrome. The midpoint potential of the recombinant cytochrome was +217 ± 10 mV. The interaction between soluble recombinant cytochrome c 553 and the HbRC was also studied. Re-reduction of photooxidized P800 (+) was accelerated by addition of reduced cytochrome c 553. The kinetics were characteristic of a bimolecular reaction with a second order rate of 1.53 × 10(4) M(-1) s(-1) at room temperature. The rate manifested a steep temperature dependence, with a calculated activation energy of 91 kJ mol(-1), similar to that of the native protein in Heliobacillus gestii cells. These data demonstrate that the recombinant soluble cytochrome is comparable to the native protein, and likely lacks a discrete electrostatic binding site on the HbRC.

  17. Light-driven cytochrome P450 hydroxylations

    DEFF Research Database (Denmark)

    Jensen, Kenneth; Jensen, Poul Erik; Møller, Birger Lindberg

    2011-01-01

    Plants are light-driven "green" factories able to synthesize more than 200,000 different bioactive natural products, many of which are high-value products used as drugs (e.g., artemisinin, taxol, and thapsigargin). In the formation of natural products, cytochrome P450 (P450) monooxygenases play...... a key role in catalyzing regio- and stereospecific hydroxylations that are often difficult to achieve using the approaches of chemical synthesis. P450-catalyzed monooxygenations are dependent on electron donation typically from NADPH catalyzed by NADPH-cytochrome P450 oxidoreductase (CPR......). The consumption of the costly cofactor NADPH constitutes an economical obstacle for biotechnological in vitro applications of P450s. This bottleneck has been overcome by the design of an in vitro system able to carry out light-driven P450 hydroxylations using photosystem I (PSI) for light harvesting...

  18. Modeling Chemical Interaction Profiles: II. Molecular Docking, Spectral Data-Activity Relationship, and Structure-Activity Relationship Models for Potent and Weak Inhibitors of Cytochrome P450 CYP3A4 Isozyme

    Directory of Open Access Journals (Sweden)

    Eugene Demchuk

    2012-03-01

    Full Text Available Polypharmacy increasingly has become a topic of public health concern, particularly as the U.S. population ages. Drug labels often contain insufficient information to enable the clinician to safely use multiple drugs. Because many of the drugs are bio-transformed by cytochrome P450 (CYP enzymes, inhibition of CYP activity has long been associated with potentially adverse health effects. In an attempt to reduce the uncertainty pertaining to CYP-mediated drug-drug/chemical interactions, an interagency collaborative group developed a consensus approach to prioritizing information concerning CYP inhibition. The consensus involved computational molecular docking, spectral data-activity relationship (SDAR, and structure-activity relationship (SAR models that addressed the clinical potency of CYP inhibition. The models were built upon chemicals that were categorized as either potent or weak inhibitors of the CYP3A4 isozyme. The categorization was carried out using information from clinical trials because currently available in vitro high-throughput screening data were not fully representative of the in vivo potency of inhibition. During categorization it was found that compounds, which break the Lipinski rule of five by molecular weight, were about twice more likely to be inhibitors of CYP3A4 compared to those, which obey the rule. Similarly, among inhibitors that break the rule, potent inhibitors were 2–3 times more frequent. The molecular docking classification relied on logistic regression, by which the docking scores from different docking algorithms, CYP3A4 three-dimensional structures, and binding sites on them were combined in a unified probabilistic model. The SDAR models employed a multiple linear regression approach applied to binned 1D 13C-NMR and 1D 15N-NMR spectral descriptors. Structure-based and physical-chemical descriptors were used as the basis for developing SAR models by the decision forest method. Thirty-three potent inhibitors

  19. Development of Caco-2 cells co-expressing CYP3A4 and NADPH-cytochrome P450 reductase using a human artificial chromosome for the prediction of intestinal extraction ratio of CYP3A4 substrates.

    Science.gov (United States)

    Takenaka, Toru; Kazuki, Kanako; Harada, Naomoto; Kuze, Jiro; Chiba, Masato; Iwao, Takahiro; Matsunaga, Tamihide; Abe, Satoshi; Oshimura, Mitsuo; Kazuki, Yasuhiro

    2017-02-01

    The Caco-2 cells co-expressing cytochrome P450 (CYP) 3A4 and NADPH-cytochrome P450 reductase (CPR) were developed using a human artificial chromosome (HAC) vector. The CYP3A4 and CPR genes were cloned into the HAC vector in CHO cells using the Cre-loxP system, and the microcell-mediated chromosome transfer technique was used to transfer the CYP3A4-CPR-HAC vector to Caco-2 cells. After seeding onto semipermeable culture inserts, the CYP3A4-CPR-HAC/Caco-2 cells were found to form tight monolayers, similar to the parental cells, as demonstrated by the high transepithelial electrical resistance (TEER) value and comparable permeability of non-CYP3A4 substrates between parent and CYP3A4-CPR-HAC/Caco-2 cell monolayers. The metabolic activity of CYP3A4 (midazolam 1'-hydroxylase activity) in the CYP3A4-CPR-HAC/Caco-2 cells was constant from 22 to 35 passages, indicating that HAC vectors conferred sufficient and sustained CYP3A4 activity to CYP3A4-CPR-HAC/Caco-2 cells. The strong relationship between the metabolic extraction ratios (ER) obtained from the CYP3A4-CPR-HAC/Caco-2 cells and calculated intestinal extraction ratios in humans (Eg) from reported intestinal availability (Fg) was found for 17 substrates of CYP3A4 (r2 = 0.84). The present study suggests that the CYP3A4-CPR-HAC/Caco-2 cell monolayer can serve as an in vitro tool that facilitates the prediction of intestinal extraction ratio (or availability) in humans. Copyright © 2016 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

  20. Role of outer membrane c-type cytochromes MtrC and OmcA in Shewanella oneidensis MR-1 cell production, accumulation, and detachment during respiration on hematite.

    Science.gov (United States)

    Mitchell, A C; Peterson, L; Reardon, C L; Reed, S B; Culley, D E; Romine, M R; Geesey, G G

    2012-07-01

    The iron-reducing bacterium Shewanella oneidensis MR-1 has the capacity to contribute to iron cycling over the long term by respiring on crystalline iron oxides such as hematite when poorly crystalline phases are depleted. The ability of outer membrane cytochromes OmcA and MtrC of MR-1 to bind to and transfer electrons to hematite has led to the suggestion that they function as terminal reductases when this mineral is used as a respiratory substrate. Differences in their redox behavior and hematite-binding properties, however, indicate that they play different roles in the electron transfer reaction. Here, we investigated how these differences in cytochrome behavior with respect to hematite affected biofilm development when the mineral served as terminal electron acceptor (TEA). Upon attachment to hematite, cells of the wild-type (WT) strain as well as those of a ΔomcA mutant but not those of a ΔmtrC mutant replicated and accumulated on the mineral surface. The results indicate that MtrC but not OmcA is required for growth when this mineral serves as TEA. While an OmcA deficiency did not impede cell replication and accumulation on hematite prior to achievement of a maximum surface cell density comparable to that established by WT cells, OmcA was required for efficient electron transfer and cell attachment to hematite once maximum surface cell density was achieved. OmcA may therefore play a role in overcoming barriers to electron transfer and cell attachment to hematite imposed by reductive dissolution of the mineral surface from cell respiration associated with achievement of high surface cell densities. © 2012 Blackwell Publishing Ltd.

  1. Sepiapterin Reductase Mediates Chemical Redox Cycling in Lung Epithelial Cells*

    Science.gov (United States)

    Yang, Shaojun; Jan, Yi-Hua; Gray, Joshua P.; Mishin, Vladimir; Heck, Diane E.; Laskin, Debra L.; Laskin, Jeffrey D.

    2013-01-01

    In the lung, chemical redox cycling generates highly toxic reactive oxygen species that can cause alveolar inflammation and damage to the epithelium, as well as fibrosis. In this study, we identified a cytosolic NADPH-dependent redox cycling activity in mouse lung epithelial cells as sepiapterin reductase (SPR), an enzyme important for the biosynthesis of tetrahydrobiopterin. Human SPR was cloned and characterized. In addition to reducing sepiapterin, SPR mediated chemical redox cycling of bipyridinium herbicides and various quinones; this activity was greatest for 1,2-naphthoquinone followed by 9,10-phenanthrenequinone, 1,4-naphthoquinone, menadione, and 2,3-dimethyl-1,4-naphthoquinone. Whereas redox cycling chemicals inhibited sepiapterin reduction, sepiapterin had no effect on redox cycling. Additionally, inhibitors such as dicoumarol, N-acetylserotonin, and indomethacin blocked sepiapterin reduction, with no effect on redox cycling. Non-redox cycling quinones, including benzoquinone and phenylquinone, were competitive inhibitors of sepiapterin reduction but noncompetitive redox cycling inhibitors. Site-directed mutagenesis of the SPR C-terminal substrate-binding site (D257H) completely inhibited sepiapterin reduction but had minimal effects on redox cycling. These data indicate that SPR-mediated reduction of sepiapterin and redox cycling occur by distinct mechanisms. The identification of SPR as a key enzyme mediating chemical redox cycling suggests that it may be important in generating cytotoxic reactive oxygen species in the lung. This activity, together with inhibition of sepiapterin reduction by redox-active chemicals and consequent deficiencies in tetrahydrobiopterin, may contribute to tissue injury. PMID:23640889

  2. Recombinant human albumin supports single cell cloning of CHO cells in chemically defined media.

    Science.gov (United States)

    Zhu, Jiang; Wooh, Jong Wei; Hou, Jeff Jia Cheng; Hughes, Benjamin S; Gray, Peter P; Munro, Trent P

    2012-01-01

    Biologic drugs, such as monoclonal antibodies, are commonly made using mammalian cells in culture. The cell lines used for manufacturing should ideally be clonal, meaning derived from a single cell, which represents a technically challenging process. Fetal bovine serum is often used to support low cell density cultures, however, from a regulatory perspective, it is preferable to avoid animal-derived components to increase process consistency and reduce the risk of contamination from adventitious agents. Chinese hamster ovary (CHO) cells are the most widely used cell line in industry and a large number of serum-free, protein-free, and fully chemically defined growth media are commercially available, although these media alone do not readily support efficient single cell cloning. In this work, we have developed a simple, fully defined, single-cell cloning media, specifically for CHO cells, using commercially available reagents. Our results show that a 1:1 mixture of CD-CHO™ and DMEM/F12 supplemented with 1.5 g/L of recombinant albumin (Albucult®) supports single cell cloning. This formulation can support recovery of single cells in 43% of cultures compared to 62% in the presence of serum. Copyright © 2012 American Institute of Chemical Engineers (AIChE).

  3. Chemical Profiling of the Plant Cell Wall through Raman Microspectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Han, Ju; Singh, Seema; Sun, Lan; Simmons, Blake; Auer, Manfred; Parvin, Bahram

    2010-03-02

    This paper presents a computational framework for chemical pro.ling of the plant cell wall through the Raman spectroscopy. The system enables query of known spectral signatures and clustering of spectral data based on intrinsic properties. As a result, presence and relative concentration of speci.c chemical bonds can be quanti.ed. The primary contribution of this paper is in representation of raman pro.le in terms of .uorescence background and multiscale peak detection at each grid point (voxel). Such a representation allows ef.cient spatial segmentation based on the coupling between high-level salient properties and low-level symbolic representation at each voxel. The high-level salient properties refer to preferred peaks and their attributes for the entire image. The low-level symbolic representations are based on .uorescence background, spectral peak locations, and their attributes. We present results on a corn stover tissue section that is imaged through Raman microscopy, and the results are consistent with the literature. In addition, automatic clustering indicates several distinct layers of the cell walls with different spectral signatures.

  4. Chemically Deposited Thin-Film Solar Cell Materials

    Science.gov (United States)

    Raffaelle, R.; Junek, W.; Gorse, J.; Thompson, T.; Harris, J.; Hehemann, D.; Hepp, A.; Rybicki, G.

    2005-01-01

    We have been working on the development of thin film photovoltaic solar cell materials that can be produced entirely by wet chemical methods on low-cost flexible substrates. P-type copper indium diselenide (CIS) absorber layers have been deposited via electrochemical deposition. Similar techniques have also allowed us to incorporate both Ga and S into the CIS structure, in order to increase its optical bandgap. The ability to deposit similar absorber layers with a variety of bandgaps is essential to our efforts to develop a multi-junction thin-film solar cell. Chemical bath deposition methods were used to deposit a cadmium sulfide (CdS) buffer layers on our CIS-based absorber layers. Window contacts were made to these CdS/CIS junctions by the electrodeposition of zinc oxide (ZnO). Structural and elemental determinations of the individual ZnO, CdS and CIS-based films via transmission spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy and energy dispersive spectroscopy will be presented. The electrical characterization of the resulting devices will be discussed.

  5. Al-induced root cell wall chemical components differences of wheat ...

    African Journals Online (AJOL)

    Jane

    2011-07-13

    Jul 13, 2011 ... Root growth is different in plants with different levels of Al-tolerance under Al stress. Cell wall chemical components of root tip cell are related to root growth. The aim of this study was to explore the relationship between root growth difference and cell wall chemical components. For this purpose, the cell wall ...

  6. NAD(P)H-dependent quinone oxidoreductase 1 (NQO1) and cytochrome P450 oxidoreductase (CYP450OR) differentially regulate menadione-mediated alterations in redox status, survival and metabolism in pancreatic β-cells.

    Science.gov (United States)

    Gray, Joshua P; Karandrea, Shpetim; Burgos, Delaine Zayasbazan; Jaiswal, Anil A; Heart, Emma A

    2016-11-16

    NQO1 (NAD(P)H-quinone oxidoreductase 1) reduces quinones and xenobiotics to less-reactive compounds via 2-electron reduction, one feature responsible for the role of NQO1 in antioxidant defense in several tissues. In contrast, NADPH cytochrome P450 oxidoreductase (CYP450OR), catalyzes the 1-electron reduction of quinones and xenobiotics, resulting in enhanced superoxide formation. However, to date, the roles of NQO1 and CYP450OR in pancreatic β-cell metabolism under basal conditions and oxidant challenge have not been characterized. Using NQO1 inhibition, over-expression and knock out, we have demonstrated that, in addition to protection of β-cells from toxic concentrations of the redox cycling quinone menadione, NQO1 also regulates the basal level of reduced-to-oxidized nucleotides, suggesting other role(s) beside that of an antioxidant enzyme. In contrast, over-expression of NADPH cytochrome P450 oxidoreductase (CYP450OR) resulted in enhanced redox cycling activity and decreased cellular viability, consistent with the enhanced generation of superoxide and H2O2. Basal expression of NQO1 and CYP450OR was comparable in isolated islets and liver. However, NQO1, but not CYP450OR, was strongly induced in β-cells exposed to menadione. NQO1 and CYP450OR exhibited a reciprocal preference for reducing equivalents in β-cells: while CYP450OR preferentially utilized NADPH, NQO1 primarily utilized NADH. Together, these results demonstrate that NQO1 and CYP450OR reciprocally regulate oxidant metabolism in pancreatic β-cells. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  7. Cytochrome P450 from Plants: Platforms for Valuable ...

    African Journals Online (AJOL)

    Cytochrome P450 enzymes are important for biotechnology due to their capacity to modify diverse secondary metabolites that may produce chemicals with pharmacological properties. Most terpenes, flavonoids and alkaloids require P450 catalytic functions to reach their biological activity. In the last ten years, several efforts ...

  8. Chemical degradation mechanisms of membranes for alkaline membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Choe, Yoong-Kee [National Institute of Advanced Industrial Science and Technology, Umezono 1-1-1, Tsukuba (Japan); Henson, Neil J.; Kim, Yu Seung [Los Alamos National Laboratory, Los Alamos, NM (United States)

    2015-12-31

    Chemical degradation mechanisms of membranes for alkaline membrane fuel cells have been investigated using density functional theory (DFT). We have elucidated that the aryl-ether moiety of membranes is one of the weakest site against attack of hydroxide ions. The results of DFT calculations for hydroxide initiated aryl-ether cleavage indicated that the aryl-ether cleavage occurred prior to degradation of cationic functional group. Such a weak nature of the aryl-ether group arises from the electron deficiency of the aryl group as well as the low bond dissociation energy. The DFT results suggests that removal of the aryl-ether group in the membrane should enhance the stability of membranes under alkaline conditions. In fact, an ether fee poly(phenylene) membrane exhibits excellent stability against the attack from hydroxide ions.

  9. Spatiotemporal chemical dynamics in living cells: from information trafficking to cell physiology.

    Science.gov (United States)

    Petty, Howard R

    2006-01-01

    Biological thought in the 20th century was dominated by the study of structures at increasingly minute levels. For biology to advance beyond structural reductionism and contribute its full measure to clinical care, living biological structures must be understood in the context of their collective chemical processes at the relevant chemical time-scales. Using high-speed fluorescence microscopy, we have studied intra- and inter-cellular signaling using shutter speeds ( approximately 100 ns) that remove the effects of wave motion and diffusion from optical images. By collecting a series of such images, stop-action movies of signal trafficking in living cells are created; these have revealed a new level of spatiotemporal chemical organization within cells. Numerous types of chemical waves have been found in living cells expressing a great variety of physical properties. In this article I will review some of these basic findings, discuss these events in the context of information trafficking, and illustrate the potential implications of this work in medicine.

  10. Ethanol induces mouse spermatogenic cell apoptosis in vivo through over-expression of Fas/Fas-L, p53, and caspase-3 along with cytochrome c translocation and glutathione depletion.

    Science.gov (United States)

    Jana, Kuladip; Jana, Narayan; De, Dipak Kumar; Guha, Sujoy Kumar

    2010-09-01

    Although it has been well established that spermatogenic cells undergo apoptosis when treated with ethanol, the molecular mechanisms behind it remain to be investigated. Adult male mice were given intra-peritoneal injection (IP) of ethanol at a dose of 3 g (15%, v/v) per kg body weight per day during the period of 14 days. Testicular androgenesis and apoptotic germ cell death, along with different interrelated proteins expression, were evaluated. Ethanol treatment induced apoptotic spermatogenic cell death with a decrease in the plasma and intra-testicular testosterone concentration. Western blot analysis revealed that repeated ethanol treatment decreased the expression of steroidogenic acute regulatory protein (StAR), 3 beta-hydroxysteroid dehydrogenase (3beta-HSD) and 17 beta-hydroxysteroid dehydrogenase (17beta-HSD); increased the expression of active caspase-3, p53, Fas and Fas-L; and led to up-regulation of Bax/Bcl-2 ratio and translocation of cytochrome c from mitochondria to cytosol in testis. It has also been shown in our study that repeated ethanol treatment led to up-regulation of caspase-3, p53, Fas, Fas-L transcripts; increase in caspase-3 and caspase-8 activities; diminution of 3beta-HSD, 17beta-HSD, and GPx activities; decrease in the mitochondrial membrane potential along with ROS generation and depletion of glutathione pool in the testicular tissue. The present study has indicated that the ethanol treatment induced apoptosis in the mouse testis through the increased expression of Fas/Fas-L and p53, up-regulation of Bax/Bcl-2 ratio, cytosolic translocation of cytochrome c along with caspase-3 activation and glutathione depletion. (c) 2010 Wiley-Liss, Inc.

  11. Elevated glutathione level does not protect against chronic alcohol mediated apoptosis in recombinant human hepatoma cell line VL-17A over-expressing alcohol metabolizing enzymes--alcohol dehydrogenase and Cytochrome P450 2E1.

    Science.gov (United States)

    Chandrasekaran, Karthikeyan; Swaminathan, Kavitha; Kumar, S Mathan; Chatterjee, Suvro; Clemens, Dahn L; Dey, Aparajita

    2011-06-01

    Chronic consumption of alcohol leads to liver injury. Ethanol-inducible Cytochrome P450 2E1 (CYP2E1) plays a critical role in alcohol mediated oxidative stress due to its ability to metabolize ethanol. In the present study, using the recombinant human hepatoma cell line VL-17A that over-expresses the alcohol metabolizing enzymes-alcohol dehydrogenase (ADH) and CYP2E1; and control HepG2 cells, the mechanism and mode of cell death due to chronic ethanol exposure were studied. Untreated VL-17A cells exhibited apoptosis and oxidative stress when compared with untreated HepG2 cells. Chronic alcohol exposure, i.e., 100 mM ethanol treatment for 72 h caused a significant decrease in viability (47%) in VL-17A cells but not in HepG2 cells. Chronic ethanol mediated cell death in VL-17A cells was predominantly apoptotic, with increased oxidative stress as the underlying mechanism. Chronic ethanol exposure of VL-17A cells resulted in 1.1- to 2.5-fold increased levels of ADH and CYP2E1. Interestingly, the level of the antioxidant GSH was found to be 3-fold upregulated in VL-17A cells treated with ethanol, which may be a metabolic adaptation to the persistent and overwhelming oxidative stress. In conclusion, the increased GSH level may not be sufficient enough to protect VL-17A cells from chronic alcohol mediated oxidative stress and resultant apoptosis. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Screening for chemicals that affect hair cell death and survival in the zebrafish lateral line.

    Science.gov (United States)

    Ou, Henry; Simon, Julian A; Rubel, Edwin W; Raible, David W

    2012-06-01

    The zebrafish lateral line is an efficient model system for the evaluation of chemicals that protect and damage hair cells. Located on the surface of the body, lateral line hair cells are accessible for manipulation and visualization. The zebrafish lateral line system allows rapid screens of large chemical libraries, as well as subsequent thorough evaluation of interesting compounds. In this review, we focus on the results of our previous screens and the evolving methodology of our screens for chemicals that protect hair cells, and chemicals that damage hair cells using the zebrafish lateral line. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Kinetic study on the effects of extremely low frequency electromagnetic field on catalase, cytochrome P450 and inducible nitric oxide synthase in human HaCaT and THP-1 cell lines.

    Science.gov (United States)

    Patruno, A; Tabrez, S; Amerio, P; Pesce, M; Vianale, G; Franceschelli, S; Grilli, A; Kamal, M A; Reale, M

    2011-12-01

    Extremely low frequency electromagnetic fields (ELF-EMF) have been found to produce a variety of biological effects. These effects of ELF-EMF depend upon frequency, amplitude, and length of exposure, and are also related to intrinsic susceptibility and responsiveness of different cell types. Although the mechanism of this interaction is still obscure, ELF-EMF can influence cell proliferation, differentiation, cell cycle, apoptosis, DNA replication and protein expression. The aim of this study was to estimate various kinetic constants of catalase, cytochrome P450 and inducible nitric oxide synthase in response to ELF-EMF exposure in human HaCaT and THP-1 cell lines. In order to evaluate the effect of ELF-EMF on the modulation of cellular responses to an inflammatory stimulus, both cell lines were treated with lipopolysaccharide. To the best of our knowledge there is no available report on such type of kinetic study of selected enzymes in response to ELF-EMF in these cell lines. Therefore, the current study may reveal novel mechanism of ELFEMF biological interaction with the enzymological and hormonal systems of living organisms. These new insights may be important for ELF-EMF application particularly for wound healing, tissue regeneration, Parkinson's and Alzheimer's diseases.

  14. Cytochrome c' of Methylococcus capsulatus Bath.

    Science.gov (United States)

    Zahn, J A; Arciero, D M; Hooper, A B; Dispirito, A A

    1996-09-15

    Cytochrome c' was isolated from the obligate methylotroph Methylococcus capsulatus Bath. The native and subunit molecular masses of the cytochrome were 34.9 kDa and 16.2 kDa, respectively, with an isoelectric pH of 7.0. The amino acid composition and N-terminal amino acid sequence were consistent with identification of the protein as a cytochrome c'. The electron paramagnetic resonance spectrum of the monoheme cytochrome indicated the presence of a high spin, S = 5/2, heme center that is diagnostic of cytochromes c'. The optical absorption spectra of ferric or ferrous cytochrome c' were also characteristic of cytochromes c'. The ferrocytochrome bound carbon monoxide and nitric oxide, but not isocyanide, cyanide, or azide. Changes in physical properties due to binding of CO or NO to some other c'-type cytochromes have been interpreted as an indication of dimer dissociation. In the case of cytochrome c' from M. capsulatus Bath, analytical ultracentrifugation of the ferricytochrome, the ferrocytochrome, and the ferrocytochrome-CO complex indicate that the changes induced by binding of CO are conformational and are not consistent with dimer dissociation. EPR spectra show that cytochrome c' was reduced in the presence of hydroxylamine only when in a complex with cytochrome P-460. The value of the midpoint potential, Em 7.0, was -250 mV for cytochrome c' from M. capsulatus Bath, which is well below the range of values reported for other cytochromes c'. The values of midpoint potentials for cytochrome P-460 (Em 7.0 = -300 mV to -380 mV) and cytochrome C555 (Em 7.0 = +175 mV to +195 mV) are less than and greater than, respectively, the value for cytochrome c' and suggest the possibility that the latter may function as an electron shuttle between cytochrome P-460 and cytochrome C555.

  15. Chemical Imaging of the Cell Membrane by NanoSIMS

    Energy Technology Data Exchange (ETDEWEB)

    Weber, P K; Kraft, M L; Frisz, J F; Carpenter, K J; Hutcheon, I D

    2010-02-23

    The existence of lipid microdomains and their role in cell membrane organization are currently topics of great interest and controversy. The cell membrane is composed of a lipid bilayer with embedded proteins that can flow along the two-dimensional surface defined by the membrane. Microdomains, known as lipid rafts, are believed to play a central role in organizing this fluid system, enabling the cell membrane to carry out essential cellular processes, including protein recruitment and signal transduction. Lipid rafts are also implicated in cell invasion by pathogens, as in the case of the HIV. Therefore, understanding the role of lipid rafts in cell membrane organization not only has broad scientific implications, but also has practical implications for medical therapies. One of the major limitations on lipid organization research has been the inability to directly analyze lipid composition without introducing artifacts and at the relevant length-scales of tens to hundreds of nanometers. Fluorescence microscopy is widely used due to its sensitivity and specificity to the labeled species, but only the labeled components can be observed, fluorophores can alter the behavior of the lipids they label, and the length scales relevant to imaging cell membrane domains are between that probed by fluorescence resonance energy transfer (FRET) imaging (<10 nm) and the diffraction limit of light. Topographical features can be imaged on this length scale by atomic force microscopy (AFM), but the chemical composition of the observed structures cannot be determined. Immuno-labeling can be used to study the distribution of membrane proteins at high resolution, but not lipid composition. We are using imaging mass spectrometry by secondary ion mass spectrometry (SIMS) in concert with other high resolution imaging methods to overcome these limitations. The experimental approach of this project is to combine molecule-specific stable isotope labeling with high-resolution SIMS using a

  16. Gamma irradiation of human leukaemic cells HL-60 and MOLT-4 induces decrease in Mcl-1 and Bid, release of cytochrome c, and activation of caspase-8 and caspase-9.

    Science.gov (United States)

    Tichý, Ales; Záskodová, Darina; Pejchal, Jaroslav; Rezácová, Martina; Osterreicher, Jan; Vávrová, Jirina; Cerman, Jaroslav

    2008-06-01

    Apoptosis is significantly controlled by proteins of Bcl-2 (B-cell lymphoma 2) family promoting cell death or maintaining cell survival. We selected two representatives of Bcl-2 family (anti-apoptotic Mcl-1 - myeloid cell line-1 and pro-apoptotic Bid - Bcl-2 homology domain 3 interacting death agonist), cytochrome c (cyt-c), and two initial caspases (-8 and -9) to evaluate their function in ionizing radiation (IR)-induced apoptosis in human leukaemic cell lines diverging in p53 (TP53 tumor suppressor gene) status. A total of 30 microg of proteins of whole-cell lysates or 10 microg of mitochondrial protein fractions were electrophoretically separated and analyzed by Western-blotting. Here we show that in both HL-60 (p53 null) and MOLT-4 (p53 wild type) leukaemic cells the amount of Mcl-1 initially increased after irradiation by sublethal but not by lethal dose and later (when apoptosis occurred) it decreased in a dose-dependent manner. Caspase-8 was cleaved and afterwards the amount of Bid decreased as it was truncated. We also found cyt-c release from the inner mitochondrial membrane space into cytoplasm to be dose-dependent and it was followed by induction of apoptosis. In the p53-null cells caspase-8 was activated prior caspase-9, whereas the cells harboring p53 exhibited a simultaneous activation of both initial caspases. IR induced a decrease in Mcl-1, activation of Bid, caspase-8, and -9, and release of cyt-c. Presented data indicate that both extrinsic and intrinsic apoptosis signalling pathways were activated in HL-60 and MOLT-4 cells upon exposure to IR regardless to the p53 status.

  17. Cyanobacterium sp. host cell and vector for production of chemical compounds in Cyanobacterial cultures

    Energy Technology Data Exchange (ETDEWEB)

    Piven, Irina; Friedrich, Alexandra; Duhring, Ulf; Uliczka, Frank; Baier, Kerstin; Inaba, Masami; Shi, Tuo; Wang, Kui; Enke, Heike; Kramer, Dan

    2016-04-19

    A cyanobacterial host cell, Cyanobacterium sp., that harbors at least one recombinant gene for the production of a chemical compounds is provided, as well as vectors derived from an endogenous plasmid isolated from the cell.

  18. Chemical degradation of fluorosulfonamide fuel cell membrane polymer model compounds

    Science.gov (United States)

    Alsheheri, Jamela M.; Ghassemi, Hossein; Schiraldi, David A.

    2014-12-01

    The durability of a polymer electrolyte fuel cell membrane, along with high proton conductivity and mechanical performance is critical to the success of these energy conversion devices. Extending our work in perfluorinated membrane stability, aromatic trifluoromethyl sulfonamide model compounds were prepared, and their oxidative degradation was examined. The chemical structures for the models were based on mono-, di- and tri-perfluorinated sulfonamide modified phenyl rings. Durability of the model compounds was evaluated by exposure to hydroxyl radicals generated using Fenton reagent and UV irradiation of hydrogen peroxide. LC-MS results for the mono-substituted model compound indicate greater stability to radical oxidation than the di-substituted species; loss of perfluorinated fonamide side chains appears to be an important pathway, along with dimerization and aromatic ring hydroxylation. The tri-substituted model compound also shows loss of side chains, with the mono-substituted compound being a major oxidation product, along with a limited amount of hydroxylation and dimerization of the starting material.

  19. DNA Charge Transport: From Chemical Principles to the Cell

    Science.gov (United States)

    Arnold, Anna R.; Grodick, Michael A.; Barton, Jacqueline K.

    2016-01-01

    The DNA double helix has captured the imagination of many, bringing it to the forefront of biological research. DNA has unique features that extend our interest into areas of chemistry, physics, material science and engineering. Our laboratory has focused on studies of DNA charge transport (CT), wherein charges can efficiently travel long molecular distances through the DNA helix while maintaining an exquisite sensitivity to base pair π-stacking. Because DNA CT chemistry reports on the integrity of the DNA duplex, this property may be exploited to develop electrochemical devices to detect DNA lesions and DNA-binding proteins. Furthermore, studies now indicate that DNA CT may also be used in the cell by, for example, DNA repair proteins, as a cellular diagnostic, in order to scan the genome to localize efficiently to damage sites. In this review, we describe this evolution of DNA CT chemistry from the discovery of fundamental chemical principles to applications in diagnostic strategies and possible roles in biology. PMID:26933744

  20. How chemistry supports cell biology: the chemical toolbox at your service.

    Science.gov (United States)

    Wijdeven, Ruud H; Neefjes, Jacques; Ovaa, Huib

    2014-12-01

    Chemical biology is a young and rapidly developing scientific field. In this field, chemistry is inspired by biology to create various tools to monitor and modulate biochemical and cell biological processes. Chemical contributions such as small-molecule inhibitors and activity-based probes (ABPs) can provide new and unique insights into previously unexplored cellular processes. This review provides an overview of recent breakthroughs in chemical biology that are likely to have a significant impact on cell biology. We also discuss the application of several chemical tools in cell biology research. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. The Role of Cytochromes P450 in Infection

    Directory of Open Access Journals (Sweden)

    Elisavet Stavropoulou

    2018-01-01

    Full Text Available Cytochromes are expressed in many different tissues of the human body. They are found mostly in intestinal and hepatic tissues. Cytochromes P450 (CYPs are enzymes that oxidize substances using iron and are able to metabolize a large variety of xenobiotic substances. CYP enzymes are linked to a wide array of reactions including and O-dealkylation, S-oxidation, epoxidation, and hydroxylation. The activity of the typical P450 cytochrome is influenced by a variety of factors, such as genus, environment, disease state, herbicide, alcohol, and herbal medications. However, diet seems to play a major role. The mechanisms of action of dietary chemicals, macro- and micronutrients on specific CYP isoenzymes have been extensively studied. Dietary modulation has effects upon the metabolism of xenobiotics. Cytochromes harbor intra- or interindividual and intra- or interethnic genetic polymorphisms. Bacteria were shown to express CYP-like genes. The tremendous metabolic activity of the microbiota is associated to its abundant pool of CYP enzymes, which catalyze phase I and II reactions in drug metabolism. Disease states, intestinal disturbances, aging, environmental toxic effects, chemical exposures or nutrition modulate the microbial metabolism of a drug before absorption. A plethora of effects exhibited by most of CYP enzymes can resemble those of proinflammatory cytokines and IFNs. Moreover, they are involved in the initiation and persistence of pathologic pain by directly activating sensory neurons and inflammatory cytokines.

  2. Non-Chemical Distant Cellular Interactions as a potential confounder of Cell Biology Experiments

    Directory of Open Access Journals (Sweden)

    Ashkan eFarhadi

    2014-10-01

    Full Text Available Distant cells can communicate with each other through a variety of methods. Two such methods involve electrical and/or chemical mechanisms. Non-chemical, distant cellular interactions may be another method of communication that cells can use to modify the behavior of other cells that are mechanically separated. Moreover, non-chemical, distant cellular interactions may explain some cases of confounding effects in Cell Biology experiments. In this article, we review non-chemical, distant cellular interactions studies to try to shed light on the mechanisms in this highly unconventional field of cell biology. Despite the existence of several theories that try to explain the mechanism of non-chemical, distant cellular interactions, this phenomenon is still speculative. Among candidate mechanisms, electromagnetic waves appear to have the most experimental support. In this brief article, we try to answer a few key questions that may further clarify this mechanism.

  3. Cytochromes P450 and drug resistance

    NARCIS (Netherlands)

    Doehmer, J.; Goeptar, A R; Vermeulen, N P

    1993-01-01

    Cytochromes P450 are the key enzymes for activating and inactivating many drugs, in particular anticancer drugs. Therefore, individual expression levels of cytochromes P450 may play a crucial role in drug safety and drug efficacy. Overexpression of cytochrome P450 may yield rapid turnover and

  4. Modelling the collective response of heterogeneous cell populations to stationary gradients and chemical signal relay

    Science.gov (United States)

    Pineda, M.; Eftimie, R.

    2017-12-01

    The directed motion of cell aggregates toward a chemical source occurs in many relevant biological processes. Understanding the mechanisms that control this complex behavior is of great relevance for our understanding of developmental biological processes and many diseases. In this paper, we consider a self-propelled particle model for the movement of heterogeneous subpopulations of chemically interacting cells towards an imposed stable chemical gradient. Our simulations show explicitly how self-organisation of cell populations (which could lead to engulfment or complete cell segregation) can arise from the heterogeneity of chemotactic responses alone. This new result complements current theoretical and experimental studies that emphasise the role of differential cell–cell adhesion on self-organisation and spatial structure of cellular aggregates. We also investigate how the speed of individual cell aggregations increases with the chemotactic sensitivity of the cells, and decreases with the number of cells inside the aggregates

  5. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  6. Mechanism of gastroprotection by bismuth subsalicylate against chemically induced oxidative stress in cultured human gastric mucosal cells.

    Science.gov (United States)

    Bagchi, D; McGinn, T R; Ye, X; Balmoori, J; Bagchi, M; Stohs, S J; Kuszynski, C A; Carryl, O R; Mitra, S

    1999-12-01

    Reactive oxygen species (ROS) are implicated in the pathogenesis of chemically induced gastric mucosal injury. We have investigated the effects of ethanol, hydrochloric acid (HCl), and sodium hydroxide (NaOH) on: (1) enhanced production of ROS including superoxide anion and hydroxyl radicals, (2) modulation of intracellular oxidized states by laser scanning confocal microscopy, and (3) DNA fragmentation, indices of oxidative tissue, and DNA damage in a primary culture of normal human gastric mucosal cells (GC), which were isolated and cultured from Helicobacter pylori-negative endoscopic biopsies from human subjects. The induction of ROS and DNA damage in these cells following exposure to ethanol (15%), HCl (150 mM) and NaOH (150 mM) were assessed by cytochrome c reduction (superoxide anion production), HPLC detection for enhanced production of hydroxyl radicals, changes in intracellular oxidized states by laser scanning confocal microscopy, and DNA damage by quantitating DNA fragmentation. Furthermore, the protective ability of bismuth subsalicylate (BSS) was assessed at concentrations of 25, 50, and 100 mg/liter. Incubation of GC with ethanol, HCI, and NaOH increased superoxide anion production by approximately 8.0-, 6.1-and 7.1-fold and increased hydroxyl radical production by 13.3-, 9.6-, and 8.9-fold, respectively, compared to the untreated gastric cells. Incubation of GC with ethanol, HCl, and NaOH increased DNA fragmentation by approximately 6.7-, 4.3-, and 4.8-fold, respectively. Approximately 20.3-, 17.5-, and 13.1-fold increases in fluorescence intensities were observed following incubation of gastric cells with ethanol, HCl, and NaOH, respectively, demonstrating dramatic changes in the intracellular oxidized states of GC following exposure to these necrotizing agents. Preincubation of GC with 25, 50, and 100 mg/liter of BSS decreased ethanol-induced increases in intracellular oxidized states in these cells by 36%, 56%, and 66%, respectively

  7. Chemical Methods to Induce Beta-Cell Proliferation

    Directory of Open Access Journals (Sweden)

    Amedeo Vetere

    2012-01-01

    Full Text Available Pancreatic beta-cell regeneration, for example, by inducing proliferation, remains an important goal in developing effective treatments for diabetes. However, beta cells have mainly been considered quiescent. This “static” view has recently been challenged by observations of relevant physiological conditions in which metabolic stress is compensated by an increase in beta-cell mass. Understanding the molecular mechanisms underlining these process could open the possibility of developing novel small molecules to increase beta-cell mass. Several cellular cell-cycle and signaling proteins provide attractive targets for high throughput screening, and recent advances in cell culture have enabled phenotypic screening for small molecule-induced beta-cell proliferation. We present here an overview of the current trends involving small-molecule approaches to induce beta-cell regeneration by proliferation.

  8. Automation of 3D cell culture using chemically defined hydrogels.

    Science.gov (United States)

    Rimann, Markus; Angres, Brigitte; Patocchi-Tenzer, Isabel; Braum, Susanne; Graf-Hausner, Ursula

    2014-04-01

    Drug development relies on high-throughput screening involving cell-based assays. Most of the assays are still based on cells grown in monolayer rather than in three-dimensional (3D) formats, although cells behave more in vivo-like in 3D. To exemplify the adoption of 3D techniques in drug development, this project investigated the automation of a hydrogel-based 3D cell culture system using a liquid-handling robot. The hydrogel technology used offers high flexibility of gel design due to a modular composition of a polymer network and bioactive components. The cell inert degradation of the gel at the end of the culture period guaranteed the harmless isolation of live cells for further downstream processing. Human colon carcinoma cells HCT-116 were encapsulated and grown in these dextran-based hydrogels, thereby forming 3D multicellular spheroids. Viability and DNA content of the cells were shown to be similar in automated and manually produced hydrogels. Furthermore, cell treatment with toxic Taxol concentrations (100 nM) had the same effect on HCT-116 cell viability in manually and automated hydrogel preparations. Finally, a fully automated dose-response curve with the reference compound Taxol showed the potential of this hydrogel-based 3D cell culture system in advanced drug development.

  9. Molecular dynamics in cytochrome c oxidase Moessbauer spectra deconvolution

    Energy Technology Data Exchange (ETDEWEB)

    Bossis, Fabrizio [Department of Medical Biochemistry, Medical Biology and Medical Physics (DIBIFIM), University of Bari ' Aldo Moro' , Bari (Italy); Palese, Luigi L., E-mail: palese@biochem.uniba.it [Department of Medical Biochemistry, Medical Biology and Medical Physics (DIBIFIM), University of Bari ' Aldo Moro' , Bari (Italy)

    2011-01-07

    Research highlights: {yields} Cytochrome c oxidase molecular dynamics serve to predict Moessbauer lineshape widths. {yields} Half height widths are used in modeling of Lorentzian doublets. {yields} Such spectral deconvolutions are useful in detecting the enzyme intermediates. -- Abstract: In this work low temperature molecular dynamics simulations of cytochrome c oxidase are used to predict an experimentally observable, namely Moessbauer spectra width. Predicted lineshapes are used to model Lorentzian doublets, with which published cytochrome c oxidase Moessbauer spectra were simulated. Molecular dynamics imposed constraints to spectral lineshapes permit to obtain useful information, like the presence of multiple chemical species in the binuclear center of cytochrome c oxidase. Moreover, a benchmark of quality for molecular dynamic simulations can be obtained. Despite the overwhelming importance of dynamics in electron-proton transfer systems, limited work has been devoted to unravel how much realistic are molecular dynamics simulations results. In this work, molecular dynamics based predictions are found to be in good agreement with published experimental spectra, showing that we can confidently rely on actual simulations. Molecular dynamics based deconvolution of Moessbauer spectra will lead to a renewed interest for application of this approach in bioenergetics.

  10. DESIGN, SYNTHESIS, AND APPLICATION OF THE TRIMETHOPRIM-BASED CHEMICAL TAG FOR LIVE CELL IMAGING

    Science.gov (United States)

    Jing, Chaoran; Cornish, Virginia W.

    2013-01-01

    Over the past decade chemical tags have been developed to complement the use of fluorescent proteins in live cell imaging. Chemical tags retain the specificity of protein labeling achieved with fluorescent proteins through genetic encoding, but provide smaller, more robust tags and modular use of organic fluorophores with high photon-output and tailored functionalities. The trimethoprim-based chemical tag (TMP-tag) was initially developed based on the high affinity interaction between E.coli dihydrofolatereductase and the antibiotic trimethoprim and subsequently rendered covalent and fluorogenic via proximity-induced protein labeling reactions. To date, the TMP-tag is one of the few chemical tags that enable intracellular protein labeling and high-resolution live cell imaging. Here we describe the general design, chemical synthesis, and application of TMP-tag for live cell imaging. Alternative protocols for synthesizing and using the covalent and the fluorogenic TMP-tags are also included. PMID:23839994

  11. Reverse engineering life: physical and chemical mimetics for controlled stem cell differentiation into cardiomyocytes.

    Science.gov (United States)

    Skuse, Gary R; Lamkin-Kennard, Kathleen A

    2013-01-01

    Our ability to manipulate stem cells in order to induce differentiation along a desired developmental pathway has improved immeasurably in recent years. That is in part because we have a better understanding of the intracellular and extracellular signals that regulate differentiation. However, there has also been a realization that stem cell differentiation is not regulated only by chemical signals but also by the physical milieu in which a particular stem cell exists. In this regard we are challenged to mimic both chemical and physical environments. Herein we describe a method to induce stem cell differentiation into cardiomyocytes using a combination of chemical and physical cues. This method can be applied to produce differentiated cells for research and potentially for cell-based therapy of cardiomyopathies.

  12. PARTITIONING OF GADOLINIUM IN THE CHEMICAL PROCESSING CELL

    Energy Technology Data Exchange (ETDEWEB)

    Reboul, S.; Best, D.; Stone, M.; Click, D.

    2011-04-27

    A combination of short-term beaker tests and longer-duration Sludge Receipt and Adjustment Tank (SRAT) simulations were performed to investigate the relative partitioning behaviors of gadolinium and iron under conditions applicable to the Chemical Processing Cell (CPC). The testing was performed utilizing non-radioactive simple Fe-Gd slurries, non-radioactive Sludge Batch 6 simulant slurries, and a radioactive real-waste slurry representative of Sludge Batch 7 material. The testing focused on the following range of conditions: (a) Fe:Gd ratios of 25-100; (b) pH values of 2-6; (c) acidification via addition of nitric, formic, and glycolic acids; (d) temperatures of {approx}93 C and {approx}22 C; and (e) oxalate concentrations of <100 mg/kg and {approx}10,000 mg/kg. The purpose of the testing was to provide data for assessing the potential use of gadolinium as a supplemental neutron poison when dispositioning excess plutonium. Understanding of the partitioning behavior of gadolinium in the CPC was the first step in assessing gadolinium's potential applicability. Significant fractions of gadolinium partitioned to the liquid-phase at pH values of 4.0 and below, regardless of the Fe:Gd ratio. In SRAT simulations targeting nitric and formic acid additions of 150% acid stoichiometry, the pH dropped to a minimum of 3.5-4.0, and the maximum fractions of gadolinium and iron partitioning to solution were both {approx}20%. In contrast, in a SRAT simulation utilizing a nitric and formic acid addition under atypical conditions (due to an anomalously low insoluble solids content), the pH dropped to a minimum of 3.7, and the maximum fractions of gadolinium and iron partitioning to solution were {approx}60% and {approx}70%, respectively. When glycolic acid was used in combination with nitric and formic acids at 100% acid stoichiometry, the pH dropped to a minimum of 3.6-4.0, and the maximum fractions of gadolinium and iron partitioning to solution were 60-80% and 3

  13. Constitutive and inducible expression of cytochromes P4501A (CYP1A1 and CYP1A2) in normal prostate and prostate cancer cells.

    Science.gov (United States)

    Sterling, Kenneth M; Cutroneo, Kenneth R

    2004-02-01

    Constitutive and benzo[a]pyrene (B[a]P) inducible expression of CYP1A1 and CYP1A2 in prostate cancer and normal prostate epithelial cells were examined by immunoblotting. Androgen independent prostate cancer cell lines DU145 and PC3 have constitutive expression of CYP1A and CYP1A1 and CYP1A2, respectively. Four micromolar B[a]P did not appear to induce CYP1A1 or CYP1A2 expression in DU145 or PC3 cells. The androgen dependent prostate cancer cell line, LnCap, also has constitutive expression of CYP1A1 and CYP1A2. However, both CYP1A1 and CYP1A2 are induced by treatment of LnCap cells with 4 microM B[a]P. Untreated normal prostate and primary prostate tumor cells have no detectable CYP1A1 expression. Treatment with 4 microM B[a]P induced CYP1A1 expression in both normal and primary tumor prostate cells. Constitutive CYP1A2 expression was detected in normal prostate cells with little or no induction by exposure to 4 microM B[a]P. Primary prostate tumor cells did not show constitutive expression of CYP1A2. However, CYP1A2 was induced by 4 microM B[a]P in primary prostate tumor cells. These observations indicate that hormonal and cancer specific factors affect the expression and induction of the phase I metabolic enzymes, CYP1A1 and CYP1A2 in prostate cells. These observations may be related to the potential smoking-linked higher risk of prostate cancer development and morbidity of prostate cancer patients who smoke. Copyright 2003 Wiley-Liss, Inc.

  14. Evaluation of 309 environmental chemicals using a mouse embryonic stem cell adherent cell differentiation and cytotoxicity assay.

    Science.gov (United States)

    Chandler, Kelly J; Barrier, Marianne; Jeffay, Susan; Nichols, Harriette P; Kleinstreuer, Nicole C; Singh, Amar V; Reif, David M; Sipes, Nisha S; Judson, Richard S; Dix, David J; Kavlock, Robert; Hunter, Edward S; Knudsen, Thomas B

    2011-01-01

    The vast landscape of environmental chemicals has motivated the need for alternative methods to traditional whole-animal bioassays in toxicity testing. Embryonic stem (ES) cells provide an in vitro model of embryonic development and an alternative method for assessing developmental toxicity. Here, we evaluated 309 environmental chemicals, mostly food-use pesticides, from the ToxCast™ chemical library using a mouse ES cell platform. ES cells were cultured in the absence of pluripotency factors to promote spontaneous differentiation and in the presence of DMSO-solubilized chemicals at different concentrations to test the effects of exposure on differentiation and cytotoxicity. Cardiomyocyte differentiation (α,β myosin heavy chain; MYH6/MYH7) and cytotoxicity (DRAQ5™/Sapphire700™) were measured by In-Cell Western™ analysis. Half-maximal activity concentration (AC₅₀) values for differentiation and cytotoxicity endpoints were determined, with 18% of the chemical library showing significant activity on either endpoint. Mining these effects against the ToxCast Phase I assays (∼500) revealed significant associations for a subset of chemicals (26) that perturbed transcription-based activities and impaired ES cell differentiation. Increased transcriptional activity of several critical developmental genes including BMPR2, PAX6 and OCT1 were strongly associated with decreased ES cell differentiation. Multiple genes involved in reactive oxygen species signaling pathways (NRF2, ABCG2, GSTA2, HIF1A) were strongly associated with decreased ES cell differentiation as well. A multivariate model built from these data revealed alterations in ABCG2 transporter was a strong predictor of impaired ES cell differentiation. Taken together, these results provide an initial characterization of metabolic and regulatory pathways by which some environmental chemicals may act to disrupt ES cell growth and differentiation.

  15. Evaluation of 309 environmental chemicals using a mouse embryonic stem cell adherent cell differentiation and cytotoxicity assay.

    Directory of Open Access Journals (Sweden)

    Kelly J Chandler

    Full Text Available The vast landscape of environmental chemicals has motivated the need for alternative methods to traditional whole-animal bioassays in toxicity testing. Embryonic stem (ES cells provide an in vitro model of embryonic development and an alternative method for assessing developmental toxicity. Here, we evaluated 309 environmental chemicals, mostly food-use pesticides, from the ToxCast™ chemical library using a mouse ES cell platform. ES cells were cultured in the absence of pluripotency factors to promote spontaneous differentiation and in the presence of DMSO-solubilized chemicals at different concentrations to test the effects of exposure on differentiation and cytotoxicity. Cardiomyocyte differentiation (α,β myosin heavy chain; MYH6/MYH7 and cytotoxicity (DRAQ5™/Sapphire700™ were measured by In-Cell Western™ analysis. Half-maximal activity concentration (AC₅₀ values for differentiation and cytotoxicity endpoints were determined, with 18% of the chemical library showing significant activity on either endpoint. Mining these effects against the ToxCast Phase I assays (∼500 revealed significant associations for a subset of chemicals (26 that perturbed transcription-based activities and impaired ES cell differentiation. Increased transcriptional activity of several critical developmental genes including BMPR2, PAX6 and OCT1 were strongly associated with decreased ES cell differentiation. Multiple genes involved in reactive oxygen species signaling pathways (NRF2, ABCG2, GSTA2, HIF1A were strongly associated with decreased ES cell differentiation as well. A multivariate model built from these data revealed alterations in ABCG2 transporter was a strong predictor of impaired ES cell differentiation. Taken together, these results provide an initial characterization of metabolic and regulatory pathways by which some environmental chemicals may act to disrupt ES cell growth and differentiation.

  16. Cell patterning without chemical surface modification: Cell cell interactions between printed bovine aortic endothelial cells (BAEC) on a homogeneous cell-adherent hydrogel

    Science.gov (United States)

    Chen, C. Y.; Barron, J. A.; Ringeisen, B. R.

    2006-10-01

    Cell printing offers the unique ability to directly deposit one or multiple cell types directly onto a surface without the need to chemically pre-treat the surface with lithographic methods. We utilize biological laser printing (BioLP ™) to form patterns of bovine aortic endothelial cells (BAECs) onto a homogeneous cell adherent hydrogel surface. These normal cells are shown to retain near-100% viability post-printing. In order to determine whether BAECs encountered shear and/or heat stress during printing, immunocytochemical staining experiments were performed to detect potential expression of heat shock proteins (HSP) by the deposited cells. Printed BAECs expressed HSP at levels similar to negative control cells, indicating that the BioLP process does not expose cells to damaging levels of stress. However, HSP expression was slightly higher at the highest laser energy studied, suggesting more stress was present under these extreme conditions. Printed BAECs also showed preferential asymmetric growth and migration towards each other and away from the originally printed pattern, demonstrating a retained ability for the cells to communicate post-printing.

  17. Chemical bath process for highly efficient Cd-free chalcopyrite thin-film-based solar cells

    National Research Council Canada - National Science Library

    Ennaoui, A

    1999-01-01

      The highest efficiency for Cu(Ga,In)Se2 (CIGS) thin-film-based solar cells has been achieved with CdS buffer layers prepared by a solution growth method known as the chemical bath deposition (CBD...

  18. Redox Disrupting Potential of ToxCast™Chemicals Ranked by Activity in Mouse Embryonic Stem Cells

    Science.gov (United States)

    Little is known regarding the adverse outcome pathways responsible for developmental toxicity following exposure to chemicals. An evaluation of Toxoast™ Phase I chemicals in an adherent mouse embryonic stem cell (mESC) assay revealed a redox sensitive pathway that correlated with...

  19. REDOX DISRUPTING POTENTIAL OF TOXCAST CHEMICALS RANKED BY ACTIVITY IN MOUSE EMBRYONIC STEM CELLS

    Science.gov (United States)

    To gain insight regarding the adverse outcome pathways leading to developmental toxicity following exposure to chemicals, we evaluated ToxCast™ Phase I chemicals in an adherent mouse embryonic stem cell (mESC) assay and identified a redox sensitive pathway that correlated with al...

  20. Chemical evaluation of non-woven nylon separators used in Ni/Cd cells

    Science.gov (United States)

    Cuddihy, Edward F.

    1991-01-01

    The goals of the chemical analysis was to identify Gates 2505 degradation mechanism, to determine if Eagle-Pitcher 2505 supply suitable for flight, and to assess the 2538 as a candidate replacement, based on chemical findings. Chemical testing strongly indicates that the Gates 2505 stored in Florida had undergone partial chemical deterioration, believed caused by exposure to high humidities and temperature. A suspected role of zinc chloride as a separator concern during storage was not verified in this study (the effect of ZnCl2 on cell/electrode performance was not addressed). No substantial chemical issues or concerns with using EP 2505 as Ni/Cd battery separator for Mars Observer and TOPEX could be found. No chemical issues or concerns with using 2538 as Ni/Cd battery separator were found, in fact, chemical evidence suggest that 2538 may be a better material, as compared to 2505.

  1. Chemical and Enzymatic Strategies for Bacterial and Mammalian Cell Surface Engineering.

    Science.gov (United States)

    Bi, Xiaobao; Yin, Juan; Chen Guanbang, Ashley; Liu, Chuan-Fa

    2018-01-17

    Cell surface serves important functions such as the regulation of cell-cell and cell-environment interactions. The understanding and manipulation of the cell surface is important for a wide range of fundamental studies of cellular behavior and for biotechnological and medical applications. With the rapid advance of biology, chemistry and materials science, many strategies have been developed for the functionalization of bacterial and mammalian cell surfaces. Here, we review the recent development of chemical and enzymatic approaches to cell surface engineering with particular emphasis on discussing the advantages and limitations of each of these strategies. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Influence of chemical inhibitors on cell recovery after exposure to different LET radiation

    Energy Technology Data Exchange (ETDEWEB)

    Evstratova, Ekaterina S.; Petin, Vladislav G. [Medical Radiological Research Center, Obninsk (Russian Federation); Kim, Jin Kyu; KIm, Jin Hong [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2016-12-15

    Chemical radiosensitizers are often used to increase cell radiosensitivity. It is known that the ability of chemical drugs to increase cell radiosensitivity is related with inhibition of cell recovery from damage induced by ionizing radiation. However, there are little comparative investigations of cell sensitivity modification after exposure to radiation with high linear energy transfer (LET). Therefore, we studied the anticancer drugs cisplatin and endoxan and their impact on the ability of yeast cells to recover after cell exposure to radiations with different LET. The ability of cell recovery from radiation damage was less effective after exposure to high-LET radiation, when cells were irradiated without drug, with the increase in cisplatin concentration resulting in the disappearance of this difference. The increase of cisplatin concentration results in progressive increase in the fraction of irreversible damage independently of radiation quality.

  3. Purification and characterization of a cytochrome c with novel caspase-3 activation activity from the pathogenic fungus Rhizopus arrhizus.

    Science.gov (United States)

    Saxena, Manoj; Sharma, Rohit Kumar; Ramirez-Paz, Josell; Tinoco, Arthur D; Griebenow, Kai

    2015-09-03

    Members of Rhizopus species are the most common cause of mucormycosis, a rare but often fatal fungal infection. Host induced pathogen apoptosis and pathogen induced host cell apoptosis are often involved in fungal infections. In many organisms, the release of mitochondrial cytochrome c can trigger apoptosis by activating caspase proteases, but the role of fungal cytochrome c in apoptosis remains unknown. DNA sequence encoding Rhizopus arrhizus cytochrome c was cloned and expressed in E. coli. Both native and recombinant cytochrome c were purified using ion exchange followed by gel filtration chromatography. The identities of purified proteins were confirmed by MALDI-MS and UV-Visible spectroscopy. For the first time, we demonstrated that Rhizopus arrhizus cytochrome c could activate human capspase-3 in HeLa cell extracts. We also found that Rhizopus arrhizus cytochrome c has redox potential, peroxidase activity, and spectral properties similar to human and horse cytochrome c proteins. Rhizopus arrhizus cytochrome c can activate human caspase-3 in HeLa cell extracts and it possesses similar physical and spectral properties as human and horse cytochrome c. This protein was found to have a previously unknown potential to activate human caspase-3, an important step in the apoptosis cascade.

  4. Determination of the molecular weight distribution of non-enzymatic browning products formed by roasting of glucose and glycine and studies on their effects on NADPH-cytochrome c-reductase and glutathione-S-transferase in Caco-2 cells.

    Science.gov (United States)

    Hofmann, T; Ames, J; Krome, K; Faist, V

    2001-06-01

    After thermal treatment of a mixture of glucose and glycine for 2 h at 125 degrees C, about 60% of the starting material was converted into non-soluble, black pigments, whereas 40% of the mixture was still water-soluble. Dialysis of the latter fraction revealed 30.4% of low molecular weight compounds (LMWs; MW or = 10,000 Da). The water-soluble Maillard reaction products (MRPs) were separated by gel permeation chromatography and ultrafiltration, revealing that 60% of the water-soluble products of the total carbohydrate/amino acid mixture had MWs 30,000 Da, amongst which 14.5% showed MWs > 100,000 Da, thus indicating an oligomerisation of LMWs to melanoidins under roasting conditions. To investigate the physiological effects of these MRPs, xenobiotic enzyme activities were analysed in intestinal Caco-2 cells. For Phase-I NADPH-cytochrome c-reductase, the activity in the presence of the LMW and HMW fraction was decreased by 13% and 22%, respectively. Phase-II glutathione-S-transferase activity decreased by 15% and 18%, respectively, after incubation with the LMW and the HMW fractions. Considering the different yields, 30% and 10%, respectively, of the LMW and the HMW fractions, the total amount of the LMW fraction present in the glucose-glycine mixture is more active in modulating these enzyme activities than that of the HMW fraction.

  5. Cytochrome P4501A induction, benzo[a]pyrene metabolism, and nucleotide adduct formation in fish hepatoma cells: Effect of preexposure to 3,3',4,4',5-pentachlorobiphenyl

    Science.gov (United States)

    Smeets, J.M.W.; Voormolen, A.; Tillitt, D.E.; Everaarts, J.M.; Seinen, W.; Vanden Berg, M.D.

    1999-01-01

    In PLHC-1 hepatoma cells, benzo[a]pyrene (B[a]P) caused a maximum induction of cytochrome P4501A (CYP1A) activity, measured as ethoxyresorufin O-deethylation (EROD), after 4 to 8 h of exposure, depending on the B[a]P concentration. The decline of EROD activity at longer exposure times was probably caused by the rapid metabolism of B[a]P in this system (57% metabolism within 4 h incubation). In subsequent experiments, PLHC-1 cells were preinduced with PCB 126 for 24 h and then received a dose of 10, 100, or 1,000 nM 3H-B[a]P. A 1-nM concentration of PCB 126 caused an 80-fold induction of CYP1A activity, resulting in an increase in B[a]P metabolism of less than 10%, except at the highest concentration of B[a]P (1,000 nM), where a 50% increase was observed. In another experiment, an 80-fold induction of CYP1A activity caused a 20% increase in the metabolism of B[a]P (100 nM), and RNA adduct formation was increased approximately twofold. These results indicate that, at exposure concentrations up to 100 nM B[a]P, CYP1A activity is not rate limiting for B[a]P metabolism. Furthermore, CYP1A seems to also he specifically involved in B[a]P activation in PLHC-1 cells. However, CYP1A induction causes only a relatively small increase in activation, probably because of the action of other enzymes involved in B[a]P activation and deactivation.

  6. Label-free surface-enhanced infrared spectro-electro-chemical analysis of the Redox potential shift of cytochrome c complexed with a cardiolipin-containing lipid membrane of varied composition

    Science.gov (United States)

    Liu, Li; Wu, Lie; Zeng, Li; Jiang, Xiu-E.

    2015-12-01

    In this study, a lipid membrane was fabricated by fusing cardiolipin-phosphatidylcholine (CL_PC, 1:4) vesicles onto a hydrophobic surface of 1-dodecanethiol (DT) preadsorbed on a nanostructured gold film. By changing the concentration of the DT adsorption solution, we constructed a series of CL_PC-DT bilayers with different hydrophobicity to study the effects of lipid membrane characteristics on the adsorption conformation of cytochrome c (Cyt c). Electrochemical analysis showed that the formal potential is 0.24 V for Cyt c-CL_PC-DT(10), 0.2 V for Cyt c-CL_PC-DT(20), and 0.16 V for Cyt c-CL_PC-DT(40) — a gradual positive shift with the decreasing DT concentration — relative to the potential of native cyt c (0.02 V). Potential-induced surface-enhanced infrared adsorption difference spectroscopy revealed that the gradual positive shift of the formal potential of CL-bound cyt c is determined by the environment with the gradually lowered dielectric constant for the heme cofactor in CL-bound cyt c (Fe3+). Project supported by the National Natural Science Foundation of China (Grant Nos. 91227114, 21322510, and 21105097), the China Postdoctoral Science Foundation (Grant No. 2013M530998), the Natural Science Foundation of Jilin Province, China (Grant No. 201215092), and the President Funds of the Chinese Academy of Sciences.

  7. BEHAVIOR OF MERCURY DURING DWPF CHEMICAL PROCESS CELL PROCESSING

    Energy Technology Data Exchange (ETDEWEB)

    Zamecnik, J.; Koopman, D.

    2012-04-09

    The Defense Waste Processing Facility has experienced significant issues with the stripping and recovery of mercury in the Chemical Processing Cell (CPC). The stripping rate has been inconsistent, often resulting in extended processing times to remove mercury to the required endpoint concentration. The recovery of mercury in the Mercury Water Wash Tank has never been high, and has decreased significantly since the Mercury Water Wash Tank was replaced after the seventh batch of Sludge Batch 5. Since this time, essentially no recovery of mercury has been seen. Pertinent literature was reviewed, previous lab-scale data on mercury stripping and recovery was examined, and new lab-scale CPC Sludge Receipt and Adjustment Tank (SRAT) runs were conducted. For previous lab-scale data, many of the runs with sufficient mercury recovery data were examined to determine what factors affect the stripping and recovery of mercury and to improve closure of the mercury material balance. Ten new lab-scale SRAT runs (HG runs) were performed to examine the effects of acid stoichiometry, sludge solids concentration, antifoam concentration, form of mercury added to simulant, presence of a SRAT heel, operation of the SRAT condenser at higher than prototypic temperature, varying noble metals from none to very high concentrations, and higher agitation rate. Data from simulant runs from SB6, SB7a, glycolic/formic, and the HG tests showed that a significant amount of Hg metal was found on the vessel bottom at the end of tests. Material balance closure improved from 12-71% to 48-93% when this segregated Hg was considered. The amount of Hg segregated as elemental Hg on the vessel bottom was 4-77% of the amount added. The highest recovery of mercury in the offgas system generally correlated with the highest retention of Hg in the slurry. Low retention in the slurry (high segregation on the vessel bottom) resulted in low recovery in the offgas system. High agitation rates appear to result in lower

  8. Diffusion Based Chemical Extraction from Cell Suspensions in Microchannels

    Science.gov (United States)

    Longmire, Ellen; Mata, Clara; Fleming, Katie; Hubel, Allison

    2007-11-01

    Diffusion-based extraction of the cryoprotective agent dimethyl sulfoxide (DMSO) from blood suspensions offers distinct advantages over centrifugation, the conventional method of DMSO removal, most importantly, potential reductions in cell losses. To demonstrate diffusion-based extraction, laminar flows of two parallel streams, a cell suspension containing DMSO and a wash stream, were characterized experimentally. The streams entered a rectangular channel (500 μm x 25 mm x 125 mm) through opposing ports, and the transport of DMSO across the depth was studied as a function of cell suspension flow rate fraction and Peclet number (Pe). Visualization and concentration measurements were performed in the range 1000 < Pe < 10000 (1 < Re < 10). Measured concentration values in the outlet cell and wash streams matched closely with predictions from continuum simulations. Further, for appropriate suspension flow rates and flow rate fractions, cell recovery rates were very high, ˜95%. The results suggest that diffusion methods are viable for processing of clinical-scale suspension volumes.

  9. Cytochrome C oxidase activity and oxygen tolerance.

    Science.gov (United States)

    Campian, Jian Li; Gao, Xueshan; Qian, Mingwei; Eaton, John W

    2007-04-27

    Most cultured cells and intact animals die under hyperoxic conditions. However, a strain of HeLa cells that proliferates under 80% O(2), termed "HeLa-80," has been derived from wildtype HeLa cells ("HeLa-20") by selection for resistance to stepwise increases of oxygen partial pressure. The tolerance of HeLa-80 cells to hyperoxia is not associated with changes in antioxidant defenses or susceptibility to oxidant-mediated killing. Rather, under both 20 and 80% O(2), mitochondrial reactive oxygen species (ROS) production is approximately 2-fold less in HeLa-80 cells, likely related to a significantly higher cytochrome c oxidase (COX) activity ( approximately 2-fold), which may act to deplete upstream electron-rich intermediates responsible for ROS generation. We now report that in HeLa-80 cells elevated COX activity is associated with a >2-fold increase in the regulatory subunit COX Vb, whereas expression levels of other subunits are very close to wild type. Small interfering RNA against Vb selectively lowers COX Vb expression in HeLa-80 cells, increases mitochondrial ROS generation, decreases COX activity 60-80%, and diminishes viability under 80% (but not 20%) O(2). In addition, overexpression of subunit Vb increases COX activity and decreases ROS production in wild-type HeLa-20 cells, along with some increase in tolerance to hyperoxia. Overall, our results indicate that it is possible to make cells tolerant of hyperoxia by manipulation of mitochondrial electron transport. These observations may suggest new pharmaceutical strategies to diminish oxygen-mediated cellular damage.

  10. Chemical chaperones reduce ionizing radiation-induced endoplasmic reticulum stress and cell death in IEC-6 cells

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun Sang; Lee, Hae-June; Lee, Yoon-Jin [Division of Radiation Effects, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Jeong, Jae-Hoon [Division of Radiotherapy, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Kang, Seongman [Division of Life Sciences, Korea University, Seoul 136-701 (Korea, Republic of); Lim, Young-Bin, E-mail: yblim@kirams.re.kr [Division of Radiation Effects, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of)

    2014-07-25

    Highlights: • UPR activation precedes caspase activation in irradiated IEC-6 cells. • Chemical ER stress inducers radiosensitize IEC-6 cells. • siRNAs that targeted ER stress responses ameliorate IR-induced cell death. • Chemical chaperons prevent cell death in irradiated IEC-6 cells. - Abstract: Radiotherapy, which is one of the most effective approaches to the treatment of various cancers, plays an important role in malignant cell eradication in the pelvic area and abdomen. However, it also generates some degree of intestinal injury. Apoptosis in the intestinal epithelium is the primary pathological factor that initiates radiation-induced intestinal injury, but the mechanism by which ionizing radiation (IR) induces apoptosis in the intestinal epithelium is not clearly understood. Recently, IR has been shown to induce endoplasmic reticulum (ER) stress, thereby activating the unfolded protein response (UPR) signaling pathway in intestinal epithelial cells. However, the consequences of the IR-induced activation of the UPR signaling pathway on radiosensitivity in intestinal epithelial cells remain to be determined. In this study, we investigated the role of ER stress responses in IR-induced intestinal epithelial cell death. We show that chemical ER stress inducers, such as tunicamycin or thapsigargin, enhanced IR-induced caspase 3 activation and DNA fragmentation in intestinal epithelial cells. Knockdown of Xbp1 or Atf6 with small interfering RNA inhibited IR-induced caspase 3 activation. Treatment with chemical chaperones prevented ER stress and subsequent apoptosis in IR-exposed intestinal epithelial cells. Our results suggest a pro-apoptotic role of ER stress in IR-exposed intestinal epithelial cells. Furthermore, inhibiting ER stress may be an effective strategy to prevent IR-induced intestinal injury.

  11. Human cell line sensitive to mutation by particle-borne chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Crespi, C.L.; Liber, H.L.; Behymer, T.D.; Hites, R.A.; Thilly, W.G.

    1985-07-01

    A human lymphoblastoid cell line with ability to perform oxidative metabolism of various chemicals is mutated by the direct addition of an intact particulate soot. This experiment demonstrates that materials associated with combustion-generated particulates are biologically available and able to cause genetic changes in metabolically competent human cells.

  12. Reviews on Fuel Cell Technology for Valuable Chemicals and Energy Co-Generation

    Directory of Open Access Journals (Sweden)

    Wisitsree Wiyaratn

    2010-07-01

    Full Text Available This paper provides a review of co-generation process in fuel cell type reactor to produce valuable chemical compounds along with electricity. The chemicals and energy co-generation processes have been shown to be a promising alternative to conventional reactors and conventional fuel cells with pure water as a byproduct. This paper reviews researches on chemicals and energy co-generation technologies of three types of promising fuel cell i.e. solid oxide fuel cell (SOFC, alkaline fuel cell (AFC, and proton exchange membrane fuel cell (PEMFC. In addition, the research studies on applications of SOFCs, AFCs, and PEMFCs with chemical production (i.e. nitric oxide, formaldehyde, sulfur oxide, C2 hydrocarbons, alcohols, syngas and hydrogen peroxide were also given. Although, it appears that chemicals and energy co-generation processes have potential to succeed in commercial applications, the development of cheaper catalyst materials with longer stability ,and understanding in thermodynamic are still challenging to improve the overall system performance and enable to use in commercial market.

  13. Grasping the nature of the cell interior: from Physiological Chemistry to Chemical Biology.

    Science.gov (United States)

    Kyne, Ciara; Crowley, Peter B

    2016-08-01

    Current models of the cell interior emphasise its crowded, chemically complex and dynamically organised structure. Although the chemical composition of cells is known, the cooperative intermolecular interactions that govern cell ultrastructure are poorly understood. A major goal of biochemistry is to capture these myriad interactions in vivo. We consider the landmark discoveries that have shaped this objective, starting from the vitalist framework established by early natural philosophers. Through this historical revisionism, we extract important lessons for the bioinspired chemists of today. Scientific specialisation tends to insulate seminal ideas and hamper the unification of paradigms across biology. Therefore, we call for interdisciplinary collaboration in grappling with the complex cell interior. Recent successes in integrative structural biology and chemical biology demonstrate the power of hybrid approaches. The future roles of the (bio)chemist and model systems are also discussed as starting points for in vivo explorations. © 2016 Federation of European Biochemical Societies.

  14. Probing the bacterial cell wall with chemical biology tools

    NARCIS (Netherlands)

    Sminia, Tjerk J.

    2017-01-01

    After DNA and proteins, carbohydrates are the third language of life. Chapter 1 introduces the reader to this class of biomolecules, also called sugars or glycans, that can be found on the outer surface of almost all cells and plays a critical role as the social messengers of a

  15. Effects of Pristane on Cytochrome P450 Isozyme Expression in Rat Tissues

    Directory of Open Access Journals (Sweden)

    Marvin A. Cuchens

    2005-04-01

    Full Text Available Chemical carcinogenesis studies are powerful tools to obtain information on potential mechanisms of chemical factors for malignancies. In this study Western blot analyses, using monoclonal antibodies specific for three different cytochrome P450 (CYP isozymes (CYP1A1, CYP1A2 and CYP2B, were employed to examine the effect(s of 3-methylcholanthrene and/or pristane (2,6,10,14-tetramethylpentadecane on the basal and inducible levels of expression of CYP proteins within Copenhagen rat tissues. Pristane exposure led to tissue specific differences in the CYP isozymes expressed and elicited increased CYP protein expression over 3-methylcholanthrene induced levels in microsomes isolated from liver, Peyer's Patches, and thymus. Within the context of the chemical carcinogenesis model employed in this study, these observations correlated with the induction of B-cell malignancies by low doses of 3-methylcholanthrene and of thymic lymphomas by a high 3-methylcholanthrene dose. The data suggest that pristane treatment affects CYP isozyme expression. This pristane-mediated effect clearly could be a contributing factor in the chemical carcinogenesis of the previously observed lymphoid malignancies, and a possible basis for the tumor enhancing effects of pristane.

  16. Metformin inhibits 7,12-dimethylbenz[a]anthracene-induced breast carcinogenesis and adduct formation in human breast cells by inhibiting the cytochrome P4501A1/aryl hydrocarbon receptor signaling pathway

    Energy Technology Data Exchange (ETDEWEB)

    Maayah, Zaid H. [Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451 (Saudi Arabia); Ghebeh, Hazem [Stem Cell & Tissue Re-Engineering, King Faisal Specialist Hospital and Research Center, Riyadh 11211 (Saudi Arabia); Alhaider, Abdulqader A. [Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451 (Saudi Arabia); Camel Biomedical Research Unit, College of Pharmacy and Medicine, King Saud University, Riyadh 11451 (Saudi Arabia); El-Kadi, Ayman O.S. [Faculty of Pharmacy & Pharmaceutical Sciences, University of Alberta, Edmonton (Canada); Soshilov, Anatoly A.; Denison, Michael S. [Department of Environmental Toxicology, University of California at Davis, Davis, CA 95616 (United States); Ansari, Mushtaq Ahmad [Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451 (Saudi Arabia); Korashy, Hesham M., E-mail: hkorashy@ksu.edu.sa [Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh 11451 (Saudi Arabia)

    2015-04-15

    Recent studies have established that metformin (MET), an oral anti-diabetic drug, possesses antioxidant activity and is effective against different types of cancer in several carcinogen-induced animal models and cell lines. However, whether MET can protect against breast cancer has not been reported before. Therefore, the overall objectives of the present study are to elucidate the potential chemopreventive effect of MET in non-cancerous human breast MCF10A cells and explore the underlying mechanism involved, specifically the role of cytochrome P4501A1 (CYP1A1)/aryl hydrocarbon receptor (AhR) pathway. Transformation of the MCF10A cells into initiated breast cancer cells with DNA adduct formation was conducted using 7,12-dimethylbenz[a]anthracene (DMBA), an AhR ligand. The chemopreventive effect of MET against DMBA-induced breast carcinogenesis was evidenced by the capability of MET to restore the induction of the mRNA levels of basic excision repair genes, 8-oxoguanine DNA glycosylase (OGG1) and apurinic/apyrimidinic endonuclease1 (APE1), and the level of 8-hydroxy-2-deoxyguanosine (8-OHdG). Interestingly, the inhibition of DMBA-induced DNA adduct formation was associated with proportional decrease in CYP1A1 and in NAD(P)H:quinone oxidoreductase 1 (NQO1) gene expression. Mechanistically, the involvements of AhR and nuclear factor erythroid 2-related factor-2 (Nrf2) in the MET-mediated inhibition of DMBA-induced CYP1A1 and NQO1 gene expression were evidenced by the ability of MET to inhibit DMBA-induced xenobiotic responsive element and antioxidant responsive element luciferase reporter gene expression which suggests an AhR- and Nrf2-dependent transcriptional control. However, the inability of MET to bind to AhR suggests that MET is not an AhR ligand. In conclusion, the present work shows a strong evidence that MET inhibits the DMBA-mediated carcinogenicity and adduct formation by inhibiting the expression of CYP1A1 through an AhR ligand-independent mechanism

  17. Hydrogen fuel cells in chemical industry: The assemini project

    Energy Technology Data Exchange (ETDEWEB)

    Caserza, G.; Bozzoni, T.; Porcino, G.; Pasquinucci, A. [Ansaldo CLC s.r.l., Genova (Italy)] [and others

    1996-12-31

    Chemical and petrochemical industries generate large quantities of hydrogen-rich streams, in the range 50%-100% H{sub 2} concentration by volume, as by-products of electrochemical or dehydrogenation processes, or exhausts/purging in hydrogenation processes. Due to safety aspects, and because of the low density, which makes difficult transportation and storage, such streams often constitute a problem for plant managers. In most cases recycling within the plant processes is not possible, and transportation to other sites, generally by truck after compression in cylinders, is not economical. Many of these streams arc therefore simply co-burned in plant boilers, and in some cases even wasted by venting or flaring. Their value ranges from zero (if vented), to the value of the fuel used in the boiler, where they are co-burned.

  18. Chemically synthesized silver nanoparticles as cell lysis agent for bacterial genomic DNA isolation

    Science.gov (United States)

    Goswami, Gunajit; Boruah, Himangshu; Gautom, Trishnamoni; Jyoti Hazarika, Dibya; Barooah, Madhumita; Boro, Robin Chandra

    2017-12-01

    Silver nanoparticles (AgNPs) have seen a recent spurt of use in varied fields of science. In this paper, we showed a novel application of AgNP as a promising microbial cell-lysis agent for genomic DNA isolation. We utilized chemically synthesized AgNPs for lysing bacterial cells to isolate their genomic DNA. The AgNPs efficiently lysed bacterial cells to yield good quality DNA that could be subsequently used for several molecular biology works.

  19. A rapid chemical method for lysing Arabidopsis cells for protein analysis

    OpenAIRE

    Takano Tetsuo; Liu Shenkui; Tsugama Daisuke

    2011-01-01

    Abstract Background Protein extraction is a frequent procedure in biological research. For preparation of plant cell extracts, plant materials usually have to be ground and homogenized to physically break the robust cell wall, but this step is laborious and time-consuming when a large number of samples are handled at once. Results We developed a chemical method for lysing Arabidopsis cells without grinding. In this method, plants are boiled for just 10 minutes in a solution containing a Ca2+ ...

  20. Microsecond reaction kinetics and catalytic mechanism of bacterial cytochrome oxidases

    OpenAIRE

    Paulus, A

    2017-01-01

    Fundamental biochemical research is of crucial importance for a complete and detailedunderstanding of what drives enzyme activity and how enzyme kinetic properties areoptimized towards survival of the host organism. When cells fail to produce a fully functionalenzyme, the organism’s ability to survive or thrive is impacted. In humans, for example, lowlevels or absence of lactase causes lactose intolerance, while decreased performance of theproton-pumping enzyme cytochrome aa3 oxidase in the m...

  1. Fractionation of cytochromes of phototrophically grown Chloroflexus aurantiacus. Is there a cytochrome bc complex among them?

    Science.gov (United States)

    Yanyushin, Mikhail F

    2002-02-13

    The cytochrome-containing membrane complexes of the phototrophically grown green non-sulfur bacterium Chloroflexus aurantiacus were fractionated by anion exchange chromatography. Three cytochrome b and four cytochrome c peaks were observed. None of the separated complexes met the features of the cytochrome bc complex. Two main cytochrome b-containing complexes were further purified: a dimer of identical subunits with unknown function and a succinate:quinone oxidoreductase containing three subunit species. Two novel multisubunit complexes, similar to each other, with two heme c-bearing subunits were also purified.

  2. Beta-Amyloid Oligomers Activate Apoptotic BAK Pore for Cytochrome c Release

    Science.gov (United States)

    Kim, Jaewook; Yang, Yoosoo; Song, Seung Soo; Na, Jung-Hyun; Oh, Kyoung Joon; Jeong, Cherlhyun; Yu, Yeon Gyu; Shin, Yeon-Kyun

    2014-01-01

    In Alzheimer’s disease, cytochrome c-dependent apoptosis is a crucial pathway in neuronal cell death. Although beta-amyloid (Aβ) oligomers are known to be the neurotoxins responsible for neuronal cell death, the underlying mechanisms remain largely elusive. Here, we report that the oligomeric form of synthetic Aβ of 42 amino acids elicits death of HT-22 cells. But, when expression of a bcl-2 family protein BAK is suppressed by siRNA, Aβ oligomer-induced cell death was reduced. Furthermore, significant reduction of cytochrome c release was observed with mitochondria isolated from BAK siRNA-treated HT-22 cells. Our in vitro experiments demonstrate that Aβ oligomers bind to BAK on the membrane and induce apoptotic BAK pores and cytochrome c release. Thus, the results suggest that Aβ oligomers function as apoptotic ligands and hijack the intrinsic apoptotic pathway to cause unintended neuronal cell death. PMID:25296312

  3. Cytochrome bd Displays Significant Quinol Peroxidase Activity

    NARCIS (Netherlands)

    Al-attar, S.; Yu, Y.; Pinkse, M.W.H.; Hoeser, Jo; Friedrich, Thorsten; Bald, Dirk; de Vries, S.

    2016-01-01

    Cytochrome bd is a prokaryotic terminal oxidase that catalyses the electrogenic reduction of oxygen to water using ubiquinol as electron donor. Cytochrome bd is a tri-haem integral membrane enzyme carrying a low-spin haem b558, and two high-spin haems: b595 and d. Here we

  4. Cytochrome P450 enzyme systems in fungi

    NARCIS (Netherlands)

    Brink, H.M. van den; Gorcom, R.F.M. van; Hondel, C.A.M.J.J. van den; Punt, P.J.

    1998-01-01

    The involvement of cytochrome P450 enzymes in many complex fungal bioconversion processes has been characterized in recent years. Accordingly, there is now considerable scientific interest in fungal cytochrome P450 enzyme systems. In contrast to S. cerevisiae, where surprisingly few P450 genes have

  5. Chemical Screening Using Cell-FreeXenopusEgg Extract.

    Science.gov (United States)

    Broadus, Matthew R; Lee, Ethan

    2018-02-23

    Most drug screening methods use purified proteins, cultured cells, and/or small model organisms such as Xenopus , zebrafish, flies, or nematodes. These systems have proven successes in drug discovery, but they also have weaknesses. Although purified cellular components allow for identification of compounds with activity against specific targets, such systems lack the complex biological interactions present in cellular and organismal screens. In vivo systems overcome these weaknesses, but the lack of cellular permeability, efflux by cellular pumps, and/or toxicity can be major limitations. Xenopus laevis egg extract, a concentrated and biologically active cytosol, can potentially overcome these weaknesses. Drug interactions occur in a near-physiological milieu, thereby functioning in a "truer" endogenous manner than purified components. Also, Xenopus egg extract is a cell-free system that lacks intact plasma membranes that could restrict drug access to potential targets. Finally, Xenopus egg extract is readily manipulated at the protein level: Proteins are easily depleted or added to the system, an important feature for analyzing drug effects in disease states. Thus, Xenopus egg extract offers an attractive media for screening drugs that merges strengths of both in vitro and in vivo systems. © 2018 Cold Spring Harbor Laboratory Press.

  6. Understanding chemically processed solar cells based on quantum dots.

    Science.gov (United States)

    Malgras, Victor; Nattestad, Andrew; Kim, Jung Ho; Dou, Shi Xue; Yamauchi, Yusuke

    2017-01-01

    Photovoltaic energy conversion is one of the best alternatives to fossil fuel combustion. Petroleum resources are now close to depletion and their combustion is known to be responsible for the release of a considerable amount of greenhouse gases and carcinogenic airborne particles. Novel third-generation solar cells include a vast range of device designs and materials aiming to overcome the factors limiting the current technologies. Among them, quantum dot-based devices showed promising potential both as sensitizers and as colloidal nanoparticle films. A good example is the p-type PbS colloidal quantum dots (CQDs) forming a heterojunction with a n-type wide-band-gap semiconductor such as TiO2 or ZnO. The confinement in these nanostructures is also expected to result in marginal mechanisms, such as the collection of hot carriers and generation of multiple excitons, which would increase the theoretical conversion efficiency limit. Ultimately, this technology could also lead to the assembly of a tandem-type cell with CQD films absorbing in different regions of the solar spectrum.

  7. Understanding chemically processed solar cells based on quantum dots

    Science.gov (United States)

    Malgras, Victor; Nattestad, Andrew; Kim, Jung Ho; Dou, Shi Xue; Yamauchi, Yusuke

    2017-01-01

    Abstract Photovoltaic energy conversion is one of the best alternatives to fossil fuel combustion. Petroleum resources are now close to depletion and their combustion is known to be responsible for the release of a considerable amount of greenhouse gases and carcinogenic airborne particles. Novel third-generation solar cells include a vast range of device designs and materials aiming to overcome the factors limiting the current technologies. Among them, quantum dot-based devices showed promising potential both as sensitizers and as colloidal nanoparticle films. A good example is the p-type PbS colloidal quantum dots (CQDs) forming a heterojunction with a n-type wide-band-gap semiconductor such as TiO2 or ZnO. The confinement in these nanostructures is also expected to result in marginal mechanisms, such as the collection of hot carriers and generation of multiple excitons, which would increase the theoretical conversion efficiency limit. Ultimately, this technology could also lead to the assembly of a tandem-type cell with CQD films absorbing in different regions of the solar spectrum. PMID:28567179

  8. Chemically tunable mucin chimeras assembled on living cells

    Science.gov (United States)

    Kramer, Jessica R.; Onoa, Bibiana; Bustamante, Carlos; Bertozzi, Carolyn R.

    2015-01-01

    Mucins are a family of secreted and transmembrane glycoproteins characterized by a massive domain of dense O-glycosylation on serine and threonine residues. Mucins are intimately involved in immunity and cancer, yet elucidation of the biological roles of their glycodomains has been complicated by their massive size, domain polymorphisms, and variable glycosylation patterns. Here we developed a synthetic route to a library of compositionally defined, high-molecular weight, dual end-functionalized mucin glycodomain constructs via N-carboxyanhydride polymerization. These glycopolypeptides are the first synthetic analogs to our knowledge to feature the native α-GalNAc linkage to serine with molecular weights similar to native mucins, solving a nearly 50-year synthetic challenge. Physical characterization of the mimics revealed insights into the structure and properties of mucins. The synthetic glycodomains were end-functionalized with an optical probe and a tetrazine moiety, which allowed site-specific bioorthogonal conjugation to an engineered membrane protein on live mammalian cells. This strategy in protein engineering will open avenues to explore the biological roles of cell surface mucins. PMID:26420872

  9. Integrating artificial with natural cells to translate chemical messages that direct E. coli behaviour

    Science.gov (United States)

    Lentini, Roberta; Santero, Silvia Perez; Chizzolini, Fabio; Cecchi, Dario; Fontana, Jason; Marchioretto, Marta; Del Bianco, Cristina; Terrell, Jessica L.; Spencer, Amy C.; Martini, Laura; Forlin, Michele; Assfalg, Michael; Serra, Mauro Dalla; Bentley, William E.; Mansy, Sheref S.

    2014-01-01

    Previous efforts to control cellular behaviour have largely relied upon various forms of genetic engineering. Once the genetic content of a living cell is modified, the behaviour of that cell typically changes as well. However, other methods of cellular control are possible. All cells sense and respond to their environment. Therefore, artificial, non-living cellular mimics could be engineered to activate or repress already existing natural sensory pathways of living cells through chemical communication. Here we describe the construction of such a system. The artificial cells expand the senses of Escherichia coli by translating a chemical message that E. coli cannot sense on its own to a molecule that activates a natural cellular response. This methodology could open new opportunities in engineering cellular behaviour without exploiting genetically modified organisms. PMID:24874202

  10. Integrating artificial with natural cells to translate chemical messages that direct E. coli behaviour.

    Science.gov (United States)

    Lentini, Roberta; Santero, Silvia Perez; Chizzolini, Fabio; Cecchi, Dario; Fontana, Jason; Marchioretto, Marta; Del Bianco, Cristina; Terrell, Jessica L; Spencer, Amy C; Martini, Laura; Forlin, Michele; Assfalg, Michael; Dalla Serra, Mauro; Bentley, William E; Mansy, Sheref S

    2014-05-30

    Previous efforts to control cellular behaviour have largely relied upon various forms of genetic engineering. Once the genetic content of a living cell is modified, the behaviour of that cell typically changes as well. However, other methods of cellular control are possible. All cells sense and respond to their environment. Therefore, artificial, non-living cellular mimics could be engineered to activate or repress already existing natural sensory pathways of living cells through chemical communication. Here we describe the construction of such a system. The artificial cells expand the senses of Escherichia coli by translating a chemical message that E. coli cannot sense on its own to a molecule that activates a natural cellular response. This methodology could open new opportunities in engineering cellular behaviour without exploiting genetically modified organisms.

  11. Experimental validation of crystalline silicon solar cells recycling by thermal and chemical methods

    Energy Technology Data Exchange (ETDEWEB)

    Klugmann-Radziemska, Ewa; Ostrowski, Piotr [Gdansk University of Technology, Chemical Faculty, Narutowicza 11/12, PL 80-233 Gdansk (Poland); Drabczyk, Kazimierz; Panek, Piotr [Polish Academy of Sciences, Institute of Metallurgy and Materials Science (Poland); Szkodo, Marek [Gdansk University of Technology, Faculty of Mechanical Engineering (Poland)

    2010-12-15

    In recent years, photovoltaic power generation systems have been gaining unprecedented attention as an environmentally beneficial method for solving the energy problem. From the economic point of view pure silicon, which can be recovered from spent cells, is the most important material owing to its cost and limited supply. The article presents a chemical method for recycling spent or damaged modules and cells, and the results of its experimental validation. The recycling of PV cells consists of two main steps: the separation of cells and their refinement. Cells are first separated thermally or chemically; the separated cells are then refined. During this process the antireflection, metal coating and p-n junction layers are removed in order to recover the silicon base, ready for its next use. This refinement step was performed using an optimised chemical method. Silicon wafers were examined with an environmental scanning electron microscope (ESEM) coupled to an EDX spectrometer. The silicon wafers were used for producing new silicon solar cells, which were then examined and characterized with internal spectral response and current-voltage characteristics. The new cells, despite the fact that they have no SiN{sub x} antireflective coating, have a very good efficiency of 13-15%. (author)

  12. Tailoring the Interfacial Chemical Interaction for High-Efficiency Perovskite Solar Cells.

    Science.gov (United States)

    Zuo, Lijian; Chen, Qi; De Marco, Nicholas; Hsieh, Yao-Tsung; Chen, Huajun; Sun, Pengyu; Chang, Sheng-Yung; Zhao, Hongxiang; Dong, Shiqi; Yang, Yang

    2017-01-11

    The ionic nature of perovskite photovoltaic materials makes it easy to form various chemical interactions with different functional groups. Here, we demonstrate that interfacial chemical interactions are a critical factor in determining the optoelectronic properties of perovskite solar cells. By depositing different self-assembled monolayers (SAMs), we introduce different functional groups onto the SnO2 surface to form various chemical interactions with the perovskite layer. It is observed that the perovskite solar cell device performance shows an opposite trend to that of the energy level alignment theory, which shows that chemical interactions are the predominant factor governing the interfacial optoelectronic properties. Further analysis verifies that proper interfacial interactions can significantly reduce trap state density and facilitate the interfacial charge transfer. Through use of the 4-pyridinecarboxylic acid SAM, the resulting perovskite solar cell exhibits striking improvements to the reach the highest efficiency of 18.8%, which constitutes an ∼10% enhancement compared to those without SAMs. Our work highlights the importance of chemical interactions at perovskite/electrode interfaces and paves the way for further optimizing performances of perovskite solar cells.

  13. In vivo stem cell tracking with imageable nanoparticles that bind bioorthogonal chemical receptors on the stem cell surface.

    Science.gov (United States)

    Lee, Sangmin; Yoon, Hwa In; Na, Jin Hee; Jeon, Sangmin; Lim, Seungho; Koo, Heebeom; Han, Sang-Soo; Kang, Sun-Woong; Park, Soon-Jung; Moon, Sung-Hwan; Park, Jae Hyung; Cho, Yong Woo; Kim, Byung-Soo; Kim, Sang Kyoon; Lee, Taekwan; Kim, Dongkyu; Lee, Seulki; Pomper, Martin G; Kwon, Ick Chan; Kim, Kwangmeyung

    2017-09-01

    It is urgently necessary to develop reliable non-invasive stem cell imaging technology for tracking the in vivo fate of transplanted stem cells in living subjects. Herein, we developed a simple and well controlled stem cell imaging method through a combination of metabolic glycoengineering and bioorthogonal copper-free click chemistry. Firstly, the exogenous chemical receptors containing azide (-N3) groups were generated on the surfaces of stem cells through metabolic glycoengineering using metabolic precursor, tetra-acetylated N-azidoacetyl-d-mannosamine(Ac4ManNAz). Next, bicyclo[6.1.0]nonyne-modified glycol chitosan nanoparticles (BCN-CNPs) were prepared as imageable nanoparticles to deliver different imaging agents. Cy5.5, iron oxide nanoparticles and gold nanoparticles were conjugated or encapsulated to BCN-CNPs for optical, MR and CT imaging, respectively. These imageable nanoparticles bound chemical receptors on the Ac4ManNAz-treated stem cell surface specifically via bioorthogonal copper-free click chemistry. Then they were rapidly taken up by the cell membrane turn-over mechanism resulting in higher endocytic capacity compared non-specific uptake of nanoparticles. During in vivo animal test, BCN-CNP-Cy5.5-labeled stem cells could be continuously tracked by non-invasive optical imaging over 15 days. Furthermore, BCN-CNP-IRON- and BCN-CNP-GOLD-labeled stem cells could be efficiently visualized using in vivo MR and CT imaging demonstrating utility of our stem cell labeling method using chemical receptors. These results conclude that our method based on metabolic glycoengineering and bioorthogonal copper-free click chemistry can stably label stem cells with diverse imageable nanoparticles representing great potential as new stem cell imaging technology. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Characterization of human cytochrome P450 induction by pesticides.

    Science.gov (United States)

    Abass, Khaled; Lämsä, Virpi; Reponen, Petri; Küblbeck, Jenni; Honkakoski, Paavo; Mattila, Sampo; Pelkonen, Olavi; Hakkola, Jukka

    2012-03-29

    Pesticides are a large group of structurally diverse toxic chemicals. The toxicity may be modified by cytochrome P450 (CYP) enzyme activity. In the current study, we have investigated effects and mechanisms of 24 structurally varying pesticides on human CYP expression. Many pesticides were found to efficiently activate human pregnane X receptor (PXR) and/or constitutive androstane receptor (CAR). Out of the 24 compounds tested, 14 increased PXR- and 15 CAR-mediated luciferase activities at least 2-fold. While PXR was predominantly activated by pyrethroids, CAR was, in addition to pyrethroids, well activated by organophosphates and several carbamates. Induction of CYP mRNAs and catalytic activities was studied in the metabolically competent, human derived HepaRG cell line. CYP3A4 mRNA was induced most powerfully by pyrethroids; 50 μM cypermethrin increased CYP3A4 mRNA 35-fold. CYP2B6 was induced fairly equally by organophosphate, carbamate and pyrethroid compounds. Induction of CYP3A4 and CYP2B6 by these compound classes paralleled their effects on PXR and CAR. The urea herbicide diuron and the triazine herbicide atrazine induced CYP2B6 mRNA more than 10-fold, but did not activate CAR indicating that some pesticides may induce CYP2B6 via CAR-independent mechanisms. CYP catalyzed activities were induced much less than the corresponding mRNAs. At least in some cases, this is probably due to significant inhibition of CYP enzymes by the studied pesticides. Compared with human CAR activation and CYP2B6 expression, pesticides had much less effect on mouse CAR and CYP2B10 mRNA. Altogether, pesticides were found to be powerful human CYP inducers acting through both PXR and CAR. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  15. Use of Chemical Oxygen Demand Values of Bacterial Cells in Waste-Water Purification

    Science.gov (United States)

    Gaudy, A. F.; Bhatla, M. N.; Gaudy, E. T.

    1964-01-01

    Four methods for determining substrate recoveries in studies concerned with the partition of substrate between sludge synthesis and respiration were investigated. An energy balance comparing chemical oxygen demand (COD) removed with the summation of oxygen uptake and the COD of the cells produced yielded average recoveries closer to 100% than any of the other three methods tested. The standard COD test was shown to yield highly reproducible values when used to determine the COD of activated sludge. Although the protein and carbohydrate content of the cells varied with cell age, a concomitant variation in cell COD was not noted. PMID:14170964

  16. Wet-chemical approach for the cell-adhesive modification of polytetrafluoroethylene

    Energy Technology Data Exchange (ETDEWEB)

    Gabriel, Matthias; Dahm, Manfred; Vahl, Christian-F, E-mail: mgabriel@uni-mainz.de [Department of Cardiothoracic and Vascular Surgery, Johannes Gutenberg-University School of Medicine, Mainz (Germany)

    2011-06-15

    Polytetrafluoroethylene (PTFE), a frequently utilized polymer for the fabrication of synthetic vascular grafts, was surface-modified by means of a wet-chemical process. The inherently non-cell-adhesive polymer does not support cellular attachment, a prerequisite for the endothelialization of luminal surface grafts in small diameter applications. To impart the material with cell-adhesive properties a treatment with sodium-naphthalene provided a basis for the subsequent immobilization of the adhesion promoting RGD-peptide using a hydroxy- and amine-reactive crosslinker. Successful conjugation was shown with cell culture experiments which demonstrated excellent endothelial cell growth on the modified surfaces.

  17. Amniotic membrane traps and induces apoptosis of inflammatory cells in ocular surface chemical burn

    Science.gov (United States)

    Liu, Ting; Zhai, Hualei; Xu, Yuanyuan; Dong, Yanling; Sun, Yajie; Zang, Xinjie

    2012-01-01

    Purpose Severe chemical burns can cause necrosis of ocular surface tissues following the infiltration of inflammatory cells. It has been shown that amniotic membrane transplantation (AMT) is an effective treatment for severe chemical burns, but the phenotypes of cells that infiltrate the amniotic membrane and the clinical significance of these cellular infiltrations have not previously been reported. The present work studies the inflammation cell traps and apoptosis inducing roles of the amniotic membrane after AMT in patients with acute chemical burns. Methods A total of 30 patients with acute alkaline burns were classified as having either moderate or severe burns. In all participants, AMT was performed within one week of his/her injury. After 7–9 days, the transplanted amniotic membranes were removed. Histopathological and immunohistochemical techniques were used for the examination and detection of infiltrating cells, and tests for the expression of CD (cluster of differentiation)15, CD68, CD3, CD20, CD57, CD31, CD147, and CD95 (Fas) were performed. A TUNEL (TdT-mediated dUTP nick end labeling) assay was used to confirm apoptosis of the infiltrating cells. Three patients with herpes simplex-induced keratitis who had undergone AMT to treat persistent epithelium defects were used as a control group. Amniotic membrane before transplantation was used as another control. Results After amniotic membrane transplantation, the number of infiltrating cells in patients with severe burns was significantly higher than in patients with moderate burns or in control patients (pburns patients, CD15 and CD68 were widely expressed in the infiltrating cells, and CD3, CD20, and CD57 were only found in a small number of cells. Occasionally, CD31-positive cells were found in the amniotic membranes. More cells that were CD147, Fas, and TUNEL positive were found in patients with severe burns than in patients with moderate burns or in control patients. Conclusions Neutrophils and

  18. Inhibition of NADPH cytochrome P450 reductase by the model sulfur mustard vesicant 2-chloroethyl ethyl sulfide is associated with increased production of reactive oxygen species.

    Science.gov (United States)

    Gray, Joshua P; Mishin, Vladimir; Heck, Diane E; Laskin, Debra L; Laskin, Jeffrey D

    2010-09-01

    Inhalation of vesicants including sulfur mustard can cause significant damage to the upper airways. This is the result of vesicant-induced modifications of proteins important in maintaining the integrity of the lung. Cytochrome P450s are the major enzymes in the lung mediating detoxification of sulfur mustard and its metabolites. NADPH cytochrome P450 reductase is a flavin-containing electron donor for cytochrome P450. The present studies demonstrate that the sulfur mustard analog, 2-chloroethyl ethyl sulfide (CEES), is a potent inhibitor of human recombinant cytochrome P450 reductase, as well as native cytochrome P450 reductase from liver microsomes of saline and beta-naphthoflavone-treated rats, and cytochrome P450 reductase from type II lung epithelial cells. Using rat liver microsomes from beta-naphthoflavone-treated rats, CEES was found to inhibit CYP 1A1 activity. This inhibition was overcome by microsomal cytochrome P450 reductase from saline-treated rats, which lack CYP 1A1 activity, demonstrating that the CEES inhibitory activity was selective for cytochrome P450 reductase. Cytochrome P450 reductase also generates reactive oxygen species (ROS) via oxidation of NADPH. In contrast to its inhibitory effects on the reduction of cytochrome c and CYP1A1 activity, CEES was found to stimulate ROS formation. Taken together, these data demonstrate that sulfur mustard vesicants target cytochrome P450 reductase and that this effect may be an important mechanism mediating oxidative stress and lung injury. 2010. Published by Elsevier Inc.

  19. Monochromosomal hybrid cell assay for evaluating the genotoxicity of environmental chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Sandhu, S.S.; Gudi, R.D.; Athwal, R.S.

    1988-12-01

    The development and utilization of a monochromosomal hybrid cell assay for detecting aneuploidy and chromosomal aberrations are described. The monochromosomal hybrid cell lines were produced by a two-step process involving transfer of a marker bacterial gene to a human chromosome and then by integration of that human chromosome into a mouse complement of chromosomes through microcell fusion. For chemically induced aneuploidy, the segregation of a single human chromosome among mouse chromosomes is used as a cytogenetic marker. The genetic assay for aneuploidy is based on the ability of the cells to grow in a medium that selects for the loss of the human chromosome. The assay for clastogenicity is based on survival of the cells after treatment with the chemicals in medium that selects for retention of the human chromosome but loss of its segment containing diphtheria toxin locus. The assays greatly simplify the detection of chromosomal aberrations induced by environmental factors at low-dose levels.

  20. EPR Characterization of the Triheme Cytochrome from Geobacter sulfurreducens.

    Science.gov (United States)

    Ponomarenko, Nina; Niklas, Jens; Pokkuluri, Phani Raj; Poluektov, Oleg G; Tiede, David Michael

    2018-01-03

    Periplasmic cytochrome A (PpcA) is a representative of a broad class of multi-heme cytochromes functioning as protein "nanowires" for storage and extracellular transfer of multiple electrons in the δ-proteobacterium Geobacter sulfurreducens. PpcA contains three bis-His coordinated hemes held in a spatial arrangement that is highly conserved among the multi-heme cytochromes c3 and c7 families, carries low potential hemes and is notable for having one of the lowest number of amino acids utilized to maintain a characteristic protein fold and site specific heme function. Low temperature X-band EPR spectroscopy has been used to characterize the electronic configuration of the Fe(III) and the ligation mode for each heme. The three sets of EPR signals are assigned to individual hemes in the 3D crystal structure. The relative energy levels of the Fe(III) 3d orbitals for individual hemes was estimated from the principal g values. The observed g tensor anisotropy was used as a probe of electronic structure of each heme and differences were determined by specifics of axial ligation. To ensure unambiguous assignment of highly anisotropic low spin (HALS) signal to individual hemes, EPR analyses of iron atom electronic configurations have been supplemented with investigation of porphyrin macrocycles by 1D 1H NMR chemical shift patterns for the methyl substituents. Within optimized geometry of hemes in PpcA the magnetic interactions between hemes were found to be minimal, similar to c3 family of tetraheme cytochromes.

  1. Importance of c-Type cytochromes for U(VI reduction by Geobacter sulfurreducens

    Directory of Open Access Journals (Sweden)

    Leang Ching

    2007-03-01

    Full Text Available Abstract Background In order to study the mechanism of U(VI reduction, the effect of deleting c-type cytochrome genes on the capacity of Geobacter sulfurreducens to reduce U(VI with acetate serving as the electron donor was investigated. Results The ability of several c-type cytochrome deficient mutants to reduce U(VI was lower than that of the wild type strain. Elimination of two confirmed outer membrane cytochromes and two putative outer membrane cytochromes significantly decreased (ca. 50–60% the ability of G. sulfurreducens to reduce U(VI. Involvement in U(VI reduction did not appear to be a general property of outer membrane cytochromes, as elimination of two other confirmed outer membrane cytochromes, OmcB and OmcC, had very little impact on U(VI reduction. Among the periplasmic cytochromes, only MacA, proposed to transfer electrons from the inner membrane to the periplasm, appeared to play a significant role in U(VI reduction. A subpopulation of both wild type and U(VI reduction-impaired cells, 24–30%, accumulated amorphous uranium in the periplasm. Comparison of uranium-accumulating cells demonstrated a similar amount of periplasmic uranium accumulation in U(VI reduction-impaired and wild type G. sulfurreducens. Assessment of the ability of the various suspensions to reduce Fe(III revealed no correlation between the impact of cytochrome deletion on U(VI reduction and reduction of Fe(III hydroxide and chelated Fe(III. Conclusion This study indicates that c-type cytochromes are involved in U(VI reduction by Geobacter sulfurreducens. The data provide new evidence for extracellular uranium reduction by G. sulfurreducens but do not rule out the possibility of periplasmic uranium reduction. Occurrence of U(VI reduction at the cell surface is supported by the significant impact of elimination of outer membrane cytochromes on U(VI reduction and the lack of correlation between periplasmic uranium accumulation and the capacity for uranium

  2. Synchronization dynamics of chemically coupled cells with activator–inhibitor pathways

    Energy Technology Data Exchange (ETDEWEB)

    Guemkam Ghomsi, P. [Complex Systems and Theoretical Biology Group, Laboratory of Research on Advanced Materials and Nonlinear Science (LaRAMaNS), Department of Physics, Faculty of Science, University of Buea, P.O. Box 63, Buea (Cameroon); Laboratoire de Mécanique, Department of Physics, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé (Cameroon); Moukam Kakmeni, F.M., E-mail: moukam.kakmeni@ubuea.cm [Complex Systems and Theoretical Biology Group, Laboratory of Research on Advanced Materials and Nonlinear Science (LaRAMaNS), Department of Physics, Faculty of Science, University of Buea, P.O. Box 63, Buea (Cameroon); Kofane, T.C.; Tchawoua, C. [Laboratoire de Mécanique, Department of Physics, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé (Cameroon)

    2014-08-01

    Systems of interacting cells containing an activator–inhibitor pathway, regulating naturally in their inner parts their end-product concentrations through a sequence of biochemical reactions with feedback-loops: an end-product inhibition of the first substrate, and an autocatalytic activation of the end-product through an allosteric enzyme-mediated reaction are investigated. The individual cells are considered to be identical and are described by nonlinear differential equations recently proposed following the concerted transition model. The chemical and electrical coupling types, realized by exchange of metabolites across concentration of the cells are used in order to analyze the onset of phase and complete synchronization in the biochemical system. It is found that depending on the coupling nature and the range of coupling strength, cells enter into different synchronization regimes going from low-quality to high-quality synchronization. The synchronization manifold's stability is analyzed. The results are supported by numerical simulations using indicators such as the conditional Lyapunov exponents and the rate of change of the Lyapunov function. The results indicate that the system cannot completely synchronize under the single action of the chemical coupling. The combined effect of both chemical and electrical couplings is found to be of capital importance in the onset of complete synchronization and high quality synchronization. - Highlights: • We investigate the dynamics and synchronization of cells with activator–inhibitor pathways. • A complete study of fixed points' stability and bifurcations of the system is done. • It is found that chemically coupled cells only display phase synchronization. • Electrical coupling is important for complete synchronization in the coupled cells. • High quality synchronization is observed in the coupled cells.

  3. Chemical UV Filters Mimic the Effect of Progesterone on Ca(2+) Signaling in Human Sperm Cells

    DEFF Research Database (Denmark)

    Rehfeld, A; Dissing, S; Skakkebæk, N E

    2016-01-01

    Progesterone released by cumulus cells surrounding the egg induces a Ca(2+) influx into human sperm cells via the cationic channel of sperm (CatSper) Ca(2+) channel and controls multiple Ca(2+)-dependent responses essential for fertilization. We hypothesized that chemical UV filters may mimic...... competitively inhibited progesterone-induced Ca(2+) signals. In vivo exposure studies are needed to investigate whether UV filter exposure affects human fertility....

  4. Mixed Electrical-Chemical Transmission between Hippocampal Mossy Fibers and Pyramidal Cells

    Science.gov (United States)

    Vivar, Carmen; Traub, Roger D.; Gutiérrez, Rafael

    2011-01-01

    Morphological and electrophysiological studies have shown that granule cell axons, the mossy fibers (MFs), establish gap junctions and, therefore, electrical communication among them. That granule cells express gap junctional proteins in their axons suggests the possibility that their terminals express them as well. If this were to be the case, mixed electrical-chemical communication could be supported, as MF terminals normally use glutamate for fast communication with their target cells. Here we present electrophysiological and modeling studies consistent with this hypothesis. We show that MF activation produced fast spikelets followed by excitatory postsynaptic potentials in pyramidal cells (PCs), which, unlike the spikelets, underwent frequency potentiation and were strongly depressed by activation of metabotropic glutamate receptors, as expected from transmission of MF origin. The spikelets, which persisted during blockade of chemical transmission, wee potentiated by dopamine and suppressed by the gap junction blocker carbenoxolone. The various waveforms evoked by MF stimulation were replicated in a multi-compartment model of a PC by brief current pulse injections into the proximal apical dendritic compartment, where MFs are known to contact PCs. Mixed electrical and glutamatergic communication between granule cells and some PCs in CA3 may ensure the activation of sets of PCs, bypassing the strong action of concurrent feed-forward inhibition that granule cells activate. Importantly, MF-to-PC electrical coupling may allow bidirectional, possibly graded communication that can be faster than chemical synapses and subject to different forms of modulation. PMID:22151275

  5. Establishment of the first humpback whale fibroblast cell lines and their application in chemical risk assessment.

    Science.gov (United States)

    Burkard, Michael; Whitworth, Deanne; Schirmer, Kristin; Nash, Susan Bengtson

    2015-10-01

    This paper reports the first successful derivation and characterization of humpback whale fibroblast cell lines. Primary fibroblasts were isolated from the dermal connective tissue of skin biopsies, cultured at 37 °C and 5% CO2 in the standard mammalian medium DMEM/F12 supplemented with 10% fetal bovine serum (FBS). Of nine initial biopsies, two cell lines were established from two different animals and designated HuWa1 and HuWa2. The cells have a stable karyotype with 2n=44, which has commonly been observed in other baleen whale species. Cells were verified as being fibroblasts based on their spindle-shaped morphology, adherence to plastic and positive immunoreaction to vimentin. Population doubling time was determined to be ∼41 h and cells were successfully cryopreserved and thawed. To date, HuWa1 cells have been propagated 30 times. Cells proliferate at the tested temperatures, 30, 33.5 and 37 °C, but show the highest rate of proliferation at 37 °C. Short-term exposure to para,para'-dichlorodiphenyldichloroethylene (p,p'-DDE), a priority compound accumulating in southern hemisphere humpback whales, resulted in a concentration-dependent loss of cell viability. The effective concentration which caused a 50% reduction in HuWa1 cell viability (EC50 value) was approximately six times greater than the EC50 value for the same chemical measured with human dermal fibroblasts. HuWa1 exposed to a natural, p,p'-DDE-containing, chemical mixture extracted from whale blubber showed distinctively higher sensitivity than to p,p'-DDE alone. Thus, we provide the first cytotoxicological data for humpback whales and with establishment of the HuWa cell lines, a unique in vitro model for the study of the whales' sensitivity and cellular response to chemicals and other environmental stressors. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Intronic polymorphisms of cytochromes P450

    OpenAIRE

    Ingelman-Sundberg Magnus; Sim Sarah C

    2010-01-01

    Abstract The cytochrome P450 enzymes active in drug metabolism are highly polymorphic. Most allelic variants have been described for enzymes encoded by the cytochrome P450 family 2 (CYP2) gene family, which has 252 different alleles. The intronic polymorphisms in the cytochrome P450 genes account for only a small number of the important variant alleles; however, the most important ones are CYP2D6*4 and CYP2D6*41, which cause abolished and reduced CYP2D6 activity, respectively, and CYP3A5*3 an...

  7. Comparison of Chemical-induced Changes in Proliferation and Apoptosis in Human and Mouse Neuroprogenitor Cells.***

    Science.gov (United States)

    There is a need to develop rapid and efficient models to screen chemicals for their potential to cause developmental neurotoxicity. Use of in vitro neuronal models, including human cells, is one approach that allows for timely, cost-effective toxicity screening. The present study...

  8. COMPARISON OF CHEMICAL-INDUCED CHANGES IN PROLIFERATION AND APOPTOSIS IN HUMAN AND MOUSE NEUROPROGENITOR CELLS.

    Science.gov (United States)

    There is a need to develop rapid and efficient models for screening chemicals for their potential to cause developmental neurotoxicity. Use of in vitro neuronal models, including human cells, is one approach that allows for timely, cost-effective toxicity screening. The present s...

  9. Relating polymer chemical structure to the stability of polymer: : fullerene solar cells

    NARCIS (Netherlands)

    Doumon, Nutifafa Y.; Wang, Gongbao; Chiechi, Ryan; Koster, Lambert

    2017-01-01

    The design of novel polymers has brought more attention to bulk heterojunction polymer:fullerene solar cells in the past decade. A typical example is the synthesis, through chemical structure engineering, of the benzodithiophene-co-thieno[3,4-b]thiophene (BDT-TT) polymers leading to power conversion

  10. Chemically modified tetracyclines stimulate matrix metalloproteinase-s production by periodontal ligament cells

    NARCIS (Netherlands)

    Bildt, M.M.; Snoek-van Beurden, A.M.P.; Groot, J. de; El, B. van; Kuijpers-Jagtman, A.M.; Hoff, J.W. van den

    2006-01-01

    Background and Objective: The purpose of this study was to investigate the effects of chemically modified tetracyclines (CMTs) on the production of gelatinases [matrix metalloproteinase (MMP)-2 and -9] by human periodontal ligament (PDL) cells, and on the activity of recombinant gelatinases.

  11. Elucidation of the chemical fine structure of polysaccharides from soybean and maize kernel cell walls

    NARCIS (Netherlands)

    Huisman, M.M.H.

    2000-01-01

    The subject of this thesis was the elucidation of the chemical fine structure of polysaccharides from cell walls of soybean and maize kernel. The two species investigated represent different taxonomic groups, soybean belonging to the dicotyledonous and maize to the monocotyledonous plants.

  12. Cobalt toxicity: Chemical and radiological combined effects on HaCaT keratinocyte cell line

    Energy Technology Data Exchange (ETDEWEB)

    Gault, N. [CEA Fontenay aux Roses, DSV/IRCM/SCSR/LRTS, 92265 Fontenay aux Rose (France); Sandre, C.; Moulin, B.; Bresson, C. [CEA, DEN, SECR, Laboratoire de Speciation des Radionucleides et des Molecules, F-91191 Gif-sur-Yvette (France); Poncy, J.L. [CEA Bruyeres Le Chatel, DSV/IRCM/SREIT/LRT, 91680 Bruyeres Le Chatel (France); Lefaix, J.L. [CEA Caen, DSV/IRCM/SRO/LARIA, 14070 Caen (France)

    2010-07-01

    Cobalt (Co) is an essential trace element well known as a constituent of vitamin B12, but different compounds of Co are also described as highly toxic and/or radio-toxic for individuals or the environment. In nuclear power plants, {sup 58}Co and {sup 60}Co are radioactive isotopes of cobalt present as activation products of stable Co and Ni used in alloys. Skin exposure is a current occupational risk in the hard metal and nuclear industries. As biochemical and molecular cobalt-induced toxicological mechanisms are not fully identified, we investigated cobalt toxicity in a model human keratinocyte cell line, HaCaT. In this study, we propose a model to determine the in vitro chemical impact on cell viability of a soluble form of cobalt (CoCl{sub 2}) with or without {gamma}-ray doses to mimic contamination by {sup 60}Co, to elucidate the mechanisms of cobalt intracellular chemical and radiological toxicity. Intracellular cobalt concentration was determined after HaCaT cell contamination and chemical toxicity was evaluated in terms of cellular viability and clonogenic survival. We investigated damage to DNA in HaCaT cells by combined treatment with chemical cobalt and a moderate {gamma}-ray dose. Additive effects of cobalt and irradiation were demonstrated. The underlying mechanism of cobalt toxicity is not clearly established, but our results seem to indicate that the toxicity of Co(II) and of irradiation arises from production of reactive oxygen species. (authors)

  13. Effects of solvents and dosing procedure on chemical toxicity in cell-based in vitro assays.

    NARCIS (Netherlands)

    Tanneberger, K.; Rico Rico, A.; Kramer, N.I.; Busser, F.J.M.; Hermens, J.L.M.; Schirmer, K.

    2010-01-01

    Due to the implementation of new legislation, such as REACh, a dramatic increase of animal use for toxicity testing is expected and the search for alternatives is timely. Cell-based in vitro assays are promising alternatives. However, the behavior of chemicals in these assays is still poorly

  14. Femtosecond laser pulses for chemical-free embryonic and mesenchymal stem cell differentiation

    Science.gov (United States)

    Mthunzi, Patience; Dholakia, Kishan; Gunn-Moore, Frank

    2011-10-01

    Owing to their self renewal and pluripotency properties, stem cells can efficiently advance current therapies in tissue regeneration and/or engineering. Under appropriate culture conditions in vitro, pluripotent stem cells can be primed to differentiate into any cell type some examples including neural, cardiac and blood cells. However, there still remains a pressing necessity to answer the biological questions concerning how stem cell renewal and how differentiation programs are operated and regulated at the genetic level. In stem cell research, an urgent requirement on experimental procedures allowing non-invasive, marker-free observation of growth, proliferation and stability of living stem cells under physiological conditions exists. Femtosecond (fs) laser pulses have been reported to non-invasively deliver exogenous materials, including foreign genetic species into both multipotent and pluripotent stem cells successfully. Through this multi-photon facilitated technique, directly administering fs laser pulses onto the cell plasma membrane induces transient submicrometer holes, thereby promoting cytosolic uptake of the surrounding extracellular matter. To display a chemical-free cell transfection procedure that utilises micro-litre scale volumes of reagents, we report for the first time on 70 % transfection efficiency in ES-E14TG2a cells using the enhanced green fluorescing protein (EGFP) DNA plasmid. We also show how varying the average power output during optical transfection influences cell viability, proliferation and cytotoxicity in embryonic stem cells. The impact of utilizing objective lenses of different numerical aperture (NA) on the optical transfection efficiency in ES-E14TG2a cells is presented. Finally, we report on embryonic and mesenchymal stem cell differentiation. The produced specialized cell types could thereafter be characterized and used for cell based therapies.

  15. Identifying developmental toxicity pathways for a subset of ToxCast chemicals using human embryonic stem cells and metabolomics

    Science.gov (United States)

    Metabolomics analysis was performed on the supernatant of human embryonic stem (hES) cell cultures exposed to a blinded subset of 11 chemicals selected from the chemical library of EPA's ToxCast™ chemical screening and prioritization research project. Metabolites from hES cultur...

  16. Detection of Cell Wall Chemical Variation in Zea Mays Mutants Using Near-Infrared Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Buyck, N.; Thomas, S.

    2001-01-01

    Corn stover is regarded as the prime candidate feedstock material for commercial biomass conversion in the United States. Variations in chemical composition of Zea mays cell walls can affect biomass conversion process yields and economics. Mutant lines were constructed by activating a Mu transposon system. The cell wall chemical composition of 48 mutant families was characterized using near-infrared (NIR) spectroscopy. NIR data were analyzed using a multivariate statistical analysis technique called Principal Component Analysis (PCA). PCA of the NIR data from 349 maize leaf samples reveals 57 individuals as outliers on one or more of six Principal Components (PCs) at the 95% confidence interval. Of these, 19 individuals from 16 families are outliers on either PC3 (9% of the variation) or PC6 (1% of the variation), the two PCs that contain information about cell wall polymers. Those individuals for which altered cell wall chemistry is confirmed with wet chemical analysis will then be subjected to fermentation analysis to determine whether or not biomass conversion process kinetics, yields and/or economics are significantly affected. Those mutants that provide indications for a decrease in process cost will be pursued further to identify the gene(s) responsible for the observed changes in cell wall composition and associated changes in process economics. These genes will eventually be incorporated into maize breeding programs directed at the development of a truly dual use crop.

  17. Localized Chemical Remodeling for Live Cell Imaging of Protein-Specific Glycoform.

    Science.gov (United States)

    Hui, Jingjing; Bao, Lei; Li, Siqiao; Zhang, Yi; Feng, Yimei; Ding, Lin; Ju, Huangxian

    2017-07-03

    Live cell imaging of protein-specific glycoforms is important for the elucidation of glycosylation mechanisms and identification of disease states. The currently used metabolic oligosaccharide engineering (MOE) technology permits routinely global chemical remodeling (GCM) for carbohydrate site of interest, but can exert unnecessary whole-cell scale perturbation and generate unpredictable metabolic efficiency issue. A localized chemical remodeling (LCM) strategy for efficient and reliable access to protein-specific glycoform information is reported. The proof-of-concept protocol developed for MUC1-specific terminal galactose/N-acetylgalactosamine (Gal/GalNAc) combines affinity binding, off-on switchable catalytic activity, and proximity catalysis to create a reactive handle for bioorthogonal labeling and imaging. Noteworthy assay features associated with LCM as compared with MOE include minimum target cell perturbation, short reaction timeframe, effectiveness as a molecular ruler, and quantitative analysis capability. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Chemical communication between synthetic and natural cells: a possible experimental design.

    Directory of Open Access Journals (Sweden)

    Livia Leoni

    2013-09-01

    Full Text Available The bottom-up construction of synthetic cells is one of the most intriguing and interesting research arenas in synthetic biology. Synthetic cells are built by encapsulating biomolecules inside lipid vesicles (liposomes, allowing the synthesis of one or more functional proteins. Thanks to the in situ synthesized proteins, synthetic cells become able to perform several biomolecular functions, which can be exploited for a large variety of applications. This paves the way to several advanced uses of synthetic cells in basic science and biotechnology, thanks to their versatility, modularity, biocompatibility, and programmability. In the previous WIVACE (2012 we presented the state-of-the-art of semi-synthetic minimal cell (SSMC technology and introduced, for the first time, the idea of chemical communication between synthetic cells and natural cells. The development of a proper synthetic communication protocol should be seen as a tool for the nascent field of bio/chemical-based Information and Communication Technologies (bio-chem-ICTs and ultimately aimed at building soft-wet-micro-robots. In this contribution (WIVACE, 2013 we present a blueprint for realizing this project, and show some preliminary experimental results. We firstly discuss how our research goal (based on the natural capabilities of biological systems to manipulate chemical signals finds a proper place in the current scientific and technological contexts. Then, we shortly comment on the experimental approaches from the viewpoints of (i synthetic cell construction, and (ii bioengineering of microorganisms, providing up-to-date results from our laboratory. Finally, we shortly discuss how autopoiesis can be used as a theoretical framework for defining synthetic minimal life, minimal cognition, and as bridge between synthetic biology and artificial intelligence.

  19. High performance polymer chemical hydrogel-based electrode binder materials for direct borohydride fuel cells

    Science.gov (United States)

    Choudhury, Nurul A.; Ma, Jia; Sahai, Yogeshwar; Buchheit, Rudolph G.

    Novel, cost-effective, high-performance, and environment-friendly electrode binders, comprising polyvinyl alcohol chemical hydrogel (PCH) and chitosan chemical hydrogel (CCH), are reported for direct borohydride fuel cells (DBFCs). PCH and CCH binders-based electrodes have been fabricated using a novel, simple, cost-effective, time-effective, and environmentally benign technique. Morphologies and electrochemical performance in DBFCs of the chemical hydrogel binder-based electrodes have been compared with those of Nafion ® binder-based electrodes. Relationships between the performance of binders in DBFCs with structural features of the polymers and the polymer-based chemical hydrogels are discussed. The CCH binder exhibited better performance than a Nafion ® binder whereas the PCH binder exhibited comparable performance to Nafion ® in DBFCs operating at elevated cell temperatures. The better performance of CCH binder at higher operating cell temperatures has been ascribed to the hydrophilic nature and water retention characteristics of chitosan. DBFCs employing CCH binder-based electrodes and a Nafion ®-117 membrane as an electrolyte exhibited a maximum peak power density of about 589 mW cm -2 at 70 °C.

  20. Chemical stimulation of adherent cells by localized application of acetylcholine from a microfluidic system

    Directory of Open Access Journals (Sweden)

    Susanne Zibek

    2010-11-01

    Full Text Available Chemical stimulation of cells is inherently cell type selective in contrast to electro-stimulation. The availability of a system for localized application of minute amounts of chemical stimulants could be useful for dose related response studies to test new compounds. It could also bring forward the development of a novel type of neuroprostheses.In an experimental setup micro-droplets of an acetylcholine solution were ejected from a fluidic microsystem and applied to the bottom of a nanoporous membrane. The solution travelled through the pores to the top of the membrane on which TE671 cells were cultivated. Calcium imaging was used to visualize cellular response with temporal and spatial resolution. Experimental demonstration of chemical stimulation for both threshold gated stimulation as well as accumulated dose response was achieved by either employing acetylcholine as chemical stimulant or applying calcein uptake, respectively.Numerical modelling and simulation of transport mechanisms involved were employed to gain a theoretical understanding of the influence of pore size, concentration of stimulant and droplet volume on the spatial-temporal distribution of stimulant and on the cellular response. Diffusion, pressure driven flow and evaporation effects were taken into account. Fast stimulation kinetic is achieved with pores of 0.82 µm diameter, whereas sustained substance delivery is obtained with nanoporous membranes. In all cases threshold concentrations ranging from 0.01 to 0.015 µM acetylcholine independent of pore size were determined.

  1. Continuous, real-time bioimaging of chemical bioavailability and toxicology using autonomously bioluminescent human cell lines.

    Science.gov (United States)

    Xu, Tingting; Close, Dan M; Webb, James D; Price, Sarah L; Ripp, Steven A; Sayler, Gary S

    2013-05-29

    Bioluminescent imaging is an emerging biomedical surveillance strategy that uses external cameras to detect in vivo light generated in small animal models of human physiology or in vitro light generated in tissue culture or tissue scaffold mimics of human anatomy. The most widely utilized of reporters is the firefly luciferase (luc) gene; however, it generates light only upon addition of a chemical substrate, thus only generating intermittent single time point data snapshots. To overcome this disadvantage, we have demonstrated substrate-independent bioluminescent imaging using an optimized bacterial bioluminescence (lux) system. The lux reporter produces bioluminescence autonomously using components found naturally within the cell, thereby allowing imaging to occur continuously and in real-time over the lifetime of the host. We have validated this technology in human cells with demonstrated chemical toxicological profiling against exotoxin exposures at signal strengths comparable to existing luc systems (~1.33 × 107 photons/second). As a proof-in-principle demonstration, we have engineered breast carcinoma cells to express bioluminescence for real-time screening of endocrine disrupting chemicals and validated detection of 17β-estradiol (EC50 = ~ 10 pM). These and other applications of this new reporter technology will be discussed as potential new pathways towards improved models of target chemical bioavailability, toxicology, efficacy, and human safety.

  2. Continuous, real-time bioimaging of chemical bioavailability and toxicology using autonomously bioluminescent human cell lines

    Science.gov (United States)

    Xu, Tingting; Close, Dan M.; Webb, James D.; Price, Sarah L.; Ripp, Steven A.; Sayler, Gary S.

    2013-05-01

    Bioluminescent imaging is an emerging biomedical surveillance strategy that uses external cameras to detect in vivo light generated in small animal models of human physiology or in vitro light generated in tissue culture or tissue scaffold mimics of human anatomy. The most widely utilized of reporters is the firefly luciferase (luc) gene; however, it generates light only upon addition of a chemical substrate, thus only generating intermittent single time point data snapshots. To overcome this disadvantage, we have demonstrated substrate-independent bioluminescent imaging using an optimized bacterial bioluminescence (lux) system. The lux reporter produces bioluminescence autonomously using components found naturally within the cell, thereby allowing imaging to occur continuously and in real-time over the lifetime of the host. We have validated this technology in human cells with demonstrated chemical toxicological profiling against exotoxin exposures at signal strengths comparable to existing luc systems (~1.33 × 107 photons/second). As a proof-in-principle demonstration, we have engineered breast carcinoma cells to express bioluminescence for real-time screening of endocrine disrupting chemicals and validated detection of 17β-estradiol (EC50 = ~ 10 pM). These and other applications of this new reporter technology will be discussed as potential new pathways towards improved models of target chemical bioavailability, toxicology, efficacy, and human safety.

  3. Membrane-bound cytochrome c is an alternative electron donor for cytochrome aa3 in Nitrobacter winogradskyi.

    Science.gov (United States)

    Nomoto, T; Fukumori, Y; Yamanaka, T

    1993-07-01

    We purified membrane-bound cytochrome c-550 [cytochrome c-550(m)] to an electrophoretically homogeneous state from Nitrobacter winogradskyi. The cytochrome showed peaks at 409 and 525 nm in the oxidized form and peaks at 416, 521, and 550 nm in the reduced form. The molecular weight of the cytochrome was estimated to be 18,400 on the basis of protein and heme c contents and 18,600 by gel filtration. The N-terminal amino acid sequence of cytochrome c-550(m) was determined to be A-P-T-S-A-A-D-A-E-S-F-N-K-A-L-A-S-A-?-A-E-?-G-A-?-L-V-K-P. We previously purified soluble cytochrome c-550 cytochrome c-550(s)] from N. winogradskyi and determined its complete amino acid sequence (Y. Tanaka, Y. Fukumori, and T. Y. Yamanaka, Biochim. Biophys. Acta 707:14-20, 1982). Although the sequence of cytochrome c-550(m) was completely different from that of cytochrome c-550(s), ferrocytochrome c-550(m) was rapidly oxidized by the cytochrome c oxidase of the bacterium. Furthermore, the liposomes into which nitrite cytochrome c oxidoreductase, cytochrome c oxidase, and nitrite were incorporated showed nitrite oxidase activity in the presence of cytochrome c-550(m). These results suggest that cytochrome c-550(m) may be an alternative electron mediator between nitrite cytochrome c oxidoreductase and cytochrome c oxidase.

  4. Chemical agents and enzymes used for the extraction of gut lymphocytes influence flow cytometric detection of T cell surface markers

    NARCIS (Netherlands)

    van Damme, N.; Baeten, D.; de Vos, M.; Demetter, P.; Elewaut, D.; Mielants, H.; Verbruggen, G.; Cuvelier, C.; Veys, E. M.; de Keyser, F.

    2000-01-01

    Chemical agents (DTT, EDTA) and enzymes (collagenase, DNAse) are often used for the generation of a single cell suspension from tissue samples. In this study, flow cytometry was used to examine the effect of chemical agents and enzymes on the expression of cell membrane markers of T lymphocytes from

  5. System, device, and methods for real-time screening of live cells, biomarkers, and chemical signatures

    Energy Technology Data Exchange (ETDEWEB)

    Sundaram, S Kamakshi [Richland, WA; Riley, Brian J [West Richland, WA; Weber, Thomas J [Richland, WA; Sacksteder, Colette A [West Richland, WA; Addleman, R Shane [Benton City, WA

    2011-06-07

    An ATR-FTIR device and system are described that defect live-cell responses to stimuli and perturbations in real-time. The system and device can monitor perturbations resulting from exposures to various physical, chemical, and biological materials in real-time, as well as those sustained over a long period of time, including those associated with stimuli having unknown modes-of-action (e.g. nanoparticles). The device and system can also be used to identify specific chemical species or substances that profile cellular responses to these perturbations.

  6. Detecting infrared luminescence and non-chemical signaling of living cells: single cell mid-IR spectroscopy in cryogenic environments

    Science.gov (United States)

    Pereverzev, Sergey

    2017-02-01

    Many life-relevant interaction energies are in IR range, and it is reasonable to believe that some biochemical reactions inside cells can results in emission of IR photons. Cells can use this emission for non-chemical and non-electrical signaling. Detecting weak infrared radiation from live cells is complicated because of strong thermal radiation background and absorption of radiation by tissues. A microfluidic device with live cells inside a vacuum cryogenic environment should suppress this background, and thereby permit observation of live cell auto-luminescence or signaling in the IR regime. One can make IR-transparent windows not emitting in this range, so only the cell and a small amount of liquid around it will emit infrared radiation. Currently mid-IR spectroscopy of single cells requires the use of a synchrotron source to measure absorption or reflection spectra. Decreasing of thermal radiation background will allow absorption and reflection spectroscopy of cells without using synchrotron light. Moreover, cell auto-luminescence can be directly measured. The complete absence of thermal background radiation for cryogenically cooled samples allows the use IR photon-sensitive detectors and obtaining single molecule sensitivity in IR photo-luminescence measurements. Due to low photon energies, photo-luminescence measurements will be non-distractive for pressures samples. The technique described here is based upon US patent 9366574.

  7. Fabrication and Photovoltaic Characteristics of Coaxial Silicon Nanowire Solar Cells Prepared by Wet Chemical Etching

    Directory of Open Access Journals (Sweden)

    Chien-Wei Liu

    2012-01-01

    Full Text Available Nanostructured solar cells with coaxial p-n junction structures have strong potential to enhance the performances of the silicon-based solar cells. This study demonstrates a radial junction silicon nanowire (RJSNW solar cell that was fabricated simply and at low cost using wet chemical etching. Experimental results reveal that the reflectance of the silicon nanowires (SNWs declines as their length increases. The excellent light trapping was mainly associated with high aspect ratio of the SNW arrays. A conversion efficiency of ∼7.1% and an external quantum efficiency of ∼64.6% at 700 nm were demonstrated. Control of etching time and diffusion conditions holds great promise for the development of future RJSNW solar cells. Improving the electrode/RJSNW contact will promote the collection of carries in coaxial core-shell SNW array solar cells.

  8. Cocktail of chemical compounds robustly promoting cell reprogramming protects liver against acute injury

    Directory of Open Access Journals (Sweden)

    Yuewen Tang

    2017-02-01

    Full Text Available Abstract Tissue damage induces cells into reprogramming-like cellular state, which contributes to tissue regeneration. However, whether factors promoting the cell reprogramming favor tissue regeneration remains elusive. Here we identified combination of small chemical compounds including drug cocktails robustly promoting in vitro cell reprogramming. We then administrated the drug cocktails to mice with acute liver injuries induced by partial hepatectomy or toxic treatment. Our results demonstrated that the drug cocktails which promoted cell reprogramming in vitro improved liver regeneration and hepatic function in vivo after acute injuries. The underlying mechanism could be that expression of pluripotent genes activated after injury is further upregulated by drug cocktails. Thus our study offers proof-of-concept evidence that cocktail of clinical compounds improving cell reprogramming favors tissue recovery after acute damages, which is an attractive strategy for regenerative purpose.

  9. Manipulating mammalian cell morphologies using chemical-mechanical polished integrated circuit chips.

    Science.gov (United States)

    Moussa, Hassan I; Logan, Megan; Siow, Geoffrey C; Phann, Darron L; Rao, Zheng; Aucoin, Marc G; Tsui, Ting Y

    2017-01-01

    Tungsten chemical-mechanical polished integrated circuits were used to study the alignment and immobilization of mammalian (Vero) cells. These devices consist of blanket silicon oxide thin films embedded with micro- and nano-meter scale tungsten metal line structures on the surface. The final surfaces are extremely flat and smooth across the entire substrate, with a roughness in the order of nanometers. Vero cells were deposited on the surface and allowed to adhere. Microscopy examinations revealed that cells have a strong preference to adhere to tungsten over silicon oxide surfaces with up to 99% of cells adhering to the tungsten portion of the surface. Cells self-aligned and elongated into long threads to maximize contact with isolated tungsten lines as thin as 180 nm. The orientation of the Vero cells showed sensitivity to the tungsten line geometric parameters, such as line width and spacing. Up to 93% of cells on 10 μm wide comb structures were aligned within ± 20° of the metal line axis. In contrast, only ~22% of cells incubated on 0.18 μm comb patterned tungsten lines were oriented within the same angular interval. This phenomenon is explained using a simple model describing cellular geometry as a function of pattern width and spacing, which showed that cells will rearrange their morphology to maximize their contact to the embedded tungsten. Finally, it was discovered that the materials could be reused after cleaning the surfaces, while maintaining cell alignment capability.

  10. Establishment of the first humpback whale fibroblast cell lines and their application in chemical risk assessment

    Energy Technology Data Exchange (ETDEWEB)

    Burkard, Michael, E-mail: Michael.burkard@eawag.ch [Griffith University, Environmental Futures Research Institute, Southern Ocean Persistent Organic Pollutants Program, Brisbane, QLD (Australia); Eawag, Swiss Federal Institute of Technology, Dübendorf (Switzerland); Whitworth, Deanne [The University of Queensland, School of Veterinary Science, Gatton, QLD (Australia); Schirmer, Kristin [Eawag, Swiss Federal Institute of Technology, Dübendorf (Switzerland); ETH Zürich, Institute of Biogechemistry and Pollutant Dynamics, Zürich (Switzerland); EPF Lausanne, School of Architecture, Civil and Environmental Engineering, Lausanne (Switzerland); Nash, Susan Bengtson [Griffith University, Environmental Futures Research Institute, Southern Ocean Persistent Organic Pollutants Program, Brisbane, QLD (Australia)

    2015-10-15

    Highlights: • We established and characterised the first humpback whale fibroblast cell lines. • Cell lines have a stable karyotype with 2n = 44. • Exposure to p,p′-DDE resulted in a concentration-dependent loss of cell viability. • p,p′-DDE sensitivity differed considerably from human fibroblasts. • Exposure to a whale blubber extract showed higher sensitivity than to p,p′-DDE alone. - Abstract: This paper reports the first successful derivation and characterization of humpback whale fibroblast cell lines. Primary fibroblasts were isolated from the dermal connective tissue of skin biopsies, cultured at 37 °C and 5% CO{sub 2} in the standard mammalian medium DMEM/F12 supplemented with 10% fetal bovine serum (FBS). Of nine initial biopsies, two cell lines were established from two different animals and designated HuWa1 and HuWa2. The cells have a stable karyotype with 2n = 44, which has commonly been observed in other baleen whale species. Cells were verified as being fibroblasts based on their spindle-shaped morphology, adherence to plastic and positive immunoreaction to vimentin. Population doubling time was determined to be ∼41 h and cells were successfully cryopreserved and thawed. To date, HuWa1 cells have been propagated 30 times. Cells proliferate at the tested temperatures, 30, 33.5 and 37 °C, but show the highest rate of proliferation at 37 °C. Short-term exposure to para,para′-dichlorodiphenyldichloroethylene (p,p′-DDE), a priority compound accumulating in southern hemisphere humpback whales, resulted in a concentration-dependent loss of cell viability. The effective concentration which caused a 50% reduction in HuWa1 cell viability (EC{sub 50} value) was approximately six times greater than the EC{sub 50} value for the same chemical measured with human dermal fibroblasts. HuWa1 exposed to a natural, p,p′-DDE-containing, chemical mixture extracted from whale blubber showed distinctively higher sensitivity than to p,p′-DDE alone

  11. STUDY REGARDING THE CORELATION BETWEEN SOMATIC CELLS COUNT AND MAJOR CHEMICAL COMPOUNDS IN RAW MILK

    Directory of Open Access Journals (Sweden)

    S. ACATINCĂI

    2008-10-01

    Full Text Available This study approaches the dynamic of somatic cells number and chemical composition of milk during 13 months of control. The study also investigates the correlations between the number of somatic cells and some chemical parameters in milk. Studies were carried out on Romanian Black and White cows between March 2005 and March 2006 at the Didactical farm of the Banat University of Agricultural Sciences Timisoara. As quality indicator, the number of somatic cells has different values among the controls. Average values for the 13 months of control, with the exception of three controls, were below maximum limit admitted from 1th of January 2007 (600000 SCC/ml milk. There weren’t any significant differences for SCC between the two seasons. Chemical parameters in milk varied in close limits and the differences were not significant, with one exception for fat percent. Fat percent is higher (p<0.05 in the cold season 3.87% compared with 3.55% during the warm season. Somatic cells number is weak correlated with lactose and strong correlated with proteins.

  12. Additive mixture effects of estrogenic chemicals in human cell-based assays can be influenced by inclusion of chemicals with differing effect profiles.

    Directory of Open Access Journals (Sweden)

    Richard Mark Evans

    Full Text Available A growing body of experimental evidence indicates that the in vitro effects of mixtures of estrogenic chemicals can be well predicted from the estrogenicity of their components by the concentration addition (CA concept. However, some studies have observed small deviations from CA. Factors affecting the presence or observation of deviations could include: the type of chemical tested; number of mixture components; mixture design; and assay choice. We designed mixture experiments that address these factors, using mixtures with high numbers of components, chemicals from diverse chemical groups, assays with different in vitro endpoints and different mixture designs and ratios. Firstly, the effects of mixtures composed of up to 17 estrogenic chemicals were examined using estrogenicity assays with reporter-gene (ERLUX and cell proliferation (ESCREEN endpoints. Two mixture designs were used: 1 a 'balanced' design with components present in proportion to a common effect concentration (e.g. an EC(10 and 2 a 'non-balanced' design with components in proportion to potential human tissue concentrations. Secondly, the individual and simultaneous ability of 16 potential modulator chemicals (each with minimal estrogenicity to influence the assay outcome produced by a reference mixture of estrogenic chemicals was examined. Test chemicals included plasticizers, phthalates, metals, PCBs, phytoestrogens, PAHs, heterocyclic amines, antioxidants, UV filters, musks, PBDEs and parabens. In all the scenarios tested, the CA concept provided a good prediction of mixture effects. Modulation studies revealed that chemicals possessing minimal estrogenicity themselves could reduce (negatively modulate the effect of a mixture of estrogenic chemicals. Whether the type of modulation we observed occurs in practice most likely depends on the chemical concentrations involved, and better information is required on likely human tissue concentrations of estrogens and of potential

  13. Tracking chemical changes in a live cell: Biomedical applications of SR-FTIR spectromicroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Holman, Hoi-Ying N.; Martin, Michael C.; McKinney, Wayne R.

    2002-07-25

    Synchrotron radiation-based Fourier transform infrared (SR-FTIR) spectromicroscopy is a newly emerging bioanalytical and imaging tool. This unique technique provides mid-infrared (IR) spectra, hence chemical information, with high signal-to-noise at spatial resolutions as fine as 3 to 10 microns. Thus it enables researchers to locate, identify, and track specific chemical events within an individual living mammalian cell. Mid-IR photons are too low in energy (0.05 - 0.5 eV) to either break bonds or to cause ionization. In this review, we show that the synchrotron IR beam has no detectable effects on the short- and long-term viability, reproductive integrity, cell-cycle progression, and mitochondrial metabolism in living human cells, and produces only minimal sample heating (< 0.5 degrees C). We will then present several examples demonstrating the application potentials of SR-FTIR spectromicroscopy in biomedical research. These will include monitoring living cells progressing through the cell cycle, including death, and cells reacting to dilute concentrations of toxins.

  14. Interactions between structural and chemical biomimetism in synthetic stem cell niches.

    Science.gov (United States)

    Nava, Michele M; Raimondi, Manuela T; Credi, Caterina; De Marco, Carmela; Turri, Stefano; Cerullo, Giulio; Osellame, Roberto

    2015-01-16

    Advancements in understanding stem cell functions and differentiation are of key importance for the clinical success of stem-cell-based therapies. 3D structural niches fabricated by two-photon polymerization are a powerful platform for controlling stem cell growth and differentiation. In this paper, we investigate the possibility of further controlling stem cell fate by tuning the mechanical properties of such niches through coating with thin layers of biomimetic hyaluronan-based and gelatin-based hydrogels. We first assess the biocompatibility of chemical coatings and then study the interactions between structural and chemical biomimetism on the response of MSCs in terms of proliferation and differentiation. We observed a clear effect of the hydrogel coating on otherwise identical 3D scaffolds. In particular, in gelatin-coated niches we observed a stronger metabolic activity and commitment toward the osteo-chondral lineage with respect to hyaluronan-coated niches. Conversely, a reduction in the homing effect was observed in all the coated niches, especially in gelatin-coated niches. This study demonstrates the feasibility of controlling independently different mechanical cues, in bioengineered stem cell niches, i.e. the 3D scaffold geometry and the surface stiffness. This will allow, on the one hand, understanding their specific role in stem cell proliferation and differentiation and, on the other hand, finely tuning their synergistic effect.

  15. Global (Q)SAR models on substrates for human Cytochrome P450 3A4

    DEFF Research Database (Denmark)

    Ringsted, Tine; Nikolov, Nikolai Georgiev; Wedebye, Eva Bay

    The Cytochrome P450 (CYP) is a superfamily of enzymes which catalyze the metabolism of a wide range of endobiotics and xenobiotics. The latter category comprises drugs and about 75% of marketed drugs are metabolised by CYP enzymes. Besides drugs, CYP enzymes detoxify environmental compounds...... domain. Domain coverage of EINECS chemicals and number of predicted substrates are discussed. Reference: C.W. Yap and Y.Z. Chen, Prediction of cytochrome p450 3A4, 2D6, and 2C9 inhibitors and substrates by using support vector machines, J. Chem. Inf. Model. 45 (2005), pp. 982–992....

  16. Effect of Yeast Cell Morphology, Cell Wall Physical Structure and Chemical Composition on Patulin Adsorption.

    Science.gov (United States)

    Luo, Ying; Wang, Jianguo; Liu, Bin; Wang, Zhouli; Yuan, Yahong; Yue, Tianli

    2015-01-01

    The capability of yeast to adsorb patulin in fruit juice can aid in substantially reducing the patulin toxic effect on human health. This study aimed to investigate the capability of yeast cell morphology and cell wall internal structure and composition to adsorb patulin. To compare different yeast cell morphologies, cell wall internal structure and composition, scanning electron microscope, transmission electron microscope and ion chromatography were used. The results indicated that patulin adsorption capability of yeast was influenced by cell surface areas, volume, and cell wall thickness, as well as 1,3-β-glucan content. Among these factors, cell wall thickness and 1,3-β-glucan content serve significant functions. The investigation revealed that patulin adsorption capability was mainly affected by the three-dimensional network structure of the cell wall composed of 1,3-β-glucan. Finally, patulin adsorption in commercial kiwi fruit juice was investigated, and the results indicated that yeast cells could adsorb patulin from commercial kiwi fruit juice efficiently. This study can potentially simulate in vitro cell walls to enhance patulin adsorption capability and successfully apply to fruit juice industry.

  17. Effect of Yeast Cell Morphology, Cell Wall Physical Structure and Chemical Composition on Patulin Adsorption.

    Directory of Open Access Journals (Sweden)

    Ying Luo

    Full Text Available The capability of yeast to adsorb patulin in fruit juice can aid in substantially reducing the patulin toxic effect on human health. This study aimed to investigate the capability of yeast cell morphology and cell wall internal structure and composition to adsorb patulin. To compare different yeast cell morphologies, cell wall internal structure and composition, scanning electron microscope, transmission electron microscope and ion chromatography were used. The results indicated that patulin adsorption capability of yeast was influenced by cell surface areas, volume, and cell wall thickness, as well as 1,3-β-glucan content. Among these factors, cell wall thickness and 1,3-β-glucan content serve significant functions. The investigation revealed that patulin adsorption capability was mainly affected by the three-dimensional network structure of the cell wall composed of 1,3-β-glucan. Finally, patulin adsorption in commercial kiwi fruit juice was investigated, and the results indicated that yeast cells could adsorb patulin from commercial kiwi fruit juice efficiently. This study can potentially simulate in vitro cell walls to enhance patulin adsorption capability and successfully apply to fruit juice industry.

  18. Combined chemical and structural signals of biomaterials synergistically activate cell-cell communications for improving tissue regeneration.

    Science.gov (United States)

    Xu, Yachen; Peng, Jinliang; Dong, Xin; Xu, Yuhong; Li, Haiyan; Chang, Jiang

    2017-06-01

    Biomaterials are only used as carriers of cells in the conventional tissue engineering. Considering the multi-cell environment and active cell-biomaterial interactions in tissue regeneration process, in this study, structural signals of aligned electrospun nanofibers and chemical signals of bioglass (BG) ionic products in cell culture medium are simultaneously applied to activate fibroblast-endothelial co-cultured cells in order to obtain an improved skin tissue engineering construct. Results demonstrate that the combined biomaterial signals synergistically activate fibroblast-endothelial co-culture skin tissue engineering constructs through promotion of paracrine effects and stimulation of gap junctional communication between cells, which results in enhanced vascularization and extracellular matrix protein synthesis in the constructs. Structural signals of aligned electrospun nanofibers play an important role in stimulating both of paracrine and gap junctional communication while chemical signals of BG ionic products mainly enhance paracrine effects. In vivo experiments reveal that the activated skin tissue engineering constructs significantly enhance wound healing as compared to control. This study indicates the advantages of synergistic effects between different bioactive signals of biomaterials can be taken to activate communication between different types of cells for obtaining tissue engineering constructs with improved functions. Tissue engineering can regenerate or replace tissue or organs through combining cells, biomaterials and growth factors. Normally, for repairing a specific tissue, only one type of cells, one kind of biomaterials, and specific growth factors are used to support cell growth. In this study, we proposed a novel tissue engineering approach by simply using co-cultured cells and combined biomaterial signals. Using a skin tissue engineering model, we successfully proved that the combined biomaterial signals such as surface nanostructures

  19. Chemical coding and chemosensory properties of cholinergic brush cells in the mouse gastrointestinal and biliary tract

    Directory of Open Access Journals (Sweden)

    Burkhard eSchütz

    2015-03-01

    Full Text Available The mouse gastro-intestinal and biliary tract mucosal epithelia harbor choline acetyltransferase (ChAT-positive brush cells with taste cell-like traits. With the aid of two transgenic mouse lines that express green fluorescent protein (EGFP under the control of the ChAT promoter (EGFPChAT and by using in situ hybridization and immunohistochemistry we found that EGFPChAT cells were clustered in the epithelium lining the gastric groove. EGFPChAT cells were numerous in the gall bladder and bile duct, and found scattered as solitary cells along the small and large intestine. While all EGFPChAT cells were also ChAT-positive, expression of the high-affinity choline transporter (ChT1 was never detected. Except for the proximal colon, EGFPChAT cells also lacked detectable expression of the vesicular acetylcholine transporter (VAChT. EGFPChAT cells were found to be separate from enteroendocrine cells, however they were all immunoreactive for cytokeratin 18 (CK18, transient receptor potential melastatin-like subtype 5 channel (TRPM5, and for cyclooxygenases 1 (COX1 and 2 (COX2. The ex vivo stimulation of colonic EGFPChAT cells with the bitter substance denatonium resulted in a strong increase in intracellular calcium, while in other epithelial cells such an increase was significantly weaker and also timely delayed. Subsequent stimulation with cycloheximide was ineffective in both cell populations. Given their chemical coding and chemosensory properties, EGFPChAT brush cells thus may have integrative functions and participate in induction of protective reflexes and inflammatory events by utilizing ACh and prostaglandins for paracrine signaling.

  20. Cytochrome cbb3 of Thioalkalivibrio is a Na+-pumping cytochrome oxidase

    NARCIS (Netherlands)

    Muntyan, M.S.; Cherepanov, D.A.; Malinen, A.M.; Bloch, D.A.; Sorokin, D.Y.; Severina, I.I.; Ivashina, T.V.; Lahti, R.; Muyzer, G.; Skulachev, V.P.

    2015-01-01

    Cytochrome c oxidases (Coxs) are the basic energy transducers in the respiratory chain of the majority of aerobic organisms. Coxs studied to date are redox-driven proton-pumping enzymes belonging to one of three subfamilies: A-, B-, and C-type oxidases. The C-type oxidases (cbb3 cytochromes), which

  1. Effect of chemical mutagens and carcinogens on gene expression profiles in human TK6 cells.

    Directory of Open Access Journals (Sweden)

    Lode Godderis

    Full Text Available Characterization of toxicogenomic signatures of carcinogen exposure holds significant promise for mechanistic and predictive toxicology. In vitro transcriptomic studies allow the comparison of the response to chemicals with diverse mode of actions under controlled experimental conditions. We conducted an in vitro study in TK6 cells to characterize gene expression signatures of exposure to 15 genotoxic carcinogens frequently used in European industries. We also examined the dose-responsive changes in gene expression, and perturbation of biochemical pathways in response to these carcinogens. TK6 cells were exposed at 3 dose levels for 24 h with and without S9 human metabolic mix. Since S9 had an impact on gene expression (885 genes, we analyzed the gene expression data from cells cultures incubated with S9 and without S9 independently. The ribosome pathway was affected by all chemical-dose combinations. However in general, no similar gene expression was observed among carcinogens. Further, pathways, i.e. cell cycle, DNA repair mechanisms, RNA degradation, that were common within sets of chemical-dose combination were suggested by clustergram. Linear trends in dose-response of gene expression were observed for Trichloroethylene, Benz[a]anthracene, Epichlorohydrin, Benzene, and Hydroquinone. The significantly altered genes were involved in the regulation of (anti- apoptosis, maintenance of cell survival, tumor necrosis factor-related pathways and immune response, in agreement with several other studies. Similarly in S9+ cultures, Benz[a]pyrene, Styrene and Trichloroethylene each modified over 1000 genes at high concentrations. Our findings expand our understanding of the transcriptomic response to genotoxic carcinogens, revealing the alteration of diverse sets of genes and pathways involved in cellular homeostasis and cell cycle control.

  2. Optimizing Transfection of Primary Human Umbilical Vein Endothelial Cells Using Commercially Available Chemical Transfection Reagents

    OpenAIRE

    Hunt, Michelle A.; Currie, Margaret J.; Robinson, Bridget A.; Dachs, Gabi U.

    2010-01-01

    Primary cells, such as HUVEC, are notoriously difficult to transfect and are susceptible to the toxic effects of transfection reagents. A transfection reagent with a high transfection efficiency and low cytotoxicity was sought to retain sufficient viability of transfected HUVEC for subsequent assays. Nine chemical transfection reagents, currently commercially available, were compared for their ability to transfect HUVEC in vitro. A plasmid expressing the enhanced GFP (EGFP) was used for trans...

  3. Modelling of Physical, Chemical, and Material Properties of Solid Oxide Fuel Cells

    Directory of Open Access Journals (Sweden)

    Jakub Kupecki

    2015-01-01

    Full Text Available This paper provides a review of modelling techniques applicable for system-level studies to account for physical, chemical, and material properties of solid oxide fuel cells. Functionality of 0D to 3D models is discussed and selected examples are given. Author provides information on typical length scales in evaluation of power systems with solid oxide fuel cells. In each section, proper examples of previous studies done in the field of 0D–3D modelling are recalled and discussed.

  4. Infectious Keratitis in Limbal Stem Cell Deficiency: Stevens-Johnson Syndrome Versus Chemical Burn.

    Science.gov (United States)

    Kang, Byeong Soo; Kim, Mee Kum; Wee, Won Ryang; Oh, Joo Youn

    2016-01-01

    To investigate the incidence, clinical and microbiological characteristics, risk factors, and therapeutic outcome of infectious keratitis in patients with limbal stem cell deficiency (LSCD) related to Stevens-Johnson syndrome (SJS) and corneal chemical burn. Medical records of 90 eyes of 59 patients who were diagnosed with LSCD resulting from SJS (52 eyes of 29 patients) or corneal chemical burn (38 eyes of 30 patients) were reviewed. Infectious keratitis developed in 35% of LSCD patients with SJS (18 eyes, 14 patients) and in 18% of those with chemical burn (7 eyes, 7 patients). The development of infectious keratitis in SJS was significantly associated with the severity of chronic ocular surface complications in the cornea, conjunctiva, and eyelids and with the use of topical corticosteroids during the disease course. All cases of infectious keratitis following chemical burn occurred in patients with grade III or IV burn by Roper-Hall classification. Approximately 83% of culture-proven cases of infectious keratitis were bacterial infection, most of which (80%) were caused by Gram-positive bacteria. For resolution of infection, 17 eyes (68%) received surgery in addition to medical treatment, whereas 8 eyes (32%) received medical treatment alone. After infection resolution, the final visual acuity was decreased in 10 eyes (40%) compared with before infection. Infectious keratitis is a common complication of LSCD associated with SJS or severe chemical burn to the cornea. Despite medical and surgical treatments, the visual outcome is poor.

  5. Chemically Defined Culture and Cardiomyocyte Differentiation of Human Pluripotent Stem Cells.

    Science.gov (United States)

    Burridge, Paul W; Holmström, Alexandra; Wu, Joseph C

    2015-10-06

    Since the first discovery that human pluripotent stem cells (hPS cells) can differentiate to cardiomyocytes, efforts have been made to optimize the conditions under which this process occurs. One of the most effective methodologies to optimize this process is reductionist simplification of the medium formula, which eliminates complex animal-derived components to help reveal the precise underlying mechanisms. Here we describe our latest, cost-effective and efficient methodology for the culture of hPS cells in the pluripotent state using a modified variant of chemically defined E8 medium. We provide exact guidelines for cell handling under these conditions, including non-enzymatic EDTA passaging, which have been optimized for subsequent cardiomyocyte differentiation. We describe in depth the latest version of our monolayer chemically defined small molecule differentiation protocol, including metabolic selection-based cardiomyocyte purification and the addition of triiodothyronine to enhance cardiomyocyte maturation. Finally, we describe a method for the dissociation of hPS cell-derived cardiomyocytes, cryopreservation, and thawing. Copyright © 2015 John Wiley & Sons, Inc.

  6. Nitrobacter winogradskyi cytochrome a1c1 is an iron-sulfur molybdoenzyme having hemes a and c.

    Science.gov (United States)

    Fukuoka, M; Fukumori, Y; Yamanaka, T

    1987-09-01

    Cytochrome a1c1 (nitrite-cytochrome c oxidoreductase) purified from Nitrobacter winogradskyi (formerly N. agilis) contained molybdenum, non-heme iron, and acid-labile sulfur in addition to hemes a and c; it contained 1 mol of heme a, 4-5 g atoms of non-heme iron, 2-5 g atoms of acid-labile sulfur, and 1-2 g atoms of molybdenum per mol of heme c, but did not contain copper. The fluorescence spectra of the molybdenum cofactor derivative prepared from cytochrome a1c1 were very similar to those of the cofactor derivative from xanthine oxidase, and the aponitrate reductase of nit-1 mutant of Neurospora crassa was complemented by addition of the molybdenum cofactor derived from the cytochrome. Further, the ESR spectrum of cytochrome a1c1 was similar to that of liver sulfite oxidase. The content of cytochrome a1 in the cells cultivated with the medium in which tungsten was substituted for molybdenum markedly decreased as compared with that in the cells cultivated in the molybdenum-supplemented medium. These results indicate that cytochrome a1c1 is an iron-sulfur molybdoenzyme which contains hemes a and c.

  7. Chemical durability of Solid Oxide Fuel Cells: Influence of impurities on long-term performance

    Science.gov (United States)

    Sasaki, Kazunari; Haga, Kengo; Yoshizumi, Tomoo; Minematsu, Daisuke; Yuki, Eiji; Liu, RunRu; Uryu, Chie; Oshima, Toshihiro; Ogura, Teppei; Shiratori, Yusuke; Ito, Kohei; Koyama, Michihisa; Yokomoto, Katsumi

    Because of the fuel flexibility of Solid Oxide Fuel Cells (SOFCs), various types of fuels may be applied directly or via a simple reforming process, including hydrocarbons, alcohols, coal gas, biogas, besides hydrogen. However, various types of minor constituents in practical fuels and/or from the system components can cause chemical degradation of SOFCs, such as anode and cathode poisoning phenomena. In this study, we compare the influence of various external impurities, including sulfur, chlorine, phosphorus, boron, and siloxane for anodes, and H 2O and SO 2 for cathodes, on SOFC performance to have a general overview on long-term chemical durability of SOFCs. Chemical compatibility of Ni with foreign species has also been thermochemically considered. Using common model cells, the stability of cell voltage, electrode overpotential, and ohmic loss up to 3000 h has been experimentally examined for H 2-based fuels, for hydrocarbon-based fuels, and for partially pre-reformed CH 4-based fuels. Increase in degradation rate by impurities was verified for various operational parameters. Impurity poisoning mechanisms are discussed for each specific impurity.

  8. High-Performance Chemically Regenerative Redox Fuel Cells Using a NO3-/NO Regeneration Reaction.

    Science.gov (United States)

    Han, Sang-Beom; Kwak, Da-Hee; Park, Hyun Suk; Choi, In-Ae; Park, Jin-Young; Kim, Si-Jin; Kim, Min-Cheol; Hong, Seongho; Park, Kyung-Won

    2017-03-06

    In this study, we proposed high-performance chemically regenerative redox fuel cells (CRRFCs) using NO 3 - /NO with a nitrogen-doped carbon-felt electrode and a chemical regeneration reaction of NO to NO 3 - via O 2 . The electrochemical cell using the nitrate reduction to NO at the cathode on the carbon felt and oxidation of H 2 as a fuel at the anode showed a maximal power density of 730 mW cm -2 at 80 °C and twofold higher power density of 512 mW cm -2 at 0.8 V, than the target power density of 250 mW cm -2 at 0.8 V in the H 2 /O 2 proton exchange membrane fuel cells (PEMFCs). During the operation of the CRRFCs with the chemical regeneration reactor for 30 days, the CRRFCs maintained 60 % of the initial performance with a regeneration efficiency of about 92.9 % and immediately returned to the initial value when supplied with fresh HNO 3 . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Non-specific chemical inhibition of the Fanconi anemia pathway sensitizes cancer cells to cisplatin

    Directory of Open Access Journals (Sweden)

    Jacquemont Céline

    2012-04-01

    Full Text Available Abstract Background Platinum compounds such as cisplatin and carboplatin are DNA crosslinking agents widely used for cancer chemotherapy. However, the effectiveness of platinum compounds is often tempered by the acquisition of cellular drug resistance. Until now, no pharmacological approach has successfully overcome cisplatin resistance in cancer treatment. Since the Fanconi anemia (FA pathway is a DNA damage response pathway required for cellular resistance to DNA interstrand crosslinking agents, identification of small molecules that inhibit the FA pathway may reveal classes of chemicals that sensitize cancer cells to cisplatin. Results Through a cell-based screening assay of over 16,000 chemicals, we identified 26 small molecules that inhibit ionizing radiation and cisplatin-induced FANCD2 foci formation, a marker of FA pathway activity, in multiple human cell lines. Most of these small molecules also compromised ionizing radiation-induced RAD51 foci formation and homologous recombination repair, indicating that they are not selective toward the regulation of FANCD2. These compounds include known inhibitors of the proteasome, cathepsin B, lysosome, CHK1, HSP90, CDK and PKC, and several uncharacterized chemicals including a novel proteasome inhibitor (Chembridge compound 5929407. Isobologram analyses demonstrated that half of the identified molecules sensitized ovarian cancer cells to cisplatin. Among them, 9 demonstrated increased efficiency toward FA pathway-proficient, cisplatin-resistant ovarian cancer cells. Six small molecules, including bortezomib (proteasome inhibitor, CA-074-Me (cathepsin B inhibitor and 17-AAG (HSP90 inhibitor, synergized with cisplatin specifically in FA-proficient ovarian cancer cells (2008 + FANCF, but not in FA-deficient isogenic cells (2008. In addition, geldanamycin (HSP90 inhibitor and two CHK1 inhibitors (UCN-01 and SB218078 exhibited a significantly stronger synergism with cisplatin in FA

  10. 15N-labelling and preliminary heteronuclear NMR study of Desulfovibrio vulgaris Hildenborough cytochrome c553.

    Science.gov (United States)

    Morelli, X; Dolla, A; Toci, R; Guerlesquin, F

    1999-04-01

    When using heteronuclear NMR, 15N-labelling is necessary for structural analysis, dynamic studies and determination of complex formation. The problems that arise with isotopic labelling of metalloproteins are due to their complex maturation process, which involves a large number of factors. Cytochromes c are poorly expressed in Escherichia coli and the overexpression that is necessary for 15N-labelling, requires an investigation of the expression host and special attention to growth conditions. We have succeeded in the heterologous expression and the complete and uniform isotopic 15N-labelling of the cytochrome c553 from Desulfovibrio vulgaris Hildenborough, in a sulphate-reducing bacterium, D. desulfuricans G200, by using a growth medium combining 15N-ammonium chloride and 15N-Celtone. These conditions allowed us to obtain approximately 0.8 mg x L-1 of pure labelled cytochrome c553. 1H and 15N-assignments for both the oxidized and the reduced states of cytochrome c553 were obtained from two-dimensional heteronuclear experiments. Pseudocontact effects due to the haem Fe3+ have been analysed for the first time through 15N and 1H chemical shifts in a c-type cytochrome.

  11. In situ determination of the reduction levels of cytochromes b and c in growing bacteria : a case study with N2-fixing Azorhizobium caulinodans

    NARCIS (Netherlands)

    Pronk, A.F.; Boogerd, F C; Stoof, C.; Oltmann, L F; Stouthamer, A.H.; van Verseveld, H W

    1993-01-01

    The determination of the in situ reduction levels of cytochromes b and c in growing bacteria is achieved by coupling a chemostat with a dual wavelength spectrophotometer. Visible light absorption spectra of cytochromes present in bacterial cells actively growing in a chemostat at a specific growth

  12. Nanostructured GaAs solar cells via metal-assisted chemical etching of emitter layers.

    Science.gov (United States)

    Song, Yunwon; Choi, Keorock; Jun, Dong-Hwan; Oh, Jungwoo

    2017-10-02

    GaAs solar cells with nanostructured emitter layers were fabricated via metal-assisted chemical etching. Au nanoparticles produced via thermal treatment of Au thin films were used as etch catalysts to texture an emitter surface with nanohole structures. Epi-wafers with emitter layers 0.5, 1.0, and 1.5 um in thickness were directly textured and a window layer removal process was performed before metal catalyst deposition. A nanohole-textured emitter layer provides effective light trapping capabilities, reducing the surface reflection of a textured solar cell by 11.0%. However, because the nanostructures have high surface area to volume ratios and large numbers of defects, various photovoltaic properties were diminished by high recombination losses. Thus, we have studied the application of nanohole structures to GaAs emitter solar cells and investigated the cells' antireflection and photovoltaic properties as a function of the nanohole structure and emitter thickness. Due to decreased surface reflection and improved shunt resistance, the solar cell efficiency increased from 4.25% for non-textured solar cells to 7.15% for solar cells textured for 5 min.

  13. Differentiation of Human Embryonic Stem Cells to Regional Specific Neural Precursors in Chemically Defined Medium Conditions

    Science.gov (United States)

    Erceg, Slaven; Laínez, Sergio; Ronaghi, Mohammad; Stojkovic, Petra; Pérez-Aragó, Maria Amparo; Moreno-Manzano, Victoria; Moreno-Palanques, Rubén; Planells-Cases, Rosa; Stojkovic, Miodrag

    2008-01-01

    Background Human embryonic stem cells (hESC) provide a unique model to study early events in human development. The hESC-derived cells can potentially be used to replace or restore different tissues including neuronal that have been damaged by disease or injury. Methodology and Principal Findings The cells of two different hESC lines were converted to neural rosettes using adherent and chemically defined conditions. The progenitor cells were exposed to retinoic acid (RA) or to human recombinant basic fibroblast growth factor (bFGF) in the late phase of the rosette formation. Exposing the progenitor cells to RA suppressed differentiation to rostral forebrain dopamine neural lineage and promoted that of spinal neural tissue including motor neurons. The functional characteristics of these differentiated neuronal precursors under both, rostral (bFGF) and caudalizing (RA) signals were confirmed by patch clamp analysis. Conclusions/Significance These findings suggest that our differentiation protocol has the capacity to generate region-specific and electrophysiologically active neurons under in vitro conditions without embryoid body formation, co-culture with stromal cells and without presence of cells of mesodermal or endodermal lineages. PMID:18461168

  14. Differentiation of human embryonic stem cells to regional specific neural precursors in chemically defined medium conditions.

    Directory of Open Access Journals (Sweden)

    Slaven Erceg

    Full Text Available BACKGROUND: Human embryonic stem cells (hESC provide a unique model to study early events in human development. The hESC-derived cells can potentially be used to replace or restore different tissues including neuronal that have been damaged by disease or injury. METHODOLOGY AND PRINCIPAL FINDINGS: The cells of two different hESC lines were converted to neural rosettes using adherent and chemically defined conditions. The progenitor cells were exposed to retinoic acid (RA or to human recombinant basic fibroblast growth factor (bFGF in the late phase of the rosette formation. Exposing the progenitor cells to RA suppressed differentiation to rostral forebrain dopamine neural lineage and promoted that of spinal neural tissue including motor neurons. The functional characteristics of these differentiated neuronal precursors under both, rostral (bFGF and caudalizing (RA signals were confirmed by patch clamp analysis. CONCLUSIONS/SIGNIFICANCE: These findings suggest that our differentiation protocol has the capacity to generate region-specific and electrophysiologically active neurons under in vitro conditions without embryoid body formation, co-culture with stromal cells and without presence of cells of mesodermal or endodermal lineages.

  15. Alkaline anion exchange membrane fuel cells for cogeneration of electricity and valuable chemicals

    Science.gov (United States)

    Pan, Z. F.; Chen, R.; An, L.; Li, Y. S.

    2017-10-01

    Alkaline anion exchange membrane fuel cells (AAEMFCs) have received ever-increasing attentions due to the enhanced electrochemical kinetics and the absence of precious metal electrocatalysts, and thus great progress has been made in recent years. The alkaline anion exchange membrane based direct alcohol fuel cells, one type of alkaline anion exchange membrane fuel cells utilizing liquid alcohols as fuel that can be obtained from renewable biomass feedstocks, is another attractive point due to its ability to provide electricity with cogeneration of valuable chemicals. Significant development has been made to improve the selectivity towards high added-value chemicals and power output in the past few years. This review article provides a general description of this emerging technology, including fuel-cell setup and potential reaction routes, summarizes the products, performance, and system designs, as well as introduces the application of this concept in the removal of heavy-metal ions from the industrial wastewater. In addition, the remaining challenges and perspectives are also highlighted.

  16. Fluorinated carboxylic membranes deposited by plasma enhanced chemical vapour deposition for fuel cell applications

    Science.gov (United States)

    Thery, J.; Martin, S.; Faucheux, V.; Le Van Jodin, L.; Truffier-Boutry, D.; Martinent, A.; Laurent, J.-Y.

    Among the fuel cell technologies, the polymer electrolyte membrane fuel cells (PEMFCs) are particularly promising because they are energy-efficient, clean, and fuel-flexible (i.e., can use hydrogen or methanol). The great majority of PEM fuel cells rely on a polymer electrolyte from the family of perfluorosulfonic acid membranes, nevertheless alternative materials are currently being developed, mainly to offer the alternative workout techniques which are required for the portable energy sources. Plasma polymerization represents a good solution, as it offers the possibility to deposit thin layer with an accurate and homogeneous thickness, even on 3D surfaces. In this paper, we present the results for the growth of proton conductive fluoro carboxylic membranes elaborated by plasma enhanced chemical vapour deposition. These membranes present conductivity values of the same order than the one of Nafion ®. The properties of the membrane, such as the chemical composition, the ionic conductivity, the swelling behaviour and the permeability were correlated to the plasma process parameters. The membranes were integrated in fuel cells on porous substrates and we present here the results regarding the barrier effect and the power output. Barrier effect similar to those of 40 μm Nafion ® layers was reached for 10 μm thick carboxylic membranes. Power outputs around 3 mW cm -2 were measured. We discuss the results regarding the gas barrier effect and the power outputs.

  17. Cannabinoids and Cytochrome P450 Interactions.

    Science.gov (United States)

    Zendulka, Ondřej; Dovrtělová, Gabriela; Nosková, Kristýna; Turjap, Miroslav; Šulcová, Alexandra; Hanuš, Lumír; Juřica, Jan

    2016-01-01

    This review consists of three parts, representing three different possibilities of interactions between cannabinoid receptor ligands of both exogenous and endogenous origin and cytochrome P450 enzymes (CYPs). The first part deals with cannabinoids as CYP substrates, the second summarizes current knowledge on the influence of various cannabinoids on the metabolic activity of CYP, and the third outline a possible involvement of the endocannabinoid system and cannabinoid ligands in the regulation of CYP liver activity. We performed a structured search of bibliographic and drug databases for peer-reviewed literature using focused review questions. Biotransformation via a hydrolytic pathway is the major route of endocannabinoid metabolism and the deactivation of substrates is characteristic, in contrast to the minor oxidative pathway via CYP involved in the bioactivation reactions. Phytocannabinoids are extensively metabolized by CYPs. The enzymes CYP2C9, CYP2C19, and CYP3A4 catalyze most of their hydroxylations. Similarly, CYP represents a major metabolic pathway for both synthetic cannabinoids used therapeutically and drugs that are abused. In vitro experiments document the mostly CYP inhibitory activity of the major phytocannabinoids, with cannabidiol as the most potent inhibitor of many CYPs. The drug-drug interactions between cannabinoids and various drugs at the CYP level are reported, but their clinical relevance remains unclear. The direct activation/inhibition of nuclear receptors in the liver cells by cannabinoids may result in a change of CYP expression and activity. Finally, we hypothesize the interplay of central cannabinoid receptors with numerous nervous systems, resulting in a hormone-mediated signal towards nuclear receptors in hepatocytes.

  18. Recent advances in cytochrome c biosensing technologies.

    Science.gov (United States)

    Manickam, Pandiaraj; Kaushik, Ajeet; Karunakaran, Chandran; Bhansali, Shekhar

    2017-01-15

    This review is an attempt, for the first time, to describe advancements in sensing technology for cytochrome c (cyt c) detection, at point-of-care (POC) application. Cyt c, a heme containing metalloprotein is located in the intermembrane space of mitochondria and released into bloodstream during pathological conditions. The release of cyt c from mitochondria is a key initiative step in the activation of cell death pathways. Circulating cyt c levels represents a novel in-vivo marker of mitochondrial injury after resuscitation from heart failure and chemotherapy. Thus, cyt c detection is not only serving as an apoptosis biomarker, but also is of great importance to understand certain diseases at cellular level. Various existing techniques such as enzyme-linked immunosorbent assays (ELISA), Western blot, high performance liquid chromatography (HPLC), spectrophotometry and flow cytometry have been used to estimate cyt c. However, the implementation of these techniques at POC application is limited due to longer analysis time, expensive instruments and expertise needed for operation. To overcome these challenges, significant efforts are being made to develop electrochemical biosensing technologies for fast, accurate, selective, and sensitive detection of cyt c. Presented review describes the cutting edge technologies available in the laboratories to detect cyt c. The recent advancements in designing and development of electrochemical cyt c biosensors for the quantification of cyt c are also discussed. This review also highlights the POC cyt c biosensors developed recently, that would prove of interest to biologist and therapist to get real time informatics needed to evaluate death process, diseases progression, therapeutics and processes related with mitochondrial injury. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Chemical Synthesis of Oligosaccharides related to the Cell Walls of Plants and Algae

    DEFF Research Database (Denmark)

    Kinnaert, Christine; Daugaard, Mathilde; Nami, Faranak

    2017-01-01

    Plant cell walls are composed of an intricate network of polysaccharides and proteins that varies during the developmental stages of the cell. This makes it very challenging to address the functions of individual wall components in cells, especially for highly complex glycans. Fortunately...... in good quantities and with high purity. This review contains an overview of those plant and algal polysaccharides, which have been elucidated to date. The majority of the content is devoted to detailed summaries of the chemical syntheses of oligosaccharide fragments of cellulose, hemicellulose, pectin......, and arabinogalactans, as well as glycans unique to algae. Representative synthetic routes within each class are discussed in detail and the progress in carbohydrate chemistry over recent decades is highlighted....

  20. DMSO Chemically Alters Cell Membranes to Slow Exocytosis and Increase the Fraction of Partial Transmitter Released.

    Science.gov (United States)

    Majdi, Soodabeh; Najafinobar, Neda; Dunevall, Johan; Lovric, Jelena; Ewing, Andrew G

    2017-10-05

    Dimethyl sulfoxide (DMSO) is frequently used as a solvent in biological studies and as a vehicle for drug therapy; but the side effects of DMSO, especially on the cell environment, are not well understood, and controls with DMSO are not neutral at higher concentrations. Herein, electrochemical measurement techniques are applied to show that DMSO increases exocytotic neurotransmitter release, while leaving vesicular contents unchanged. In addition, the kinetics of release from DMSO-treated cells are faster than that of untreated ones. The results suggest that DMSO has a significant influence on the chemistry of the cell membrane, leading to alteration of exocytosis. A speculative chemical mechanism of the effect on the fusion pore during exocytosis is presented. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. The application of Dow Chemical's perfluorinated membranes in proton-exchange membrane fuel cells

    Science.gov (United States)

    Eisman, G. A.

    1989-01-01

    Dow Chemical's research activities in fuel cells revolve around the development of perfluorosulfonic acid membranes useful as the proton transport medium and separator. Some of the performance characteristics which are typical for such membranes are outlined. The results of tests utilizing a new experimental membrane useful in proton-exchange membrane fuel cells are presented. The high voltage at low current densities can lead to higher system efficiencies while, at the same time, not sacrificing other critical properties pertinent to membrane fuel cell operation. A series of tests to determine response times indicated that on-off cycles are on the order of 80 milliseconds to reach 90 percent of full power. The IR free voltage at 100 amps/sq ft was determined and the results indicating a membrane/electrode package resistance to be .15 ohm-sq cm at 100 amps/sq ft.

  2. Chemically tuned anode with tailored aqueous hydrocarbon binder for direct methanol fuel cells.

    Science.gov (United States)

    Lee, Chang Hyun; Lee, So Young; Lee, Young Moo; McGrath, James E

    2009-07-21

    An anode for direct methanol fuel cells was chemically tuned by tailoring an aqueous hydrocarbon catalyst (SPI-BT) binder instead of using a conventional perfluorinated sulfonic acid ionomer (PFSI). SPI-BT designed in triethylamine salt form showed lower proton conductivity than PFSI, but it was stable in the catalyst ink forming the aqueous colloids. The aqueous colloidal particle size of SPI-BT was much smaller than that of PFSI. The small SPI-BT colloidal particles contributed to forming small catalyst agglomerates and simultaneously reducing their pore volume. Consequently, the high filling level of binders in the pores, where Pt-Ru catalysts are mainly located on the wall and physically interconnected, resulted in increased electrochemical active surface area of the anode, leading to high catalyst utilization. In addition, the chemical affinity between the SPI-BT binder and the membrane material derived from their similar chemical structure induced a stable interface on the membrane-electrode assembly (MEA) and showed low electric resistance. Upon adding SPI-BT, the synergistic effect of high catalyst utilization, improved mass transfer behavior to Pt-Ru catalyst, and low interfacial resistance of MEA became greater than the influence of reduced proton conductivity in the electrochemical performance of single cells. The electrochemical performance of MEAs with SPI-BT anode was enhanced to almost the same degree or somewhat higher than that with PFSI at 90 degrees C.

  3. Xenobiotic metabolism capacities of human skin in comparison with a 3D epidermis model and keratinocyte-based cell culture as in vitro alternatives for chemical testing: activating enzymes (Phase I).

    Science.gov (United States)

    Götz, Christine; Pfeiffer, Roland; Tigges, Julia; Blatz, Veronika; Jäckh, Christine; Freytag, Eva-Maria; Fabian, Eric; Landsiedel, Robert; Merk, Hans F; Krutmann, Jean; Edwards, Robert J; Pease, Camilla; Goebel, Carsten; Hewitt, Nicola; Fritsche, Ellen

    2012-05-01

    Skin is important for the absorption and metabolism of exposed chemicals such as cosmetics or pharmaceuticals. The Seventh Amendment to the EU Cosmetics Directive prohibits the use of animals for cosmetic testing for certain endpoints, such as genotoxicity; therefore, there is an urgent need to understand the xenobiotic metabolizing capacities of human skin and to compare these activities with reconstructed 3D skin models developed to replace animal testing. We have measured Phase I enzyme activities of cytochrome P450 (CYP) and cyclooxygenase (COX) in ex vivo human skin, the 3D skin model EpiDerm™ (EPI-200), immortalized keratinocyte-based cell lines and primary normal human epidermal keratinocytes. Our data demonstrate that basal CYP enzyme activities are very low in whole human skin and EPI-200 as well as keratinocytes. In addition, activities in monolayer cells differed from organotypic tissues after induction. COX activity was similar in skin, EPI-200 and NHEK cells, but was significantly lower in immortalized keratinocytes. Hence, the 3D model EPI-200 might represent a more suitable model for dermatotoxicological studies. Altogether, these data help to better understand skin metabolism and expand the knowledge of in vitro alternatives used for dermatotoxicity testing. © 2012 John Wiley & Sons A/S.

  4. Cell lines from grc congenic strains of rats having different susceptibilities to chemical carcinogens.

    Science.gov (United States)

    Lu, D; Kunz, H W; Melhem, M F; Gill, T J

    1993-09-01

    The growth and reproduction complex (grc-) strains of rats have a 70-kilobase deletion in the major histocompatibility complex (MHC)-linked grc-G/C region that is associated with embryonic death, developmental defects, and an increased susceptibility to chemical carcinogens. To study further the effects associated with the deletion, fibroblastic cell lines from grc-, grc+, and grc+/- rat embryos were developed: BIL-derived cell lines are congenic for the MHC and grc, whereas R16-derived cell lines are congenic for the grc alone. In early passages, all cell lines expressed the MHC class I antigen RT1.A, had a diploid chromosome number, and did not display anchorage-independent growth or in vivo tumorigenicity. The grc- cells [median population doubling time (PDT), 47 h] grew more slowly than the grc+ (PDT, 30.5 h) and grc+/- (PDT, 33 h) cells. All cells underwent crisis, but the crisis stage began earlier and lasted longer in the grc- cells. The established grc- cell lines (PDT, 32.5 h) grew faster than the grc+ (PDT, 48.5 h) and grc+/- (PDT, 54 h) cell lines. Two of the three BIL-derived grc- lines that survived crisis became anchorage independent in tissue culture and tumorigenic in histocompatible F1 rats (highly malignant fibrosarcomas) at passages 33 and 48, respectively; by contrast, none of the R16-derived grc- cell lines transformed. None of 8 grc+ or 8 grc+/- cell lines that survived crisis displayed anchorage-independent growth or tumorigenicity under the same conditions up to passage 50. All of the established cell lines, including the two tumorigenic ones, expressed MHC class I antigens. Southern and Northern blot analyses of BIL-derived cell lines before and after crisis showed that they all constitutively expressed H-ras and Rb and that no cell line showed rearrangement, amplification, or overexpression of c-myc, H-ras, Rb, and p53 either before or after crisis. These observations indicate that: (a) the homozygous grc- deletion is necessary but not

  5. Detecting recalcitrant organic chemicals in water with microbial fuel cells and artificial neural networks.

    Science.gov (United States)

    King, Scott T; Sylvander, Marc; Kheperu, Mekhakhem; Racz, LeeAnn; Harper, Willie F

    2014-11-01

    This study integrates artificial neural network (ANN) processing with microbial fuel cell (MFC)-based biosensing in the detection of three organic pollutants: aldicarb, dimethyl-methylphosphonate (DMMP), and bisphenol-A (BPA). Overall, the use of the ANN proved to be more reliable than direct correlations for the determination of both chemical concentration and type. The ANN output matched the appropriate chemical concentration and type for three different concentrations and throughout a wide range of stepwise tests. Additionally, chemicals dissolved in the acetate-based feed medium (FM) were accurately identified by the ANN even though the acetate masked the pollutants' effects on electrical current. The ANN also accurately revealed the identity of chemical mixtures. This study is the first to incorporate ANN modeling with MFC-based biosensing for the detection and quantification of organic pollutants that are not readily biodegradable. Furthermore, this work provides insight into the flexibility of MFC-based biosensing as it pertains to limits of detection and its applicability to scenarios where mixtures of pollutants and unique solvents are involved. This research effort is expected to serve as a guide for future MFC-based biosensing efforts. Published by Elsevier B.V.

  6. Systematic development and optimization of chemically defined medium supporting high cell density growth of Bacillus coagulans.

    Science.gov (United States)

    Chen, Yu; Dong, Fengqing; Wang, Yonghong

    2016-09-01

    With determined components and experimental reducibility, the chemically defined medium (CDM) and the minimal chemically defined medium (MCDM) are used in many metabolism and regulation studies. This research aimed to develop the chemically defined medium supporting high cell density growth of Bacillus coagulans, which is a promising producer of lactic acid and other bio-chemicals. In this study, a systematic methodology combining the experimental technique with flux balance analysis (FBA) was proposed to design and simplify a CDM. The single omission technique and single addition technique were employed to determine the essential and stimulatory compounds, before the optimization of their concentrations by the statistical method. In addition, to improve the growth rationally, in silico omission and addition were performed by FBA based on the construction of a medium-size metabolic model of B. coagulans 36D1. Thus, CDMs were developed to obtain considerable biomass production of at least five B. coagulans strains, in which two model strains B. coagulans 36D1 and ATCC 7050 were involved.

  7. Chemically dispersed oil is cytotoxic and genotoxic to sperm whale skin cells.

    Science.gov (United States)

    Wise, Catherine F; Wise, James T F; Wise, Sandra S; Wise, John Pierce

    2017-11-08

    Two major oil crises in United States history, the 1989 Exxon-Valdez oil spill in Alaska and the 2010 Deepwater Horizon Oil Rig explosion in the Gulf of Mexico, drew attention to the need for toxicological experiments on oil and chemically dispersed oil. We are still learning the effects these spills had on wildlife. However, little data is known about the toxicity of these substances in marine mammals. The objective of this study is to determine the toxicity of Alaskan oil, as well as chemically dispersed oil. Oil experiments were performed using the water accommodated fraction of Alaskan oil (WAF) and the chemically enhanced water accommodated fraction of Alaskan oil (CEWAF). The Alaskan WAF is not cytotoxic to sperm whale skin cells though it did induce chromosome damage; S9-mediated metabolism did not affect the cytotoxicity of WAF but did increase the levels of chromosome damage. Alaskan CEWAF is more cytotoxic and genotoxic than the WAF; S9 mediated metabolism increased both cytotoxicity and genotoxicity of CEWAF. Analysis of the PAH content of Alaskan WAF and CEWAF revealed a forty-fold increase in the total levels of PAHs in CEWAF compared to WAF. These findings show that chemically dispersed oil leads to higher levels of PAH exposure which are more toxic and likely to lead to longer and more persistent health effects. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. A polydimethylsiloxane-polycarbonate hybrid microfluidic device capable of generating perpendicular chemical and oxygen gradients for cell culture studies.

    Science.gov (United States)

    Chang, Chia-Wen; Cheng, Yung-Ju; Tu, Melissa; Chen, Ying-Hua; Peng, Chien-Chung; Liao, Wei-Hao; Tung, Yi-Chung

    2014-10-07

    This paper reports a polydimethylsiloxane-polycarbonate (PDMS-PC) hybrid microfluidic device capable of performing cell culture under combinations of chemical and oxygen gradients. The microfluidic device is constructed of two PDMS layers with microfluidic channel patterns separated by a thin PDMS membrane. The top layer contains an embedded PC film and a serpentine channel for a spatially confined oxygen scavenging chemical reaction to generate an oxygen gradient in the bottom layer for cell culture. Using the chemical reaction method, the device can be operated with a small amount of chemicals, without bulky gas cylinders and sophisticated flow control schemes. Furthermore, it can be directly used in conventional incubators with syringe pumps to simplify the system setup. The bottom layer contains arrangements of serpentine channels for chemical gradient generation and a cell culture chamber in the downstream. The generated chemical and oxygen gradients are experimentally characterized using a fluorescein solution and an oxygen-sensitive fluorescent dye, respectively. For demonstration, a 48 hour cell-based drug test and a cell migration assay using human lung adenocarcinoma epithelial cells (A549) are conducted under various combinations of the chemical and oxygen gradients in the experiments. The drug testing results show an increase in A549 cell apoptosis due to the hypoxia-activated cytotoxicity of tirapazamine (TPZ) and also suggest great cell compatibility and gradient controllability of the device. In addition, the A549 cell migration assay results demonstrate an aerotactic behavior of the A549 cells and suggest that the oxygen gradient plays an essential role in guiding cell migration. The migration results, under combinations of chemokine and oxygen gradients, cannot be simply superposed with single gradient results. The device is promising to advance the control of in vitro microenvironments, to better study cellular responses under various

  9. Complex bud architecture and cell-specific chemical patterns enable supercooling of Picea abies bud primordia.

    Science.gov (United States)

    Kuprian, Edith; Munkler, Caspar; Resnyak, Anna; Zimmermann, Sonja; Tuong, Tan D; Gierlinger, Notburga; Müller, Thomas; Livingston, David P; Neuner, Gilbert

    2017-12-01

    Bud primordia of Picea abies, despite a frozen shoot, stay ice free down to -50 °C by a mechanism termed supercooling whose biophysical and biochemical requirements are poorly understood. Bud architecture was assessed by 3D-reconstruction, supercooling and freezing patterns by infrared video thermography, freeze dehydration and extraorgan freezing by water potential measurements, and cell-specific chemical patterns by Raman microscopy and mass spectrometry imaging. A bowl-like ice barrier tissue insulates primordia from entrance by intrinsic ice. Water repellent and densely packed bud scales prevent extrinsic ice penetration. At -18 °C, break-down of supercooling was triggered by intrinsic ice nucleators whereas the ice barrier remained active. Temperature-dependent freeze dehydration (-0.1 MPa K-1 ) caused accumulation of extraorgan ice masses that by rupture of the shoot, pith tissue are accommodated in large voids. The barrier tissue has exceptionally pectin-rich cell walls and intercellular spaces, and the cell lumina were lined or filled with proteins, especially near the primordium. Primordial cells close to the barrier accumulate di, tri and tetrasaccharides. Bud architecture efficiently prevents ice penetration, but ice nucleators become active inside the primordium below a temperature threshold. Biochemical patterns indicate a complex cellular interplay enabling supercooling and the necessity for cell-specific biochemical analysis. © 2017 The Authors Plant, Cell & Environment Published by John Wiley & Sons Ltd.

  10. Chemical Analysis of Morphological Changes in Lysophosphatidic Acid-Treated Ovarian Cancer Cells.

    Science.gov (United States)

    Bailey, Karen A; Klymenko, Yuliya; Feist, Peter E; Hummon, Amanda B; Stack, M Sharon; Schultz, Zachary D

    2017-11-10

    Ovarian cancer (OvCa) cells are reported to undergo biochemical changes at the cell surface in response to treatment with lysophosphatidic acid (LPA). Here we use scanning electron microscopy (SEM) and multiplex coherent anti-Stokes Raman scattering (CARS) imaging via supercontinuum excitation to probe morphological changes that result from LPA treatment. SEM images show distinct shedding of microvilli-like features upon treatment with LPA. Analysis of multiplex CARS images can distinguish between molecular components, such as lipids and proteins. Our results indicate that OvCa429 and SKOV3ip epithelial ovarian cancer cells undergo similar morphological and chemical responses to treatment with LPA. The microvilli-like structures on the surface of multicellular aggregates (MCAs) are removed by treatment with LPA. The CARS analysis shows a distinct decrease in protein and increase in lipid composition on the surface of LPA-treated cells. Importantly, the CARS signals from cellular sheddings from MCAs with LPA treatment are consistent with cleavage of proteins originally present. Mass spectrometry on the cellular sheddings show that a large number of proteins, both membrane and intracellular, are present. An increased number of peptides are detected for the mesenchymal cell line relative to the epithelial cell indicating a differential response to LPA treatment with cancer progression.

  11. Release of chemical transmitters from cell bodies and dendrites of nerve cells.

    Science.gov (United States)

    De-Miguel, Francisco F; Nicholls, John G

    2015-07-05

    Papers in this issue concern extrasynaptic transmission, namely release of signalling molecules by exocytosis or diffusion from neuronal cell bodies, dendrites, axons and glia. Problems discussed concern the molecules, their secretion and importance for normal function and disease. Molecules secreted extrasynaptically include transmitters, peptides, hormones and nitric oxide. For extrasynaptic secretion, trains of action potentials are required, and the time course of release is slower than at synapses. Questions arise concerning the mechanism of extrasynaptic secretion: how does it differ from the release observed at synaptic terminals and gland cells? What kinds of vesicles take part? Is release accomplished through calcium entry, SNAP and SNARE proteins? A clear difference is in the role of molecules released synaptically and extrasynaptically. After extrasynaptic release, molecules reach distant as well as nearby cells, and thereby produce long-lasting changes over large volumes of brain. Such changes can affect circuits for motor performance and mood states. An example with clinical relevance is dyskinesia of patients treated with l-DOPA for Parkinson's disease. Extrasynaptically released transmitters also evoke responses in glial cells, which in turn release molecules that cause local vasodilatation and enhanced circulation in regions of the brain that are active. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  12. Chemical Characterization and in Vitro Cytotoxicity on Squamous Cell Carcinoma Cells of Carica papaya Leaf Extracts.

    Science.gov (United States)

    Nguyen, Thao T; Parat, Marie-Odile; Hodson, Mark P; Pan, Jenny; Shaw, Paul N; Hewavitharana, Amitha K

    2015-12-24

    In traditional medicine, Carica papaya leaf has been used for a wide range of therapeutic applications including skin diseases and cancer. In this study, we investigated the in vitro cytotoxicity of aqueous and ethanolic extracts of Carica papaya leaves on the human oral squamous cell carcinoma SCC25 cell line in parallel with non-cancerous human keratinocyte HaCaT cells. Two out of four extracts showed a significantly selective effect towards the cancer cells and were found to contain high levels of phenolic and flavonoid compounds. The chromatographic and mass spectrometric profiles of the extracts obtained with Ultra High Performance Liquid Chromatography-Quadrupole Time of Flight-Mass Spectrometry were used to tentatively identify the bioactive compounds using comparative analysis. The principal compounds identified were flavonoids or flavonoid glycosides, particularly compounds from the kaempferol and quercetin families, of which several have previously been reported to possess anticancer activities. These results confirm that papaya leaf is a potential source of anticancer compounds and warrant further scientific investigation to validate the traditional use of papaya leaf to treat cancer.

  13. Chemical Characterization and in Vitro Cytotoxicity on Squamous Cell Carcinoma Cells of Carica Papaya Leaf Extracts

    Directory of Open Access Journals (Sweden)

    Thao T. Nguyen

    2015-12-01

    Full Text Available In traditional medicine, Carica papaya leaf has been used for a wide range of therapeutic applications including skin diseases and cancer. In this study, we investigated the in vitro cytotoxicity of aqueous and ethanolic extracts of Carica papaya leaves on the human oral squamous cell carcinoma SCC25 cell line in parallel with non-cancerous human keratinocyte HaCaT cells. Two out of four extracts showed a significantly selective effect towards the cancer cells and were found to contain high levels of phenolic and flavonoid compounds. The chromatographic and mass spectrometric profiles of the extracts obtained with Ultra High Performance Liquid Chromatography-Quadrupole Time of Flight-Mass Spectrometry were used to tentatively identify the bioactive compounds using comparative analysis. The principal compounds identified were flavonoids or flavonoid glycosides, particularly compounds from the kaempferol and quercetin families, of which several have previously been reported to possess anticancer activities. These results confirm that papaya leaf is a potential source of anticancer compounds and warrant further scientific investigation to validate the traditional use of papaya leaf to treat cancer.

  14. Energy and chemicals from the selective electrooxidation of renewable diols by organometallic fuel cells.

    Science.gov (United States)

    Bellini, Marco; Bevilacqua, Manuela; Filippi, Jonathan; Lavacchi, Alessandro; Marchionni, Andrea; Miller, Hamish A; Oberhauser, Werner; Vizza, Francesco; Annen, Samuel P; Grützmacher, H

    2014-09-01

    Organometallic fuel cells catalyze the selective electrooxidation of renewable diols, simultaneously providing high power densities and chemicals of industrial importance. It is shown that the unique organometallic complex [Rh(OTf)(trop2NH)(PPh3)] employed as molecular active site in an anode of an OMFC selectively oxidizes a number of renewable diols, such as ethylene glycol , 1,2-propanediol (1,2-P), 1,3-propanediol (1,3-P), and 1,4-butanediol (1,4-B) to their corresponding mono-carboxylates. The electrochemical performance of this molecular catalyst is discussed, with the aim to achieve cogeneration of electricity and valuable chemicals in a highly selective electrooxidation from diol precursors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Slurry-Based Chemical Hydrogen Storage Systems for Automotive Fuel Cell Applications

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, Kriston P.; Semelsberger, Troy; Simmons, Kevin L.; Van Hassel, Bart A.

    2014-05-30

    In this paper, the system designs for hydrogen storage using chemical hydrogen materials in an 80 kWe fuel cell, light-duty vehicle are described. Ammonia borane and alane are used for these designs to represent the general classes of exothermic and endothermic materials. The designs are then compared to the USDRIVE/DOE developed set of system level targets for on-board storage. While most of the DOE targets are predicted to be achieved based on the modeling, the system gravimetric and volumetric densities were more challenging and became the focus of this work. The resulting system evaluation determined that the slurry is majority of the system mass. Only modest reductions in the system mass can be expected with improvements in the balance of plant components. Most of the gravimetric improvements will require developing materials with higher inherent storage capacity or by increasing the solids loading of the chemical hydrogen storage material in the slurry.

  16. DWPF nitric-glycolic flowsheet chemical process cell chemistry. Part 1

    Energy Technology Data Exchange (ETDEWEB)

    Zamecnik, J. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Edwards, T. B. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-02-01

    The conversions of nitrite to nitrate, the destruction of glycolate, and the conversion of glycolate to formate and oxalate were modeled for the Nitric-Glycolic flowsheet using data from Chemical Process Cell (CPC) simulant runs conducted by SRNL from 2011 to 2015. The goal of this work was to develop empirical correlations for these variables versus measureable variables from the chemical process so that these quantities could be predicted a-priori from the sludge composition and measurable processing variables. The need for these predictions arises from the need to predict the REDuction/OXidation (REDOX) state of the glass from the Defense Waste Processing Facility (DWPF) melter. This report summarizes the initial work on these correlations based on the aforementioned data. Further refinement of the models as additional data is collected is recommended.

  17. Fabrication and Analysis of Chemically-Derived Graphene/Pyramidal Si Heterojunction Solar Cells

    Science.gov (United States)

    Lee, Wen-Chieh; Tsai, Meng-Lin; Chen, You-Ling; Tu, Wei-Chen

    2017-04-01

    In the study, the chemically-derived reduced graphene oxide flakes on the pyramidal Si substrate to construct the heterojunction solar cells via simple spin-coating process have been presented. The total reflectance of chemically-derived graphene on pyramidal Si is ~12% at the wavelength of 550 nm which is remarkably reduced compared with that of reduced graphene oxide on planar Si. By modifying the density and distribution of reduced graphene oxide flakes on Si, the power conversion efficiency of 5.20% is achieved. Additionally, the simulated absorbance of different-thick graphene is implemented to optimize the performance of graphene/pyramidal Si devices. The fabrication technique for rGO-based devices has the merits of simplicity, large scale, high throughput and low cost, which is a new starting point in the direction of graphene-based material for the applications of next generation optoelectronics.

  18. PROLIFERATION AS A KEY EVENT IN DEVELOPMENTAL TOXICITY: "CHEMICAL SCREENING IN HUMAN NEURAL STEM CELLS USING HIGH CONTENT IMAGING

    Science.gov (United States)

    New toxicity testing approaches will rely on in vitro assays to assess chemical effects at the cellular and molecular level. Cell proliferation is imperative to normal development, and chemical disruption of this process can be detrimental to the organism. As part of an effort to...

  19. Influence of membrane type, current and potential on the response to chemical toxicants of a microbial fuel cell based biosensor

    NARCIS (Netherlands)

    Stein, N.E.; Hamelers, H.V.M.; Buisman, C.J.N.

    2012-01-01

    Drinking water free of chemical toxicants is important for people's health. A microbial fuel cell based biosensor can be used to detect the presence of toxic chemicals. The sensitivity of this type of biosensor for nickel was investigated. There was no delay in the response of the sensor and the

  20. Expanding Thermal Plasma Chemical Vapour Deposition of ZnO:Al Layers for CIGS Solar Cells

    Directory of Open Access Journals (Sweden)

    K. Sharma

    2014-01-01

    Full Text Available Aluminium-doped zinc oxide (ZnO:Al grown by expanding thermal plasma chemical vapour deposition (ETP-CVD has demonstrated excellent electrical and optical properties, which make it an attractive candidate as a transparent conductive oxide for photovoltaic applications. However, when depositing ZnO:Al on CIGS solar cell stacks, one should be aware that high substrate temperature processing (i.e., >200°C can damage the crucial underlying layers/interfaces (such as CIGS/CdS and CdS/i-ZnO. In this paper, the potential of adopting ETP-CVD ZnO:Al in CIGS solar cells is assessed: the effect of substrate temperature during film deposition on both the electrical properties of the ZnO:Al and the eventual performance of the CIGS solar cells was investigated. For ZnO:Al films grown using the high thermal budget (HTB condition, lower resistivities, ρ, were achievable (~5 × 10−4 Ω·cm than those grown using the low thermal budget (LTB conditions (~2 × 10−3 Ω·cm, whereas higher CIGS conversion efficiencies were obtained for the LTB condition (up to 10.9% than for the HTB condition (up to 9.0%. Whereas such temperature-dependence of CIGS device parameters has previously been linked with chemical migration between individual layers, we demonstrate that in this case it is primarily attributed to the prevalence of shunt currents.

  1. Bioinformatic identification of cytochrome b5 homologues from the parasitic nematode Ascaris suum and the free-living nematode Caenorhabditis elegans highlights the crucial role of A. suum adult-specific secretory cytochrome b₅ in parasitic adaptation.

    Science.gov (United States)

    Takamiya, Shinzaburo; Hashimoto, Muneaki; Mita, Toshihiro; Yokota, Takehiro; Nakajima, Yoshitaka; Yamakura, Fumiyuki; Sugio, Shigetoshi; Fujimura, Tsutomu; Ueno, Takashi; Yamasaki, Hiroshi

    2016-04-01

    We previously reported that adult Ascaris suum possesses NADH-metmyoglobin and NADH-methaemoglobin reductase systems that are located in the cells of the body wall and in the extracellular perienteric fluid, respectively, which helps them adapt to environmental hypoxia by recovering the differential functions of myoglobin and haemoglobin. A. suum cytochrome b5, an adult-specific secretory protein and an essential component of the NADH-metmyo (haemo) globin reductase system, has been extensively studied, and its unique nature has been determined. However, the relationship between A. suum cytochrome b5 and the canonical cytochrome b5 proteins, from the free-living nematode Caenorhabditis elegans is unclear. Here, we have characterised four cytochrome b5-like proteins from C. elegans (accession numbers: CAB01732, CCD68984, CAJ58492, and CAA98498) and three from A. suum (accession numbers: ADY48796, ADY46277, and ADY48338) and compared them with A. suum cytochrome b5 in silico. Bioinformatic and molecular analyses showed that CAA98498 from C. elegans is equivalent of A. suum cytochrome b5, which was not expressed as a mature mRNA. Further, the CAA98498 possessed no secretory signal peptide, which occurs in A. suum cytochrome b5 precursor. These results suggest that this free-living nematode does not need a haemoprotein such as the A. suum cytochrome b5 and highlight the crucial function of this A. suum adult-specific secretory cytochrome b5 in parasitic adaptation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  2. New insight into the mechanism of mitochondrial cytochrome c function.

    Directory of Open Access Journals (Sweden)

    Rita V Chertkova

    Full Text Available We investigate functional role of the P76GTKMIFA83 fragment of the primary structure of cytochrome c. Based on the data obtained by the analysis of informational structure (ANIS, we propose a model of functioning of cytochrome c. According to this model, conformational rearrangements of the P76GTKMIFA83 loop fragment have a significant effect on conformational mobility of the heme. It is suggested that the conformational mobility of cytochrome c heme is responsible for its optimal orientation with respect to electron donor and acceptor within ubiquinol-cytochrome c oxidoreductase (complex III and cytochrome c oxidase (complex IV, respectively, thus, ensuring electron transfer from complex III to complex IV. To validate the model, we design several mutant variants of horse cytochrome c with multiple substitutions of amino acid residues in the P76GTKMIFA83 sequence that reduce its ability to undergo conformational rearrangements. With this, we study the succinate-cytochrome c reductase and cytochrome c oxidase activities of rat liver mitoplasts in the presence of mutant variants of cytochrome c. The electron transport activity of the mutant variants decreases to different extent. Resonance Raman spectroscopy (RRS and surface-enhanced Raman spectroscopy (SERS data demonstrate, that all mutant cytochromes possess heme with the higher degree of ruffling deformation, than that of the wild-type (WT cytochrome c. The increase in the ruffled deformation of the heme of oxidized cytochromes correlated with the decrease in the electron transport rate of ubiquinol-cytochrome c reductase (complex III. Besides, all mutant cytochromes have lower mobility of the pyrrol rings and methine bridges, than WT cytochrome c. We show that a decrease in electron transport activity in the mutant variants correlates with conformational changes and reduced mobility of heme porphyrin. This points to a significant role of the P76GTKMIFA83 fragment in the electron transport

  3. Biodehalogenation: reactions of cytochrome P-450 with polyhalomethanes.

    Science.gov (United States)

    Castro, C E; Wade, R S; Belser, N O

    1985-01-01

    The products, stoichiometry, and kinetics of the oxidation of the enzyme cytochrome P-450 cam by five polyhalomethanes and chloronitromethane are described. The reactivity of the enzyme is compared with that of deuteroheme and with the enzyme in its native cell, Pseudomonas putida (PpG-786). In all cases, the reaction entails hydrogenolysis of the carbon-halogen bond: 2FeIIP + RCXn----2FeIIIP + RCHXn-1 (P = porphyrin or P-450 cam in vitro and in vivo). Trichloronitromethane was the fastest reacting substrate, and chloroform was the slowest. The results establish that P. putida is a valid whole cell model for the reductase activity of the P-450 complement in these reactions. The reactions of cytochrome P-450 with polyhaloalkanes proceed in a manner quite analogous to other iron(II) proteins in the G conformation. The chemistry observed for the enzyme parallels that of its iron(II) porphyrin active site. Iron-bonded carbenes are not intermediates, and hydrolytically stable iron alkyls are not products of these reactions.

  4. Machine learning prediction of cancer cell sensitivity to drugs based on genomic and chemical properties.

    Directory of Open Access Journals (Sweden)

    Michael P Menden

    Full Text Available Predicting the response of a specific cancer to a therapy is a major goal in modern oncology that should ultimately lead to a personalised treatment. High-throughput screenings of potentially active compounds against a panel of genomically heterogeneous cancer cell lines have unveiled multiple relationships between genomic alterations and drug responses. Various computational approaches have been proposed to predict sensitivity based on genomic features, while others have used the chemical properties of the drugs to ascertain their effect. In an effort to integrate these complementary approaches, we developed machine learning models to predict the response of cancer cell lines to drug treatment, quantified through IC₅₀ values, based on both the genomic features of the cell lines and the chemical properties of the considered drugs. Models predicted IC₅₀ values in a 8-fold cross-validation and an independent blind test with coefficient of determination R² of 0.72 and 0.64 respectively. Furthermore, models were able to predict with comparable accuracy (R² of 0.61 IC50s of cell lines from a tissue not used in the training stage. Our in silico models can be used to optimise the experimental design of drug-cell screenings by estimating a large proportion of missing IC₅₀ values rather than experimentally measuring them. The implications of our results go beyond virtual drug screening design: potentially thousands of drugs could be probed in silico to systematically test their potential efficacy as anti-tumour agents based on their structure, thus providing a computational framework to identify new drug repositioning opportunities as well as ultimately be useful for personalized medicine by linking the genomic traits of patients to drug sensitivity.

  5. Indium sulfide thin films as window layer in chemically deposited solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lugo-Loredo, S. [Universidad Autónoma de Nuevo León, UANL, Fac. de Ciencias Químicas, Av. Universidad S/N Ciudad Universitaria San Nicolás de Los Garza Nuevo León, C.P. 66451 (Mexico); Peña-Méndez, Y., E-mail: yolapm@gmail.com [Universidad Autónoma de Nuevo León, UANL, Fac. de Ciencias Químicas, Av. Universidad S/N Ciudad Universitaria San Nicolás de Los Garza Nuevo León, C.P. 66451 (Mexico); Calixto-Rodriguez, M. [Universidad Tecnológica Emiliano Zapata del Estado de Morelos, Av. Universidad Tecnológica No. 1, C.P. 62760 Emiliano Zapata, Morelos (Mexico); Messina-Fernández, S. [Universidad Autónoma de Nayarit, Ciudad de la Cultura “Amado Nervo” S/N, C.P. 63190 Tepic, Nayarit (Mexico); Alvarez-Gallegos, A. [Universidad Autónoma del Estado de Morelos, Centro de Investigación en Ingeniería y Ciencias Aplicadas, Av. Universidad 1001, C.P. 62209, Cuernavaca Morelos (Mexico); Vázquez-Dimas, A.; Hernández-García, T. [Universidad Autónoma de Nuevo León, UANL, Fac. de Ciencias Químicas, Av. Universidad S/N Ciudad Universitaria San Nicolás de Los Garza Nuevo León, C.P. 66451 (Mexico)

    2014-01-01

    Indium sulfide (In{sub 2}S{sub 3}) thin films have been synthesized by chemical bath deposition technique onto glass substrates using In(NO{sub 3}){sub 3} as indium precursor and thioacetamide as sulfur source. X-ray diffraction studies have shown that the crystalline state of the as-prepared and the annealed films is β-In{sub 2}S{sub 3}. Optical band gap values between 2.27 and 2.41 eV were obtained for these films. The In{sub 2}S{sub 3} thin films are photosensitive with an electrical conductivity value in the range of 10{sup −3}–10{sup −7} (Ω cm){sup −1}, depending on the film preparation conditions. We have demonstrated that the In{sub 2}S{sub 3} thin films obtained in this work are suitable candidates to be used as window layer in thin film solar cells. These films were integrated in SnO{sub 2}:F/In{sub 2}S{sub 3}/Sb{sub 2}S{sub 3}/PbS/C–Ag solar cell structures, which showed an open circuit voltage of 630 mV and a short circuit current density of 0.6 mA/cm{sup 2}. - Highlights: • In{sub 2}S{sub 3} thin films were deposited using the Chemical Bath Deposition technique. • A direct energy band gap between 2.41 to 2.27 eV was evaluated for the In{sub 2}S{sub 3} films. • We made chemically deposited solar cells using the In{sub 2}S{sub 3} thin films.

  6. Rastrelliger systematics inferred from mitochondrial cytochrome b ...

    African Journals Online (AJOL)

    The fish genus Rastrelliger is composed of three morphologically recognized species; Rastrelliger kanagurta, Rastrelliger brachysoma and Rastrelliger faughni. In this study, cytochrome b gene sequencing was applied to address the systematics and phylogenetic relationships of these species. In agreement with previous ...

  7. Prediction of cytochrome P450 mediated metabolism

    DEFF Research Database (Denmark)

    Olsen, Lars; Oostenbrink, Chris; Jørgensen, Flemming Steen

    2015-01-01

    Cytochrome P450 enzymes (CYPs) form one of the most important enzyme families involved in the metabolism of xenobiotics. CYPs comprise many isoforms, which catalyze a wide variety of reactions, and potentially, a large number of different metabolites can be formed. However, it is often hard...

  8. Structure-based optimisation of non-steroidal cytochrome P450 17A1 inhibitors

    DEFF Research Database (Denmark)

    Larsen, Morten; Hansen, Cecilie Hurup; Rasmussen, Tobias B.

    2017-01-01

    Five new non-steroidal inhibitors for cytochrome P450 17A1 (CYP17A1) were identified by structure-based optimisation from a recently identified selective CYP17A1 inhibitor. The compounds are nanomolar inhibitors of steroidogenesis measured in recombinant CYP17A1 and in H295R cells....

  9. Protein Phosphorylation and Prevention of Cytochrome Oxidase Inhibition by ATP: Coupled Mechanisms of Energy Metabolism Regulation

    National Research Council Canada - National Science Library

    Acin-Perez, Rebeca; Gatti, Domenico L; Bai, Yidong; Manfredi, Giovanni

    2011-01-01

    ... cytochrome oxidase (COX), the terminal enzyme of the electron transfer chain (ETC), as one of its targets ( Acin-Perez et al., 2009a, 2009b ). COX translocates protons across the inner mitochondrial membrane, contributing to the proton electrochemical gradient used by the ATP synthase to generate ATP. In living cells, COX is a pacemaker ...

  10. A stable human progesterone receptor expressing HeLa reporter cell line as a tool in chemical evaluation at the different cell-cycle phases.

    Science.gov (United States)

    Mori, Tetsushi; Murata, Mai; Yoshino, Tomoko; Nakasono, Satoshi; Saito, Fumiyo; Takeyama, Haruko; Matsunaga, Tadashi

    2009-04-25

    Specific molecular events, characteristic of each cell-cycle phase may have direct effect to the functionality of nuclear receptors. Based on this understanding, the evaluation of lipophilic chemicals at the different cell-cycle phases is significant and should be considered. In order to achieve the aim of performing large-scale dose-response analysis on the effects of lipophilic chemicals at the different cell-cycle phases, a stable, sensitive and highly selective human progesterone receptor (hPR) expressing HeLa reporter cell line, hPRLuc-20, was established. Upon the establishment of the hPRLuc-20 cells, they were synchronized to the G(1), S and G(2) phases and treated with progesterone (PROG) and promegestone (R5020). The cells successfully showed that at the different cell-cycle phase, both agonists resulted in different cellular responses. The differences in response supports that hPR expressed within the hPRLuc-20 cells do respond in a cell-cycle dependent manner, thus showing the cells' compatibility in large-scale dose-response analyses of chemicals. It is hopeful that the advanced application of the hPRLuc-20 cells could contribute to provide fundamental hints to further understand the function of hPR, and provide key observations to elucidate the nature of these chemicals with hPR, its corresponding co-regulators and transcription factors.

  11. Expanding thermal plasma chemical vapour deposition of ZnO:Al layers for CIGS solar cells

    OpenAIRE

    Sharma, K; Williams, B. L.; Mittal, A.; Knoops, H. C. M.; Kniknie, B.J.; Bakker, N J; Kessels, W. M. M.; Schropp, R.E.I.; Creatore, M.

    2014-01-01

    Aluminium-doped zinc oxide (ZnO:Al) grown by expanding thermal plasma chemical vapour deposition (ETP-CVD) has demonstrated excellent electrical and optical properties, which make it an attractive candidate as a transparent conductive oxide for photovoltaic applications. However, when depositing ZnO:Al on CIGS solar cell stacks, one should be aware that high substrate temperature processing (i.e., >200°C) can damage the crucial underlying layers/interfaces (such as CIGS/CdS and CdS/i-ZnO). In...

  12. Chemical etching of zinc oxide for thin-film silicon solar cells.

    Science.gov (United States)

    Hüpkes, Jürgen; Owen, Jorj I; Pust, Sascha E; Bunte, Eerke

    2012-01-16

    Chemical etching is widely applied to texture the surface of sputter-deposited zinc oxide for light scattering in thin-film silicon solar cells. Based on experimental findings from the literature and our own results we propose a model that explains the etching behavior of ZnO depending on the structural material properties and etching agent. All grain boundaries are prone to be etched to a certain threshold, that is defined by the deposition conditions and etching solution. Additionally, several approaches to modify the etching behavior through special preparation and etching steps are provided. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Are The Chemical Bonding Interactions in Halide Perovskite Solar Cells Cooperative?

    Science.gov (United States)

    Varadwaj, Pradeep; Varadwaj, Arpita; Yamashita, Koichi

    Designing novel photo-sensitive and -responsive light harvesting solar cell materials is an important area of nanoscience and technologies mainly because these can transform the light energy directly or indirectly into electricity. Examples of a few of them, inter alia, include dye-sensitized solar cells, organic solar cells and halide perovskite solar cells. Methylammonium lead iodide (CH3NH3PbI3) organic-inorganic hybrid perovskite is one of the highly valued photocatalysts reported till date, which is comparable in its strength with the inorganic cesium lead iodide (CsPbI3) perovskite solar cell especially for energy conversion. The study thus has focused on the fundamental understanding of the geometrical, electronic and energetic properties of the CH3NH3PbI3 and CsPbI3 nanoclusters, obtained using density functional theory calculations. The main aim towards this end was to uncover the consequences of additivity, or non-additive cooperative binding, in the intermolecular chemical bonding interactions examined for these nanoclusters. The results obtained are compared with the current state-of-the-art, and will be discussed in detail.

  14. SGNS2: a compartmentalized stochastic chemical kinetics simulator for dynamic cell populations.

    Science.gov (United States)

    Lloyd-Price, Jason; Gupta, Abhishekh; Ribeiro, Andre S

    2012-11-15

    Cell growth and division affect the kinetics of internal cellular processes and the phenotype diversity of cell populations. Since the effects are complex, e.g. different cellular components are partitioned differently in cell division, to account for them in silico, one needs to simulate these processes in great detail. We present SGNS2, a simulator of chemical reaction systems according to the Stochastic Simulation Algorithm with multi-delayed reactions within hierarchical, interlinked compartments which can be created, destroyed and divided at runtime. In division, molecules are randomly segregated into the daughter cells following a specified distribution corresponding to one of several partitioning schemes, applicable on a per-molecule-type basis. We exemplify its use with six models including a stochastic model of the disposal mechanism of unwanted protein aggregates in Escherichia coli, a model of phenotypic diversity in populations with different levels of synchrony, a model of a bacteriophage's infection of a cell population and a model of prokaryotic gene expression at the nucleotide and codon levels. SGNS2, instructions and examples available at www.cs.tut.fi/~lloydpri/sgns2/ (open source under New BSD license). jason.lloyd-price@tut.fi. Supplementary data are available at Bioinformatics online.

  15. Initiated chemical vapor deposition of thermoresponsive poly(N-vinylcaprolactam) thin films for cell sheet engineering.

    Science.gov (United States)

    Lee, Bora; Jiao, Alex; Yu, Seungjung; You, Jae Bem; Kim, Deok-Ho; Im, Sung Gap

    2013-08-01

    Poly(N-vinylcaprolactam) (PNVCL) is a thermoresponsive polymer known to be nontoxic, water soluble and biocompatible. Here, PNVCL homopolymer was successfully synthesized for the first time by use of a one-step vapor-phase process, termed initiated chemical vapor deposition (iCVD). Fourier transform infrared spectroscopy results showed that radical polymerization took place from N-vinylcaprolactam monomers without damaging the functional caprolactam ring. A sharp lower critical solution temperature transition was observed at 31°C from the iCVD poly(N-vinylcaprolactam) (PNVCL) film. The thermoresponsive PNVCL surface exhibited a hydrophilic/hydrophobic alteration with external temperature change, which enabled the thermally modulated attachment and detachment of cells. The conformal coverage of PNVCL film on various substrates with complex topography, including fabrics and nanopatterns, was successfully demonstrated, which can further be utilized to fabricate cell sheets with aligned cell morphology. The advantage of this system is that cells cultured on such thermoresponsive surfaces could be recovered as an intact cell sheet by simply lowering the temperature, eliminating the need for conventional enzymatic treatments. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  16. Cell morphology of extrusion foamed poly(lactic acid) using endothermic chemical foaming agent.

    Science.gov (United States)

    Matuana, Laurent M; Faruk, Omar; Diaz, Carlos A

    2009-12-01

    Poly(lactic acid) (PLA) was foamed with an endothermic chemical foaming agent (CFA) through an extrusion process. The effects of polymer melt flow index, CFA content, and processing speed on the cellular structures, void fraction, and cell-population density of foamed PLA were investigated. The apparent melt viscosity of PLA was measured to understand the effect of melt index on the cell morphology of foamed PLA samples. The void fraction was strongly dependent on the PLA melt index. It increased with increasing melt index, reaching a maximum value, after which it decreased. Melt index showed no significant effect on the cell-population density of foamed samples within the narrow range studied. A gas containment limit was observed in PLA foamed with CFA. Both the void fraction and cell-population density increased with an initial increase in CFA content, reached a maximum value, and then decreased as CFA content continued to increase. The processing speed also affected the morphology of PLA foams. The void fraction reached a maximum value as the extruder's screw speed increased to 40 rpm and a further increase in the processing speed tended to reduce the void fraction of foamed samples. By contrast, cell-population density increased one order of magnitude by increasing the screw speed from 20 to 120 rpm. The experimental results indicate that a homogeneous and finer cellular morphology could be successfully achieved in PLA foamed in an extrusion process with a proper combination of polymer melt flow index, CFA content, and processing speed.

  17. Chemical composition of Schinus molle essential oil and its cytotoxic activity on tumour cell lines.

    Science.gov (United States)

    Díaz, Cecilia; Quesada, Silvia; Brenes, Oscar; Aguilar, Gilda; Cicció, José F

    2008-01-01

    The leaf essential oil hydrodistilled from Schinus molle grown in Costa Rica was characterised in terms of its chemical composition, antioxidant activity, ability to induce cytotoxicity and the mechanism of cell death involved in the process. As a result, 42 constituents, accounting for 97.2% of the total oil, were identified. The major constituents of the oil were beta-pinene and alpha-pinene. The antioxidant activity showed an IC(50) of 36.3 microg mL(-1). The essential oil was cytotoxic in several cell lines, showing that it is more effective on breast carcinoma and leukemic cell lines. The LD(50) for cytotoxicity at 48 h in K562 corresponded to 78.7 microg mL(-1), which was very similar to the LD(50) obtained when apoptosis was measured. The essential oil did not induce significant necrosis up to 200 microg mL(-1), which together with the former results indicate that apoptosis is the main mechanism of toxicity induced by S. molle essential oil in this cell line. In conclusion, the essential oil tested was weak antioxidant and induced cytotoxicity in different cell types by a mechanism related to apoptosis. It would be interesting to elucidate the role that different components of the oil play in the effect observed here, since some of them could have potential anti-tumoural effects, either alone or in combination.

  18. Sensitivity of different cytotoxic responses of Vero cells exposed to organic chemical pollutants and their reliability in the bio-toxicity test of trace chemical pollutants.

    Science.gov (United States)

    Liao, Ting-Ting; Shi, Yan-Ling; Jia, Jian-Wei; Wang, Lei

    2010-06-01

    To find a sensitive cytotoxic response to reflect the bio-toxicity of trace organic pollutants, the sensitivity and reliability of morphological change and proliferation inhibition of Vero cells exposed to 2, 4, 6-trichlorophenol (TCP) and the leachate from products related to drinking water (PRDW) were compared, and the mechanism of the morphological change in Vero cells exposed to chemical pollutants was studied. Vero cells were treated by different concentration of TCP and the leachate from PRDW. Methylthiazol-2-yl-2, 5-diphenyl tetrazolium bromide (MTT) assay was carried out for proliferation inhibition. Bioluminescence method was carried out as another method to test the toxicity of TCP. Flow Cytometry assay was used to test cell Apoptosis and damage of cell-membrane. 0.25 mg/L TCP had an effect on cell morphology, and the proportion of morphologically changed cells increased with increasing TCP concentration. At low TCP concentrations, inhibition of cell proliferation did not seem to correlate to TCP concentration, and was negative when TCP concentration was cells increased with extracting temperature, but the inhibition of cell proliferation failed to reflect the correlation between extracting temperature and proliferation inhibition of Vero cells. Although the Sensitivity of bioluminescence method seems to be similar to morphological change in Vero cells, the bacterial in this method is not homologous enough with human body cells to reflect the toxicity to human body. These imply cell morphological change is a more sensitive and reliable method to reflect bio-toxicity of organic pollutants than proliferation inhibition. Flow cytometry analysis and cell rejuvenation experiments indicated cell membrane damage, which results in cell morphological change, was an early and sensitive cytotoxic response comparing with necrosis. These results indicated that the cell membrane toxicity represented by morphological changes is a more sensitive and reliable method to

  19. Effects of Self-Assembled Monolayers with Different Chemical Groups on Ovarian Cancer Cell Line Behavior In Vitro

    Directory of Open Access Journals (Sweden)

    Jie Li

    2015-01-01

    Full Text Available In addition to serving as a physical support, the extracellular matrix (ECM actively influences cell behavior. However, the definitive effects of different chemical structures present in the ECM on cell behavior remain obscure. The current study aimed to investigate the effects of different chemical structures present in the ECM on cellular physiology using the ovarian cancer cell line SKOV-3 as a model. Self-assembled monolayers (SAMs with different chemical modifications, including methyl (-CH3, hydroxyl (-OH, amino (-NH2, carboxyl (-COOH, and mercapto (-SH groups, were used as microenvironmental models to explore the effects of different structures on SKOV-3 cells. The cell morphology, cell adhesion, cytotoxicity, and functional alterations in cancer cells cultured on different SAMs were analyzed. The results showed that SKOV-3 cells cultured on -NH2 surfaces exhibited the largest contact area, whereas those on -CH3 surfaces exhibited the smallest contact area and mostly rounded morphologies. Additionally, -NH2 and -COOH promoted cell proliferation and adhesion, whereas CH3 inhibited adhesion, leading to G1 arrest during the cell cycle and resulting in cell apoptosis. This study may provide useful information for reconstruction of the ECM and for controlling cell behavior in related areas of study.

  20. Chemical and biological properties of hot water extract from delipidated cells of Mycobacterium bovis strain BCG.

    Science.gov (United States)

    Sato, H; Yokosawa, A; Arai, H; Nagai, H; Kurita, K

    1976-09-01

    A water-soluble fraction was isolated from delipidated cells of Mycobacterium bovis strain BCG by extraction with hot water. Chemical analyses revealed that the above fraction presumably consisted of a peptidoglycan containing 5-10% of nucleic acids. When it was injected into guinea pigs with Freund's incomplete adjuvant plus egg white albumin as antigen, an increase of circulating antibody was observed as shown by the augmented titers of precipitin and hemagglutinin. The results of skin test and corneal reaction indicated that the fraction mentioned above induced delayed hypersensitivity to egg white albumin. Footpad reaction in mice demonstrated that the above fraction induced delayed hypersensitivity to sheep red blood cells. It was confirmed in addition that the adjuvant activity of this fraction was not due to the presence of nucleic acids. This adjuvant-active fraction was designated as HSA (hot-water soluble adjuvant.

  1. Softlithography in Chemical Sensing – Analytes from Molecules to Cells

    Directory of Open Access Journals (Sweden)

    Anton Leidl

    2005-12-01

    Full Text Available Imprinting is a flexible and straightforward technique to generate selective sensormaterials e.g. for mass-sensitive detection. Inherently, the strategy suits both molecularanalytes and entire micro organisms or cells. Imprinted polyurethanes e.g. are capable ofdistinguishing the different xylene isomers with very appreciable selectivity factors.Combining imprinted titanates with surface transverse wave resonators (STW leads to apowerful tool for detecting engine oil degradation, which is an excellent example foroxidative deterioration processes in a highly complex matrix. Surface imprints withgeometrically equal cavities exhibit clear chemical selectivity, as can e.g. be seen throughthe example of different human rhinovirus (HRV serotypes. Another example is a bloodgroup-selective sensor prepared by templating with erythrocyte ghosts. Both the bloodgroupA and B imprinted material selectively distinguish between blood groups A, B and O,whereas no difference in sensor signal has been observed for AB, where both blood groupantigen types are present on the cell surface.

  2. DNA-protein cross-links produced by various chemicals in cultured human lymphoma cells.

    Science.gov (United States)

    Costa, M; Zhitkovich, A; Harris, M; Paustenbach, D; Gargas, M

    1997-04-11

    Chemicals such as cis-platinum, formaldehyde, chromate, copper, and certain arsenic compounds have been shown to produce DNA-protein cross-links in human in vitro cell systems at high doses, such as those in the cytotoxic range. Thus far there have only been a limited number of other chemicals evaluated for their ability to produce cross-links. The purpose of the work described here was to evaluate whether select industrial chemicals can form DNA-protein cross-links in human cells in vitro. We evaluated acetaldehyde, acrolein, diepoxybutane, paraformaldehyde, 2-furaldehyde, propionaldehyde, chloroacetaldehyde, sodium arsenite, and a deodorant tablet [Mega Blue; hazardous component listed as tris(hydroxymethyl)nitromethane]. Short- and long-term cytotoxicity was evaluated and used to select appropriate doses for in vitro testing. DNA-protein cross-linking was evaluated at no fewer than three doses and two cell lysate washing temperatures (45 and 65 degrees C) in Epstein-Barr virus (EBV) human Burkitt's lymphoma cells. The two washing temperatures were used to assess the heat stability of the DNA-protein cross-link, 2-Furaldehyde, acetaldehyde, and propionaldehyde produced statistically significant increases in DNA-protein cross-links at washing temperatures of 45 degrees C, but not 65 degrees C, and at or above concentrations of 5, 17.5, and 75 mM, respectively. Acrolein, diepoxybutane, paraformaldehyde, and Mega Blue produced statistically significant increases in DNA-protein cross-links washed at 45 and 65 degrees C at or above concentrations of 0.15 mM, 12.5 mM, 0.003%, and 0.1%, respectively. Sodium arsenite and chloroacetaldehyde did not produce significantly increased DNA-protein cross-links at either temperature nor at any dose tested. Excluding paraformaldehyde and 2-furaldehyde treatments, significant increases in DNA-protein cross-links were observed only at doses that resulted in complete cell death within 4 d following dosing. This work demonstrates that

  3. Improved performance of the microbial electrolysis desalination and chemical-production cell using the stack structure.

    Science.gov (United States)

    Chen, Shanshan; Liu, Guangli; Zhang, Renduo; Qin, Bangyu; Luo, Yong; Hou, Yanping

    2012-07-01

    The microbial electrolysis desalination and chemical-production cell (MEDCC) is a device to desalinate seawater, and produce acid and alkali. The objective of this study was to enhance the desalination and chemical-production performance of the MEDCC using two types of stack structure. Experiments were conducted with different membrane spacings, numbers of desalination chambers and applied voltages. Results showed that the stack construction in the MEDCC enhanced the desalination and chemical-production rates. The maximal desalination rate of 0.58 ± 0.02 mmol/h, which was 43% higher than that in the MEDCC, was achieved in the four-desalination-chamber MEDCC with the AEM-CEM stack structure and the membrane spacing of 1.5mm. The maximal acid- and alkali-production rates of 0.079 ± 0.006 and 0.13 ± 0.02 mmol/h, which were 46% and 8% higher than that in the MEDCC, respectively, were achieved in the two-desalination-chamber MEDCC with the BPM-AEM-CEM stack structure and the membrane spacing of 3mm. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. The production of ammonia by multiheme cytochromes C.

    Science.gov (United States)

    Simon, Jörg; Kroneck, Peter M H

    2014-01-01

    The global biogeochemical nitrogen cycle is essential for life on Earth. Many of the underlying biotic reactions are catalyzed by a multitude of prokaryotic and eukaryotic life forms whereas others are exclusively carried out by microorganisms. The last century has seen the rise of a dramatic imbalance in the global nitrogen cycle due to human behavior that was mainly caused by the invention of the Haber-Bosch process. Its main product, ammonia, is a chemically reactive and biotically favorable form of bound nitrogen. The anthropogenic supply of reduced nitrogen to the biosphere in the form of ammonia, for example during environmental fertilization, livestock farming, and industrial processes, is mandatory in feeding an increasing world population. In this chapter, environmental ammonia pollution is linked to the activity of microbial metalloenzymes involved in respiratory energy metabolism and bioenergetics. Ammonia-producing multiheme cytochromes c are discussed as paradigm enzymes.

  5. Structural Models for Cytochrome P450�Mediated Catalysis

    Directory of Open Access Journals (Sweden)

    David F.V. Lewis

    2003-01-01

    Full Text Available This review focuses on the structural models for cytochrome P450 that are improving our knowledge and understanding of the P450 catalytic cycle, and the way in which substrates bind to the enzyme leading to catalytic conversion and subsequent formation of mono-oxygenated metabolites. Various stages in the P450 reaction cycle have now been investigated using X-ray crystallography and electronic structure calculations, whereas homology modelling of mammalian P450s is currently revealing important aspects of pharmaceutical and other xenobiotic metabolism mediated by P450 involvement. These features are explored in the current review on P450-based catalysis, which emphasises the importance of structural modelling to our understanding of this enzyme's function. In addition, the results of various QSAR analyses on series of chemicals, which are metabolised via P450 enzymes, are presented such that the importance of electronic and other structural factors in explaining variations in rates of metabolism can be appreciated.

  6. Prediction of cytochrome p450 mediated metabolism of designer drugs.

    Science.gov (United States)

    Nielsen, Line Marie; Linnet, Kristian; Olsen, Lars; Rydberg, Patrik

    2014-01-01

    The analysis of designer drugs in human plasma is highly complex, as most of these drugs are metabolized quickly, and often into multiple products. For novel designer drugs, it is common that reference compounds for these metabolites are unavailable at the time of analysis. Hence, the usage of in silico procedures to accurately predict the chemical structures of these metabolites would be very useful. In this study, the differences between several methods for prediction of site of metabolism for cytochrome P450 mediated drug metabolism are described, and their prediction accuracies are analyzed on a set of designer drugs. It is found that ligand-based methods, which are simpler and faster, are better than or at least as good as much more complex structure-based methods.

  7. Cell wall chemical characteristics of whole-crop cereal silages harvested at three maturity stages.

    Science.gov (United States)

    Wallsten, Johanna; Hatfield, Ronald

    2016-08-01

    In cooler climates such as found in Scandinavian countries cereals are important feedstuffs for ruminants often ensiled as whole-crop cereal silages (WCCS) to preserve nutrients. Animal performance varies with the type of cereal forage and stage of cereal development being ensiled. Cell wall isolation and analysis was undertaken to determine differences among cereal silages harvested at different stages of maturity. A set of 27 WCCS samples of barley, wheat and oats harvested at heading, early milk, and dough stages of maturity were analyzed for cell wall (CW) composition and compared to previous NDF analyses. Total CW concentrations of the WCCS were higher than the NDF concentration. The lignin concentration was higher (P oats (111 g kg(-1) DM) than in barley (88 g kg(-1) DM) and wheat (91 g kg(-1) DM). Ferulates (ester and ether linked) ranged from 12.2 to 14.9 g kg(-1) across forage types and maturity stages. The correlation between total cell wall xylose and HC concentrations (NDF-ADF) was lower than expected in all forages (R = 0.63). The more comprehensive analyses of cell walls provide detailed composition of the different WCCS that vary due to the maturity and type of cereal. © 2016 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. © 2016 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

  8. Enhanced compatibility of chemically modified titanium surface with periodontal ligament cells

    Energy Technology Data Exchange (ETDEWEB)

    Kado, T.; Hidaka, T. [Division of Periodontology and Endodontology, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293 (Japan); Aita, H. [Division of Occlusion and Removable Prosthodontics, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293 (Japan); Endo, K. [Division of Biomaterials and Bioengineering, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293 (Japan); Furuichi, Y., E-mail: furuichi@hoku-iryo-u.ac.jp [Division of Periodontology and Endodontology, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293 (Japan)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer Cell-adhesive molecules were covalently immobilized on a Ti surface. Black-Right-Pointing-Pointer Immobilized cell-adhesive molecules maintained native function on the Ti surface. Black-Right-Pointing-Pointer Immobilized collagen enhanced adhesion of periodontal ligament cells to the Ti. - Abstract: A simple chemical modification method was developed to immobilize cell-adhesive molecules on a titanium surface to improve its compatibility with human periodontal ligament cells (HPDLCs).The polished titanium disk was immersed in 1% (v/v) p-vinylbenzoic acid solution for 2 h to introduce carboxyl groups onto the surface. After rinsing with distilled deionized water, the titanium disk was dipped into 1.47% 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide solution containing 0.1 mg/ml Gly-Arg-Gly-Asp-Ser (GRGDS), human plasma fibronectin (pFN), or type I collagen from calf skin (Col) to covalently immobilize the cell-adhesive molecules on the titanium surface via formation of peptide bonds. X-ray photoelectron spectroscopy analyses revealed that cell-adhesive molecules were successfully immobilized on the titanium surfaces. The Col-immobilized titanium surface revealed higher values regarding nano rough characteristics than the as-polished titanium surface under scanning probe microscopy. The number of HPDLCs attached to both the pFN- and Col-immobilized titanium surfaces was twice that attached to the as-polished titanium surfaces. The cells were larger with the cellular processes that stretched to a greater extent on the pFN- and Col-immobilized titanium surfaces than on the as-polished titanium surface (p < 0.05). HPDLCs on the Col-immobilized titanium surfaces showed more extensive expression of vinculin at the tips of cell projections and more contiguously along the cell outline than on the as-polished, GRGDS-immobilized and pFN-immobilized titanium surfaces. It was concluded that cell-adhesive molecules successfully

  9. Participation of cytochrome P-450 in the reduction of nitro compounds by rat liver microsomes.

    Science.gov (United States)

    Harada, N; Omura, T

    1980-05-01

    1. The subcellular distribution of nitrobenzene reduction activity in rat liver cells indicated the existence of two different enzyme systems, one localized in microsomes and the other localized in cytosol. The activity in the cytosol was mainly attributable to xanthine oxidase, judging from its substrate specificity and the inhibition by allopurinol. 2. The participation of the microsomal electron transport system in nitrobenzene reduction was examined by using antibodies against four components of the system, NADPH-cytochrome c reductase (fpT), NADH-cytochrome b5 reductase (fpD), cytochrome b5, and cytochrome P-450. Both NADH- and NADPH-dependent nitrobenzene reduction activities were strongly inhibited by anti-fpT IG and also by anti-P450 IG, but not inhibited by anti-fpD IG or anti-b5 IG. The reduction of nitrosobenzene and phenylhydroxylamine, which are supposed to be the intermediates of nitrobenzene reduction, was also examined, and it was found that NADH- and NADPH-dependent reduction of both compounds were strongly inhibited by anti-fpT IG and anti-P450 IG, but not by anti-fpD IG or anti-b5 IG. 3. Reconstruction experiments using purified NADPH-cytochrome P-450 reductase and cytochrome P-450 were also carried out and it was confirmed that the reduction of nitrobenzene, nitrosobenzene, and phenylhydroxylamine to aniline could be effected by these two components. 4. Nitrobenzene reduction by microsomes exhibited a short initial time lag and was activated by the addition of purified NADPH-cytochrome c reductase, whereas nitrosobenzene and phenylhydroxylamine reductions did not show any initial time lag and were not activated by the reductase. These observations suggest that the reduction of nitrobenzene to an intermediate, possibly nitrosobenzene or phenylhydroxylamine, limits the rate of aniline formation, and such an initial step of nitrobenzene reduction can be catalyzed by NADPH-cytochrome c reductase alone. Cytochrome P-450 is essential at least in the

  10. Programmable chemical reaction networks: emulating regulatory functions in living cells using a bottom-up approach.

    Science.gov (United States)

    van Roekel, Hendrik W H; Rosier, Bas J H M; Meijer, Lenny H H; Hilbers, Peter A J; Markvoort, Albert J; Huck, Wilhelm T S; de Greef, Tom F A

    2015-11-07

    Living cells are able to produce a wide variety of biological responses when subjected to biochemical stimuli. It has become apparent that these biological responses are regulated by complex chemical reaction networks (CRNs). Unravelling the function of these circuits is a key topic of both systems biology and synthetic biology. Recent progress at the interface of chemistry and biology together with the realisation that current experimental tools are insufficient to quantitatively understand the molecular logic of pathways inside living cells has triggered renewed interest in the bottom-up development of CRNs. This builds upon earlier work of physical chemists who extensively studied inorganic CRNs and showed how a system of chemical reactions can give rise to complex spatiotemporal responses such as oscillations and pattern formation. Using purified biochemical components, in vitro synthetic biologists have started to engineer simplified model systems with the goal of mimicking biological responses of intracellular circuits. Emulation and reconstruction of system-level properties of intracellular networks using simplified circuits are able to reveal key design principles and molecular programs that underlie the biological function of interest. In this Tutorial Review, we present an accessible overview of this emerging field starting with key studies on inorganic CRNs followed by a discussion of recent work involving purified biochemical components. Finally, we review recent work showing the versatility of programmable biochemical reaction networks (BRNs) in analytical and diagnostic applications.

  11. Microbial reverse-electrodialysis chemical-production cell for acid and alkali production

    KAUST Repository

    Zhu, Xiuping

    2013-06-01

    A new type of bioelectrochemical system, called a microbial reverse-electrodialysis chemical-production cell (MRCC), was developed to produce acid and alkali using energy derived from organic matter (acetate) and salinity gradients (NaCl solutions representative of seawater and river water). A bipolar membrane (BPM) was placed next to the anode to prevent Cl- contamination and acidification of the anolyte, and to produce protons for HCl recovery. A 5-cell paired reverse-electrodialysis (RED) stack provided the electrical energy required to overcome the BPM over-potential (0.3-0.6 V), making the overall process spontaneous. The MRCC reactor produced electricity (908 mW/m2) as well as concentrated acidic and alkaline solutions, and therefore did not require an external power supply. After a fed-batch cycle, the pHs of the chemical product solutions were 1.65 ± 0.04 and 11.98 ± 0.10, due to the production of 1.35 ± 0.13 mmol of acid, and 0.59 ± 0.14 mmol of alkali. The acid- and alkali-production efficiencies based on generated current were 58 ± 3% and 25 ± 3%. These results demonstrated proof-of-concept acid and alkali production using only renewable energy sources. © 2013 Elsevier B.V.

  12. Chemoreception regulates chemical access to mouse vomeronasal organ: role of solitary chemosensory cells.

    Directory of Open Access Journals (Sweden)

    Tatsuya Ogura

    2010-07-01

    Full Text Available Controlling stimulus access to sensory organs allows animals to optimize sensory reception and prevent damage. The vomeronasal organ (VNO detects pheromones and other semiochemicals to regulate innate social and sexual behaviors. This semiochemical detection generally requires the VNO to draw in chemical fluids, such as bodily secretions, which are complex in composition and can be contaminated. Little is known about whether and how chemical constituents are monitored to regulate the fluid access to the VNO. Using transgenic mice and immunolabeling, we found that solitary chemosensory cells (SCCs reside densely at the entrance duct of the VNO. In this region, most of the intraepithelial trigeminal fibers innervate the SCCs, indicating that SCCs relay sensory information onto the trigeminal fibers. These SCCs express transient receptor potential channel M5 (TRPM5 and the phospholipase C (PLC beta2 signaling pathway. Additionally, the SCCs express choline acetyltransferase (ChAT and vesicular acetylcholine transporter (VAChT for synthesizing and packaging acetylcholine, a potential transmitter. In intracellular Ca2+ imaging, the SCCs responded to various chemical stimuli including high concentrations of odorants and bitter compounds. The responses were suppressed significantly by a PLC inhibitor, suggesting involvement of the PLC pathway. Further, we developed a quantitative dye assay to show that the amount of stimulus fluid that entered the VNOs of behaving mice is inversely correlated to the concentration of odorous and bitter substances in the fluid. Genetic knockout and pharmacological inhibition of TRPM5 resulted in larger amounts of bitter compounds entering the VNOs. Our data uncovered that chemoreception of fluid constituents regulates chemical access to the VNO and plays an important role in limiting the access of non-specific irritating and harmful substances. Our results also provide new insight into the emerging role of SCCs in

  13. Low-cost plasmonic solar cells prepared by chemical spray pyrolysis

    Directory of Open Access Journals (Sweden)

    Erki Kärber

    2014-12-01

    Full Text Available Solar cells consisting of an extremely thin In2S3/CuInS2 buffer/absorber layer uniformly covering planar ZnO were prepared entirely by chemical spray pyrolysis. Au nanoparticles (Au-NPs were formed via thermal decomposition of a gold(III chloride trihydrate (HAuCl4·3H2O precursor by spraying 2 mmol/L of the aqueous precursor solution onto a substrate held at 260 °C. Current–voltage scans and external quantum efficiency spectra were used to evaluate the solar cell performance. This work investigates the effect of the location of the Au-NP layer deposition (front side vs rear side in the solar cell and the effect of varying the volume (2.5–10 mL of the sprayed Au precursor solution. A 63% increase (from 4.6 to 7.5 mA/cm2 of the short-circuit current density was observed when 2.5 mL of the precursor solution was deposited onto the rear side of the solar cell.

  14. Mechanical and chemical studies on EPS from Sulfobacillus thermosulfidooxidans: from planktonic to biofilm cells.

    Science.gov (United States)

    Li, Qian; Sand, Wolfgang

    2017-05-01

    Bacteria attach to minerals and form biofilms, which can initiate and enhance bioleaching. Extracellular polymeric substances (EPS) play a crucial role during the whole process. Little is known how the cell surface/EPS mechanically and chemically respond to transformation from planktonic to biofilm cells. In this study the attachment and biofilm formation by Sulfobacillus thermosulfidooxidans were followed during pyrite leaching. Adhesiveness and stiffness of the cell/biofilm and the pyrite surface were checked by atomic force microscopy (AFM) in force mapping mode under real living conditions. The EPS components were analysed by colorimetry, fourier transform infrared spectroscopy and energy dispersive X-ray spectroscopy. The results indicate that slimy and soft EPS heterogeneously accumulated in the biofilms and on the surface of pyrite to induce bacterial adhesion and form robust biofilms. After attaching to the pyrite surface, the cells started to change the components of their EPS. Huge amounts of humic substances were detected in the biofilm EPS. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Chemical constituents from the fruits of Ligustrum japonicum and their inhibitory effects on T cell activation.

    Science.gov (United States)

    Ngo, Quynh-Mai Thi; Lee, Hyun-Su; Nguyen, Van Thu; Kim, Jeong Ah; Woo, Mi Hee; Min, Byung Sun

    2017-09-01

    A previously undescribed nor-dammarane, 3β,20,23-trihydroxy-24,25,26,27-tetranordammarane; three previously undescribed secoiridoid glycosides, ligujaponosides A-B, and iso-oleonuzhenide; and twenty three known compounds, were isolated from the fruits of Ligustrum japonicum Thunb. Their chemical structures were elucidated by extensive spectroscopic analyses, including 1D and 2D NMR, and HRMS. The isolated compounds were screened for immunosuppressive effects on T activated cells by evaluating interleukin-2 (IL-2) production. Among them, sesamin inhibited IL-2 production in Jurkat T cells with an IC50 value of 38 ± 2 μM. In addition, sesamin inhibited the phosphorylation of extracellular signal-regulated protein kinase (ERK), a member of the mitogen-activated protein kinase (MAPK) family, in phorbol 12-myristate 13-acetate (PMA)/A23187-stimulated T cells. Therefore, sesamin was demonstrated to inhibit T cell activation via regulation of MAPK phosphorylation pathway. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Reversible solid oxide fuel cells (R-SOFCs) with chemically stable proton-conducting oxides

    KAUST Repository

    Bi, Lei

    2015-07-01

    Proton-conducting oxides offer a promising way of lowering the working temperature of solid oxide cells to the intermediate temperate range (500 to 700. °C) due to their better ionic conductivity. In addition, the application of proton-conducting oxides in both solid oxide fuel cells (SOFCs) and sold oxide electrolysis cells (SOECs) provides unique advantages compared with the use of conventional oxygen-ion conducting conductors, including the formation of water at the air electrode site. Since the discovery of proton conduction in some oxides about 30. years ago, the development of proton-conducting oxides in SOFCs and SOECs (the reverse mode of SOFCs) has gained increased attention. This paper briefly summarizes the development in the recent years of R-SOFCs with proton-conducting electrolytes, focusing on discussing the importance of adopting chemically stable materials in both fuel cell and electrolysis modes. The development of electrode materials for proton-conducting R-SOFCs is also discussed. © 2015 Elsevier B.V.

  17. miRNA regulatory circuits in ES cells differentiation: a chemical kinetics modeling approach.

    Directory of Open Access Journals (Sweden)

    Zijun Luo

    Full Text Available MicroRNAs (miRNAs play an important role in gene regulation for Embryonic Stem cells (ES cells, where they either down-regulate target mRNA genes by degradation or repress protein expression of these mRNA genes by inhibiting translation. Well known tables TargetScan and miRanda may predict quite long lists of potential miRNAs inhibitors for each mRNA gene, and one of our goals was to strongly narrow down the list of mRNA targets potentially repressed by a known large list of 400 miRNAs. Our paper focuses on algorithmic analysis of ES cells microarray data to reliably detect repressive interactions between miRNAs and mRNAs. We model, by chemical kinetics equations, the interaction architectures implementing the two basic silencing processes of miRNAs, namely "direct degradation" or "translation inhibition" of targeted mRNAs. For each pair (M,G of potentially interacting miRMA gene M and mRNA gene G, we parameterize our associated kinetic equations by optimizing their fit with microarray data. When this fit is high enough, we validate the pair (M,G as a highly probable repressive interaction. This approach leads to the computation of a highly selective and drastically reduced list of repressive pairs (M,G involved in ES cells differentiation.

  18. Adjustment of surface chemical and physical properties with functionalized polymers to control cell adhesion

    Science.gov (United States)

    Zhou, Zhaoli

    Cell-surface interaction is crucial in many cellular functions such as movement, growth, differentiation, proliferation and survival. In the present work, we have developed several strategies to design and prepare synthetic polymeric materials with selected cues to control cell attachment. To promote neuronal cell adhesion on the surfaces, biocompatible, non-adhesive PEG-based materials were modified with neurotransmitter acetylcholine functionalities to produce hydrogels with a range of porous structures, swollen states, and mechanical strengths. Mice hippocampal cells cultured on the hydrogels showed differences in number, length of processes and exhibited different survival rates, thereby highlighting the importance of chemical composition and structure in biomaterials. Similar strategies were used to prepare polymer brushes to assess how topographical cues influence neuronal cell behaviors. The brushes were prepared using the "grown from" method through surface-initiated atom transfer radical polymerization (SI-ATRP) reactions and further patterned via UV photolithography. Protein absorption tests and hippocampal neuronal cell culture of the brush patterns showed that both protein and neuronal cells can adhere to the patterns and therefore can be guided by the patterns at certain length scales. We also prepared functional polymers to discourage attachment of undesirable cells on the surfaces. For example, we synthesized PEG-perfluorinated alkyl amphiphilic surfactants to modify polystyrene-block-poly(ethylene-ran-butylene)- block-polyisoprene (SEBI or K3) triblock copolymers for marine antifouling/fouling release surface coatings. Initial results showed that the polymer coated surfaces can facilitate removal of Ulva sporelings on the surfaces. In addition, we prepared both bioactive and dual functional biopassive/bioactive antimicrobial coatings based on SEBI polymers. Incubating the polymer coated surfaces with gram-positive bacteria (S. aureus), gram

  19. Alteration of pituitary hormone-immunoreactive cell populations in rat offspring after maternal dietary exposure to endocrine-active chemicals.

    Science.gov (United States)

    Masutomi, Naoya; Shibutani, Makoto; Takagi, Hironori; Uneyama, Chikako; Lee, Kyoung-Youl; Hirose, Masao

    2004-04-01

    We previously performed dose-response studies of genistein, diisononyl phthalate, 4-nonylphenol, methoxychlor (MXC), and bisphenol A to examine the impact of maternal dietary exposure from gestational day 15 to postnatal day 10 on the development of rat reproductive system in later life. Among the chemicals MXC alone showed typical estrogenic effects only at the maternally toxic 1200 ppm. The present study was performed to examine the sensitivity of immunohistochemical analysis of pituitary cells of offspring similarly exposed to each chemical for detection of endocrine-disrupting effects. For this purpose, ratios of pituitary cells expressing luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin (PRL), were measured at 3 and 11 weeks of age. Ethinylestradiol (EE) at 0.5 ppm was used as a reference chemical. At week 3, decrease in the relative proportions of LH, FSH, and PRL cells in males and LH cells in females was evident with MXC at 1200 ppm. At week 11, increase was found for PRL cells from 240 ppm MXC, and FSH cells at 1200 ppm in females. On the other hand, EE increased the PRL cell percentage in females at week 3 but no effects were apparent at week 11. The other chemicals were without influence at either time point. The results suggest that the assessment of the pituitary cell populations might be a more sensitive approach to detect perinatal endocrine-disrupting effects than other methods. The difference in the pituitary effect between MXC and EE is discussed.

  20. Effects of the EVCAM chemical validation library on differentiation using marker gene expression in lmouse embryonic stem cells

    Science.gov (United States)

    The adherent cell differentiation and cytotoxicity (ACDC) assay was used to profile the effects of the ECVAM EST validation chemical library (19 compounds) on J1 mouse embryonic stem cells (mESC). PCR-based TaqMan Low Density Arrays (TLDA) provided a high-content assessment of al...

  1. Chemical form of selenium affects its uptake, transport and glutathione peroxidase activity in the human intestinal Caco-2 cell model

    Science.gov (United States)

    Determining the effect of selenium (Se) chemical form on uptake and transport in human intestinal cells is critical to assess Se bioavailability. In the present study, we measured the uptake and transport of various Se compounds in the human intestinal Caco-2 cell model. We found that two sources...

  2. (+)-Abscisic acid 8'-hydroxylase is a cytochrome P450 monooxygenase

    Science.gov (United States)

    Krochko; Abrams; Loewen; Abrams; Cutler

    1998-11-01

    Abscisic acid (ABA) 8'-hydroxylase catalyzes the first step in the oxidative degradation of (+)-ABA. The development of a robust in vitro assay has now permitted detailed examination and characterization of this enzyme. Although several factors (buffer, cofactor, and source tissue) were critical in developing the assay, the most important of these was the identification of a tissue displaying high amounts of in vivo enzyme activity (A.J. Cutler, T.M. Squires, M.K. Loewen, J.J. Balsevich [1997] J Exp Bot 48: 1787-1795). (+)-ABA 8'-hydroxylase is an integral membrane protein that is localized to the microsomal fraction in suspension-cultured maize (Zea mays) cells. (+)-ABA metabolism requires both NADPH and molecular oxygen. NADH was not an effective cofactor, although there was substantial stimulation of activity (synergism) when it was included at rate-limiting NADPH concentrations. The metabolism of (+)-ABA was progressively inhibited at O2 concentrations less than 10% (v/v) and was very low (less than 5% of control) under N2. (+)-ABA 8'-hydroxylase activity was inhibited by tetcyclacis (50% inhibition at 10(-6) M), cytochrome c (oxidized form), and CO. The CO inhibition was reversible by light from several regions of the visible spectrum, but most efficiently by blue and amber light. These data strongly support the contention that (+)-ABA 8'-hydroxylase is a cytochrome P450 monooxygenase.

  3. Oxidation of c-Type Cytochromes by the Membrane-Bound Cytochrome Oxidase (Cytochrome aa(3)) of Blue-Green Algae.

    Science.gov (United States)

    Kienzl, P F; Peschek, G A

    1982-03-01

    Respiratory particles containing an aa(3)-type cytochrome oxidase were prepared from Anacystis nidulans, Synechocystis 6714, Synechococcus lividus, Anabaena variabilis, Nostoc sp. strain MAC, Nostoc muscorum, and Mastigocladus laminosus. Oxidation of c-type cytochromes by membrane preparations of the different blue-green algae was observed using purified cytochromes from horse heart, Candida krusei, tuna, Saccharomyces oviformis, Rhodospirillum rubrum, Rhodospirillum molischianum, Rhodopseudomonas palustris, Rhodocyclus purpureus, Paracoccus denitrificans, Anacystis nidulans, Anabaena variabilis, Euglena gracilis, and Scenedesmus obliquus. Rapid oxidations were consistently observed with the mitochondrial c-type cytochromes (horse heart cytochrome c reacts most rapidly) and with cytochromes c(2) from Rhodopseudomonas palustris and Rhodocyclus purpureus; in contrast, the cytochrome c(2) from Rhodospirillum rubrum and the plastidic cytochromes from E. gracilis and Scendesmus obliquus were inactive with all membrane preparations. All reactions were inhibited by low concentrations of KCN, NaN(3), and CO, and they were activated by Tween 80, thus indicating participation of the terminal oxidase. The results are discussed in view of the spectral similarities between the terminal oxidase of blue-green algae and the mitochondrial aa(3)-type cytochrome oxidase of plants and other eukaryotes.

  4. Evaluation of Inhibition Selectivity for Human Cytochrome P450 2A Enzymes

    OpenAIRE

    Stephens, Eva S.; Walsh, Agnes A.; Scott, Emily E.

    2012-01-01

    Cytochrome P450 (P450) enzymes are mixed-function oxidases that catalyze the metabolism of xenobiotics and endogenous biochemicals. Selective inhibitors are needed to accurately distinguish the contributions of individual P450 enzymes in the metabolism of drugs and the activation of procarcinogens in human tissues, but very frequently these enzymes have substantial overlapping selectivity. We evaluated a chemically diverse set of nine previously identified CYP2A6 inhibitors to determine which...

  5. [Inhibition of cytochrome b2 by acrylamide].

    Science.gov (United States)

    Kulis, Iu Iu; Shvirmitskas, G Iu; Antanavichius, V S; Vaitkiavichius, R K

    1982-04-01

    Acrylamide (0.4--0.9 M) irreversibly inhibits reduced (Ered) cytochrome b2 (L (+) -lactate: cytochrome c oxidoreductase) from the yeast Hansenula anomala (ki = 1,67 min-1 at 35 degrees in 0.73 M solution of acrylamide). Changes in fluorescence of FMN, which reflect the changes in protein structure occur symbatically to the inactivation. The rate of inactivation depends on concentration of acrylamide in a degree of 6.4. The inactivation of the oxidized enzyme occurs faster than that of th reduced one at concentrations less than 0.5 M. The inactivation of Ered by acrylonitrile and acrylic acid occurs 10 times slower and does not correlate with the rate of mercaptoethanol binding to the monomers. The inhibition of Ered is caused by specific effects of carylamide and modification of the enzyme active center.

  6. Scalable cultivation of human pluripotent stem cells on chemically-defined surfaces

    Science.gov (United States)

    Hsiung, Michael Chi-Wei

    Human stem cells (SCs) are classified as self-renewing cells possessing great ability in therapeutic applications due of their ability to differentiate along any major cell lineage in the human body. Despite their restorative potential, widespread use of SCs is hampered by strenuous control issues. Along with the need for strict xeno-free environments to sustain growth in culture, current methods for growing human pluripotent stem cells (hPSCs) rely on platforms which impede large-scale cultivation and therapeutic delivery. Hence, any progress towards development of large-scale culture systems is severely hindered. In a concentrated effort to develop a scheme that can serve as a model precursor for large scale SC propagation in clinical use, we have explored methods for cultivating hPSCs on completely defined surfaces. We discuss novel approaches with the potential to go beyond the limitations presented by current methods. In particular, we studied the cultivation of human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) on surface which underwent synthetic or chemical modification. Current methods for hPSCs rely on animal-based extracellular matrices (ECMs) such as mouse embryonic fibroblasts (MEFs) or feeders and murine sacoma cell-derived substrates to facilitate their growth. While these layers or coatings can be used to maximize the output of hPSC production, they cannot be considered for clinical use because they risk introducing foreign pathogens into culture. We have identified and developed conditions for a completely defined xeno-free substrate used for culturing hPSCs. By utilizing coupling chemistry, we can functionalize ester groups on a given surface and conjugate synthetic peptides containing the arginine-glycine-aspartic acid (RGD) motif, known for their role in cell adhesion. This method offers advantages over traditional hPSC culture by keeping the modified substrata free of xenogenic response and can be scaled up in

  7. Targeting Slit-Roundabout signaling inhibits tumor angiogenesis in chemical-induced squamous cell carcinogenesis.

    Science.gov (United States)

    Wang, Li-Jing; Zhao, Yuan; Han, Bing; Ma, Yu-Guang; Zhang, Jie; Yang, Ding-Ming; Mao, Jian-Wen; Tang, Fu-Tian; Li, Wei-Dong; Yang, Yang; Wang, Rui; Geng, Jian-Guo

    2008-03-01

    Slit is a secreted protein known to function through the Roundabout (Robo) receptor as a repellent for axon guidance and neuronal migration, and as an inhibitor in leukocyte chemotaxis. We have previously shown that Slit2 is also secreted by a variety of human cancer cells whereby it acts as a chemoattractant to vascular endothelial cells for tumor angiogenesis. We used a blocking antibody to investigate the role of Slit-Robo signaling in tumor angiogenesis during oral carcinogenesis. In this report we undertook a multistage model of 7,12-dimethyl-1,2-benzanthracene-induced squamous cell carcinoma in the hamster buccal pouch. R5, a monoclonal antibody against the first immunoglobulin domain of Robo1, was used to study whether R5 blocks the Slit-Robo interaction and furthermore inhibits tumor angiogenesis and growth in our model. In addition, the expression of Slit2, von Willebrand factor, and vascular endothelial growth factor were examined using human tissue of oral cheek mucosa with oral squamous cell carcinoma. Our data showed that Slit2 was expressed minimally in normal and hyperplastic mucosa, moderately in dysplastic mucosa, and highly in neoplastic mucosa obtained from hamster buccal pouch. We also found that increased Slit2 expression was associated with higher tumor angiogenesis, as reflected by increased vascular endothelial growth factor expression and microvessel density. A similar Slit2 expression profile was found in human tissue. Importantly, interruption of the Slit2-Robo interaction using R5 inhibited tumor angiogenesis and growth in our in vivo model, which indicates that Slit2-mediated tumor angiogenesis is a critical process underlying the carcinogenesis of chemical-induced squamous cell carcinoma. Therefore, targeting Slit-Robo signaling may offer a novel antiangiogenesis approach for oral cancer therapy.

  8. Chemical vapour etching-based porous silicon and grooving: Application in silicon solar cells processing

    Energy Technology Data Exchange (ETDEWEB)

    Ben Rabha, M.; Boujmil, M.F.; Saadoun, M.; Bessais, B. [Institut National de Recherche Scientifique et Technique, Laboratoire de Photovoltaique et des Semiconducteurs, BP 95, 2050 Hammam-Lif (Tunisia)

    2005-06-01

    Sponge like porous silicon (PS) was formed by a simple and low cost chemical vapour etching (CVE) method and applied in polycrystalline silicon (mc-Si) solar cells processing. The CVE method consists of exposing Si wafers to HNO{sub 3}/HF vapours. It was shown that 8 min of HNO{sub 3}/HF CVE (volume ratio = 1/7) is sufficient to form optimized PS layers on the emitter of mc-Si cells. The CVE-based PS can simultaneously passivate the Si surface and serves as an effective antireflection coating (ARC). As a result, the reflectivity decreases by about 60% of its initial value and the internal quantum efficiency is improved, particularly in the short wavelength region. For acid vapours rich in HNO{sub 3} (HNO{sub 3}/HF >1/4), the CVE method favours the formation of a (NH{sub 4}){sub 2}SiF{sub 6} powder, which is highly soluble in water. These findings let us achieve anisotropic grooving that enables to groove mc-Si wafers locally and in depth using an adequate anti-acid mask. The CVE - based grooving technique was used to form buried metallic contacts on the rear and frontal surface of the Si wafer in order to improve the current collection in mc-Si solar cells. No alteration of the spectral response in the long wavelength range was observed in mc-Si cells with rear-buried contacts. Adjustments of theoretical spectral responses to experimental ones show an increase in the effective electron diffusion length (Ln), which was attributed to Al gettering (passivation) at grain boundaries and to the reduction of the effective thickness of the base of the cells. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Effect of butylated hydroxytoluene, curcumin, propyl gallate and thiabendazole on cytochrome P450 forms in cultured human hepatocytes

    NARCIS (Netherlands)

    Price, R.J.; Scott, M.P.; Giddings, A.M.; Walters, D.G.; Stierum, R.H.; Meredith, C.; Lake, B.G.

    2008-01-01

    1. The objective of this study was to investigate the effects of four food chemicals, namely butylated hydroxytoluene (BHT), curcumin (CC), propyl gallate (PG) and thiabendazole (TB), on cytochrome P450 (CYP) forms in cultured human hepatocytes. 2. Treatment of human hepatocytes for 72 h with 2-200

  10. De-bugging and maximizing plant cytochrome P450 production in Escherichia coli with C-terminal GFP fusions

    DEFF Research Database (Denmark)

    Christensen, Ulla; Vazquez Albacete, Dario; Søgaard, Karina Marie

    2017-01-01

    Cytochromes P450 (CYP) are attractive enzyme targets in biotechnology as they catalyze stereospecific C-hydroxylations of complex core skeletons at positions that typically are difficult to access by chemical synthesis. Membrane bound CYPs are involved in nearly all plant pathways leading...

  11. Evaluation of alkoxyresorufins as fluorescent substrates for cytochrome P450 BM3 and site-directed mutants

    NARCIS (Netherlands)

    Lussenburg, B.M.A.; Babel, L.C.; Vermeulen, N.P.E.; Commandeur, J.N.M.

    2005-01-01

    In this study, the first fluorescent assay for bacterial cytochrome P450 BM3 (BM3) and mutants is described. BM3 mutants are potentially very versatile biocatalysts for the production of fine chemicals. A fluorescent assay would be very useful for the identification of nonnatural ligands in

  12. Early evolution of cytochrome bc complexes.

    Science.gov (United States)

    Schütz, M; Brugna, M; Lebrun, E; Baymann, F; Huber, R; Stetter, K O; Hauska, G; Toci, R; Lemesle-Meunier, D; Tron, P; Schmidt, C; Nitschke, W

    2000-07-21

    Primary structures, functional characteristics and phylogenetic relationships of subunits of cytochrome bc complexes from phylogenetically diverse bacterial and archaeal species were analysed. A single case of lateral gene transfer, i.e. the import of an epsilon-proteobacterial cytochrome bc(1) complex into Aquificales, was identified. For the enzyme in the remainder of the species studied, the obtained phylogenies were globally in line with small subunit rRNA trees. The distribution of a few key phylogenetic markers, such as contiguousness of cytochrome b, nature of the c-type subunit or spacing between b-heme ligands, are discussed. A localised modification of previous tree topologies is proposed on the basis of the obtained data. The comparison of extant enzymes furthermore allowed us to define the minimal functional and evolutionary core of the enzyme. The data furthermore suggest that the ancestral enzyme was put together from subunits that previously had played a role in other electron transfer chains. Copyright 2000 Academic Press.

  13. Vesicle-based artificial cells as chemical microreactors with spatially segregated reaction pathways

    Science.gov (United States)

    Elani, Yuval; Law, Robert V.; Ces, Oscar

    2014-10-01

    In the discipline of bottom-up synthetic biology, vesicles define the boundaries of artificial cells and are increasingly being used as biochemical microreactors operating in physiological environments. As the field matures, there is a need to compartmentalize processes in different spatial localities within vesicles, and for these processes to interact with one another. Here we address this by designing and constructing multi-compartment vesicles within which an engineered multi-step enzymatic pathway is carried out. The individual steps are isolated in distinct compartments, and their products traverse into adjacent compartments with the aid of transmembrane protein pores, initiating subsequent steps. Thus, an engineered signalling cascade is recreated in an artificial cellular system. Importantly, by allowing different steps of a chemical pathway to be separated in space, this platform bridges the gap between table-top chemistry and chemistry that is performed within vesicles.

  14. Characterization of chemical bath deposited buffer layers for thin film solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Dwyer, D.; Efstathiadis, H.; Haldar, P. [College of Nanoscale Science and Engineering, University at Albany - State University of New York, 257 Fuller Rd., Albany, NY 12203 (United States); Sun, R. [Angstrom Sun Technologies Inc., 33 Nagog Park, Acton, MA 01720 (United States)

    2010-10-15

    Cadmium sulfide (CdS), indium sulfide (In{sub 2}S{sub 3}) and zinc sulfide (ZnS) thin films have been deposited by chemical bath deposition (CBD) for buffer layer applications in Cu-chalcopyrite-based thin film solar cells. Films were characterized by scanning electron microscopy (SEM), UV-Vis transmission, X-ray photoelectron spectroscopy (XPS), grazing-incidence X-ray diffraction (GIXRD), and spectroscopic ellipsometry. Results indicate CdS can be deposited with low oxygen content and high light transmission over 245-1700 nm. CBD-ZnS and CBD-InS both exhibit 5-10% less light transmission than CdS in the same thickness range. In terms of light transmission and degree of impurities CdS appears to be a better buffer material than CBD-ZnS or CBD-InS. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  15. Zinc Sulfide Buffer Layer for CIGS Solar Cells Prepared by Chemical Bath Deposition

    Directory of Open Access Journals (Sweden)

    Rui-Wei You

    2016-11-01

    Full Text Available In this study, ZnS thin films were successfully synthesized by chemical bath deposition (CBD with starting materials of NH2-NH2, SC(NH22, and ZnSO4‧7H2O. ZnS thin films were deposited with different time on glass substrates by CBD at 80oC and pH=9. Based on X-ray diffraction (XRD patterns, it is found that the ZnS thin films exhibit cubic polycrystalline phase. It was found that the optimum deposition time is 90 min for preparing ZnS thin film that is suitable as buffer layer for CuIn1-xGaxSe2 solar cells. The thin film deposited for 90 min has high transmittance up to 80% in the spectra range from 350 nm to 800 nm, and the optical band gap is about 3.59 eV.

  16. Further studies on the detection of chemical agents using an alkaline energy cell

    Science.gov (United States)

    Shewchun, John

    2008-04-01

    The detection, classification and tracking of chemical agents (explosives) being surreptitiously smuggled into public areas, such as airports, for destructive purposes is difficult to solve by unobtrusive means. We propose the use of a novel Alkaline Energy Cell (AEC) with gas/vapor sniffing capability as a potential solution. Variants of such devices are routinely used by police to detect alcohol emanating from the breath of suspected impaired vehicle drivers. We reported previously at the SPIE Symposium in 2007 the details of our technology and results. We have continued to advanced this capability with the development of an AEC which is capable of detecting gaseous emissions ultimately in the parts per billion range. Our work is described in terms of detecting TATP (acetone peroxide). Other explosive materials have also been investigated and will be reported on.

  17. Defense Waste Processing Facility Nitric- Glycolic Flowsheet Chemical Process Cell Chemistry: Part 2

    Energy Technology Data Exchange (ETDEWEB)

    Zamecnik, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Edwards, T. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-06-06

    The conversions of nitrite to nitrate, the destruction of glycolate, and the conversion of glycolate to formate and oxalate were modeled for the Nitric-Glycolic flowsheet using data from Chemical Process Cell (CPC) simulant runs conducted by Savannah River National Laboratory (SRNL) from 2011 to 2016. The goal of this work was to develop empirical correlation models to predict these values from measureable variables from the chemical process so that these quantities could be predicted a-priori from the sludge or simulant composition and measurable processing variables. The need for these predictions arises from the need to predict the REDuction/OXidation (REDOX) state of the glass from the Defense Waste Processing Facility (DWPF) melter. This report summarizes the work on these correlations based on the aforementioned data. Previous work on these correlations was documented in a technical report covering data from 2011-2015. This current report supersedes this previous report. Further refinement of the models as additional data are collected is recommended.

  18. Expanding the chemical palate of cells by combining systems biology and metabolic engineering.

    Science.gov (United States)

    Curran, Kathleen A; Alper, Hal S

    2012-07-01

    The field of Metabolic Engineering has recently undergone a transformation that has led to a rapid expansion of the chemical palate of cells. Now, it is conceivable to produce nearly any organic molecule of interest using a cellular host. Significant advances have been made in the production of biofuels, biopolymers and precursors, pharmaceuticals and nutraceuticals, and commodity and specialty chemicals. Much of this rapid expansion in the field has been, in part, due to synergies and advances in the area of systems biology. Specifically, the availability of functional genomics, metabolomics and transcriptomics data has resulted in the potential to produce a wealth of new products, both natural and non-natural, in cellular factories. The sheer amount and diversity of this data however, means that uncovering and unlocking novel chemistries and insights is a non-obvious exercise. To address this issue, a number of computational tools and experimental approaches have been developed to help expedite the design process to create new cellular factories. This review will highlight many of the systems biology enabling technologies that have reduced the design cycle for engineered hosts, highlight major advances in the expanded diversity of products that can be synthesized, and conclude with future prospects in the field of metabolic engineering. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Room-temperature chemical integration of ZnO nanoarchitectures on plastic substrates for flexible dye-sensitized solar cells.

    Science.gov (United States)

    Chang, Geng-Jia; Lin, Shou-Yen; Wu, Jih-Jen

    2014-01-01

    ZnO nanoarchitectured anodes composed of the ZnO nanocactus array and the top ZnO particle layer are chemically integrated on ITO-PET substrates using a facile room-temperature chemical bath deposition method for dye-sensitized solar cells (DSSCs). In the absence of high-temperature post-treatment and mechanical compression, a notable efficiency of 5.24% is simply achieved in the flexible ZnO DSSC.

  20. Cytochrome P450-mediated metabolism of tumour promoters modifies the inhibition of intercellular communication: a modified assay for tumour promotion

    DEFF Research Database (Denmark)

    Vang, Ole; Wallin, H.; Doehmer, J.

    1993-01-01

    The role of metabolism of tumour promoters on the inhibition of intercellular communication was investigated in a modified V79 metabolic cooperation system. V79 cells, which stably express different rat cytochrome P450 enzymes (CYP1A1, CYP1A2 or CYP2B1), were used in the metabolic cooperation assay...... B1 and 4-nitrobiphenyl, did not inhibit metabolic cooperation in either V79 cells expressing or cells not expressing cytochrome P450. We conclude that cytochrome P450-associated metabolism plays an important role in the inhibition of gap junctional intercellular communication of some tumour......-associated metabolism. 7-Octylindolactam V was as potent as TPA, whereas the related indolactam V was 100-fold less active. The carcinogenic aromatic amine 4-aminobiphenyl, but not its primary metabolite 4-hydroxyaminobiphenyl, inhibited metabolic cooperation. Other known carcinogens, ochratoxin A, aflatoxin...

  1. Steroid profiling in H295R cells to identify chemicals potentially disrupting the production of adrenal steroids.

    Science.gov (United States)

    Strajhar, Petra; Tonoli, David; Jeanneret, Fabienne; Imhof, Raphaella M; Malagnino, Vanessa; Patt, Melanie; Kratschmar, Denise V; Boccard, Julien; Rudaz, Serge; Odermatt, Alex

    2017-04-15

    The validated OECD test guideline 456 based on human adrenal H295R cells promotes measurement of testosterone and estradiol production as read-out to identify potential endocrine disrupting chemicals. This study aimed to establish optimal conditions for using H295R cells to detect chemicals interfering with the production of key adrenal steroids. H295R cells' supernatants were characterized by liquid chromatography-mass spectrometry (LC-MS)-based steroid profiling, and the influence of experimental conditions including time and serum content was assessed. Steroid profiles were determined before and after incubation with reference compounds and chemicals to be tested for potential disruption of adrenal steroidogenesis. The H295R cells cultivated according to the OECD test guideline produced progestins, glucocorticoids, mineralocorticoids and adrenal androgens but only very low amounts of testosterone. However, testosterone contained in Nu-serum was metabolized during the 48h incubation. Thus, inclusion of positive and negative controls and a steroid profile of the complete medium prior to the experiment (t=0h) was necessary to characterize H295R cells' steroid production and indicate alterations caused by exposure to chemicals. Among the tested chemicals, octyl methoxycinnamate and acetyl tributylcitrate resembled the corticosteroid induction pattern of the positive control torcetrapib. Gene expression analysis revealed that octyl methoxycinnamate and acetyl tributylcitrate enhanced CYP11B2 expression, although less pronounced than torcetrapib. Further experiments need to assess the toxicological relevance of octyl methoxycinnamate- and acetyl tributylcitrate-induced corticosteroid production. In conclusion, the extended profiling and appropriate controls allow detecting chemicals that act on steroidogenesis and provide initial mechanistic evidence for prioritizing chemicals for further investigations. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Chemical Induction of Endogenous Retrovirus Particles from the Vero Cell Line of African Green Monkeys▿

    Science.gov (United States)

    Ma, Hailun; Ma, Yunkun; Ma, Wenbin; Williams, Dhanya K.; Galvin, Teresa A.; Khan, Arifa S.

    2011-01-01

    Endogenous retroviral sequences are present in high copy numbers in the genomes of all species and may be expressed as RNAs; however, the majority are defective for virus production. Although virus has been isolated from various Old World monkey and New World monkey species, there has been no report of endogenous retroviruses produced from African green monkey (AGM) tissues or cell lines. We have recently developed a stepwise approach for evaluating the presence of latent viruses by chemical induction (Khan et al., Biologicals 37:196–201, 2009). Based upon this strategy, optimum conditions were determined for investigating the presence of inducible, endogenous retroviruses in the AGM-derived Vero cell line. Low-level reverse transcriptase activity was produced with 5-azacytidine (AzaC) and with 5′-iodo-2′-deoxyuridine (IUdR); none was detected with sodium butyrate. Nucleotide sequence analysis of PCR-amplified fragments from the gag, pol, and env regions of RNAs, prepared from ultracentrifuged pellets of filtered supernatants, indicated that endogenous retrovirus particles related to simian endogenous type D betaretrovirus (SERV) sequences and baboon endogenous virus type C gammaretrovirus (BaEV) sequences were induced by AzaC, whereas SERV sequences were also induced by IUdR. Additionally, sequence heterogeneity was seen in the RNAs of SERV- and BaEV-related particles. Infectivity analysis of drug-treated AGM Vero cells showed no virus replication in cell lines known to be susceptible to type D simian retroviruses (SRVs) and to BaEV. The results indicated that multiple, inducible endogenous retrovirus loci are present in the AGM genome that can encode noninfectious, viruslike particles. PMID:21543506

  3. Chemically Defined and Xeno-Free Cryopreservation of Human Adipose-Derived Stem Cells

    Science.gov (United States)

    López, Melany; Bollag, Roni J.; Yu, Jack C.; Isales, Carlos M.; Eroglu, Ali

    2016-01-01

    The stromal compartment of adipose tissue harbors multipotent cells known as adipose-derived stem cells (ASCs). These cells can differentiate into various lineages including osteogenic, chrondrogenic, adipogenic, and neurogenic; this cellular fraction may be easily obtained in large quantities through a clinically safe liposuction procedure. Therefore, ASCs offer exceptional opportunities for tissue engineering and regenerative medicine. However, current practices involving ASCs typically use fetal bovine serum (FBS)-based cryopreservation solutions that are associated with risks of immunological reactions and of transmitting infectious diseases and prions. To realize clinical applications of ASCs, serum- and xeno-free defined cryopreservation methods are needed. To this end, an animal product-free chemically defined cryopreservation medium was formulated by adding two antioxidants (reduced glutathione and ascorbic acid 2-phosphate), two polymers (PVA and ficoll), two permeating cryoprotectants (ethylene glycol and dimethylsulfoxide), a disaccharide (trehalose), and a calcium chelator (EGTA) to HEPES-buffered DMEM/F12. To limit the number of experimental groups, the concentration of trehalose, both polymers, and EGTA was fixed while the presence of the permeating CPAs and antioxidants was varied. ASCs suspended either in different versions of the defined medium or in the conventional undefined cryopreservation medium (10% dimethylsulfoxide+10% DMEM/F12+80% serum) were cooled to -70°C at 1°C/min before being plunged into liquid nitrogen. Samples were thawed either in air or in a water bath at 37°C. The presence of antioxidants along with 3.5% concentration of each penetrating cryoprotectant improved the freezing outcome to the level of the undefined cryopreservation medium, but the plating efficiency was still lower than that of unfrozen controls. Subsequently, increasing the concentration of both permeating cryoprotectants to 5% further improved the plating

  4. Osteoblast adhesion, migration, and proliferation variations on chemically patterned nanocrystalline diamond films evaluated by live-cell imaging.

    Science.gov (United States)

    Broz, Antonin; Ukraintsev, Egor; Kromka, Alexander; Rezek, Bohuslav; Hubalek Kalbacova, Marie

    2017-05-01

    Cell fate modulation by adapting the surface of a biocompatible material is nowadays a challenge in implantology, tissue engineering as well as in construction of biosensors. Nanocrystalline diamond (NCD) thin films are considered promising in these fields due to their extraordinary physical and chemical properties and diverse ways in which they can be modified structurally and chemically. The initial cell distribution, the rate of cell adhesion, distance of cell migration and also the cell proliferation are influenced by the NCD surface termination. Here, we use real-time live-cell imaging to investigate the above-mentioned processes on oxidized NCD (NCD-O) and hydrogenated NCD (NCD-H) to elucidate cell preference to the NCD-O especially on surfaces with microscopic surface termination patterns. Cells adhere more slowly and migrate farther on NCD-H than on NCD-O. Cells seeded with a fetal bovine serum (FBS) supplement in the medium move across the surface prior to adhesion. In the absence of FBS, the cells adhere immediately, but still exhibit different migration and proliferation on NCD-O/H regions. We discuss the impact of these effects on the formation of cell arrays on micropatterned NCD. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1469-1478, 2017. © 2017 Wiley Periodicals, Inc.

  5. Chemically controllable fabrication of one-dimensional ZnO nanostructures and their applications in solar cells.

    Science.gov (United States)

    Zhang, Yuqi; Heng, Liping; Jiang, Lei

    2014-08-01

    One-dimensional (1D) ZnO nanostructures have attracted much attention due to their interesting optical and electronic properties, which make them suitable for a wide variety of current and future technological applications, including photodetectors, photovoltaics, photocatalysis, field emissions, gas sensors and solar cells. This review gives a comprehensive overview of recent developments in chemically controllable fabrication of 1D ZnO nanomaterials. We will cover the synthetic techniques including chemical vapor deposition (CVD), metal-organic chemical vapor deposition (MOCVD), hydrothermal technique, solvothermal synthesis, sol-gel method, electrochemical deposition, and nanosphere lithography technique. Finally, we will also highlight their application in the energy conversion system.

  6. The Oxford-Diamond In Situ Cell for studying chemical reactions using time-resolved X-ray diffraction.

    Science.gov (United States)

    Moorhouse, Saul J; Vranješ, Nenad; Jupe, Andrew; Drakopoulos, Michael; O'Hare, Dermot

    2012-08-01

    A versatile, infrared-heated, chemical reaction cell has been assembled and commissioned for the in situ study of a range of chemical syntheses using time-resolved energy-dispersive X-ray diffraction (EDXRD) on Beamline I12 at the Diamond Light Source. Specialized reactor configurations have been constructed to enable in situ EDXRD investigation of samples under non-ambient conditions. Chemical reactions can be studied using a range of sample vessels such as alumina crucibles, steel hydrothermal autoclaves, and glassy carbon tubes, at temperatures up to 1200 °C.

  7. The Oxford-Diamond In Situ Cell for studying chemical reactions using time-resolved X-ray diffraction

    Science.gov (United States)

    Moorhouse, Saul J.; Vranješ, Nenad; Jupe, Andrew; Drakopoulos, Michael; O'Hare, Dermot

    2012-08-01

    A versatile, infrared-heated, chemical reaction cell has been assembled and commissioned for the in situ study of a range of chemical syntheses using time-resolved energy-dispersive X-ray diffraction (EDXRD) on Beamline I12 at the Diamond Light Source. Specialized reactor configurations have been constructed to enable in situ EDXRD investigation of samples under non-ambient conditions. Chemical reactions can be studied using a range of sample vessels such as alumina crucibles, steel hydrothermal autoclaves, and glassy carbon tubes, at temperatures up to 1200 °C.

  8. The electron transport system of the anaerobic Propionibacterium shermanii: cytochrome and inhibitor studies.

    Science.gov (United States)

    Schwartz, A C; Sporkenbach, J

    1975-03-10

    1. Electron transport particles obtained from cell-free extracts of Propionibacterium shermanii by centrifugation at 105000 times g for 3 hrs oxidized NADH, D,L-lactate, L-glycerol-3-phosphate and succinate with oxygen and, except for succinate, with fumarate, too. 2. Spectral investigation of the electron transport particles revealed the presence of cytochromes b, d and o, and traces of cytochrome alpha1 and a c-type cytochrome. Cytochrome b was reduced by succinate to about 50%, and by NADH, lactate or glycerol-3-phosphate to 80--90%. 3. The inhibitory effects of amytal and rotenone on NADH oxidation, but not on the oxidation of the other substrates, indicated the presence of the NADH dehydrogenase complex, or "site I region", in the electron transport system of P. shermanii. 4. NQNO inhibited substrate oxidations by oxygen and fumarate, as well as equilibration of the flavoproteins of the substrate dehydrogenases by way of menaquinone. The inhibition occurred at low concentrations of the inhibitor and reached 80--100%, depending on the substrate tested. The site of inhibition of the respiratory activity was located between menaquinone and cytochrome b. In addition, inhibition of flavoprotein equilibration suggested that NQNO acted upon the electron transfer directed from menaquinol towards the acceptor to be reduced, either cytochrome b or the flavoproteins, which would include fumarate reductase. 5. In NQNO-inhibited particles, cytochrome b was not oxidized by oxygen-free fumarate, but readily oxidized by oxygen. It was concluded from this and the above evidence that the branching-point of the electron transport chain towards fumarate reductase was located at the menaquinone in P. shermanii. It was further concluded that all cytochromes were situated in the oxygen-linked branch of the chain, which formed a dead end of the system under anaerobic conditions. 6. Antimycin A inhibited only oxygen-linked reactions of the particles to about 50% at high concentrations

  9. Perfluorinated chemicals: Differential toxicity, inhibition of aromatase activity and alteration of cellular lipids in human placental cells

    Energy Technology Data Exchange (ETDEWEB)

    Gorrochategui, Eva; Pérez-Albaladejo, Elisabet [Department of Environmental Chemistry, IDAEA–CSIC, 08034 Barcelona, Catalonia (Spain); Casas, Josefina [Department of Biomedicinal Chemistry, IQAC–CSIC, 08034 Barcelona, Catalonia (Spain); Lacorte, Sílvia, E-mail: slbqam@cid.csic.es [Department of Environmental Chemistry, IDAEA–CSIC, 08034 Barcelona, Catalonia (Spain); Porte, Cinta, E-mail: cinta.porte@cid.csic.es [Department of Environmental Chemistry, IDAEA–CSIC, 08034 Barcelona, Catalonia (Spain)

    2014-06-01

    The cytotoxicity of eight perfluorinated chemicals (PFCs), namely, perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorododecanoic acid (PFDoA), perfluorobutanesulfonate (PFBS), perfluorohexanesulfonate (PFHxS) and perfluorooctanesulfonate (PFOS) was assessed in the human placental choriocarcinoma cell line JEG-3. Only the long chain PFCs – PFOS, PFDoA, PFNA, PFOA – showed significant cytotoxicity in JEG-3 cells with EC50 values in the range of 107 to 647 μM. The observed cytotoxicity was to some extent related to a higher uptake of the longer chain PFCs by cells (PFDoA > PFOS ≫ PFNA > PFOA > PFHxA). Moreover, this work evidences a high potential of PFOS, PFOA and PFBS to act as aromatase inhibitors in placental cells with IC50s in the range of 57–80 μM, the inhibitory effect of PFBS being particularly important despite the rather low uptake of the compound by cells. Finally, exposure of JEG-3 cells to a mixture of the eight PFCs (0.6 μM each) led to a relative increase (up to 3.4-fold) of several lipid classes, including phosphatidylcholines (PCs), plasmalogen PC and lyso plasmalogen PC, which suggests an interference of PFCs with membrane lipids. Overall, this work highlights the ability of the PFC mixture to alter cellular lipid pattern at concentrations well below those that generate toxicity, and the potential of the short chain PFBS, often considered a safe substitute of PFOS, to significantly inhibit aromatase activity in placental cells. - Highlights: • Eight perfluorinated chemicals of different chain lengths have been selected. • Long chain ones – PFOS, PFDoA, PFNA, PFOA – were cytotoxic in placenta cells. • The uptake of long chain perfluorinated chemicals by cells was comparatively higher. • PFOS, PFOA and the short chain PFBS significantly inhibited aromatase activity. • A mixture of perfluorinated chemicals significantly altered placenta cell

  10. Investigation of chemical and physical properties of carbon nanotubes and their effects on cell biomechanics

    Science.gov (United States)

    Dong, Chenbo

    Carbon nanotubes (CNTs) are used for a variety of applications from nanocircuits, to hydrogen storage devices, and from designing optical fibers to forming conductive plastics. Recently, their functionalization with biomolecules led to exciting biological and biomedical applications in drug delivery or bioimaging. However, because of CNTs interactions with biological systems and their ability to translocate and persist into the circulatory and lymphatic systems and biological tissues, concerns about CNTs intrinsic toxicity have risen. It is thus necessary to develop and implement sensitive analysis technologies that allow investigation of CNTs toxicity upon uptake into a biological system. This thesis provides a comprehensive guide of experiments that have been performed during my Ph.D. tenure at West Virginia University in the Department of Chemical Engineering, in the group of Prof. Cerasela Zoica Dinu. Briefly: Chapter one presents a systematic study of the CNTs physical and chemical properties and how these properties are changed upon exposure to chemical agents normally used during their cleaning and purification processes. Also, this chapter shows how acid oxidation treatment leads to improved CNTs biocompatibility. Specifically, by incubating CNTs in a strong acid mixture we created a user-defined library of CNTs samples with different characteristics as recorded using Raman energy dispersive x-ray spectroscopy, atomic force microscopy, or solubility tests. Systematically characterized CNTs were subsequently tested for their biocompatibility in relation to human epithelial cells or enzymes. Such selected examples are building pertinent relationships between CNTs biocompatibility and their intrinsic properties by showing that acid oxidation treatment lowers CNTs toxicity making CNTs feasible platforms to be used for biomedical applications or the next generation of biosensors. (Publication: Chenbo Dong, Alan S Campell, Reem Eldawud, Gabriela Perhinschi, and

  11. In vitro toxicity of polycyclic aromatic hydrocarbons and halogenated aromatic hydrocarbons to cetacean cells and tissues

    Energy Technology Data Exchange (ETDEWEB)

    Carvan, M.J. III.

    1993-01-01

    Cetaceans bioaccumulate high aromatic hydrocarbon tissue residues, and elevated levels of PCB residues in tissues are proposed to have occurred concurrently with recent epizootic deaths of dolphins. The objectives of this study were: (1) to develop and characterize an epithelial cell line derived from dolphin tissues, (2) to investigate the effects of hydrocarbon pollutants on those cells, and (3) to analyze the toxicity of hydrocarbon pollutants on cetacean tissues in vitro. An epithelial cell line, Carvan dolphin kidney (CDK), isolated from a spontaneously aborted female bottlenose dolphin, Tursiops truncatus, grew rapidly. These cells were neither transformed nor immortal. Velocity sedimentation analysis showed CDK cells contained nuclear aryl hydrocarbon receptor, suggestive of cytochrome P450 inducibility. BaP inhibited mitosis in CDK cells in a dose-dependent manner. Data indicate that CDK cells metabolize BaP, that BaP metabolites bind to cellular DNA initiating unscheduled DNA synthesis, and that the inhibition of cytochrome P450 metabolism decrease the BaP-associated inhibition of mitosis in dolphin cells. The data also suggest that TCDD acts synergistically to increase the levels of DNA damage by the procarcinogen BaP. Cetacean liver microsomes was isolated and evaluated for the presence of cytochrome P450 proteins by SDS-PAGE, apparent minimum molecular weight determination, and immunoblot analysis. P450 activity was induced in cetacean tissue samples and CDK cells by exposure in vitro to one of several cytochrome P450-inducing chemicals. The data suggest that cetacean tissues and cells can be utilized to study the in vitro induction of cytochrome P450, resultant metabolism of xenobiotic contaminants, and the subsequent cellular and molecular responses. However, the identity of specific P450 isozymes involved in this process will remain undetermined until monoclonal antibodies that recognize cetacean P450s can be generated.

  12. An international validation study of a Bhas 42 cell transformation assay for the prediction of chemical carcinogenicity.

    Science.gov (United States)

    Sakai, Ayako; Sasaki, Kiyoshi; Hayashi, Kumiko; Muramatsu, Dai; Arai, Shoko; Endou, Nobuko; Kuroda, Sachiko; Poth, Albrecht; Bohnenberger, Susanne; Kunkelmann, Thorsten; Asakura, Masumi; Hirose, Hideki; Ishii, Nana; Mizuhashi, Fukutaro; Kasamoto, Sawako; Nagai, Miho; Pant, Kamala; Bruce, Shannon W; Sly, Jamie E; Yamazaki, Shojiro; Umeda, Makoto; Tanaka, Noriho

    2011-10-09

    The Bhas 42 cell transformation assay is a sensitive short-term system for predicting chemical carcinogenicity. Bhas 42 cells were established from BALB/c 3T3 cells by the transfection of v-Ha-ras gene and postulated to have acquired an initiated state in the two-stage carcinogenesis theory. The Bhas 42 cell transformation assay is capable of detecting both tumor-initiating and tumor-promoting activities of chemical carcinogens. The full assay protocol consists of two components, the initiation assay and the promotion assay, to detect the initiating activity and the promoting activity, respectively. An international study was carried out to validate this cell transformation assay in which six laboratories from three countries participated. Twelve coded chemicals were examined in total and each chemical was tested by three laboratories. In the initiation assay, concordant results were obtained by three laboratories for eight out of ten chemicals and in the promotion assay, concordant results were achieved for ten of twelve chemicals. The positive results were obtained in all three laboratories with the following chemicals: 2-acetylaminofluorene was positive in both initiation and promotion assays; dibenz[a,h]anthracene was positive in the initiation assay; sodium arsenite, lithocholic acid, cadmium chloride, mezerein and methapyrilene hydrochloride were positive in the promotion assay. o-Toluidin hydrochloride was positive in the both assays in two of the three laboratories. d-Mannitol, caffeine and l-ascorbic acid were negative in both assays in all the laboratories, and anthracene was negative in both assays in two of the three laboratories except one laboratory obtaining positive result in the promotion assay. Consequently, the Bhas 42 cell transformation assay correctly discriminated all six carcinogens and two tumor promoters from four non-carcinogens. Thus, the present study demonstrated that the Bhas 42 cell transformation assay is transferable and

  13. Wet-chemical passivation and characterization of silicon interfaces for solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Angermann, H.; Henrion, W.; Rebien, M. [Hahn-Meitner-Institut Berlin, Abt. Silizium-Photovoltaik, Kekulestrasse 5, D-12489 Berlin (Germany); Roseler, A. [Institut fur Spektrochemie und angewandte Spektroskopie, Albert-Einstein-Str. 9, D-12489 Berlin (Germany)

    2004-07-01

    The interface properties of silicon solar cell structures were characterized by the two non-destructive and highly surface-sensitive spectroscopic techniques: surface photovoltage and spectroscopic ellipsometry. The resulting charge and density of interface states as well as the microscopic surface roughness and oxide coverage were investigated during silicon wafer preparation and during sample storage in air. The surface state density of hydrogen-terminated silicon surfaces as well as the long-time stability of the hydrogen termination were found to primarily depend on the surface morphology resulting from the wet-chemical oxidation procedures applied before. The smallest interface state densities were obtained by NH{sub 4}F treatment subsequent to oxidation in ultra-pure water at 80C. Surfaces prepared using this procedure are found to be much more stable upon exposition to clean-room air than those prepared by conventionally prepared H-terminated surfaces. The successful application of the new passivation procedures in photovoltaics is shown for selected examples of different solar cell concepts.

  14. A single-cell model of PIP3 dynamics using chemical dimerization.

    Science.gov (United States)

    MacNamara, Aidan; Stein, Frank; Feng, Suihan; Schultz, Carsten; Saez-Rodriguez, Julio

    2015-06-15

    Most cellular processes are driven by simple biochemical mechanisms such as protein and lipid phosphorylation, but the sum of all these conversions is exceedingly complex. Hence, intuition alone is not enough to discern the underlying mechanisms in the light of experimental data. Toward this end, mathematical models provide a conceptual and numerical framework to formally evaluate the plausibility of biochemical processes. To illustrate the use of these models, here we built a mechanistic computational model of PI3K (phosphatidylinositol 3-kinase) activity, to determine the kinetics of lipid metabolizing enzymes in single cells. The model is trained to data generated upon perturbation with a reversible small-molecule based chemical dimerization system that allows for the very rapid manipulation of the PIP3 (phosphatidylinositol 3,4,5-trisphosphate) signaling pathway, and monitored with live-cell microscopy. We find that the rapid relaxation system used in this work decreased the uncertainty of estimating kinetic parameters compared to methods based on in vitro assays. We also examined the use of Bayesian parameter inference and how the use of such a probabilistic method gives information on the kinetics of PI3K and PTEN activity. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Porous silicon formation by HF chemical etching for antireflection of solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Yae, Shinji [Department of Materials Science and Chemistry, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2201 (Japan); CREST, JST, 4-1-8 Honcho, Kawaguchi, Saitama 322-0012 (Japan); Tanaka, Hiroyuki [Department of Material Engineering, Himeji Institute of Technology, 2167 Shosha, Himeji, Hyogo 671-2201 (Japan); Kobayashi, Tsutomu; Fukumuro, Naoki; Matsuda, Hitoshi [Department of Materials Science and Chemistry, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2201 (Japan)

    2005-06-01

    Macroporous and luminescent nanoporous Si are formed on Si wafers, which are modified with fine metal particles, by simply immersing the wafers in a HF solution without a bias or an oxidizing agent. The metal particles are deposited onto n-Si wafers by electroless displacement deposition from a metal salt solution including HF. The etching of Si consists of a local cathode reduction of oxygen and a local anode oxidation of Si. The porous layer is formed only on the metal-particle-deposited area of the Si wafers. The etching rate and surface morphology of Si change with the etching conditions such as dissolved oxygen concentration, kinds of metal particles, and photoillumination intensity during etching. The micrometer-sized macroporous Si layer is effective for the antireflection of solar cells. Efficient photoelectrochemical solar cells can be prepared by entire chemical modification of the n-Si surface. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Chemical reactivities of bleomycin.

    Science.gov (United States)

    Padbury, G; Sligar, S S

    1985-07-05

    Ferric bleomycin was tested for its ability to catalyze a set of six oxidative reactions characteristic of the heme-containing proteins, cytochrome P-450 and chloroperoxidase. These reactions included peroxyacid decarboxylation and aliphatic hydroxylation as typical cytochrome P-450 chemistries. Peroxyacid-supported oxygen evolution and hydrogen peroxide-mediated chlorination were utilized as characteristic chloroperoxidase reactivities. A typical peroxidative reaction and heteroatom dealkylation, common to both O2 activating enzymes, were also studied. Bleomycin was found to catalyze peroxidation of o-dianisidine. The ferric drug complex was found competent in carrying out N-demethylation of N,N-dimethylaniline when peroxides or peroxyacids or iodosobenzene were used as the oxidants. N-Demethylation was not achieved when N,N-dimethylaniline-N-oxide was substituted as the oxidant under similar conditions. Hydroxylation of cumene and decarboxylation of phenylperacetic acid were not found to be catalyzed by bleomycin. Oxygen evolution from m-chloroperbenzoic acid and chlorination of monochlorodimedone from chloride ion and hydrogen peroxide were found to be catalyzed by bleomycin. Cytochrome P-450cam was also evaluated for O2 evolution, and halogenation activity and was found not to demonstrate such reactivities. The results of this initial survey, along with those of previous studies, appear to indicate that the chemical reactivity of bleomycin can be more closely aligned with the reactivities demonstrated by chloroperoxidase than those of cytochrome P-450.

  17. An inducible NADPH-cytochrome P450 reductase from Picrorhiza kurrooa - an imperative redox partner of cytochrome P450 enzymes.

    Science.gov (United States)

    Bhat, Wajid Waheed; Rana, Satiander; Dhar, Niha; Razdan, Sumeer; Pandith, Shahzad A; Vishwakarma, Ram; Lattoo, Surrinder K

    2014-06-01

    Picrorhiza kurrooa synthesizes a large array of pharmacologically important monoterpenoid iridoid glycosides called picrosides. Although chemical profile and pharmacological activities of P. kurrooa have been extensively studied, limited attempts have been made to decipher the biosynthetic route and to identify the key regulatory genes involved in picroside biosynthesis. In the present study, NADPH-cytochrome P450 reductase, a key enzyme involved in electron transfer to cytochrome P450s was identified from P. kurrooa. The full length cDNA (2679 bp) contained an open reading frame of 2133 bp, corresponding to 710 amino acids. PkCPR was heterologously expressed in Escherichia coli and the kinetic parameters of the recombinant enzyme were determined. Specific activity, V max and K m of PkCPR were found to be 5.8 ± 0.05 μmol min(-1) mg(-1), 8.1 ± 0.12 μmol min(-1) mg(-1) and 7.8 μM, respectively. PkCPR was found to be spatially regulated at transcript level, being maximally expressed in leaf tissues. Altitude was found to have a positive effect on the picroside concentration and the picroside content positively correlated with the PkCPR transcript levels in samples collected at varied altitudes. Further, transcript profiling under methyl jasmonate, salicylic acid, 2,4-dicholorophenoxy acetic acid and UV-B elicitations displayed differential transcriptional regulation of PkCPR that fully corroborated with the identified cis-elements within the PkCPR promoter. Expression of PkCPR was inducible by UV-B and phytohormone elicitation, indicating that the PkCPR is possibly related to defence reactions, including biosynthesis of secondary metabolites. Present study is so far the only report of identification and functional characterization of CPR ortholog from P. kurrooa.

  18. Evaluation of chemical fluorescent dyes as a protein conjugation partner for live cell imaging.

    Directory of Open Access Journals (Sweden)

    Yoko Hayashi-Takanaka

    Full Text Available To optimize live cell fluorescence imaging, the choice of fluorescent substrate is a critical factor. Although genetically encoded fluorescent proteins have been used widely, chemical fluorescent dyes are still useful when conjugated to proteins or ligands. However, little information is available for the suitability of different fluorescent dyes for live imaging. We here systematically analyzed the property of a number of commercial fluorescent dyes when conjugated with antigen-binding (Fab fragments directed against specific histone modifications, in particular, phosphorylated H3S28 (H3S28ph and acetylated H3K9 (H3K9ac. These Fab fragments were conjugated with a fluorescent dye and loaded into living HeLa cells. H3S28ph-specific Fab fragments were expected to be enriched in condensed chromosomes, as H3S28 is phosphorylated during mitosis. However, the degree of Fab fragment enrichment on mitotic chromosomes varied depending on the conjugated dye. In general, green fluorescent dyes showed higher enrichment, compared to red and far-red fluorescent dyes, even when dye:protein conjugation ratios were similar. These differences are partly explained by an altered affinity of Fab fragment after dye-conjugation; some dyes have less effect on the affinity, while others can affect it more. Moreover, red and far-red fluorescent dyes tended to form aggregates in the cytoplasm. Similar results were observed when H3K9ac-specific Fab fragments were used, suggesting that the properties of each dye affect different Fab fragments similarly. According to our analysis, conjugation with green fluorescent dyes, like Alexa Fluor 488 and Dylight 488, has the least effect on Fab affinity and is the best for live cell imaging, although these dyes are less photostable than red fluorescent dyes. When multicolor imaging is required, we recommend the following dye combinations for optimal results: Alexa Fluor 488 (green, Cy3 (red, and Cy5 or CF640 (far-red.

  19. Fucoxanthin Attenuates Rifampin-Induced Cytochrome P450 3A4 (CYP3A4 and Multiple Drug Resistance 1 (MDR1 Gene Expression Through Pregnane X Receptor (PXR-Mediated Pathways in Human Hepatoma HepG2 and Colon Adenocarcinoma LS174T Cells

    Directory of Open Access Journals (Sweden)

    Miao-Lin Hu

    2012-01-01

    Full Text Available Pregnane X receptor (PXR has been reported to regulate the expression of drug-metabolizing enzymes, such as the cytochrome P450 3A (CYP3A family and transporters, such as multiple drug resistance 1 (MDR1. Fucoxanthin, the major carotenoid in brown sea algae, is a putative chemopreventive agent. In this study, we determined whether fucoxanthin could overcome drug resistance through attenuation of rifampin-induced CYP3A4 and MDR1 gene expression by PXR-mediated pathways in HepG2 hepatoma cells. We found that fucoxanthin (1–10 μM significantly attenuated rifampin (20 μM-induced CYP3A4, MDR1 mRNA and CYP3A4 protein expression at 24 h of incubation. Mechanistically, fucoxanthin strongly attenuated the PXR-mediated CYP3A4 promoter activity in HepG2 cells. In addition, fucoxanthin attenuated constitutive androstane receptor (CAR- and rPXR-mediated CYP3A4 promoter activity in this cell line. Using the mammalian two-hybrid assay, we found that fucoxanthin significantly decreased the interaction between PXR and SRC-1, a PXR co-activator. Thus, fucoxanthin can decrease rifampin-induced CYP3A4 and MDR1 expression through attenuation of PXR-mediated CYP3A4 promoter activation and interaction between PXR and co-activator. These findings could lead to potentially important new therapeutic and dietary approaches to reduce the frequency of adverse drug reactions.

  20. Chemically-Induced RAT Mesenchymal Stem Cells Adopt Molecular Properties of Neuronal-Like Cells but Do Not Have Basic Neuronal Functional Properties

    Science.gov (United States)

    Calcagnotto, Maria E.; Motta, Fabiana L.; Martinez, Gilberto; de Oliveira, Allan C.; Keim, Leda M. N.; D'Almeida, Vânia; Mendez-Otero, Rosália; Mello, Luiz E.

    2009-01-01

    Induction of adult rat bone marrow mesenchymal stem cells (MSC) by means of chemical compounds (β-mercaptoethanol, dimethyl sulfoxide and butylated hydroxyanizole) has been proposed to lead to neuronal transdifferentiation, and this protocol has been broadly used by several laboratories worldwide. Only a few hours of MSC chemical induction using this protocol is sufficient for the acquisition of neuronal-like morphology and neuronal protein expression. However, given that cell death is abundant, we hypothesize that, rather than true neuronal differentiation, this particular protocol leads to cellular toxic effects. We confirm that the induced cells with neuronal-like morphology positively stained for NF-200, S100, β-tubulin III, NSE and MAP-2 proteins. However, the morphological and molecular changes after chemical induction are also associated with an increase in the apoptosis of over 50% of the plated cells after 24 h. Moreover, increased intracellular cysteine after treatment indicates an impairment of redox circuitry during chemical induction, and in vitro electrophysiological recordings (patch-clamp) of the chemically induced MSC did not indicate neuronal properties as these cells do not exhibit Na+ or K+ currents and do not fire action potentials. Our findings suggest that a disruption of redox circuitry plays an important role in this specific chemical induction protocol, which might result in cytoskeletal alterations and loss of functional ion-gated channels followed by cell death. Despite the neuronal-like morphology and neural protein expression, induced rat bone marrow MSC do not have basic functional neuronal properties, although it is still plausible that other methods of induction and/or sources of MSC can achieve a successful neuronal differentiation in vitro. PMID:19370156

  1. Tandem solar cells deposited using hot-wire chemical vapor deposition

    Science.gov (United States)

    van Veen, M. K.

    2003-05-01

    In this thesis, the application of the hot-wire chemical vapor deposition (HWCVD) technique for the deposition of silicon thin films is described. The HWCVD technique is based on the dissociation of silicon-containing gasses at the catalytic surface of a hot filament. Advantages of this technique are the high deposition rate, the low equipment costs, and the scalability. The main goal of this thesis is the optimization of the material properties of both hydrogenated amorphous silicon and microcrystalline silicon, so that these materials can be incorporated as the absorbing layers in tandem solar cells. Firstly, the influence of specific deposition parameters on the material quality of hydrogenated amorphous silicon was investigated. With the use of tantalum filaments, the deposition temperature could be decreased to moderate temperatures, while the (electronic) properties of the amorphous silicon were improved. However, at these low filament temperatures the silicide formation at the filaments was enhanced, resulting in a decrease in the deposition rate and a deterioration of the material quality over time. For extensive silicide formation, even epitaxial growth on crystalline wafers was observed. By preheating the filaments at elevated temperature before deposition, the influence of silicide formation could be minimized, which resulted in an improvement in the reproducibility of the material quality. Solar cells, in which the absorbing layer was made at moderate temperature, had high open-circuit voltages and high fill factors. The best n-i-p structured cell on plain stainless steel had an initial efficiency of 7.2 %. The incorporation of amorphous silicon in p-i-n structured cells with a textured front contact resulted in a higher short-circuit current density and a higher efficiency. Occasionally, many n-i-p structured cells showed shunting problems. The number of working cells was directly correlated to the age of the filaments. The presence of silicides on the

  2. Circulating cytochrome c as potential biomarker of impaired reperfusion in ST-segment elevation acute myocardial infarction.

    Science.gov (United States)

    Marenzi, Giancarlo; Giorgio, Marco; Trinei, Mirella; Moltrasio, Marco; Ravagnani, Paolo; Cardinale, Daniela; Ciceri, Fabio; Cavallero, Annalisa; Veglia, Fabrizio; Fiorentini, Cesare; Cipolla, Carlo M; Bartorelli, Antonio L; Pelicci, Piergiuseppe

    2010-11-15

    In patients with ST-segment elevation acute myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (pPCI), abrupt reperfusion can induce myocardial injury and apoptotic cell death. Reperfusion-induced myocardial damage, however, cannot be easily evaluated in clinical practice because of the lack of specific biomarkers. Cytochrome c, a mitochondrial protein, is released on reperfusion into the cytosol, where it triggers the apoptotic process. It can reach the external fluid and circulating blood when cell rupture occurs. We measured the cytochrome c circulating levels in patients with STEMI undergoing pPCI, and correlated them with the clinical signs of myocardial necrosis and reperfusion. The plasma creatine kinase-MB mass and serum cytochrome c (enzyme-linked immunosorbent assay method) were serially measured in 55 patients with STEMI undergoing pPCI. The angiographic and electrocardiographic signs of myocardial reperfusion were also assessed. Cytochrome c transiently increased in all patients with STEMI, with a curve that paralleled that of creatine kinase-MB. A significant relation was found between the peak values of the 2 biomarkers (R = 0.35, p = 0.01) and between the areas under the 2 curves (R = 0.33, p = 0.02). The creatine kinase-MB peak value correlated significantly with the clinical features of infarct extension. In contrast, the cytochrome c peak value correlated inversely with the myocardial blush grade. Patients with clinical signs of myocardial reperfusion injury had a significantly greater cytochrome c peak value than patients without reperfusion injury (median 1.65 ng/ml, interquartile range 1.20 to 2.20, vs 1.1 ng/ml, interquartile range 0.65 to 1.55; p = 0.04). In conclusion, serum cytochrome c is detectable in the early phase of STEMI treated with pPCI and is associated with clinical signs of impaired myocardial reperfusion. Copyright © 2010 Elsevier Inc. All rights reserved.

  3. Purification of cytochrome P450 from filamentous fungus Rhyzopus nigricans.

    Science.gov (United States)

    Makovec, T; Breskvar, K

    2000-01-01

    It has been reported in our previous studies that steroid hydroxylation system of Rhizopus nigricans involves cytochrome P450 and NADPH-cytochrome P450 reductase in the electron transport system. Both enzymes are membrane bound and are located in the microsomal preparations of progesterone induced fungal mycelia. In order to identify and characterize the cytochrome P450 component of fungal monoxygenase system, microsomal proteins from induced mycelia were subjected to HIGH Q anion exchange and MONO P (FPLC) anion exchange chromatography. Four fractions containing cytochrome P450 have been resolved on MONO P column. They exhibit CO difference spectra and type II difference spectra with ketoconazole.

  4. Cytochrome P450 Activity in Ex Vivo Cornea Models and a Human Cornea Construct.

    Science.gov (United States)

    Kölln, Christian; Reichl, Stephan

    2016-07-01

    The pharmacokinetic behaviors of novel ophthalmic drugs are often preliminarily investigated in preclinical studies using ex vivo animal cornea or corneal cell culture models. During transcorneal passage, topically applied drugs may be affected by drug metabolizing enzymes. The knowledge regarding the functional expression of metabolic enzymes in corneal tissue is marginal; thus, the aim of this study was to investigate cytochrome P450 activity in an organotypic three-dimensional human cornea construct and to compare it with porcine and rabbit corneas, which are commonly used ex vivo cornea models. The total cytochrome P450 activity was determined by measuring the transformation of 7-ethoxycoumarin. Furthermore, the expression of the cytochrome P450 enzyme 2D6 (CYP2D6) was investigated at the protein level using immunohistochemistry and western blotting. CYP2D6 activity measurements were performed using a d-luciferin-based assay. In summary, similar levels of the total cytochrome P450 activity were identified in all 3 cornea models. The protein expression of CYP2D6 was confirmed in the human cornea construct and porcine cornea, whereas the signals in the rabbit cornea were weak. The analysis of the CYP2D6 activity indicated similar values for the human cornea construct and porcine cornea; however, a distinctly lower activity was observed in the rabbit cornea. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  5. Respiratory cytochrome c oxidase can be efficiently reduced by the photosynthetic redox proteins cytochrome c6 and plastocyanin in cyanobacteria.

    Science.gov (United States)

    Navarro, José A; Durán, Raúl V; De la Rosa, Miguel A; Hervás, Manuel

    2005-07-04

    Plastocyanin and cytochrome c6 are two small soluble electron carriers located in the intrathylacoidal space of cyanobacteria. Although their role as electron shuttle between the cytochrome b6f and photosystem I complexes in the photosynthetic pathway is well established, their participation in the respiratory electron transport chain as donors to the terminal oxidase is still under debate. Here, we present the first time-resolved analysis showing that both cytochrome c6 and plastocyanin can be efficiently oxidized by the aa3 type cytochrome c oxidase in Nostoc sp. PCC 7119. The apparent electron transfer rate constants are ca. 250 and 300 s(-1) for cytochrome c6 and plastocyanin, respectively. These constants are 10 times higher than those obtained for the oxidation of horse cytochrome c by the oxidase, in spite of being a reaction thermodynamically more favourable.

  6. Noble metal-free hydrazine fuel cell catalysts: EPOC effect in competing chemical and electrochemical reaction pathways.

    Science.gov (United States)

    Sanabria-Chinchilla, Jean; Asazawa, Koichiro; Sakamoto, Tomokazu; Yamada, Koji; Tanaka, Hirohisa; Strasser, Peter

    2011-04-13

    We report the discovery of a highly active Ni-Co alloy electrocatalyst for the oxidation of hydrazine (N(2)H(4)) and provide evidence for competing electrochemical (faradaic) and chemical (nonfaradaic) reaction pathways. The electrochemical conversion of hydrazine on catalytic surfaces in fuel cells is of great scientific and technological interest, because it offers multiple redox states, complex reaction pathways, and significantly more favorable energy and power densities compared to hydrogen fuel. Structure-reactivity relations of a Ni(60)Co(40) alloy electrocatalyst are presented with a 6-fold increase in catalytic N(2)H(4) oxidation activity over today's benchmark catalysts. We further study the mechanistic pathways of the catalytic N(2)H(4) conversion as function of the applied electrode potential using differentially pumped electrochemical mass spectrometry (DEMS). At positive overpotentials, N(2)H(4) is electrooxidized into nitrogen consuming hydroxide ions, which is the fuel cell-relevant faradaic reaction pathway. In parallel, N(2)H(4) decomposes chemically into molecular nitrogen and hydrogen over a broad range of electrode potentials. The electroless chemical decomposition rate was controlled by the electrode potential, suggesting a rare example of a liquid-phase electrochemical promotion effect of a chemical catalytic reaction ("EPOC"). The coexisting electrocatalytic (faradaic) and heterogeneous catalytic (electroless, nonfaradaic) reaction pathways have important implications for the efficiency of hydrazine fuel cells. © 2011 American Chemical Society

  7. Hot-Wire Chemical Vapor Deposition Of Polycrystalline Silicon : From Gas Molecule To Solar Cell

    Science.gov (United States)

    van Veenendaal, P. A. T. T.

    2002-10-01

    Although the effort to investigate the use of renewable energy sources, such as wind and solar energy, has increased, their contribution to the total energy consumption remains insignificant. The conversion of solar energy into electricity through solar cells is one of the most promising techniques, but the use of these cells is limited by the high cost of electricity. The major contributions to these costs are the material and manufacturing costs. Over the past decades, the development of silicon based thin film solar cells has received much attention, because the fabrication costs are low. A promising material for use in thin film solar cells is polycrystalline silicon (poly-Si:H). A relatively new technique to deposit poly-Si:H is Hot-Wire Chemical Vapor Deposition (Hot-Wire CVD), in which the reactant gases are catalytically decomposed at the surface of a hot filament, mainly tungsten and tantalum. The main advantages of Hot-Wire CVD over PE-CVD are absence of ion bombardment, high deposition rate, low equipment cost and high gas utilization. This thesis deals with the full spectrum of deposition, characterization and application of poly-Si:H thin films, i.e. from gas molecule to solar cell. Studies on the decomposition of silane on the filament showed that the process is catalytic of nature and that silane is decomposed into Si and 4H. The dominant gas phase reaction is the reaction of Si and H with silane, resulting in SiH3, Si2H6, Si3H6 and H2SiSiH2. The film growth precursors are Si, SiH3 and Si2H4. Also, XPS results on used tantalum and tungsten filaments are discussed. The position dependent measurements show larger silicon contents at the ends of the tungsten filament, as compared to the middle, due to a lower filament temperature. This effect is insignificant for a tantalum filament. Deposition time dependent measurements show an increase in silicon content of the tungsten filament with time, while the silicon content on the tantalum filament saturates

  8. The Folding Energy Landscape and Free Energy Excitations of Cytochrome c

    Science.gov (United States)

    Weinkam, Patrick; Zimmermann, Jörg; Romesberg, Floyd E.

    2014-01-01

    The covalently bound heme cofactor plays a dominant role in the folding of cytochrome c. Due to the complicated inorganic chemistry of the heme, some might consider the folding of cytochrome c to be a special case that follows different principles than those used to describe folding of proteins without cofactors. Recent investigations, however, demonstrate that models which are commonly used to describe folding for many proteins work well for cytochrome c when heme is explicitly introduced and generally provide results that agree with experimental observations. We will first discuss results from simple native structure-based models. These models include attractive interactions between nonadjacent residues only if they are present in the crystal structure at pH 7. Since attractive nonnative contacts are not included in native structure-based models, their energy landscapes can be described as “perfectly funneled.” In other words, native structure-based models are energetically guided towards the native state and contain no energetic traps that would hinder folding. Energetic traps are sources of frustration which cause specific transient intermediates to be populated. Native structure-based models do include repulsion between residues due to excluded volume. Nonenergetic traps can therefore exist if the chain, which cannot cross over itself, must partially unfold in order for folding to proceed. The ability of native structure-based models to capture these type of motions is in part responsible for their successful predictions of folding pathways for many types of proteins. Models without frustration describe well the sequence of folding events for cytochrome c inferred from hydrogen exchange experiments thereby justifying their use as a starting point. At low pH, the folding sequence of cytochrome c deviates from that at pH 7 and from those predicted from models with perfectly funneled energy landscapes. Alternate folding pathways are a result of “chemical

  9. Human Pluripotent Stem Cell Based Developmental Toxicity Assays for Chemical Safety Screening and Systems Biology Data Generation.

    Science.gov (United States)

    Shinde, Vaibhav; Klima, Stefanie; Sureshkumar, Perumal Srinivasan; Meganathan, Kesavan; Jagtap, Smita; Rempel, Eugen; Rahnenführer, Jörg; Hengstler, Jan Georg; Waldmann, Tanja; Hescheler, Jürgen; Leist, Marcel; Sachinidis, Agapios

    2015-06-17

    Efficient protocols to differentiate human pluripotent stem cells to various tissues in combination with -omics technologies opened up new horizons for in vitro toxicity testing of potential drugs. To provide a solid scientific basis for such assays, it will be important to gain quantitative information on the time course of development and on the underlying regulatory mechanisms by systems biology approaches. Two assays have therefore been tuned here for these requirements. In the UKK test system, human embryonic stem cells (hESC) (or other pluripotent cells) are left to spontaneously differentiate for 14 days in embryoid bodies, to allow generation of cells of all three germ layers. This system recapitulates key steps of early human embryonic development, and it can predict human-specific early embryonic toxicity/teratogenicity, if cells are exposed to chemicals during differentiation. The UKN1 test system is based on hESC differentiating to a population of neuroectodermal progenitor (NEP) cells for 6 days. This system recapitulates early neural development and predicts early developmental neurotoxicity and epigenetic changes triggered by chemicals. Both systems, in combination with transcriptome microarray studies, are suitable for identifying toxicity biomarkers. Moreover, they may be used in combination to generate input data for systems biology analysis. These test systems have advantages over the traditional toxicological studies requiring large amounts of animals. The test systems may contribute to a reduction of the costs for drug development and chemical safety evaluation. Their combination sheds light especially on compounds that may influence neurodevelopment specifically.

  10. Assessing chemical exposure and ecological impacts of environmental surface waters using cell culture-based metabolomic

    Science.gov (United States)

    Waste water treatment plants (WWTPs), as well as industrial and agricultural operations release complex mixtures of anthropogenic chemicals that negatively affect surface water quality. Previous studies have shown that exposure to such complex chemical mixtures can produce adver...

  11. Chemical biology-based approaches on fluorescent labeling of proteins in live cells.

    Science.gov (United States)

    Jung, Deokho; Min, Kyoungmi; Jung, Juyeon; Jang, Wonhee; Kwon, Youngeun

    2013-05-01

    Recently, significant advances have been made in live cell imaging owing to the rapid development of selective labeling of proteins in vivo. Green fluorescent protein (GFP) was the first example of fluorescent reporters genetically introduced to protein of interest (POI). While GFP and various types of engineered fluorescent proteins (FPs) have been actively used for live cell imaging for many years, the size and the limited windows of fluorescent spectra of GFP and its variants set limits on possible applications. In order to complement FP-based labeling methods, alternative approaches that allow incorporation of synthetic fluorescent probes to target POIs were developed. Synthetic fluorescent probes are smaller than fluorescent proteins, often have improved photochemical properties, and offer a larger variety of colors. These synthetic probes can be introduced to POIs selectively by numerous approaches that can be largely categorized into chemical recognition-based labeling, which utilizes metal-chelating peptide tags and fluorophore-carrying metal complexes, and biological recognition-based labeling, such as (1) specific non-covalent binding between an enzyme tag and its fluorophore-carrying substrate, (2) self-modification of protein tags using substrate variants conjugated to fluorophores, (3) enzymatic reaction to generate a covalent binding between a small molecule substrate and a peptide tag, and (4) split-intein-based C-terminal labeling of target proteins. The chemical recognition-based labeling reaction often suffers from compromised selectivity of metal-ligand interaction in the cytosolic environment, consequently producing high background signals. Use of protein-substrate interactions or enzyme-mediated reactions generally shows improved specificity but each method has its limitations. Some examples are the presence of large linker protein, restriction on the choice of introducible probes due to the substrate specificity of enzymes, and competitive

  12. In vivo photo-detection of chemically induced premalignant lesions and squamous cell carcinoma of the rat palatal mucosa

    NARCIS (Netherlands)

    Nauta, JM; Speelman, OC; vanLeengoed, HLLM; Nikkels, PGJ; Roodenburg, JLN; Witjes, MJH; Vermey, A

    Photo-detection using in vivo fluorescence was studied for different stages of chemically induced premalignant lesions and squamous cell carcinoma (SCC) of the Wistar rat palatal mucosa. It was found that the epithelial dysplasia (numerically expressed in the epithelial atypia index (EAI)) of the

  13. 20161106 - Human Pluripotent Stem Cell-Based Assay Predicts Developmental Toxicity Potential of ToxCast Chemicals (ACT meeting)

    Science.gov (United States)

    Worldwide initiatives to screen for toxicity potential among the thousands of chemicals currently in use require inexpensive and high-throughput in vitro models to meet their goals. The devTOX quickPredict platform is an in vitro human pluripotent stem cell-based assay used to as...

  14. Developing predictions of in vivo developmental toxicity of ToxCast chemicals using mouse embryonic stem cells.

    Science.gov (United States)

    Developing predictions of in vivo developmental toxicity of ToxCast chemicals using mouse embryonic stem cells S. Hunter, M. Rosen, M. Hoopes, H. Nichols, S. Jeffay, K. Chandler1, Integrated Systems Toxicology Division, National Health and Environmental Effects Research Labor...

  15. Human Pluripotent Stem Cell-Based Assay Predicts Developmental Toxicity Potential of ToxCast Chemicals (ACT meeting)

    Science.gov (United States)

    Worldwide initiatives to screen for toxicity potential among the thousands of chemicals currently in use require inexpensive and high-throughput in vitro models to meet their goals. The devTOX quickPredict platform is an in vitro human pluripotent stem cell-based assay used to as...

  16. Chemically Defined and Xeno-Free Cryopreservation of Human Adipose-Derived Stem Cells.

    Directory of Open Access Journals (Sweden)

    Melany López

    Full Text Available The stromal compartment of adipose tissue harbors multipotent cells known as adipose-derived stem cells (ASCs. These cells can differentiate into various lineages including osteogenic, chrondrogenic, adipogenic, and neurogenic; this cellular fraction may be easily obtained in large quantities through a clinically safe liposuction procedure. Therefore, ASCs offer exceptional opportunities for tissue engineering and regenerative medicine. However, current practices involving ASCs typically use fetal bovine serum (FBS-based cryopreservation solutions that are associated with risks of immunological reactions and of transmitting infectious diseases and prions. To realize clinical applications of ASCs, serum- and xeno-free defined cryopreservation methods are needed. To this end, an animal product-free chemically defined cryopreservation medium was formulated by adding two antioxidants (reduced glutathione and ascorbic acid 2-phosphate, two polymers (PVA and ficoll, two permeating cryoprotectants (ethylene glycol and dimethylsulfoxide, a disaccharide (trehalose, and a calcium chelator (EGTA to HEPES-buffered DMEM/F12. To limit the number of experimental groups, the concentration of trehalose, both polymers, and EGTA was fixed while the presence of the permeating CPAs and antioxidants was varied. ASCs suspended either in different versions of the defined medium or in the conventional undefined cryopreservation medium (10% dimethylsulfoxide+10% DMEM/F12+80% serum were cooled to -70°C at 1°C/min before being plunged into liquid nitrogen. Samples were thawed either in air or in a water bath at 37°C. The presence of antioxidants along with 3.5% concentration of each penetrating cryoprotectant improved the freezing outcome to the level of the undefined cryopreservation medium, but the plating efficiency was still lower than that of unfrozen controls. Subsequently, increasing the concentration of both permeating cryoprotectants to 5% further improved the

  17. Transfection of isolated rainbow trout, Oncorhynchus mykiss, granulosa cells through chemical transfection and electroporation at 12°C.

    Science.gov (United States)

    Marivin, E; Mourot, B; Loyer, P; Rime, H; Bobe, J; Fostier, A

    2015-09-15

    Over-expression or inhibition of gene expression can be efficiently used to analyse the functions and/or regulation of target genes. Modulation of gene expression can be achieved through transfection of exogenous nucleic acids into target cells. Such techniques require the development of specific protocols to transfect cell cultures with nucleic acids. The aim of this study was to develop a method of transfection suitable for rainbow trout granulosa cells in primary culture. After the isolation of rainbow trout granulosa cells, chemical transfection of cells with a fluorescent morpholino oligonucleotide (MO) was tested using FuGENE HD at 12 °C. Electroporation was also employed to transfect these cells with either a plasmid or MO. Transfection was more efficient using electroporation (with the following settings: 1200 V/40 ms/1p) than chemical transfection, but electroporation by itself was deleterious, resulting in a decrease of the steroidogenic capacity of the cells, measured via estradiol production from its androgenic substrate. The disturbance of cell biology induced by the transfection method per se should be taken into account in data interpretation when investigating the effects of under- or over-expression of candidate genes. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Theory and Electrochemistry of Cytochrome c.

    Science.gov (United States)

    Seyedi, Salman S; Waskasi, Morteza M; Matyushov, Dmitry V

    2017-05-18

    Extensive simulations of cytochrome c in solution are performed to address the apparent contradiction between large reorganization energies of protein electron transfer typically reported by atomistic simulations and much smaller values produced by protein electrochemistry. The two sets of data are reconciled by deriving the activation barrier for electrochemical reaction in terms of an effective reorganization energy composed of half the Stokes shift (characterizing the medium polarization in response to electron transfer) and the variance reorganization energy (characterizing the breadth of electrostatic fluctuations). This effective reorganization energy is much smaller than each of the two components contributing to it and is fully consistent with electrochemical measurements. Calculations in the range of temperatures between 280 and 360 K combine long, classical molecular dynamics simulations with quantum calculations of the protein active site. The results agree with the Arrhenius plots for the reaction rates and with cyclic voltammetry of cytochrome c immobilized on self-assembled monolayers. Small effective reorganization energy, and the resulting small activation barrier, is a general phenomenology of protein electron transfer allowing fast electron transport within biological energy chains.

  19. Microbial electrolysis desalination and chemical-production cell for CO2 sequestration

    KAUST Repository

    Zhu, Xiuping

    2014-05-01

    Mineral carbonation can be used for CO2 sequestration, but the reaction rate is slow. In order to accelerate mineral carbonation, acid generated in a microbial electrolysis desalination and chemical-production cell (MEDCC) was examined to dissolve natural minerals rich in magnesium/calcium silicates (serpentine), and the alkali generated by the same process was used to absorb CO2 and precipitate magnesium/calcium carbonates. The concentrations of Mg2+ and Ca2+ dissolved from serpentine increased 20 and 145 times by using the acid solution. Under optimal conditions, 24mg of CO2 was absorbed into the alkaline solution and 13mg of CO2 was precipitated as magnesium/calcium carbonates over a fed-batch cycle (24h). Additionally, the MEDCC removed 94% of the COD (initially 822mg/L) and achieved 22% desalination (initially 35g/L NaCl). These results demonstrate the viability of this process for effective CO2 sequestration using renewable organic matter and natural minerals. © 2014 Elsevier Ltd.

  20. Some physico-chemical and serological properties of isolated protein components of red cell membranes

    Science.gov (United States)

    Poulik, M. D.; Lauf, P. K.

    1969-01-01

    Exposure of human red cell ghosts to low pH (pH 2–2·2) for 20–24 hr and extraction with a biphasic system (butanol–water) at acid pH yielded a water-phase material which was separated by gel filtration into two major fractions. Fraction A is of glycoprotein nature having a molecular weight of approximately 200,000 and exhibiting A, M and N antigen activity. Fraction B is primarily protein in nature having a molecular weight of about 50,000 to 60,000, and is practically devoid of A and MN antigens. The materials isolated were found heterogeneous by electrophoresis in urea starch gels. Peak A and peak B differed significantly with respect to number, mobility, and intensity of the separated components. The physico-chemical and serological properties of the water phase and its sub-fractions are discussed with respect to structural make-up of erythrocyte membrane. ImagesFIG. 2FIG. 3 PMID:5786811

  1. Formic acid production using a microbial electrolysis desalination and chemical-production cell.

    Science.gov (United States)

    Lu, Yaobin; Luo, Haiping; Yang, Kunpeng; Liu, Guangli; Zhang, Renduo; Li, Xiao; Ye, Bo

    2017-11-01

    The aim of this study was to investigate the feasibility and optimization of formic acid production in the microbial electrolysis desalination and chemical-production cell (MEDCC). The maximum current density in the MEDCC with 72cm of the anode fiber length (72-MEDCC) reached 24.0±2.0A/m2, which was much higher than previously reported. The maximum average formic acid production rate in the 72-MEDCC was 5.28 times higher than that in the MEDCC with 24cm of the anode fiber length (37.00±1.15vs. 7.00±0.25mg/h). High performance in the 72-MEDCC was attributed to small membrane spacing (1mm), high flow rate (1500μL/min) on the membrane surface and high anode biomass. The minimum electricity consumption of 0.34±0.04kWh/kg in the 72-MEDCC was only 3.1-18.8% of those in the EDBMs. The MEDCC should be a promising technology for the formic acid production. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Development and validation of a slurry model for chemical hydrogen storage in fuel cell vehicle applications

    Science.gov (United States)

    Brooks, Kriston P.; Pires, Richard P.; Simmons, Kevin L.

    2014-12-01

    The U.S. Department of Energy's (DOE) Hydrogen Storage Engineering Center of Excellence (HSECoE) is developing models for hydrogen storage systems for fuel cell-based light duty vehicle applications for a variety of promising materials. These transient models simulate the performance of the storage system for comparison to the DOE's Technical Targets and a set of four drive cycles. PNNL developed models to simulate the performance and suitability of slurry-based chemical hydrogen storage materials. The storage systems of both a representative exothermic system based on ammonia borane and an endothermic system based on alane were developed and modeled in Simulink®. Once complete, the reactor and radiator components of the model were validated with experimental data. The system design parameters were adjusted to allow the model to successfully meet a highway cycle, an aggressive cycle, a cold-start cycle, and a hot drive cycle. Finally, a sensitivity analysis was performed to identify the range of material properties where these DOE targets and drive cycles could be met. Materials with a heat of reaction >11 kJ mol-1 H2 generated and a slurry hydrogen capacity of >11.4% will meet the on-board efficiency and gravimetric capacity targets, respectively.

  3. Development and Validation of a Slurry Model for Chemical Hydrogen Storage in Fuel Cell Applications

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, Kriston P.; Pires, Richard P.; Simmons, Kevin L.

    2014-07-25

    The US Department of Energy's (DOE) Hydrogen Storage Engineering Center of Excellence (HSECoE) is developing models for hydrogen storage systems for fuel cell-based light duty vehicle applications for a variety of promising materials. These transient models simulate the performance of the storage system for comparison to the DOE’s Technical Targets and a set of four drive cycles. The purpose of this research is to describe the models developed for slurry-based chemical hydrogen storage materials. The storage systems of both a representative exothermic system based on ammonia borane and endothermic system based on alane were developed and modeled in Simulink®. Once complete the reactor and radiator components of the model were validated with experimental data. The model was then run using a highway cycle, an aggressive cycle, cold-start cycle and hot drive cycle. The system design was adjusted to meet these drive cycles. A sensitivity analysis was then performed to identify the range of material properties where these DOE targets and drive cycles could be met. Materials with a heat of reaction greater than 11 kJ/mol H2 generated and a slurry hydrogen capacity of greater than 11.4% will meet the on-board efficiency and gravimetric capacity targets, respectively.

  4. The relationship of surface roughness and cell response of chemical surface modification of titanium

    Science.gov (United States)

    Zareidoost, Amir; Ghaseme, Behrooz

    2012-01-01

    Implant surface topography influences osteoblastic proliferation, differentiation and extracellular matrix protein expressions. Previous researches proved that chemical surface modification of titanium implants could be used to improve Bone-to-implant contact. In this study, the surface topography, chemistry and biocompatibility of polished titanium surfaces treated with mixed solution of three acids containing HCl, HF and H3PO4 with different etched conditions for example concentration, time and addition of calcium chloride were studied. Osteoblast cells (MG-63) were cultured on different groups of titanium surfaces. In order to investigate titanium surfaces, SEM, AFM and EDS analyses were carried out. The results showed that surfaces treated with HCl–HF–H3PO4 had higher roughness, lower cytotoxicity level and better biocompatibility than controls. Moreover, addition of calcium chloride into mixed solution of three acids containing HCl, HF and H3PO4 is an important, predominant and new technique for obtaining biofunction in metals for biomedical use including dentistry. PMID:22460230

  5. Accelerated generation of human induced pluripotent stem cells with retroviral transduction and chemical inhibitors under physiological hypoxia

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Hidenori [Department of Bioartificial Organs, Institute for Frontier Medical Sciences, Kyoto University, 53 Kawaharacho, Shogoin, Sakyoku, Kyoto 606-8507 (Japan); Hashimoto, Yoshiya [Department of Biomaterials, Osaka Dental University, 8-1, Hanazonocho, Kuzuha, Hirakatashi, Osaka 573-1121 (Japan); Nakada, Akira; Shigeno, Keiji [Department of Bioartificial Organs, Institute for Frontier Medical Sciences, Kyoto University, 53 Kawaharacho, Shogoin, Sakyoku, Kyoto 606-8507 (Japan); Nakamura, Tatsuo, E-mail: nakamura@frontier.kyoto-u.ac.jp [Department of Bioartificial Organs, Institute for Frontier Medical Sciences, Kyoto University, 53 Kawaharacho, Shogoin, Sakyoku, Kyoto 606-8507 (Japan)

    2012-01-13

    Highlights: Black-Right-Pointing-Pointer Very rapid generation of human iPS cells under optimized conditions. Black-Right-Pointing-Pointer Five chemical inhibitors under hypoxia boosted reprogramming. Black-Right-Pointing-Pointer We performed genome-wide DNA methylation analysis. -- Abstract: Induced pluripotent stem (iPS) cells are generated from somatic cells by the forced expression of a defined set of pluripotency-associated transcription factors. Human iPS cells can be propagated indefinitely, while maintaining the capacity to differentiate into all cell types in the body except for extra-embryonic tissues. This technology not only represents a new way to use individual-specific stem cells for regenerative medicine but also constitutes a novel method to obtain large amounts of disease-specific cells for biomedical research. Despite their great potential, the long reprogramming process (up to 1 month) remains one of the most significant challenges facing standard virus-mediated methodology. In this study, we report the accelerated generation of human iPS cells from adipose-derived stem (ADS) cells, using a new combination of chemical inhibitors under a setting of physiological hypoxia in conjunction with retroviral transduction of Oct4, Sox2, Klf4, and L-Myc. Under optimized conditions, we observed human embryonic stem (ES)-like cells as early as 6 days after the initial retroviral transduction. This was followed by the emergence of fully reprogrammed cells bearing Tra-1-81-positive and DsRed transgene-silencing properties on day 10. The resulting cell lines resembled human ES cells in many respects including proliferation rate, morphology, pluripotency-associated markers, global gene expression patterns, genome-wide DNA methylation states, and the ability to differentiate into all three of the germ layers, both in vitro and in vivo. Our method, when combined with chemical inhibitors under conditions of physiological hypoxia, offers a powerful tool for rapidly

  6. Phosphonate O-deethylation of [4-(4-bromo-2-cyano-phenylcarbamoyl) benzyl]-phosphonic acid diethyl ester, a lipoprotein lipase-promoting agent, catalyzed by cytochrome P450 2C8 and 3A4 in human liver microsomes.

    Science.gov (United States)

    Morioka, Yujiro; Otsu, Makiko; Naito, Shinsaku; Imai, Teruko

    2002-03-01

    NO-1886 ([4-(4-bromo-2-cyano-phenylcarbamoyl) benzyl]-phosphonic acid diethyl ester) increases lipoprotein lipase activity, resulting in a reduction in plasma triglycerides and an increase in high-density lipoprotein cholesterol. The metabolism of NO-1886 in human liver was investigated in the present study. Ester cleavage of NO-1886 from diethyl phosphonate to monoethyl phosphonate was the major metabolic pathway catalyzed by cytochrome P450. In addition, the minor metabolic pathway in human liver was the hydrolysis of the amide bond of NO-1886 by a specific cytosolic esterase. Eadie-Hofstee plots of phosphonate O-deethylation of NO-1886 in human liver microsomes showed a biphasic curve, indicating low- and high-K(m) components. Inhibition experiments with chemical inhibitors and antibodies against various cytochrome P450 isoforms suggested the involvement of CYP2C8 and CYP3A in the phosphonate O-deethylation. Recombinant CYP3A4 and CYP2C8 expressed in baculovirus-infected insect cells and human lymphoblastoid cells exhibited a high activity for phosphonate O-deethylation of NO-1886. The recombinant cytochrome P450 enzymes indicated that CYP2C8 and CYP3A4 were responsible for the low- and high-K(m) components in human liver microsomes, respectively. The selectivity of CYP2C8 in catalyzing phosphonate O-deethylation indicates that coadministration of drugs that are metabolized by the same enzyme requires careful consideration.

  7. Cells and the environment. How do chemical pollutants affect cells. Zelle und Umwelt. Wie wirken sich Umweltgifte auf Zellen aus

    Energy Technology Data Exchange (ETDEWEB)

    Braunbeck, T.; Storch, V. (Heidelberg Univ. (Germany, F.R.). Zoologisches Inst.)

    1989-08-01

    It is possible by means of ultrastructural techniques to prove the harmful effect of chemicals on animal organisms through changes in monitoring organs such as the liver of vertebrates very early and with great sensitivity. The reaction of the fish liver to chemicals in dependence of other factors (fish species, sex) is demonstrated by the example of various model chemicals as well as two pesticides. (orig.).

  8. [Toxicity evaluation of sewage treatment plant effluent of chemical industrial park along the Yangtze River on rat testicular germ cells in vitro].

    Science.gov (United States)

    Hu, Guan-Jiu; Wang, Xiao-Yi; Shi, Wei; Bai, Chou-Yong; Wu, Jiang; Liu, Hong-Ling; Yu, Hong-Xia

    2009-05-15

    By using rat testicular germ cells in vitro toxicity testing method based on original cells culture, the reproduction toxicity of sewage treatment plant effluent of Chemical Industrial Park along the Yangtze River was evaluated, through cells changes in morphologic, activity and viability parameters. The results showed that both of the effluents from new developed Chemical Industrial Park A and provincial Chemical Industrial Park B contain reproductive toxic substances. The toxicity of Park A has more significant undergone changes in cells activity of sertoli cells (p Park B. Sepermatogenic cells are more sensitive in indicating reproduction toxicity for testicular, compared with leyding cells and sertoli cells. This study demonstrated that, as an indispensable and complementary tool for water quality assessment, rat testicular germ cells in vitro toxicity testing based on original cells culture can be used to comprehensively evaluate the reproduction toxicity of sewage treatment plant effluent, and provide prompt and useful discharge quality information.

  9. Preliminary viability studies of fibroblastic cells cultured on microcrystalline and nanocrystalline diamonds produced by chemical vapour deposition method

    Directory of Open Access Journals (Sweden)

    Ana Amélia Rodrigues

    2013-02-01

    Full Text Available Implant materials used in orthopedics surgery have demonstrated some disadvantages, such as metallic corrosion processes, generation of wear particles, inflammation reactions and bone reabsorption in the implant region. The diamond produced through hot-filament chemical vapour deposition method is a new potential biomedical material due to its chemical inertness, extreme hardness and low coefficient of friction. In the present study we analysis two samples: the microcrystalline diamond and the nanocrystalline diamond. The aim of this study was to evaluate the surface properties of the diamond samples by scanning electron microscopy, Raman spectroscopy and atomic force microscopy. Cell viability and morphology were assessed using thiazolyl blue tetrazolium bromide, cytochemical assay and scanning electron microscopy, respectively. The results revealed that the two samples did not interfere in the cell viability, however the proliferation of fibroblasts cells observed was comparatively higher with the nanocrystalline diamond.

  10. Preliminary viability studies of fibroblastic cells cultured on microcrystalline and nanocrystalline diamonds produced by chemical vapour deposition method

    Directory of Open Access Journals (Sweden)

    Ana Amélia Rodrigues

    2012-01-01

    Full Text Available Implant materials used in orthopedics surgery have demonstrated some disadvantages, such as metallic corrosion processes, generation of wear particles, inflammation reactions and bone reabsorption in the implant region. The diamond produced through hot-filament chemical vapour deposition method is a new potential biomedical material due to its chemical inertness, extreme hardness and low coefficient of friction. In the present study we analysis two samples: the microcrystalline diamond and the nanocrystalline diamond. The aim of this study was to evaluate the surface properties of the diamond samples by scanning electron microscopy, Raman spectroscopy and atomic force microscopy. Cell viability and morphology were assessed using thiazolyl blue tetrazolium bromide, cytochemical assay and scanning electron microscopy, respectively. The results revealed that the two samples did not interfere in the cell viability, however the proliferation of fibroblasts cells observed was comparatively higher with the nanocrystalline diamond.

  11. Primary cilia: the chemical antenna regulating human adipose-derived stem cell osteogenesis.

    Directory of Open Access Journals (Sweden)

    Josephine C Bodle

    Full Text Available Adipose-derived stem cells (ASC are multipotent stem cells that show great potential as a cell source for osteogenic tissue replacements and it is critical to understand the underlying mechanisms of lineage specification. Here we explore the role of primary cilia in human ASC (hASC differentiation. This study focuses on the chemosensitivity of the primary cilium and the action of its associated proteins: polycystin-1 (PC1, polycystin-2 (PC2 and intraflagellar transport protein-88 (IFT88, in hASC osteogenesis. To elucidate cilia-mediated mechanisms of hASC differentiation, siRNA knockdown of PC1, PC2 and IFT88 was performed to disrupt cilia-associated protein function. Immunostaining of the primary cilium structure indicated phenotypic-dependent changes in cilia morphology. hASC cultured in osteogenic differentiation media yielded cilia of a more elongated conformation than those cultured in expansion media, indicating cilia-sensitivity to the chemical environment and a relationship between the cilium structure and phenotypic determination. Abrogation of PC1, PC2 and IFT88 effected changes in both hASC proliferation and differentiation activity, as measured through proliferative activity, expression of osteogenic gene markers, calcium accretion and endogenous alkaline phosphatase activity. Results indicated that IFT88 may be an early mediator of the hASC differentiation process with its knockdown increasing hASC proliferation and decreasing Runx2, alkaline phosphatase and BMP-2 mRNA expression. PC1 and PC2 knockdown affected later osteogenic gene and end-product expression. PC1 knockdown resulted in downregulation of alkaline phosphatase and osteocalcin gene expression, diminished calcium accretion and reduced alkaline phosphatase enzymatic activity. Taken together our results indicate that the structure of the primary cilium is intimately associated with the process of hASC osteogenic differentiation and that its associated proteins are critical

  12. Predicting drug metabolism by cytochrome P450 2C9

    DEFF Research Database (Denmark)

    Rydberg, Patrik; Olsen, Lars

    2012-01-01

    By the use of knowledge gained through modeling of drug metabolism mediated by the cytochrome P450 2D6 and 3A4 isoforms, we constructed a 2D-based model for site-of-metabolism prediction for the cytochrome P450 2C9 isoform. The similarities and differences between the models for the 2C9 and 2D6...

  13. The SMARTCyp cytochrome P450 metabolism prediction server

    DEFF Research Database (Denmark)

    Rydberg, Patrik; Gloriam, David Erik Immanuel; Olsen, Lars

    2010-01-01

    The SMARTCyp server is the first web application for site of metabolism prediction of cytochrome P450-mediated drug metabolism.......The SMARTCyp server is the first web application for site of metabolism prediction of cytochrome P450-mediated drug metabolism....

  14. The cytotoxicity of lead and uranium on rat osteoblastic cells is highly dependent on chemical speciation and cellular accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Milgram, S.; Carriere, M.; Thiebault, C.; Gouget, B. [CEA Saclay, CNRS - UMR9956, Lab Pierre Sue, F-91198 Gif Sur Yvette, (France); Malval, L. [INSERM, E366, Lab Biol Tissue Osseux, St Etienne, (France)

    2007-07-01

    Complete text of publication follows: Uranium (U) and lead (Pb), as other heavy metals, present a strong chemical toxicity. After blood contamination, U and Pb, complexed with proteins or inorganic molecules are conveyed to target organs, the skeleton being the major long-term storage site. Once in bones, both metals are incorporated in the hydroxyapatite matrix by substitution with calcium. They can thus be released during re-modelling, which explains in part their toxicity. Although the clinical effects of these metals are well known, the cellular mechanisms of their action are not well understood. To investigate the biological effects of U and Pb acute exposure on osteoblasts, ROS17/2.8 cells were exposed to Pb or U [0-1 mM] for 24 h. The most relevant chemical and physical states, namely the most likely forms (species) of the toxics in contact with cells after blood contamination were selected for cell exposure. For each metal species, Pb and U toxicity were assessed through cell viability assay. The results show that whatever the speciation, U chemical toxicity to bone cells is far lower than Pb toxicity. Pb appears to be cytotoxic when left free in the exposure medium or when it is complexed with bicarbonate, cysteine or citrate, but not with albumin or phosphate (an insoluble form of Pb). In order to explain these differences in sensitivity between different metals and metal chemical species, time-course and dose-response curves of cellular accumulation at lethal or sub-lethal doses were drawn by direct elemental analysis of metal concentrations in digested cell pellets, using Inductive Coupling Plasma Mass Spectroscopy. These showed a clear correlation between toxicity and cellular accumulation. Also, Pb induces an inhibition of ALP activity after 24 h exposure to sub-lethal doses, which is speciation-dependent and again correlates with cellular accumulation. Phenotypic effects of U are under investigation. In addition, electron-microscopic observation of

  15. An 8.68% efficiency chemically-doped-free graphene-silicon solar cell using silver nanowires network buried contacts.

    Science.gov (United States)

    Yang, Lifei; Yu, Xuegong; Hu, Weidan; Wu, Xiaolei; Zhao, Yan; Yang, Deren

    2015-02-25

    Graphene-silicon (Gr-Si) heterojunction solar cells have been recognized as one of the most low-cost candidates in photovoltaics due to its simple fabrication process. However, the high sheet resistance of chemical vapor deposited (CVD) Gr films is still the most important limiting factor for the improvement of the power conversion efficiency of Gr-Si solar cells, especially in the case of large device-active area. In this work, we have fabricated a novel transparent conductive film by hybriding a monolayer Gr film with silver nanowires (AgNWs) network soldered by the graphene oxide (GO) flakes. This Gr-AgNWs hybrid film exhibits low sheet resistance and larger direct-current to optical conductivity ratio, quite suitable for solar cell fabrication. An efficiency of 8.68% has been achieved for the Gr-AgNWs-Si solar cell, in which the AgNWs network acts as buried contacts. Meanwhile, the Gr-AgNWs-Si solar cells have much better stability than the chemically doped Gr-Si solar cells. These results show a new route for the fabrication of high efficient and stable Gr-Si solar cells.

  16. Cloning, expression and purification of cytochrome c{sub 6} from the brown alga Hizikia fusiformis and complete X-ray diffraction analysis of the structure

    Energy Technology Data Exchange (ETDEWEB)

    Akazaki, Hideharu [Bio-organic Chemistry Laboratory, Graduate School of Bioresource Sciences, Nihon University, Kameino 1866, Fujisawa-shi, Kanagawa 252-8510 (Japan); Kawai, Fumihiro [Protein Design Laboratory, Graduate School of Integrated Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi, Yokohama 230-0045 (Japan); Chida, Hirotaka; Matsumoto, Yuichirou; Hirayama, Mao; Hoshikawa, Ken [Bio-organic Chemistry Laboratory, Graduate School of Bioresource Sciences, Nihon University, Kameino 1866, Fujisawa-shi, Kanagawa 252-8510 (Japan); Unzai, Satoru [Protein Design Laboratory, Graduate School of Integrated Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi, Yokohama 230-0045 (Japan); Hakamata, Wataru; Nishio, Toshiyuki; Park, Sam-Yong; Oku, Tadatake, E-mail: oku@brs.nihon-u.ac.jp [Bio-organic Chemistry Laboratory, Graduate School of Bioresource Sciences, Nihon University, Kameino 1866, Fujisawa-shi, Kanagawa 252-8510 (Japan)

    2008-08-01

    The crystal structure of cytochrome c{sub 6} from the brown alga H. fusiformis has been determined at 1.6 Å resolution. The amino-acid sequence and tertiary structure of H. fusiformis cytochrome c{sub 6} were very similar to those of red algal cytochrome c{sub 6} rather than those of green algal cytochrome c{sub 6}. The primary sequence of cytochrome c{sub 6} from the brown alga Hizikia fusiformis has been determined by cDNA cloning and the crystal structure has been solved at 1.6 Å resolution. The crystal belonged to the tetragonal space group P4{sub 1}2{sub 1}2, with unit-cell parameters a = b = 84.58, c = 232.91 Å and six molecules per asymmetric unit. The genome code, amino-acid sequence and crystal structure of H. fusiformis cytochrome c{sub 6} were most similar to those of red algal cytochrome c{sub 6}. These results support the hypothesis that brown algae acquired their chloroplasts via secondary endosymbiosis involving a red algal endosymbiont and a eukaryote host.

  17. Endocannabinoid release modulates electrical coupling between CCK cells connected via chemical and electrical synapses in CA1

    Directory of Open Access Journals (Sweden)

    Jonathan eIball

    2011-11-01

    Full Text Available Electrical coupling between some subclasses of interneurons is thought to promote coordinated firing that generates rhythmic synchronous activity in cortical regions. Synaptic activity of cholesystokinin (CCK interneurons which co-express cannbinoid type-1 (CB1 receptors are powerful modulators of network activity via the actions of endocannabinoids. We investigated the modulatory actions of endocannabinoids between chemically and electrically connected synapses of CCK cells using paired whole-cell recordings combined with biocytin and double immunofluorescence labelling in acute slices of rat hippocampus at P18-20 days. CA1 stratum radiatum CCK Schaffer collateral associated (SCA cells were coupled electrically with each other as well as CCK basket cells and CCK cells with axonal projections expanding to dentate gyrus. Approximately 50% of electrically coupled cells received facilitating, asynchronously released IPSPs that curtailed the steady-state coupling coefficient by 57%. Tonic CB1 receptor activity which reduces inhibition enhanced electrical coupling between cells that were connected via chemical and electrical synapses. Blocking CB1 receptors with antagonist, AM-251 (5M resulted in the synchronized release of larger IPSPs and this enhanced inhibition further reduced the steady-state coupling coefficient by 85%. Depolarization induced suppression of inhibition (DSI, maintained the asynchronicity of IPSP latency, but reduced IPSP amplitudes by 95% and enhanced the steady-state coupling coefficient by 104% and IPSP duration by 200%. However, DSI did not did not enhance electrical coupling at purely electrical synapses. These data suggest that different morphological subclasses of CCK interneurons are interconnected via gap junctions. The synergy between the chemical and electrical coupling between CCK cells probably plays a role in activity-dependent endocannabinoid modulation of rhythmic synchronization.

  18. Optimization of Albumin Secretion and Metabolic Activity of Cytochrome P450 1A1 of Human Hepatoblastoma HepG2 Cells in Multicellular Spheroids by Controlling Spheroid Size.

    Science.gov (United States)

    Nishikawa, Tomoko; Tanaka, Yutaro; Nishikawa, Makiya; Ogino, Yuka; Kusamori, Kosuke; Mizuno, Narumi; Mizukami, Yuya; Shimizu, Kazunori; Konishi, Satoshi; Takahashi, Yuki; Takakura, Yoshinobu

    2017-01-01

    Multicellular spheroids are useful as three-dimensional cell culture systems and for cell-based therapies. Their successful application requires an understanding of the consequences of spheroid size for cellular functions. In the present study, we prepared multicellular spheroids of different sizes using the human hepatoblastoma HepG2 cells, as hepatocytes are frequently used for in vitro drug screening and cell-based therapy. Precise polydimethylsiloxane-based microwells with widths of 360, 450, 560, and 770 µm were fabricated using a micromolding technique. Incubation of HepG2 cells in cell culture plates containing the microwells resulted in the formation of HepG2 spheroids with average diameters of 195, 320, 493, and 548 µm. The cell number per spheroid positively correlated with its diameter, and the viability of HepG2 cells was 94% or above for all samples. The smallest HepG2 spheroids showed the highest albumin secretion. On the other hand, the metabolic activity of 7-ethoxyresorufin, a fluorometric substrate for CYP1A1, increased with increasing spheroid size. These results indicate that controlling spheroid size is important when preparing HepG2 spheroids and that the size of HepG2 spheroids greatly influences the cellular function of HepG2 cells in the spheroids.

  19. Kinetic Monte Carlo Simulations and Molecular Conductance Measurements of the Bacterial Decaheme Cytochrome MtrF

    Energy Technology Data Exchange (ETDEWEB)

    Byun, H. S.; Pirbadian, S.; Nakano, Aiichiro; Shi, Liang; El-Naggar, Mohamed Y.

    2014-09-05

    Microorganisms overcome the considerable hurdle of respiring extracellular solid substrates by deploying large multiheme cytochrome complexes that form 20 nanometer conduits to traffic electrons through the periplasm and across the cellular outer membrane. Here we report the first kinetic Monte Carlo simulations and single-molecule scanning tunneling microscopy (STM) measurements of the Shewanella oneidensis MR-1 outer membrane decaheme cytochrome MtrF, which can perform the final electron transfer step from cells to minerals and microbial fuel cell anodes. We find that the calculated electron transport rate through MtrF is consistent with previously reported in vitro measurements of the Shewanella Mtr complex, as well as in vivo respiration rates on electrode surfaces assuming a reasonable (experimentally verified) coverage of cytochromes on the cell surface. The simulations also reveal a rich phase diagram in the overall electron occupation density of the hemes as a function of electron injection and ejection rates. Single molecule tunneling spectroscopy confirms MtrF's ability to mediate electron transport between an STM tip and an underlying Au(111) surface, but at rates higher than expected from previously calculated heme-heme electron transfer rates for solvated molecules.

  20. Liver microsomal cytochromes P-450 and azoreductase activity.

    Science.gov (United States)

    Fujita, S; Peisach, J

    1978-07-10

    Hepatic microsomal azoreductase activity with amaranth (3-hydroxy-4[(4-sulfo-1-naphthalenyl)azo]-2,7-naphthalenedisulfonic acid trisodium salt) as a substrate is proportional to the levels of microsomal cytochrome P-450 from control or phenobarbital-pretreated rats and mice or cytochrome P-448 from 3-methylchol-anthrene-pretreated animals. In the "inducible" C57B/6J strain of mice, 3-methylcholanthrene and phenobarbital pretreatment cause an increase in cytochrome P-448 and P-450 levels, respectively, which is directly proportional to the increase of azoreductase activity. However, in the "noninducible" DBA/2J strain of mice, only phenobarbital treatment causes the increase both in cytochrome P-450 levels and azoreductase activity, while 3-methylcholanthrene has no effect. These experiments suggest that the P-450 type cytochromes are responsible for azoreductase activity in liver microsomes.

  1. The caspase-8/Bid/cytochrome c axis links signals from death receptors to mitochondrial reactive oxygen species production.

    Science.gov (United States)

    Kim, Wan-Sung; Lee, Kwang-Soon; Kim, Ji-Hee; Kim, Chun-Ki; Lee, Gwangsoo; Choe, Jongseon; Won, Moo-Ho; Kim, Tae-Hyoung; Jeoung, Dooil; Lee, Hansoo; Kim, Ji-Yoon; Ae Jeong, Mi; Ha, Kwon-Soo; Kwon, Young-Guen; Kim, Young-Myeong

    2017-11-01

    Ligation of the death receptors for TNF-α, FasL, and TRAIL triggers two common pathways, caspase-dependent intrinsic apoptosis and intracellular reactive oxygen species (ROS) generation. The apoptotic pathway is well characterized; however, a signaling linker between the death receptor and ROS production has not been clearly elucidated. Here, we found that death receptor-induced ROS generation was strongly inhibited by mitochondrial complex I and II inhibitors, but not by inhibitors of NADPH oxidase, lipoxygenase, cyclooxygenase or xanthine oxidase, indicating that ROS are mostly generated by the impairment of the mitochondrial respiratory chain. ROS generation was accompanied by caspase-8 activation, Bid cleavage, and cytochrome c release; it was blocked in FADD- and caspase-8-deficient cells, as well as by caspase-8 knockdown and inhibitor. Moreover, Bid knockdown abrogated TNF-α- or TRAIL-induced ROS generation, whereas overexpression of truncated Bid (tBid) or knockdown of cytochrome c spontaneously elevated ROS production. In addition, p53-overexpressing cells accumulated intracellular ROS via cytochrome c release mediated by the BH3-only protein Noxa induction. In a cell-free reconstitution system, caspase-8-mediated Bid cleavage and recombinant tBid induced mitochondrial cytochrome c release and ROS generation, which were blocked by Bcl-xL and antioxidant enzymes. These data suggest that anti-apoptotic Bcl-2 proteins play an important role in mitochondrial ROS generation by preventing cytochrome c release. These data provide evidence that the FADD/caspase-8/Bid/cytochrome c axis is a crucial linker between death receptors and mitochondria, where they play a role in ROS generation and apoptosis. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Effects of Pluronic F-68 on Tetrahymena cells: protection against chemical and physical stress and prolongation of survival under toxic conditions

    DEFF Research Database (Denmark)

    Hellung-Larsen, P; Assaad, F; Pankratova, Stanislava

    2000-01-01

    The effects of the non-ionic surfactant Pluronic F-68 (0.01% w/v) on Tetrahymena cells have been studied. A marked protection against chemical and physical stress was observed. The chemical stress effects were studied in cells suspended in buffer (starvation) or in buffers with added ingredients ...

  3. Chemical and Structural Differences in Cell Wall Polysaccharides of Two Monokaryotic Strains and Their Resulting Dikaryon of Agaricus bisporus

    Science.gov (United States)

    Garcia Mendoza C; Perez Cabo A; Calonje; Galan; Novaes-Ledieu

    1996-10-01

    Compatible monokaryotic strains of Agaricus bisporus ATCC 36975 and 36976 and the resulting dikaryon of their mating were grown in a liquid medium, and their respective cell walls were prepared. Significant differences were not found in the gross chemical composition of the three hyphal types. However, the neutral carbohydrate composition of the complete walls and their fractions was found to be somewhat different in each strain. More consistent differences were encountered in the chemical structure of the distinct polysaccharidic wall fractions in the three types of organisms. Some of these structural wall differences can be considered as characteristic markers for differentiating the mono- and dikaryotic types of A. bisporus.

  4. The influence of plasma technology coupled to chemical grafting on the cell growth compliance of 3D hydroxyapatite scaffolds.

    Science.gov (United States)

    Russo, Laura; Zanini, Stefano; Giannoni, Paolo; Landi, Elena; Villa, Anna; Sandri, Monica; Riccardi, Claudia; Quarto, Rodolfo; Doglia, Silvia M; Nicotra, Francesco; Cipolla, Laura

    2012-11-01

    The development of advanced materials with biomimetic features in order to elicit desired biological responses and to guarantee tissue biocompatibility is recently gaining attention for tissue engineering applications. Bioceramics, such as hydroxyapatite-based biomaterials are now used in a number of different applications throughout the body, covering all areas of the skeleton, due to their biological and chemical similarity to the inorganic phases of bones. When bioactive sintered hydroxyapatite (HA) is desired, biomolecular modification of these materials is needed. In the present work, we investigated the influence of plasma surface modification coupled to chemical grafting on the cell growth compliance of HA 3D scaffolds.

  5. Chemical resolution of Pu+ from U+ and Am+ using a band-pass reaction cell inductively coupled plasma mass spectrometer.

    Science.gov (United States)

    Tanner, Scott D; Li, Chunsheng; Vais, Vladimir; Baranov, Vladimir I; Bandura, Dmitry R

    2004-06-01

    Determination of the concentration and distribution of the Pu and Am isotopes is hindered by the isobaric overlaps between the elements themselves and U, generally requiring time-consuming chemical separation of the elements. A method is described in which chemical resolution of the elemental ions is obtained through ion-molecule reactions in a reaction cell of an ICPMS instrument. The reactions of "natural" U(+), (242)Pu(+), and (243)Am(+) with ethylene, carbon dioxide, and nitric oxide are reported. Since the net sensitivities to the isotopes of an element are similar, chemical resolution is inferred when one isobaric element reacts rapidly with a given gas and the isobar (or in this instance surrogate isotope) is unreactive or slowly reactive. Chemical resolution of the m/z 238 isotopes of U and Pu can be obtained using ethylene as a reaction gas, but little improvement in the resolution of the m/z 239 isobars is obtained. However, high efficiency of reaction of U(+) and UH(+) with CO(2), and nonreaction of Pu(+), allows the sub-ppt determination of (239)Pu, (240)Pu, and (242)Pu (single ppt for (238)Pu) in the presence of 7 orders of magnitude excess U matrix without prior chemical separation. Similarly, oxidation of Pu(+) by NO, and nonreaction of Am(+), permit chemical resolution of the isobars of Pu and Am over 2-3 orders of magnitude relative concentration. The method provides the potential for analysis of the actinides with reduced sample matrix separation.

  6. Synthetic surface for expansion of human mesenchymal stem cells in xeno-free, chemically defined culture conditions.

    Directory of Open Access Journals (Sweden)

    Paula J Dolley-Sonneville

    Full Text Available Human mesenchymal stem cells (HMSCS possess three properties of great interest for the development of cell therapies and tissue engineering: multilineage differentiation, immunomodulation, and production of trophic factors. Efficient ex vivo expansion of hMSCs is a challenging requirement for large scale production of clinical grade cells. Low-cost, robust, scalable culture methods using chemically defined materials need to be developed to address this need. This study describes the use of a xeno-free synthetic peptide acrylate surface, the Corning® Synthemax® Surface, for culture of hMSCs in serum-free, defined medium. Cell performance on the Corning Synthemax Surface was compared to cells cultured on biological extracellular matrix (ECM coatings in xeno-free defined medium and in traditional conditions on tissue culture treated (TCT plastic in fetal bovine serum (FBS supplemented medium. Our results show successful maintenance of hMSCs on Corning Synthemax Surface for eight passages, with cell expansion rate comparable to cells cultured on ECM and significantly higher than for cells in TCT/FBS condition. Importantly, on the Corning Synthemax Surface, cells maintained elongated, spindle-like morphology, typical hMSC marker profile and in vitro multilineage differentiation potential. We believe the Corning Synthemax Surface, in combination with defined media, provides a complete synthetic, xeno-free, cell culture system for scalable production of hMSCs.

  7. Evaluation of cell behaviour related to physico-chemical properties of polymeric membranes to be used in bioartificial organs.

    Science.gov (United States)

    De Bartolo, Loredana; Morelli, Sabrina; Bader, Augustinus; Drioli, Enrico

    2002-06-01

    In bioartificial organs using isolated cells, polymeric semipermeable membranes are used as immunoselective barriers as a means for cell oxygenation and also as substrata for adhesion of anchorage-dependent cells. The capacity of the membrane to perform its functions and to provide a cytocompatible support for cell culture depends in particular on its surface properties. In this study we investigated the physico-chemical aspects of the interaction between the membrane and mammalian cells in order to provide guidelines to the selection of cytocompatible membranes. We evaluated the adhesion and metabolic behaviour of isolated liver cells cultured on various polymeric membranes such as those modified by protein adsorption. The physico-chemical properties of the membranes were characterised by contact angle measurements. The different parameters such as acid (gamma+), base (gamma-) and Lifshitz-van der Waals (gammaLW) of the surface free energy were calculated according to Good-van Oss's model. The adsorption of protein modified markedly both contact angle and components of membrane surface tension. In particular, base parameter of surface tension decreased drastically with increased water contact angle. For each investigated membrane we observed that cell adhesion increased with increasing base parameter of membrane surface tension. The absolute value of cell adhesion is higher in the presence of serum proteins adsorbed on the membrane surface, which change the wettability by increasing the base parameter of surface tension. Also, the metabolic functions improve on hydrophilic membranes. Liver cells synthesised urea with a rate that increased with increasing base parameter value of membrane surface tension. The metabolic activity is particularly expressed at high levels when cells were cultured on polycarbonate and cellulose acetate membranes.

  8. Oxidation of hydroxylamine by cytochrome P-460 of the obligate methylotroph Methylococcus capsulatus Bath.

    Science.gov (United States)

    Zahn, J A; Duncan, C; DiSpirito, A A

    1994-10-01

    An enzyme capable of the oxidation of hydroxylamine to nitrite was isolated from the obligate methylotroph Methylococcus capsulatus Bath. The absorption spectra in cell extracts, electron paramagnetic resonance spectra, molecular weight, covalent attachment of heme group to polypeptide, and enzymatic activities suggest that the enzyme is similar to cytochrome P-460, a novel iron-containing protein previously observed only in Nitrosomonas europaea. The native and subunit molecular masses of the M. capsulatus Bath protein were 38,900 and 16,390 Da, respectively; the isoelectric point was 6.98. The enzyme has approximately one iron and one copper atom per subunit. The electron paramagnetic resonance spectrum of the protein showed evidence for a high-spin ferric heme. In contrast to the enzyme from N. europaea, a 13-nm blue shift in the soret band of the ferrocytochrome (463 nm in cell extracts to 450 nm in the final sample) occurred during purification. The amino acid composition and N-terminal amino acid sequence of the enzyme from M. capsulatus Bath was similar but not identical to those of cytochrome P-460 of N. europaea. In cell extracts, the identity of the biological electron acceptor is as yet unestablished. Cytochrome c-555 is able to accept electrons from cytochrome P-460, although the purified enzyme required phenazine methosulfate for maximum hydroxylamine oxidation activity (specific activity, 366 mol of O2 per s per mol of enzyme). Hydroxylamine oxidation rates were stimulated approximately 2-fold by 1 mM cyanide and 1.5-fold by 0.1 mM 8-hydroxyquinoline.

  9. Production of a highly active, soluble form of the cytochrome P450 reductase (CPR A) from Candida tropicalis

    Science.gov (United States)

    Donnelly, Mark

    2006-08-01

    The present invention provides soluble cytochrome p450 reductase (CPR) proteins from Candida sp. having an altered N-terminal region which results in reduced hydrophobicity of the N-terminal region. Also provided are host cells comprising the subject soluble CPR proteins. In addition, the present invention provides nucleotide and corresponding amino acid sequences for soluble CPR proteins and vectors comprising the nucleotide sequences. Methods for producing a soluble CPR, for increasing production of a dicarboxylic acid, and for detecting a cytochrome P450 are also provided.

  10. Immobilized cytochrome c bound to cardiolipin exhibits peculiar oxidation state-dependent axial heme ligation and catalytically reduces dioxygen

    NARCIS (Netherlands)

    Ranieri, A.; Millo, D.; di Rocco, G.; Battistuzzi, G.; Bortolotti, C.A.; Borsari, M.; Sofa, M.

    2014-01-01

    Mitochondrial cytochrome c (cytc) plays an important role in programmed cell death upon binding to cardiolipin (CL), a negatively charged phospholipid of the inner mitochondrial membrane (IMM). Although this binding has been thoroughly investigated in solution, little is known on the nature and

  11. Comparison of brain mitochondrial cytochrome c oxidase activity with cyanide LD(50) yields insight into the efficacy of prophylactics.

    Science.gov (United States)

    Marziaz, Mandy L; Frazier, Kathryn; Guidry, Paul B; Ruiz, Robyn A; Petrikovics, Ilona; Haines, Donovan C

    2013-01-01

    Cyanide inhibits cytochrome c oxidase, the terminal oxidase of the mitochondrial respiratory pathway, therefore inhibiting the cell oxygen utilization and resulting in the condition of histotoxic anoxia. The enzyme rhodanese detoxifies cyanide by utilizing sulfur donors to convert cyanide to thiocyanate, and new and improved sulfur donors are actively sought as researchers seek to improve cyanide prophylactics. We have determined brain cytochrome c oxidase activity as a marker for cyanide exposure for mice pre-treated with various cyanide poisoning prophylactics, including sulfur donors thiosulfate (TS) and thiotaurine (TT3). Brain mitochondria were isolated by differential centrifugation, the outer mitochondrial membrane was disrupted by a maltoside detergent, and the decrease in absorbance at 550 nm as horse heart ferrocytochrome c (generated by the dithiothreitol reduction of ferricytochrome c) was oxidized was monitored. Overall, the TS control prophylactic treatment provided significant protection of the cytochrome c oxidase activity. The TT3-treated mice showed reduced cytochrome c oxidase activity even in the absence of cyanide. In both treatment series, addition of exogenous Rh did not significantly enhance the prevention of cytochrome c oxidase inhibition, but the addition of sodium nitrite did. These findings can lead to a better understanding of the protection mechanism by various cyanide antidotal systems. Copyright © 2011 John Wiley & Sons, Ltd.

  12. Analysis of Protein–Protein Interactions in MCF-7 and MDA-MB-231 Cell Lines Using Phthalic Acid Chemical

    Directory of Open Access Journals (Sweden)

    Shih-Shin Liang

    2014-11-01

    Full Text Available Phthalates are a class of plasticizers that have been characterized as endocrine disrupters, and are associated with genital diseases, cardiotoxicity, hepatotoxicity, and nephrotoxicity in the GeneOntology gene/protein database. In this study, we synthesized phthalic acid chemical probes and demonstrated differing protein–protein interactions between MCF-7 cells and MDA-MB-231 breast cancer cell lines. Phthalic acid chemical probes were synthesized using silicon dioxide particle carriers, which were modified using the silanized linker 3-aminopropyl triethoxyslane (APTES. Incubation with cell lysates from breast cancer cell lines revealed interactions between phthalic acid and cellular proteins in MCF-7 and MDA-MB-231 cells. Subsequent proteomics analyses indicated 22 phthalic acid-binding proteins in both cell types, including heat shock cognate 71-kDa protein, ATP synthase subunit beta, and heat shock protein HSP 90-beta. In addition, 21 MCF-7-specific and 32 MDA-MB-231 specific phthalic acid-binding proteins were identified, including related proteasome proteins, heat shock 70-kDa protein, and NADPH dehydrogenase and ribosomal correlated proteins, ras-related proteins, and members of the heat shock protein family, respectively.

  13. Defense Waste Processing Facility Simulant Chemical Processing Cell Studies for Sludge Batch 9

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Tara E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Newell, J. David [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Woodham, Wesley H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-08-10

    The Savannah River National Laboratory (SRNL) received a technical task request from Defense Waste Processing Facility (DWPF) and Saltstone Engineering to perform simulant tests to support the qualification of Sludge Batch 9 (SB9) and to develop the flowsheet for SB9 in the DWPF. These efforts pertained to the DWPF Chemical Process Cell (CPC). CPC experiments were performed using SB9 simulant (SB9A) to qualify SB9 for sludge-only and coupled processing using the nitric-formic flowsheet in the DWPF. Two simulant batches were prepared, one representing SB8 Tank 40H and another representing SB9 Tank 51H. The simulant used for SB9 qualification testing was prepared by blending the SB8 Tank 40H and SB9 Tank 51H simulants. The blended simulant is referred to as SB9A. Eleven CPC experiments were run with an acid stoichiometry ranging between 105% and 145% of the Koopman minimum acid equation (KMA), which is equivalent to 109.7% and 151.5% of the Hsu minimum acid factor. Three runs were performed in the 1L laboratory scale setup, whereas the remainder were in the 4L laboratory scale setup. Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) cycles were performed on nine of the eleven. The other two were SRAT cycles only. One coupled flowsheet and one extended run were performed for SRAT and SME processing. Samples of the condensate, sludge, and off-gas were taken to monitor the chemistry of the CPC experiments.

  14. FY13 GLYCOLIC-NITRIC ACID FLOWSHEET DEMONSTRATIONS OF THE DWPF CHEMICAL PROCESS CELL WITH SIMULANTS

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D.; Zamecnik, J.; Best, D.

    2014-03-13

    Savannah River Remediation is evaluating changes to its current Defense Waste Processing Facility flowsheet to replace formic acid with glycolic acid in order to improve processing cycle times and decrease by approximately 100x the production of hydrogen, a potentially flammable gas. Higher throughput is needed in the Chemical Processing Cell since the installation of the bubblers into the melter has increased melt rate. Due to the significant maintenance required for the safety significant gas chromatographs and the potential for production of flammable quantities of hydrogen, eliminating the use of formic acid is highly desirable. Previous testing at the Savannah River National Laboratory has shown that replacing formic acid with glycolic acid allows the reduction and removal of mercury without significant catalytic hydrogen generation. Five back-to-back Sludge Receipt and Adjustment Tank (SRAT) cycles and four back-to-back Slurry Mix Evaporator (SME) cycles were successful in demonstrating the viability of the nitric/glycolic acid flowsheet. The testing was completed in FY13 to determine the impact of process heels (approximately 25% of the material is left behind after transfers). In addition, back-to-back experiments might identify longer-term processing problems. The testing was designed to be prototypic by including sludge simulant, Actinide Removal Product simulant, nitric acid, glycolic acid, and Strip Effluent simulant containing Next Generation Solvent in the SRAT processing and SRAT product simulant, decontamination frit slurry, and process frit slurry in the SME processing. A heel was produced in the first cycle and each subsequent cycle utilized the remaining heel from the previous cycle. Lower SRAT purges were utilized due to the low hydrogen generation. Design basis addition rates and boilup rates were used so the processing time was shorter than current processing rates.

  15. Immobilization of cytochrome c and its application as electrochemical biosensors.

    Science.gov (United States)

    Aghamiri, Zahra Sadat; Mohsennia, Mohsen; Rafiee-Pour, Hossain-Ali

    2018-01-01

    Cytochrome c (Cyt c) has been used as a model protein to investigate the characters of modified electrodes by many researchers. It has been also employed to construct biosensors to detect hydrogen peroxide, nitrate, superoxide, and etc. Cyt c immobilization techniques, including physical adsorption, entrapment in hydrogel or polymers, layer-by-layer assembly, Langmuir-Blodgett, and covalent attachment are discussed followed by various electrochemical methods applied in the electrode modification. The exploration of some modified protein electrodes, for example, screen printed, microperoxidase and engineered Cyt c are also presented. The preparation, characterizations and some properties of nanocomposites to modify electrode surface for immobilizing Cyt c are highlighted. This review is attempted to discuss the influences of the physical and chemical properties of the substrate materials, such as specific area and surface charge on the protein loading and electron transfer of Cyt c briefly. The comparative information of Cyt c-based electrochemical modified electrodes, such as average surface coverage, sensitivity, linear range, and detection limit of the analyte of interest is also summarized. Copyright © 2017. Published by Elsevier B.V.

  16. Phenobarbital-induced expression of cytochrome P450 genes.

    Science.gov (United States)

    Czekaj, P

    2000-01-01

    In contrast to the well-known Ah receptor-mediated regulation of the CYP1A1 gene by polycyclic aromatic hydrocarbons, the molecular mechanism by which phenobarbital (PB) and PB-like inducers affect transcription of CYP genes remains unknown; no receptor for these chemicals has been found to date. However, in the last 5 years PB-responsive sequences have been identified in the 5' flanking regions of several P450 genes. The phenobarbital-responsive enhancer unit (PBRU) of CYP2B gene family members contain two potential nuclear receptor binding sites (NR1 and NR2) that flank a nuclear factor 1 (NF-1) binding motif. The nuclear factors that regulate PBRU activity have not yet been characterized. It seems that PB may activate multiple nuclear orphan receptors to induce various CYP genes. CYP2B and CYP3A genes appear to be targets for the orphan receptors CAR and PXR, respectively. It is also possible that the pleiotropic effects of PB can, in part, be explained by the ability of the CAR-RXR heterodimer to bind to a variety of nuclear receptor binding motifs. The induction of cytochromes P450 may result in interactions between xenobiotics and in the interference of xenobiotic metabolism and endogenous signalling pathways.

  17. Proton-pumping mechanism of cytochrome c oxidase: A kinetic master-equation approach

    Science.gov (United States)

    Kim, Young C.; Hummer, Gerhard

    2011-01-01

    Cytochrome c oxidase (CcO) is an efficient energy transducer that reduces oxygen to water and converts the released chemical energy into an electrochemical membrane potential. As a true proton pump, CcO translocates protons across the membrane against this potential. Based on a wealth of experiments and calculations, an increasingly detailed picture of the reaction intermediates in the redox cycle has emerged. However, the fundamental mechanism of proton pumping coupled to redox chemistry remains largely unresolved. Here we examine and extend a kinetic master-equation approach to gain insight into redox-coupled proton pumping in CcO. Basic principles of the CcO proton pump emerge from an analysis of the simplest kinetic models that retain essential elements of the experimentally determined structure, energetics, and kinetics, and that satisfy fundamental physical principles. The master-equation models allow us to address the question of how pumping can be achieved in a system in which all reaction steps are reversible. Whereas proton pumping does not require the direct modulation of microscopic reaction barriers, such kinetic gating greatly increases the pumping efficiency. Further efficiency gains can be achieved by partially decoupling the proton uptake pathway from the ative-site region. Such a mechanism is consistent with the proposed Glu valve, in which the side chain of a key glutamic acid shuttles between the D channel and the active-site region. We also show that the models predict only small proton leaks even in the absence of turnover. The design principles identified here for CcO provide a blueprint for novel biology-inspired fuel cells, and the master-equation formulation should prove useful also for other molecular machines. PMID:21946020

  18. Flower colour and cytochromes P450.

    Science.gov (United States)

    Tanaka, Yoshikazu; Brugliera, Filippa

    2013-02-19

    Cytochromes P450 play important roles in biosynthesis of flavonoids and their coloured class of compounds, anthocyanins, both of which are major floral pigments. The number of hydroxyl groups on the B-ring of anthocyanidins (the chromophores and precursors of anthocyanins) impact the anthocyanin colour, the more the bluer. The hydroxylation pattern is determined by two cytochromes P450, flavonoid 3'-hydroxylase (F3'H) and flavonoid 3',5'-hydroxylase (F3'5'H) and thus they play a crucial role in the determination of flower colour. F3'H and F3'5'H mostly belong to CYP75B and CYP75A, respectively, except for the F3'5'Hs in Compositae that were derived from gene duplication of CYP75B and neofunctionalization. Roses and carnations lack blue/violet flower colours owing to the deficiency of F3'5'H and therefore lack the B-ring-trihydroxylated anthocyanins based upon delphinidin. Successful redirection of the anthocyanin biosynthesis pathway to delphinidin was achieved by expressing F3'5'H coding regions resulting in carnations and roses with novel blue hues that have been commercialized. Suppression of F3'5'H and F3'H in delphinidin-producing plants reduced the number of hydroxyl groups on the anthocyanidin B-ring resulting in the production of monohydroxylated anthocyanins based on pelargonidin with a shift in flower colour to orange/red. Pelargonidin biosynthesis is enhanced by additional expression of a dihydroflavonol 4-reductase that can use the monohydroxylated dihydrokaempferol (the pelargonidin precursor). Flavone synthase II (FNSII)-catalysing flavone biosynthesis from flavanones is also a P450 (CYP93B) and contributes to flower colour, because flavones act as co-pigments to anthocyanins and can cause blueing and darkening of colour. However, transgenic plants expression of a FNSII gene yielded paler flowers owing to a reduction of anthocyanins because flavanones are precursors of anthocyanins and flavones.

  19. Evolution of the couple cytochrome c and cytochrome c oxidase in Primates

    Science.gov (United States)

    Pierron, Denis; Wildman, Derek E.; Hüttemann, Maik; Letellier, Thierry; Grossman, Lawrence I.

    2013-01-01

    Mitochondrial energy metabolism has been affected by a broad set of ancient and recent evolutionary events. The oldest example is the endosymbiosis theory that led to mitochondria and a recently proposed example is adaptation to cold climate by anatomically modern human lineages. Mitochondrial energy metabolism has also been associated with an important area in anthropology and evolutionary biology, brain enlargement in human evolution. Indeed, several studies have pointed to the need for a major metabolic rearrangement to supply a sufficient amount of energy for brain development in primates. The gene encoding for the coupled cytochrome c (cyt c) / cytochrome c oxidase (COX, complex IV, EC 1.9.3.1) seems to have an exceptional pattern of evolution in the anthropoid lineage. It has been proposed that this evolution was linked to the rearrangement of energy metabolism needed for brain enlargement. This hypothesis is reinforced by the fact that the COX enzyme was proposed to have a large role in control of the respiratory chain and thereby global energy production. After summarizing major events that occurred during the evolution of COX and cytochrome c on the primate lineage, we review the different evolutionary forces that could have influenced primate COX evolution and discuss the probable causes and consequence of this evolution. Finally, we discuss and review the co-occurring primate phenotypic evolution. PMID:22729859

  20. A versatile chemical conversion synthesis of Cu2S nanotubes and the photovoltaic activities for dye-sensitized solar cell

    Science.gov (United States)

    2014-01-01

    A versatile, low-temperature, and low-cost chemical conversion synthesis has been developed to prepare copper sulfide (Cu2S) nanotubes. The successful chemical conversion from ZnS nanotubes to Cu2S ones profits by the large difference in solubility between ZnS and Cu2S. The morphology, structure, and composition of the yielded products have been examined by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction measurements. We have further successfully employed the obtained Cu2S nanotubes as counter electrodes in dye-sensitized solar cells. The light-to-electricity conversion results show that the Cu2S nanostructures exhibit high photovoltaic conversion efficiency due to the increased surface area and the good electrocatalytical activity of Cu2S. The present chemical route provides a simple way to synthesize Cu2S nanotubes with a high surface area for nanodevice applications. PMID:25246878

  1. Surface chemical modification of poly(dimethylsiloxane) for the enhanced adhesion and proliferation of mesenchymal stem cells.

    Science.gov (United States)

    Kuddannaya, Shreyas; Chuah, Yon Jin; Lee, Min Hui Adeline; Menon, Nishanth V; Kang, Yuejun; Zhang, Yilei

    2013-10-09

    The surface chemistry of materials has an interactive influence on cell behavior. The optimal adhesion of mammalian cells is critical in determining the cell viability and proliferation on substrate surfaces. Because of the inherent high hydrophobicity of a poly(dimethylsiloxane) (PDMS) surface, cell culture on these surfaces is unfavorable, causing cells to eventually dislodge from the surface. Although physically adsorbed matrix proteins can promote initial cell adhesion, this effect is usually short-lived. Here, (3-aminopropyl)triethoxy silane (APTES) and cross-linker glutaraldehyde (GA) chemistry was employed to immobilize either fibronectin (FN) or collagen type 1 (C1) on PDMS. The efficiency of these surfaces to support the adhesion and viability of mesenchymal stem cells (MSCs) was analyzed. The hydrophobicity of the native PDMS decreased significantly with the mentioned surface functionalization. The adhesion of MSCs was mostly favorable on chemically modified PDMS surfaces with APTES + GA + protein. Additionally, the spreading area of MSCs was significantly higher on APTES + GA + C1 surfaces than on other unmodified/modified PDMS surfaces with C1 adsorption. However, there were no significant differences in the MSC spreading area on the unmodified/modified PDMS surfaces with FN adsorption. Furthermore, there was a significant increase in cell proliferation on the PDMS surface with APTES + GA + protein functionalization as compared to the PDMS surface with protein adsorption only. Therefore, the covalent surface chemical modification of PDMS with APTES + GA + protein could offer a more biocompatible platform for the enhanced adhesion and proliferation of MSCs. Similar strategies can be applied for other substrates and cell lines by appropriate combinations of self-assembly monolayers (SAMs) and extracellular matrix proteins.

  2. Micropower chemical fuel-to-electric conversion : a "regenerative flip" hydrogen concentration cell promising near carnot efficiency.

    Energy Technology Data Exchange (ETDEWEB)

    Wally, Karl

    2006-05-01

    Although battery technology is relatively mature, power sources continue to impose serious limitations for small, portable, mobile, or remote applications. A potentially attractive alternative to batteries is chemical fuel-to-electric conversion. Chemical fuels have volumetric energy densities 4 to 10 times those of batteries. However, realizing this advantage requires efficient chemical fuel-to-electric conversion. Direct electrochemical conversion would be the ideal, but, for most fuels, is generally not within the state-of-the-science. Next best, chemical-to-thermal-to-electric conversion can be attractive if efficiencies can be kept high. This small investigative project was an exploration into the feasibility of a novel hybrid (i.e., thermal-electrochemical) micropower converter of high theoretical performance whose demonstration was thought to be within near-term reach. The system is comprised of a hydrogen concentration electrochemical cell with physically identical hydrogen electrodes as anode and cathode, with each electrode connected to physically identical hydride beds each containing the same low-enthalpy-of-formation metal hydride. In operation, electrical power is generated by a hydrogen concentration differential across the electrochemical cell. This differential is established via coordinated heating and passive cooling of the corresponding hydride source and sink. Heating is provided by the exothermic combustion (i.e., either flame combustion or catalytic combustion) of a chemical fuel. Upon hydride source depletion, the role of source and sink are reversed, heating and cooling reversed, electrodes commutatively reversed, cell operation reversed, while power delivery continues unchanged. This 'regenerative flip' of source and sink hydride beds can be cycled continuously until all available heating fuel is consumed. Electricity is efficiently generated electrochemically, but hydrogen is not consumed, rather the hydrogen is regeneratively

  3. The chemical and physical characteristics of single-walled carbon nanotube film impact on osteoblastic cell response.

    Science.gov (United States)

    Tutak, Wojtek; Chhowalla, Manish; Sesti, Federico

    2010-08-06

    Carbon-nanotube-based substrates have been shown to support the growth of different cell types and, as such, have raised considerable interest in view of their possible use in biomedical applications. Nanotube matrices are embedded in polymers which cause inherent changes in nanotube chemical and physical film properties. Thus, it is critical to understand how the physical properties of the film affect the biology of the host tissue. Here, we investigated how the physical and chemical properties of single-walled carbon nanotubes (SWNT) films impact the response of MC3T3-E1 bone osteoblasts. We found that two fundamental steps in cell growth-initial attachment to the substrate and proliferation-are strongly dependent on, respectively, the energy and roughness of the surface. Thus, fine-tuning the properties of the film may represent a valid strategy to optimize the response of the biological host.

  4. Low-Temperature, Chemically Grown Titanium Oxide Thin Films with a High Hole Tunneling Rate for Si Solar Cells

    Directory of Open Access Journals (Sweden)

    Yu-Tsu Lee

    2016-05-01

    Full Text Available In this paper, we propose a chemically grown titanium oxide (TiO2 on Si to form a heterojunction for photovoltaic devices. The chemically grown TiO2 does not block hole transport. Ultraviolet photoemission spectroscopy was used to study the band alignment. A substantial band offset at the TiO2/Si interface was observed. X-ray photoemission spectroscopy (XPS revealed that the chemically grown TiO2 is oxygen-deficient and contains numerous gap states. A multiple-trap-assisted tunneling (TAT model was used to explain the high hole injection rate. According to this model, the tunneling rate can be 105 orders of magnitude higher for holes passing through TiO2 than for flow through SiO2. With 24-nm-thick TiO2, a Si solar cell achieves a 33.2 mA/cm2 photocurrent on a planar substrate, with a 9.4% power conversion efficiency. Plan-view scanning electron microscopy images indicate that a moth-eye-like structure formed during TiO2 deposition. This structure enables light harvesting for a high photocurrent. The high photocurrent and ease of production of chemically grown TiO2 imply that it is a suitable candidate for future low-cost, high-efficiency solar cell applications.

  5. Intestinal cytochromes P450 regulating the intestinal microbiota and its probiotic profile

    Directory of Open Access Journals (Sweden)

    Eugenia Elefterios Venizelos Bezirtzoglou

    2012-09-01

    Full Text Available Cytochromes P450 (CYPs enzymes metabolize a large variety of xenobiotic substances. In this vein, a plethora of studies were conducted to investigate their role, as cytochromes are located in both liver and intestinal tissues. The P450 profile of the human intestine has not been fully characterized. Human intestine serves primarily as an absorptive organ for nutrients, although it has also the ability to metabolize drugs. CYPs are responsible for the majority of phase I drug metabolism reactions. CYP3A represents the major intestinal CYP (80% followed by CYP2C9. CYP1A is expressed at high level in the duodenum, together with less abundant levels of CYP2C8-10 and CYP2D6. Cytochromes present a genetic polymorphism intra- or interindividual and intra- or interethnic. Changes in the pharmacokinetic profile of the drug are associated with increased toxicity due to reduced metabolism, altered efficacy of the drug, increased production of toxic metabolites, and adverse drug interaction. The high metabolic capacity of the intestinal flora is due to its enormous pool of enzymes, which catalyzes reactions in phase I and phase II drug metabolism. Compromised intestinal barrier conditions, when rupture of the intestinal integrity occurs, could increase passive paracellular absorption. It is clear that high microbial intestinal charge following intestinal disturbances, ageing, environment, or food-associated ailments leads to the microbial metabolism of a drug before absorption. The effect of certain bacteria having a benefic action on the intestinal ecosystem has been largely discussed during the past few years by many authors. The aim of the probiotic approach is to repair the deficiencies in the gut flora and establish a protective effect. There is a tentative multifactorial association of the CYP (P450 cytochrome role in the different diseases states, environmental toxic effects or chemical exposures and nutritional status.

  6. Cytochromes c of Nitrobacter winogradskyi and Thiobacillus novellus: structure, function and evolution.

    Science.gov (United States)

    Yamanaka, T; Nagano, T; Shoji, K; Fukumori, Y

    1991-05-23

    The amino acid sequences of Thiobacillus novellus and Nitrobacter winogradskyi cytochromes c have been compared with those of cytochromes c from several other organisms. The two bacterial cytochromes resemble eukaryotic cytochromes c; 49 amino-acid residues are identical between T. novellus and horse cytochromes c, and 50 residues identical between N. winogradskyi and horse cytochromes c. However, their reactivity with cow cytochrome c oxidase is about 80% lower than the reactivity of eukaryotic cytochromes c with the cow mitochondrial oxidase, while they react with yeast cytochrome c peroxidase as rapidly as eukaryotic cytochromes c. The numbers of identical amino-acid residues between T. novellus and animal cytochromes c are 45-53 and those between N. winogradskyi and animal cytochromes c 47-53, while those between the two bacterial cytochromes and yeast and protozoan cytochromes c are around 40. Thus, N. winogradskyi and T. novellus cytochromes c are more similar to animal cytochromes c than to yeast and protozoan cytochromes c on the basis of the amino-acid sequence.

  7. Calcium transport in vesicles energized by cytochrome oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Rosier, Randy N. [Univ. of Rochester, NY (United States)

    1979-01-01

    Experiments on the reconstitution of cytochrome oxidase into phospholipid vesicles were carried out using techniques of selectivity energizing the suspensions with ascorbate and cytochrome c or ascorbate, PMS, and internally trapped cytochrome c. It was found that the K+ selective ionophore valinomycin stimulated the rate of respiration of cytochrome oxidase vesicles regardless of the direction of the K+ flux across the vesicle membranes. The stimulation occurred in the presence of protonophoric uncouplers and in the complete absence of potassium or in detergent-lysed suspensions. Gramicidin had similar effects and it was determined that the ionophores acted by specific interaction with cytochrome oxidase rather than by the previously assumed collapse of membrane potentials. When hydrophobic proteins and appropriate coupling factors were incorporated into the cytochrome oxidase, vesicles phosphorylation of ADP could be coupled to the oxidation reaction of cytochrome oxidase. Relatively low P:O, representing poor coupling of the system, were problematical and precluded measurements of protonmotive force. However the system was used to study ion translocation.

  8. EFFECT OF CROSSLINKING ON MITOCHONDRIAL CYTOCHROME c OXIDASE

    Energy Technology Data Exchange (ETDEWEB)

    Swanson, Maurice; Packer, Lester

    1979-12-01

    Purified and reconstituted cytochrome {und c} oxidase and mitochondria were crosslinked with biimidates in the presence and absence of cytochrome {und c}. These experiments indicate that oxidase subunit interactions are required for activity and that cytochrome {und c} mobility may be required for electron transport activity. Biimidate treatment of purified and reconstituted oxidase crosslinks all of the oxidase protomers except subunit I when {ge} 20% of the free amines are modified and inhibits steady state oxidase activity. Transient kinetics of ferrocytochrome {und c} oxidation and ferricytochrome {und a} reduction indicates inhibition of electron transfer from heme {und a} to heme {und a}{sub 3}. Crosslinking oxidase molecules to form large aggregates displaying rotational correlation times {ge} 1 ms does not affect oxidase activity. Crosslinking of mitochondria covalently binds the bc{sub 1} and {und aa}{sub 3} complexes to cytochrome {und c}, and inhibits steady-state oxidase activity considerably more than in the case of the purified oxidase. Addition of cytochrome {und c} to the purified oxidase or to {und c}-depleted mitoplasts increases inhibition slightly. Cytochrome {und c} oligomers act as competitive inhibitors of native {und c}, however, crosslinking of cytochrome {und c} to {und c}-depleted mitoplasts or purified oxidase (with dimethyl suberimidate or hetrobifunctional crosslinking reagents) results in a catalytically inactive complex.

  9. Evaluation of chemical composition, antioxidant, antibacterial, cytotoxic and apoptotic effects of Aloysia citrodora extract on colon cancer cell line

    OpenAIRE

    Amir Mirzaie; Seyed Ataollah Sadat Shandiz; Hassan Noorbazargan; Elahe Ali Asgary

    2016-01-01

    Background: Aloysia citrodora belongs to the Verbenaceae family of plants, a well-known herbal medicine in Iran. The aim of the present study was to investigate the chemical composition, antioxidant, antibacterial, cytotoxic and apoptotic effect of A. citrodora extract against human colon cancer (HT29) cells by using real-time polymerase chain reaction and flow-cytometry methods. Methods: This experimental study was carried out in Islamic Azad University, East Tehran Branch, from March to...

  10. Optimization of chemically defined cell culture media--replacing fetal bovine serum in mammalian in vitro methods

    DEFF Research Database (Denmark)

    van der Valk, J; Brunner, D; De Smet, K

    2010-01-01

    Quality assurance is becoming increasingly important. Good laboratory practice (GLP) and good manufacturing practice (GMP) are now established standards. The biomedical field aims at an increasing reliance on the use of in vitro methods. Cell and tissue culture methods are generally fast, cheap......, reproducible and reduce the use of experimental animals. Good cell culture practice (GCCP) is an attempt to develop a common standard for in vitro methods. The implementation of the use of chemically defined media is part of the GCCP. This will decrease the dependence on animal serum, a supplement...

  11. Nano-hydroxyapatite colloid suspension coated on chemically modified porous silicon by cathodic bias: a suitable surface for cell culture

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Alejandra [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Centro de Electroquimica y Energia Quimica de la Universidad de Costa Rica (CELEQ), Universidad de Costa Rica, 2060 (Costa Rica); Gonzalez, Jerson [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Garcia-Pineres, Alfonso [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Centro de Investigacion en Biologia Celular y Molecular (CIBCM), Universidad de Costa Rica, 2060 (Costa Rica); Montero, Mavis L. [Escuela de Quimica, Universidad de Costa Rica, 2060 (Costa Rica); Centro de Electroquimica y Energia Quimica de la Universidad de Costa Rica (CELEQ), Universidad de Costa Rica, 2060 (Costa Rica); Centro de Ciencia e Ingenieria en Materiales (CICIMA), Universidad de Costa Rica, 2060 (Costa Rica)

    2011-06-15

    The properties of porous silicon make it an interesting material for biological applications. However, porous silicon is not an appropriate surface for cell growth. Surface modification is an alternative that could afford a bioactive material. In this work, we report a method to yield materials by modification of the porous silicon surface with hydroxyapatite of nanometric dimensions, produced using an electrochemical process and coated on macroporous silicon substrates by cathodic bias. The chemical nature of the calcium phosphate deposited on the substrates after the experimental process and the amount of cell growth on these surfaces were characterized. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Data on interaction between adeno-associated virus and U87 cell via cRGD chemical modification

    Directory of Open Access Journals (Sweden)

    Chuanling Zhang

    2016-06-01

    Full Text Available RGD tripeptide is a specific, high-affinity ligand for integrin, which is highly expressed in cancer cells. We previously reported that cRGD chemically modified AAV2 (AAV2N587+1/azido+RGD showed significantly enhanced infectivity compared to RGD genetically inserted AAV2 (AAV2N587+RGD (10.1016/j.biomaterials.2015.11.066 [1]. Herein we provide the binding ability analysis of RGD modified AAV2 and U87 cell by flow cytometry and the theoretical working model of RGD–αvβ3 integrin interaction.

  13. Impact of Dissolved Oxygen during UV-Irradiation on the Chemical Composition and Function of CHO Cell Culture Media.

    Science.gov (United States)

    Meunier, Sarah M; Todorovic, Biljana; Dare, Emma V; Begum, Afroza; Guillemette, Simon; Wenger, Andrew; Saxena, Priyanka; Campbell, J Larry; Sasges, Michael; Aucoin, Marc G

    2016-01-01

    Ultraviolet (UV) irradiation is advantageous as a sterilization technique in the biopharmaceutical industry since it is capable of targeting non-enveloped viruses that are typically challenging to destroy, as well as smaller viruses that can be difficult to remove via conventional separation techniques. In this work, we investigated the influence of oxygen in the media during UV irradiation and characterized the effect on chemical composition using NMR and LC-MS, as well as the ability of the irradiated media to support cell culture. Chemically defined Chinese hamster ovary cell growth media was irradiated at high fluences in a continuous-flow UV reactor. UV-irradiation caused the depletion of pyridoxamine, pyridoxine, pyruvate, riboflavin, tryptophan, and tyrosine; and accumulation of acetate, formate, kynurenine, lumichrome, and sarcosine. Pyridoxamine was the only compound to undergo complete degradation within the fluences considered; complete depletion of pyridoxamine was observed at 200 mJ/cm2. Although in both oxygen- and nitrogen-saturated media, the cell culture performance was affected at fluences above 200 mJ/cm2, there was less of an impact on cell culture performance in the nitrogen-saturated media. Based on these results, minimization of oxygen in cell culture media prior to UV treatment is recommended to minimize the negative impact on sensitive media.

  14. Impact of Dissolved Oxygen during UV-Irradiation on the Chemical Composition and Function of CHO Cell Culture Media.

    Directory of Open Access Journals (Sweden)

    Sarah M Meunier

    Full Text Available Ultraviolet (UV irradiation is advantageous as a sterilization technique in the biopharmaceutical industry since it is capable of targeting non-enveloped viruses that are typically challenging to destroy, as well as smaller viruses that can be difficult to remove via conventional separation techniques. In this work, we investigated the influence of oxygen in the media during UV irradiation and characterized the effect on chemical composition using NMR and LC-MS, as well as the ability of the irradiated media to support cell culture. Chemically defined Chinese hamster ovary cell growth media was irradiated at high fluences in a continuous-flow UV reactor. UV-irradiation caused the depletion of pyridoxamine, pyridoxine, pyruvate, riboflavin, tryptophan, and tyrosine; and accumulation of acetate, formate, kynurenine, lumichrome, and sarcosine. Pyridoxamine was the only compound to undergo complete degradation within the fluences considered; complete depletion of pyridoxamine was observed at 200 mJ/cm2. Although in both oxygen- and nitrogen-saturated media, the cell culture performance was affected at fluences above 200 mJ/cm2, there was less of an impact on cell culture performance in the nitrogen-saturated media. Based on these results, minimization of oxygen in cell culture media prior to UV treatment is recommended to minimize the negative impact on sensitive media.

  15. Methoxyflurane acts at the substrate binding site of cytochrome P450 LM2 to induce a dependence on cytochrome b5.

    Science.gov (United States)

    Lipka, J J; Waskell, L A

    1989-01-01

    Rabbit cytochrome P450 isozyme 2 requires cytochrome b5 to metabolize the volatile anesthetic methoxyflurane but not the substrate benzphetamine [E. Canova-Davis and L. Waskell (1984) J. Biol. Chem. 259, 2541-2546]. To determine whether the requirement for cytochrome b5 for methoxyflurane oxidation is mediated by an allosteric effect on cytochrome P450 LM2 or cytochrome P450 reductase, we have investigated whether this anesthetic can induce a role for cytochrome b5 in benzphetamine metabolism. Using rabbit liver microsomes and antibodies raised in guinea pigs against rabbit cytochrome b5, we found that methoxyflurane did not create a cytochrome b5 requirement for benzphetamine metabolism. Methoxyflurane also failed to induce a role for cytochrome b5 in benzphetamine metabolism in the purified, reconstituted mixed function oxidase system. Studies of the reaction kinetics established that in the absence of cytochrome b5, methoxyflurane and benzphetamine are competitive inhibitors, and that in the presence of cytochrome b5, benzphetamine and methoxyflurane are two alternate substrates in competition for a single site on the same enzyme. These results all indicate that the methoxyflurane-induced cytochrome b5 dependence of the mixed function oxidase cytochrome P450 LM2 system is a direct result of the interaction between methoxyflurane and the substrate binding site of cytochrome P450 LM2 and suggest the focus of future studies of this question.

  16. Inhibition of cytochrome p450 enzymes by quinones and anthraquinones.

    Science.gov (United States)

    Sridhar, Jayalakshmi; Liu, Jiawang; Foroozesh, Maryam; Klein Stevens, Cheryl L

    2012-02-20

    In silico docking studies and quantitative structure-activity relationship analysis of a number of in-house cytochrome P450 inhibitors have revealed important structural characteristics that are required for a molecule to function as a good inhibitor of P450 enzymes 1A1, 1A2, 2B1, and/or 2A6. These insights were incorporated into the design of pharmacophores used for a 2D search of the Chinese medicine database. Emodin, a natural anthraquinone isolated from Rheum emodi and known to be metabolized by cytochrome P450 enzymes, was one of the hits and was used as the lead compound. Emodin was found to inhibit P450s 1A1, 1A2, and 2B1 with IC(50) values of 12.25, 3.73, and 14.89 μM, respectively. On the basis of the emodin molecular structure, further similarity searches of the PubChem and ZINC chemical databases were conducted resulting in the identification of 12 emodin analogues for testing against P450s 1A1-, 1A2-, 2B1-, and 2A6-dependent activities. 1-Amino-4-chloro-2-methylanthracene-9,10-dione (compound 1) showed the best inhibition potency for P450 1A1 with an IC(50) value of 0.40 μM. 1-Amino-4-chloro-2-methylanthracene-9,10-dione (compound 1) and 1-amino-4-hydroxyanthracene-9,10-dione (compound 2) both inhibited P450 1A2 with the same IC(50) value of 0.53 μM. In addition, compound 1 acted as a mechanism-based inhibitor of cytochrome P450s 1A1 and 1A2 with K(I) and K(inactivation) values of 5.38 μM and 1.57 min(-1) for P450 1A1 and 0.50 μM and 0.08 min(-1) for P450 1A2. 2,6-Di-tert-butyl-5-hydroxynaphthalene-1,4-dione (compound 8) directly inhibited P450 2B1 with good selectivity and inhibition potency (IC(50) = 5.66 μM). Docking studies using the 3D structures of the enzymes were carried out on all of the compounds. The binding modes of these compounds revealed the structural characteristics responsible for their potency and selectivity. Compound 1, which is structurally similar to compound 2 with the presence of an amino group at position 1, showed a

  17. Human metabolism and metabolic interactions of deployment-related chemicals.

    Science.gov (United States)

    Hodgson, Ernest; Rose, Randy L

    2005-01-01

    It has been suggested that chemicals and, more specifically, chemical interactions, are involved as causative agents in deployment-related illnesses. Unfortunately, this hypothesis has proven difficult to test, because toxicological investigations of deployment-related chemicals are usually carried out on surrogate animals and are difficult to extrapolate to humans. Other parts of the problem, such as the definition of variation within human populations and the development of methods for designating groups or individuals at significantly greater risk, cannot be carried out on surrogate animals, and the data must be derived from humans. The relatively recent availability of human cell.fractions, such as microsomes, cytosol, etc., human cells such as primary hepatocytes, recombinant human enzymes, and their isoforms and polymorphic variants has enabled a significant start to be made in developing the human data needed. These initial studies have examined the human metabolism by cytochrome P450, other phase I enzymes, and their isoforms and, in some cases, their polymorphic variants of compounds such as chlorpyrifos, carbaryl, DEET, permethrin, and pyridostigmine bromide, and, to a lesser extent, other chemicals from the same chemical and use classes, including solvents, jet fuel components, and sulfur mustard metabolites. A number of interactions at the metabolic level have been described both with respect to other xenobiotics and to endogenous metabolites. Probably the most dramatic have been seen in the ability of chlorpyrifos to inhibit not only the metabolism of other xenobiotics such as carbaryl and DEET but also to inhibit the metabolism of steroid hormones.

  18. The question of histidine content in c-type cytochromes.

    Science.gov (United States)

    Cusanovich, M A; Meyer, T; Tedro, S M; Kamen, M D

    1971-03-01

    Reports that histidine may not occur in heme peptides derived from c-type cytochromes isolated from chloroplasts of Euglena gracilis and Porphyra sp. have not been substantiated in the present investigation, in which the amino acid composition and a partial sequence were determined for a heme peptide derived from the c-type cytochromes of a strain of Euglena closely related to that used in the previous studies. It is concluded that no evidence exists to challenge the generalization that histidine is always present vicinal to the hemebinding site in c-type cytochromes.

  19. Sequential unfolding of the two-domain protein Pseudomonas stutzeri cytochrome c(4)

    DEFF Research Database (Denmark)

    Andersen, Niels Højmark; Jensen, Thomas Jon; Nørgaard, Allan

    2002-01-01

    , and different spin states of the oxidised haem groups. We have studied unfolding of oxidised P. stutzeri cyt c(4) induced thermally and by chemical denaturants Horse heart cyt c was a reference molecule. Isothermal unfolding induced by guanidinium chloride and acid was followed by Soret. alpha/beta. and 701-nm...... chloride up to 0.4 M is present. This reflects different chemical action in chemical and thermal unfolding. Acid-induced unfolding kinetics was addressed by pH jumps using diode array stopped-flow techniques, Three kinetic phases in the 701 nm Fe-Met marker band. and four phases in the Soret and alpha/beta......F stutzeri cytochrome c. is a di-haem protein, composed of two globular domains each with His-Met coordinated haem. and a hydrogen bond network between the domains. The domain foldings are highly symmetric but with specific differences including structural differences of ligand coordination...

  20. Isolation and Characterization of a Hybrid Respiratory Supercomplex Consisting of Mycobacterium tuberculosis Cytochrome bcc and Mycobacterium smegmatis Cytochrome aa3.

    Science.gov (United States)

    Kim, Mi-Sun; Jang, Jichan; Ab Rahman, Nurlilah Binte; Pethe, Kevin; Berry, Edward A; Huang, Li-Shar

    2015-06-05

    Recently, energy production pathways have been shown to be viable antitubercular drug targets to combat multidrug-resistant tuberculosis and eliminate pathogen in the dormant state. One family of drugs currently under development, the imidazo[1,2-a]pyridine derivatives, is believed to target the pathogen's homolog of the mitochondrial bc1 complex. This complex, denoted cytochrome bcc, is highly divergent from mitochondrial Complex III both in subunit structure and inhibitor sensitivity, making it a good target for drug development. There is no soluble cytochrome c in mycobacteria to transport electrons from the bcc complex to cytochrome oxidase. Instead, the bcc complex exists in a "supercomplex" with a cytochrome aa3-type cytochrome oxidase, presumably allowing direct electron transfer. We describe here purification and initial characterization of the mycobacterial cytochrome bcc-aa3 supercomplex using a strain of M. smegmatis that has been engineered to express the M. tuberculosis cytochrome bcc. The resulting hybrid supercomplex is stable during extraction and purification in the presence of dodecyl maltoside detergent. It is hoped that this purification procedure will potentiate functional studies of the complex as well as crystallographic studies of drug binding and provide structural insight into a third class of the bc complex superfamily. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  1. Concise review: chemical approaches for modulating lineage-specific stem cells and progenitors.

    Science.gov (United States)

    Xu, Tao; Zhang, Mingliang; Laurent, Timothy; Xie, Min; Ding, Sheng

    2013-05-01

    Generation and manipulation of lineage-restricted stem and progenitor cells in vitro and/or in vivo are critical for the development of stem cell-based clinical therapeutics. Lineage-restricted stem and progenitor cells have many advantageous qualities, including being able to efficiently engraft and differentiate into desirable cell types in vivo after transplantation, and they are much less tumorigenic than pluripotent cells. Generation of lineage-restricted stem and progenitor cells can be achieved by directed differentiation from pluripotent stem cells or lineage conversion from easily obtained somatic cells. Small molecules can be very helpful in these processes since they offer several important benefits. For example, the risk of tumorigenesis is greatly reduced when small molecules are used to replace integrated transcription factors, which are widely used in cell fate conversion. Furthermore, small molecules are relatively easy to apply, optimize, and manufacture, and they can more readily be developed into conventional pharmaceuticals. Alternatively, small molecules can be used to expand or selectively control the differentiation of lineage-restricted stem and progenitor cells for desirable therapeutics purposes in vitro or in vivo. Here we summarize recent progress in the use of small molecules for the expansion and generation of desirable lineage-restricted stem and progenitor cells in vitro and for selectively controlling cell fate of lineage-restricted stem and progenitor cells in vivo, thereby facilitating stem cell-based clinical applications.

  2. Generation of Bladder Urothelium from Human Pluripotent Stem Cells under Chemically Defined Serum- and Feeder-Free System

    Directory of Open Access Journals (Sweden)

    Minyong Kang

    2014-04-01

    Full Text Available Human stem cells are promising sources for bladder regeneration. Among several possible sources, pluripotent stem cells are the most fascinating because they can differentiate into any cell type, and proliferate limitlessly in vitro. Here, we developed a protocol for differentiation of human pluripotent stem cells (hPSCs into bladder urothelial cells (BUCs under a chemically defined culture system. We first differentiated hPSCs into definitive endoderm (DE, and further specified DE cells into BUCs by treating retinoic acid under a keratinocyte-specific serum free medium. hPSC-derived DE cells showed significantly expressed DE-specific genes, but did not express mesodermal or ectodermal genes. After DE cells were specified into BUCs, they notably expressed urothelium-specific genes such as UPIb, UPII, UPIIIa, P63 and CK7. Immunocytochemistry showed that BUCs expressed UPII, CK8/18 and P63 as well as tight junction molecules, E-CADHERIN and ZO-1. Additionally, hPSCs-derived BUCs exhibited low permeability in a FITC-dextran permeability assay, indicating BUCs possessed the functional units of barrier on their surfaces. However, BUCs did not express the marker genes of other endodermal lineage cells (intestine and liver as well as mesodermal or ectodermal lineage cells. In summary, we sequentially differentiated hPSCs into DE and BUCs in a serum- and feeder-free condition. Our differentiation protocol will be useful for producing cells for bladder regeneration and studying normal and pathological development of the human bladder urothelium in vitro.

  3. Flavopiridol suppresses tumor necrosis factor-induced activation of activator protein-1, c-Jun N-terminal kinase, p38 mitogen-activated protein kinase (MAPK), p44/p42 MAPK, and Akt, inhibits expression of antiapoptotic gene products, and enhances apoptosis through cytochrome c release and caspase activation in human myeloid cells.

    Science.gov (United States)

    Takada, Yasunari; Sethi, Gautam; Sung, Bokyung; Aggarwal, Bharat B

    2008-05-01

    Although flavopiridol, a semisynthetic flavone, was initially thought to be a specific inhibitor of cyclin-dependent kinases, it has now been shown that flavopiridol mediates antitumor responses through mechanism(s) yet to be defined. We have shown previously that flavopiridol abrogates tumor necrosis factor (TNF)-induced nuclear factor-kappaB (NF-kappaB) activation. In this report, we examined whether this flavone affects other cellular responses activated by TNF. TNF is a potent inducer of activator protein-1 (AP-1), and flavopiridol abrogated this activation in a dose- and time-dependent manner. Flavopiridol also suppressed AP-1 activation induced by various carcinogens and inflammatory stimuli. When examined for its effect on other signaling pathways, flavopiridol inhibited TNF-induced activation of various mitogen-activated protein kinases, including c-Jun NH(2)-terminal kinase (JNK), p38 mitogen-activated protein kinase (MAPK), and p44/p42 MAPK. It is noteworthy that this flavone also suppressed TNF-induced activation of Akt, a cell survival kinase, and expression of various antiapoptotic proteins, such as IAP-1, IAP-2, XIAP, Bcl-2, Bcl-xL, and TRAF-1. Flavopiridol also inhibited the TNF-induced induction of intercellular adhesion molecule-1, c-Myc, and c-Fos, all known to mediate tumorigenesis. Moreover, TNF-induced apoptosis was enhanced by flavopiridol through activation of the bid-cytochrome-caspase-9-caspase-3 pathway. Overall, our results clearly suggest that flavopiridol interferes with the TNF cell-signaling pathway, leading to suppression of antiapoptotic mechanisms and enhancement of apoptosis.

  4. Use of a gas-sensor array for detecting volatile organic compounds (VOC) in chemically induced cells.

    Science.gov (United States)

    Pasini, Patrizia; Powar, Nilesh; Gutierrez-Osuna, Ricardo; Daunert, Sylvia; Roda, Aldo

    2004-01-01

    An application of gas sensors for rapid bioanalysis is presented. An array of temperature-modulated semiconductor sensors was used to characterize the headspace above a cell culture. Recombinant Saccharomyces cerevisiae yeast cells, able to respond to 17 beta-estradiol by producing a reporter protein, were used as a model system. Yeast cells had the DNA sequence of the human estrogen receptor stably integrated into the genome, and contained expression plasmids carrying estrogen-responsive sequences and the reporter gene lac-Z, encoding the enzyme beta-galactosidase. The sensor-response profiles showed small but noticeable discrimination between cell samples induced with 17 beta-estradiol and non-induced cell samples. The sensor array was capable of detecting changes in the volatile organic compound composition of the headspace above the cultured cells, which can be associated with metabolic changes induced by a chemical compound. This finding suggests the possibility of using cross-selective gas-sensor arrays for analysis of drugs or bioactive molecules through their interaction with cell systems, with the advantage of providing information on their bioavailability.

  5. Scaling up a chemically-defined aggregate-based suspension culture system for neural commitment of human pluripotent stem cells.

    Science.gov (United States)

    Miranda, Cláudia C; Fernandes, Tiago G; Diogo, M Margarida; Cabral, Joaquim M S

    2016-12-01

    The demand of high cell numbers for applications in cellular therapies and drug screening requires the development of scalable platforms capable to generating highly pure populations of tissue-specific cells from human pluripotent stem cells. In this work, we describe the scaling-up of an aggregate-based culture system for neural induction of human induced pluripotent stem cells (hiPSCs) under chemically-defined conditions. A combination of non-enzymatic dissociation and rotary agitation was successfully used to produce homogeneous populations of hiPSC aggregates with an optimal (140 μm) and narrow distribution of diameters (coefficient of variation of 21.6%). Scalable neural commitment of hiPSCs as 3D aggregates was performed in 50 mL spinner flasks, and the process was optimized using a factorial design approach, involving parameters such as agitation rate and seeding density. We were able to produce neural progenitor cell cultures, that at the end of a 6-day neural induction process contained less than 3% of Oct4-positive cells and that, after replating, retained more than 60% of Pax6-positive neural cells. The results here presented should set the stage for the future generation of a clinically relevant number of human neural progenitors for transplantation and other biomedical applications using controlled, automated and reproducible large-scale bioreactor culture systems. Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Bioorthogonal chemical imaging of metabolic changes during epithelial-mesenchymal transition of cancer cells by stimulated Raman scattering microscopy

    Science.gov (United States)

    Zhang, Luyuan; Min, Wei

    2017-10-01

    Study of metabolic changes during epithelial-mesenchymal transition (EMT) of cancer cells is important for basic understanding and therapeutic management of cancer progression. We here used metabolic labeling and stimulated Raman scattering (SRS) microscopy, a strategy of bioorthogonal chemical imaging, to directly visualize changes in anabolic metabolism during cancer EMT at a single-cell level. MCF-7 breast cancer cell is employed as a model system. Four types of metabolites (amino acids, glucose, fatty acids, and choline) are labeled with either deuterium or alkyne (C≡C) tag. Their intracellular incorporations into MCF-7 cells before or after EMT are visualized by SRS imaging targeted at the signature vibration frequency of C-D or C≡C bonds. Overall, after EMT, anabolism of amino acids, glucose, and choline is less active, reflecting slower protein and membrane synthesis in mesenchymal cells. Interestingly, we also observed less incorporation of glucose and palmitate acids into membrane lipids, but more of them into lipid droplets in mesenchymal cells. This result indicates that, although mesenchymal cells synthesize fewer membrane lipids, they are actively storing energy into lipid droplets, either through de novo lipogenesis from glucose or direct scavenging of exogenous free fatty acids. Hence, metabolic labeling coupled with SRS can be a straightforward method in imaging cancer metabolism.

  7. Inferences of drug responses in cancer cells from cancer genomic features and compound chemical and therapeutic properties

    Science.gov (United States)

    Wang, Yongcui; Fang, Jianwen; Chen, Shilong

    2016-09-01

    Accurately predicting the response of a cancer patient to a therapeutic agent is a core goal of precision medicine. Existing approaches were mainly relied primarily on genomic alterations in cancer cells that have been treated with different drugs. Here we focus on predicting drug response based on integration of the heterogeneously pharmacogenomics data from both cell and drug sides. Through a systematical approach, named as PDRCC (Predict Drug Response in Cancer Cells), the cancer genomic alterations and compound chemical and therapeutic properties were incorporated to determine the chemotherapeutic response in cancer patients. Using the Cancer Cell Line Encyclopedia (CCLE) study as the benchmark dataset, all pharmacogenomics data exhibited their roles in inferring the relationships between cancer cells and drugs. When integrating both genomic resources and compound information, the prediction coverage was significantly increased. The validity of PDRCC was also supported by its effective in uncovering the unknown cell-drug associations with database and literature evidences. It set the stage for clinical testing of novel therapeutic strategies, such as the sensitive association between cancer cell ‘A549_LUNG’ and compound ‘Topotecan’. In conclusion, PDRCC offers the possibility for faster, safer, and cheaper the development of novel anti-cancer therapeutics in the early-stage clinical trails.

  8. Chemical inhibition of fatty acid synthase: molecular docking analysis and biochemical validation in ocular cancer cells

    National Research Council Canada - National Science Library

    Deepa, P R; Vandhana, S; Muthukumaran, S; Umashankar, V; Jayanthi, U; Krishnakumar, S

    2010-01-01

    ...: cerulenin, triclosan and orlistat. The IC50 and dose-dependent sensitivity of cancer cells to FASN inhibitors decrease in biologic enzyme activity, and cell morphology alterations were analysed...

  9. Chemical and structural analysis of Eucalyptus globulus and E. camaldulensis leaf cuticles: a lipidized cell wall region

    Directory of Open Access Journals (Sweden)

    Paula eGuzmán

    2014-09-01

    Full Text Available The plant cuticle has traditionally been conceived as an independent hydrophobic layer that covers the external epidermal cell wall. Due to its complexity, the existing relationship between cuticle chemical composition and ultra-structure remains unclear to date. This study aimed to examine the link between chemical composition and structure of isolated, adaxial leaf cuticles of Eucalyptus camaldulensis and E. globulus by the gradual extraction and identification of lipid constituents (cutin and soluble lipids, coupled to spectroscopic and microscopic analyses. The soluble compounds and cutin monomers identified could not be assigned to a concrete internal cuticle ultra-structure. After cutin depolymerization, a cellulose network resembling the cell wall was observed, with different structural patterns in the regions ascribed to the cuticle proper and cuticular layer, respectively. Our results suggest that the current cuticle model should be revised, stressing the presence and major role of cell wall polysaccharides. It is concluded that the cuticle may be interpreted as a modified cell wall region which contains additional lipids. The major heterogeneity of the plant cuticle makes it difficult to establish a direct link between cuticle chemistry and structure with the existing methodologies.

  10. Rapidly developed squamous cell carcinoma after laser therapy used to treat chemical burn wound: a case report.

    Science.gov (United States)

    Cho, Hyung-Rok; Kwon, Soon-Sung; Chung, Seum; Kie, Jeong-Hae

    2015-02-07

    In chronic wounds, especially burn scars, malignant tumors can arise. However, it is rare for a subacute burn injury to change to a malignant lesion within one month. Moreover, a case of squamous cell carcinoma arising from HeNe laser therapy after a chemical burn has never been reported. In this report, we examine a rare case of squamous cell carcinoma arising from HeNe laser therapy after a chemical burn. Because pathologic investigations were made from the first operation, both early detection of the squamous cell carcinoma and consideration of the HeNe laser therapy as a risk factor for the skin cancer were possible. The cancer was completely removed and reconstruction of the defect was successfully achieved in a timely manner. Although there has as yet been no reported case of squamous cell carcinoma induced by laser therapy, it is important for clinicians to recognize both the possibility of laser-induced cancer and the rapid change of cancer, so they can provide appropriate and timely treatment.

  11. Chemical and structural analysis of Eucalyptus globulus and E. camaldulensis leaf cuticles: a lipidized cell wall region.

    Science.gov (United States)

    Guzmán, Paula; Fernández, Victoria; Graça, José; Cabral, Vanessa; Kayali, Nour; Khayet, Mohamed; Gil, Luis

    2014-01-01

    The plant cuticle has traditionally been conceived as an independent hydrophobic layer that covers the external epidermal cell wall. Due to its complexity, the existing relationship between cuticle chemical composition and ultra-structure remains unclear to date. This study aimed to examine the link between chemical composition and structure of isolated, adaxial leaf cuticles of Eucalyptus camaldulensis and E. globulus by the gradual extraction and identification of lipid constituents (cutin and soluble lipids), coupled to spectroscopic and microscopic analyses. The soluble compounds and cutin monomers identified could not be assigned to a concrete internal cuticle ultra-structure. After cutin depolymerization, a cellulose network resembling the cell wall was observed, with different structural patterns in the regions ascribed to the cuticle proper and cuticular layer, respectively. Our results suggest that the current cuticle model should be revised, stressing the presence and major role of cell wall polysaccharides. It is concluded that the cuticle may be interpreted as a modified cell wall region which contains additional lipids. The major heterogeneity of the plant cuticle makes it difficult to establish a direct link between cuticle chemistry and structure with the existing methodologies.

  12. High-Performance Black Multicrystalline Silicon Solar Cells by a Highly Simplified Metal-Catalyzed Chemical Etching Method

    KAUST Repository

    Ying, Zhiqin

    2016-05-20

    A wet-chemical surface texturing technique, including a two-step metal-catalyzed chemical etching (MCCE) and an extra alkaline treatment, has been proven as an efficient way to fabricate high-efficiency black multicrystalline (mc) silicon solar cells, whereas it is limited by the production capacity and the cost cutting due to the complicated process. Here, we demonstrated that with careful control of the composition in etching solution, low-aspect-ratio bowl-like nanostructures with atomically smooth surfaces could be directly achieved by improved one-step MCCE and with no posttreatment, like alkali solution. The doublet surface texture of implementing this nanobowl structure upon the industrialized acidic-textured surface showed concurrent improvement in optical and electrical properties for realizing 18.23% efficiency mc-Si solar cells (156 mm × 156 mm), which is sufficiently higher than 17.7% of the solely acidic-textured cells in the same batch. The one-step MCCE method demonstrated in this study may provide a cost-effective way to manufacture high-performance mc-Si solar cells for the present photovoltaic industry. © 2016 IEEE.

  13. Chemical modification allows phallotoxins and amatoxins to be used as tools in cell biology

    OpenAIRE

    Jan Anderl; Hartmut Echner; Heinz Faulstich

    2012-01-01

    Summary Phallotoxins inhibit the dynamics of microfilaments in cells and lead to apoptosis. Due to poor cellular uptake these effects cannot be studied in live cells, even at millimolar toxin concentrations, nor can phalloidin be used for the elimination of tumor cells. Uptake is greatly enhanced by conjugation of phallotoxins to either lipophilic or polycationic moieties, such as oleic acid, polylysine, or Tat-peptide. These conjugates were lethally toxic for cells, e.g., mouse fibroblasts o...

  14. Identifying developmental toxicity pathways for a subset of ToxCast chemicals using human embryonic stem cells and metabolomics

    Energy Technology Data Exchange (ETDEWEB)

    Kleinstreuer, N.C., E-mail: kleinstreuer.nicole@epa.gov [NCCT, US EPA, RTP, NC 27711 (United States); Smith, A.M.; West, P.R.; Conard, K.R.; Fontaine, B.R. [Stemina Biomarker Discovery, Inc., Madison, WI 53719 (United States); Weir-Hauptman, A.M. [Covance, Inc., Madison, WI 53704 (United States); Palmer, J.A. [Stemina Biomarker Discovery, Inc., Madison, WI 53719 (United States); Knudsen, T.B.; Dix, D.J. [NCCT, US EPA, RTP, NC 27711 (United States); Donley, E.L.R. [Stemina Biomarker Discovery, Inc., Madison, WI 53719 (United States); Cezar, G.G. [Stemina Biomarker Discovery, Inc., Madison, WI 53719 (United States); University of Wisconsin-Madison, Madison, WI 53706 (United States)

    2011-11-15

    Metabolomics analysis was performed on the supernatant of human embryonic stem (hES) cell cultures exposed to a blinded subset of 11 chemicals selected from the chemical library of EPA's ToxCast Trade-Mark-Sign chemical screening and prioritization research project. Metabolites from hES cultures were evaluated for known and novel signatures that may be indicative of developmental toxicity. Significant fold changes in endogenous metabolites were detected for 83 putatively annotated mass features in response to the subset of ToxCast chemicals. The annotations were mapped to specific human metabolic pathways. This revealed strong effects on pathways for nicotinate and nicotinamide metabolism, pantothenate and CoA biosynthesis, glutathione metabolism, and arginine and proline metabolism pathways. Predictivity for adverse outcomes in mammalian prenatal developmental toxicity studies used ToxRefDB and other sources of information, including Stemina Biomarker Discovery's predictive DevTox Registered-Sign model trained on 23 pharmaceutical agents of known developmental toxicity and differing potency. The model initially predicted developmental toxicity from the blinded ToxCast compounds in concordance with animal data with 73% accuracy. Retraining the model with data from the unblinded test compounds at one concentration level increased the predictive accuracy for the remaining concentrations to 83%. These preliminary results on a 11-chemical subset of the ToxCast chemical library indicate that metabolomics analysis of the hES secretome provides information valuable for predictive modeling and mechanistic understanding of mammalian developmental toxicity. -- Highlights: Black-Right-Pointing-Pointer We tested 11 environmental compounds in a hESC metabolomics platform. Black-Right-Pointing-Pointer Significant changes in secreted small molecule metabolites were observed. Black-Right-Pointing-Pointer Perturbed mass features map to pathways critical for normal

  15. Oxygen and xenobiotic reductase activities of cytochrome P450.

    NARCIS (Netherlands)

    Goeptar, A.R.; Scheerens, H.; Vermeulen, N.P.E.

    1995-01-01

    The oxygen reductase and xenobiotic reductase activities of cytochrome P450 (P450) are reviewed. During the oxygen reductase activity of P450, molecular oxygen is reduced to superoxide anion radicals (O

  16. Competing modes of peroxyacid flux through cytochrome P-450

    National Research Council Canada - National Science Library

    M B McCarthy; R E White

    1983-01-01

    In the presence of peroxyphenylacetic acid and a hydroxylatable substrate, cytochrome P-450LM2 catalyzes two reactions which proceed concurrently, decarboxylation of the peroxyacid and hydroxylation of substrate...

  17. Dissecting the Cytochrome P450 1A2- and 3A4-Mediated Metabolism of Aflatoxin B1 in Ligand and Protein Contributions

    DEFF Research Database (Denmark)

    Bonomo, Silvia; Jørgensen, Flemming Steen; Olsen, Lars

    2017-01-01

    Aflatoxin B1 (AFB1) is a chemically intriguing compound because it has several potential sites of metabolism (SOMs), although only some of them are observed experimentally. Cytochrome P450 (CYP) 3A4 and 1A2 are the major isoforms involved in its metabolism. Here, we systematically investigate...

  18. A chemically defined culture medium containing Rho kinase inhibitor Y-27632 for the fabrication of stratified squamous epithelial cell grafts

    Energy Technology Data Exchange (ETDEWEB)

    Aslanova, Afag [Department of Surgery, Institute of Gastroenterology, Tokyo Women' s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666 (Japan); Institute of Advanced Biomedical Engineering and Science, Tokyo Women' s Medical University, TWIns, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666 (Japan); Takagi, Ryo; Yamato, Masayuki; Okano, Teruo [Institute of Advanced Biomedical Engineering and Science, Tokyo Women' s Medical University, TWIns, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666 (Japan); Yamamoto, Masakazu, E-mail: yamamoto.ige@twmu.ac.jp [Department of Surgery, Institute of Gastroenterology, Tokyo Women' s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666 (Japan)

    2015-05-01

    With the development of a culture method for stratified squamous epithelial cells, tissue-engineered epithelial cell sheets have been successfully applied as clinical cell grafts. However, the implementation of these cell sheets without the use of any animal-derived materials is highly desirable. In this study, Rho-associated protein kinase inhibitor Y-27632 was used to develop a chemically defined culture medium for the fabrication of stratified epithelial cell grafts consisting of human epidermal and oral keratinocytes, and the proliferation activity, cell morphology, and gene expressions of the keratinocytes were analyzed. The results of a colorimetric assay indicated that Y-27632 significantly promoted the proliferation of the keratinocytes in culture media both with and without fetal bovine serum (FBS), although there were no indications of Y-27632 efficacy on cell morphology and stratification of the keratinocytes in culture medium without any animal-derived materials. The results of quantitative RT-PCR revealed that gene expressions correlated with cell adhesion, cell–cell junction, proliferation markers, and stem/progenitor markers in cultured keratinocytes were not strongly affected by the addition of Y-27632 to the culture medium. Moreover, gene expressions of differentiation markers in stratified keratinocytes cultured in medium without FBS were nearly identical to those of keratinocytes co-cultured with 3T3 feeder cells. Interestingly, the expressions of differentiation markers in cultured stratified keratinocytes were suppressed by FBS, whereas they were reconstructed by either co-culture of a 3T3 feeder layer or addition of Y-27632 into the culture medium containing FBS. These findings indicate that Y-27632 is a useful supplement for the development of a chemically defined culture medium for fabrication of stratified epithelial cell grafts for clinical applications for the purpose of developing the culture medium with a lower risk of pathogen

  19. Establishment of a novel hepatocyte model that expresses four cytochrome P450 genes stably via mammalian-derived artificial chromosome for pharmacokinetics and toxicity studies.

    Science.gov (United States)

    Satoh, Daisuke; Iwado, Satoru; Abe, Satoshi; Kazuki, Kanako; Wakuri, Shinobu; Oshimura, Mitsuo; Kazuki, Yasuhiro

    2017-01-01

    The utility of HepG2 cells to assess drug metabolism and toxicity induced by chemical compounds is hampered by their low cytochrome P450 (CYP) activities. To overcome this limitation, we established HepG2 cell lines expressing major CYP enzymes involved in drug metabolism (CYP2C9, CYP2C19, CYP2D6, and CYP3A4) and CYP oxidoreductase (POR) using the mammalian-derived artificial chromosome vector. Transchromosomic HepG2 (TC-HepG2) cells expressing four CYPs and POR were used to determine time- and concentration-dependent inhibition and toxicity of several compounds by luminescence detection of CYP-specific substrates and cell viability assays. Gene expression levels of all four CYPs and POR, as well as the CYP activities, were higher in TC-HepG2 clones than in parental HepG2 cells. Additionally, the activity levels of all CYPs were reduced in a concentration-dependent manner by specific CYP inhibitors. Furthermore, preincubation of TC-HepG2 cells with CYP inhibitors known as time-dependent inhibitors (TDI) prior to the addition of CYP-specific substrates determined that CYP inhibition was enhanced in the TDI group than in the non-TDI group. Finally, the IC50 of bioactivable compound aflatoxin B1 was lower in TC-HepG2 cells than in HepG2 cells. In conclusion, the TC-HepG2 cells characterized in the current study are a highly versatile model to evaluate drug-drug interactions and hepatotoxicity in initial screening of candidate drug compounds, which require a high degree of processing capacity and reliability.

  20. Sulfite oxidase activity of cytochrome c: Role of hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Murugesan Velayutham

    2016-03-01

    Full Text Available In humans, sulfite is generated endogenously by the metabolism of sulfur containing amino acids such as methionine and cysteine. Sulfite is also formed from exposure to sulfur dioxide, one of the major environmental pollutants. Sulfite is used as an antioxidant and preservative in dried fruits, vegetables, and beverages such as wine. Sulfite is also used as a stabilizer in many drugs. Sulfite toxicity has been associated with allergic reactions characterized by sulfite sensitivity, asthma, and anaphylactic shock. Sulfite is also toxic to neurons and cardiovascular cells. Recent studies suggest that the cytotoxicity of sulfite is mediated by free radicals; however, molecular mechanisms involved in sulfite toxicity are not fully understood. Cytochrome c (cyt c is known to participate in mitochondrial respiration and has antioxidant and peroxidase activities. Studies were performed to understand the related mechanism of oxidation of sulfite and radical generation by ferric cytochrome c (Fe3+cyt c in the absence and presence of H2O2. Electron paramagnetic resonance (EPR spin trapping studies using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO were performed with sulfite, Fe3+cyt c, and H2O2. An EPR spectrum corresponding to the sulfite radical adducts of DMPO (DMPO-SO3- was obtained. The amount of DMPO-SO3- formed from the oxidation of sulfite by the Fe3+cyt c increased with sulfite concentration. In addition, the amount of DMPO-SO3- formed by the peroxidase activity of Fe3+cyt c also increased with sulfite and H2O2 concentration. From these results, we propose a mechanism in which the Fe3+cyt c and its peroxidase activity oxidizes sulfite to sulfite radical. Our results suggest that Fe3+cyt c could have a novel role in the deleterious effects of sulfite in biological systems due to increased production of sulfite radical. It also shows that the increased production of sulfite radical may be responsible for neurotoxicity and some of the injuries which

  1. Cytochrome P450-mediated cardiovascular drug interactions.

    Science.gov (United States)

    Scheen, André J

    2011-09-01

    There are numerous drug-drug interactions (DDIs) related to cardiovascular medications and many of these are mediated via the cytochrome P450 (CYP) system. Some of these may lead to serious adverse events and it is, therefore, essential that clinicians are aware of the important interactions that occur. An extensive literature search was performed to analyze the CYP-mediated cardiovascular DDIs that lead to a loss of efficacy or potential toxicity. Cardiovascular drugs may be victims or act as perpetrators of DDIs. The paper analyzes CYP-mediated drug interactions concerning anticoagulants, antiplatelet agents, antiarrhythmics, β-blockers, calcium antagonists, antihypertensive medications, lipid-lowering drugs and oral antidiabetic agents. Cardiovascular DDIs involving the CYP system are numerous. Additionally, the spectrum of drugs prescribed is constantly changing, particularly with cardiovascular diseases and it is not necessarily the case that drugs that had shown safety earlier will always show safety. Clinicians are encouraged to develop their knowledge of CYP-mediated DDIs so that they can choose safe drug combination regimens, adjust drug dosages appropriately and conduct therapeutic drug monitoring for drugs with narrow therapeutic indices.

  2. Interactions of phospholipase D and cytochrome P450 protein stability

    Energy Technology Data Exchange (ETDEWEB)

    Zangar, Richard C.; Fan, Yang-Yi; Chapkin, Robert S.

    2004-08-01

    Previous studies have suggested a relationship between cytochrome P450 (P450) 3A (CYP3A) conformation and the phospholipid composition of the associated membrane. In this study, we utilized a novel microsomal incubation system that mimics many of the characteristics of CYP3A degradation pathway that have been observed in vivo and in cultured cells to study the effects of phospholipid composition on protein stability. We found that addition of phosphatidylcholine-specific phospholipase D (PLD) stabilized CYP3A in this system, but that phosphatidylinositol-specific phospholipase C (PLC) was without effect. Addition of phosphatidic acid also stabilized CYP3A protein in the microsomes. The use of 1,10-phenanthroline (phenanthroline), an inhibitor of PLD activity, decreased CYP3A stability in incubated microsomes. Similarly, 6-h treatment of primary cultures of rat hepatocytes with phenanthroline resulted in nearly complete loss of CYP3A protein. Treatment of rats with nicardipine or dimethylsulfoxide (DMSO), which have been shown to affect CYP3A stability, altered the phospholipid composition of hepatic microsomes. It did not appear, though, that the changes in phospholipid composition that resulted from these in vivo treatments accounted for the change in CYP3A stability observed in hepatic microsomes from these animals.

  3. Multifunctional Cytochrome c: Learning New Tricks from an Old Dog.

    Science.gov (United States)

    Alvarez-Paggi, Damián; Hannibal, Luciana; Castro, María A; Oviedo-Rouco, Santiago; Demicheli, Veronica; Tórtora, Veronica; Tomasina, Florencia; Radi, Rafael; Murgida, Daniel H

    2017-11-08

    Cytochrome c (cyt c) is a small soluble heme protein characterized by a relatively flexible structure, particularly in the ferric form, such that it is able to sample a broad conformational space. Depending on the specific conditions, interactions, and cellular localization, different conformations may be stabilized, which differ in structure, redox properties, binding affinities, and enzymatic activity. The primary function is electron shuttling in oxidative phosphorylation, and is exerted by the so-called native cyt c in the intermembrane mitochondrial space of healthy cells. Under pro-apoptotic conditions, however, cyt c gains cardiolipin peroxidase activity, translocates into the cytosol to engage in the intrinsic apoptotic pathway, and enters the nucleus where it impedes nucleosome assembly. Other reported functions include cytosolic redox sensing and involvement in the mitochondrial oxidative folding machinery. Moreover, post-translational modifications such as nitration, phosphorylation, and sulfoxidation of specific amino acids induce alternative conformations with differential properties, at least in vitro. Similar structural and functional alterations are elicited by biologically significant electric fields and by naturally occurring mutations of human cyt c that, along with mutations at the level of the maturation system, are associated with specific diseases. Here, we summarize current knowledge and recent advances in understanding the different structural, dynamic, and thermodynamic factors that regulate the primary electron transfer function, as well as alternative functions and conformations of cyt c. Finally, we present recent technological applications of this moonlighting protein.

  4. Direct PEM fuel cell using "organic chemical hydrides" with zero-CO2 emission and low-crossover.

    Science.gov (United States)

    Kariya, Nobuko; Fukuoka, Atsushi; Ichikawa, Masaru

    2006-04-14

    A series of "organic chemical hydrides" such as cyclohexane, methylcyclohexane, cyclohexene, 2-propanol, and cyclohexanol were applied to the direct PEM fuel cell. High performances of the PEM fuel cell were achieved by using cyclohexane (OCV = 920 mV, PD(max) = 15 mW cm(-2)) and 2-propanol (OCV = 790 mV, PD(max) = 78 mW cm(-2)) as fuels without CO(2) emissions. The rates of fuel crossover for cyclohexane, 2-propanol, and methanol were estimated, and the rates of fuel permeation of cyclohexane and 2-propanol were lower than that of methanol. Water electrolysis and electro-reductive hydrogenation of acetone mediated by PEM were carried out and formation of 2-propanol in cathode side was observed. This system is the first example of a "rechargeable" direct fuel cell.

  5. Effect of chemically converted graphene as an electrode interfacial modifier on device-performances of inverted organic photovoltaic cells

    Science.gov (United States)

    Kang, Tae-Woon; Noh, Yong-Jin; Yun, Jin-Mun; Yang, Si-Young; Yang, Yong-Eon; Lee, Hae-Seong; Na, Seok-In

    2015-06-01

    This study examined the effects of chemically converted graphene (CCG) materials as a metal electrode interfacial modifier on device-performances of inverted organic photovoltaic cells (OPVs). As CCG materials for interfacial layers, a conventional graphene oxide (GO) and reduced graphene oxide (rGO) were prepared, and their functions on OPV-performances were compared. The inverted OPVs with CCG materials showed all improved cell-efficiencies compared with the OPVs with no metal/bulk-heterojunction (BHJ) interlayers. In particular, the inverted OPVs with reduction form of GO showed better device-performances than those with GO and better device-stability than poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS)-based inverted solar cells, showing that the rGO can be more desirable as a metal/BHJ interfacial material for fabricating inverted-configuration OPVs.

  6. The SiNx films process research by plasma-enhanced chemical vapor deposition in crystalline silicon solar cells

    Science.gov (United States)

    Chen, Bitao; Zhang, Yingke; Ouyang, Qiuping; Chen, Fei; Zhan, Xinghua; Gao, Wei

    2017-07-01

    SiNx thin film has been widely used in crystalline silicon solar cell production because of the good anti-reflection and passivation effect. We can effectively optimize the cells performance by plasma-enhanced chemical vapor deposition (PECVD) method to change deposition conditions such as temperature, gas flow ratio, etc. In this paper, we deposit a new layer of SiNx thin film on the basis of double-layers process. By changing the process parameters, the compactness of thin films is improved effectively. The NH3 passivation technology is augmented in a creative way, which improves the minority carrier lifetime. In sight of this, a significant increase is generated in the photoelectric performance of crystalline silicon solar cell.

  7. Novel nanofluidic chemical cells based on self-assembled solid-state SiO2 nanotubes

    Science.gov (United States)

    Zhu, Hao; Li, Haitao; Robertson, Joseph W. F.; Balijepalli, Arvind; Krylyuk, Sergiy; Davydov, Albert V.; Kasianowicz, John J.; Suehle, John S.; Li, Qiliang

    2017-10-01

    Novel nanofluidic chemical cells based on self-assembled solid-state SiO2 nanotubes on silicon-on-insulator (SOI) substrate have been successfully fabricated and characterized. The vertical SiO2 nanotubes with a smooth cavity are built from Si nanowires which were epitaxially grown on the SOI substrate. The nanotubes have rigid, dry-oxidized SiO2 walls with precisely controlled nanotube inner diameter, which is very attractive for chemical-/bio-sensing applications. No dispersion/aligning procedures were involved in the nanotube fabrication and integration by using this technology, enabling a clean and smooth chemical cell. Such a robust and well-controlled nanotube is an excellent case of developing functional nanomaterials by leveraging the strength of top-down lithography and the unique advantage of bottom-up growth. These solid, smooth, clean SiO2 nanotubes and nanofluidic devices are very encouraging and attractive in future bio-medical applications, such as single molecule sensing and DNA sequencing.

  8. Cryo-chemical decellularization of the whole liver for mesenchymal stem cells-based functional hepatic tissue engineering.

    Science.gov (United States)

    Jiang, Wei-Cheng; Cheng, Yu-Hao; Yen, Meng-Hua; Chang, Yin; Yang, Vincent W; Lee, Oscar K

    2014-04-01

    Liver transplantation is the ultimate treatment for severe hepatic failure to date. However, the limited supply of donor organs has severely hampered this treatment. So far, great potentials of using mesenchymal stem cells (MSCs) to replenish the hepatic cell population have been shown; nevertheless, there still is a lack of an optimal three-dimensional scaffold for generation of well-transplantable hepatic tissues. In this study, we utilized a cryo-chemical decellularization method which combines physical and chemical approach to generate acellular liver scaffolds (ALS) from the whole liver. The produced ALS provides a biomimetic three-dimensional environment to support hepatic differentiation of MSCs, evidenced by expression of hepatic-associated genes and marker protein, glycogen storage, albumin secretion, and urea production. It is also found that hepatic differentiation of MSCs within the ALS is much more efficient than two-dimensional culture in vitro. Importantly, the hepatic-like tissues (HLT) generated by repopulating ALS with MSCs are able to act as functional grafts and rescue lethal hepatic failure after transplantation in vivo. In summary, the cryo-chemical method used in this study is suitable for decellularization of liver and create acellular scaffolds that can support hepatic differentiation of MSCs and be used to fabricate functional tissue-engineered liver constructs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. A quantum-chemical perspective into low optical-gap polymers for highly-efficient organic solar cells

    KAUST Repository

    Risko, Chad

    2011-03-15

    The recent and rapid enhancement in power conversion efficiencies of organic-based, bulk heterojunction solar cells has been a consequence of both improved materials design and better understanding of the underlying physical processes involved in photocurrent generation. In this Perspective, we first present an overview of the application of quantum-chemical techniques to study the intrinsic material properties and molecular- and nano-scale processes involved in device operation. In the second part, these quantum-chemical tools are applied to an oligomer-based study on a collection of donor-acceptor copolymers that have been used in the highest-efficiency solar cell devices reported to date. The quantum-chemical results are found to be in good agreement with the empirical data related to the electronic and optical properties. In particular, they provide insight into the natures of the electronic excitations responsible for the near-infrared/visible absorption profiles, as well as into the energetics of the low-lying singlet and triplet states. These results lead to a better understanding of the inherent differences among the materials, and highlight the usefulness of quantum chemistry as an instrument for material design. Importantly, the results also point to the need to continue the development of integrated, multi scale modeling approaches to provide a thorough understanding of the materials properties. © The Royal Society of Chemistry 2011.

  10. Chemical inhibition of cell recovery after irradiation with sparsely and densely ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Evastratova, Ekaterina S.; Petin, Vladislav [A. Tsyb Medical Radiological Research Centre-branch of the National Medical Research Radiological Centre of the Ministry of Health of the Russian Federation, Obninsk (Russian Federation); Kim, Jin Hong; Kim, Jin Kyu [Korea Atomic Energy Research Institute, Advanced Radiation Technology Institute (ARTI), Jeongeup (Korea, Republic of); Lim, Youg Khi [Dept. of Radiological Science, Gachon University, Incheon (Korea, Republic of)

    2017-02-15

    The dependence of cell survival on exposure dose and the duration of the liquid holding recovery (LHR) was obtained for diploid yeast cells irradiated with ionizing radiation of different linear energy transfer (LET) and recovering from radiation damage without and with various concentrations of cisplatin - the most widely used anticancer drug. The ability of yeast cells to recover from radiation damage was less effective after cell exposure to high-LET radiation, when cells were irradiated without drug. The increase in cisplatin concentration resulted in the disappearance of this difference whereas the fraction of irreversible damage was permanently enlarged independently of radiation quality. The probability of cell recovery was shown to be constant for various conditions of irradiation and recovery. A new mechanism of cisplatin action was suggested according with which the inhibition of cell recovery after exposure to ionizing radiations was completely explained by the production of irreversible damage.

  11. Chemical Modification of n-Type-Material Naphthalene Diimide on ITO for Efficient and Stable Inverted Polymer Solar Cells.

    Science.gov (United States)

    Li, Zhendong; Liu, Yanfeng; Zhang, Kaicheng; Wang, Zhaowei; Huang, Peng; Li, Dahua; Zhou, Yi; Song, Bo

    2017-09-05

    To provide orthogonal solvent processable surface modification and improve the device stability of bulk-heterojunction polymer solar cells (PSCs), n-type semiconducting material naphthalene diimide (NDI) was chemically introduced onto the ITO surface as a cathode interlayer (CIL) using 3-bromopropyltrimethoxysilane (BrTMS) as a coupling agent. After modification, the work function of ITO can be decreased from 4.70 to 4.23 eV. The modified ITO cathode was applied in inverted PSCs based on PTB7-Th:PC71BM. With the CIL modification, a champion power conversion efficiency (PCE) of 5.87% was achieved, showing a dramatic improvement compared to that of devices (PCE = 3.58%) without CIL. More importantly, with these chemical bonded interlayers, the stability of inverted PSCs was greatly enhanced. The improved PCE and stability can be attributed to the increased open-circuit voltage and the formation of robust chemical bonds in NDI-TMS films, respectively. This study demonstrated that chemical modification of ITO with n-type semiconducting materials provides an avenue for not only solving the solvent orthogonal problem but also improving the device performance in terms of the PCE and the stability.

  12. Peroxisome Proliferator-Activated Receptors in Regulation of Cytochromes P450: New Way to Overcome Multidrug Resistance?

    OpenAIRE

    Katerina Cizkova; Anna Konieczna; Bela Erdosova; Radka Lichnovska; Jiri Ehrmann

    2012-01-01

    Embryonic and tumour cells are able to protect themselves against various harmful compounds. In human pathology, this phenomenon exists in the form of multidrug resistance (MDR) that significantly deteriorates success of anticancer treatment. Cytochromes P450 (CYPs) play one of the key roles in the xenobiotic metabolism. CYP expression could contribute to resistance of cancer cells to chemotherapy. CYP epoxygenases (CYP2C and CYP2J) metabolize about 20% of clinically important drugs. Besides ...

  13. Inducible bilirubin oxidase: A novel function for the mouse cytochrome P450 2A5

    Energy Technology Data Exchange (ETDEWEB)

    Abu-Bakar, A' edah, E-mail: a.abubakar@uq.edu.au [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia); Arthur, Dionne Maioha [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia); Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, Adelaide (Australia); Aganovic, Simona [Department of Pharmaceutical Biosciences, Uppsala University, Biomedical Centre, Box 578, S-751 23 Uppsala (Sweden); Ng, Jack C. [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia); Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, Adelaide (Australia); Lang, Matti A. [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia); Department of Pharmaceutical Biosciences, Uppsala University, Biomedical Centre, Box 578, S-751 23 Uppsala (Sweden)

    2011-11-15

    We have previously shown that bilirubin (BR), a breakdown product of haem, is a strong inhibitor and a high affinity substrate of the mouse cytochrome P450 2A5 (CYP2A5). The antioxidant BR, which is cytotoxic at high concentrations, is potentially useful in cellular protection against oxygen radicals if its intracellular levels can be strictly controlled. The mechanisms that regulate cellular BR levels are still obscure. In this paper we provide preliminary evidence for a novel function of CYP2A5 as hepatic 'BR oxidase'. A high-performance liquid chromatography/electrospray ionisation mass spectrometry screening showed that recombinant yeast microsomes expressing the CYP2A5 oxidise BR to biliverdin, as the main metabolite, and to three other smaller products with m/z values of 301, 315 and 333. The metabolic profile is significantly different from that of chemical oxidation of BR. In chemical oxidation the smaller products were the main metabolites. This suggests that the enzymatic reaction is selective, towards biliverdin production. Bilirubin treatment of primary hepatocytes increased the CYP2A5 protein and activity levels with no effect on the corresponding mRNA. Co-treatment with cycloheximide (CHX), a protein synthesis inhibitor, resulted in increased half-life of the CYP2A5 compared to cells treated only with CHX. Collectively, the observations suggest that the CYP2A5 is potentially an inducible 'BR oxidase' where BR may accelerate its own metabolism through stabilization of the CYP2A5 protein. It is possible that this metabolic pathway is potentially part of the machinery controlling intracellular BR levels in transient oxidative stress situations, in which high amounts of BR are produced. -- Highlights: Black-Right-Pointing-Pointer CYP2A5 metabolizes bilirubin to biliverdin and dipyrroles. Black-Right-Pointing-Pointer Bilirubin increased the hepatic CYP2A5 protein and activity levels. Black-Right-Pointing-Pointer Bilirubin does not

  14. c-Type cytochrome-dependent formation of U(IV nanoparticles by Shewanella oneidensis.

    Directory of Open Access Journals (Sweden)

    Matthew J Marshall

    2006-09-01

    Full Text Available Modern approaches for bioremediation of radionuclide contaminated environments are based on the ability of microorganisms to effectively catalyze changes in the oxidation states of metals that in turn influence their solubility. Although microbial metal reduction has been identified as an effective means for immobilizing highly-soluble uranium(VI complexes in situ, the biomolecular mechanisms of U(VI reduction are not well understood. Here, we show that c-type cytochromes of a dissimilatory metal-reducing bacterium, Shewanella oneidensis MR-1, are essential for the reduction of U(VI and formation of extracellular UO(2 nanoparticles. In particular, the outer membrane (OM decaheme cytochrome MtrC (metal reduction, previously implicated in Mn(IV and Fe(III reduction, directly transferred electrons to U(VI. Additionally, deletions of mtrC and/or omcA significantly affected the in vivo U(VI reduction rate relative to wild-type MR-1. Similar to the wild-type, the mutants accumulated UO(2 nanoparticles extracellularly to high densities in association with an extracellular polymeric substance (EPS. In wild-type cells, this UO(2-EPS matrix exhibited glycocalyx-like properties and contained multiple elements of the OM, polysaccharide, and heme-containing proteins. Using a novel combination of methods including synchrotron-based X-ray fluorescence microscopy and high-resolution immune-electron microscopy, we demonstrate a close association of the extracellular UO(2 nanoparticles with MtrC and OmcA (outer membrane cytochrome. This is the first study to our knowledge to directly localize the OM-associated cytochromes with EPS, which contains biogenic UO(2 nanoparticles. In the environment, such association of UO(2 nanoparticles with biopolymers may exert a strong influence on subsequent behavior including susceptibility to oxidation by O(2 or transport in soils and sediments.

  15. Rapid Induction of Cerebral Organoids From Human Induced Pluripotent Stem Cells Using a Chemically Defined Hydrogel and Defined Cell Culture Medium.

    Science.gov (United States)

    Lindborg, Beth A; Brekke, John H; Vegoe, Amanda L; Ulrich, Connor B; Haider, Kerri T; Subramaniam, Sandhya; Venhuizen, Scott L; Eide, Cindy R; Orchard, Paul J; Chen, Weili; Wang, Qi; Pelaez, Francisco; Scott, Carolyn M; Kokkoli, Efrosini; Keirstead, Susan A; Dutton, James R; Tolar, Jakub; O'Brien, Timothy D

    2016-07-01

    Tissue organoids are a promising technology that may accelerate development of the societal and NIH mandate for precision medicine. Here we describe a robust and simple method for generating cerebral organoids (cOrgs) from human pluripotent stem cells by using a chemically defined hydrogel material and chemically defined culture medium. By using no additional neural induction components, cOrgs appeared on the hydrogel surface within 10-14 days, and under static culture conditions, they attained sizes up to 3 mm in greatest dimension by day 28. Histologically, the organoids showed neural rosette and neural tube-like structures and evidence of early corticogenesis. Immunostaining and quantitative reverse-transcription polymerase chain reaction demonstrated protein and gene expression representative of forebrain, midbrain, and hindbrain development. Physiologic studies showed responses to glutamate and depolarization in many cells, consistent with neural behavior. The method of cerebral organoid generation described here facilitates access to this technology, enables scalable applications, and provides a potential pathway to translational applications where defined components are desirable. Tissue organoids are a promising technology with many potential applications, such as pharmaceutical screens and development of in vitro disease models, particularly for human polygenic conditions where animal models are insufficient. This work describes a robust and simple method for generating cerebral organoids from human induced pluripotent stem cells by using a chemically defined hydrogel material and chemically defined culture medium. This method, by virtue of its simplicity and use of defined materials, greatly facilitates access to cerebral organoid technology, enables scalable applications, and provides a potential pathway to translational applications where defined components are desirable. ©AlphaMed Press.

  16. Using the peptide BP100 as a cell-penetrating tool for the chemical engineering of actin filaments within living plant cells.

    Science.gov (United States)

    Eggenberger, Kai; Mink, Christian; Wadhwani, Parvesh; Ulrich, Anne S; Nick, Peter

    2011-01-03

    The delivery of externally applied macromolecules or nanoparticles into living cells still represents a critically limiting step before the full capabilities of chemical engineering can be explored. Molecular transporters such as cell-penetrating peptides, peptoids, and other mimetics can be used to carry cargo across the cellular membrane, but it is still difficult to find suitable sequences that operate efficiently for any particular type of cell. Here we report that BP100 (KKLFKKILKYL-amide), originally designed as an antimicrobial peptide against plant pathogens, can be employed as a fast and efficient cell-penetrating agent to transport fluorescent test cargoes into the cytosol of walled plant cells. The uptake of BP100 proceeds slightly more slowly than the endocytosis of fluorescent dextranes, but BP100 accumulates more efficiently and to much higher levels (by an order of magnitude). The entry of BP100 can be efficiently blocked by latrunculin B; this suggests that actin filaments are essential to the uptake mechanism. To test whether this novel transporter can also be used to deliver functional cargoes, we designed a fusion construct of BP100 with the actin-binding Lifeact peptide (MGVADLIKKFESISKEE). We demonstrated that the short BP100 could transport the attached 17-residue sequence quickly and efficiently into tobacco cells. The Lifeact construct retained its functionality as it successfully labeled the actin bundles that tether the nucleus in the cell center.

  17. Cell patterns emerge from coupled chemical and physical fields with cell proliferation dynamics: the Arabidopsis thaliana root as a study system.

    Directory of Open Access Journals (Sweden)

    Rafael A Barrio

    Full Text Available A central issue in developmental biology is to uncover the mechanisms by which stem cells maintain their capacity to regenerate, yet at the same time produce daughter cells that differentiate and attain their ultimate fate as a functional part of a tissue or an organ. In this paper we propose that, during development, cells within growing organs obtain positional information from a macroscopic physical field that is produced in space while cells are proliferating. This dynamical interaction triggers and responds to chemical and genetic processes that are specific to each biological system. We chose the root apical meristem of Arabidopsis thaliana to develop our dynamical model because this system is well studied at the molecular, genetic and cellular levels and has the key traits of multicellular stem-cell niches. We built a dynamical model that couples fundamental molecular mechanisms of the cell cycle to a tension physical field and to auxin dynamics, both of which are known to play a role in root development. We perform extensive numerical calculations that allow for quantitative comparison with experimental measurements that consider the cellular patterns at the root tip. Our model recovers, as an emergent pattern, the transition from proliferative to transition and elongation domains, characteristic of stem-cell niches in multicellular organisms. In addition, we successfully predict altered cellular patterns that are expected under various applied auxin treatments or modified physical growth conditions. Our modeling platform may be extended to explicitly consider gene regulatory networks or to treat other developmental systems.

  18. Chemical modification allows phallotoxins and amatoxins to be used as tools in cell biology.

    Science.gov (United States)

    Anderl, Jan; Echner, Hartmut; Faulstich, Heinz

    2012-01-01

    Phallotoxins inhibit the dynamics of microfilaments in cells and lead to apoptosis. Due to poor cellular uptake these effects cannot be studied in live cells, even at millimolar toxin concentrations, nor can phalloidin be used for the elimination of tumor cells. Uptake is greatly enhanced by conjugation of phallotoxins to either lipophilic or polycationic moieties, such as oleic acid, polylysine, or Tat-peptide. These conjugates were lethally toxic for cells, e.g., mouse fibroblasts or Jurkat leukemia cells, in the micromolar range. Uptake into cells starts with the attachment of the toxin conjugates to the plasma membrane, followed by endocytosis and, in most cases, cleavage of the toxin from the carrier. Interestingly, the internalization rate of phalloidin into cells was also significantly increased by the fluorescent moiety tetramethylrhodaminyl, as well as by high molecular weight methoxy-polyethyleneglycol, two compounds unknown so far for their uptake-mediating activity. Conjugation to carriers as investigated in this work will allow the use of phallotoxins in experimental cell biology and possibly in tumor therapy. The findings obtained with phallotoxins could be applied also to the family of amatoxins, where α-amanitin, for example, when conjugated to oleic acid was more than 100-fold more toxic for cells than the native toxin. This suggests the possibility of a more general use of the moieties examined here to enhance the uptake of hydrophilic peptides, or drugs, into live cells.

  19. Chemical modification allows phallotoxins and amatoxins to be used as tools in cell biology

    Directory of Open Access Journals (Sweden)

    Jan Anderl

    2012-11-01

    Full Text Available Phallotoxins inhibit the dynamics of microfilaments in cells and lead to apoptosis. Due to poor cellular uptake these effects cannot be studied in live cells, even at millimolar toxin concentrations, nor can phalloidin be used for the elimination of tumor cells. Uptake is greatly enhanced by conjugation of phallotoxins to either lipophilic or polycationic moieties, such as oleic acid, polylysine, or Tat-peptide. These conjugates were lethally toxic for cells, e.g., mouse fibroblasts or Jurkat leukemia cells, in the micromolar range. Uptake into cells starts with the attachment of the toxin conjugates to the plasma membrane, followed by endocytosis and, in most cases, cleavage of the toxin from the carrier. Interestingly, the internalization rate of phalloidin into cells was also significantly increased by the fluorescent moiety tetramethylrhodaminyl, as well as by high molecular weight methoxy-polyethyleneglycol, two compounds unknown so far for their uptake-mediating activity. Conjugation to carriers as investigated in this work will allow the use of phallotoxins in experimental cell biology and possibly in tumor therapy. The findings obtained with phallotoxins could be applied also to the family of amatoxins, where α-amanitin, for example, when conjugated to oleic acid was more than 100-fold more toxic for cells than the native toxin. This suggests the possibility of a more general use of the moieties examined here to enhance the uptake of hydrophilic peptides, or drugs, into live cells.

  20. Development of the microbial electrolysis desalination and chemical-production cell for desalination as well as acid and alkali productions.

    Science.gov (United States)

    Chen, Shanshan; Liu, Guangli; Zhang, Renduo; Qin, Bangyu; Luo, Yong

    2012-02-21

    By combining the microbial electrolysis cell and the microbial desalination cell, the microbial electrolysis desalination cell (MEDC) becomes a novel device to desalinate salty water. However, several factors, such as sharp pH decrease and Cl(-) accumulation in the anode chamber, limit the MEDC development. In this study, a microbial electrolysis desalination and chemical-production cell (MEDCC) was developed with four chambers using a bipolar membrane. Results showed that the pH in the anode chamber of the MEDCC always remained near 7.0, which greatly enhanced the microbial activities in the cell. With applied voltages of 0.3-1.0 V, 62%-97% of Coulombic efficiencies were achieved from the MEDCC, which were 1.5-2.0 times of those from the MEDC. With 10 mL of 10 g/L NaCl in the desalination chamber, desalination rates of the MEDCC reached 46%-86% within 18 h. Another unique feature of the MEDCC was the simultaneous production of HCl and NaOH in the cell. With 1.0 V applied voltage, the pH values at 18 h in the acid-production chamber and cathode chamber were 0.68 and 12.9, respectively. With the MEDCC, the problem with large pH changes in the anode chamber was resolved, and products of the acid and alkali were obtained.

  1. Chemical functionalization of graphene to augment stem cell osteogenesis and inhibit biofilm formation on polymer composites for orthopedic applications.

    Science.gov (United States)

    Kumar, Sachin; Raj, Shammy; Kolanthai, Elayaraja; Sood, A K; Sampath, S; Chatterjee, Kaushik

    2015-02-11

    Toward designing the next generation of resorbable biomaterials for orthopedic applications, we studied poly(ε-caprolactone) (PCL) composites containing graphene. The role, if any, of the functionalization of graphene on mechanical properties, stem cell response, and biofilm formation was systematically evaluated. PCL composites of graphene oxide (GO), reduced GO (RGO), and amine-functionalized GO (AGO) were prepared at different filler contents (1%, 3%, and 5%). Although the addition of the nanoparticles to PCL markedly increased the storage modulus, this increase was largest for GO followed by AGO and RGO. In vitro cell studies revealed that the AGO and GO particles significantly increased human mesenchymal stem cell proliferation. AGO was most effective in augmenting stem cell osteogenesis leading to mineralization. Bacterial studies revealed that interaction with functionalized GO induced bacterial cell death because of membrane damage, which was further accentuated by amine groups in AGO. As a result, AGO composites were best at inhibiting biofilm formation. The synergistic effect of oxygen containing functional groups and amine groups on AGO imparts the optimal combination of improved modulus, favorable stem cell response, and biofilm inhibition in AGO-reinforced composites desired for orthopedic applications. This work elucidates the importance of chemical functionalization of graphene in polymer composites for biomedical applications.

  2. Silicification process in diatom algae using different silicon chemical sources: Colloidal silicic acid interactions at cell surface.

    Science.gov (United States)

    Casabianca, Silvia; Penna, Antonella; Capellacci, Samuela; Cangiotti, Michela; Ottaviani, Maria Francesca

    2018-01-01

    The silicon transport and use inside cells are key processes for understanding how diatoms metabolize this element in the silica biogenic cycle in the ocean. A spin-probe electron paramagnetic resonance (EPR) study over time helped to investigate the interacting properties and the internalization mechanisms of silicic acid from different silicon sources into the cells. Diatom cells were grown in media containing biogenic amorphous substrates, such as diatomaceous earth and sponge spicules, and crystalline sodium metasilicate. It was found that the amorphous biogenic silicon slowed down the internalization process probably due to formation of colloidal particles at the cell surface after silicic acid condensation. Weaker interactions occurred with sponge spicules silicon source if compared to the other sources. The EPR results were explained by analyzing transcript level changes of silicon transporters (SITs) and silaffins (SILs) in synchronized Thalassiosira pseudonana cultures over time. The results indicated that the transport role of SITs is minor for silicic acid from both biogenic and crystalline substrates, and the role of SIT3 is linked to the transport of silicon inside the cells, mainly in the presence of sponge spicules. SIL3 transcripts were expressed in the presence of all silicon sources, while SIL1 transcripts only with sponge spicules. The data suggest that the transport of silicic acid from various silicon sources in diatoms is based on different physico-chemical interactions with the cell surface. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. The presence of multiple c-type cytochromes at the surface of the methanotrophic bacterium Methylococcus capsulatus (Bath) is regulated by copper.

    Science.gov (United States)

    Karlsen, O A; Lillehaug, J R; Jensen, H B

    2008-10-01

    Identification of surface proteins is essential to understand bacterial communication with its environment. Analysis of the surface-associated proteins of Methylococcus capsulatus (Bath) revealed a highly dynamic structure responding closely to the availability of copper in the medium in the range from approximately 0 to 10 microM. Several c-type cytochromes, including three novel multihaem proteins, are present at the cellular surface, a feature that is otherwise a peculiarity of dissimilatory metal-reducing bacteria. At low copper concentrations, the cytochrome c(553o) and the cytochrome c(553o) family protein, encoded by the MCA0421 and MCA0423 genes, respectively, are major constituents of the surfaceome and show a fine-tuned copper-dependent regulation of expression. Two novel members of the cytochrome c(553o) family were identified: MCA0338 was abundant between 5 and 10 microM copper, while MCA2259 was detected only in the surface fraction obtained from approximately 0 microM copper cultures. The presence at the bacterial surface of several c-type cytochromes, generally involved in energy transduction, indicates strongly that redox processes take place at the bacterial surface. Due to the unique role of copper in the biology of M. capsulatus (Bath), it appears that c-type cytochromes have essential functions in copper homeostasis allowing the cells to adapt to varying copper exposure.