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Sample records for catechol estrogen adducts

  1. Inhibition of catechol-O-methyltransferase increases estrogen-DNA adduct formation

    PubMed Central

    Zahid, Muhammad; Saeed, Muhammad; Lu, Fang; Gaikwad, Nilesh; Rogan, Eleanor; Cavalieri, Ercole

    2007-01-01

    The association found between breast cancer development and prolonged exposure to estrogens suggests that this hormone is of etiologic importance in the causation of the disease. Studies on estrogen metabolism, formation of DNA adducts, carcinogenicity, cell transformation and mutagenicity have led to the hypothesis that reaction of certain estrogen metabolites, predominantly catechol estrogen-3,4-quinones, with DNA forms depurinating adducts [4-OHE1(E2)-1-N3Ade and 4-OHE1(E2)-1-N7Gua]. These adducts cause mutations leading to the initiation of breast cancer. Catechol-O-methyltransferase (COMT) is considered an important enzyme that protects cells from the genotoxicity and cytotoxicity of catechol estrogens, by preventing their conversion to quinones. The goal of the present study was to investigate the effect of COMT inhibition on the formation of depurinating estrogen-DNA adducts. Immortalized human breast epithelial MCF-10F cells were treated with 4-OHE2 (0.2 or 0.5 μM) for 24 h at 120, 168, 216, and 264 h post-plating or one time at 1–30 μM 4-OHE2 with or without the presence of COMT inhibitor (Ro41-0960). The culture media were collected at each point, extracted by solid-phase extraction and analyzed by HPLC connected with a multichannel electrochemical detector. The results demonstrate that MCF-10F cells oxidize 4-OHE2 to E1(E2)-3,4-Q, which react with DNA to form the depurinating N3Ade and N7Gua adducts. The COMT inhibitor Ro41-0960 blocked the methoxylation of catechol estrogens, with concomitant 3–4 fold increases in the levels of the depurinating adducts. Thus, low activity of COMT leads to higher levels of depurinating estrogen-DNA adducts that can induce mutations and initiate cancer. PMID:17964424

  2. Estrogen metabolism and formation of estrogen-DNA adducts in estradiol-treated MCF-10F cells. The effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin induction and catechol-O-methyltransferase inhibition

    PubMed Central

    Lu, Fang; Zahid, Muhammad; Saeed, Muhammad; Cavalieri, Ercole L.; Rogan, Eleanor G.

    2007-01-01

    Formation of estrogen metabolites that react with DNA is thought to be a mechanism of cancer initiation by estrogens. The estrogens estrone (E1) and estradiol (E2) can form catechol estrogen (CE) metabolites, catechol estrogen quinones [E1(E2)-3,4-Q], which react with DNA to form predominantly depurinating adducts. This may lead to mutations that initiate cancer. Catechol-O-methyltransferase (COMT) catalyzes an inactivation (protective) pathway for CE. This study investigated the effect of inhibiting COMT activity on the levels of depurinating 4-OHE1(E2)-1-N3Ade and 4-OHE1(E2)-1-N7Gua adducts in human breast epithelial cells. MCF-10F cells were treated with TCDD, a cytochrome P450 inducer, then with E2 and Ro41−0960, a COMT inhibitor. Estrogen metabolites and depurinating DNA adducts in culture medium were analyzed by HPLC with electrochemical detection. Pretreatment of cells with TCDD increased E2 metabolism to 4-OHE1(E2) and 4-OCH3E1(E2). Inclusion of Ro41−0960 and E2 in the medium blocked formation of methoxyCE, and depurinating adducts were observed. With Ro41−0960, more adducts were detected in MCF-10F cells exposed to 1 μM E2, whereas without the inhibitor, no increases in adducts were detected with E2 ≤10 μM. We conclude that low COMT activity and increased formation of depurinating adducts can be critical factors leading to initiation of breast cancer. PMID:17582757

  3. Depurinating estrogen-DNA adducts, generators of cancer initiation: their minimization leads to cancer prevention.

    PubMed

    Cavalieri, Ercole L; Rogan, Eleanor G

    2016-03-01

    Estrogens can initiate cancer by reacting with DNA. Specific metabolites of endogenous estrogens, the catechol estrogen-3,4-quinones, react with DNA to form depurinating estrogen-DNA adducts. Loss of these adducts leaves apurinic sites in the DNA, generating mutations that can lead to the initiation of cancer. A variety of endogenous and exogenous factors can disrupt estrogen homeostasis, which is the normal balance between estrogen activating and protective enzymes. In fact, if estrogen metabolism becomes unbalanced and generates excessive catechol estrogen 3,4-quinones, formation of depurinating estrogen-DNA adducts increases and the risk of initiating cancer is greater. The levels of depurinating estrogen-DNA adducts are high in women diagnosed with breast cancer and those at high risk for the disease. High levels of depurinating estrogen-DNA adducts before the presence of breast cancer indicates that adduct formation is a critical factor in breast cancer initiation. Women with thyroid or ovarian cancer also have high levels of estrogen-DNA adducts, as do men with prostate cancer or non-Hodgkin lymphoma. Depurinating estrogen-DNA adducts are initiators of many prevalent types of human cancer. These findings and other discoveries led to the recognition that reducing the levels of estrogen-DNA adducts could prevent the initiation of human cancer. The dietary supplements N-acetylcysteine and resveratrol inhibit formation of estrogen-DNA adducts in cultured human breast cells and in women. These results suggest that the two supplements offer an approach to reducing the risk of developing various prevalent types of human cancer. Graphical abstract Major metabolic pathway in cancer initiation by estrogens. PMID:26979321

  4. Urinary biomarkers suggest that estrogen-DNA adducts may play a role in the aetiology of non-Hodgkin lymphoma

    PubMed Central

    Gaikwad, Nilesh W.; Yang, Li; Weisenburger, Dennis D.; Vose, Julie; Beseler, Cheryl; Rogan, Eleanor G.; Cavalieri, Ercole L.

    2015-01-01

    A variety of evidence suggests that estrogens may induce non-Hodgkin lymphoma (NHL). The reaction of catechol estrogen quinones with DNA to form depurinating estrogen-DNA adducts is hypothesized to initiate this process. These adducts are released from DNA, shed from cells into the bloodstream and excreted in urine. The aim of this study was to determine whether or not the depurinating estrogen-DNA adducts might be involved in the aetiology of human NHL. Estrogen metabolites, conjugates and depurinating DNA adducts were identified and quantified in spot urine samples from 15 men with NHL and 30 healthy control men by using ultraperformance liquid chromatography/tandem mass spectrometry. The levels of estrogen-DNA adducts were significantly higher in the men with NHL than in the healthy control men. Thus, formation of estrogen-DNA adducts may play a critical role in the aetiology of NHL, and these adducts could be potential biomarkers of NHL risk. PMID:19863189

  5. Catechol estrogens: presence in brain and endocrine tissues.

    PubMed

    Paul, S M; Axelrod, J

    1977-08-12

    Catechol estrogens have been identified and measured in rat brain and various endocrine tissues with the use of a sensitive radioenzymatic assay. The specificity of this assay was confirmed by thin-layer chromatography and mass spectral analysis of the reaction products. The concentration of catechol estrogens in the hypothalamus and pituitary are at least ten times higher than reported previously for the parent estrogens. Catechol estrogens have potent endocrine effects and, because of their normal occurrence in the hypothalamic-pituitary axis, they have an important role in neuroendocrine regulation.

  6. Cytochrome P450 isoforms catalyze formation of catechol estrogen quinones that react with DNA.

    PubMed

    Zhang, Yan; Gaikwad, Nilesh W; Olson, Kevin; Zahid, Muhammad; Cavalieri, Ercole L; Rogan, Eleanor G

    2007-07-01

    Accumulating evidence suggests that specific metabolites of estrogens, namely, catechol estrogen quinones, react with DNA to form adducts and generate apurinic sites, which can lead to the mutations that induce breast cancer. Oxidation of estradiol (E(2)) produces 2 catechol estrogens, 4-hydroxyestradiol (4-OHE(2)) and 2-OHE(2) among the major metabolites. These, in turn, are oxidized to the quinones, E(2)-3,4-quinone (E(2)-3,4-Q) and E(2)-2,3-Q, which can react with DNA. Oxidation of E(2) to 2-OHE(2) is mainly catalyzed by cytochrome P450 (CYP) 1A1, and CYP3A4, whereas oxidation of E(2) to 4-OHE(2) in extrahepatic tissues is mainly catalyzed by CYP1B1 as well as some CYP3As. The potential involvement of CYP isoforms in the further oxidation of catechols to semiquinones and quinones has, however, not been investigated in detail. In this project, to identify the potential function of various CYPs in oxidizing catechol estrogens to quinones, we used different recombinant human CYP isoforms, namely, CYP1A1, CYP1B1, and CYP3A4, with the scope of oxidizing the catechol estrogens 2-OHE(2) and 4-OHE(2) to their respective estrogen quinones, which then reacted with DNA. The depurinating adducts 2-OHE(2)-6-N3Ade, 4-OHE(2)-1-N3Ade, and 4-OHE(2)-1-N7Gua were observed in the respective reaction systems by ultraperformance liquid chromatography/tandem mass spectrometry. Furthermore, more than 100-fold higher levels of estrogen-glutathione (GSH) conjugates were detected in the reactions. Glutathione conjugates were observed, in much smaller amounts, when control microsomes were used. Depurinating adducts, as well as GSH conjugates, were obtained when E(2)-3,4-Q was incubated with CYP1B1 or control microsomes in a 30-minute reaction, further demonstrating that GSH is present in these recombinant enzyme preparations. These experiments demonstrated that CYP1A1, CYP1B1, and CYP3A4 are able to oxidize catechol estrogens to their respective quinones, which can further react with GSH

  7. Synthesis of catechol estrogens by human uterus and leiomyoma

    SciTech Connect

    Reddy, V.V.; Hanjani, P.; Rajan, R.

    1981-02-01

    Homogenates of human endometrial, myometrial and leiomyoma tissues were incubated with (2,4,6,7-/sub 3/H)-estradiol and tritiated catechol estrogens were isolated and identified. Though 2- and 4-hydroxylations were about the same in endometrium, 4-hydroxylation was two to four fold higher than 2-hydroxylation in myometrium and leiomyoma. However, endometrium showed greater capacity to form both 2- and 4-hydroxyestrogens than the other two tissues. Both 2- and 4-hydroxylations were significantly less than in myometrium. In view of the reports indicating that inhibitors of catechol 0-methyl transferase (COMT) might act as antineoplastic agents due to their interference with t-RNA methylases and since catechol estrogens inhibit COMT, the present results suggest that endogenous synthesis of catechol estrogens may play an important role in the pathophysiology of uterine leiomyoma.

  8. Prevention of estrogen-DNA adduct formation in MCF-10F cells by resveratrol

    PubMed Central

    Zahid, Muhammad; Gaikwad, Nilesh W.; Ali, Mohamed F.; Lu, Fang; Saeed, Muhammad; Yang, Li; Rogan, Eleanor G.; Cavalieri, Ercole L.

    2008-01-01

    Resveratrol (Resv), a natural occurring phytolexin present in grapes and other foods, possesses chemopreventive effects revealed by its striking modulation of diverse cellular events associated with tumor initiation, promotion and progression. Catechol estrogens generated in the metabolism of estrogens are oxidized to catechol quinones that react with DNA to form predominantly depurinating estrogen-DNA adducts. This event can generate the mutations responsible for cancer initiation. In this regard, Resv acts as both an antioxidant and an inducer of the phase II enzyme NAD(P)H:quinone oxidoreductase 1 (NQO1). In this report, we present the effects of Resv on the metabolism of estrogens in normal breast epithelial cells (MCF-10F) treated with 4-hydroxyestradiol (4-OHE2) or estradiol-3,4-quinone (E2-3,4-Q). Resv induced NQO1 in a dose- and time-dependent manner, but did not affect the expression of catechol-O-methyltransferase. Ultraperformance liquid chromatography/tandem mass spectrometry was used to determine the effects of Resv on estrogen metabolism. Preincubation of the cells with Resv for 48 h decreased the formation of depurinating estrogen-DNA adducts from 4-OHE2 or E2-3,4-Q and increased formation of methoxycatechol estrogens. When Resv was also present with the 4-OHE2 or E2-3,4-Q, even greater increases in methoxycatechol estrogens were observed, and the DNA adducts were undetectable. We conclude that Resv can protect breast cells from carcinogenic estrogen metabolites, suggesting that it could be used in breast cancer prevention. PMID:18423413

  9. Site-specific covalent modifications of human insulin by catechol estrogens: Reactivity and induced structural and functional changes

    NASA Astrophysics Data System (ADS)

    Ku, Ming-Chun; Fang, Chieh-Ming; Cheng, Juei-Tang; Liang, Huei-Chen; Wang, Tzu-Fan; Wu, Chih-Hsing; Chen, Chiao-Chen; Tai, Jung-Hsiang; Chen, Shu-Hui

    2016-06-01

    Proteins, covalently modified by catechol estrogens (CEs), were identified recently from the blood serum of diabetic patients and referred to as estrogenized proteins. Estrogenization of circulating insulin may occur and affect its molecular functioning. Here, the chemical reactivity of CEs towards specific amino acid residues of proteins and the structural and functional changes induced by the estrogenization of insulin were studied using cyclic voltammetry, liquid chromatography-mass spectrometry, circular dichroism spectroscopy, molecular modeling, and bioassays. Our results indicate that CEs, namely, 2- and 4-hydroxyl estrogens, were thermodynamically and kinetically more reactive than the catechol moiety. Upon co-incubation, intact insulin formed a substantial number of adducts with one or multiple CEs via covalent conjugation at its Cys 7 in the A or B chain, as well as at His10 or Lys29 in the B chain. Such conjugation was coupled with the cleavage of inter-chain disulfide linkages. Estrogenization on these sites may block the receptor-binding pockets of insulin. Insulin signaling and glucose uptake levels were lower in MCF-7 cells treated with modified insulin than in cells treated with native insulin. Taken together, our findings demonstrate that insulin molecules are susceptible to active estrogenization, and that such modification may alter the action of insulin.

  10. Site-specific covalent modifications of human insulin by catechol estrogens: Reactivity and induced structural and functional changes

    PubMed Central

    Ku, Ming-Chun; Fang, Chieh-Ming; Cheng, Juei-Tang; Liang, Huei-Chen; Wang, Tzu-Fan; Wu, Chih-Hsing; Chen, Chiao-Chen; Tai, Jung-Hsiang; Chen, Shu-Hui

    2016-01-01

    Proteins, covalently modified by catechol estrogens (CEs), were identified recently from the blood serum of diabetic patients and referred to as estrogenized proteins. Estrogenization of circulating insulin may occur and affect its molecular functioning. Here, the chemical reactivity of CEs towards specific amino acid residues of proteins and the structural and functional changes induced by the estrogenization of insulin were studied using cyclic voltammetry, liquid chromatography-mass spectrometry, circular dichroism spectroscopy, molecular modeling, and bioassays. Our results indicate that CEs, namely, 2- and 4-hydroxyl estrogens, were thermodynamically and kinetically more reactive than the catechol moiety. Upon co-incubation, intact insulin formed a substantial number of adducts with one or multiple CEs via covalent conjugation at its Cys 7 in the A or B chain, as well as at His10 or Lys29 in the B chain. Such conjugation was coupled with the cleavage of inter-chain disulfide linkages. Estrogenization on these sites may block the receptor-binding pockets of insulin. Insulin signaling and glucose uptake levels were lower in MCF-7 cells treated with modified insulin than in cells treated with native insulin. Taken together, our findings demonstrate that insulin molecules are susceptible to active estrogenization, and that such modification may alter the action of insulin. PMID:27353345

  11. N-Acetylcysteine blocks formation of cancer-initiating estrogen-DNA adducts in cells

    PubMed Central

    Zahid, Muhammad; Saeed, Muhammad; Ali, Mohammed F.; Rogan, Eleanor G.; Cavalieri, Ercole L.

    2010-01-01

    Catechol estrogens, especially 4-hydroxylated metabolites of 17β-estradiol (E2), are responsible for estrogen-induced carcinogenesis. 4-Hydroxyestradiol (4-OHE2), a major metabolite of E2 formed preferentially by cytochrome P-450 1B1, is oxidized to E2-3,4-quinone, which can react with DNA to yield the depurinating adducts 4-OHE2-1-N3Ade and 4-OHE2-1-N7Gua. The apurinic sites generated by the loss of these depurinating adducts induce mutations that could lead to cancer initiation. In the present study, we have evaluated the effects of N-acetycysteine (NAcCys) on the metabolism of two cell lines, MCF-10F (a normal human breast epithelial cell line) and E6 (a normal mouse mammary epithelial cell line), treated with 4-OHE2 or its reactive metabolite, E2-3,4-quinone. Extensive HPLC with electrochemical detection and UPLC-MS/MS analyses of the cell media demonstrated that the presence of NAcCys very efficiently shifted the estrogen metabolism towards protective methoxylation and conjugation pathways in multiple ways, while formation of depurinating DNA adducts was inhibited. Protection by NAcCys appears to be similar in both cell lines irrespective of their origin (human or mouse) or the presence of estrogen receptor-alpha. This finding suggests that NAcCys, a common dietary supplement, could be used as a potential chemopreventive agent to block the initial step in the genotoxicity caused by catechol estrogen quinones. PMID:20472053

  12. Schistosome and liver fluke derived catechol-estrogens and helminth associated cancers

    PubMed Central

    Correia da Costa, José M.; Vale, Nuno; Gouveia, Maria J.; Botelho, Mónica C.; Sripa, Banchob; Santos, Lúcio L.; Santos, Júlio H.; Rinaldi, Gabriel; Brindley, Paul J.

    2014-01-01

    Infection with helminth parasites remains a persistent public health problem in developing countries. Three of these pathogens, the liver flukes Clonorchis sinensis, Opisthorchis viverrini and the blood fluke Schistosoma haematobium, are of particular concern due to their classification as Group 1 carcinogens: infection with these worms is carcinogenic. Using liquid chromatography-mass spectrometry (LC-MS/MS) approaches, we identified steroid hormone like (e.g., oxysterol-like, catechol estrogen quinone-like, etc.) metabolites and related DNA-adducts, apparently of parasite origin, in developmental stages including eggs of S. haematobium, in urine of people with urogenital schistosomiasis, and in the adult stage of O. viverrini. Since these kinds of sterol derivatives are metabolized to active quinones that can modify DNA, which in other contexts can lead to breast and other cancers, helminth parasite associated sterols might induce tumor-like phenotypes in the target cells susceptible to helminth parasite associated cancers, i.e., urothelial cells of the bladder in the case of urogenital schistosomiasis and the bile duct epithelia or cholangiocytes, in the case of O. viverrini and C. sinensis. Indeed we postulate that helminth induced cancers originate from parasite estrogen-host epithelial/urothelial cell chromosomal DNA adducts, and here we review recent findings that support this conjecture. PMID:25566326

  13. Mechanism of metabolic activation and DNA adduct formation by the human carcinogen diethylstilbestrol: The defining link to natural estrogens

    PubMed Central

    Saeed, Muhammad; Rogan, Eleanor

    2009-01-01

    Diethylstilbestrol (DES) is a human carcinogen, based on sufficient epidemiological evidence. DES is mainly metabolized to its catechol, 3′-hydroxyDES (3′-OH-DES), which can further oxidize to DES-3′,4′-quinone (DES-3′,4′-Q). Similarly to estradiol-3,4-quinone, the reaction of DES-3′,4′-Q with DNA would form the depurinating 3′-OH-DES-6′-N3Ade and 3′-OH-DES-6′-N7Gua adducts. To prove this hypothesis, synthesis of DES-3′,4′-Q by oxidation of 3′-OH-DES with Ag2O was tried; this failed due to instantaneous formation of a spiro-quinone. Oxidation of 3′-OH-DES by lactoperoxidase or tyrosinase in the presence of DNA led to the formation of 3′-OH-DES-6′-N3Ade and 3′-OH-DES-6′-N7Gua adducts. These adducts were tentatively identified by LC-MS/MS as 3′-OH-DES-6′-N3Ade, m/z = 418 [M+H]+, and 3′-OH-DES-6′-N7Gua, m/z = 434 [M+H]+. Demonstration of their structures derived from their oxidation by MnO2 to the DES quinone adducts and subsequent tautomerization to the dienestrol (DIES) catechol adducts, which are identical to the standard 3′-OH-DIES-6′-N3Ade, m/z = 416 [M+H]+, and 3′-OH-DIES-6′-N7Gua, m/z = 432 [M+H]+, adducts. The reaction of DIES-3′,4′-Q or lactoperoxidase-activated 3′-OH-DIES with DNA did not produce any depurinating adducts, due to the dienic chain being perpendicular to the phenyl planes, which impedes the intercalation of DIES into the DNA. Enzymic oxidation of 3′-OH-DES suggests that the catechol of DES intercalates into DNA and is then oxidized to its quinone to yield N3Ade and N7Gua adducts. These results suggest that the common denominator of tumor initiation by the synthetic estrogen DES and the natural estrogen estradiol is formation of their catechol quinones, which react with DNA to afford the depurinating N3Ade and N7Gua adducts. PMID:19089919

  14. Mass spectrometric analysis of catechol-histidine adducts from insect cuticle.

    PubMed

    Kerwin, J L; Turecek, F; Xu, R; Kramer, K J; Hopkins, T L; Gatlin, C L; Yates, J R

    1999-03-15

    Adducts of catechols and histidine, which are produced by reactions of 1,2-quinones and p-quinone methides with histidyl residues in proteins incorporated into the insect exoskeleton, were characterized using electrospray ionization mass spectrometry (ESMS), tandem electrospray mass spectrometry (ESMS-MS, collision-induced dissociation), and ion trap mass spectrometry (ITMS). Compounds examined included adducts obtained from acid hydrolysates of Manduca sexta (tobacco hornworm) pupal cuticle exuviae and products obtained from model reactions under defined conditions. The ESMS and ITMS spectra of 6-(N-3')-histidyldopamine [6-(N-3')-His-DA, pi isomer] isolated from M. sexta cuticle were dominated by a [M + H]+ ion at m/z 308, rather than the expected m/z 307. High-resolution fast atom bombardment MS yielded an empirical formula of C14H18N3O5, which was consistent with this compound being 6-(N-1')-histidyl-2-(3, 4-dihydroxyphenyl)ethanol [6-(N-1')-His-DOPET] instead of a DA adduct. Similar results were obtained when histidyl-catechol compounds linked at C-7 of the catechol were examined; the (N-1') isomer was confirmed as a DA adduct, and the (N-3') isomer identified as an (N-1')-DOPET derivative. Direct MS analysis of unfractionated cuticle hydrolysate revealed intense parent and product ions characteristic of 6- and 7-linked adducts of histidine and DOPET. Mass spectrometric analysis of model adducts synthesized by electrochemical oxidative coupling of N-acetyldopamine (NADA) quinone and N-acetylhistidine (NAcH) identified the point of attachment in the two isomers. A prominent product ion corresponding to loss of CO2 from [M + H]+ of 2-NAcH-NADA confirmed this as being the (N-3') isomer. Loss of (H2O + CO) from 6-NAcH-NADA suggested that this adduct was the (N-1') isomer. The results support the hypothesis that insect cuticle sclerotization involves the formation of C-N cross-links between histidine residues in cuticular proteins, and both ring and side

  15. A Novel Mechanism for Adenylyl Cyclase Inhibition from the Crystal Structure of its Complex with Catechol Estrogen

    SciTech Connect

    Steegborn,C.; Litvin, T.; Hess, K.; Capper, A.; Taussig, R.; Buck, J.; Levin, L.; Wu, H.

    2005-01-01

    Catechol estrogens are steroid metabolites that elicit physiological responses through binding to a variety of cellular targets. We show here that catechol estrogens directly inhibit soluble adenylyl cyclases and the abundant trans-membrane adenylyl cyclases. Catechol estrogen inhibition is non-competitive with respect to the substrate ATP, and we solved the crystal structure of a catechol estrogen bound to a soluble adenylyl cyclase from Spirulina platensis in complex with a substrate analog. The catechol estrogen is bound to a newly identified, conserved hydrophobic patch near the active center but distinct from the ATP-binding cleft. Inhibitor binding leads to a chelating interaction between the catechol estrogen hydroxyl groups and the catalytic magnesium ion, distorting the active site and trapping the enzyme substrate complex in a non-productive conformation. This novel inhibition mechanism likely applies to other adenylyl cyclase inhibitors, and the identified ligand-binding site has important implications for the development of specific adenylyl cyclase inhibitors.

  16. Effects of the co-carcinogen catechol on benzo(a)pyrene metabolism and DNA adduct formation in mouse skin

    SciTech Connect

    Melikian, A.A.; Leszczynska, J.M.; Hecht, S.S.; Hoffmann, D.

    1986-01-01

    We have studied the effects of the co-carcinogen catechol (1,2-dihydroxybenzene) on the metabolic activation of (/sup 3/H) benzo(a)pyrene (BaP) in mouse skin, in vivo and on the binding of BaP metabolites to DNA and protein at intervals from 0.5-24 h. Upon topical application of 0.015 mg (/sup 3/H)BaP and 0.25 or 0.5 mg catechol per mouse, catechol had little effect on the total amount of (/sup 3/H)BaP metabolized in mouse skin, but it affected the relative proportions of (/sup 3/H)BaP metabolites. Catechol (0.5 mg/mouse) decreased the proportion of water-soluble (/sup 3/H)BaP metabolites, ethyl acetate-soluble polar metabolites and quinones, but doubled the levels of unconjugated 3-hydroxy-BaP at all measured intervals after treatment. Catechol also caused a small increase in the levels of trans-7,8-dihydroxy-7,8-dihydroBaP and trans-9,10-dihydroxy-9,10-dihydroBaP 0.5 h after treatment. Two hours after treatment, the levels of these metabolites subsided to those of the controls. Catechol did not affect the levels of glutathione conjugates of BaP. However, it caused a decrease in glucuronide and sulphate conjugate formation from BaP. Catechol caused an approximately 2-fold increase in the formation of anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydroBaP (BPDE) DNA adducts and elevated the ratio of anti-syn-BPDE-DNA adducts 1.6 to 2.9-fold. Catechol treatment increased the radioactivity associated with epidermal proteins after (/sup 3/H)BaP application. Because catechol increased levels of 3-hydroxyBaP, we considered the possibility that 3-hydroxyBaP might enhance the tumor initiating activities of BaP or BPDE in mouse skin; a bioassay demonstrated that this was not the case. The results of this study indicate that one important effect of catechol related to its co-carcinogenicity is its ability to enhance formation of anti-BPDE-DNA adducts in mouse skin.

  17. Synthesis of the catechols of natural and synthetic estrogens by using 2-iodoxybenzoic acid (IBX) as the oxidizing agent.

    PubMed

    Saeed, Muhammad; Zahid, Muhammad; Rogan, Eleanor; Cavalieri, Ercole

    2005-03-01

    A method for the synthesis of 2-hydroxyestrone/estradiol, 4-hydroxyestrone/estradiol, 3'-hydroxydiethylstilbestrol, 3'-hydroxyhexestrol, and 3'-hydroxydienestrol is reported, in which 2-iodoxybenzoic acid (IBX) and the corresponding phenolic estrogen are reacted. Treatment of the natural estrogens, estrone/estradiol, with stoichiometric amounts of IBX in dimethylformamide initially yielded a mixture of estrone/estradiol-2,3- and -3,4-quinones, which were reduced in situ to the corresponding catechols by treatment with a 1 M aqueous solution of ascorbic acid. Chromatographic separation of the reaction products afforded 2- and 4-hydroxyestrone/estradiol in good overall yields (79%). In the case of the synthetic estrogens containing two identical phenolic rings, protection of one ring is a prerequisite for the synthesis of the monocatechol. Thus, diethylstilbestrol and dienestrol were protected at one phenol ring as their methyl ethers. The resulting monophenols were treated with stoichiometric amounts of IBX for 1 h, followed by treatment with 1 M aqueous ascorbic acid to obtain the corresponding catechols in more than 70% yield. Furthermore, the catechol of diethylstilbestrol, protected at one ring, was reduced by catalytic hydrogenation at the C3-C4 double bond to obtain 3'-hydroxyhexestrol in 90% yield. Removal of the protected methoxy groups of the synthetic estrogen catechols was carried out by treatment with a 1 M solution of boron tribromide in dichloromethane. This method is highly efficient for the preparative scale synthesis of catechols of both natural and synthetic estrogens.

  18. Inhibition of human catechol-O-methyltransferase (COMT)-mediated O-methylation of catechol estrogens by major polyphenolic components present in coffee.

    PubMed

    Zhu, Bao Ting; Wang, Pan; Nagai, Mime; Wen, Yujing; Bai, Hyoung-Woo

    2009-01-01

    In the present study, we investigated the inhibitory effect of three catechol-containing coffee polyphenols, chlorogenic acid, caffeic acid and caffeic acid phenethyl ester (CAPE), on the O-methylation of 2- and 4-hydroxyestradiol (2-OH-E(2) and 4-OH-E(2), respectively) catalyzed by the cytosolic catechol-O-methyltransferase (COMT) isolated from human liver and placenta. When human liver COMT was used as the enzyme, chlorogenic acid and caffeic acid each inhibited the O-methylation of 2-OH-E(2) in a concentration-dependent manner, with IC(50) values of 1.3-1.4 and 6.3-12.5 microM, respectively, and they also inhibited the O-methylation of 4-OH-E(2), with IC(50) values of 0.7-0.8 and 1.3-3.1 microM, respectively. Similar inhibition pattern was seen with human placental COMT preparation. CAPE had a comparable effect as caffeic acid for inhibiting the O-methylation of 2-OH-E(2), but it exerted a weaker inhibition of the O-methylation of 4-OH-E(2). Enzyme kinetic analyses showed that chlorogenic acid and caffeic acid inhibited the human liver and placental COMT-mediated O-methylation of catechol estrogens with a mixed mechanism of inhibition (competitive plus noncompetitive). Computational molecular modeling analysis showed that chlorogenic acid and caffeic acid can bind to human soluble COMT at the active site in a similar manner as the catechol estrogen substrates. Moreover, the binding energy values of these two coffee polyphenols are lower than that of catechol estrogens, which means that coffee polyphenols have higher binding affinity for the enzyme than the natural substrates. This computational finding agreed perfectly with our biochemical data.

  19. Breast cancer risk associated with genotype polymorphism of the catechol estrogen-metabolizing genes: a multigenic study on cancer susceptibility.

    PubMed

    Cheng, Ting-Chih; Chen, Shou-Tung; Huang, Chiun-Sheng; Fu, Yi-Ping; Yu, Jyh-Cherng; Cheng, Chun-Wen; Wu, Pei-Ei; Shen, Chen-Yang

    2005-01-20

    Estrogen has been suggested to trigger breast cancer development via an initiating mechanism involving its metabolite, catechol estrogen (CE). To examine this hypothesis, we carried out a multigenic case-control study of 469 incident breast cancer patients and 740 healthy controls to define the role of important genes involved in the different metabolic steps that protect against the potentially harmful effects of CE metabolism. We studied the 3 genes involved in CE detoxification by conjugation reactions involving methylation (catechol-O-methyltransferase, COMT), sulfation (sulfotransferase 1A1, SULT1A1), or glucuronidation (UDP-glucuronosyltransferase 1A1, UGT1A1), one (manganese superoxide dismutase, MnSOD) involved in protection against reactive oxidative species-mediated oxidation during the conversion of CE-semiquinone (CE-SQ) to CE-quinone (CE-Q), and 2 of the glutathione S-transferase superfamily, GSTM1 and GSTT1, involved in CE-Q metabolism. Support for this hypothesis came from the observations that (i) there was a trend toward an increased risk of breast cancer in women harboring a greater number of putative high-risk genotypes of these genes (p < 0.05); (ii) this association was stronger and more significant in those women who were more susceptible to estrogen [no history of pregnancy or older (> or =26 years) at first full-term pregnancy (FFTP)]; and (iii) the risks associated with having one or more high-risk genotypes were not the same in women having experienced different menarche-to-FFTP intervals, being more significant in women having been exposed to estrogen for a longer period (> or =12 years) before FFTP. Furthermore, because CE-Q can attack DNA, leading to the formation of double-strand breaks (DSB), we examined whether the relationship between cancer risk and the genotypic polymorphism of CE-metabolizing genes was modified by the genotypes of DSB repair genes, and found that a joint effect of CE-metabolizing genes and one of the two DSB

  20. Unbalanced Estrogen Metabolism in Ovarian Cancer

    PubMed Central

    Zahid, Muhammad; Beseler, Cheryl L.; Hall, James B.; LeVan, Tricia; Cavalieri, Ercole L.; Rogan, Eleanor G.

    2013-01-01

    Greater exposure to estrogens is a risk factor for ovarian cancer. To investigate the role of estrogens in ovarian cancer, a spot urine sample and a saliva sample were obtained from 33 women with ovarian cancer and 34 age-matched controls. Thirty-eight estrogen metabolites, conjugates and DNA adducts were analyzed in the urine samples by using ultraperformance liquid chromatography/tandem mass spectrometry, and the ratio of adducts to metabolites and conjugates was calculated for each sample. The ratio of depurinating estrogen-DNA adducts to estrogen metabolites and conjugates was significantly higher in cases compared to controls (p<0.0001), demonstrating high specificity and sensitivity. DNA was purified from the saliva samples and analyzed for genetic polymorphisms in the genes for two estrogen-metabolizing enzymes. Women with two low-activity alleles of catechol-O-methyltransferase plus one or two high-activity alleles of cytochrome P450 1B1 had higher levels of estrogen-DNA adducts and were more likely to have ovarian cancer. These findings indicate that estrogen metabolism is unbalanced in ovarian cancer and suggest that formation of estrogen-DNA adducts plays a critical role in the initiation of ovarian cancer. PMID:24170413

  1. Imbalanced Estrogen Metabolism in the Brain: Possible Relevance to the Etiology of Parkinson’s Disease

    PubMed Central

    Gaikwad, Nilesh W.; Murman, Daniel; Beseler, Cheryl L.; Zahid, Muhammad; Rogan, Eleanor G.; Cavalieri, Ercole L.

    2011-01-01

    Damage to DNA by dopamine quinone and/or catechol estrogen quinones may play a significant role in the initiation of Parkinson’s disease (PD). Depurinating estrogen-DNA adducts are shed from cells and excreted in urine. The aim of this study was to discover whether higher levels of estrogen-DNA adducts are associated with PD. Forty estrogen metabolites, conjugates and DNA adducts were analyzed in urine samples from 20 PD cases and 40 matched controls by using ultraperformance liquid chromatography/tandem mass spectrometry. The levels of adducts in cases vs controls (p<0.005) suggest that unbalanced estrogen metabolism could play a causal role in the initiation of PD. PMID:21692648

  2. Modulation of catechol estrogen synthesis by rat liver microsomes: effects of treatment with growth hormone or testosterone

    SciTech Connect

    Quail, J.A.; Jellinck, P.H.

    1987-09-01

    The ability of GH from various mammalian species, administered to normal mature male rats by constant infusion, to decrease the hepatic 2-hydroxylation of estradiol (E2) to female levels, as measured by the release of /sup 3/H/sub 2/O from (2-3H)E2, was determined. Rat and human GH (hGH) showed the highest activity while ovine GH was inactive. PRL (0.6 IU/h X kg) administered together with hGH (0.02 IU/h X kg) did not antagonize the feminizing action of GH. Infusion of hGH into male rats decreased the affinity of estradiol 2-hydroxylase for its steroid substrate and altered the linear Lineweaver-Burk plot towards a nonlinear hyperbolic plot characteristic of the female. The apparent Michaelis-Menten constant (Km) for the reaction was 1.69 microM for males and 2.75 microM for testosterone-treated ovariectomized females. An equal mixture of liver microsomes from male and female rats gave kinetic values similar to those observed with males alone. Neonatal imprinting with androgen did not alter the magnitude of the response of female rats to treatment with testosterone and/or GH at maturity and the androgen effect could only be shown in ovariectomized animals. The results with rats of different endocrine status were corroborated by the kinetic data and by the pattern of metabolites obtained with (4-/sup 14/C)E2 when examined by TLC and autoradiography. The hormonal control of estradiol 2-hydroxylase, the key enzyme in catechol estrogen formation, and the contribution of sex-specific multiple forms of the enzyme to this reaction are discussed.

  3. Genetic polymorphisms of estrogen receptor alpha and catechol-O-methyltransferase genes in Turkish patients with familial prostate carcinoma

    PubMed Central

    Pazarbasi, Ayfer; Yilmaz, M. Bertan; Alptekin, Davut; Luleyap, Umit; Tansug, Zuhtu; Ozpak, Lutfiye; Izmirli, Muzeyyen; Onatoglu-Arikan, Dilge; Kocaturk-Sel, Sabriye; Erkoc, Mehmet Ali; Turgut, Ozgur; Bereketoglu, Ceyhun; Tunc, Erdal; Akbal, Eylul

    2013-01-01

    OBJECTIVES: Estrogen is one of the most crucial hormones participating in the proliferation and carcinogenesis of the prostate glands. Genetic polymorphisms in the estrogen metabolism pathway might be involved in the risk of prostate carcinoma development. We evaluated the association between genetic polymorphisms in estrogen receptor alpha (ESR1) and catechol-O-methyltransferase (COMT) genes and the risk of developing familial prostate carcinoma. MATERIALS AND METHODS: In this study, 34 cases with prostate carcinoma whose first-degree relatives had prostate carcinoma and 30 healthy age-matched male controls were enrolled. The genotypes of ESR1 and COMT genes were analyzed employing polymerase chain reaction-restriction fragment length polymorphism method. 34 cases with prostate carcinoma, whose first degree relatives had prostate carcinoma and 14 age-matched male controls were enrolled to analyze the genotype of these two genes. RESULTS: Among control patients, the ESR1 PvuII genotypes of C/C, C/T and T/T were observed in 37%, 26% and 37%, respectively, whereas the C/C, C/T and T/T genotypes were observed in 18%, 41% and 41% of case patients, respectively. Among controls, the ESR1 PvuII allele frequencies of C and T were equally observed, whereas the C and T allele frequencies were observed in 38% and 62% of patients, respectively. Among ESR1 PvuII genotypes there were not any significant difference in terms of genotype (P = 0.199) and allele (P = 0.181) frequencies. Among controls, the ESR1 XbaI genotypes of G/G, G/A and A/A were observed in 33%, 37% and 33%, respectively, whereas the G/G, G/A and A/A genotypes were observed in 12%, 47% and 41% of patients, respectively. Among controls, the ESR1 XbaI allele frequencies of A and G were observed equally, respectively, whereas the A and G frequencies were observed in 65% and 35% of patients, respectively. Among ESR1 Χ baI, there was not any significant difference in terms of genotype (P = 0.111) and allele (P = 0

  4. Benzene and dopamine catechol quinones could initiate cancer or neurogenic disease.

    PubMed

    Zahid, Muhammad; Saeed, Muhammad; Rogan, Eleanor G; Cavalieri, Ercole L

    2010-01-15

    Catechol quinones of estrogens react with DNA by 1,4-Michael addition to form depurinating N3Ade and N7Gua adducts. Loss of these adducts from DNA creates apurinic sites that can generate mutations leading to cancer initiation. We compared the reactions of the catechol quinones of the leukemogenic benzene (CAT-Q) and N-acetyldopamine (NADA-Q) with 2'-deoxyguanosine (dG) or DNA. NADA was used to prevent intramolecular cyclization of dopamine quinone. Reaction of CAT-Q or NADA-Q with dG at pH 4 afforded CAT-4-N7dG or NADA-6-N7dG, which lost deoxyribose with a half-life of 3 h to form CAT-4-N7Gua or 4 h to form NADA-6-N7Gua. When CAT-Q or NADA-Q was reacted with DNA, N3Ade adducts were formed and lost from DNA instantaneously, whereas N7Gua adducts were lost over several hours. The maximum yield of adducts in the reaction of CAT-Q or NADA-Q with DNA at pH 4 to 7 was at pH 4. When tyrosinase-activated CAT or NADA was reacted with DNA at pH 5 to 8, adduct levels were much higher (10- to 15-fold), and the highest yield was at pH 5. Reaction of catechol quinones of natural and synthetic estrogens, benzene, naphthalene, and dopamine with DNA to form depurinating adducts is a common feature that may lead to initiation of cancer or neurodegenerative disease.

  5. Catechol estrogen formation by brain tissue: characterization of a direct product isolation assay for estrogen-2- and 4-hydroxylase activity and its application to studies of 2- and 4-hydroxyestradiol formation by rabbit hypothalamus

    SciTech Connect

    Hersey, R.M.; Williams, K.I.; Weisz, J.

    1981-12-01

    A direct product isolation assay for quantifying the formation of 2- and 4-hydroxyestradiol (2-OHE2 and 4-OHE2) from (6,7-3H)estradiol by rabbit hypothalami in vitro was developed, and the assay was used to characterize some properties of estrogen-2- and 4-hydroxylase activity in this tissue. The reaction was carried out under conditions that minimized further metabolism of enzymatically formed catechol estrogens. A simple two-step separation procedure, involving the use of a neutral alumina column, followed by thin layer chromatography, was developed to isolate the enzymatically formed catechol estrogens in a radiochemically homogeneous form. The detergent, Tween-80, was found to activate the enzyme and was used routinely at a concentration of 0.1% in the assay. The formation of 2-OHE2 was linear up to 10 min and with increasing protein concentrations up to 150 micrograms/incubation. Similar values were obtained for 4-OHE2. Maximum velocities (Vmax) for the formation of 2- and 4-OHE2 were 190 and 270 pmol/mg protein . 10 min, respectively. The apparent Km values with respect to estradiol for 2-OHE2 and 4-OHE2 were 125 and 150 microM, respectively. The highest specific activity for the enzyme was present in the 100,000 X g supernatant (S3), while the activity in the microsomal fraction (P3) was less than that in the original homogenate. Enzyme activity depended on the presence of NADPH and oxygen and was inhibited by CO as well as by high concentrations of SKF-525A. Estrogen-2- and 4-hydroxylase activity in rabbit hypothalamus differed from that in rat liver in two respects. In the liver, enzyme activity was localized in the microsomal fraction and was virtually abolished by Tween-80. In contrast, enzyme activity in rabbit hypothalamus was maximal in the soluble fraction (100,000 X g supernatant)and was stimulated by the detergent.

  6. Effect of Tumour Necrosis Factor-Alpha on Estrogen Metabolic Pathways in Breast Cancer Cells

    PubMed Central

    Kamel, Marwa; Shouman, Samia; El-Merzebany, Mahmoud; Kilic, Gokhan; Veenstra, Timothy; Saeed, Muhammad; Wagih, Mohamed; Diaz-Arrastia, Concepcion; Patel, Deepa; Salama, Salama

    2012-01-01

    Tumor necrosis factor-alpha (TNF-α) is a proinflammatory cytokine that has been linked to breast cancer development. Estrogen metabolic pathway is also involved in breast carcinogenesis and DNA adducts formation. In this study we investigated the effect of TNF-α on the estrogen metabolic pathway in MCF-7, a breast cancer cell line. Capillary liquid chromatography/mass spectrometry (LC/MS) and High performance liquid chromatography (HPLC) were used for analysis of estrogen metabolites and estrogen-DNA adducts levels respectively. Reporter gene assay, Real time reverse transcription polymerase chain reaction (real time RT-PCR) and Western blot were used to assess the expression of estrogen metabolizing genes and enzymes. TNF-α significantly increased the total EM and decreased the estrone (E1) / 17-β estradiol (E2) ratio. Moreover, it altered the expression of genes and enzymes involved in E2 activation and deactivation pathways e.g. Cytochrome P-450 1A1 (CYP1A1), Cytochrome P-450 1B1 (CYP1B1), Catechol-O-methyl transferase (COMT) and Nicotinamide adenine dinucleotide phosphate-quinone oxidoreductase 1 (NQO1). In addition, there were increased levels of some catechol estrogens e.g. 4-hydroxy-estrone (4-OHE1) and 2-hydroxyestradiol (2-OHE2) with decreased levels of methylated catechols e.g. 2-methoxy estradiol (2-MeOE2). DNA adducts especially 4-OHE1-[2]-1-N3 Adenine was significantly increased. TNF-α directs the estrogen metabolism into more hormonally active and carcinogenic products in MCF-7. This may implicate a new possible explanation for inflammation associated breast cancer. PMID:22866165

  7. Antineoplastic effect of iodine and iodide in dimethylbenz[a]anthracene-induced mammary tumors: association between lactoperoxidase and estrogen-adduct production.

    PubMed

    Soriano, Ofelia; Delgado, Guadalupe; Anguiano, Brenda; Petrosyan, Pavel; Molina-Servín, Edith D; Gonsebatt, Maria E; Aceves, Carmen

    2011-08-01

    Several groups, including ours, have reported that iodine exhibited antiproliferative and apoptotic effects in various cancer cells only if this element is supplemented as molecular iodine, or as iodide, to cells that are able to oxidize it with the enzyme thyroperoxidase. In this study, we analyzed the effect of various concentrations of iodine and/or iodide in the dimethylbenz[a]anthracene (DMBA) mammary cancer model in rats. The results show that 0.1% iodine or iodide increases the expression of peroxisome proliferator-activated receptor type γ (PPARγ), triggering caspase-mediated apoptosis pathways in damaged mammary tissue (DMBA-treated mammary gland) as well as in frank mammary tumors, but not in normal mammary gland. DMBA treatment induces the expression of lactoperoxidase, which participates in the antineoplastic effect of iodide and could be involved in the pro-neoplastic effect of estrogens, increasing the formation of DNA adducts. In conclusion, our results show that a supplement of 0.1% molecular iodine/potassium iodide (0.05/0.05%) exert antineoplastic effects, preventing estrogen-induced DNA adducts and inducing apoptosis through PPARγ/caspases in pre-cancer and cancerous cells. Since this iodine concentration does not modify the cytology (histology, apoptosis rate) or physiology (triiodothyronine and thyrotropin) of the thyroid gland, we propose that it be considered as an adjuvant treatment for premenopausal mammary cancer.

  8. Catechol oxidase activity of a series of new dinuclear copper(II) complexes with 3,5-DTBC and TCC as substrates: syntheses, X-ray crystal structures, spectroscopic characterization of the adducts and kinetic studies.

    PubMed

    Banu, Kazi Sabnam; Chattopadhyay, Tanmay; Banerjee, Arpita; Bhattacharya, Santanu; Suresh, Eringathodi; Nethaji, Munirathinam; Zangrando, Ennio; Das, Debasis

    2008-08-18

    A series of dinuclear copper(II) complexes has been synthesized with the aim to investigate their applicability as potential structure and function models for the active site of catechol oxidase enzyme. They have been characterized by routine physicochemical techniques as well as by X-ray single-crystal structure analysis: [Cu 2(H 2L2 (2))(OH)(H 2O)(NO 3)](NO 3) 3.2H 2O ( 1), [Cu(HL1 (4))(H 2O)(NO 3)] 2(NO 3) 2.2H 2O ( 2), [Cu(L1 (1))(H 2O)(NO 3)] 2 ( 3), [Cu 2(L2 (3))(OH)(H 2O) 2](NO 3) 2, ( 4) and [Cu 2(L2 (1))(N 3) 3] ( 5) [L1 = 2-formyl-4-methyl-6R-iminomethyl-phenolato and L2 = 2,6-bis(R-iminomethyl)-4-methyl-phenolato; for L1 (1) and L2 (1), R = N-propylmorpholine; for L2 (2), R = N-ethylpiperazine; for L2 (3), R = N-ethylpyrrolidine, and for L1 (4), R = N-ethylmorpholine]. Dinuclear 1 and 4 possess two "end-off" compartmental ligands with exogenous mu-hydroxido and endogenous mu-phenoxido groups leading to intermetallic distances of 2.9794(15) and 2.9435(9) A, respectively; 2 and 3 are formed by two tridentate compartmental ligands where the copper centers are connected by endogenous phenoxido bridges with Cu-Cu separations of 3.0213(13) and 3.0152(15) A, respectively; 5 is built by an end-off compartmental ligand having exogenous mu-azido and endogenous mu-phenoxido groups with a Cu-Cu distance of 3.133(2) A (mean of two independent molecules). The catecholase activity of all of the complexes has been investigated in acetonitrile and methanol medium by UV-vis spectrophotometric study using 3,5-di- tert-butylcatechol (3,5-DTBC) and tetrachlorocatechol (TCC) as substrates. In acetonitrile medium, the conversion of 3,5-DTBC to 3,5-di- tert-butylbenzoquinone (3,5-DTBQ) catalyzed by 1- 5 is observed to proceed via the formation of two enzyme-substrate adducts, ES1 and ES2, detected spectroscopically for the first time. In methanol medium no such enzyme-substrate adduct has been detected, and the 3,5-DTBC to 3,5-DTBQ conversion is observed to be catalyzed by 1- 5

  9. The Selective Estrogen Receptor Modulator (SERM) Lasofoxifene Forms Reactive Quinones Similar to Estradiol

    PubMed Central

    Michalsen, Bradley T.; Gherezghiher, Teshome B.; Choi, Jaewoo; Esala, R.; Chandrasena, P.; Qin, Zhihui; Thatcher, Gregory R.J.; Bolton, Judy L.

    2012-01-01

    The bioactivation of both endogenous and equine estrogens to electrophilic quinoid metabolites has been postulated as a contributing factor in carcinogenic initiation and/or promotion in hormone sensitive tissues. Bearing structural resemblance to estrogens, extensive studies have shown that many selective estrogen receptor modulators (SERMs) are subject to similar bioactivation pathways. Lasofoxifene (LAS), a third generation SERM which has completed Phase III clinical trials for the prevention and treatment of osteoporosis, is currently approved in the European Union for this indication. Previously, Prakash et al. (Drug Metab. Dispos. 2008, 36, 1218-26) reported that similar to estradiol, two catechol regioisomers of LAS are formed as primary oxidative metabolites, accounting for roughly half of total LAS metabolism. However, the potential for further oxidation of these catechols to electrophilic o-quinones has not been reported. In the present study, LAS was synthesized and its oxidative metabolism investigated in vitro under various conditions. Incubation of LAS with tyrosinase, human liver microsomes, or rat liver microsomes in the presence of GSH as a trapping reagent resulted in formation of two mono-GSH and two di-GSH catechol conjugates which were characterized by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Similar conjugates were also detected in incubations with P450 3A4, P450 2D6, and P450 1B1 supersomes. Interestingly, these conjugates were also detected as major metabolites when compared to competing detoxification pathways such as glucuronidation and methylation. The 7-hydroxylasofoxifene (7-OHLAS) catechol regioisomer was also synthesized and oxidized either chemically or enzymatically to an o-quinone that was shown to form depurinating adducts with DNA. Collectively, these data show that analogous to estrogens, LAS is oxidized to catechols and o-quinones which could potentially contribute to in vivo toxicity for this SERM. PMID

  10. Selective estrogen receptor modulator (SERM) lasofoxifene forms reactive quinones similar to estradiol.

    PubMed

    Michalsen, Bradley T; Gherezghiher, Teshome B; Choi, Jaewoo; Chandrasena, R Esala P; Qin, Zhihui; Thatcher, Gregory R J; Bolton, Judy L

    2012-07-16

    The bioactivation of both endogenous and equine estrogens to electrophilic quinoid metabolites has been postulated as a contributing factor in carcinogenic initiation and/or promotion in hormone sensitive tissues. Bearing structural resemblance to estrogens, extensive studies have shown that many selective estrogen receptor modulators (SERMs) are subject to similar bioactivation pathways. Lasofoxifene (LAS), a third generation SERM which has completed phase III clinical trials for the prevention and treatment of osteoporosis, is currently approved in the European Union for this indication. Previously, Prakash et al. (Drug Metab. Dispos. (2008) 36, 1218-1226) reported that similar to estradiol, two catechol regioisomers of LAS are formed as primary oxidative metabolites, accounting for roughly half of the total LAS metabolism. However, the potential for further oxidation of these catechols to electrophilic o-quinones has not been reported. In the present study, LAS was synthesized and its oxidative metabolism investigated in vitro under various conditions. Incubation of LAS with tyrosinase, human liver microsomes, or rat liver microsomes in the presence of GSH as a trapping reagent resulted in the formation of two mono-GSH and two di-GSH catechol conjugates which were characterized by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Similar conjugates were also detected in incubations with P450 3A4, P450 2D6, and P450 1B1 supersomes. Interestingly, these conjugates were also detected as major metabolites when compared to competing detoxification pathways such as glucuronidation and methylation. The 7-hydroxylasofoxifene (7-OHLAS) catechol regioisomer was also synthesized and oxidized either chemically or enzymatically to an o-quinone that was shown to form depurinating adducts with DNA. Collectively, these data show that analogous to estrogens, LAS is oxidized to catechols and o-quinones which could potentially contribute to in vivo toxicity for this SERM

  11. Identifying the Tautomeric Form of a Deoxyguanosine-Estrogen Quinone Intermediate

    PubMed Central

    Stack, Douglas E.

    2015-01-01

    Mechanistic insights into the reaction of an estrogen o-quinone with deoxyguanosine has been further investigated using high level density functional calculations in addition to the use of 4-hyroxycatecholestrone (4-OHE1) regioselectivity labeled with deuterium at the C1-position. Calculations using the M06-2X functional with large basis sets indicate the tautomeric form of an estrogen-DNA adduct present when glycosidic bonds cleavage occurs is comprised of an aromatic A ring structure. This tautomeric form was further verified by use of deuterium labelling of the catechol precursor use to form the estrogen o-quinone. Regioselective deuterium labelling at the C1-position of the estrogen A ring allows discrimination between two tautomeric forms of a reaction intermediate either of which could be present during glycosidic bond cleavage. HPLC-MS analysis indicates a reactive intermediate with a m/z of 552.22 consistent with a tautomeric form containing no deuterium. This intermediate is consistent with a reaction mechanism that involves: (1) proton assisted Michael addition; (2) re-aromatization of the estrogen A ring; and (3) glycosidic bond cleavage to form the known estrogen-DNA adduct, 4-OHE1-1-N7Gua. PMID:26378590

  12. Selective Estrogen Receptor Modulator Delivery of Quinone Warheads to DNA Triggering Apoptosis in Breast Cancer Cells

    PubMed Central

    Peng, Kuan-wei; Wang, Huali; Qin, Zhihui; Wijewickrama, Gihani T.; Lu, Meiling; Wang, Zhican; Bolton, Judy L.; Thatcher, Gregory R. J.

    2009-01-01

    Estrogen exposure is a risk factor for breast cancer and estrogen oxidative metabolites have been implicated in chemical carcinogenesis. Oxidation of the catechol metabolite of estrone (4-OHE) and the β-naphthohydroquinone metabolite of equilenin (4-OHEN) gives o-quinones that produce ROS and damage DNA by adduction and oxidation. To differentiate hormonal and chemical carcinogensis pathways in estrogen receptor positive ER(+) cells, catechol or β-naphthohydroquinone warheads were conjugated to the selective estrogen receptor modulator (SERM) desmethylarzoxifene (DMA). ER binding was retained in the DMA conjugates; both were antiestrogens with submicromolar potency in mammary and endometrial cells. Cytotoxicity, apoptosis, and caspase-3/7 activation were compared in ER(+) and ER(−)MDA-MB-231 cells, and production of ROS was detected using a fluorescent reporter. Comparison was made to DMA, isolated warheads, and a DMA-mustard. Conjugation of warheads to DMA increased cytotoxicity accompanied by induction of apoptosis and activation of caspase-3/7. Activation of caspase-3/7, induction of apoptosis, and cytotoxicity were all increased significantly in ER(+) cells for the DMA conjugates. ROS production was localized in the nucleus for conjugates in ER(+) cells. Observations are compatible with β-naphthohydroquinone and catechol groups being concentrated in the nucleus by ER binding, where oxidation and ROS production result, concomitant with caspase-dependent apoptosis. The results suggest DNA damage induced by catechol estrogen metabolites can be amplified in ER(+) cells independent of hormonal activity. The novel conjugation of quinone warheads to an ER-targeting SERM gives ER-dependent, enhanced apoptosis in mammary cancer cells of potential application in cancer therapy. PMID:19839584

  13. Unbalanced Estrogen Metabolism in Thyroid Cancer

    PubMed Central

    Zahid, Muhammad; Goldner, Whitney; Beseler, Cheryl L.; Rogan, Eleanor G.; Cavalieri, Ercole L.

    2013-01-01

    Well-differentiated thyroid cancer most frequently occurs in premenopausal women. Greater exposure to estrogens may be a risk factor for thyroid cancer. To investigate the role of estrogens in thyroid cancer, a spot urine sample was obtained from 40 women with thyroid cancer and 40 age-matched controls. Thirty-eight estrogen metabolites, conjugates and DNA adducts were analyzed by using ultraperformance liquid chromatography/tandem mass spectrometry, and the ratio of adducts to metabolites and conjugates was calculated for each sample. The ratio of depurinating estrogen-DNA adducts to estrogen metabolites and conjugates significantly differed between cases and controls (p<0.0001), demonstrating high specificity and sensitivity. These findings indicate that estrogen metabolism is unbalanced in thyroid cancer and suggest that formation of estrogen-DNA adducts might play a role in the initiation of thyroid cancer. PMID:23686454

  14. Genotoxicity and inactivation of catechol metabolites of the mycotoxin zearalenone.

    PubMed

    Fleck, Stefanie C; Hildebrand, Andreas A; Müller, Elisabeth; Pfeiffer, Erika; Metzler, Manfred

    2012-11-01

    Zearalenone (ZEN) is a highly estrogenic mycotoxin produced by Fusarium species. The adverse effects of ZEN and its reductive metabolite α-zearalenol (α-ZEL) are often compared to those of 17β-estradiol (E2) and estrone (E1). These endogenous steroidal estrogens are associated with an increased risk for cancer, which may be mediated by two mechanisms, i.e. (1) hormonal activity and (2) genotoxic effects after cytochrome P450-catalyzed metabolic activation to catechols. Like E1 and E2, ZEN and α-ZEL exhibit marked estrogenicity and also undergo aromatic hydroxylation to catechol metabolites. The subsequent methylation of catechols by catechol-O-methyltransferase (COMT) is generally considered as a detoxifying pathway. Imbalances between the activation and inactivation reactions can lead to the formation of reactive semiquinones and quinones, which can alkylate DNA or produce reactive oxygen species by redox cycling. In the present study, the genotoxicity of the catechol metabolites of ZEN, α-ZEL, E1 and E2 was determined in a cell-free system by measuring 8-oxo-2'-deoxyguanosine using a LC-DAD-MS(2) method. Each of the individual catechols of ZEN, α-ZEL, E1 and E2 induced oxidative DNA damage in calf thymus DNA. The ranking order of the DNA damaging activity was 15-hydroxy-ZEN/α-ZEL ≈ 2/4-hydroxy-E1/E2 > 13-hydroxy-ZEN/α-ZEL. When hepatic microsomes from different species were incubated with ZEN, the rat had the highest activity for catechol formation, followed by human, mouse, pig and steer. The amount of catechol metabolites correlated directly with the amount of oxidative damage in calf thymus DNA. The ranking order for the rate of methylation by human hepatic COMT was 2-hydroxy-E1/E2 > 4-hydroxy-E1/E2 > 13/15-hydroxy-ZEN/α-ZEL. Thus, the catechol metabolites of the mycoestrogen ZEN and its reductive metabolite α-ZEL exhibit a DNA-damaging potential comparable to that of the catechol metabolites of E1 and E2, but are much poorer substrates for

  15. [DNA adducts in human female genital organs].

    PubMed

    Postawski, Krzysztof; Przadka-Rabaniuk, Dorota; Monist, Marta; Baranowski, Włodzimierz

    2007-12-01

    DNA adducts, one of genetic damages markers, precede and finally can lead to oncogenic mutations. They appear in genome as a result of DNA bases damages caused by various and numerous environmental factors eg. ultraviolet light, ionic radiation, toxins and also endogenic substances, for example estrogens. It is believed that the creation of DNA adducts is a necessary but insufficient process for the neoplastic transformation of the cell. The following review presents concise knowledge about the DNA adducts creation and their sequels served in healthy and cancerous tissues of the female genital organs, on the base of the available data. PMID:18411923

  16. Liquid chromatography-tandem mass spectrometric analysis of ten estrogen metabolites at sub-picogram levels in breast cancer women.

    PubMed

    Khedr, Alaa; Alahdal, Abdulrahman M

    2016-09-15

    The measurement of estrogens at sub-picogram levels is essential for research on breast cancer and postmenopausal plasma. Heretofore, these concentration levels have rarely been achieved. However, it is possible through derivatization but still represent problems for monitoring catechol estrogens and 16α-hydroxyestrone (16α-OH-E1). Estrogens possess poor ionization efficiency in MS/MS, which results in insufficient sensitivity for analyzing samples at trace concentrations. The method presented here was used to extract ten estrogen metabolites (EMs) with a derivatization step involving a new adduct. The electrospray ionization (ESI) MS/MS sensitivity for the EMs was enhanced by derivatization with 3-bromomethyl-propyphenazone (BMP). The lower limits of quantification (LLOQ) of the EMs were 12-100 femtogram on-column, equivalent to 0.3-3.6pg/mL plasma, and the limits of detection (LOD) were 0.1-0.8pg/mL plasma. The percentage coefficient of variation (CV%) at the LLOQ was <20 for all investigated EMs. Ionization suppression was minimized by reacting the excess reagent, BMP, with methanol. The method was successfully applied for the determination of ten EMs in the plasma of fifty healthy postmenopausal and fifty ductal breast cancer women aged 47-65 years old. 16α-OH-E1 and three catechol estrogen metabolites, 4-OH-E1, 2-OH-E2 and 4-OH-E2, were successfully measured in the plasma of healthy and breast cancer women. The methyl-propyphenazone-EM derivatives exhibited better sensitivity in ESI-MS (7.5-fold) compared to the commonly used dansylation procedure. PMID:27497156

  17. Chemical properties of catechols and their molecular modes of toxic action in cells, from microorganisms to mammals.

    PubMed

    Schweigert, N; Zehnder, A J; Eggen, R I

    2001-02-01

    Catechols can undergo a variety of chemical reactions. In this review, we particularly focus on complex formations and the redox chemistry of catechols, which play an inportant role in the toxicity of catechols. In the presence of heavy metals, such as iron or copper, stable complexes can be formed. In the presence of oxidizing agents, catechols can be oxidized to semiquinone radicals and in a next step to o-benzoquinones. Heavy metals may catalyse redox reactions in which catechols are involved. Further chemical properties like the acidity constant and the lipophilicity of different catechols are shortly described as well. As a consequence of the chemical properties and the chemical reactions of catechols, many different reactions can occur with biomolecules such as DNA, proteins and membranes, ultimately leading to non-repairable damage. Reactions with nucleic acids such as adduct formation and strand breaks are discussed among others. Interactions with proteins causing protein and enzyme inactivation are described. The membrane-catechol interactions discussed here are lipid peroxidation and uncoupling. The deleterious effect of the interactions between catechols and the different biomolecules is discussed in the context of the observed toxicities, caused by catechols.

  18. Development of an immunoassay to detect benzene adducts in hemoglobin

    SciTech Connect

    Grassman, J.A.

    1993-01-01

    The purpose of this project was to develop an immunoassay to detect the adducts formed in hemoglobin after exposure to benzene, which is known to cause bone marrow degeneration and acute myelogenous leukemia. The use of benzene-adduct detection as a biological monitoring method would permit measurement of low exposures and exposures sustained weeks earlier. The reactivity of hydroquinone, an important benzene metabolite, with blood proteins and amino acids was investigated in order to decide which antigens and analytes were likely to be suitable for immunoassay development. The second section determined the combination of benzene-metabolite and antigen need to produce an immunoassay with the requisite low detection limit and specificity. The immunoassays with the best performance were tested on hemoglobin from benzene-exposed mice. In vitro studies showed that hydroquinone efficiently formed adducts with erythrocyte membranes and hemoglobin but not with albumin. Adduction efficiency was greater in incubations using purified hemoglobin than whole blood. Cysteine accounted for 15 to 27% of the adducts formed by hydroquinone. The site of the other adducts were not identified although there was evidence that the hemoglobin heme was adducted. Adducts were found on only 1 of the 2 globin chains. Tryptic digestion of the globin failed to associate the adducts with a specific peptide. Antigens made from hydroquinone-adducted hemoglobin but not hydroquinone-adducted cysteines coupled to carrier proteins effectively elicited adduct-specific antibodies. Interference due to reactivity to hemoglobin was controlled by using uniform quantities of hemoglobin in all wells. The mid-range of the best assays were approximately 12 pmoles HQ per well. Antibodies directed toward hemoglobin adducted with the benzene metabolites phenol, catechol and 1,2,4-trihydroxybenzene were also made. The performance of the anti-1,2,4-trihydroxybenzene were suitable for quantitative immunoassays.

  19. Heterogeneous Oxidation of Catechol.

    PubMed

    Pillar, Elizabeth A; Zhou, Ruixin; Guzman, Marcelo I

    2015-10-15

    Natural and anthropogenic emissions of aromatic hydrocarbons from biomass burning, agro-industrial settings, and fossil fuel combustion contribute precursors to secondary aerosol formation (SOA). How these compounds are processed under humid tropospheric conditions is the focus of current attention to understand their environmental fate. This work shows how catechol thin films, a model for oxygenated aromatic hydrocarbons present in biomass burning and combustion aerosols, undergo heterogeneous oxidation at the air-solid interface under variable relative humidity (RH = 0-90%). The maximum reactive uptake coefficient of O3(g) by catechol γO3 = (7.49 ± 0.35) × 10(-6) occurs for 90% RH. Upon exposure of ca. 104-μm thick catechol films to O3(g) mixing ratios between 230 ppbv and 25 ppmv, three main reaction pathways are observed. (1) The cleavage of the 1,2 carbon-carbon bond at the air-solid interface resulting in the formation of cis,cis-muconic acid via primary ozonide and hydroperoxide intermediates. Further direct ozonolysis of cis,cis-muconic yields glyoxylic, oxalic, crotonic, and maleic acids. (2) A second pathway is evidenced by the presence of Baeyer-Villiger oxidation products including glutaconic 4-hydroxy-2-butenoic and 5-oxo-2-pentenoic acids during electrospray ionization mass spectrometry (MS) and ion chromatography MS analyses. (3) Finally, indirect oxidation by in situ produced hydroxyl radical (HO(•)) results in the generation of semiquinone radical intermediates toward the synthesis of polyhydoxylated aromatic rings such as tri-, tetra-, and penta-hydroxybenzene. Remarkably, heavier polyhydroxylated biphenyl and terphenyl products present in the extracted oxidized films result from coupling reactions of semiquinones of catechol and its polyhydroxylated rings. The direct ozonolysis of 1,2,3- and 1,2,4-trihydroxybenezene yields 2- and 3-hydroxy-cis,cis-muconic acid, respectively. The production of 2,4- or 3,4-dihdroxyhex-2-enedioic acid is

  20. Estrogen overdose

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/002584.htm Estrogen overdose To use the sharing features on this page, please enable JavaScript. Estrogen is a female hormone. Estrogen overdose occurs when ...

  1. Synthetic models of the active site of catechol oxidase: mechanistic studies.

    PubMed

    Koval, Iryna A; Gamez, Patrick; Belle, Catherine; Selmeczi, Katalin; Reedijk, Jan

    2006-09-01

    The ability of copper proteins to process dioxygen at ambient conditions has inspired numerous research groups to study their structural, spectroscopic and catalytic properties. Catechol oxidase is a type-3 copper enzyme usually encountered in plant tissues and in some insects and crustaceans. It catalyzes the conversion of a large number of catechols into the respective o-benzoquinones, which subsequently auto-polymerize, resulting in the formation of melanin, a dark pigment thought to protect a damaged tissue from pathogens. After the report of the X-ray crystal structure of catechol oxidase a few years earlier, a large number of publications devoted to the biomimetic modeling of its active site appeared in the literature. This critical review (citing 114 references) extensively discusses the synthetic models of this enzyme, with a particular emphasis on the different approaches used in the literature to study the mechanism of the catalytic oxidation of the substrate (catechol) by these compounds. These are the studies on the substrate binding to the model complexes, the structure-activity relationship, the kinetic studies of the catalytic oxidation of the substrate and finally the substrate interaction with (per)oxo-dicopper adducts. The general overview of the recognized types of copper proteins and the detailed description of the crystal structure of catechol oxidase, as well as the proposed mechanisms of the enzymatic cycle are also presented. PMID:16936929

  2. Kinetic study of electrochemically induced michael reactions of o-quinones with Meldrum's acid derivatives. Synthesis of highly oxygenated catechols.

    PubMed

    Nematollahi, D; Shayani-jam, H

    2008-05-01

    Electrochemical oxidation of catechols has been studied in the presence of Meldrum's acid derivatives as nucleophiles in aqueous solution, by means of cyclic voltammetry and controlled-potential coulometry. Catechols in the Michael addition reaction react with Meldrum's acids to form adducts that can undergo electrooxidation. Such products were obtained in good yields as confirmed by controlled potential electrosynthesis. Such products can be generated in aqueous solutions by means of electrosynthesis, using a carbon electrode in an undivided cell. Furthermore, the homogeneous rate constants of the chemical reaction interposed between electron transfers were estimated by comparing the experimental cyclic voltammetric curves with the digitally simulated ones.

  3. Estrogen Injection

    MedlinePlus

    ... forms of estrogen injection are used to treat hot flushes (hot flashes; sudden strong feelings of heat and sweating) ... If you are using estrogen injection to treat hot flushes, your symptoms should improve within 1 to ...

  4. Spectroscopic Studies of the Catechol Dioxygenases.

    ERIC Educational Resources Information Center

    Que, Lawrence Jr.

    1985-01-01

    The catechol dioxygenases are bacterial iron-containing enzymes that catalyze the oxidative cleavage of catechols. These enzymes serve as a component of nature's mechanisms for degrading aromatic compounds in the environment. The structure and mechanistic aspects of these enzymes are described. (JN)

  5. Histone acetyltransferase p300 promotes MKL1-mediated transactivation of catechol-O-methyltransferase gene.

    PubMed

    Liu, Zhipeng; Luo, Xuegang; Liu, Lei; Zhao, Wenwen; Guo, Shu; Guo, Yu; Wang, Nan; He, Hongpeng; Liao, Xinghua; Ma, Wenjian; Zhou, Hao; Zhang, Tongcun

    2013-12-01

    Previous studies have revealed that histone acetyltransferase p300 is recruited to the promoters of certain cardiac and smooth muscle specific genes to enhance the transactivation activity of myocardin, which is a master regulator in cardiovascular differentiation and development. Here, we found that the gene encoding catechol-O-methyltransferase (COMT), an important metabolic enzyme catalyzing the conversion of estrogen, is also a target gene of myocardin-related transcription factors (MRTFs). Megakaryoblastic leukemia 1 (MKL1, also named MRTF-A) and p300 could synergistically augment the expression of COMT gene, increase the metabolic rate of estrogen, and thus reduce the proliferation of MCF-7 breast cancer cells stimulated by estrogen. PMID:24096006

  6. Isolevuglandin Adducts in Disease

    PubMed Central

    Bi, Wenzhao

    2015-01-01

    Abstract Significance: A diverse family of lipid-derived levulinaldehydes, isolevuglandins (isoLGs), is produced by rearrangement of endoperoxide intermediates generated through both cyclooxygenase (COX) and free radical-induced cyclooxygenation of polyunsaturated fatty acids and their phospholipid esters. The formation and reactions of isoLGs with other biomolecules has been linked to alcoholic liver disease, Alzheimer's disease, age-related macular degeneration, atherosclerosis, cardiac arythmias, cancer, end-stage renal disease, glaucoma, inflammation of allergies and infection, mitochondrial dysfunction, multiple sclerosis, and thrombosis. This review chronicles progress in understanding the chemistry of isoLGs, detecting their production in vivo and understanding their biological consequences. Critical Issues: IsoLGs have never been isolated from biological sources, because they form adducts with primary amino groups of other biomolecules within seconds. Chemical synthesis enabled investigation of isoLG chemistry and detection of isoLG adducts present in vivo. Recent Advances: The first peptide mapping and sequencing of an isoLG-modified protein present in human retina identified the modification of a specific lysyl residue of the sterol C27-hydroxylase Cyp27A1. This residue is preferentially modified by iso[4]LGE2 in vitro, causing loss of function. Adduction of less than one equivalent of isoLG can induce COX-associated oligomerization of the amyloid peptide Aβ1-42. Adduction of isoLGE2 to phosphatidylethanolamines causes gain of function, converting them into proinflammatory isoLGE2-PE agonists that foster monocyte adhesion to endothelial cells. Future Directions: Among the remaining questions on the biochemistry of isoLGs are the dependence of biological activity on isoLG isomer structure, the structures and mechanism of isoLG-derived protein–protein and DNA–protein cross-link formation, and its biological consequences. Antioxid. Redox Signal. 22

  7. Alcohol, Aldehydes, Adducts and Airways.

    PubMed

    Sapkota, Muna; Wyatt, Todd A

    2015-11-05

    Drinking alcohol and smoking cigarettes results in the formation of reactive aldehydes in the lung, which are capable of forming adducts with several proteins and DNA. Acetaldehyde and malondialdehyde are the major aldehydes generated in high levels in the lung of subjects with alcohol use disorder who smoke cigarettes. In addition to the above aldehydes, several other aldehydes like 4-hydroxynonenal, formaldehyde and acrolein are also detected in the lung due to exposure to toxic gases, vapors and chemicals. These aldehydes react with nucleophilic targets in cells such as DNA, lipids and proteins to form both stable and unstable adducts. This adduction may disturb cellular functions as well as damage proteins, nucleic acids and lipids. Among several adducts formed in the lung, malondialdehyde DNA (MDA-DNA) adduct and hybrid malondialdehyde-acetaldehyde (MAA) protein adducts have been shown to initiate several pathological conditions in the lung. MDA-DNA adducts are pre-mutagenic in mammalian cells and induce frame shift and base-pair substitution mutations, whereas MAA protein adducts have been shown to induce inflammation and inhibit wound healing. This review provides an insight into different reactive aldehyde adducts and their role in the pathogenesis of lung disease.

  8. Alcohol, Aldehydes, Adducts and Airways.

    PubMed

    Sapkota, Muna; Wyatt, Todd A

    2015-01-01

    Drinking alcohol and smoking cigarettes results in the formation of reactive aldehydes in the lung, which are capable of forming adducts with several proteins and DNA. Acetaldehyde and malondialdehyde are the major aldehydes generated in high levels in the lung of subjects with alcohol use disorder who smoke cigarettes. In addition to the above aldehydes, several other aldehydes like 4-hydroxynonenal, formaldehyde and acrolein are also detected in the lung due to exposure to toxic gases, vapors and chemicals. These aldehydes react with nucleophilic targets in cells such as DNA, lipids and proteins to form both stable and unstable adducts. This adduction may disturb cellular functions as well as damage proteins, nucleic acids and lipids. Among several adducts formed in the lung, malondialdehyde DNA (MDA-DNA) adduct and hybrid malondialdehyde-acetaldehyde (MAA) protein adducts have been shown to initiate several pathological conditions in the lung. MDA-DNA adducts are pre-mutagenic in mammalian cells and induce frame shift and base-pair substitution mutations, whereas MAA protein adducts have been shown to induce inflammation and inhibit wound healing. This review provides an insight into different reactive aldehyde adducts and their role in the pathogenesis of lung disease. PMID:26556381

  9. PEM Anchorage on Titanium Using Catechol Grafting

    PubMed Central

    Marie, Hélène; Barrere, Amélie; Schoentstein, Frédérique; Chavanne, Marie-Hélène; Grosgogeat, Brigitte; Mora, Laurence

    2012-01-01

    Background This study deals with the anchorage of polyelectrolyte films onto titanium surfaces via a cathecol-based linker for biomedical applications. Methodology The following study uses a molecule functionalized with a catechol and a carboxylic acid: 3-(3,4-dihydroxyphenyl)propanoic acid. This molecule is anchored to the TiO2 substrate via the catechol while the carboxylic acid reacts with polymers bearing amine groups. By providing a film anchorage of chemisorption type, it makes possible to deposit polyelectrolytes on the surface of titanium. Principal Findings Infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), contact angle and atomic force microscopy (AFM) measurements show that the different steps of grafting have been successfully performed. Conclusions This method based on catechol anchorage of polyelectrolytes open a window towards large possibilities of clinical applications. PMID:23226262

  10. DNA adducts in bronchial biopsies.

    PubMed

    Dunn, B P; Vedal, S; San, R H; Kwan, W F; Nelems, B; Enarson, D A; Stich, H F

    1991-06-19

    To investigate the feasibility of measuring DNA-carcinogen adducts in the lungs of non-surgical patients, endobronchial biopsies were obtained from 78 patients undergoing routine diagnostic bronchoscopy. Lung cancer was present in 37 (47%) of the patients. DNA was isolated from the tissues and analyzed by HPLC- or nuclease-PI-enriched 32P-postlabelling, using procedures selective for aromatic adducts. Chromatograms from all 28 current smokers showed a distinctive diagonal adduct zone which was present in only 24 of 40 ex-smokers and 4 of 10 lifetime non-smokers. Adduct levels and chromatographic patterns were similar in bronchial tissue from different lobes of the lung, in bronchial and alveolar tissue, and in tumor and non-tumor bronchial tissue taken from the same subject. Bronchial DNA adduct levels were strongly associated with cigarette smoking status and dropped rapidly after smoking ceased. Higher levels of DNA adducts seen in the lung-cancer patients were mainly due to cigarette smoking. Frequent alcohol intake was the only dietary factor associated with higher levels of bronchial DNA adducts. We conclude that the level of bronchial DNA adducts is strongly associated with cigarette-smoking history and with alcohol intake, but is not associated with lung cancer independently from its relation to smoking. The results indicate the feasibility of using 32P-postlabelling to detect and quantitate genetic damage in bronchial biopsy specimens.

  11. The role of catechol-O-methyltransferase in catechol-enhanced erythroid differentiation of K562 cells

    SciTech Connect

    Suriguga,; Li, Xiao-Fei; Li, Yang; Yu, Chun-Hong; Li, Yi-Ran; Yi, Zong-Chun

    2013-12-15

    Catechol is widely used in pharmaceutical and chemical industries. Catechol is also one of phenolic metabolites of benzene in vivo. Our previous study showed that catechol improved erythroid differentiation potency of K562 cells, which was associated with decreased DNA methylation in erythroid specific genes. Catechol is a substrate for the catechol-O-methyltransferase (COMT)-mediated methylation. In the present study, the role of COMT in catechol-enhanced erythroid differentiation of K562 cells was investigated. Benzidine staining showed that exposure to catechol enhanced hemin-induced hemoglobin accumulation and induced mRNA expression of erythroid specific genes in K562 cells. Treatment with catechol caused a time- and concentration-dependent increase in guaiacol concentration in the medium of cultured K562 cells. When COMT expression was knocked down by COMT shRNA expression in K562 cells, the production of guaiacol significantly reduced, and the sensitivity of K562 cells to cytotoxicity of catechol significantly increased. Knockdown of COMT expression by COMT shRNA expression also eliminated catechol-enhanced erythroid differentiation of K562 cells. In addition, the pre-treatment with methyl donor S-adenosyl-L-methionine or its demethylated product S-adenosyl-L-homocysteine induced a significant increase in hemin-induced Hb synthesis in K562 cells and the mRNA expression of erythroid specific genes. These findings indicated that O-methylation catalyzed by COMT acted as detoxication of catechol and involved in catechol-enhanced erythroid differentiation of K562 cells, and the production of S-adenosyl-L-homocysteine partly explained catechol-enhanced erythroid differentiation. - Highlights: • Catechol enhanced hemin-induced hemoglobin accumulation. • COMT-catalyzed methylation acted as detoxication of catechol. • COMT involved in catechol-enhanced erythroid differentiation.

  12. Tamoxifen–DNA adduct formation in monkey and human reproductive organs

    PubMed Central

    Hernandez-Ramon, Elena E.

    2014-01-01

    The estrogen analog tamoxifen (TAM), used for adjuvant therapy of breast cancer, induces endometrial and uterine tumors in breast cancer patients. Proliferation stimulus of the uterine endometrium is likely involved in tumor induction, but genotoxicity may also play a role. Formation of TAM–DNA adducts in human tissues has been reported but remains controversial. To address this issue, we examined TAM–DNA adducts in uteri from two species of monkeys, Erythrocebus patas (patas) and Macaca fascicularis (macaque), and in human endometrium and myometrium. Monkeys were given 3–4 months of chronic TAM dosing scaled to be equivalent to the daily human dose. In the uteri, livers and brains from the patas (n = 3), and endometrium from the macaques (n = 4), TAM–DNA adducts were measurable by TAM–DNA chemiluminescence immunoassay. Average TAM–DNA adduct values for the patas uteri (23 adducts/108 nucleotides) were similar to those found in endometrium of the macaques (19 adducts/108 nucleotides). Endometrium of macaques exposed to both TAM and low-dose estradiol (n = 5) averaged 34 adducts/108 nucleotides. To examine TAM–DNA persistence in the patas, females (n = 3) were exposed to TAM for 3 months and to no drug for an additional month, resulting in low or non-detectable TAM–DNA in livers and uteri. Human endometrial and myometrial samples from women receiving (n = 8) and not receiving (n = 8) TAM therapy were also evaluated. Women receiving TAM therapy averaged 10.3 TAM–DNA adducts/108 nucleotides, whereas unexposed women showed no detectable TAM–DNA. The data indicate that genotoxicity, in addition to estrogen agonist effects, may contribute to TAM-induced human endometrial cancer. PMID:24501327

  13. Modulation of Estrogen Chemical Carcinogenesis by Botanical Supplements used for Postmenopausal Women's Health.

    PubMed

    Snelten, Courtney S; Dietz, Birgit; Bolton, Judy L

    2012-06-01

    Breast cancer risk has been associated with long-term estrogen exposure including traditional hormone therapy (HT, formally hormone replacement therapy). To avoid traditional HT and associated risks, women have been turning to botanical supplements such as black cohosh, red clover, licorice, hops, dong gui, and ginger to relieve menopausal symptoms despite a lack of efficacy evidence. The mechanisms of estrogen carcinogenesis involve both hormonal and chemical pathways. Botanical supplements could protect women from estrogen carcinogenesis by modulating key enzymatic steps [aromatase, P4501B1, P4501A1, catechol-O-methyltransferase (COMT), NAD(P)H quinone oxidoreductase 1 (NQO1), and reactive oxygen species (ROS) scavenging] in estradiol metabolism leading to estrogen carcinogenesis as outlined in Figure 1. This review summarizes the influence of popular botanical supplements used for women's health on these key steps in the estrogen chemical carcinogenesis pathway, and suggests that botanical supplements may have added chemopreventive benefits by modulating estrogen metabolism. PMID:24223609

  14. Aluminum complexation by catechol as determined by ultraviolet spectrophotometry

    SciTech Connect

    Sikora, F.J.; McBride, M.B.

    1989-03-01

    Methods of ultraviolet (UV) spectrophotometry were used to determine the stoichiometry and association constant for the Al-catechol complex from pH 3.8 to 4.6. Job's method of continuous variation indicated the Al-catechol complex had a 1:1 stoichiometry in the pH range studied. Aluminum titrations of catechol and pH titrations of catechol plus Al resulted in a shift in the UV spectra due to the formation of an Al-catechol complex absorbing UV radiation uniquely different than that of free catechol. General equations were developed for the determination of association constants assuming an organic and Al-organic complex absorb UV radiation. Aluminum titrations with constant catechol concentration yielded a log k/sub 0.1//sup c/ of 16.22 for a 1:1 Al-catechol complex. Calculated absorbance as a function of pH agree dwell with experimental pH titrations of solutions containing catechol plus Al. The fact that Al can be complexed by catechol at low pH indicates the o-hydroxy group provides a potential source for Al complexation in soil and surface waters.

  15. The role of catechol-O-methyltransferase in catechol-enhanced erythroid differentiation of K562 cells.

    PubMed

    Suriguga; Li, Xiao-Fei; Li, Yang; Yu, Chun-Hong; Li, Yi-Ran; Yi, Zong-Chun

    2013-12-15

    Catechol is widely used in pharmaceutical and chemical industries. Catechol is also one of phenolic metabolites of benzene in vivo. Our previous study showed that catechol improved erythroid differentiation potency of K562 cells, which was associated with decreased DNA methylation in erythroid specific genes. Catechol is a substrate for the catechol-O-methyltransferase (COMT)-mediated methylation. In the present study, the role of COMT in catechol-enhanced erythroid differentiation of K562 cells was investigated. Benzidine staining showed that exposure to catechol enhanced hemin-induced hemoglobin accumulation and induced mRNA expression of erythroid specific genes in K562 cells. Treatment with catechol caused a time- and concentration-dependent increase in guaiacol concentration in the medium of cultured K562 cells. When COMT expression was knocked down by COMT shRNA expression in K562 cells, the production of guaiacol significantly reduced, and the sensitivity of K562 cells to cytotoxicity of catechol significantly increased. Knockdown of COMT expression by COMT shRNA expression also eliminated catechol-enhanced erythroid differentiation of K562 cells. In addition, the pre-treatment with methyl donor S-adenosyl-L-methionine or its demethylated product S-adenosyl-L-homocysteine induced a significant increase in hemin-induced Hb synthesis in K562 cells and the mRNA expression of erythroid specific genes. These findings indicated that O-methylation catalyzed by COMT acted as detoxication of catechol and involved in catechol-enhanced erythroid differentiation of K562 cells, and the production of S-adenosyl-L-homocysteine partly explained catechol-enhanced erythroid differentiation.

  16. Estrogen Carcinogenesis

    PubMed Central

    Zhang, Qiang; Aft, Rebecca L.; Gross, Michael L.

    2009-01-01

    Prolonged exposure to estrogens correlates with increased risk for breast cancer. One explanation is that estrogen metabolites cause mutations by reacting with DNA, leading to depurination. We describe an extraction procedure and a liquid chromatographic tandem mass spectrometric (LC/MS/MS) assay to detect estrone-metabolite-modified adenine (Ade) in 100-200 mg samples of human breast tissue. To insure reliable analyses, we used a synthetic estrone-metabolite-modified, U-15N labeled Ade as an internal standard (IS). Appropriate high pressure liquid chromatography gives sharp (∼ 5 s at half height) with identical retention times for the analyte and the IS. In breast tissue from women with and without cancer, we found a co-eluting material with similar MS/MS fragmentation as the IS, providing high specificity in the identification of the modified Ade; the recovery was approximately 50%. For women with and without breast cancer, the levels of the modified Ade are in the range of 20-70 fmol/g of breast tissue from five women and not detectable in tissue from another women. The sample size and detection limits are not yet sufficient to permit distinctions between cancer and noncancer patients. PMID:18672910

  17. Synthesis and Evaluation of Heterocyclic Catechol Mimics as Inhibitors of Catechol-O-methyltransferase (COMT)

    PubMed Central

    2015-01-01

    3-Hydroxy-4-pyridinones and 5-hydroxy-4-pyrimidinones were identified as inhibitors of catechol-O-methyltransferase (COMT) in a high-throughput screen. These heterocyclic catechol mimics exhibit potent inhibition of the enzyme and an improved toxicity profile versus the marketed nitrocatechol inhibitors tolcapone and entacapone. Optimization of the series was aided by X-ray cocrystal structures of the novel inhibitors in complex with COMT and cofactors SAM and Mg2+. The crystal structures suggest a mechanism of inhibition for these heterocyclic inhibitors distinct from previously disclosed COMT inhibitors. PMID:25815153

  18. Estrogens and aging skin

    PubMed Central

    Thornton, M. Julie

    2013-01-01

    Estrogen deficiency following menopause results in atrophic skin changes and acceleration of skin aging. Estrogens significantly modulate skin physiology, targeting keratinocytes, fibroblasts, melanocytes, hair follicles and sebaceous glands, and improve angiogenesis, wound healing and immune responses. Estrogen insufficiency decreases defense against oxidative stress; skin becomes thinner with less collagen, decreased elasticity, increased wrinkling, increased dryness and reduced vascularity. Its protective function becomes compromised and aging is associated with impaired wound healing, hair loss, pigmentary changes and skin cancer.   Skin aging can be significantly delayed by the administration of estrogen. This paper reviews estrogen effects on human skin and the mechanisms by which estrogens can alleviate the changes due to aging. The relevance of estrogen replacement, selective estrogen receptor modulators (SERMs) and phytoestrogens as therapies for diminishing skin aging is highlighted. Understanding estrogen signaling in skin will provide a basis for interventions in aging pathologies. PMID:24194966

  19. DNA integrity of onion root cells under catechol influence.

    PubMed

    Petriccione, Milena; Forte, Valentina; Valente, Diego; Ciniglia, Claudia

    2013-07-01

    Catechol is a highly toxic organic pollutant, usually abundant in the waste effluents of industrial processes and agricultural activities. The environmental sources of catechol include pesticides, wood preservatives, tanning lotion, cosmetic creams, dyes, and synthetic intermediates. Genotoxicity of catechol at a concentration range 5 × 10(-1)-5 mM was evaluated by applying random amplified polymorphic DNA (RAPD) and time-lapse DNA laddering tests using onion (Allium cepa) root cells as the assay system. RAPD analysis revealed polymorphisms in the nucleotidic sequence of DNA that reflected the genotoxic potential of catechol to provoke point mutations, or deletions, or chromosomal rearrangements. Time-lapse DNA laddering test provided evidence that catechol provoked DNA necrosis and apoptosis. Acridine orange/ethidium bromide staining could distinguish apoptotic from necrotic cells in root cells of A. cepa.

  20. Photocatalytic reaction of catechol on rutile titanium oxide

    NASA Astrophysics Data System (ADS)

    Jacobson, Peter; Wang, Chundao; Diebold, Ulrike

    2008-03-01

    In an attempt to understand the fundamental aspects of photocatalysis we have studied the substituted benzene catechol on TiO2(110). Previous studies have given detailed information about the catechol bonding configuration letting our group focus on molecular level interactions with scanning tunneling microscopy and X ray photoelectron spectroscopy. Under UV exposure (248 nm) in an oxygen background, catechol is observed to degrade via oxidation. This oxidation process results in removal of roughly 10% of the initial monolayer. The removal of carbon from the TiO2 surface is shown to depend upon the background gas. Formation of a residual carbon layer is achieved by annealing the catechol monolayer to 600C. This carbon layer is more difficult to remove by photocatalytic oxidation than a pristine catechol monolayer. Work supported by Intel Corporation

  1. Estrogen and Osteoporosis.

    ERIC Educational Resources Information Center

    Lindsay, Robert

    1987-01-01

    This article reviews the use of estrogen in the prevention and treatment of osteoporosis. Dosage levels, interactions with other factors, side effects, and the mechanism of estrogen action are discussed. (Author/MT)

  2. DNA adducts-chemical addons

    PubMed Central

    Rajalakshmi, T. R.; AravindhaBabu, N.; Shanmugam, K. T.; Masthan, K. M. K.

    2015-01-01

    DNA adduct is a piece of DNA covalently bond to a chemical (safrole, benzopyrenediol epoxide, acetaldehyde). This process could be the start of a cancerous cell. When a chemical binds to DNA, it gets damaged resulting in abnormal replication. This could be the start of a mutation and without proper DNA repair, this can lead to cancer. It is this chemical that binds with the DNA is our prime area of concern. Instead of performing the whole body analysis for diagnosing cancer, this test could be carried out for early detection of cancer. When scanning tunneling microscope is used, the DNA results can be obtained earlier. DNA adducts in scientific experiments are used as biomarkers. PMID:26015708

  3. Bioinspired catecholic copolymers for antifouling surface coatings.

    PubMed

    Cho, Joon Hee; Shanmuganathan, Kadhiravan; Ellison, Christopher J

    2013-05-01

    We report here a synthetic approach to prepare poly(methyl methacrylate)-polydopamine diblock (PMMA-PDA) and triblock (PDA-PMMA-PDA) copolymers combining mussel-inspired catecholic oxidative chemistry and atom transfer radical polymerization (ATRP). These copolymers display very good solubility in a range of organic solvents and also a broad band photo absorbance that increases with increasing PDA content in the copolymer. Spin-cast thin films of the copolymer were stable in water and showed a sharp reduction (by up to 50%) in protein adsorption compared to those of neat PMMA. Also the peak decomposition temperature of the copolymers was up to 43°C higher than neat PMMA. The enhanced solvent processability, thermal stability and low protein adsorption characteristics of this copolymer makes it attractive for variety of applications including antifouling coatings on large surfaces such as ship hulls, buoys, and wave energy converters.

  4. Urinary estrogens and estrogen metabolites and mammographic density in premenopausal women

    PubMed Central

    Bertrand, Kimberly A.; Eliassen, A. Heather; Hankinson, Susan E.; Gierach, Gretchen L.; Xu, Xia; Rosner, Bernard; Ziegler, Regina G.; Tamimi, Rulla M.

    2012-01-01

    Mammographic density is a strong and independent risk factor for breast cancer and is considered an intermediate marker of risk. The major predictors of premenopausal mammographic density, however, have yet to be fully elucidated. To test the hypothesis that urinary estrogen metabolism profiles are associated with mammographic density, we conducted a cross-sectional study among 352 premenopausal women in the Nurses’ Health Study II (NHSII). We measured average percent mammographic density using a computer-assisted method. In addition, we assayed 15 estrogens and estrogen metabolites (jointly termed EM) in luteal phase urine samples. We used multivariable linear regression to quantify the association of average percent density with quartiles of each individual EM as well as the sum of all EM (total EM), EM groups defined by metabolic pathway, and pathway ratios. In multivariable models controlling for body mass index (BMI) and other predictors of breast density, women in the top quartile of total EM had an average percent density 3.4 percentage points higher than women in the bottom quartile (95% confidence interval: −1.1, 8.0; p-trend=0.08). A non-significant positive association was noted for the 2-hydroxylation pathway catechols (breast density was 4.0 percentage points higher in top vs. bottom quartile; p-trend=0.06). In general, we observed no associations with parent estrogens or the 4- or 16-hydroxylation pathways or pathway ratios. These results suggest that urinary luteal estrogen profiles are not strongly associated with premenopausal mammographic density. If these profiles are associated with breast cancer risk, they may not act through influences on breast density. PMID:23053640

  5. Caffeine, coffee and tea intake and urinary estrogens and estrogen metabolites in premenopausal women

    PubMed Central

    Sisti, Julia S.; Hankinson, Susan E.; Caporaso, Neil E.; Gu, Fangyi; Tamimi, Rulla M.; Rosner, Bernard; Xu, Xia; Ziegler, Regina; Eliassen, A. Heather

    2015-01-01

    Background Prior studies have found weak inverse associations between breast cancer and caffeine and coffee intake, possibly mediated through their effects on sex hormones. Methods High-performance liquid chromatography/tandem mass spectrometry was used to quantify levels of 15 individual estrogens and estrogen metabolites (EM) among 587 premenopausal women in the Nurses’ Health Study II with mid-luteal phase urine samples and caffeine, coffee and/or tea intakes from self-reported food frequency questionnaires. Multivariate linear mixed models were used to estimate geometric means of individual EM, pathways and ratios by intake categories, and P-values for tests of linear trend. Results Compared to women in the lowest quartile of caffeine consumption, those in the top quartile had higher urinary concentrations of 16α-hydroxyestrone (28% difference; P-trend=0.01) and 16-epiestriol (13% difference; P-trend=0.04), and a decreased parent estrogens/2-, 4-, 16-pathway ratio (P-trend=0.03). Coffee intake was associated with higher 2-catechols, including 2-hydroxyestradiol (57% difference, ≥4 cups/day vs. ≤6 cups/week; P-trend=0.001) and 2-hydroxyestrone (52% difference; P-trend=0.001), and several ratio measures. Decaffeinated coffee was not associated with 2-pathway metabolism, but women in the highest (vs. lowest) category of intake (≥2 cups/day vs. ≤1–3 cups/month) had significantly lower levels of two 16-pathway metabolites, estriol (25% difference; P-trend=0.01) and 17-epiestriol (48% difference; Ptrend=0.0004). Tea intake was positively associated with 17-epiestriol (52% difference; Ptrend=0.01). Conclusion Caffeine and coffee intake were both associated with profiles of estrogen metabolism in premenopausal women. Impact Consumption of caffeine and coffee may alter patterns of premenopausal estrogen metabolism. PMID:26063478

  6. Estrogens, inflammation and cognition.

    PubMed

    Au, April; Feher, Anita; McPhee, Lucy; Jessa, Ailya; Oh, Soojin; Einstein, Gillian

    2016-01-01

    The effects of estrogens are pleiotropic, affecting multiple bodily systems. Changes from the body's natural fluctuating levels of estrogens, through surgical removal of the ovaries, natural menopause, or the administration of exogenous estrogens to menopausal women have been independently linked to an altered immune profile, and changes to cognitive processes. Here, we propose that inflammation may mediate the relationship between low levels of estrogens and cognitive decline. In order to determine what is known about this connection, we review the literature on the cognitive effects of decreased estrogens due to oophorectomy or natural menopause, decreased estrogens' role on inflammation--both peripherally and in the brain--and the relationship between inflammation and cognition. While this review demonstrates that much is unknown about the intersection between estrogens, cognition, inflammation, we propose that there is an important interaction between these literatures.

  7. Reactive oxygen species production by catechol stabilized copper nanoparticles.

    PubMed

    Chen, Cheng; Ahmed, Ishtiaq; Fruk, Ljiljana

    2013-12-01

    Stable Cu nanoparticles (NPs) prepared using catechol containing dopamine-based linkers could generate reactive oxygen species (ROS) that can activate peroxidase enzymes and catalyze the degradation of fluorescent dye pollutants.

  8. Speciation of oxaliplatin adducts with DNA nucleotides.

    PubMed

    Zayed, Aref; Jones, George D D; Reid, Helen J; Shoeib, Tamer; Taylor, Sarah E; Thomas, Anne L; Wood, Joanna P; Sharp, Barry L

    2011-10-01

    This paper describes a set of fast and selective high performance liquid chromatography (HPLC) methods coupled to electro-spray ionisation linear ion trap mass spectrometry (ESI-MS), sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS) and UV detection for in vitro studies of the bifunctional adducts of oxaliplatin with mono-nucleotides, di-nucleotides and cellular DNA. The stationary phases and the optimised conditions used for each separation are discussed. Interaction of oxaliplatin with A and G mono-nucleotides resulted in the formation of five bifunctional platinum diaminocyclohexane (DACHPt) adducts. These were two isomers of the A-DACHPt-A and A-DACHPt-G adducts, and one G-DACHPt-G adduct, as confirmed by MS/MS spectra obtained by collision induced dissociation. These adducts were also characterised by UV absorption data and SF-ICP-MS elemental (195)Pt and (31)P signals. Further, interaction of oxaliplatin with AG and GG di-nucleotides resulted in the formation of three adducts: DACHPt-GG and two isomers of the DACHPt-AG adduct, as confirmed by ESI-MS and the complementary data obtained by UV and SF-ICP-MS. Finally, a very sensitive LC-ICP-MS method for the quantification of oxaliplatin GG intra-strand adducts (DACHPt-GG) was developed and used for monitoring the in vitro formation and repair of these adducts in human colorectal cancer cells. The method detection limit was 0.14 ppb Pt which was equivalent to 0.22 Pt adduct per 10(6) nucleotides based on a 10 μg DNA sample. This detection limit makes this method suitable for in vivo assessment of DACHPt-GG adducts in patients undergoing oxaliplatin chemotherapy.

  9. The Use of Screen-Printed Electrodes in a Proof of Concept Electrochemical Estimation of Homocysteine and Glutathione in the Presence of Cysteine Using Catechol

    PubMed Central

    Lee, Patricia T.; Lowinsohn, Denise; Compton, Richard G.

    2014-01-01

    Screen printed electrodes were employed in a proof of concept determination of homocysteine and glutathione using electrochemically oxidized catechol via a 1,4-Michael addition reaction in the absence and presence of cysteine, and each other. Using cyclic voltammetry, the Michael reaction introduces a new adduct peak which is analytically useful in detecting thiols. The proposed procedure relies on the different rates of reaction of glutathione and homocysteine with oxidized catechol so that at fast voltage scan rates only homocysteine is detected in cyclic voltammetry. At slower scan rates, both glutathione and homocysteine are detected. The combination of the two sets of data provides quantification for homocysteine and glutathione. The presence of cysteine is shown not to interfere provided sufficient high concentrations of catechol are used. Calibration curves were determined for each homocysteine and glutathione detection; where the sensitivities are 0.019 μA·μM−1 and 0.0019 μA·μM−1 and limit of detections are ca. 1.2 μM and 0.11 μM for homocysteine and glutathione, respectively, within the linear range. This work presents results with potential and beneficial use in re-useable and/or disposable point-of-use sensors for biological and medical applications. PMID:24926695

  10. Assessment of genotoxicity of catecholics using impedimetric DNA-biosensor.

    PubMed

    Ensafi, Ali A; Amini, Maryam; Rezaei, B

    2014-03-15

    The potential toxicity of catecholics is a big concern, because the catechol-derived semiquinone radical after the oxidation of catechol (CA) can donate an H-atom to generate quinone, and during this process a superoxide anion radical may be produced. Considering the fact that catecholics are highly consumed in our daily life and some drugs also contain one or more CA moieties, we speculate that CA's toxicity might not be insurmountable. Therefore, finding approaches to investigate catecholics potential toxicity is of great significance. Here in, an electrochemical protocol for direct monitoring of genotoxicity of catecholics is described. CA encapsulated on MWCNTs (CA@MWCNT) through continuous cyclic voltammetric on the surface of pencil graphite electrode (PGE). Subsequently, a DNA functionalized biosensor (DNA/CA@MWCNT/PGE) was prepared and characterized for the detection and the investigation of DNA damage induced by radicals generated from catecholics. The change in the charge transfer resistance (Rct) after the incubation of the DNA biosensor in the damaging solution for a certain time was used as an indicator for DNA damage. Incubation of DNA-modified electrode with CA solution containing Cu(II), Cr(VI) and Fe(III) has been shown to result in oxidative damage to the DNA and change in the electrochemical properties. It was found that the presence of Cu(II), Cr(VI) and Fe(III) in solution caused damage to DNA. The inhibitory effect of glutathione and plumbagin on the CA-mediated DNA damage has also been investigated using the biosensor. The minimum concentration of the metal ions for CA induced DNA damage was investigated. Recognition of suitable matrixes for CA-mediated DNA damage can be assessed using proposed DNA biosensor. Such direct monitoring of the DNA damage holds great promise for designing new biosensors with modification of the biosensor with different damaging agents. PMID:24121207

  11. Synthesis, structure, spectra and reactivity of iron(III) complexes of imidazole and pyrazole containing ligands as functional models for catechol dioxygenases.

    PubMed

    Dhanalakshmi, Thirumanasekaran; Suresh, Eringathodi; Palaniandavar, Mallayan

    2009-10-21

    A series of new 1 : 1 iron(iii) complexes of the type [Fe()Cl(3)], where is a tridentate 3N donor ligand, has been isolated and studied as functional models for catechol dioxygenases. The ligands (1-methyl-1H-imidazol-2-ylmethyl)pyrid-2-ylmethyl-amine (), N,N-dimethyl-N'-(1-methyl-1H-imidazol-2-ylmethyl)ethane-1,2-diamine () and N-(1-methyl-1H-imidazol-2-ylmethyl)-N'-phenylethane-1,2-diamine () are linear while the ligands tris(1-pyrazolyl)methane (), tris(3,5-dimethyl-1-pyrazolyl)methane () and tris(3-iso-propylpyrazolyl)methane () are tripodal ones. All the complexes have been characterized by spectral and electrochemical methods. The X-ray crystal structure of the dinuclear catecholate adduct [Fe()(TCC)](2)O, where TCC(2-) is a tetrachlorocatecholate dianion, has been successfully determined. In this complex both the iron(iii) atoms are bridged by a mu-oxo group and each iron(iii) center possesses a distorted octahedral coordination geometry in which the ligand is facially coordinated and the remaining coordination sites are occupied by the TCC(2-) dianion. Spectral studies suggest that addition of a base like Et(3)N induces the mononuclear complex species [Fe()(TCC)Cl] to dimerize forming a mu-oxo-bridged complex. The spectral and electrochemical properties of the catecholate adducts of the complexes generated in situ reveal that a systematic variation in the ligand donor atom type significantly influences the Lewis acidity of the iron(iii) center and hence the interaction of the complexes with simple and substituted catechols. The 3,5-di-tert-butylcatecholate (DBC(2-)) adducts of the type [Fe()(DBC)Cl], where is a linear tridentate ligand (), undergo mainly oxidative intradiol cleavage of the catechol in the presence of dioxygen. Also, the extradiol-to-intradiol product selectivity (E : I) is enhanced upon removal of the coordinated chloride ion in these adducts to obtain [Fe()(DBC)(Sol)](+) and upon incorporating coordinated N-methylimidazolyl nitrogen in

  12. Crystal structures of human 108V and 108M catechol O-methyltransferase

    SciTech Connect

    Rutherford, K.; Le Trong, I.; Stenkamp, R.E.; Parson, W.W.

    2008-08-01

    Catechol O-methyltransferase (COMT) plays important roles in the metabolism of catecholamine neurotransmitters and catechol estrogens. The development of COMT inhibitors for use in the treatment of Parkinson's disease has been aided by crystallographic structures of the rat enzyme. However, the human and rat proteins have significantly different substrate specificities. Additionally, human COMT contains a common valine-methionine polymorphism at position 108. The methionine protein is less stable than the valine polymorph, resulting in decreased enzyme activity and protein levels in vivo. Here we describe the crystal structures of the 108V and 108M variants of the soluble form of human COMT bound with S-adenosylmethionine (SAM) and a substrate analog, 3,5-dinitrocatechol. The polymorphic residue 108 is located in the {alpha}5-{beta}3 loop, buried in a hydrophobic pocket {approx}16 {angstrom} from the SAM-binding site. The 108V and 108M structures are very similar overall [RMSD of C{sup {alpha}} atoms between two structures (C{sup {alpha}} RMSD) = 0.2 {angstrom}], and the active-site residues are superposable, in accord with the observation that SAM stabilizes 108M COMT. However, the methionine side chain is packed more tightly within the polymorphic site and, consequently, interacts more closely with residues A22 ({alpha}2) and R78 ({alpha}4) than does valine. These interactions of the larger methionine result in a 0.7-{angstrom} displacement in the backbone structure near residue 108, which propagates along {alpha}1 and {alpha}5 toward the SAM-binding site. Although the overall secondary structures of the human and rat proteins are very similar (C{sup {alpha}} RMSD = 0.4 {angstrom}), several nonconserved residues are present in the SAM-(I89M, I91M, C95Y) and catechol- (C173V, R201M, E202K) binding sites. The human protein also contains three additional solvent-exposed cysteine residues (C95, C173, C188) that may contribute to intermolecular disulfide bond

  13. Imidazolidinone adducts of peptides and hemoglobin

    SciTech Connect

    San George, R.C.; Hoberman, H.D.

    1986-05-01

    Acetaldehyde reacts selectively with the terminal amino groups of the ..cap alpha.. and ..beta.. chains of hemoglobin to form stable adducts, the structures of which, based on /sup 13/C NMR studies, are proposed to be diastereomeric 2-methyl imidazolidin-4-ones. In this scheme, acetaldelhyde forms a reversible Schiff base with the ..cap alpha..-amino groups of the polypeptide chains which cyclize with the amide nitrogen of the first peptide bond to form the stable imidazolidinone adducts. In support of this mechanism, the authors found that in following the reaction of the peptide val-gly-gly with (1,2-/sup 13/C) acetaldehyde, /sup 13/C NMR resonances attributed to a Schiff base (delta = 170 ppm) were observed which slowly disappeared prior to appearance of resonances from a pair of stable adducts (delta = 70 and 71 ppm) believed to be the diastereomeric imidazolidinones. Schiff base formation appeared to limit the overall rate. Tetraglycine reacted in a similar manner but with a resonance from a single stable adduct observed representing the enantiomeric imidazolidinone adducts of this peptide. Peptides with proline in position 2 should be incapable of forming imidazolidinones, and the authors found that ala-pro-gly did in fact fail to form a stable adduct with acetaldehyde. The 2-methyl imidazolidin-4-one adducts of hemoglobin may be useful in determining the contribution of the amino terminal groups to the structure and functional properties of hemoglobins.

  14. Estrogen and Bazedoxifene

    MedlinePlus

    ... menstrual periods become less frequent and stop and women may experience other symptoms and body changes). Estrogen and bazedoxifene tablets are also used to prevent osteoporosis (condition in which the bones ... and break easily) in women who have undergone menopause. Estrogen is in a ...

  15. Removal of arsenic compounds from spent catecholated polymer

    DOEpatents

    Fish, Richard H.

    1985-01-01

    Described is a process for removing arsenic from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic bound to it from contacting petroliferous liquid as described above and involves: a. treating said spent catecholated polystyrene, at a temperature in the range of about 20.degree. to 100.degree. C. with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10 and, b. separating the solids and liquids from each other. Preferably the regeneration treatment is in two steps wherein step (a) is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, steps (a) and (b) are repeated using a bicarbonate.

  16. Reactive oxygen species production by catechol stabilized copper nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Cheng; Ahmed, Ishtiaq; Fruk, Ljiljana

    2013-11-01

    Stable Cu nanoparticles (NPs) prepared using catechol containing dopamine-based linkers could generate reactive oxygen species (ROS) that can activate peroxidase enzymes and catalyze the degradation of fluorescent dye pollutants.Stable Cu nanoparticles (NPs) prepared using catechol containing dopamine-based linkers could generate reactive oxygen species (ROS) that can activate peroxidase enzymes and catalyze the degradation of fluorescent dye pollutants. Electronic supplementary information (ESI) available: Details of the synthesis of dopamine linkers and Cu NPs, peroxidase activity tests, H2O2 calibration and degradation tests for resorufin, RB and MB. See DOI: 10.1039/c3nr03563h

  17. Role of CYP1B1 in PAH-DNA adduct formation and breast cancer risk

    SciTech Connect

    Goth-Goldstein, Regine; Russell, Marion L.; Muller, A.P.; Caleffi, M.; Eschiletti, J.; Graudenz, M.; Sohn, Michael D.

    2010-04-01

    This study investigated the hypothesis that increased exposure to polycyclic aromatic hydrocarbons (PAHs) increases breast cancer risk. PAHs are products of incomplete burning of organic matter and are present in cigarette smoke, ambient air, drinking water, and diet. PAHs require metabolic transformation to bind to DNA, causing DNA adducts, which can lead to mutations and are thought to be an important pre-cancer marker. In breast tissue, PAHs appear to be metabolized to their cancer-causing form primarily by the cytochrome P450 enzyme CYP1B1. Because the genotoxic impact of PAH depends on their metabolism, we hypothesized that high CYP1B1 enzyme levels result in increased formation of PAH-DNA adducts in breast tissue, leading to increased development of breast cancer. We have investigated molecular mechanisms of the relationship between PAH exposure, CYP1B1 expression and breast cancer risk in a clinic-based case-control study. We collected histologically normal breast tissue from 56 women (43 cases and 13 controls) undergoing breast surgery and analyzed these specimens for CYP1B1 genotype, PAH-DNA adducts and CYP1B1 gene expression. We did not detect any difference in aromatic DNA adduct levels of cases and controls, only between smokers and non-smokers. CYP1B1 transcript levels were slightly lower in controls than cases, but the difference was not statistically significant. We found no correlation between the levels of CYP1B1 expression and DNA adducts. If CYP1B1 has any role in breast cancer etiology it might be through its metabolism of estrogen rather than its metabolism of PAHs. However, due to the lack of statistical power these results should be interpreted with caution.

  18. 40 CFR 721.10711 - Alkyl substituted catechol (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10711 Alkyl substituted catechol (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as...

  19. Catechol-O-methyltransferase val(158)met Polymorphism Interacts with Sex to Affect Face Recognition Ability.

    PubMed

    Lamb, Yvette N; McKay, Nicole S; Singh, Shrimal S; Waldie, Karen E; Kirk, Ian J

    2016-01-01

    The catechol-O-methyltransferase (COMT) val158met polymorphism affects the breakdown of synaptic dopamine. Consequently, this polymorphism has been associated with a variety of neurophysiological and behavioral outcomes. Some of the effects have been found to be sex-specific and it appears estrogen may act to down-regulate the activity of the COMT enzyme. The dopaminergic system has been implicated in face recognition, a form of cognition for which a female advantage has typically been reported. This study aimed to investigate potential joint effects of sex and COMT genotype on face recognition. A sample of 142 university students was genotyped and assessed using the Faces I subtest of the Wechsler Memory Scale - Third Edition (WMS-III). A significant two-way interaction between sex and COMT genotype on face recognition performance was found. Of the male participants, COMT val homozygotes and heterozygotes had significantly lower scores than met homozygotes. Scores did not differ between genotypes for female participants. While male val homozygotes had significantly lower scores than female val homozygotes, no sex differences were observed in the heterozygotes and met homozygotes. This study contributes to the accumulating literature documenting sex-specific effects of the COMT polymorphism by demonstrating a COMT-sex interaction for face recognition, and is consistent with a role for dopamine in face recognition. PMID:27445927

  20. Antiproliferative and Antiestrogenic Activities of Bonediol an Alkyl Catechol from Bonellia macrocarpa.

    PubMed

    Moo-Puc, Rosa; Caamal-Fuentes, Edgar; Peraza-Sánchez, Sergio R; Slusarz, Anna; Jackson, Glenn; Drenkhahn, Sara K; Lubahn, Dennis B

    2015-01-01

    The purpose of this study was to investigate antiproliferative activity of bonediol, an alkyl catechol isolated from the Mayan medicinal plant Bonellia macrocarpa. Bonediol was assessed for growth inhibition of androgen-sensitive (LNCaP), androgen-insensitive (PC-3), and metastatic androgen-insensitive (PC-3M) human prostate tumor cells; toxicity on normal cell line (HEK 293) was also evaluated. Hedgehog pathway was evaluated and competitive 3H-estradiol ligand binding assay was performed. Additionally, antioxidant activity on Nrf2-ARE pathway was evaluated. Bonediol induced a growth inhibition on prostate cancer cell lines (IC50 from 8.5 to 20.6 µM). Interestingly, bonediol binds to both estrogen receptors (ERα (2.5 µM) and ERβ (2.1 µM)) and displaces the native ligand E2 (17β-estradiol). No significant activity was found in the Hedgehog pathway. Additionally, activity of bonediol on Nrf2-ARE pathway suggested that bonediol could induce oxidative stress and activation of detoxification enzymes at 1 µM (3.8-fold). We propose that the compound bonediol may serve as a potential chemopreventive treatment with therapeutic potential against prostate cancer. PMID:26557704

  1. Catechol-O-methyltransferase val158met Polymorphism Interacts with Sex to Affect Face Recognition Ability

    PubMed Central

    Lamb, Yvette N.; McKay, Nicole S.; Singh, Shrimal S.; Waldie, Karen E.; Kirk, Ian J.

    2016-01-01

    The catechol-O-methyltransferase (COMT) val158met polymorphism affects the breakdown of synaptic dopamine. Consequently, this polymorphism has been associated with a variety of neurophysiological and behavioral outcomes. Some of the effects have been found to be sex-specific and it appears estrogen may act to down-regulate the activity of the COMT enzyme. The dopaminergic system has been implicated in face recognition, a form of cognition for which a female advantage has typically been reported. This study aimed to investigate potential joint effects of sex and COMT genotype on face recognition. A sample of 142 university students was genotyped and assessed using the Faces I subtest of the Wechsler Memory Scale – Third Edition (WMS-III). A significant two-way interaction between sex and COMT genotype on face recognition performance was found. Of the male participants, COMT val homozygotes and heterozygotes had significantly lower scores than met homozygotes. Scores did not differ between genotypes for female participants. While male val homozygotes had significantly lower scores than female val homozygotes, no sex differences were observed in the heterozygotes and met homozygotes. This study contributes to the accumulating literature documenting sex-specific effects of the COMT polymorphism by demonstrating a COMT-sex interaction for face recognition, and is consistent with a role for dopamine in face recognition. PMID:27445927

  2. Removal of estrogens and estrogenicity through drinking water treatment.

    PubMed

    Schenck, Kathleen; Rosenblum, Laura; Wiese, Thomas E; Wymer, Larry; Dugan, Nicholas; Williams, Daniel; Mash, Heath; Merriman, Betty; Speth, Thomas

    2012-03-01

    Estrogenic compounds have been shown to be present in surface waters, leading to concerns over their possible presence in finished drinking waters. In this work, two in vitro human cell line bioassays for estrogenicity were used to evaluate the removal of estrogens through conventional drinking water treatment using a natural water. Bench-scale studies utilizing chlorine, alum coagulation, ferric chloride coagulation, and powdered activated carbon (PAC) were conducted using Ohio River water spiked with three estrogens, 17β-estradiol, 17α-ethynylestradiol, and estriol. Treatment of the estrogens with chlorine, either alone or with coagulant, resulted in approximately 98% reductions in the concentrations of the parent estrogens, accompanied by formation of by-products. The MVLN reporter gene and MCF-7 cell proliferation assays were used to characterize the estrogenic activity of the water before and after treatment. The observed estrogenic activities of the chlorinated samples showed that estrogenicity of the water was reduced commensurate with removal of the parent estrogen. Therefore, the estrogen chlorination by-products did not contribute appreciably to the estrogenic activity of the water. Coagulation alone did not result in significant removals of the estrogens. However, addition of PAC, at a typical drinking water plant dose, resulted in removals ranging from approximately 20 to 80%. PMID:22361701

  3. SERMs attenuate estrogen-induced malignant transformation of human mammary epithelial cells by upregulating detoxification of oxidative metabolites.

    PubMed

    Hemachandra, L P Madhubhani P; Patel, Hitisha; Chandrasena, R Esala P; Choi, Jaewoo; Piyankarage, Sujeewa C; Wang, Shuai; Wang, Yijin; Thayer, Emily N; Scism, Robert A; Michalsen, Bradley T; Xiong, Rui; Siklos, Marton I; Bolton, Judy L; Thatcher, Gregory R J

    2014-05-01

    The risk of developing hormone-dependent cancers with long-term exposure to estrogens is attributed both to proliferative, hormonal actions at the estrogen receptor (ER) and to chemical carcinogenesis elicited by genotoxic, oxidative estrogen metabolites. Nontumorigenic MCF-10A human breast epithelial cells are classified as ER(-) and undergo estrogen-induced malignant transformation. Selective estrogen receptor modulators (SERM), in use for breast cancer chemoprevention and for postmenopausal osteoporosis, were observed to inhibit malignant transformation, as measured by anchorage-independent colony growth. This chemopreventive activity was observed to correlate with reduced levels of oxidative estrogen metabolites, cellular reactive oxygen species (ROS), and DNA oxidation. The ability of raloxifene, desmethylarzoxifene (DMA), and bazedoxifene to inhibit this chemical carcinogenesis pathway was not shared by 4-hydroxytamoxifen. Regulation of phase II rather than phase I metabolic enzymes was implicated mechanistically: raloxifene and DMA were observed to upregulate sulfotransferase (SULT 1E1) and glucuronidase (UGT 1A1). The results support upregulation of phase II metabolism in detoxification of catechol estrogen metabolites leading to attenuated ROS formation as a mechanism for inhibition of malignant transformation by a subset of clinically important SERMs.

  4. Sperm DNA oxidative damage and DNA adducts.

    PubMed

    Jeng, Hueiwang Anna; Pan, Chih-Hong; Chao, Mu-Rong; Lin, Wen-Yi

    2015-12-01

    The objective of this study was to investigate DNA damage and adducts in sperm from coke oven workers who have been exposed to polycyclic aromatic hydrocarbons. A longitudinal study was conducted with repeated measurements during spermatogenesis. Coke-oven workers (n=112) from a coke-oven plant served the PAH-exposed group, while administrators and security personnel (n=67) served the control. Routine semen parameters (concentration, motility, vitality, and morphology) were analyzed simultaneously; the assessment of sperm DNA integrity endpoints included DNA fragmentation, bulky DNA adducts, and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dGuo). The degree of sperm DNA fragmentation was measured using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay and sperm chromatin structure assay (SCSA). The PAH-exposed group had a significant increase in bulky DNA adducts and 8-oxo-dGuo compared to the control subjects (Ps=0.002 and 0.045, respectively). Coke oven workers' percentages of DNA fragmentation and denaturation from the PAH-exposed group were not significantly different from those of the control subjects (Ps=0.232 and 0.245, respectively). Routine semen parameters and DNA integrity endpoints were not correlated. Concentrations of 8-oxo-dGuo were positively correlated with percentages of DNA fragmentation measured by both TUNEL and SCSA (Ps=0.045 and 0.034, respectively). However, the concentrations of 8-oxo-dGuo and percentages of DNA fragmentation did not correlate with concentrations of bulky DNA adducts. In summary, coke oven workers with chronic exposure to PAHs experienced decreased sperm DNA integrity. Oxidative stress could contribute to the degree of DNA fragmentation. Bulky DNA adducts may be independent of the formation of DNA fragmentation and oxidative adducts in sperm. Monitoring sperm DNA integrity is recommended as a part of the process of assessing the impact of occupational and environmental toxins on sperm.

  5. Sperm DNA oxidative damage and DNA adducts.

    PubMed

    Jeng, Hueiwang Anna; Pan, Chih-Hong; Chao, Mu-Rong; Lin, Wen-Yi

    2015-12-01

    The objective of this study was to investigate DNA damage and adducts in sperm from coke oven workers who have been exposed to polycyclic aromatic hydrocarbons. A longitudinal study was conducted with repeated measurements during spermatogenesis. Coke-oven workers (n=112) from a coke-oven plant served the PAH-exposed group, while administrators and security personnel (n=67) served the control. Routine semen parameters (concentration, motility, vitality, and morphology) were analyzed simultaneously; the assessment of sperm DNA integrity endpoints included DNA fragmentation, bulky DNA adducts, and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dGuo). The degree of sperm DNA fragmentation was measured using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay and sperm chromatin structure assay (SCSA). The PAH-exposed group had a significant increase in bulky DNA adducts and 8-oxo-dGuo compared to the control subjects (Ps=0.002 and 0.045, respectively). Coke oven workers' percentages of DNA fragmentation and denaturation from the PAH-exposed group were not significantly different from those of the control subjects (Ps=0.232 and 0.245, respectively). Routine semen parameters and DNA integrity endpoints were not correlated. Concentrations of 8-oxo-dGuo were positively correlated with percentages of DNA fragmentation measured by both TUNEL and SCSA (Ps=0.045 and 0.034, respectively). However, the concentrations of 8-oxo-dGuo and percentages of DNA fragmentation did not correlate with concentrations of bulky DNA adducts. In summary, coke oven workers with chronic exposure to PAHs experienced decreased sperm DNA integrity. Oxidative stress could contribute to the degree of DNA fragmentation. Bulky DNA adducts may be independent of the formation of DNA fragmentation and oxidative adducts in sperm. Monitoring sperm DNA integrity is recommended as a part of the process of assessing the impact of occupational and environmental toxins on sperm

  6. Removal of Estrogens and Estrogenicity through Drinking Water Treatment

    EPA Science Inventory

    Estrogenic compounds have been shown to be present in surface waters, leading to concerns over their possible presence in finished drining waters. In this work, two in vitro human cell line bioassays for estrogenicity were used to evaluate the removal of estrogens through conven...

  7. Tyrosinase versus Catechol Oxidase: One Asparagine Makes the Difference.

    PubMed

    Solem, Even; Tuczek, Felix; Decker, Heinz

    2016-02-18

    Tyrosinases mediate the ortho-hydroxylation and two-electron oxidation of monophenols to ortho-quinones. Catechol oxidases only catalyze the oxidation of diphenols. Although it is of significant interest, the origin of the functional discrimination between tyrosinases and catechol oxidases has been unclear. Recently, it has been postulated that a glutamate and an asparagine bind and activate a conserved water molecule towards deprotonation of monophenols. Here we demonstrate for the first time that a polyphenoloxidase, which exhibits only diphenolase activity, can be transformed to a tyrosinase by mutation to introduce an asparagine. The asparagine and a conserved glutamate are necessary to properly orient the conserved water in order to abstract a proton from the monophenol. These results provide direct evidence for the crucial importance of a proton shuttle for tyrosinase activity of type 3 copper proteins, allowing a consistent understanding of their different chemical reactivities. PMID:26773413

  8. Nanofluidic redox cycling amplification for the selective detection of catechol.

    PubMed

    Wolfrum, Bernhard; Zevenbergen, Marcel; Lemay, Serge

    2008-02-15

    We have developed a chip-based nanofluidic device to amplify the electrochemical signal of catechols by orders of magnitude. The amplification is based on rapid redox cycling between plane parallel electrodes inside a nanochannel. We show that it is possible to monitor the signal of only a few hundred molecules residing in the active area of the nanofluidic sensor. Furthermore, due to the nanochannel design, the sensor is immune to interference by molecules undergoing irreversible redox reactions. We demonstrate the selectivity of the device by detecting catechol in the presence of ascorbic acid, whose oxidized form is only stable for a short time. The interference of ascorbic acid is usually a challenge in the detection of catecholamines in biological samples.

  9. Adsorption of catechol from aqueous solution by aminated hypercrosslinked polymers.

    PubMed

    Sun, Yue; Li, Xiao-Tao; Xu, Chao; Chen, Jin-Long; Li, Ai-Min; Zhang, Quan-Xing

    2005-01-01

    Adsorption of catechol from aqueous solution with the hypercrosslinked polymeric adsorbent NDA-100 and its derivatives AH-1, AH-2 and AH-3 aminated by dimethylamine, the commercial resin Amberlite XAD-4 and weakly basic anion exchanger resin D301 was compared. It was found that the aminated hypercrosslinked resins had the highest adsorption capacities among the tested polymers. The empirical Freundlich equation was successfully employed to describe the adsorption process. Specific surface area and micropore structure of the adsorbent, in company with tertiary amino groups on matrix affected the adsorption performance towards catechol. In addition, thermodynamic study was carried out to interpret the adsorption mechanism. Kinetic study testified that the tertiary amino groups on the polymer matrix could decrease the adsorption rate and increase the adsorption apparent activation energy.

  10. Low catechol-O-methyltransferase activity in a Saami population.

    PubMed

    Klemetsdal, B; Straume, B; Giverhaug, T; Aarbakke, J

    1994-01-01

    Catechol-O-methyltransferase (COMT) catalyzes the O-methylation of catechol hormones, neurotransmitters and certain drugs. It is subject to genetic polymorphism and ethnic differences. High red blood cell (RBC) COMT activity has been correlated with a poor response to levodopa treatment in Parkinson's disease. RBC COMT was determined in a Norwegian population (n = 213) of whom 115 were Saami (Laaps). The Saami had 16.5% lower RBC COMT activity compared to a non-Saami population sample from the northern part of Norway (n = 50), 13.9 vs. 16.4 units/ml RBC (U) (P = 0.04). This is the first report of any population with lower RBC COMT activity than a Caucasian population. A wide range of RBC COMT activities was found in the entire population examined (1.3-38.3 U).

  11. Brain catechol synthesis - Control by brain tyrosine concentration

    NASA Technical Reports Server (NTRS)

    Wurtman, R. J.; Larin, F.; Mostafapour, S.; Fernstrom, J. D.

    1974-01-01

    Brain catechol synthesis was estimated by measuring the rate at which brain dopa levels rose following decarboxylase inhibition. Dopa accumulation was accelerated by tyrosine administration, and decreased by treatments that lowered brain tyrosine concentrations (for example, intraperitoneal tryptophan, leucine, or parachlorophenylalanine). A low dose of phenylalanine elevated brain tyrosine without accelerating dopa synthesis. Our findings raise the possibility that nutritional and endocrine factors might influence brain catecholamine synthesis by controlling the availability of tyrosine.

  12. Platinum Nanoparticles: Efficient and Stable Catechol Oxidase Mimetics.

    PubMed

    Liu, Yi; Wu, Haohao; Chong, Yu; Wamer, Wayne G; Xia, Qingsu; Cai, Lining; Nie, Zhihong; Fu, Peter P; Yin, Jun-Jie

    2015-09-01

    Although enzyme-like nanomaterials have been extensively investigated over the past decade, most research has focused on the peroxidase-like, catalase-like, or SOD-like activity of these nanomaterials. Identifying nanomaterials having oxidase-like activities has received less attention. In this study, we demonstrate that platinum nanoparticles (Pt NPs) exhibit catechol oxidase-like activity, oxidizing polyphenols into the corresponding o-quinones. Four unique approaches are employed to demonstrate the catechol oxidase-like activity exerted by Pt NPs. First, UV-vis spectroscopy is used to monitor the oxidation of polyphenols catalyzed by Pt NPs. Second, the oxidized products of polyphenols are identified by ultrahigh-performance liquid chromatography (UHPLC) separation followed by high-resolution mass spectrometry (HRMS) identification. Third, electron spin resonance (ESR) oximetry techniques are used to confirm the O2 consumption during the oxidation reaction. Fourth, the intermediate products of semiquinone radicals formed during the oxidation of polyphenols are determined by ESR using spin stabilization. These results indicate Pt NPs possess catechol oxidase-like activity. Because polyphenols and related bioactive substances have been explored as potent antioxidants that could be useful for the prevention of cancer and cardiovascular diseases, and Pt NPs have been widely used in the chemical industry and medical science, it is essential to understand the potential effects of Pt NPs for altering or influencing the antioxidant activity of polyphenols.

  13. Platinum Nanoparticles: Efficient and Stable Catechol Oxidase Mimetics.

    PubMed

    Liu, Yi; Wu, Haohao; Chong, Yu; Wamer, Wayne G; Xia, Qingsu; Cai, Lining; Nie, Zhihong; Fu, Peter P; Yin, Jun-Jie

    2015-09-01

    Although enzyme-like nanomaterials have been extensively investigated over the past decade, most research has focused on the peroxidase-like, catalase-like, or SOD-like activity of these nanomaterials. Identifying nanomaterials having oxidase-like activities has received less attention. In this study, we demonstrate that platinum nanoparticles (Pt NPs) exhibit catechol oxidase-like activity, oxidizing polyphenols into the corresponding o-quinones. Four unique approaches are employed to demonstrate the catechol oxidase-like activity exerted by Pt NPs. First, UV-vis spectroscopy is used to monitor the oxidation of polyphenols catalyzed by Pt NPs. Second, the oxidized products of polyphenols are identified by ultrahigh-performance liquid chromatography (UHPLC) separation followed by high-resolution mass spectrometry (HRMS) identification. Third, electron spin resonance (ESR) oximetry techniques are used to confirm the O2 consumption during the oxidation reaction. Fourth, the intermediate products of semiquinone radicals formed during the oxidation of polyphenols are determined by ESR using spin stabilization. These results indicate Pt NPs possess catechol oxidase-like activity. Because polyphenols and related bioactive substances have been explored as potent antioxidants that could be useful for the prevention of cancer and cardiovascular diseases, and Pt NPs have been widely used in the chemical industry and medical science, it is essential to understand the potential effects of Pt NPs for altering or influencing the antioxidant activity of polyphenols. PMID:26305170

  14. Aerosol formation yields from the reaction of catechol with ozone

    NASA Astrophysics Data System (ADS)

    Coeur-Tourneur, Cécile; Tomas, Alexandre; Guilloteau, Angélique; Henry, Françoise; Ledoux, Frédéric; Visez, Nicolas; Riffault, Véronique; Wenger, John C.; Bedjanian, Yuri

    The formation of secondary organic aerosol from the gas-phase reaction of catechol (1,2-dihydroxybenzene) with ozone has been studied in two smog chambers. Aerosol production was monitored using a scanning mobility particle sizer and loss of the precursor was determined by gas chromatography and infrared spectroscopy, whilst ozone concentrations were measured using a UV photometric analyzer. The overall organic aerosol yield ( Y) was determined as the ratio of the suspended aerosol mass corrected for wall losses ( Mo) to the total reacted catechol concentrations, assuming a particle density of 1.4 g cm -3. Analysis of the data clearly shows that Y is a strong function of Mo and that secondary organic aerosol formation can be expressed by a one-product gas-particle partitioning absorption model. The aerosol formation is affected by the initial catechol concentration, which leads to aerosol yields ranging from 17% to 86%. The results of this work are compared to similar studies reported in the literature.

  15. Catechol-O-methyltransferase as a target for melanoma destruction?

    PubMed

    Smit, N P; Latter, A J; Naish-Byfield, S; Westerhof, W; Pavel, S; Riley, P A

    1994-08-17

    Catechols may interfere in melanogenesis by causing increased levels of toxic quinones. Several catechols and known inhibitors of the enzyme catechol-O-methyltransferase (COMT) were therefore tested for their toxicity towards a pigmented melanoma cell line, UCLA-SO-(M14). The inhibition of thymidine incorporation as a result of exposure to the compounds was measured. All agents were compared to 4-hydroxyanisole (4HA), a depigmenting agent extensively studied as an antimelanoma drug. The compounds were also tested on the epithelial cell line, CNCM-I-(221) in the presence and absence of tyrosinase. All the compounds were more effective than 4HA towards the M14-cells at either 10(-4) M or 10(-5) M. The toxicity of 4HA towards the 221-cells was shown to be completely dependent on the presence of tyrosinase. Effects of the test agents on the 221-cells were also observed in the absence of tyrosinase. Although some of them were shown to be good substrates for tyrosinase only small changes in toxicity were observed as a result of the presence of the enzyme in comparison with 4HA. No direct correlation of the toxicity of the agents and COMT inhibition was observed. The possible mode of action of the compounds through inhibition of COMT and interference in melanogenesis is discussed together with other possibilities and factors involved.

  16. Early changes in pulmonary gene expression following tobacco exposure shed light on the role of estrogen metabolism in lung carcinogenesis.

    PubMed

    Siegfried, Jill M

    2010-06-01

    This perspective on Meireles et al. (beginning on p. 707 in this issue of the journal) discusses the increasing evidence for the role of female steroid hormones in lung cancer development and progression. The novel work of Meireles et al. is the first evidence for the rapid upregulation by tobacco smoke of a key cytochrome P450 gene that can metabolize estrogens such as beta-estradiol to potentially carcinogenic catechol and quinine forms, as well as the first evidence for the colocalization of beta-estradiol and estrogen receptors in murine airway epithelium. Actions of estrogens that contribute to lung carcinogenesis, especially in the presence of tobacco smoke, may involve both reactive intermediates that damage DNA and steroid hormone receptor signaling that promotes growth.

  17. Effects of surface hydrophobicity on the catalytic iron ion retention in the active site of two catechol 1,2-dioxygenase isoenzymes.

    PubMed

    Di Nardo, Giovanna; Pessione, Enrica; Cavaletto, Maria; Anfossi, Laura; Vanni, Adriano; Briganti, Fabrizio; Giunta, Carlo

    2004-12-01

    The different behaviour of two isozymes (IsoA and IsoB) of catechol 1,2-dioxygenase (C 1,20) from Acinetobacter radioresistens S13 on a hydrophobic interaction, Phenyl-Sepharose chromatographic column, prompted us to investigate the role of superficial hydrophobicity on structural-functional aspects for such class of enzymes. The interaction of 8-anilino-1-naphtalenesulphonate (ANS), a fluorescent probe known to bind to hydrophobic sites in proteins, revealed that the two isoenzymes have a markedly different hydrophobicity degree although a similar number of hydrophobic superficial sites were estimated (2.65 for IsoA and 2.18 for IsoB). ANS is easily displaced by adding the substrates catechol or 3-methylcatechol to the adduct, suggesting that the binding sites are in the near surroundings of the catalytic clefts. The analysis of the hydropathy profiles and the possible superficial cavities allowed to recognize the most feasible region for ANS binding. The lower hydrophobicity detected in the near surroundings of the catalytic pocket of IsoB supports its peculiarity to lose the catalytic metal ions more easily than IsoA. As previously suggested for other metalloenzymes, the presence of more hydrophilic and/or smaller residues near to the active site of IsoB is expected to increase the metal ligands mobility thus increasing the metal ion dissociation rate constants, estimated to be 0.078 h(-1) and 0.670 h(-1) for IsoA and IsoB respectively.

  18. Macromolecular adducts caused by environmental chemicals.

    PubMed

    Neumann, H G; Albrecht, O; van Dorp, C; Zwirner-Baier, I

    1995-12-01

    We describe three biomonitoring studies in which hemoglobin (Hb) adducts were used as biochemical markers to assess indirectly the target dose of genotoxic chemicals. We monitored the exposure to 1,3-butadiene in occupationally exposed workers and in two control groups by analyzing the adducts formed by the reaction of the first activation product, butadiene monoepoxide, with the terminal valine of Hb; we also measured hydrolyzable adducts formed by the reaction of metabolically formed nitroso derivatives with Hb from five selected nitropolycyclic aromatic hydrocarbons (1-nitropyrene; 2-nitrofluorene, 3-nitrofluoranthrene, 6-nitrochrysene, and 9-nitrophenanthrene) in coke oven workers of different job categories and control workers of the same geographical area. We detected hydrolyzable adducts from monocyclic nitroarenes in blood from individuals living in a contaminated area where explosives had been produced and from controls. The contaminants considered were 2,4,6-trinitrotoluene; 2,4- and 2,6-dinitrotoluene; and 1,3-dinitrobenzene. Differences between groups were significant, but interindividual variation was great and back-ground exposures must be considered.

  19. The role of DNA methylation in catechol-enhanced erythroid differentiation of K562 cells

    SciTech Connect

    Li, Xiao-Fei; Wu, Xiao-Rong; Xue, Ming; Wang, Yan; Wang, Jie; Li, Yang; Suriguga,; Zhang, Guang-Yao; Yi, Zong-Chun

    2012-11-15

    Catechol is one of phenolic metabolites of benzene in vivo. Catechol is also widely used in pharmaceutical and chemical industries. In addition, fruits, vegetables and cigarette smoke also contain catechol. Our precious study showed that several benzene metabolites (phenol, hydroquinone, and 1,2,4-benzenetriol) inhibited erythroid differentiation of K562 cells. In present study, the effect of catechol on erythroid differentiation of K562 cells was investigated. Moreover, to address the role of DNA methylation in catechol-induced effect on erythroid differentiation in K562 cells, methylation levels of erythroid-specific genes were analyzed by Quantitative MassARRAY methylation analysis platform. Benzidine staining showed that exposure to catechol enhanced hemin-induced hemoglobin accumulation in K562 cells in concentration- and time-dependent manners. The mRNA expression of erythroid specific genes, including α-globin, β-globin, γ-globin, erythroid 5-aminolevulinate synthase, erythroid porphobilinogen deaminase, and transcription factor GATA-1 genes, showed a significant concentration-dependent increase in catechol-treated K562 cells. The exposure to catechol caused a decrease in DNA methylation levels at a few CpG sites in some erythroid specific genes including α-globin, β-globin and erythroid porphobilinogen deaminase genes. These results indicated that catechol improved erythroid differentiation potency of K562 cells at least partly via up-regulating transcription of some erythroid related genes, and suggested that inhibition of DNA methylation might be involved in up-regulated expression of some erythroid related genes. -- Highlights: ► Catechol enhanced hemin-induced hemoglobin accumulation. ► Exposure to catechol resulted in up-regulated expression of erythroid genes. ► Catechol reduced methylation levels at some CpG sites in erythroid genes.

  20. Biological degradation of catechol in wastewater using the sequencing continuous-inflow reactor (SCR).

    PubMed

    Aghapour, Ali Ahmad; Moussavi, Gholamreza; Yaghmaeian, Kamyar

    2013-05-24

    Catechol is used in many industries. It can be removed from wastewater by various methods but biological processes are the most superior and commonly used technology. The SCR is a modified form of SBR used to degrade catechol. The objective of this study was to investigate the performance of SCR for biodegradation and mineralization of catechol under various inlet concentrations (630-1500 mg/L) and hydraulic retention times (HRT) (18-9 h). This study used a bench scale SCR setup to test catechol degradation. The acclimation time of biomass for catechol at degradation at 630 mg/L was 41 d. The SCR operating cycle time was 6 h and the consecutive times taken for aerating, settling and decanting were 4, 1.5 and 0.5 h, respectively. This study investigated the effects of inlet catechol concentration (630-1560 mg/L) and HRT (18-9 h). The average catechol removal efficiencies in steady-state conditions of 630, 930, 12954 and 1559 mg/L of catechol were 98.5%, 98.5%, 98.2% and 96.9% in terms catechol and 97.8%, 97.7%, 96.4% and 94.3% for COD, respectively. SCR with acclimated biomasses could effectively remove the catechol and the corresponding COD from wastewater with concentrations of up to 1560, at the loading rate of 5.38 kg COD/m3.d and at a HRT of up to 13 h. The HRT was determined as an important variable affecting catechol removal from wastewater. Reducing the HRT to below 13 h led to reduced removal of catechol and COD.

  1. Identification of protein adduction using mass spectrometry: Protein adducts as biomarkers and predictors of toxicity mechanisms.

    PubMed

    Yang, Xiangkun; Bartlett, Michael G

    2016-03-15

    The determination of protein-xenobiotic adducts using mass spectrometry is an emerging area which allows detailed understanding of the underlying mechanisms involved in toxicity. These approaches can also be used to reveal potential biomarkers of exposure or toxic response. The following review covers studies of protein adducts resulting from exposure to a wide variety of xenobiotics including organophosphates, polycyclic aromatic hydrocarbons, acetaminophen, alkylating agents and other related compounds. PMID:26842586

  2. Estrogen receptors and endothelium.

    PubMed

    Arnal, Jean-François; Fontaine, Coralie; Billon-Galés, Audrey; Favre, Julie; Laurell, Henrik; Lenfant, Françoise; Gourdy, Pierre

    2010-08-01

    Estrogens, and in particular 17beta-estradiol (E2), play a pivotal role in sexual development and reproduction and are also implicated in a large number of physiological processes, including the cardiovascular system. Both acetylcholine-induced and flow-dependent vasodilation are preserved or potentiated by estrogen treatment in both animal models and humans. Indeed, E2 increases the endothelial production of nitric oxide and prostacyclin and prevents early atheroma through endothelial-mediated mechanisms. Furthermore, whereas it prevents endothelial activation, E2 potentiates the ability of several subpopulations of the circulating or resident immune cells to produce proinflammatory cytokines. The balance between these 2 actions could determine the final effect in a given pathophysiological process. E2 also promotes endothelial healing, as well as angiogenesis. Estrogen actions are essentially mediated by 2 molecular targets: estrogen receptor-alpha (ERalpha) and ERbeta. The analysis of mouse models targeted for ERalpha or ERbeta demonstrated a prominent role of ERalpha in vascular biology. ERalpha directly modulates transcription of target genes through 2 activation functions (AFs), AF-1 and AF-2. Interestingly, an AF-1-deficient ERalpha isoform can be physiologically expressed in the endothelium and appears sufficient to mediate most of the vasculoprotective actions of E2. In contrast, AF-1 is necessary for the E2 actions in reproductive targets. Thus, it appears conceivable to uncouple the vasculoprotective and sexual actions with appropriate selective ER modulators. PMID:20631350

  3. Antidepressant effects of estrogen.

    PubMed

    Price, W A; Giannini, A J

    1985-11-01

    The authors present a case report that provides support for a relationship between estrogen and the menstrual cycle on the 1 hand and affective disorders on the other. The patient in this case, a 35-year old woman, suffered from a rapid cycling affective disorder that was severely affected by her menstrual cycle and responded positively to oral contraceptives (OCs). The patient had a 24-year history of numerous manic and depressive episodes, the 1st of which coincided with menarche. She had noted that, 4 days before menses, she would experience symptoms of premenstrual tension syndrome (PMS) and often the onset of an affective episode. Treatment with a series of psychotropic agents had not been effective in controlling the number of episodes. However, the patient reported that there had been an 8-9-month period in the past when she had taken OCs and had fewer symptoms. Thus, the patient was placed on Ortho-Novum as well as imipramine. At the 9-month follow-up, she reported there had been no further episodes of depression or mania. The exact mechanism behind estrogen's psychotropic effect is unclear, although it increases the central availability of norepinephrine and induces changes in dopaminergic, noradrenergic, and serotonergic receptors. Beta-endorphin levels covary with estrogen levels, and estrogen seems to affect every major neurotransmitter system. The fact that estrogen has not consistently been shown to be effective in this regard may only signify the existence of a distinct subclass of affective disorders closely linked to the menstrual cycle. This subclass may have some type of dysfunction within the hypothalamic-pituitary-gonadal axis that contributes to mood swings.

  4. Estrogens and autoimmune diseases.

    PubMed

    Cutolo, Maurizio; Capellino, Silvia; Sulli, Alberto; Serioli, Bruno; Secchi, Maria Elena; Villaggio, Barbara; Straub, Rainer H

    2006-11-01

    Sex hormones are implicated in the immune response, with estrogens as enhancers at least of the humoral immunity and androgens and progesterone (and glucocorticoids) as natural immune-suppressors . Several physiological, pathological, and therapeutic conditions may change the serum estrogen milieu and/or peripheral conversion rate, including the menstrual cycle, pregnancy, postpartum period, menopause, being elderly, chronic stress, altered circadian rhythms, inflammatory cytokines, and use of corticosteroids, oral contraceptives, and steroid hormonal replacements, inducing altered androgen/estrogen ratios and related effects. In particular, cortisol and melatonin circadian rhythms are altered, at least in rheumatoid arthritis (RA), and partially involve sex hormone circadian synthesis and levels as well. Abnormal regulation of aromatase activity (i.e., increased activity) by inflammatory cytokine production (i.e., TNF-alpha, IL-1, and IL-6) may partially explain the abnormalities of peripheral estrogen synthesis in RA (i.e., increased availability of 17-beta estradiol and possible metabolites in synovial fluids) and in systemic lupus erythematosus, as well as the altered serum sex-hormone levels and ratio (i.e., decreased androgens and DHEAS). In the synovial fluids of RA patients, the increased estrogen concentration is observed in both sexes and is more specifically characterized by the hydroxylated forms, in particular 16alpha-hydroxyestrone, which is a mitogenic and cell proliferative endogenous hormone. Local effects of sex hormones in autoimmune rheumatic diseases seems to consist mainly in modulation of cell proliferation and cytokine production (i.e., TNF-alpha, Il-1, IL-12). In this respect, it is interesting that male patients with RA seem to profit more from anti-TNFalpha strategies than do female patients. PMID:17261796

  5. Breast Cancer Risk Reduction and Membrane-Bound Catechol O-Methyltransferase Genetic Polymorphisms

    PubMed Central

    Ji, Yuan; Olson, Janet; Zhang, Jianping; Hildebrandt, Michelle; Wang, Liewei; Ingle, James; Fredericksen, Zachary; Sellers, Thomas; Miller, William R.; Dixon, J. Michael; Brauch, Hiltrud; Eichelbaum, Michel; Justenhoven, Christina; Hamann, Ute; Ko, Yon; Brüning, Thomas; Chang-Claude, Jenny; Wang-Gohrke, Shan; Schaid, Daniel; Weinshilboum, Richard

    2008-01-01

    Catechol O-methyltransferase (COMT)-catalyzed methylation of catecholestrogens has been proposed to play a protective role in estrogen-induced genotoxic carcinogenesis. We have taken a comprehensive approach to test the hypothesis that genetic variation in COMT might influence breast cancer risk. Fifteen COMT SNPs selected on the basis of in-depth resequencing of the COMT gene were genotyped in 1482 DNA samples from a Mayo Clinic breast cancer case-control study. Two common SNPs in the distal promoter for membrane-bound (MB) COMT, rs2020917 and rs737865, were associated with breast cancer risk reduction in premenopausal women in the Mayo Clinic study, with allele-specific odds ratios of 0.70 (95% CI = 0.52–0.95) and 0.68 (95% CI = 0.51–0.92), respectively. These two SNPs were then subjected to functional genomic analysis and were genotyped in an additional 3683 DNA samples from two independent case-control studies (GENICA and GESBC). Functional genomic experiments showed that these SNPs could up-regulate transcription and that they altered DNA-protein binding patterns. Furthermore, substrate kinetic and exon array analyses suggested a role for MB-COMT in catecholestrogen inactivation. The GENICA results were similar to the Mayo case-control observations, with ORs of 0.85 (95% CI = 0.72–1.00) and 0.85 (95% CI = 0.72–1.01) for the two SNPs. No significant effect was observed in the GESBC study. These studies demonstrated that two SNPs in the COMT distal promoter were associated with breast cancer risk reduction in 2 of 3 case-control studies, compatible with the results of functional genomic experiments, suggesting a role for MB-COMT in breast cancer risk. PMID:18632656

  6. Vibrational energy redistribution in catechol during ultraviolet photolysis.

    PubMed

    King, Graeme A; Oliver, Thomas A A; Dixon, Richard N; Ashfold, Michael N R

    2012-03-14

    This article reports the striking interplay between the molecular structure and the photodissociation dynamics of catechol (a key dihydroxybenzene), identified using a combination of electronic spectroscopy, hydrogen (Rydberg) atom photofragment translational spectroscopy, density functional theory and second order approximate coupled cluster methods. We describe how the non-planar (C(1) symmetry) ← planar (C(s) symmetry) geometry change during S(1) (1(1)ππ*) ←S(0) excitation in catechol, as well as the presence of internal hydrogen bonding, can perturb the photodissociation dynamics relative to that of phenol (a monohydroxybenzene), particularly with respect to O-H bond fission via the lowest dissociative (1)πσ* state. For λ(phot) > 270 nm, O-H bond fission (of the non hydrogen bonded hydroxyl moiety) is deduced to proceed via H atom tunnelling from the photo-prepared 1(1)ππ* state into the lowest (1)πσ* state of the molecule. The vibrational energy distribution in the resulting catechoxyl product changes notably as λ(phot) is tuned on resonance with either the v' = 0, m(2)' = 1(+) or m(2)' = 2(+) torsional levels of the photo-prepared 1(1)ππ* state: the product state distribution is highly sensitive to the degree of OH torsional excitation (m(2)) prepared during photo-excitation. It is deduced that such torsional excitation can be redistributed very efficiently into ring puckering (and likely also in-plane ring stretch) vibrations as the molecule tunnels to its repulsive 1(1)πσ* state and dissociates. These observations can be rationalised by consideration of the photo-prepared nuclear wavefunctions. Analysis of the product vibrational energy distribution also reveals that the O-H bond strength of the non hydrogen bonded O-H moiety in catechol, D(0)(H-catechoxyl) ≤ 27 480 ± 50 cm(-1), ∼2500 cm(-1) lower than that of the sole O-H bond in bare phenol. As a consequence, the vertical excitation energy of the 1(1)πσ* state in catechol is

  7. Control of DNA hybridization with photocleavable adducts.

    PubMed

    Ghosn, Bilal; Haselton, Frederick R; Gee, Kyle R; Monroe, W Todd

    2005-01-01

    Previous reports have shown that 1-(4,5-dimethoxy-2-nitrophenyl)ethyl ester (DMNPE) adducts coupled to DNA plasmids block transcription in vitro and in vivo until removed with light. In this report, we explore the use of DMNPE to control DNA hybridization. We found that DMNPE-caged oligonucleotides have changed spectrophotometric and electrophoretic properties that can be restored with light exposure. Caged oligonucleotides have slower electrophoretic mobility than noncaged oligonucleotides and caged oligonucleotides exposed to light. Effects of caging on hybridization were assessed in a fluorescence-based assay using a 20mer caged DNA oligonucleotide complementary to a 30mer molecular beacon. Fluorescence results indicate that hybridization is reduced and subsequently restored by light. Subsequent gel shift assays confirmed these results. Hybridization activity of caged oligonucleotides with an average of 14-16 DMNPE adducts per oligonucleotide was 14% of noncaged control oligonucleotides and after 365 nm photolysis, increased to nearly 80% of controls. Spectrophotometric characterization of caged oligonucleotides exposed to light and then filtered to remove the released DMNPE adducts indicates two to four attached cage groups remaining following photoactivation. These results suggest that this light-based technology can be used as a tool for the spatial and temporal regulation of hybridization-based DNA bioactivity.

  8. Detection of Catechol by Potentiometric-Flow Injection Analysis in the Presence of Interferents

    ERIC Educational Resources Information Center

    Lunsford, Suzanne K.; Widera, Justyna; Zhang, Hong

    2007-01-01

    This article describes an undergraduate analytical chemistry experiment developed to teach instrumental lab skills while incorporating common interferents encountered in the real-world analysis of catechol. The lab technique incorporates potentiometric-flow injection analysis on a dibenzo-18-crown-6 dual platinum electrode to detect catechol in…

  9. Human DNA adduct measurements: state of the art.

    PubMed Central

    Poirier, M C; Weston, A

    1996-01-01

    Human DNA adduct formation (covalent modification of DNA with chemical carcinogens) is a promising biomarker for elucidating the molecular epidemiology of cancer. Classes of compounds for which human DNA adducts have been observed include polycyclic aromatic hydrocarbons (PAHs), nitrosamines, mycotoxins, aromatic amines, heterocyclic amines, ultraviolet light, and alkylating cancer chemotherapeutic agents. Most human DNA adduct exposure monitoring has been performed with either 32P-postlabeling or immunoassays, neither of which is able to chemically characterize specific DNA adducts. Recently developed combinations of methods with chemical and physical end points have allowed identification of specific adducts in human tissues. Studies are presented that demonstrate that high ambient levels of benzo[a]pyrene are associated with high levels of DNA adducts in human blood cell DNA and that the same DNA adduct levels drop when the ambient PAH levels decrease significantly. DNA adduct dosimetry, which has been achieved with some dietary carcinogens and cancer chemotherapeutic agents, is described, as well as studies correlating DNA adducts with other biomarkers. It is likely that some toxic, noncarcinogenic compounds may have genotoxic effects, including oxidative damage, and that adverse health outcomes other than cancer may be correlated with DNA adduct formation. The studies presented here may serve as useful prototypes for exploration of other toxicological end points. PMID:8933030

  10. Improved performance of protected catecholic polysiloxanes for bio-inspired wet adhesion to surface oxides

    PubMed Central

    Heo, Jinhwa; Kang, Taegon; Jang, Se Gyu; Hwang, Dong Soo; Spruell, Jason M.; Killops, Kato L.; Waite, J. Herbert; Hawker, Craig J.

    2012-01-01

    A facile synthetic strategy for introducing catecholic moieties into polymeric materials based on a readily available precursor – eugenol – and efficient chemistries – tris(pentafluorophenyl)borane catalyzed silation and thiol-ene coupling is reported. Silyl-protection is shown to be critical for the oxidative stability of catecholic moieties during synthesis and processing which allows functionalized polysiloxane derivatives to be fabricated into 3-D microstructures as well as 2-D patterned surfaces. Deprotection gives stable catechol surfaces with adhesion to a variety of oxide surfaces being precisely tuned by the level of catechol incorporation. The advantage of silyl-protection for catechol functionalized polysiloxanes is demonstrated and represents a promising and versatile new platform for underwater surface treatments. PMID:23181614

  11. Synthesis of tripodal catecholates and their immobilization on zinc oxide nanoparticles

    PubMed Central

    Klitsche, Franziska; Ramcke, Julian; Migenda, Julia; Hensel, Andreas; Vossmeyer, Tobias; Weller, Horst

    2015-01-01

    Summary A common approach to generate tailored materials and nanoparticles (NPs) is the formation of molecular monolayers by chemisorption of bifunctional anchor molecules. This approach depends critically on the choice of a suitable anchor group. Recently, bifunctional catecholates, inspired by mussel-adhesive proteins (MAPs) and bacterial siderophores, have received considerable interest as anchor groups for biomedically relevant metal surfaces and nanoparticles. We report here the synthesis of new tripodal catecholates as multivalent anchor molecules for immobilization on metal surfaces and nanoparticles. The tripodal catecholates have been conjugated to various effector molecules such as PEG, a sulfobetaine and an adamantyl group. The potential of these conjugates has been demonstrated with the immobilization of tripodal catecholates on ZnO NPs. The results confirmed a high loading of tripodal PEG-catecholates on the particles and the formation of stable PEG layers in aqueous solution. PMID:26124871

  12. Concerted actions of the catechol O-methyltransferase and the cytosolic sulfotransferase SULT1A3 in the metabolism of catecholic drugs.

    PubMed

    Kurogi, Katsuhisa; Alazizi, Adnan; Liu, Ming-Yih; Sakakibara, Yoichi; Suiko, Masahito; Sugahara, Takuya; Liu, Ming-Cheh

    2012-11-01

    Catecholic drugs had been reported to be metabolized through conjugation reactions, particularly methylation and sulfation. Whether and how these two Phase II conjugation reactions may occur in a concerted manner, however, remained unclear. The current study was designed to investigate the methylation and/or sulfation of five catecholic drugs. Analysis of the spent media of HepG2 cells metabolically labeled with [(35)S]sulfate in the presence of individual catecholic drugs revealed the presence of two [(35)S]sulfated metabolites for dopamine, epinephrine, isoproterenol, and isoetharine, but only one [(35)S]sulfated metabolite for apomorphine. Further analyses using tropolone, a catechol O-methyltransferase (COMT) inhibitor, indicated that one of the two [(35)S]sulfated metabolites of dopamine, epinephrine, isoproterenol, and isoetharine was a doubly conjugated (methylated and sulfated) product, since its level decreased proportionately with increasing concentrations of tropolone added to the labeling media. Moreover, while the inhibition of methylation resulted in a decrease of the total amount of [(35)S]sulfated metabolites, sulfation appeared to be capable of compensating the suppressed methylation in the metabolism of these four catecholic drugs. A two-stage enzymatic assay showed the sequential methylation and sulfation of dopamine, epinephrine, isoproterenol, and isoetharine mediated by, respectively, the COMT and the cytosolic sulfotransferase SULT1A3. Collectively, the results from the present study implied the concerted actions of the COMT and SULT1A3 in the metabolism of catecholic drugs.

  13. Exercise, Eating, Estrogen, and Osteoporosis.

    ERIC Educational Resources Information Center

    Brown, Jim

    1986-01-01

    Osteoporosis affects millions of people, especially women. Three methods for preventing or managing osteoporosis are recommended: (1) exercise; (2) increased calcium intake; and (3) estrogen replacement therapy. (CB)

  14. Mapping the conformational space accessible to catechol-O-methyltransferase.

    PubMed

    Ehler, Andreas; Benz, Jörg; Schlatter, Daniel; Rudolph, Markus G

    2014-08-01

    Methylation catalysed by catechol-O-methyltransferase (COMT) is the main pathway of catechol neurotransmitter deactivation in the prefrontal cortex. Low levels of this class of neurotransmitters are held to be causative of diseases such as schizophrenia, depression and Parkinson's disease. Inhibition of COMT may increase neurotransmitter levels, thus offering a route for treatment. Structure-based drug design hitherto seems to be based on the closed enzyme conformation. Here, a set of apo, semi-holo, holo and Michaelis form crystal structures are described that define the conformational space available to COMT and that include likely intermediates along the catalytic pathway. Domain swaps and sizeable loop movements around the active site testify to the flexibility of this enzyme, rendering COMT a difficult drug target. The low affinity of the co-substrate S-adenosylmethionine and the large conformational changes involved during catalysis highlight significant energetic investment to achieve the closed conformation. Since each conformation of COMT is a bona fide target for inhibitors, other states than the closed conformation may be promising to address. Crystallographic data for an alternative avenue of COMT inhibition, i.e. locking of the apo state by an inhibitor, are presented. The set of COMT structures may prove to be useful for the development of novel classes of inhibitors.

  15. Mapping the conformational space accessible to catechol-O-methyltransferase.

    PubMed

    Ehler, Andreas; Benz, Jörg; Schlatter, Daniel; Rudolph, Markus G

    2014-08-01

    Methylation catalysed by catechol-O-methyltransferase (COMT) is the main pathway of catechol neurotransmitter deactivation in the prefrontal cortex. Low levels of this class of neurotransmitters are held to be causative of diseases such as schizophrenia, depression and Parkinson's disease. Inhibition of COMT may increase neurotransmitter levels, thus offering a route for treatment. Structure-based drug design hitherto seems to be based on the closed enzyme conformation. Here, a set of apo, semi-holo, holo and Michaelis form crystal structures are described that define the conformational space available to COMT and that include likely intermediates along the catalytic pathway. Domain swaps and sizeable loop movements around the active site testify to the flexibility of this enzyme, rendering COMT a difficult drug target. The low affinity of the co-substrate S-adenosylmethionine and the large conformational changes involved during catalysis highlight significant energetic investment to achieve the closed conformation. Since each conformation of COMT is a bona fide target for inhibitors, other states than the closed conformation may be promising to address. Crystallographic data for an alternative avenue of COMT inhibition, i.e. locking of the apo state by an inhibitor, are presented. The set of COMT structures may prove to be useful for the development of novel classes of inhibitors. PMID:25084335

  16. Analgesic use and patterns of estrogen metabolism in premenopausal women.

    PubMed

    Fortner, Renée T; Oh, Hannah; Daugherty, Sarah E; Xu, Xia; Hankinson, Susan E; Ziegler, Regina G; Eliassen, A Heather

    2014-04-01

    Analgesic use has been hypothesized to reduce the risk of some cancers, with inverse associations between analgesics and colon cancer, and suggestive inverse associations for breast cancer. Estrogen metabolites (EM) have genotoxic and estrogenic potential; genotoxicity may differ by hydroxylation pathway. Analgesic use may impact patterns of estrogen metabolism; effects of analgesics on disease risk could be mediated through these patterns. We conducted a cross-sectional study among 603 premenopausal women in the Nurses' Health Study II. Frequency of aspirin, non-aspirin nonsteroidal anti-inflammatory drugs (NSAIDs), and acetaminophen use was reported via questionnaire; average frequency in 1997 and 1999 was calculated. Women provided urine samples between 1996 and 1999, collected during the mid-luteal phase of the menstrual cycle. Urinary EM were quantified using high-performance liquid chromatography-tandem mass spectrometry. We observed no association between analgesic use and estradiol, estrone, or specific pathways of estrogen metabolism. Women reporting more frequent aspirin use had lower methylated 2-catechols (e.g., 2-hydroxyestrone-3-methyl ether, 2+ days/week vs. non-use: 0.95 vs. 1.21 pmol/mg creatinine; p difference = 0.01, p trend = 0.07). Non-aspirin NSAID use was positively associated with 17-epiestriol (4+ days/week vs. non-use: 2.48 vs. 1.52 pmol/mg creatinine; p difference = 0.01, p trend = 0.11). Acetaminophen use was positively associated with total EM (2+ days/week vs. non-use: 236 vs. 198 pmol/mg creatinine; p difference = 0.02, p trend = 0.11), 2-hydroxyestrone-3-methyl ether (1.6 vs. 1.1 pmol/mg creatinine; p difference < 0.01, p trend = 0.02), and 16α-hydroxyestrone (17 vs. 12 pmol/mg creatinine; p difference = 0.01, p trend = 0.05). This study provides the first assessment of analgesic use and patterns of estrogen metabolism in women. While we observed some associations between analgesics and

  17. A stable epoxide as a potential endogenous estrogen metabolite: Possible significance in breast cancer?

    PubMed

    Raeside, James I

    2016-06-01

    Epoxides as reactive intermediates of estrogen metabolism have been considered to be potential precursors of the 2- and 4-hydroxy, catechol estrogens and even to be mutagenic/carcinogenic agents themselves. The labile nature of the intermediates has made proof of their existence difficult in natural biological conditions. In our studies on estrogen metabolism in vitro, in various tissues from several laboratory and domestic species, there was chromatographic evidence of formation of a stable estrogen metabolite that could be seen after incubation with radiolabeled estrone, but not with unlabeled substrate. Investigation with acid treatment of the metabolite yielded material detected as 6-hydroxy-estrone-suggesting the presence of an additional oxygen atom in the molecule. An identification of the "unknown compound" has not yet been made but, with this evidence, the properties revealed so far can best be met by assuming the presence of 5,6-epoxy-estrone. The recent favorable reports on the role of 5α,6α-epoxy-cholesterol in breast cancer has led to the hypothesis that the formation of a similar, stable epoxide of an estrogen could potentially be a compound of interest. If a metabolic pathway from estrone to 6-hydroxy-estrone through a stable epoxide has indeed been observed, it would suggest that identifying and screening for the enzymes responsible for its production, as opposed to those generating the catecholestrogens, could provide valuable information in relation to breast cancer. The balance in production of estrogen epoxides could be a key factor in determining normal health or risk of tumor development. PMID:27142140

  18. Protein modification by acrolein: Formation and stability of cysteine adducts

    PubMed Central

    Cai, Jian; Bhatnagar, Aruni; Pierce, William M.

    2010-01-01

    The toxicity of the ubiquitous pollutant and endogenous metabolite, acrolein, is due in part to covalent protein modifications. Acrolein reacts readily with protein nucleophiles via Michael addition and Schiff base formation. Potential acrolein targets in protein include the nucleophilic side chains of cysteine, histidine, and lysine residues as well as the free amino terminus of proteins. Although cysteine is the most acrolein-reactive residue, cysteine-acrolein adducts are difficult to identify in vitro and in vivo. In this study, model peptides with cysteine, lysine, and histidine residues were used to examine the reactivity of acrolein. Results from these experiments show that acrolein reacts rapidly with cysteine residues through Michael addition to form M+56 Da adducts. These M+56 adducts are, however, not stable, even though spontaneous dissociation of the adduct is slow. Further studies demonstrated that when acrolein and model peptides are incubated at physiological pH and temperature, the M+56 adducts decreased gradually accompanied by the increase of M+38 adducts, which are formed from intra-molecular Schiff base formation. Adduct formation with the side chains of other amino acid residues (lysine and histidine) was much slower than cysteine and required higher acrolein concentration. When cysteine residues were blocked by reaction with iodoacetamide and higher concentrations of acrolein were used, adducts of the N-terminal amino group or histidyl residues were formed but lysine adducts were not detected. Collectively, these data demonstrate that acrolein reacts avidly with protein cysteine residues and that the apparent loss of protein-acrolein Michael adducts over time may be related to the appearance of a novel (M+38) adduct. These findings may be important in identification of in vivo adducts of acrolein with protein cysteine residues. PMID:19231900

  19. What predicts the first peak of the knee adduction moment?

    PubMed Central

    Schmitz, Anne; Noehren, Brian

    2014-01-01

    Introduction The first peak of the knee adduction moment curve during walking has been shown to be a good clinical surrogate measure of medial tibiofemoral joint loading and osteoarthritis. Defining the relative contributions of the variables that dictate the knee adduction moment, such as center of mass, center of pressure, vertical ground reaction force, and knee adduction angle (i.e. lower limb alignment), has not been formally investigated within the same cohort of individuals. Purpose Therefore, the goal of this study was to determine which of these variables is the biggest determinant of the first peak of knee adduction moment curve. Methods Instrumented gait analysis was collected for 30 individuals. Variables significantly correlated with the peak knee adduction moment were input into a stepwise multi-variable linear regression model. Results The knee adduction angle predicted 58% of the variance in the first peak knee adduction moment and the vertical ground reaction force magnitude predicted the second most variance (20%). Conclusions The most effective way to modify the peak knee adduction moment may be to change the knee adduction angle (e.g. offloader brace), followed by changing the vertical magnitude of the ground reaction force (e.g. cane use). PMID:25127390

  20. Quantitation of carcinogen bound protein adducts by fluorescence measurements

    NASA Astrophysics Data System (ADS)

    Gan, Liang-Shang; Otteson, Michael S.; Doxtader, Mark M.; Skipper, Paul L.; Dasari, Ramachandra R.; Tannenbaum, Steven R.

    1989-01-01

    A highly significant correlation of aflatoxin B 1 serum albumin adduct level with daily aflatoxin B 1 intake was observed in a molecular epidemiological study of aflatoxin carcinogenesis which used conventional fluorescence spectroscopy methods for adduct quantitation. Synchronous fluorescence spectroscopy and laser induced fluorescence techniques have been employed to quantitate antibenzo[ a]pyrene diol epoxide derived globin peptide adducts. Fast and efficient methods to isolate the peptide adducts as well as eliminate protein fluorescence background are described. A detection limit of several femtomoles has been achieved. Experimental and technical considerations of low temperature synchronous fluorescence spectroscopy and fluorescence line narrowing to improve the detection sensitivities are also presented.

  1. No association between germline variation in catechol-O-methyltransferase and colorectal cancer survival in postmenopausal women

    PubMed Central

    Passarelli, Michael N.; Newcomb, Polly A.; Makar, Karen W.; Burnett-Hartman, Andrea N.; Phipps, Amanda I.; David, Sean P.; Hsu, Li; Harrison, Tabitha A.; Hutter, Carolyn M.; Duggan, David J.; White, Emily; Chan, Andrew T.; Peters, Ulrike

    2013-01-01

    Objective Sex-steroid hormones play a role in colorectal cancer (CRC) development, but little is known about their influence on tumor progression and metastasis. Because catechol-O-methyltransferase activity (COMT; 22q11.21) is an important component of estrogen-mediated carcinogenesis, we hypothesized that germline variation in COMT may be associated with CRC survival. Methods We identified 10 single-nucleotide polymorphisms (SNPs) that tagged variation across both isoforms of COMT in 2,458 women with CRC from the Nurses’ Health Study (NHS), Postmenopausal Hormones Supplementary Study to the Colon Cancer Family Registry (PMH-CCFR), VITamins And Lifestyle (VITAL) Study, and Women’s Health Initiative (WHI). All four studies participate in the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO). Results Over a median follow-up of 7 years across all studies, there were 799 deaths, including 566 from CRC. Accounting for multiple comparisons, no associations between the SNPs and CRC-specific or overall survival reached statistical significance, including the well-characterized Val108/158Met polymorphism (rs4680; hazard ratio per minor allele [HR], 1.04; 95% confidence interval [CI], 0.92–1.17 for CRC-specific survival and 1.01; 0.90–1.14 for overall survival). Conclusions In this large study of women with CRC, we found no evidence that common inherited variation in COMT is associated with survival-time after diagnosis. PMID:23880798

  2. Bio-inspired adhesive catechol-conjugated chitosan for biomedical applications: A mini review.

    PubMed

    Ryu, Ji Hyun; Hong, Seonki; Lee, Haeshin

    2015-11-01

    The development of adhesive materials, such as cyanoacrylate derivatives, fibrin glues, and gelatin-based adhesives, has been an emerging topic in biomaterial science because of the many uses of these materials, including in wound healing patches, tissue sealants, and hemostatic materials. However, most bio-adhesives exhibit poor adhesion to tissue and related surfaces due to the presence of body fluid. For a decade, studies have aimed at addressing this issue by developing wet-resistant adhesives. Mussels demonstrate robust wet-resistant adhesion despite the ceaseless waves at seashores, and mussel adhesive proteins play a key role in this adhesion. Adhesive proteins located at the distal end (i.e., those that directly contact surfaces) are composed of nearly 60% of amino acids called 3,4-dihydroxy-l-phenylalanine (DOPA), lysine, and histidine, which contain side chains of catechol, primary amines, and secondary amines, respectively. Inspired by the abundant catecholamine in mussel adhesive proteins, researchers have developed various types of polymeric mimics, such as polyethylenimine-catechol, chitosan-catechol, and other related catecholic polymers. Among them, chitosan-catechol is a promising adhesive polymer for biomedical applications. The conjugation of catechol onto chitosan dramatically increases its solubility from zero to nearly 60mg/mL (i.e., 6% w/v) in pH 7 aqueous solutions. The enhanced solubility maximizes the ability of catecholamine to behave similar to mussel adhesive proteins. Chitosan-catechol is biocompatible and exhibits excellent hemostatic ability and tissue adhesion, and thus, chitosan-catechol will be widely used in a variety of medical settings in the future. This review focuses on the various aspects of chitosan-catechol, including its (1) preparation methods, (2) physicochemical properties, and (3) current applications.

  3. Bio-inspired adhesive catechol-conjugated chitosan for biomedical applications: A mini review.

    PubMed

    Ryu, Ji Hyun; Hong, Seonki; Lee, Haeshin

    2015-11-01

    The development of adhesive materials, such as cyanoacrylate derivatives, fibrin glues, and gelatin-based adhesives, has been an emerging topic in biomaterial science because of the many uses of these materials, including in wound healing patches, tissue sealants, and hemostatic materials. However, most bio-adhesives exhibit poor adhesion to tissue and related surfaces due to the presence of body fluid. For a decade, studies have aimed at addressing this issue by developing wet-resistant adhesives. Mussels demonstrate robust wet-resistant adhesion despite the ceaseless waves at seashores, and mussel adhesive proteins play a key role in this adhesion. Adhesive proteins located at the distal end (i.e., those that directly contact surfaces) are composed of nearly 60% of amino acids called 3,4-dihydroxy-l-phenylalanine (DOPA), lysine, and histidine, which contain side chains of catechol, primary amines, and secondary amines, respectively. Inspired by the abundant catecholamine in mussel adhesive proteins, researchers have developed various types of polymeric mimics, such as polyethylenimine-catechol, chitosan-catechol, and other related catecholic polymers. Among them, chitosan-catechol is a promising adhesive polymer for biomedical applications. The conjugation of catechol onto chitosan dramatically increases its solubility from zero to nearly 60mg/mL (i.e., 6% w/v) in pH 7 aqueous solutions. The enhanced solubility maximizes the ability of catecholamine to behave similar to mussel adhesive proteins. Chitosan-catechol is biocompatible and exhibits excellent hemostatic ability and tissue adhesion, and thus, chitosan-catechol will be widely used in a variety of medical settings in the future. This review focuses on the various aspects of chitosan-catechol, including its (1) preparation methods, (2) physicochemical properties, and (3) current applications. PMID:26318801

  4. Selective Estrogen Receptor Modulators.

    PubMed

    An, Ki-Chan

    2016-08-01

    Selective estrogen receptor modulators (SERMs) are now being used as a treatment for breast cancer, osteoporosis and postmenopausal symptoms, as these drugs have features that can act as an estrogen agonist and an antagonist, depending on the target tissue. After tamoxifen, raloxifene, lasofoxifene and bazedoxifene SERMs have been developed and used for treatment. The clinically decisive difference among these drugs (i.e., the key difference) is their endometrial safety. Compared to bisphosphonate drug formulations for osteoporosis, SERMs are to be used primarily in postmenopausal women of younger age and are particularly recommended if there is a family history of invasive breast cancer, as their use greatly reduces the incidence of this type of cancer in women. Among the above mentioned SERMs, raloxifene has been widely used in prevention and treatment of postmenopausal osteoporosis and vertebral compression fractures, and clinical studies are now underway to test the comparative advantages of raloxifene with those of bazedoxifene, a more recently developed SERM. Research on a number of adverse side effects of SERM agents is being performed to determine the long-term safety of this class of compouds for treatment of osteoporosis. PMID:27559463

  5. Selective Estrogen Receptor Modulators

    PubMed Central

    2016-01-01

    Selective estrogen receptor modulators (SERMs) are now being used as a treatment for breast cancer, osteoporosis and postmenopausal symptoms, as these drugs have features that can act as an estrogen agonist and an antagonist, depending on the target tissue. After tamoxifen, raloxifene, lasofoxifene and bazedoxifene SERMs have been developed and used for treatment. The clinically decisive difference among these drugs (i.e., the key difference) is their endometrial safety. Compared to bisphosphonate drug formulations for osteoporosis, SERMs are to be used primarily in postmenopausal women of younger age and are particularly recommended if there is a family history of invasive breast cancer, as their use greatly reduces the incidence of this type of cancer in women. Among the above mentioned SERMs, raloxifene has been widely used in prevention and treatment of postmenopausal osteoporosis and vertebral compression fractures, and clinical studies are now underway to test the comparative advantages of raloxifene with those of bazedoxifene, a more recently developed SERM. Research on a number of adverse side effects of SERM agents is being performed to determine the long-term safety of this class of compouds for treatment of osteoporosis. PMID:27559463

  6. Quinone Reductase 2 Is a Catechol Quinone Reductase

    SciTech Connect

    Fu, Yue; Buryanovskyy, Leonid; Zhang, Zhongtao

    2008-09-05

    The functions of quinone reductase 2 have eluded researchers for decades even though a genetic polymorphism is associated with various neurological disorders. Employing enzymatic studies using adrenochrome as a substrate, we show that quinone reductase 2 is specific for the reduction of adrenochrome, whereas quinone reductase 1 shows no activity. We also solved the crystal structure of quinone reductase 2 in complexes with dopamine and adrenochrome, two compounds that are structurally related to catecholamine quinones. Detailed structural analyses delineate the mechanism of quinone reductase 2 specificity toward catechol quinones in comparison with quinone reductase 1; a side-chain rotational difference between quinone reductase 1 and quinone reductase 2 of a single residue, phenylalanine 106, determines the specificity of enzymatic activities. These results infer functional differences between two homologous enzymes and indicate that quinone reductase 2 could play important roles in the regulation of catecholamine oxidation processes that may be involved in the etiology of Parkinson disease.

  7. Estrogen Receptor Agonists and Antagonists in the Yeast Estrogen Bioassay.

    PubMed

    Wang, Si; Bovee, Toine F H

    2016-01-01

    Cell-based bioassays can be used to predict the eventual biological activity of a substance on a living organism. In vitro reporter gene bioassays are based on recombinant vertebrate cell lines or yeast strains and especially the latter are easy-to-handle, cheap, and fast. Moreover, yeast cells do not express estrogen, androgen, progesterone or glucocorticoid receptors, and are thus powerful tools in the development of specific reporter gene systems that are devoid of crosstalk from other hormone pathways. This chapter describes our experience with an in-house developed RIKILT yeast estrogen bioassay for testing estrogen receptor agonists and antagonists, focusing on the applicability of the latter. PMID:26585147

  8. PURIFICATION AND RECOVERY OF BULKY HYDROPHOBIC DNA ADDUCTS

    EPA Science Inventory

    For many years 32P postlabeling has detected DNA adducts at very low levels and yet has not been able to identify unknown adducts. Mass spectrometry offers substantially improved identification powers, albeit at some loss in detection limits. With this ultimate utilization of ma...

  9. The antimicrobial activities of the cinnamaldehyde adducts with amino acids.

    PubMed

    Wei, Qing-Yi; Xiong, Jia-Jun; Jiang, Hong; Zhang, Chao; Wen Ye

    2011-11-01

    Cinnamaldehyde is a well-established natural antimicrobial compound. It is probable for cinnamaldehyde to react with amino acid forming Schiff base adduct in real food system. In this paper, 9 such kind of adducts were prepared by the direct reaction of amino acids with cinnamaldehyde at room temperature. Their antimicrobial activities against Bacillus subtilis, Escherichia coli and Saccharomyces cerevisiae were evaluated with benzoic acid as a reference. The adducts showed a dose-dependent activities against the three microbial strains. Both cinnamaldehyde and their adducts were more active against B. subtilis than on E. coli, and their antimicrobial activities were higher at lower pH. Both cinnamaldehyde and its adducts were more active than benzoic acid at the same conditions. The adduct compound A was non-toxic by primary oral acute toxicity study in mice. However, in situ effect of the adduct compound A against E. coli was a little lower than cinnamaldehyde in fish meat. This paper for the first time showed that the cinnamaldehyde adducts with amino acids had similar strong antimicrobial activities as cinnamaldehyde, which may provide alternatives to cinnamaldehyde in food to avoid the strong unacceptable odor of cinnamaldehyde. PMID:21856030

  10. Fluorescence of Phytochrome Adducts with Synthetic Locked Chromophores*

    PubMed Central

    Zienicke, Benjamin; Chen, Li-Yi; Khawn, Htoi; Hammam, Mostafa A. S.; Kinoshita, Hideki; Reichert, Johannes; Ulrich, Anne S.; Inomata, Katsuhiko; Lamparter, Tilman

    2011-01-01

    We performed steady state fluorescence measurements with phytochromes Agp1 and Agp2 of Agrobacterium tumefaciens and three mutants in which photoconversion is inhibited. These proteins were assembled with the natural chromophore biliverdin (BV), with phycoerythrobilin (PEB), which lacks a double bond in the ring C-D-connecting methine bridge, and with synthetic bilin derivatives in which the ring C-D-connecting methine bridge is locked. All PEB and locked chromophore adducts are photoinactive. According to fluorescence quantum yields, the adducts may be divided into four different groups: wild type BV adducts exhibiting a weak fluorescence, mutant BV adducts with about 10-fold enhanced fluorescence, adducts with locked chromophores in which the fluorescence quantum yields are around 0.02, and PEB adducts with a high quantum yield of around 0.5. Thus, the strong fluorescence of the PEB adducts is not reached by the locked chromophore adducts, although the photoconversion energy dissipation pathway is blocked. We therefore suggest that ring D of the bilin chromophore, which contributes to the extended π-electron system of the locked chromophores, provides an energy dissipation pathway that is independent on photoconversion. PMID:21071442

  11. Role of pyridine in Wyodak-pyridine adducts

    SciTech Connect

    David L. Wertz; Amanda Winters; Tara Craft; Jami Holloway

    2006-02-01

    When pyridine (PYR) is added to powdered Wyodak subbituminous coal (WYO), the sample is converted to a paste, and the molecular-level adduct which is formed is stable for months. After the excess pyridine has evaporated from the WYO-PYR sample, the stoichiometry of the adduct is ca. two pyridine molecules per bilayer of WYO polycyclic units; this adduct exists even after mild vacuum treatment of the sample. The pyridine molecules in this adduct appear to be located between the bilayer lamellae and to be H-bonded to either H-O or H-N moieties attached to the poly-cyclic aromatic units of WYO. An H-bonded N- - -H-X distance of 2.6 {angstrom} has been calculated from a structural model of the WYO-PYR adduct. 37 refs., 12 figs., 4 tabs.

  12. General method for quantifying base adducts in specific mammalian genes.

    PubMed Central

    Thomas, D C; Morton, A G; Bohr, V A; Sancar, A

    1988-01-01

    A general method has been developed to measure the formation and removal of DNA adducts in defined sequences of mammalian genomes. Adducted genomic DNA is digested with an appropriate restriction enzyme, treated with Escherichia coli UvrABC excision nuclease (ABC excinuclease), subjected to alkaline gel electrophoresis, and probed for specific sequences by Southern hybridization. The ABC excinuclease incises DNA containing bulky adducts and thus reduces the intensity of the full-length fragments in Southern hybridization in proportion to the number of adducts present in the probed sequence. This method is similar to that developed by Bohr et al. [Bohr, V. A., Smith, C. A., Okumoto, D. S. & Hanawalt, P. C. (1985) Cell 40, 359-369] for quantifying pyrimidine dimers by using T4 endonuclease V. Because of the wide substrate range of ABC exinuclease, however, our method can be used to quantify a large variety of DNA adducts in specific genomic sequences. Images PMID:2836856

  13. Estrogen receptor signaling during vertebrate development

    PubMed Central

    Bondesson, Maria; Hao, Ruixin; Lin, Chin-Yo; Williams, Cecilia; Gustafsson, Jan-Åke

    2014-01-01

    Estrogen receptors are expressed and their cognate ligands produced in all vertebrates, indicative of important and conserved functions. Through evolution estrogen has been involved in controlling reproduction, affecting both the development of reproductive organs and reproductive behavior. This review broadly describes the synthesis of estrogens and the expression patterns of aromatase and the estrogen receptors, in relation to estrogen functions in the developing fetus and child. We focus on the role of estrogens for development of reproductive tissues, as well as non-reproductive effects on the developing brain. We collate data from human, rodent, bird and fish studies and highlight common and species-specific effects of estrogen signaling on fetal development. Morphological malformations originating from perturbed estrogen signaling in estrogen receptor and aromatase knockout mice are discussed, as well as the clinical manifestations of rare estrogen receptor alpha and aromatase gene mutations in humans. PMID:24954179

  14. Effect of an allophanic soil on humification reactions between catechol and glycine: Spectroscopic investigations of reaction products

    NASA Astrophysics Data System (ADS)

    Fukushima, Masami; Miura, Akitaka; Sasaki, Masahide; Izumo, Kenji

    2009-01-01

    Adduction of amino acids to phenols is a possible humification reaction pathway [F.J. Stevenson, Humus Chemistry: Genesis, Composition, Reaction, second ed., Wiley, New York, 1994, pp. 188-211; M.C. Wang, P.M. Huang, Sci. Total Environ. 62 (1987) 435; M.C. Wang, P.M. Huang, Soil Sci. Soc. Am. J. 55 (1991) 1156; M.C. Wang, P.M. Huang, Geoderma 112 (2003) 31; M.C. Wang, P.M. Huang, Geoderma 124 (2005) 415]. To elucidate the reaction kinetics and products of abiotic humification, the effects of an allophanic soil on the adduction of amino acids to phenols were investigated using catechol (CT) and glycine (Gly) as a model phenol and amino acid, respectively. An aqueous solution containing CT and Gly (pH 7.0) in the presence of allophanic soil was incubated for 2 weeks, and the kinetics of the humification reactions were monitored by analysis of absorptivity at 600 nm ( E600). A mixture of CT and Gly in the absence of allophanic soil was used as a control. The E600 value increased markedly in the presence of allophanic soil. In addition, unreacted CT was detected in the control reaction mixture, but not in the allophane-containing reaction mixture. Under the sterilized conditions, absorbance at 600 nm for the control reaction mixture was significantly smaller than that for the allophanic soil-containing reaction mixture, which indicates there was no microbial participation during incubation. These results indicate that the allophanic soil effectively facilitated humification reactions between CT and Gly. The reaction mixtures were acidified and humic-like acid (HLA) was isolated as a precipitate. The elemental composition, acidic functional group contents, molecular weight, FT-IR, solid-state CP-MAS 13C NMR, and 1H NMR spectra of the purified HLAs were analyzed. The results of these analyses indicate that the nitrogen atom of Gly binds to the aromatic carbon of CT in the HLA products.

  15. BIOLOGICAL ADHESIVES. Adaptive synergy between catechol and lysine promotes wet adhesion by surface salt displacement.

    PubMed

    Maier, Greg P; Rapp, Michael V; Waite, J Herbert; Israelachvili, Jacob N; Butler, Alison

    2015-08-01

    In physiological fluids and seawater, adhesion of synthetic polymers to solid surfaces is severely limited by high salt, pH, and hydration, yet these conditions have not deterred the evolution of effective adhesion by mussels. Mussel foot proteins provide insights about adhesive adaptations: Notably, the abundance and proximity of catecholic Dopa (3,4-dihydroxyphenylalanine) and lysine residues hint at a synergistic interplay in adhesion. Certain siderophores—bacterial iron chelators—consist of paired catechol and lysine functionalities, thereby providing a convenient experimental platform to explore molecular synergies in bioadhesion. These siderophores and synthetic analogs exhibit robust adhesion energies (E(ad) ≥-15 millijoules per square meter) to mica in saline pH 3.5 to 7.5 and resist oxidation. The adjacent catechol-lysine placement provides a "one-two punch," whereby lysine evicts hydrated cations from the mineral surface, allowing catechol binding to underlying oxides. PMID:26250681

  16. Specificity of catechol ortho-cleavage during para-toluate degradation by Rhodococcus opacus 1cp.

    PubMed

    Suvorova, M M; Solianikova, I P; Golovleva, L A

    2006-12-01

    Degradation of para-toluate by Rhodococcus opacus 1cp was investigated. Activities of the key enzymes of this process, catechol 1,2-dioxygenase and muconate cycloisomerase, are detected in this microorganism. Growth on p-toluate was accompanied by induction of two catechol 1,2-dioxygenases. The substrate specificity and physicochemical properties of one enzyme are identical to those of chlorocatechol 1,2-dioxygenase; induction of the latter enzyme was observed during R. opacus 1cp growth on 4-chlorophenol. The other enzyme isolated from the biomass grown on p-toluate exhibited lower rate of chlorinated substrate cleavage compared to the catechol substrate. However, this enzyme is not identical to the catechol 1,2-dioxygenase cloned in this strain within the benzoate catabolism operon. This supports the hypothesis on the existence of multiple forms of dioxygenases as adaptive reactions of microorganisms in response to environmental stress.

  17. H-point curve isolation method for determination of catechol in complex unknown mixtures

    NASA Astrophysics Data System (ADS)

    Hasani, Masoumeh; Mohammadi, Masoumeh; Shariati-Rad, Masoud; Abdollahi, Hamid

    2012-10-01

    In this work, the combination of H-point curve isolation method (HPCIM) and H-point standard additions method (HPSAM) was used for determination of catechol in the presence of phenolic interferents. Spectrophotometric multivariate calibration data constructed by successive standard additions of an analyte in an unknown matrix was used by the method. A cumulative spectrum for interferents in sample was extracted by HPCIM and then HPSAM is used for determination of the catechol concentration by obtained cumulative interferents spectrum. The method was tested with simulated data set. The spectrum obtained from applying HPCIM to the simulated data well agrees with the cumulative spectra of the interferents. The method was applied to the determination of catechol in the presence of highly overlapping interferents in synthetic ternary mixtures using spectrophotometric data. Moreover, the proposed method was successfully used for determination of catechol in real complicated matrices of tea and urine samples. Percent recoveries were between 95.4 and 113.6.

  18. BIOLOGICAL ADHESIVES. Adaptive synergy between catechol and lysine promotes wet adhesion by surface salt displacement.

    PubMed

    Maier, Greg P; Rapp, Michael V; Waite, J Herbert; Israelachvili, Jacob N; Butler, Alison

    2015-08-01

    In physiological fluids and seawater, adhesion of synthetic polymers to solid surfaces is severely limited by high salt, pH, and hydration, yet these conditions have not deterred the evolution of effective adhesion by mussels. Mussel foot proteins provide insights about adhesive adaptations: Notably, the abundance and proximity of catecholic Dopa (3,4-dihydroxyphenylalanine) and lysine residues hint at a synergistic interplay in adhesion. Certain siderophores—bacterial iron chelators—consist of paired catechol and lysine functionalities, thereby providing a convenient experimental platform to explore molecular synergies in bioadhesion. These siderophores and synthetic analogs exhibit robust adhesion energies (E(ad) ≥-15 millijoules per square meter) to mica in saline pH 3.5 to 7.5 and resist oxidation. The adjacent catechol-lysine placement provides a "one-two punch," whereby lysine evicts hydrated cations from the mineral surface, allowing catechol binding to underlying oxides.

  19. Protein-responsive assemblies from catechol-metal ion supramolecular coordination.

    PubMed

    Yuan, C; Chen, J; Yu, S; Chang, Y; Mao, J; Xu, Y; Luo, W; Zeng, B; Dai, L

    2015-03-21

    Supramolecular self-assembly driven by catechol-metal ion coordination has gained great success in the fabrication of functional materials including adhesives, capsules, coatings and hydrogels. However, this route has encountered a great challenge in the construction of nanoarchitectures in the absence of removable templates, because of the uncontrollable crosslinking of catechol-metal ion coordination. Herein, we show that a supramolecular approach, combining both catechol-metal ion coordination and polymer self-assembly together, can organize polymers into hybrid nanoassemblies ranging from solid particles, homogeneous vesicles to Janus vesicles. Without the introduction of a specific binding ligand or complicated molecular design, these assemblies can totally disassemble in response to proteins. UV/vis absorption, fluorescence quenching and recovery investigations have confirmed that proteins can seize metal ions from the hybrid nanoassemblies, thus causing the degradation of catechol-metal ion coordination networks.

  20. Catechol oxidase activity of di-Cu2+-substituted aminopeptidase from Streptomyces griseus.

    PubMed

    da Silva, Giordano F Z; Ming, Li-June

    2005-11-30

    Streptomyces griseus aminopeptidase exhibits activities toward the hydrolyses of peptides and bis(p-nitrophenyl)phosphate (40 billion fold) and catechol oxidation reported herein with catalytic efficiency (kcat/Km) only about 10 times smaller than that of gypsywort catechol oxidase. The multifunctionality of this enzyme suggests that it is a unique system for further exploration of protein structure and function and a template for design of enzymes of diverse activities. PMID:16305209

  1. Heterogeneous reactions of surface-adsorbed catechol with nitrogen dioxide: substrate effects for tropospheric aerosol surrogates.

    PubMed

    Woodill, Laurie A; Hinrichs, Ryan Z

    2010-09-28

    Surface-adsorbed organics can alter the chemistry of tropospheric aerosols thereby impacting photochemical cycles and altering aerosol properties. The nature of the surface can also influence the chemistry of the surface-adsorbed organic. We employed diffuse reflectance infrared spectroscopy (DRIFTS) to monitor the adsorption of gaseous catechol on several tropospheric aerosol surrogates and to investigate the subsequent reactivity of adsorbed catechol with nitrogen dioxide. The dark heterogeneous reaction of NO(2) with NaCl-adsorbed catechol produced 4-nitrocatechol, 1,2-benzoquinone, and the ring-cleaved product muconic acid, with product yields of 88%, 8%, and 4% at relative humidity (RH) < 2%, respectively. The reaction was first-order with respect to both catechol and NO(2). The reactive uptake coefficient for NO(2) + NaCl-adsorbed catechol increased from 3 x 10(-6) at <2% RH to 7 x 10(-6) at 30% RH. These reactions were more than two orders of magnitude more reactive than NaCl without adsorbed catechol. The 4-nitrocatechol product yield was enhanced on NaF, while NaBr-adsorbed catechol produced considerably more 1,2-benzoquinone and muconic acid. This substrate effect is discussed in terms of each substrate's ability to polarize the phenol group and hinder hydrogen atom abstraction from intermediate o-semiquinone radicals. These dark heterogeneous reactions may alter the UV-visible absorbing properties of tropospheric aerosols and may also contribute as a dark source of NO(2)(-)/HONO. These results contrast prior observations which found pure catechol thin films unreactive with NO(2), highlighting the need to specifically consider substrate and matrix effects in laboratory systems.

  2. The knee adduction moment during gait is associated with the adduction angle measured during computer-assisted total knee arthroplasty.

    PubMed

    Roda, Richard D; Wilson, Janie L Astephen; Wilson, David A J; Richardson, Glen; Dunbar, Michael J

    2012-06-01

    Computer-assisted surgery can be used to measure 3-dimensional knee function during arthroplasty surgery; however, it is unknown if the movement of the knee measured during surgery is related to the in vitro, dynamic state of the knee joint, specifically the knee adduction moment during gait, which has been related to implant migration. The purpose of this study was to determine if the preoperative adduction moment is correlated with the knee abduction/adduction angle measured intraoperatively. A statistically significant correlation was found between the mean (r(2) = 0.59; P = .001) and peak (r(2) = 0.53; P = .003) preoperative knee adduction moment and the mean abduction/adduction angle measured intraoperatively. The association found in this study suggests the potential for incorporating functional information that relates to surgical outcome into surgical decision making using computer-assisted surgery.

  3. The Formation and Biological Significance of N7-Guanine Adducts

    PubMed Central

    Boysen, Gunnar; Pachkowski, Brian F.; Nakamura, Jun; Swenberg, James A

    2009-01-01

    DNA alkylation or adduct formation occurs at nucleophilic sites in DNA, mainly the N7-position of guanine. Ever since identification of the first N7-guanine adduct, several hundred studies on DNA adducts have been reported. Major issues addressed include the relationships between N7-guanine adducts and exposure, mutagenesis, and other biological endpoints. It became quickly apparent that N7-guanine adducts are frequently formed, but may have minimal biological relevance, since they are chemically unstable and do not participate in Watson Crick base pairing. However, N7-guanine adducts have been shown to be excellent biomarkers for internal exposure to direct acting and metabolically activated carcinogens. Questions arise, however, regarding the biological significance for N7-guanine adducts that are readily formed, do not persist, and are not likely to be mutagenic. Thus, we set out to review the current literature to evaluate their formation and the mechanistic evidence for the involvement of N7-guanine adducts in mutagenesis or other biological processes. It was concluded that there is insufficient evidence that N7-guanine adducts can be used beyond confirmation of exposure to the target tissue and demonstration of the molecular dose. There is little to no evidence that N7-guanine adducts or their depurination product, apurinic sites, are the cause of mutations in cells and tissues, since increases in AP sites have not been shown unless toxicity is extant. However, more research is needed to define the extent of chemical depurination versus removal by DNA repair proteins. Interestingly, N7-guanine adducts are clearly present as endogenous background adducts and the endogenous background amounts appear to increase with age. Furthermore, the N7-guanine adducts have been shown to convert to ring opened lesions (FAPy), which are much more persistent and have higher mutagenic potency. Studies in humans are limited in sample size and differences between controls and

  4. Characterization of catechol derivative removal by lignin peroxidase in aqueous mixture.

    PubMed

    Cohen, Shaul; Belinky, Paula A; Hadar, Yitzhak; Dosoretz, Carlos G

    2009-04-01

    The use of lignin peroxidase (LIP) as an alternative method for the removal of four catechols (1,2-dihydroxybenzene): catechol (CAT), 4-chlorocatechol (4-CC), 4,5-dichlorocatechol (4,5-DCC) and 4-methylcatechol (4-MC) typical pollutants in wastewater derived from oil and paper industries, was evaluated. The removal of 2mM catecholic substrates by 1 microM LIP after 1h was in the following order: 4,5-DCC (95%)>4-CC(90%)>CAT(55%)>4-MC(43%). Except for 4-MC, all reactions were accompanied by the formation of insoluble products, leading to LIP precipitation. LIP was exposed to soluble or insoluble product-dependent inactivation, depending on the substrates tested, immediately at the start of the reactions. Despite immediate enzyme inactivation, removal of catecholic substrates continued, resulting in oligomeric product formation. Major oxidation products analyzed were compatible with dimeric, trimeric and tetrameric structures. Ether linkages and a benzoquinone structure were detected in two purified oligochlorocatechols. Catechol derivatives removal initiated by LIP, seems to be different for each catecholic substrate in terms of substrate consumption and transformation, and of enzyme activity.

  5. Biocatalytic Reductions of Baylis - Hillman Adducts

    SciTech Connect

    A Walton; W Conerly; Y Pompeu; B Sullivan; J Stewart

    2011-12-31

    Baylis-Hillman adducts are highly useful synthetic intermediates; to enhance their value further, we sought enantiocomplementary alkene reductases to introduce chirality. Two solutions emerged: (1) a wild-type protein from Pichia stipitis (OYE 2.6), whose performance significantly outstrips that of the standard enzyme (Saccharomyces pastorianus OYE1), and (2) a series of OYE1 mutants at position 116 (Trp in the wild-type enzyme). To understand how mutations could lead to inverted enantioselectivity, we solved the X-ray crystal structure of the Trp116Ile OYE1 variant complexed with a cyclopentenone substrate. This revealed key protein-ligand interactions that control the orientation of substrate binding above the FMN cofactor.

  6. DNA adduct formation by alachlor metabolites

    SciTech Connect

    Brown, M.A.; Kimmel, E.C.; Casida, J.E.

    1988-01-01

    The extent of DNA adduct formation by alachlor (ArN(CH/sub 2/OCH/sub 3/)C(O)CH/sub 2/Cl wherein Ar is 2,6-diethylphenyl) and its metabolites is used as a guide to deduce the causal agent(s) in the carcinogenicity of this major herbicide. (/sup 14/C-phenyl)Alachlor is compared to its two metabolic cleavage products, (/sup 14/C-phenyl) 2-chloro-N-(2,6-diethylphenyl)acetamide (CDEPA) (ArNHC(O)CH/sub 2/Cl) and (/sup 14/C-phenyl)2,6-diethylaniline (DEA) (ArNH/sub 2/), and to (/sup 14/C-methoxy)alachlor in various in vitro and in vivo systems. Horseradish peroxidase and hydrogen peroxide activate DEA, but not CEDPA or alachlor, for formation of adducts with calf thymus DNA, which probably involves 2,6-diethylnitrosobenzene (ArNO) as an intermediate. Mouse liver microsomes and NADPH are both required to enhance the binding from each labeled preparation to calf thymus DNA; 4-fold higher labeling is observed from (/sup 14/C-methoxy)- than from (/sup 14/C-phenyl)alachlor. This 4-fold preferential DNA labeling from the /sup 14/C-methoxy compound is likewise found in the liver of mice treated intraperitoneally. Mouse liver protein and hemoglobin are also labeled, in vivo, with (/sup 14/C-phenyl)alachlor, -CDEPA and -DEA, and, as with the DNA, the labeling of these proteins is 1.5- to 2-fold higher with (/sup 14/C-methoxy)alachlor.

  7. Prolonged Acetaminophen-Protein Adduct Elimination During Renal Failure, Lack of Adduct Removal by Hemodiafiltration, and Urinary Adduct Concentrations After Acetaminophen Overdose.

    PubMed

    Curry, Steven C; Padilla-Jones, Angela; O'Connor, Ayrn D; Ruha, Anne-Michelle; Bikin, Dale S; Wilkins, Diana G; Rollins, Douglas E; Slawson, Matthew H; Gerkin, Richard D

    2015-06-01

    Elevated concentrations of serum acetaminophen-protein adducts, measured as protein-derived acetaminophen-cysteine (APAP-CYS), have been used to support a diagnosis of APAP-induced liver injury when histories and APAP levels are unhelpful. Adducts have been reported to undergo first-order elimination, with a terminal half-life of about 1.6 days. We wondered whether renal failure would affect APAP-CYS elimination half-life and whether continuous venovenous hemodiafiltration (CVVHDF), commonly used in liver failure patients, would remove adducts to lower their serum concentrations. Terminal elimination half-lives of serum APAP-CYS were compared between subjects with and without renal failure in a prospective cohort study of 168 adults who had ingested excessive doses of APAP. APAP-CYS concentrations were measured in plasma ultrafiltrate during CVVHDF at times of elevated serum adduct concentrations. Paired samples of urine and serum APAP-CYS concentrations were examined to help understand the potential importance of urinary elimination of serum adducts. APAP-CYS elimination half-life was longer in 15 renal failure subjects than in 28 subjects with normal renal function (41.3 ± 2.2 h versus 26.8 ± 1.1 h [mean ± SEM], respectively, p < 0.001). CVVHDF failed to remove detectable amounts of APAP-CYS in any of the nine subjects studied. Sixty-eight percent of 557 urine samples from 168 subjects contained no detectable APAP-CYS, despite levels in serum up to 16.99 μM. Terminal elimination half-life of serum APAP-CYS was prolonged in patients with renal failure for reasons unrelated to renal urinary adduct elimination, and consideration of prolonged elimination needs to be considered if attempting back-extrapolation of adduct concentrations. CVVHDF did not remove detectable APAP-CYS, suggesting approximate APAP-protein adduct molecular weights ≥ 50,000 Da. The presence of urinary APAP-CYS in the minority of instances was most compatible with renal

  8. Quantitation of DNA adducts by stable isotope dilution mass spectrometry

    PubMed Central

    Tretyakova, Natalia; Goggin, Melissa; Janis, Gregory

    2012-01-01

    Exposure to endogenous and exogenous chemicals can lead to the formation of structurally modified DNA bases (DNA adducts). If not repaired, these nucleobase lesions can cause polymerase errors during DNA replication, leading to heritable mutations potentially contributing to the development of cancer. Due to their critical role in cancer initiation, DNA adducts represent mechanism-based biomarkers of carcinogen exposure, and their quantitation is particularly useful for cancer risk assessment. DNA adducts are also valuable in mechanistic studies linking tumorigenic effects of environmental and industrial carcinogens to specific electrophilic species generated from their metabolism. While multiple experimental methodologies have been developed for DNA adduct analysis in biological samples – including immunoassay, HPLC, and 32P-postlabeling – isotope dilution high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) generally has superior selectivity, sensitivity, accuracy, and reproducibility. As typical DNA adducts concentrations in biological samples are between 0.01 – 10 adducts per 108 normal nucleotides, ultrasensitive HPLC-ESI-MS/MS methodologies are required for their analysis. Recent developments in analytical separations and biological mass spectrometry – especially nanoflow HPLC, nanospray ionization MS, chip-MS, and high resolution MS – have pushed the limits of analytical HPLC-ESI-MS/MS methodologies for DNA adducts, allowing researchers to accurately measure their concentrations in biological samples from patients treated with DNA alkylating drugs and in populations exposed to carcinogens from urban air, drinking water, cooked food, alcohol, and cigarette smoke. PMID:22827593

  9. Heterogeneous Reactions of Surface-Adsorbed Catechol: A Comparison of Tropospheric Aerosol Surrogates

    NASA Astrophysics Data System (ADS)

    Hinrichs, R. Z.; Woodill, L. A.

    2009-12-01

    Surface-adsorbed organics can alter the chemistry of tropospheric solid-air interfaces, such as aerosol and ground level surfaces, thereby impacting photochemical cycles and altering aerosol properties. The nature of the surface can also influence the chemistry of the surface-adsorbed organic. We employed diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to monitor the adsorption of gaseous catechol on several tropospheric aerosol surrogates and to investigate the subsequent reactivity of adsorbed-catechol with nitrogen dioxide and, in separate preliminary experiments, ozone. Graphite, kaolinite, and sodium halide (NaF, NaCl, NaBr) powders served as carbonaceous, mineral and sea salt aerosol surrogates, respectively. Broad OH stretching bands for adsorbed catechol shifted to lower wavenumber with peak frequencies following the trend NaBr > NaCl > NaF ≈ kaolinite, consistent with the increasing basicity of the halide anions and basic Brønsted sites on kaolinite. The dark heterogeneous reaction of NO2 with NaCl-adsorbed catechol at relative humidity (RH) <2% promoted nitration forming 4-nitrocatechol and oxidation forming 1,2-benzoquinone and the ring cleavage product muconic acid, with product yields of 88%, 8%, and 4%, respectively. 4-Nitrocatechol was the dominant product for catechol adsorbed on NaF and kaolinite, while NaBr-adsorbed catechol produced less 4-nitrocatechol and more 1,2-benzoquinone and muconic acid. For all three sodium halides, the reactions of NO2 with adsorbed catechol were orders of magnitude faster than between NO2 and each NaX substrate. 4-Nitrocatechol rates and product yields were consistent with the relative ability of each substrate to enhance the deprotonated nature of adsorbed-catechol. Increasing the relative humidity caused the rate of each product channel to decrease and also altered the product branching ratios. Most notably, 1,2-benzoquinone formation decreased significantly even at 13% RH. The dramatic

  10. Structural and spectroscopic studies of a model for catechol oxidase.

    PubMed

    Smith, Sarah J; Noble, Christopher J; Palmer, Randahl C; Hanson, Graeme R; Schenk, Gerhard; Gahan, Lawrence R; Riley, Mark J

    2008-05-01

    A binuclear copper complex, [Cu2(BPMP) (OAc)2][ClO4] x H2O, has been prepared using the binucleating ligand 2,6-bis[bis(pyridin-2-ylmethylamino)methyl]-4-methylphenol (H-BPMP). The X-ray crystal structure reveals the copper centers to have a five-coordinate square pyramidal geometry, with the acetate ligands bound terminally. The bridging phenolate occupies the apical position of the square-based pyramids and magnetic susceptibility, electron paramagnetic resonance (EPR) and variable-temperature variable-field magnetic circular dichroism (MCD) measurements indicate that the two centers are very weakly antiferromagnetically coupled (J = -0.6 cm(-1)). Simulation of the dipole-dipole-coupled EPR spectrum showed that in solution the Cu-O-Cu angle was increased from 126 degrees to 160 degrees and that the internuclear distance was larger than that observed crystallographically. The high-resolution spectroscopic information obtained has been correlated with a detailed ligand-field analysis to gain insight into the electronic structure of the complex. Symmetry arguments have been used to demonstrate that the sign of the MCD is characteristic of the tetragonally elongated environment. The complex also displays catecholase activity (k(cat) = 15 +/- 1.5 min(-1), K(M) = 6.4 +/- 1.8 mM), which is compared with other dicopper catechol oxidase models. PMID:18188615

  11. DNA and protein adducts as markers of genotoxicity.

    PubMed

    Farmer, Peter B

    2004-04-01

    Determination of the interaction products (adducts) of a carcinogen with DNA or protein indicates the amount of genotoxic material that has reached the tissue under study and provides a valuable biomarker of exposure for molecular epidemiological studies. DNA adducts may also give further information with regard to the mutagenic significance of the exposure. The sensitivity and applicability of the analytical methods for the detection and quantification of carcinogen adducts has greatly increased in recent years, and DNA damage levels as low as one adduct per 10(8) nucleotides can now routinely be measured. The discovery of many types of endogenously-produced damage of DNA and protein has demonstrated previously unsuspected sources of genotoxicity, the biological consequences of which are so far not known.

  12. Paclitaxel Enhances Carboplatin-DNA Adduct Formation and Cytotoxicity

    DOE PAGES

    Jiang, Shuai; Pan, Amy W.; Lin, Tzu-yin; Zhang, Hongyong; Malfatti, Michael; Turteltaub, Kenneth; Henderson, Paul T.; Pan, Chong-xian

    2015-11-06

    This rapid report focuses on the pharmacodynamic mechanism of the carboplatin/paclitaxel combination and correlates it with its cytotoxicity. Consistent with the synergistic to additive antitumor activity (the combination index ranging from 0.53 to 0.94), cells exposed to this combination had significantly increased carboplatin-DNA adduct formation when compared to that of carboplatin alone (450 ± 30 versus 320 ± 120 adducts per 108 nucleotides at 2 h, p = 0.004). Removal of paclitaxel increased the repair of carboplatin-DNA adducts: 39.4 versus 33.1 adducts per 108 nucleotides per hour in carboplatin alone (p = 0.021). In conclusion, this rapid report provides themore » first pharmacodynamics data to support the use of carboplatin/paclitaxel combination in the clinic.« less

  13. Paclitaxel Enhances Carboplatin-DNA Adduct Formation and Cytotoxicity

    SciTech Connect

    Jiang, Shuai; Pan, Amy W.; Lin, Tzu-yin; Zhang, Hongyong; Malfatti, Michael; Turteltaub, Kenneth; Henderson, Paul T.; Pan, Chong-xian

    2015-11-06

    This rapid report focuses on the pharmacodynamic mechanism of the carboplatin/paclitaxel combination and correlates it with its cytotoxicity. Consistent with the synergistic to additive antitumor activity (the combination index ranging from 0.53 to 0.94), cells exposed to this combination had significantly increased carboplatin-DNA adduct formation when compared to that of carboplatin alone (450 ± 30 versus 320 ± 120 adducts per 108 nucleotides at 2 h, p = 0.004). Removal of paclitaxel increased the repair of carboplatin-DNA adducts: 39.4 versus 33.1 adducts per 108 nucleotides per hour in carboplatin alone (p = 0.021). In conclusion, this rapid report provides the first pharmacodynamics data to support the use of carboplatin/paclitaxel combination in the clinic.

  14. Paclitaxel Enhances Carboplatin-DNA Adduct Formation and Cytotoxicity.

    PubMed

    Jiang, Shuai; Pan, Amy W; Lin, Tzu-yin; Zhang, Hongyong; Malfatti, Michael; Turteltaub, Kenneth; Henderson, Paul T; Pan, Chong-xian

    2015-12-21

    This rapid report focuses on the pharmacodynamic mechanism of the carboplatin/paclitaxel combination and correlates it with its cytotoxicity. Consistent with the synergistic to additive antitumor activity (the combination index ranging from 0.53 to 0.94), cells exposed to this combination had significantly increased carboplatin-DNA adduct formation when compared to that of carboplatin alone (450 ± 30 versus 320 ± 120 adducts per 10(8) nucleotides at 2 h, p = 0.004). Removal of paclitaxel increased the repair of carboplatin-DNA adducts: 39.4 versus 33.1 adducts per 10(8) nucleotides per hour in carboplatin alone (p = 0.021). This rapid report provides the first pharmacodynamics data to support the use of carboplatin/paclitaxel combination in the clinic.

  15. Radicals from the gas-phase pyrolysis of catechol: 1. o-Semiquinone and ipso-catechol radicals.

    PubMed

    Khachatryan, Lavrent; Adounkpe, Julien; Asatryan, Rubik; Dellinger, Barry

    2010-02-18

    The formation of environmentally persistent free radicals (EPFRs) from the gas-phase pyrolysis of catechol (CT) was studied over a temperature range of 400-750 degrees C using the technique of low-temperature matrix isolation electron paramagnetic resonance (LTMI-EPR) spectroscopy. A split singlet EPR spectrum with a g value of 2.0052 was observed. To aid in the interpretation of this spectrum, a detailed analysis of the potential energy surface of CT decomposition pathways was performed employing CBS-QB3 multilevel and DFT individual methods. The energetically favored channels were the formation of ipso- and alpha-CT isomers of CT as well as o-semiquinone (o-SQ) radicals from ipso- and alpha-CT. ipso-CT as well as open ipso-CT radicals were apparently unstable intermediates that could not be accumulated in sufficiently high concentrations to be detected by EPR. The calculated EPR spectrum of o-SQ radical is consistent with the formation of an oxygen-centered radical with a high g value observed experimentally. The hyperfine splitting of the observed spectrum can be attributed to the formation of hydrogen bonds in radical dimers. The lack of experimental observation of o-benzoquinone, an anticipated pyrolysis product, has been explained based on theoretical calculations.

  16. Estrogens and development of pulmonary hypertension - Interaction of estradiol metabolism and pulmonary vascular disease

    PubMed Central

    Tofovic, Stevan P.

    2010-01-01

    Severe pulmonary arterial hypertension (PAH) is characterized by clustered proliferation of endothelial cells in the lumina of small size pulmonary arteries resulting in concentric obliteration of the lumina and formation of complex vascular structures known as plexiform lesions. This debilitating disease occurs more frequently in women, yet both animal studies in classical models of PAH and limited clinical data suggest protective effects of estrogens: the estrogen paradox in pulmonary hypertension. Little is known about the role of estrogens in PAH, but one line of evidence strongly suggests that the vascular protective effects of 17β-estradiol (estradiol; E2) are mediated largely by its downstream metabolites. Estradiol is metabolized to 2-hydroxyestradiol (2HE) by CYP1A1/CYP1B1, and 2HE is converted to 2-methoxyestradiol (2ME) by catechol-O-methyl transferase. 2ME is extensively metabolized to 2-methoxyestrone, a metabolite that lacks biologic activity but which may be converted back to 2ME. 2ME has no estrogenic activity and its effects are mediated by estrogen receptors-independent mechanism(s). Notably, in systemic and pulmonary vascular endothelial cells, smooth muscle cells, and fibroblasts 2ME exerts stronger anti-mitotic effects than E2 itself. E2 and 2ME, despite having similar effects on other cardiovascular cells, have opposing effects on endothelial cells; that is, in endothelial cells, E2 is pro-mitogenic, pro-angiogenic and anti- apoptotic, whereas 2ME is antimitogenic, anti-angiogenic and pro-apoptotic. This may have significant ramifications in severe PAH that involves uncontrolled proliferation of monoclonal, apoptosis resistant endothelial cells. Based on its cellular effects, 2ME should be expected to attenuate the progression of disease and provide protection in severe PAH. In contrast, E2, due to its mitogenic, angiogenic, and anti-apoptotic effects (otherwise desirable in normal, quiescent endothelial cells), may even adversely affect

  17. Selective syntheses of novel polyether fullerene multiple adducts.

    PubMed

    Zhou, Zhiguo; Schuster, David I; Wilson, Stephen R

    2003-10-01

    We have applied a modified macrocyclic tether approach to control multiple additions to C60. The technique of 3He NMR was used to confirm the selective formation of specific C60 multiple adducts by the macrocyclic tether approach. An oligoglycol was used as a flexible linker to produce macrocyclic polyether-linked malonates 5, 6, 8, and 9 under solid-liquid PTC (phase-transfer-catalysis) conditions. The formation of a single C60 tris-adduct, 3, from macrocyclic malonate 1 and 3He@C60 was proven by 3He NMR. Similarly, multiple additions to C60 of macrocyclic polyether malonate 5 gave C60 bis-adduct 10 selectively, while the reaction of C60 with macrocyclic malonate 8 gave bis-adducts 11 and 12. A similar process with macrocyclic malonate 6 gave tris-adduct 13 with high selectivity as well. Saponification of these C60 multiple adducts gives the corresponding polyacids that are potentially useful in biological applications. Macrocyclic polyether fullerenes are a new class of ionophores, which could be interesting for molecular recognition and for the development of biosensors.

  18. Relating protein adduction to gene expression changes: a systems approach

    PubMed Central

    Zhang, Bing; Shi, Zhiao; Duncan, Dexter T; Prodduturi, Naresh; Marnett, Lawrence J; Liebler, Daniel C

    2013-01-01

    Modification of proteins by reactive electrophiles such as the 4-hydroxy-2-nonenal (HNE) plays a critical role in oxidant-associated human diseases. However, little is known about protein adduction and the mechanism by which protein damage elicits adaptive effects and toxicity. We developed a systems approach for relating protein adduction to gene expression changes through the integration of protein adduction, gene expression, protein-DNA interaction, and protein-protein interaction data. Using a random walk strategy, we expanded a list of responsive transcription factors inferred from gene expression studies to upstream signaling networks, which in turn allowed overlaying protein adduction data on the network for the prediction of stress sensors and their associated regulatory mechanisms. We demonstrated the general applicability of transcription factor-based signaling network inference using 103 known pathways. Applying our workflow on gene expression and protein adduction data from HNE-treatment not only rediscovered known mechanisms of electrophile stress but also generated novel hypotheses regarding protein damage sensors. Although developed for analyzing protein adduction data, the framework can be easily adapted for phosphoproteomics and other types of protein modification data. PMID:21594272

  19. ³²P-postlabeling analysis of DNA adducts.

    PubMed

    Phillips, David H; Arlt, Volker M

    2014-01-01

    (32)P-Postlabeling analysis is an ultra-sensitive method for the detection of DNA adducts, such as those formed directly by the covalent binding of carcinogens and mutagens to bases in DNA and other DNA lesions resulting from modification of bases by endogenous or exogenous agents (e.g., oxidative damage). The procedure involves four main steps: enzymatic digestion of the DNA sample; enrichment of the adducts; radiolabeling of the adducts by T4 kinase-catalyzed transference of (32)P-orthophosphate from [γ-(32)P]ATP; chromatographic separation of labeled adducts; and detection and quantification by means of their radioactive decay. Using 10 μg of DNA or less, it is capable of detecting adduct levels as low as 1 adduct in 10(9)-10(10) normal nucleotides. It is applicable to a wide range of investigations, including monitoring human exposure to environmental or occupational carcinogens, determining whether a chemical has genotoxic properties, analysis of the genotoxicity of complex mixtures, elucidation of the pathways of activation of carcinogens, and monitoring DNA repair. PMID:24623224

  20. Dietary quercetin exacerbates the development of estrogen-induced breast tumors in female ACI rats

    SciTech Connect

    Singh, Bhupendra; Mense, Sarah M.; Bhat, Nimee K.; Putty, Sandeep; Guthiel, William A.; Remotti, Fabrizio; Bhat, Hari K.

    2010-09-01

    Phytoestrogens are plant compounds that structurally mimic the endogenous estrogen 17{beta}-estradiol (E{sub 2}). Despite intense investigation, the net effect of phytoestrogen exposure on the breast remains unclear. The objective of the current study was to examine the effects of quercetin on E{sub 2}-induced breast cancer in vivo. Female ACI rats were given quercetin (2.5 g/kg food) for 8 months. Animals were monitored weekly for palpable tumors, and at the end of the experiment, rats were euthanized, breast tumor and different tissues excised so that they could be examined for histopathologic changes, estrogen metabolic activity and oxidant stress. Quercetin alone did not induce mammary tumors in female ACI rats. However, in rats implanted with E{sub 2} pellets, co-exposure to quercetin did not protect rats from E{sub 2}-induced breast tumor development with 100% of the animals developing breast tumors within 8 months of treatment. No changes in serum quercetin levels were observed in quercetin and quercetin + E{sub 2}-treated groups at the end of the experiment. Tumor latency was significantly decreased among rats from the quercetin + E{sub 2} group relative to those in the E{sub 2} group. Catechol-O-methyltransferase (COMT) activity was significantly downregulated in quercetin-exposed mammary tissue. Analysis of 8-isoprostane F{sub 2{alpha}} (8-iso-PGF{sub 2{alpha}}) levels as a marker of oxidant stress showed that quercetin did not decrease E{sub 2}-induced oxidant stress. These results indicate that quercetin (2.5 g/kg food) does not confer protection against breast cancer, does not inhibit E{sub 2}-induced oxidant stress and may exacerbate breast carcinogenesis in E{sub 2}-treated ACI rats. Inhibition of COMT activity by quercetin may expose breast cells chronically to E{sub 2} and catechol estrogens. This would permit longer exposure times to the carcinogenic metabolites of E{sub 2} and chronic exposure to oxidant stress as a result of metabolic redox

  1. Marijuana: interaction with the estrogen receptor.

    PubMed

    Sauer, M A; Rifka, S M; Hawks, R L; Cutler, G B; Loriaux, D L

    1983-02-01

    Crude marijuana extract competed with estradiol for binding to the estrogen receptor of rat uterine cytosol. Condensed marijuana smoke also competed with estradiol for its receptor. Pure delta 9-tetrahydrocannabinol, however, did not interact with the estrogen receptor. Ten delta 9-tetrahydrocannabinol metabolites also failed to compete with estradiol for its receptor. Of several other common cannabinoids tested, only cannabidiol showed any estrogen receptor binding. This was evident only at very high concentrations of cannabidiol. Apigenin, the aglycone of a flavinoid phytoestrogen found in cannabis, displayed high affinity for the estrogen receptor. To assess the biological significance of these receptor data, estrogen activity was measured in vivo with the uterine growth bioassay, using immature rats. Cannabis extract in large doses exhibited neither estrogenic nor antiestrogenic effects. Thus, although estrogen receptor binding activity was observed in crude marijuana extract, marijuana smoke condensate and several known components of cannabis, direct estrogenic activity of cannabis extract could not be demonstrated in vivo.

  2. Mixture interactions of xenoestrogens with endogenous estrogens.

    EPA Science Inventory

    There is growing concern of exposure to fish, wildlife, and humans to water sources contaminated with estrogens and the potential impact on reproductive health. These environmental estrogens originate from various sources including concentrated animal feedlot operations (CAFO), m...

  3. Breast Cancer and Estrogen-Alone Update

    MedlinePlus

    ... Research News From NIH Breast Cancer and Estrogen-Alone Update Past Issues / Summer 2006 Table of Contents ... of this page please turn Javascript on. Estrogen-alone hormone therapy does not increase the risk of ...

  4. Comparative modeling of the latent form of a plant catechol oxidase using a molluskan hemocyanin structure.

    PubMed

    Gerdemann, Carsten; Eicken, Christoph; Galla, Hans Joachim; Krebs, Bernt

    2002-04-10

    The structure of the precursor form of catechol oxidase from sweet potatoes (Ipomoea batatas) has been modeled on the basis of the 3D structural data of mature catechol oxidase [Nat. Struct. Biol. 5 (1998) 1084] and of hemocyanin from giant octopus (Octopus dofleini) [J. Mol. Biol. 278 (1998) 855]. A C-terminal extension peptide is found in the cDNA sequence but not in the purified, mature form of catechol oxidase. Superimposition of the 3D structures of the native hemocyanin and catechol oxidase reveals a close relationship except for an additional C-terminal domain only found in the hemocyanin structure. As sequence alignment shows good homology this domain of the hemocyanin structure was used as a template to model the 3D structure of the C-terminal extension peptide of catechol oxidase. As hemocyanins show no or only weak catecholase activity due to this domain this indicates an inhibitory function of this extension peptide. Beside this possible shielding function for the precursor form, evidence for a function in copper-uptake also increases due to the location of three histidine residues in the model. PMID:11931976

  5. Relation Between the Adsorbed Quantity and the Immersion Enthalpy in Catechol Aqueous Solutions on Activated Carbons

    PubMed Central

    Moreno-Piraján, Juan Carlos; Blanco, Diego; Giraldo, Liliana

    2012-01-01

    An activated carbon, CarbochemTM—PS230, was modified by chemical and thermal treatment in flow of H2, in order to evaluate the influence of the activated carbon chemical characteristics in the adsorption of the catechol. The catechol adsorption in aqueous solution was studied along with the effect of the pH solution in the adsorption process of modified activated carbons and the variation of immersion enthalpy of activated carbons in the aqueous solutions of catechol. The interaction solid-solution is characterized by adsorption isotherms analysis, at 298 K and pH 7, 9 and 11 in order to evaluate the adsorption value above and below that of the catechol pKa. The adsorption capacity of carbons increases when the solution pH decreases. The retained amount increases slightly in the reduced carbon to maximum adsorption pH and diminishes in the oxidized carbon. Similar conclusions are obtained from the immersion enthalpies, whose values increase with the solute quantity retained. In granular activated carbon (CAG), the immersion enthalpies obtained are between 21.5 and 45.7 J·g−1 for catechol aqueous solutions in a range of 20 at 1500 mg·L−1. PMID:22312237

  6. Surface Complexation at the TiO(2) (anatase)/Aqueous Solution Interface: Chemisorption of Catechol.

    PubMed

    Rodríguez; Blesa; Regazzoni

    1996-01-15

    Catechol adsorbs at the TiO(2) (anatase)/aqueous solution interface forming inner-sphere surface complexes. The UV-visible differential reflectance spectrum of surface titanium-catecholate complexes presents a band centered at 420 nm which corresponds to the ligand to metal charge transfer transition within the surface complexes. At pH values below pK(a1), the surface excess of catechol is almost insensitive toward pH and presents a Langmuirian dependence with the concentration of uncomplexed catechol. The ratio Gamma(max):N(S) (N(S) being the measured density of available OH surface groups) indicates a prevailing 1 to 2 ligand exchange adsorption stoichiometry. In the range pH >/= pK(a1), the catechol surface excess decreases markedly with increasing pH. Formation of 1 to 1 surface complexes produces an excess of negative surface charge that is revealed by the shift of the iep to lower pH values. The reported data, which are supplemented with information on the charging behavior of TiO(2) suspended in indifferent electrolyte solutions, are interpreted in terms of the multi-site surface complexation model. In this model, two types of surface OH groups are considered: identical withTiOH(1/3-) and identical withOH(1/3+). Although both surface groups undergo protonation-deprotonation reactions, only identical withTiOH(1/3-) are prone to chemisorption.

  7. Simultaneous determination of hydroquinone and catechol at gold nanoparticles mesoporous silica modified carbon paste electrode.

    PubMed

    Tashkhourian, J; Daneshi, M; Nami-Ana, F; Behbahani, M; Bagheri, A

    2016-11-15

    A new electrochemical sensor based on gold nanoparticles mesoporous silica modified carbon paste electrode (AuNPs-MPS) was developed for simultaneous determination of hydroquinone and catechol. Morphology and structure of the AuNPs-MPS were characterized by transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The electrochemical behavior of hydroquinone and catechol were investigated using square wave voltammetry and the results indicate that the electrochemical responses are improved significantly at the modified electrode. The observed oxidative peaks separation of about 120mV made possible the simultaneous determination of hydroquinone and catechol in their binary-mixture. Under the optimized condition, a linear dynamic range of 10.0μM-1.0mM range for hydroquinone with the detection limit of 1.2μM and from 30.0μM-1.0mM for catechol with the detection limit of 1.1μM were obtained. The applicability of the method was demonstrated by the recovery studies of hydroquinone and catechol in spiked tap water samples. PMID:27420383

  8. Catechol and humic acid sorption onto a range of laboratory-produced black carbons (biochars).

    PubMed

    Kasozi, Gabriel N; Zimmerman, Andrew R; Nkedi-Kizza, Peter; Gao, Bin

    2010-08-15

    Although the major influence of black carbon (BC) on soil and sediment organic contaminant sorption is widely accepted, an understanding of the mechanisms and natural variation in pyrogenic carbon interaction with natural organic matter (NOM) is lacking. The sorption of a phenolic NOM monomer (catechol) and humic acids (HA) onto BC was examined using biochars made from oak, pine, and grass at 250, 400, and 650 degrees C. Catechol sorption equilibrium occurred after 14 d and was described by a diffusion kinetic model, while HA required only 1 d and followed pseudo-second-order kinetics. Catechol sorption capacity increased with increasing biochar combustion temperature, from pine < oak < grass and from coarse < fine particle size. At lower catechol concentrations, sorption affinity (Freundlich constant, K(f)) was directly related to micropore surface area (measured via CO(2) sorptometry) indicating the predominance of specific adsorption. In contrast, HA exhibited an order of magnitude less sorption (0.1% versus 1%, by weight) due to its exclusion from micropores. Greater sorption of both catechol and HA occurred on biochars with nanopores, i.e. biochars made at higher temperatures. These findings suggest that addition of BC to soil, via natural fires or biochar amendments, will sequester abundant native OM through sorption. PMID:20669904

  9. Comparative modeling of the latent form of a plant catechol oxidase using a molluskan hemocyanin structure.

    PubMed

    Gerdemann, Carsten; Eicken, Christoph; Galla, Hans Joachim; Krebs, Bernt

    2002-04-10

    The structure of the precursor form of catechol oxidase from sweet potatoes (Ipomoea batatas) has been modeled on the basis of the 3D structural data of mature catechol oxidase [Nat. Struct. Biol. 5 (1998) 1084] and of hemocyanin from giant octopus (Octopus dofleini) [J. Mol. Biol. 278 (1998) 855]. A C-terminal extension peptide is found in the cDNA sequence but not in the purified, mature form of catechol oxidase. Superimposition of the 3D structures of the native hemocyanin and catechol oxidase reveals a close relationship except for an additional C-terminal domain only found in the hemocyanin structure. As sequence alignment shows good homology this domain of the hemocyanin structure was used as a template to model the 3D structure of the C-terminal extension peptide of catechol oxidase. As hemocyanins show no or only weak catecholase activity due to this domain this indicates an inhibitory function of this extension peptide. Beside this possible shielding function for the precursor form, evidence for a function in copper-uptake also increases due to the location of three histidine residues in the model.

  10. Ortho-substituted catechol derivatives: the effect of intramolecular hydrogen-bonding pathways on chloride anion recognition.

    PubMed

    Winstanley, Keith J; Smith, David K

    2007-04-13

    This paper reports a series of chloride anion receptors containing two catechol head groups connected through their ortho-positions via a spacer chain. The linking group chosen to attach the spacer chain to the catechol units has a major impact on the anion-binding potential of the receptor. Linking groups that are capable of forming stable six-membered intramolecular hydrogen-bonded rings with the catechol O-H groups significantly inhibit the ability of the catechol units to hydrogen bond to chloride anions. However, where the linking groups are only capable of forming five- or seven-membered intramolecular hydrogen-bonded rings, then anion binding via hydrogen bonding through the catechol O-H groups becomes a possibility. This process is solvent dependent; the presence of competitive solvent (e.g., DMSO-d6) disrupts the intramolecular hydrogen-bonding pattern and enhances anion binding relative to simple unfunctionalized catechol. The most effective receptor is that in which the hydrogen-bonding linker (-CH2CONH-) is most distant from the catechol units and can only form a seven-membered intramolecular hydrogen-bonded ring. In this case, the receptor, which contains two catechol units, is a more effective chloride anion binder than simple unfunctionalized catechol, demonstrating that the two head groups, in combination with the N-H groups in the linker, act cooperatively and enhance the degree of anion binding. In summary, this paper provides insight into the hydrogen-bonding patterns in ortho-functionalized catechols and the impact these have on the potential of the catechol O-H groups to hydrogen bond to a chloride anion.

  11. Catechol-O-methyltransferase association with hemoglobin A1c

    PubMed Central

    Hall, Kathryn T.; Jablonski, Kathleen A.; Chen, Ling; Harden, Maegan; Tolkin, Benjamin R.; Kaptchuk, Ted J.; Bray, George A.; Ridker, Paul M.; Florez, Jose C.; Chasman, Daniel I.

    2016-01-01

    Aims Catecholamines have metabolic effects on blood pressure, insulin sensitivity and blood glucose. Genetic variation in catechol-O-methyltransferase (COMT), an enzyme that degrades catecholamines, is associated with cardiometabolic risk factors and incident cardiovascular disease (CVD). Here we examined COMT effects on glycemic function and type 2 diabetes. Methods We tested whether COMT polymorphisms were associated with baseline HbA1c in the Women’s Genome Health Study (WGHS), and Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC), and with susceptibility to type 2 diabetes in WGHS, DIAbetes Genetics Replication And Meta-analysis consortium (DIAGRAM), and the Diabetes Prevention Program (DPP). Given evidence that COMT modifies some drug responses, we examined association with type 2 diabetes and randomized metformin and aspirin treatment. Results COMT rs4680 high-activity G-allele was associated with lower HbA1c in WGHS (β = −0.032% [0.012], p = 0.008) and borderline significant in MAGIC (β = −0.006% [0.003], p = 0.07). Combined COMT per val allele effects on type 2 diabetes were significant (OR = 0.98 [0.96–0.998], p = 0.03) in fixed-effects analyses across WGHS, DIAGRAM, and DPP. Similar results were obtained for 2 other COMT SNPs rs4818 and rs4633. In the DPP, the rs4680 val allele was borderline associated with lower diabetes incidence among participants randomized to metformin (HR = 0.81 [0.65–1.00], p = 0.05). Conclusions COMT rs4680 high-activity G-allele was associated with lower HbA1c and modest protection from type 2 diabetes. The directionality of COMT associations was concordant with those previously observed for cardiometabolic risk factors and CVD. PMID:27282867

  12. A Hyperactive Cobalt-Substituted Extradiol-Cleaving Catechol Dioxygenase

    PubMed Central

    Fielding, Andrew J.; Farquhar, Erik R.

    2011-01-01

    Homoprotocatechuate (HPCA) 2,3-dioxygenase from Brevibacterium fuscum (Fe-HPCD) has an Fe(II) center in its active site that can be replaced with Mn(II) or Co(II). While Mn-HPCD exhibits steady state kinetic parameters comparable to those of Fe-HPCD, Co-HPCD behaves somewhat differently exhibiting a significantly higher KMO2 and kcat. The high activity of Co-HPCD is surprising, given that cobalt has the highest standard M(III/II) redox potential of the three metals. Comparison of the X-ray crystal structures of the resting and substrate-bound forms of Fe-, Mn-, and Co-HPCD shows that metal-substitution has no effect on the local ligand environment, the conformational integrity of the active site, or the overall protein structure, suggesting that the protein structure does not differentially tune the potential of the metal center. Analysis of the steady state kinetics of Co-HPCD suggests that the Co(II) center alters the relative rate constants for the interconversion of intermediates in the catalytic cycle but still allows the dioxygenase reaction to proceed efficiently. When compared with the kinetic data for Fe- and Mn-HPCD, these results show that dioxygenase catalysis can proceed at high rates over a wide range of metal redox potentials. This is consistent with the proposed mechanism in which the metal mediates electron transfer between the catechol substrate and O2 to form the postulated [M(II)(semiquinone)superoxo] reactive species. These kinetic differences and the spectroscopic properties of Co-HPCD provide new tools with which to explore the unique O2 activation mechanism associated with the extradiol dioxygenase family. PMID:21153851

  13. Estrogen actions in the cardiovascular system.

    PubMed

    Mendelsohn, M E

    2009-01-01

    This brief review summarizes the current state of the field for estrogen receptor actions in the cardiovascular system and the cardiovascular effects of hormone replacement therapy (HRT). It is organized into three parts: a short Introduction and overview of the current view of how estrogen works on blood vessels; a summary of the current status of clinical information regarding HRT and cardiovascular effects; and an update on state-of-the-art mouse models of estrogen action using estrogen receptor knockout mice.

  14. Synthesis, structure, spectra and reactivity of iron(III) complexes of facially coordinating and sterically hindering 3N ligands as models for catechol dioxygenases.

    PubMed

    Sundaravel, Karuppasamy; Dhanalakshmi, Thirumanasekaran; Suresh, Eringathodi; Palaniandavar, Mallayan

    2008-12-28

    A series of 1 : 1 iron(III) complexes of sterically hindered and systematically modified tridentate 3N donor ligands have been isolated and studied as functional models for extradiol-cleaving catechol dioxygenases. All of them are of the type [Fe(L)Cl(3)], where L is N-methyl-N'-(pyrid-2-ylmethyl)ethylenediamine (L1), N-ethyl-N'-(pyrid-2-ylmethyl)ethylenediamine (L2), N-benzyl-N'-(pyrid-2-ylmethyl)ethylenediamine (L3), N,N-dimethyl-N'-(pyrid-2-ylmethyl)ethylenediamine (L4), N'-methyl-N'-(pyrid-2-ylmethyl)-N,N-dimethylethylenediamine (L5), N'-ethyl-N'-(pyrid-2-ylmethyl)-N,N-dimethylethylenediamine (L6) and N'-benzyl-N'-(pyrid-2-ylmethyl)-N,N-dimethylethylenediamine (L7). They have been characterized by elemental analysis and spectral and electrochemical methods. The X-ray crystal structures of the complexes [Fe(L2)Cl(3)] 2, [Fe(L3)Cl(3)] 3 and [Fe(L7)Cl(3)] 7 have been successfully determined. All the three complexes possess a distorted octahedral coordination geometry in which the ligand is facially coordinated to iron(III) and the chloride ions occupy the remaining coordination sites. Upon replacing the N-ethyl group on the terminal nitrogen donor in 2 by the bulky N-benzyl group as in 3, the terminal Fe-N bond distance increases slightly from 2.229(5) A to 2.244(5) A. Upon incorporating the sterically demanding N-benzyl group on the central nitrogen donor in 4 to obtain 7, the central Fe-N(amine) bond distance increases from 2.181(5) A to 2.299(2) A. The catecholate adducts [Fe(L)(DBC)(Cl)] and [Fe(L)(DBC)(Sol)](+), where H(2)DBC is 3,5-di-tert-butylcatechol and Sol = solvent (H(2)O/DMF), have been generated in situ and their spectral and redox properties and dioxygenase activities have been studied in N,N-dimethylformamide and dichloromethane solutions. The adducts [Fe(L)(DBC)(Sol)](+) undergo cleavage of DBC(2-) in the presence of molecular oxygen to afford both intra- and extradiol cleavage products. The extradiol products are higher in dichloromethane than in

  15. Role of 2-methoxyestradiol, an Endogenous Estrogen Metabolite, in Health and Disease.

    PubMed

    Parada-Bustamante, Alexis; Valencia, Cecilia; Reuquen, Patricia; Diaz, Patricia; Rincion-Rodriguez, Ramiro; Orihuela, Pedro A

    2015-01-01

    Estradiol (E2) is a steroid hormone whose physiological actions are mainly mediated by its interaction with intracellular estrogen receptors (ER) leading to modification on the mRNA and protein synthesis in its target cells. However, estrogens can also activate several intracellular signal transduction cascades by non-genomic mechanisms. Estrogens must be inactivated and removed from blood through its conversion to soluble compounds with an apparent low estrogenic activity and decreased affinity for ER. In this context, 2-methoxyestradiol (2ME2) is generated by a sequential hydroxylation of E2 via the enzyme cytochrome P450 isoform 1A1 to produce 2-hydroxyestradiol (2OHE2) followed by a conjugation reaction catalyzed by the enzyme Catechol-O-Methyltransferase generating 2ME2 from 2OHE2. Recent evidence indicates that physiological concentration of 2ME2 may regulate several biological processes while high concentrations of this metabolite may induce pathophysiological alterations in several tissues. In the last years, 2ME2 has also been described as a promising anticancer drug although its cellular and molecular mechanisms are still being disclosed. Herein, we will review the available literature concerning the role of 2ME2 in health and disease. We will focus on to describing the intracellular mechanisms by which 2ME2 exerts its effects on reproductive and non-reproductive tissues. The promising anticancer effects of 2ME2 and its synthetic derivatives will also be discussed. Finally, a group of 2ME2-target genes that could be used as biomarkers of 2ME2 under physiological or pathophysiological conditions will be reviewed.

  16. [Role of estrogen in male reproduction].

    PubMed

    Pan, Yi-Qing; Xu, Chen

    2005-11-01

    Estrogen plays an essential role in male reproduction. In human and other mammalians, a number of tissues express aromatase and hence synthesize estrogen. ERs and aromatase are present at all developmental stages of the male reproductive organs in many mammalian species. Estrogen is important in different aspects in male reproductive physiology, including its effects on germ cells, Sertoli cells, Leydig cells and epididymal functions.

  17. Purification and spectroscopic studies on catechol oxidase from lemon balm (Melissa officinalis).

    PubMed

    Rompel, Annette; Büldt-Karentzopoulos, Klaudia; Molitor, Christian; Krebs, Bernt

    2012-09-01

    A catechol oxidase from lemon balm (Melissa officinalis) moCO which only catalyzes the oxidation of catechols to quinones without hydroxylating tyrosine was purified. The molecular mass of the M. officinalis enzyme of 39,370 Da was obtained by MALDI mass spectrometry and the isoelectric point was determined to be 3.4. Addition of 2 eq. H(2)O(2) to the enzyme leads to oxy catechol oxidase. In the UV/Vis spectrum two new absorption bands occur at 343 nm (ε=8510 M(-1)cm(-1)) and 580 nm (ε=580 M(-1)cm(-1)) due to O(2)(2-)Cu (II) charge transfer transitions in accordance with the oxy forms of other type 3 copper proteins. The N-terminal sequence has been determined by Edman degradation to NPVQAPELDKCGTAT, exhibiting a proline at the second and sixth position conserved in other polyphenol oxidases. PMID:22727580

  18. Effect of β-cyclodextrin on intra and intermolecular Michael addition of some catechol derivatives.

    PubMed

    Khalafi, Lida; Rafiee, Mohammad; Fathi, Sahar

    2014-01-24

    The oxidation reactions of catechol, dopamine and epinephrine have been studied in the absence and presence of N-methylaniline by UV-Vis. Spectrophotometry. A variety of reaction pathways (inter and intramolecular reactions) that followed by this oxidation have been observed depending on the nature of catechol derivatives. The observed homogeneous rate constants of the reactions were estimated by fitting the absorption time profiles for each reaction. The effect of β-cyclodextrin and its inclusion complex has also been studied on the chosen reactions. The formation constants of the complexes of catechol, dopamine and epinephrine with β-cyclodextrin as well as the rate constants of the reactions of free and complexed forms have been obtained by fitting the absorption-time spectra to a proposed kinetic-equilibrium model.

  19. Catechols as Sources of Hydrogen Atoms in Radical Deiodination and Related Reactions.

    PubMed

    Povie, Guillaume; Ford, Leigh; Pozzi, Davide; Soulard, Valentin; Villa, Giorgio; Renaud, Philippe

    2016-09-01

    When used with trialkylboranes, catechol derivatives, which are low-cost and low toxicity, are valuable hydrogen atom donors for radical chain reactions involving alkyl iodides and related radical precursors. The system 4-tert-butylcatechol/triethylborane has been used to reduce a series of secondary and tertiary iodides, a xanthate, and a thiohydroxamate ester. Catechol derivatives are right in the optimal kinetic window for synthetic applications, as demonstrated by highly efficient radical cyclizations. Cyclizations leading to the formation of quaternary centers can be performed in an all-at-once process (no slow addition of the hydrogen atom donor) at standard concentrations. The H-donor properties of catechol derivatives can be fine-tuned by changing their substitution pattern. In slow radical cyclization processes, an enhanced ratio of cyclized/uncyclized products was obtained by using 3-methoxycatechol instead of 4-tert-butylcatechol.

  20. Effect of β-cyclodextrin on intra and intermolecular Michael addition of some catechol derivatives

    NASA Astrophysics Data System (ADS)

    Khalafi, Lida; Rafiee, Mohammad; Fathi, Sahar

    2014-01-01

    The oxidation reactions of catechol, dopamine and epinephrine have been studied in the absence and presence of N-methylaniline by UV-Vis. Spectrophotometry. A variety of reaction pathways (inter and intramolecular reactions) that followed by this oxidation have been observed depending on the nature of catechol derivatives. The observed homogeneous rate constants of the reactions were estimated by fitting the absorption time profiles for each reaction. The effect of β-cyclodextrin and its inclusion complex has also been studied on the chosen reactions. The formation constants of the complexes of catechol, dopamine and epinephrine with β-cyclodextrin as well as the rate constants of the reactions of free and complexed forms have been obtained by fitting the absorption-time spectra to a proposed kinetic-equilibrium model.

  1. Purification and spectroscopic studies on catechol oxidase from lemon balm (Melissa officinalis).

    PubMed

    Rompel, Annette; Büldt-Karentzopoulos, Klaudia; Molitor, Christian; Krebs, Bernt

    2012-09-01

    A catechol oxidase from lemon balm (Melissa officinalis) moCO which only catalyzes the oxidation of catechols to quinones without hydroxylating tyrosine was purified. The molecular mass of the M. officinalis enzyme of 39,370 Da was obtained by MALDI mass spectrometry and the isoelectric point was determined to be 3.4. Addition of 2 eq. H(2)O(2) to the enzyme leads to oxy catechol oxidase. In the UV/Vis spectrum two new absorption bands occur at 343 nm (ε=8510 M(-1)cm(-1)) and 580 nm (ε=580 M(-1)cm(-1)) due to O(2)(2-)Cu (II) charge transfer transitions in accordance with the oxy forms of other type 3 copper proteins. The N-terminal sequence has been determined by Edman degradation to NPVQAPELDKCGTAT, exhibiting a proline at the second and sixth position conserved in other polyphenol oxidases.

  2. Multimodal underwater adsorption of oxide nanoparticles on catechol-based polymer nanosheets

    NASA Astrophysics Data System (ADS)

    Yamamoto, Shunsuke; Uchiyama, Shun; Miyashita, Tokuji; Mitsuishi, Masaya

    2016-03-01

    Multimodal underwater adsorption behaviour of catechol units was demonstrated by examining the adsorption of different oxide nanoparticles on nanoscale-integrated polymer nanosheets. Catechol-based polymer nanosheets were fabricated using the Langmuir-Blodgett (LB) technique with random copolymers (p(DDA/DMA)s) of N-dodecylacrylamide (DDA) and dopamine methacrylamide (DMA). The p(DDA/DMA) nanosheets were immersed into water dispersions of SiO2, Al2O3, and WO3 nanoparticles (NPs) respectively. The results show that the adsorption properties can be altered by varying the NP type: SiO2 NP adsorption was observed only below pH = 6, at which the o-quinone form in p(DDA/DMA) nanosheets transforms into the catechol form or vice versa. However, their transition point for Al2O3 NP adsorption was found at approximately pH 10, at which the surface potential of Al2O3 NPs changes the charge polarity, indicating that the electrostatic interaction is predominant. For WO3 NPs, adsorption was observed when citric acid, which modifies the surface of WO3 NPs by complex formation, was used as a pH-controlling agent, but no adsorption was found for hydrochloric acid used as a pH controlling agent. FT-IR measurements proved that miniscule amounts of water molecules were trapped in p(DDA/DMA) nanosheets and that they acquired hydrogen bonding network formations, which might assist nanoparticle adsorption underwater and make the catechol units adjustable. The results indicate that the nanoscale spatial arrangements of catechol units in films are crucially important for the application of multimodal adsorption of oxide nanoparticles on catechol-based polymer materials.Multimodal underwater adsorption behaviour of catechol units was demonstrated by examining the adsorption of different oxide nanoparticles on nanoscale-integrated polymer nanosheets. Catechol-based polymer nanosheets were fabricated using the Langmuir-Blodgett (LB) technique with random copolymers (p(DDA/DMA)s) of N

  3. [Kinetics of the catalytic oxidation of catechol in aqueous solutions of ceruloplasmin in the presence of Fe3+].

    PubMed

    Vorotyntsev, V M; Biriukovich, O K; Piatnitskiĭ, Iu I; Golodets, G I; Kachorovskiĭ, B V

    1982-03-01

    The kinetics of oxidation of catechol in aqueous solutions containing ceruloplasmin and Fe3+, were studied. It was found that Fe3+ at low concentrations accelerate the reaction. The inhibiting effect of high concentrations of Fe3+ is due to the formation of catalytically inactive enzyme complexes with catechol oxidation products. A mechanism of this process is proposed.

  4. A natural small molecule, catechol, induces c-Myc degradation by directly targeting ERK2 in lung cancer

    PubMed Central

    Lim, Do Young; Shin, Seung Ho; Lee, Mee-Hyun; Malakhova, Margarita; Kurinov, Igor; Wu, Qiong; Xu, Jinglong; Jiang, Yanan; Dong, Ziming; Liu, Kangdong; Lee, Kun Yeong; Bae, Ki Beom; Choi, Bu Young; Deng, Yibin; Bode, Ann; Dong, Zigang

    2016-01-01

    Various carcinogens induce EGFR/RAS/MAPK signaling, which is critical in the development of lung cancer. In particular, constitutive activation of extracellular signal-regulated kinase 2 (ERK2) is observed in many lung cancer patients, and therefore developing compounds capable of targeting ERK2 in lung carcinogenesis could be beneficial. We examined the therapeutic effect of catechol in lung cancer treatment. Catechol suppressed anchorage-independent growth of murine KP2 and human H460 lung cancer cell lines in a dose-dependent manner. Catechol inhibited ERK2 kinase activity in vitro, and its direct binding to the ERK2 active site was confirmed by X-ray crystallography. Phosphorylation of c-Myc, a substrate of ERK2, was decreased in catechol-treated lung cancer cells and resulted in reduced protein stability and subsequent down-regulation of total c-Myc. Treatment with catechol induced G1 phase arrest in lung cancer cells and decreased protein expression related to G1-S progression. In addition, we showed that catechol inhibited the growth of both allograft and xenograft lung cancer tumors in vivo. In summary, catechol exerted inhibitory effects on the ERK2/c-Myc signaling axis to reduce lung cancer tumor growth in vitro and in vivo, including a preclinical patient-derived xenograft (PDX) model. These findings suggest that catechol, a natural small molecule, possesses potential as a novel therapeutic agent against lung carcinogenesis in future clinical approaches. PMID:27167001

  5. Iron(III) complexes of N2O and N3O donor ligands as functional models for catechol dioxygenase enzymes: ether oxygen coordination tunes the regioselectivity and reactivity.

    PubMed

    Sundaravel, Karuppasamy; Suresh, Eringathodi; Saminathan, Kolandaivel; Palaniandavar, Mallayan

    2011-08-28

    A series of mononuclear iron(III) complexes of the type [Fe(L)Cl(3)], where L is a systematically modified N(2)O or N(3)O ligand with a methoxyethyl/tetrahydrofuryl ether oxygen donor atom, have been isolated and studied as models for catechol dioxygenases. The X-ray crystal structures of [Fe(L2)Cl(3)] 2, [Fe(L6)Cl(3)] 6, [Fe(L5)(TCC)Cl] 5a, where H(2)TCC = tetrachlorocatechol, [Fe(L6)(TCC)Br] 6a, and the μ-oxo dimer [{Fe(L6)Cl}(2)O](ClO(4))(2) 6b have been successfully determined. In [Fe(L2)Cl(3)] 2 the N(2)O ligand is facially coordinated to iron(III) through the pyridine and secondary amine nitrogen atoms and the tetrahydrofuryl oxygen atom. In [Fe(L6)Cl(3)] 6, [Fe(L5)(TCC)Cl] 5a and [Fe(L6)(TCC)Br] 6a the N(3)O donor ligands L5 and L6 act as a tridentate N3 donor ligand coordinated through two pyridine and one secondary amine nitrogen atoms, whereas the ether oxygen is not coordinated. The spectral and electrochemical properties of the adducts [Fe(L)(DBC)Cl] of 1-8, where H(2)DBC = 3,5-di-tert-butylcatechol, in DMF and their solvated adduct species [Fe(L)(DBC)(Sol)](+), where Sol = DMF/H(2)O, generated in situ in dichloromethane, respectively, have been investigated. The product analysis demonstrates that the adducts [Fe(L)(DBC)Cl] effect cleavage of catechol in the presence of O(2) in DMF to give mainly the intradiol (I) product with a small amount of the extradiol (E) product (E/I, 0.2:1-0.7:1). Interestingly, the solvated species [Fe(L)(DBC)(Sol)](+) derived from 1-4 cleave H(2)DBC to provide mainly the extradiol cleavage products with lower amounts of intradiol products (E/I, 2.3:1-4.3:1) in dichloromethane. In contrast, the solvated species [Fe(L)(DBC)(Sol)](+) derived from 5-8 cleave H(2)DBC to provide both extradiol and intradiol products (E/I, 0.6:1-2.3:1) due to the involvement of the ether oxygen donor of the methoxyethyl/tetrahydrofuryl arm in the coordination to iron(III) upon removal of a chloride ion. PMID:21766098

  6. Stability of acetaldehyde-derived DNA adduct in vitro.

    PubMed

    Hori, Kimiko; Miyamoto, Shin'ichi; Yukawa, Yoshiyuki; Muto, Manabu; Chiba, Tsutomu; Matsuda, Tomonari

    2012-07-13

    Acetaldehyde (AA) derived from alcoholic beverages is a confirmed carcinogen for esophageal and head and neck cancers. AA forms various DNA adducts and is thought to play a crucial role in carcinogenesis. Transient DNA adducts are usually repaired, but the stability of AA-derived DNA adducts has not been elucidated. We investigated the stability of N(2)-ethylidene-2'-deoxyguanosine (N(2)-ethylidene-dG), a major AA-derived DNA adduct, in cultured cells. First, to determine the optimal concentration of AA for detecting N(2)-ethylidene-dG in cell culture, a dose-response study was performed using HL60 cells of the human promyelocytic leukemia cell line. An AA concentration ≥ 0.01% (1.8 mM) was required to detect N(2)-ethylidene-dG in vitro. We next examined the stability of N(2)-ethylidene-dG. After a 1 or 2h exposure to 0.01% of AA in a tightly sealed bottle, N(2)-ethylidene-dG content was measured by sensitive liquid chromatography tandem mass spectrometry immediately, 24h, and 48 h after exposure. After the 1h exposure, the mean (± SD) N(2)-ethylidene-dG contents were 12.1 ± 1.28, 8.20 ± 0.64, and 6.70 ± 0.52 adducts per 10(7) bases at each postexposure time. After the 2h exposure, N(2)-ethylidene-dG content increased to 21.4 ± 7.50, 10.5 ± 3.61, and 9.83 ± 3.90 adducts per 10(7) bases at each postexposure time. The half-life of this adduct was calculated as ∼35 h in independent experiments. These results indicate that AA exposure from daily alcohol consumption may cause DNA damage and may increase the risk of alcohol-related carcinogenesis. PMID:22683642

  7. The effect of catechol on human peripheral blood mononuclear cells (in vitro study).

    PubMed

    Bukowska, Bożena; Michałowicz, Jaromir; Marczak, Agnieszka

    2015-01-01

    Catechol also known as pyrocatechol or 1,2-dihydroxybenzene is formed endogenously in the organism from neurotransmitters including adrenaline, noradrenaline, and dopamine. It is also a metabolite of many drugs like DOPA, isoproterenol or aspirin and it is also formed in the environment during transformation of various xenobiotics. We evaluated in vitro the effect of catechol on the structure and function of human peripheral blood mononuclear cells (PBMCs). The cells were incubated with xenobiotic at concentration range from 2 to 500μg/mL for 1h. Human blood mononuclear cells were obtained from leucocyte-platelet buffy coat taken from healthy donors in the Blood Bank of Łódź, Poland. Using flow cytometry we have evaluated necrotic, apoptotic and morphological changes in PBMCs incubated with catechol. Moreover, we have estimated changes in reactive oxygen species (ROS) formation, protein carbonylation and lipid peroxidation in the cells studied. The compound studied provoked necrotic (from 250μg/mL), apoptotic (from 100μg/mL), and morphological changes (from 250μg/mL) in the incubated cells. We have also noted that catechol decreased H2DCF oxidation at 2 and 10μg/mL but at higher concentrations of 250 and 500μg/mL it caused statistically significant increase in the oxidation of this probe. We also observed an increase in lipid peroxidation (from 250μg/mL) and protein carbonylation (from 50μg/mL) of PBMCs. It was observed that catechol only at high concentrations was capable of inducing changes in PBMCs. The obtained results clearly showed that catechol may induce change in PBMCs only in the caste of poisoning with this compound. PMID:25528409

  8. Partitioning of knee joint internal forces in gait is dictated by the knee adduction angle and not by the knee adduction moment.

    PubMed

    Adouni, M; Shirazi-Adl, A

    2014-05-01

    Medial knee osteoarthritis is a debilitating disease. Surgical and conservative interventions are performed to manage its progression via reduction of load on the medial compartment or equivalently its surrogate measure, the external adduction moment. However, some studies have questioned a correlation between the medial load and adduction moment. Using a musculoskeletal model of the lower extremity driven by kinematics-kinetics of asymptomatic subjects at gait midstance, we aim here to quantify the relative effects of changes in the knee adduction angle versus changes in the adduction moment on the joint response and medial/lateral load partitioning. The reference adduction rotation of 1.6° is altered by ±1.5° to 3.1° and 0.1° or the knee reference adduction moment of 17Nm is varied by ±50% to 25.5Nm and 8.5Nm. Quadriceps, hamstrings and tibiofemoral contact forces substantially increased as adduction angle dropped and diminished as it increased. The medial/lateral ratio of contact forces slightly altered by changes in the adduction moment but a larger adduction rotation hugely increased this ratio from 8.8 to a 90 while in contrast a smaller adduction rotation yielded a more uniform distribution. If the aim in an intervention is to diminish the medial contact force and medial/lateral load ratio, a drop of 1.5° in adduction angle is much more effective (causing respectively 12% and 80% decreases) than a reduction of 50% in the adduction moment (causing respectively 4% and 13% decreases). Substantial role of changes in adduction angle is due to the associated alterations in joint nonlinear passive resistance. These findings explain the poor correlation between knee adduction moment and tibiofemoral compartment loading during gait suggesting that the internal load partitioning is dictated by the joint adduction angle.

  9. Intramolecular interactions in ortho-methoxyalkylphenylboronic acids and their catechol esters

    NASA Astrophysics Data System (ADS)

    Adamczyk-Woźniak, Agnieszka; Borys, Krzysztof M.; Czerwińska, Karolina; Gierczyk, Błażej; Jakubczyk, Michał; Madura, Izabela D.; Sporzyński, Andrzej; Tomecka, Ewelina

    2013-12-01

    Catechol esters of ortho-methoxyalkylphenylboronic acids have been synthesized and characterized by 17O NMR spectroscopy. The results were compared with the data for the parent acids. The influence of intramolecular and intermolecular hydrogen bonds on the properties of the boronic acids has been discussed. The 17O NMR data for the boronic esters proved that there are no O → B interactions in the investigated compounds. This fact is connected with weak Lewis acidity of the parent acids and their low sugars' receptors activity. Crystal structure of ortho-methoxyphenylboronic acid catechol ester was determined.

  10. Regioselectivity of catechol O-methyltransferase confers enhancement of catalytic activity

    NASA Astrophysics Data System (ADS)

    Tsao, Douglas; Liu, Shubin; Dokholyan, Nikolay V.

    2011-04-01

    Catechol O-methyltransferase (COMT) metabolizes catechol moieties by methylating a single hydroxyl group at the meta- or para- hydroxyl position. Hydrophobic amino acids near the active site of COMT influence the regioselectivity of this reaction. Our sequence analysis highlights their importance by showing that these residues are highly conserved throughout evolution. Reaction barriers calculated in the gas phase reveal a lower barrier during methylation at the meta- position, suggesting that the observed meta-regioselectivity of COMT can be attributed to the substrate itself, and that COMT has evolved residues to orient the substrate in a manner that increases the rate of catalysis.

  11. Estrogens and Male Lower Urinary Tract Dysfunction

    PubMed Central

    Wynder, Jalissa L.; Nicholson, Tristan M.; DeFranco, Donald B.

    2016-01-01

    Benign prostatic hyperplasia (BPH) and associated lower urinary tract symptoms (LUTS) are common clinical problems in urology and affect the majority of men at some time during their lives. The development of BPH/LUTS is associated with an increased ratio of estrogen to androgen levels, and this ratio, when mimicked in a variety of animals, induces BPH and lower urinary tract dysfunction (LUTD). While the precise molecular etiology remains unclear, estrogens have been implicated in the development and maintenance of BPH. Numerous endogenous and exogenous estrogens exist in humans. These estrogens act via multiple estrogen receptors to promote or inhibit prostatic hyperplasia and other BPH-associated processes. The prostate is an estrogen target tissue, and estrogens directly and indirectly affect growth and differentiation of prostate. The precise role of estrogen action directly affecting prostate growth and differentiation in the context of BPH is an understudied area and remains to be elucidated. Estrogens and selective estrogen receptor modulators (SERMs) have been shown to promote or inhibit prostate proliferation illustrating their potential roles in the development of BPH as therapy. More work will be required to identify estrogen signaling pathways associated with LUTD in order to develop more efficacious drugs for BPH treatment and prevention. PMID:26156791

  12. Estrogen mediation of hormone responses to exercise.

    PubMed

    Kraemer, Robert R; Francois, Michelle; Castracane, V Daniel

    2012-10-01

    The roles of estrogens extend from the regulation of reproduction to other functions involved in control of metabolism, fluid balance, as well as gastrointestinal, lung, and brain function, with a strong effect on other hormones that subsequently alter the physiology of multiple tissues. As such, alteration of endogenous estrogens across the menstrual cycle, or from oral contraception and estrogen replacement therapy, can affect these tissues. Due to the important effects that estrogens have on different tissues, there are many investigations concerning the effects of a human estrogenic environment on endocrine responses to exercise. The following review will describe the consequences of varying estrogen levels on pituitary, adrenal, gonadal, and endocrine function, followed by discussion of the outcomes of different estrogen levels on endocrine tissues in response to exercise, problems encountered for interpretation of findings, and recommended direction for future research. PMID:22512823

  13. Pharmacological profile of estrogens in oral contraception.

    PubMed

    Bitzer, J

    2011-06-01

    The synthetic estrogen ethinylestradiol (EE)given by mouth is stable and yields satisfactory results in terms of ovulation inhibition and effects on the endometrium. It increases however the risk especially for venous thrombotic events and to a lesser degree also arterial thrombosis. Therefore research focused on diminuition of the EE dosage and the development of a different estrogen component in oral contraceptives, specifically an estrogen occurring during physiological processes in the female body. Two estrogens emerge: 17ß Estradiol is the most potent natural estrogen and it is the major estrogen secreted by the ovaries. Estetrol is a human sex steroid (15 alpha hydroxyestriol) which is only produced during pregnancy by the fetal liver. The pharmacolokinetic and pharmacodynamic properties of these estrogens are compared to those of EE (absorption, metabolization, bioavailability etc.) and the clinical profile is described as far it is known from a limited number of studies. PMID:21654614

  14. Berries and Ellagic Acid Prevent Estrogen-Induced Mammary Tumorigenesis by Modulating Enzymes of Estrogen Metabolism

    PubMed Central

    Aiyer, Harini S.; Gupta, Ramesh C.

    2010-01-01

    In order to determine whether dietary berries and ellagic acid prevent 17β estradiol (E2) -induced mammary tumors by altering estrogen metabolism, we randomized ACI rats (n=6/group) into 5 groups − sham implant + control diet (SH-CD), E2 − implant + control diet (E2-CD), E2+2.5% black raspberry (E2-BRB); E2+2.5% blueberry (E2-BB) and E2+ 400ppm ellagic acid (E2-EA). Animals were euthanized at early (6wk), intermediate (18wk) and late (24wk) phases of E2-carcinogenesis and the mammary tissue analyzed for gene-expression changes using quantitative real-time PCR. At 6 weeks, E2-treatment caused 48-fold increase in cytochrome P4501A1(CYP1A1) (p<0.0001), which was attenuated by both BRB and BB diets to 12- and 21-fold, respectively (p<0.001). E2 did not alter CYP1B1 levels, but both berry and EA diets significantly suppressed it by 11- and 3.5-fold, respectively from baseline (p<0.05). There was a 5-fold increase in 17β-Hydroxysteroid dehyrdogenase(17βHSD7) and this was moderately abrogated to about 2-fold by all supplementation (p<0.05). At 18 weeks, CYP1A1 was elevated by 15-fold in E2-CD and only E2-BB reduced this increase to 7-fold (p<0.05). Catechol-O-methyl transferase(COMT) expression was elevated 2-fold by E2-treatment (p<0.05) and all supplementation reversed this. At 24 weeks, CYP1A1 expression was less pronounced, but still high (8-fold) in E2-treated rats. This increase was reduced to 3.2 and 4.6-fold, by E2-BRB and E2-EA, respectively (p<0.05), but not by E2-BB. Supplementation did not alter the effect of E2 on steroid receptors. The diets also significantly suppressed mammary tumor incidence (10–30%), volume (41–67%) and multiplicity (38 to 51%) (p<0.05). Berries may prevent mammary tumors by suppressing the levels of E2-metabolizing enzymes during the early phase of E2-carcinogenesis. PMID:20501861

  15. Organocatalytic removal of formaldehyde adducts from RNA and DNA bases.

    PubMed

    Karmakar, Saswata; Harcourt, Emily M; Hewings, David S; Scherer, Florian; Lovejoy, Alexander F; Kurtz, David M; Ehrenschwender, Thomas; Barandun, Luzi J; Roost, Caroline; Alizadeh, Ash A; Kool, Eric T

    2015-09-01

    Formaldehyde is universally used to fix tissue specimens, where it forms hemiaminal and aminal adducts with biomolecules, hindering the ability to retrieve molecular information. Common methods for removing these adducts involve extended heating, which can cause extensive degradation of nucleic acids, particularly RNA. Here, we show that water-soluble bifunctional catalysts (anthranilates and phosphanilates) speed the reversal of formaldehyde adducts of mononucleotides over standard buffers. Studies with formaldehyde-treated RNA oligonucleotides show that the catalysts enhance adduct removal, restoring unmodified RNA at 37 °C even when extensively modified, while avoiding the high temperatures that promote RNA degradation. Experiments with formalin-fixed, paraffin-embedded cell samples show that the catalysis is compatible with common RNA extraction protocols, with detectable RNA yields increased by 1.5-2.4-fold using a catalyst under optimized conditions and by 7-25-fold compared with a commercial kit. Such catalytic strategies show promise for general use in reversing formaldehyde adducts in clinical specimens. PMID:26291948

  16. Structures of oxaliplatin-oligonucleotide adducts from DNA.

    PubMed

    Mowaka, Shereen; Ziehe, Matthias; Mohamed, Dalia; Hochkirch, Ulrike; Thomale, Jürgen; Linscheid, Michael W

    2012-10-01

    Oxaliplatin, [(1R,2R)-cyclohexane-1,2-diamine](ethanedioato-O,O')platinum(II) shows a great efficiency against colorectal cancer. Although the mode of action of oxaliplatin is not yet understood, it is commonly accepted that binding of oxaliplatin to DNA prevents DNA synthesis and alters protein to DNA binding. In order to elucidate the modified DNA-protein interaction and thus to understand the mechanisms leading to cellular misinterpretation of DNA information and apoptosis, we have identified the preferential binding sites and the dynamics of the oxaliplatin-DNA intrastrand and interstrand adducts at the oligomer level using high-performance liquid chromatography/electrospray ionization-tandem mass spectrometry (HPLC/ESI-MS/MS) and HPLC/inductively coupled plasma-MS for quantitative studies. We used a combination of benzonase, alkaline phosphatase and Nuclease S1 for digestion. This digestion procedure allows the study of platinated oligomeric nucleotides and more complex interstrand adducts. The digestion products were mostly chromatographically separated and characterized using HPLC/ESI-ion trap MS/MS experiments. We could show that the adducts to guanine and adenine are quite dynamic; that is, the ratios are changing for several days. In addition, the resulting adducts provide evidence for the action of the digesting enzymes and indicate that the adduct spectrum at the oligomeric level is different to that at the commonly studies dinucleotide level.

  17. Organocatalytic removal of formaldehyde adducts from RNA and DNA bases.

    PubMed

    Karmakar, Saswata; Harcourt, Emily M; Hewings, David S; Scherer, Florian; Lovejoy, Alexander F; Kurtz, David M; Ehrenschwender, Thomas; Barandun, Luzi J; Roost, Caroline; Alizadeh, Ash A; Kool, Eric T

    2015-09-01

    Formaldehyde is universally used to fix tissue specimens, where it forms hemiaminal and aminal adducts with biomolecules, hindering the ability to retrieve molecular information. Common methods for removing these adducts involve extended heating, which can cause extensive degradation of nucleic acids, particularly RNA. Here, we show that water-soluble bifunctional catalysts (anthranilates and phosphanilates) speed the reversal of formaldehyde adducts of mononucleotides over standard buffers. Studies with formaldehyde-treated RNA oligonucleotides show that the catalysts enhance adduct removal, restoring unmodified RNA at 37 °C even when extensively modified, while avoiding the high temperatures that promote RNA degradation. Experiments with formalin-fixed, paraffin-embedded cell samples show that the catalysis is compatible with common RNA extraction protocols, with detectable RNA yields increased by 1.5-2.4-fold using a catalyst under optimized conditions and by 7-25-fold compared with a commercial kit. Such catalytic strategies show promise for general use in reversing formaldehyde adducts in clinical specimens.

  18. Organocatalytic removal of formaldehyde adducts from RNA and DNA bases

    NASA Astrophysics Data System (ADS)

    Karmakar, Saswata; Harcourt, Emily M.; Hewings, David S.; Lovejoy, Alexander F.; Kurtz, David M.; Ehrenschwender, Thomas; Barandun, Luzi J.; Roost, Caroline; Alizadeh, Ash A.; Kool, Eric T.

    2015-09-01

    Formaldehyde is universally used to fix tissue specimens, where it forms hemiaminal and aminal adducts with biomolecules, hindering the ability to retrieve molecular information. Common methods for removing these adducts involve extended heating, which can cause extensive degradation of nucleic acids, particularly RNA. Here, we show that water-soluble bifunctional catalysts (anthranilates and phosphanilates) speed the reversal of formaldehyde adducts of mononucleotides over standard buffers. Studies with formaldehyde-treated RNA oligonucleotides show that the catalysts enhance adduct removal, restoring unmodified RNA at 37 °C even when extensively modified, while avoiding the high temperatures that promote RNA degradation. Experiments with formalin-fixed, paraffin-embedded cell samples show that the catalysis is compatible with common RNA extraction protocols, with detectable RNA yields increased by 1.5-2.4-fold using a catalyst under optimized conditions and by 7-25-fold compared with a commercial kit. Such catalytic strategies show promise for general use in reversing formaldehyde adducts in clinical specimens.

  19. Organocatalytic Removal of Formaldehyde Adducts from RNA and DNA Bases

    PubMed Central

    Karmakar, Saswata; Harcourt, Emily M.; Hewings, David S.; Lovejoy, Alexander F.; Kurtz, David M.; Ehrenschwender, Thomas; Barandun, Luzi J.; Roost, Caroline; Alizadeh, Ash A.; Kool, Eric T.

    2015-01-01

    Formaldehyde is universally employed to fix tissue specimens, where it forms hemiaminal and aminal adducts with biomolecules, hindering the ability to retrieve molecular information. Common methods for removing these adducts involve extended heating, which can cause extensive degradation of nucleic acids, particularly RNA. Here we show that water-soluble bifunctional catalysts (anthranilates and phosphanilates) speed the reversal of formaldehyde adducts of mononucleotides over standard buffers. Studies with formaldehyde-treated RNA oligonucleotides show that the catalysts enhance adduct removal, restoring unmodified RNA at 37 °C even when extensively modified, and avoiding high temperatures that promote RNA degradation. Experiments with formalin-fixed, paraffin-embedded cell samples show that the catalysis is compatible with common RNA extraction protocols, with detectable RNA yields increased by 1.5–2.4 fold using a catalyst under optimized conditions, and by 7–25 fold compared to a commercial kit. Such catalytic strategies show promise for general use in reversing formaldehyde adducts in clinical specimens. PMID:26291948

  20. Nongenomic effects of estrogen mediate the dose-related myocardial oxidative stress and dysfunction caused by acute ethanol in female rats

    PubMed Central

    El-Mas, Mahmoud M.

    2013-01-01

    Acute ethanol lowers blood pressure (BP) and cardiac output in proestrus and after chronic estrogen (E2) replacement in ovariectomized (OVX) female rats. However, whether rapid nongenomic effects of estrogen mediate these hemodynamic effects of ethanol remains unanswered. To test this hypothesis, we investigated the effect of ethanol (0.5 or 1.5 g/kg iv) on left ventricular (LV) function and oxidative markers in OVX rats pretreated 30 min earlier with 1 μg/kg E2 (OVXE2) or vehicle (OVX) and in proestrus sham-operated (SO) rats. In SO rats, ethanol caused significant and dose-related reductions in BP, rate of rise in LV pressure (LV dP/dtmax), and LV developed pressure (LVDP). These effects of ethanol disappeared in OVX rats and were restored in OVXE2 rats, suggesting rapid estrogen receptor signaling mediates the detrimental effects of ethanol on LV function. Ex vivo studies revealed that the estrogen-dependent myocardial dysfunction caused by ethanol was coupled with higher LV 1) generation of reactive oxygen species (ROS), 2) expression of malondialdehyde and 4-hydroxynonenal protein adducts, 3) phosphorylation of protein kinase B (Akt) and extracellular signal-regulated kinases (ERK1/2), and 4) catalase activity. ERK1/2 inhibition by PD-98059 (1 mg/kg iv) abrogated the myocardial dysfunction, hypotension, and the elevation in myocardial ROS generation caused by ethanol. We conclude that rapid estrogen receptor signaling is implicated in cellular events that lead to the generation of aldehyde protein adducts and Akt/ERK1/2 phosphorylation, which ultimately mediate the estrogen-dependent LV oxidative stress and dysfunction caused by ethanol in female rats. PMID:24368668

  1. Estrogen and estrogen receptors in cardiovascular oxidative stress.

    PubMed

    Arias-Loza, Paula-Anahi; Muehlfelder, Melanie; Pelzer, Theo

    2013-05-01

    The cardiovascular system of a premenopausal woman is prepared to adapt to the challenges of increased cardiac output and work load that accompany pregnancy. Thus, it is tempting to speculate whether enhanced adaptability of the female cardiovascular system might be advantageous under conditions that promote cardiovascular disease. In support of this concept, 17β-estradiol as the major female sex hormone has been shown to confer protective cardiovascular effects in experimental studies. Mechanistically, these have been partially linked to the prevention and protection against oxidative stress. Current evidence indicates that estrogens attenuate oxidative stress at two levels: first, by preventing generation of reactive oxygen species (ROS) and, second, by scavenging ROS in the myocardium and in the vasculature. The purpose of this review is to give an overview on current concepts on conditions and mechanisms by which estrogens protect the cardiovascular system against ROS-mediated cellular injury.

  2. Removal of arsenic, vanadium and/or nickel compounds from spent catecholated polymer

    DOEpatents

    Fish, R.H.

    1987-04-21

    Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20 to 100 C with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

  3. Removal of arsenic, vanadium and/or nickel compounds from spent catecholated polymer

    DOEpatents

    Fish, Richard H.

    1987-01-01

    Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20.degree. to 100.degree. C. with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

  4. Isozymes of Ipomoea batatas catechol oxidase differ in catalase-like activity.

    PubMed

    Gerdemann, C; Eicken, C; Magrini, A; Meyer, H E; Rompel, A; Spener, F; Krebs, B

    2001-07-01

    The amino acid sequences of two isozymes of catechol oxidase from sweet potatoes (Ipomoea batatas) were determined by Edman degradation of BrCN cleavage fragments of the native protein and by sequencing of amplified cDNA fragments. Sequence alignment and phylogenetic analysis of plant catechol oxidases revealed about 80% equidistance between the two I. batatas catechol oxidases and approximately 40--60% to catechol oxidases of other plants. When H(2)O(2) was applied as substrate the 39 kDa isozyme, but not the 40 kDa isozyme, showed catalase-like activity. The structure of the 40 kDa isozyme was modeled on the basis of the published crystal structure of the 39 kDa isozyme [T. Klabunde et al., Nat. Struct. Biol. 5 (1998) 1084]. The active site model closely resembled that of the 39 kDa isozyme determined by crystallography, except for a mutation of Thr243 (40 kDa isozyme) to Ile241 (39 kDa isozyme) close to the dimetal center. This residue difference affects the orientation of the Glu238/236 residue, which is thought to be responsible for the catalase-like activity of the 39 kDa isozyme for which a catalytic mechanism is proposed. PMID:11451442

  5. Mechanochemical transformation of an organic ligand on mineral surfaces: the efficiency of birnessite in catechol degradation.

    PubMed

    Di Leo, Paola; Pizzigallo, Maria Donata Rosa; Ancona, Valeria; Di Benedetto, Francesco; Mesto, Ernesto; Schingaro, Emanuela; Ventruti, Gennaro

    2012-01-30

    The aim of this work is to investigate the efficiency of the phyllomanganate birnessite in degrading catechol after mechanochemical treatments. A synthesized birnessite and the organic molecule were grounded together in a high energy mill and the xenobiotic-mineral surface reactions induced by the grinding treatment have been investigated by means of X-ray powder diffraction, X-ray fluorescence, thermal analysis and spectroscopic techniques as well as high-performance liquid chromatography and voltammetric techniques. If compared to the simple contact between the birnessite and the organic molecule, mechanochemical treatments have revealed to be highly efficient in degrading catechol molecules, in terms both of time and extent. Due to the two phenolic groups of catechol and the small steric hindrance of the molecule, the extent of the mechanochemically induced degradation of catechol onto birnessite surfaces is quite high. The degradation mechanism mainly occurs via a redox reaction. It implies the formation of a surface bidentate inner-sphere complex between the phenolic group of the organic molecules and the Mn(IV) from the birnessite structure. Structural changes occur on the MnO(6) layers of birnessite as due to the mechanically induced surface reactions: reduction of Mn(IV), consequent formation of Mn(III) and new vacancies, and free Mn(2+) ions production.

  6. Role of catechol structure in the adsorption and transformation reactions of L-DOPA in soils.

    PubMed

    Furubayashi, Akihiro; Hiradate, Syuntaro; Fujii, Yoshiharu

    2007-02-01

    3-(3',4'-Dihydroxyphenyl)-L-alanine (L-DOPA), which is synthesized in velvet bean (Mucuna pruriens), inhibits plant growth. The concentration of L-DOPA in soil is reduced by adsorption and transformation reactions, which can result in the reduction of its plant-growth-inhibitory activity. To determine which part of the L-DOPA structure is involved in the adsorption and soil transformation reactions, we compared the kinetics of L-DOPA disappearance in a volcanic ash soil with that of L-phenylalanine (3-phenyl-L-alanine) and L-tyrosine (3-(4'-hydroxyphenyl)-L-alanine), compounds that are similar in structure to L-DOPA but do not have a catechol (o-dihydroxybenzene) moiety. L-Phenylalanine and L-tyrosine were not adsorbed and transformed in the soil at equilibrium pH values between 4 and 7. These results suggest that the adsorption and transformation reactions of L-DOPA in the soil involve the catechol moiety and not the amino and carboxylic acid groups, which are common to all three compounds. Like L-DOPA, (+)-catechin, another allelochemical that contains a catechol moiety, underwent adsorption and soil transformation reactions. Thus, we concluded that the concentrations of allelochemicals bearing a catechol moiety in soils will decrease rapidly owing to adsorption and transformation reactions, and this decrease will be faster in soils with a high pH value or high adsorption ability. Owing to this decrease in concentration, allelopathic phenomena may not occur.

  7. Mechanisms of product formation from the pyrolytic thermal degradation of catechol.

    PubMed

    Lomnicki, Slawomir; Truong, Hieu; Dellinger, Barry

    2008-09-01

    Catechol has been identified as one of the most abundant organic products in tobacco smoke and a major molecular precursor for semiquinone type radicals in the combustion of biomass material. The high-temperature gas-phase pyrolysis of catechol under hydrogen-rich and hydrogen-lean conditions was studied using a fused-silica tubular flow reactor coupled to an in-line GC/MS analytical system. Thermal degradation of catechol over temperature range of 250-1000 degrees C with a reaction time of 2.0s yielded a variety products including phenol, benzene, dibenzofuran, dibenzo-p-dioxin, phenylethyne, styrene, indene, anthracene, naphthalene, and biphenylene. Ortho-benzoquinone which is typically associated with the presence of semiquinone radicals was not observed and is proposed to be the result of fast decomposition reactions that lead to a variety of other reaction products. This is in contrast to the decomposition of hydroquinone that produced para-benzoquinone as the major product. A detailed mechanism of the degradation pathway of catechol is proposed.

  8. Transformation of phenol, catechol, guaiacol and syringol exposed to sodium hypochlorite.

    PubMed

    Michałowicz, Jaromir; Duda, Wirgiliusz; Stufka-Olczyk, Jadwiga

    2007-01-01

    Germs, xenobiotics and organic matter that influence the colour, turbidity and organoloeptic properties of water are removed by chlorination. Unfortunately, chlorine oxidants including sodium hypochlorite, used in water treatment induce processes that partly convert the treated compounds to unwanted chlorinated derivatives. The purpose of this work was to analyse the efficiency of transformation of phenol, catechol, guaiacol and syringol exposed to sodium hypochlorite and determine the intermediates formed during oxidative conversion of these compounds. The analysis was performed in aerobic conditions, both in acidic (pH 4.0) and alkaline (pH 8.0) medium. The effectiveness of transformation was slightly higher in acidic in comparison to alkaline conditions. Some chlorophenols, such as 2-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol were determined as the products of phenol conversion. Chlorophenols were also formed during catechol, guaiacol and syringol transformation by replacement of hydroxy and methoxy residues by chlorine atoms. Moreover, some chlorocatechols and chlorinated methoxyphenols were determined during catechol and methoxyphenols transformations. Higher concentrations of chlorinated compounds were observed in the alkaline environment during phenol transformation. Conversion of catechol and methoxyphenols generated higher amounts of chlorinated intermediates in the acidic medium. In samples carboxylic acids like acetic and formic acids were determined. The formation of these compounds was the result of the cleavage of aromatic structure of phenols.

  9. Organic impurity profiling of 3,4-methylenedioxymethamphetamine (MDMA) synthesised from catechol.

    PubMed

    Heather, Erin; Shimmon, Ronald; McDonagh, Andrew M

    2015-03-01

    This work examines the organic impurity profile of 3,4-methylenedioxymethamphetamine (MDMA) that has been synthesised from catechol (1,2-dihydroxybenzene), a common chemical reagent available in industrial quantities. The synthesis of MDMA from catechol proceeded via the common MDMA precursor safrole. Methylenation of catechol yielded 1,3-benzodioxole, which was brominated and then reacted with magnesium allyl bromide to form safrole. Eight organic impurities were identified in the synthetic safrole. Safrole was then converted to 3,4-methylenedioxyphenyl-2-propanone (MDP2P) using two synthetic methods: Wacker oxidation (Route 1) and an isomerisation/peracid oxidation/acid dehydration method (Route 2). MDMA was then synthesised by reductive amination of MDP2P. Thirteen organic impurities were identified in MDMA synthesised via Route 1 and eleven organic impurities were identified in MDMA synthesised via Route 2. Overall, organic impurities in MDMA prepared from catechol indicated that synthetic safrole was used in the synthesis. The impurities also indicated which of the two synthetic routes was utilised.

  10. Degradation of catechol by ionizing radiation, ozone and the combined process ozone-electron-beam

    NASA Astrophysics Data System (ADS)

    Kubesch, K.; Zona, R.; Solar, S.; Gehringer, P.

    2005-03-01

    The influence of oxygen on the radiation-induced degradation of catechol (5×10 -4 mol dm -3, 55 mg dm -3) in distilled water was studied by gamma-radiolysis in the presence of air (A) and using air saturation (AS) during irradiation. Under AS conditions a complete decomposition of catechol as well as of the trihydroxybenzene products was obtained by a dose of 6 kGy, without air saturation all phenolic compounds were still present at 10 kGy. Using AS, at 12 kGy the total organic carbon (TOC) was reduced by 63%, without air saturation by 17.5%. Detoxification was only obtained in AS solutions. In the presence of the natural matrix of the local tap water no trihydroxybenzene products were formed and for total decomposition of catechol in AS solutions 9 kGy were required. The comparison of the effectiveness of an electron beam (EB), an ozone (O 3) and a combined EB/O 3 process showed, that by EB/O 3 the extent of catechol degradation corresponded to the sum of the decay with EB and with ozone, whereas for the chemical oxygen demand and TOC reduction a synergistic effect was evident.

  11. Isozymes of Ipomoea batatas catechol oxidase differ in catalase-like activity.

    PubMed

    Gerdemann, C; Eicken, C; Magrini, A; Meyer, H E; Rompel, A; Spener, F; Krebs, B

    2001-07-01

    The amino acid sequences of two isozymes of catechol oxidase from sweet potatoes (Ipomoea batatas) were determined by Edman degradation of BrCN cleavage fragments of the native protein and by sequencing of amplified cDNA fragments. Sequence alignment and phylogenetic analysis of plant catechol oxidases revealed about 80% equidistance between the two I. batatas catechol oxidases and approximately 40--60% to catechol oxidases of other plants. When H(2)O(2) was applied as substrate the 39 kDa isozyme, but not the 40 kDa isozyme, showed catalase-like activity. The structure of the 40 kDa isozyme was modeled on the basis of the published crystal structure of the 39 kDa isozyme [T. Klabunde et al., Nat. Struct. Biol. 5 (1998) 1084]. The active site model closely resembled that of the 39 kDa isozyme determined by crystallography, except for a mutation of Thr243 (40 kDa isozyme) to Ile241 (39 kDa isozyme) close to the dimetal center. This residue difference affects the orientation of the Glu238/236 residue, which is thought to be responsible for the catalase-like activity of the 39 kDa isozyme for which a catalytic mechanism is proposed.

  12. Development of an iron(II)-catalyzed aerobic catechol cleavage and biomimetic synthesis of betanidin.

    PubMed

    Guimond, Nicolas; Mayer, Peter; Trauner, Dirk

    2014-07-28

    An aerobic iron(II)-catalyzed cleavage of catechols was developed. This reaction allows for the preparation of 2-methoxy-2 H-pyrans that can be employed as versatile building blocks for synthesis. The utility of this biomimetic oxidative cleavage is featured in the synthesis of betanidin, a natural colorant with antioxidant properties.

  13. Association of Catechol-O-Methyltransferase (COMT) Polymorphism and Academic Achievement in a Chinese Cohort

    ERIC Educational Resources Information Center

    Yeh, Ting-Kuang; Chang, Chun-Yen; Hu, Chung-Yi; Yeh, Ting-Chi; Lin, Ming-Yeh

    2009-01-01

    Catechol-O-methyltransferase (COMT) is a methylation enzyme that catalyzes the degradation pathway and inactivation of dopamine. It is accepted widely as being involved in the modulation of dopaminergic physiology and prefrontal cortex (PFC) function. The COMT Val158Met polymorphism is associated with variation in COMT activity. COMT 158Met allele…

  14. Revealing the role of catechol moieties in the interactions between peptides and inorganic surfaces.

    PubMed

    Das, Priyadip; Reches, Meital

    2016-08-18

    Catechol (1,2-dihydroxy benzene) moieties are being widely used today in new adhesive technologies. Understanding their mechanism of action is therefore of high importance for developing their applications in materials science. This paper describes a single-molecule study of the interactions between catechol-related amino acid residues and a well-defined titanium dioxide (TiO2) surface. It is the first quantified measurement of the adhesion of these residues with a well-defined TiO2 surface. Single-molecule force spectroscopy measurements with AFM determined the role of different substitutions of the catechol moiety on the aromatic ring in the adhesion to the surface. These results shed light on the nature of interactions between these residues and inorganic metal oxide surfaces. This information is important for the design and fabrication of catechol-based materials such as hydrogels, coatings, and composites. Specifically, the interaction with TiO2 is important for the development of solar cells. PMID:27503417

  15. Catechol-O-methyltransferase: a method for autoradiographic visualization of isozymes in cellogel

    SciTech Connect

    Brahe, C.; Crosti, N.; Meera Khan, P.; Serra, A.

    1984-02-01

    An electrophoretic procedure for separating the molecular forms of catechol-O-methyltransferase in cellulose acetate gel is described; the zones of enzyme activity were revealed by autoradiography. The electrophoretic patterns of the enzyme in several tissues and cell lines derived from four different species are presented.

  16. Glucosylation of Catechol with the GTFA Glucansucrase Enzyme from Lactobacillus reuteri and Sucrose as Donor Substrate.

    PubMed

    te Poele, Evelien M; Grijpstra, Pieter; van Leeuwen, Sander S; Dijkhuizen, Lubbert

    2016-04-20

    Lactic acid bacteria use glucansucrase enzymes for synthesis of gluco-oligosaccharides and polysaccharides (α-glucans) from sucrose. Depending on the glucansucrase enzyme, specific α-glucosidic linkages are introduced. GTFA-ΔN (N-terminally truncated glucosyltransferase A) is a glucansucrase enzyme of Lactobacillus reuteri 121 that synthesizes the reuteran polysaccharide with (α1 → 4) and (α1 → 6) glycosidic linkages. Glucansucrases also catalyze glucosylation of various alternative acceptor substrates. At present it is unclear whether the linkage specificity of these enzymes is the same in oligo/polysaccharide synthesis and in glucosylation of alternative acceptor substrates. Our results show that GTFA-ΔN glucosylates catechol into products with up to at least 5 glucosyl units attached. These catechol glucosides were isolated and structurally characterized using 1D/2D (1)H NMR spectroscopy. They contained 1 to 5 glucose units with different (α1 → 4) and (α1 → 6) glycosidic linkage combinations. Interestingly, a branched catechol glucoside was also formed along with a catechol glucoside with 2 successive (α1 → 6) glycosidic linkages, products that are absent when only sucrose is used as both glycosyl donor and acceptor substrate. PMID:26898769

  17. Estrogen receptors in the wobbler mouse.

    PubMed

    Siegel, L I; Fox, T O

    1985-12-01

    Recent research has raised the interesting possibility that the neurological mutant mouse, wobbler (wr/wr), possesses an estrogen receptor deficit analogous to the androgen receptor deficiency found in androgen-resistant mice with testicular feminization. In the present report we examined estrogen-binding activity in cytosolic extracts of kidney, liver, and brain from wobbler mice, littermate control animals, and C57BL/6J mice, using DNA-cellulose chromatography. Estrogen binding components exhibiting properties of estrogen receptors were present in all tissues examined. Estrogen receptors adhered to DNA, displayed characteristic elution profiles from DNA-cellulose, and showed high affinity and limited capacity for estradiol, in contrast to non-receptor entities which bind estradiol. The qualitative elution patterns for estrogen receptors did not differ among groups within each tissue studied, and were similar to those reported previously in mouse kidney and brain. While estrogen receptors have been shown in mouse liver by other techniques, this is the first demonstration of putative estrogen receptors in mouse liver by DNA-cellulose chromatography. No consistent deficits in estrogen receptor concentration were found in wobblers compared to littermates. Thus, the data do not support the hypothesis that the wobbler mouse is an estrogen receptor-deficient mutant.

  18. Chemistry and Biology of Aflatoxin-DNA Adducts

    SciTech Connect

    Stone, Michael P.; Banerjee, Surajit; Brown, Kyle L.; Egli, Martin

    2012-03-27

    Aspergillus flavus is a fungal contaminant of stored rice, wheat, corn, and other grainstuffs, and peanuts. This is of concern to human health because it produces the mycotoxin aflatoxin B{sub 1} (AFB{sub 1}), which is genotoxic and is implicated in the etiology of liver cancer. AFB{sub 1} is oxidized in vivo by cytochrome P450 to form aflatoxin B{sub 1} epoxide, which forms an N7-dG adduct (AFB{sub 1}-N7-dG) in DNA. The latter rearranges to a formamidopyrimidine (AFB{sub 1}-FAPY) derivative that equilibrates between {alpha} and {beta} anomers of the deoxyribose. In DNA, both the AFB{sub 1}-N7-dG and AFB{sub 1}-{beta}-FAPY adducts intercalate above the 5'-face of the damaged guanine. Each produces G {yields} T transversions in Escherichia coli, but the AFB{sub 1}-{beta}-FAPY adduct is more mutagenic. The Sulfolobus solfataricus P2 DNA polymerase IV (Dpo4) provides a model for understanding error-prone bypass of the AFB{sub 1}-N7-dG and AFB{sub 1}-{beta}-FAPY adducts. It bypasses the AFB{sub 1}-N7-dG adduct, but it conducts error-prone replication past the AFB{sub 1}-FAPY adduct, including mis-insertion of dATP, consistent with the G {yields} T mutations characteristic of AFB{sub 1} mutagenesis in E. coli. Crystallographic analyses of a series of binary and ternary complexes with the Dpo4 polymerase revealed differing orientations of the N7-C8 bond of the AFB{sub 1}-N7-dG adduct as compared to the N{sup 5}-C8 bond in the AFB{sub 1}-{beta}-FAPY adduct, and differential accommodation of the intercalated AFB{sub 1} moieties within the active site. These may modulate AFB{sub 1} lesion bypass by this polymerase.

  19. Quantitation of DNA Adducts Induced by 1,3-Butadiene

    NASA Astrophysics Data System (ADS)

    Sangaraju, Dewakar; Villalta, Peter W.; Wickramaratne, Susith; Swenberg, James; Tretyakova, Natalia

    2014-07-01

    Human exposure to 1,3-butadiene (BD) present in automobile exhaust, cigarette smoke, and forest fires is of great concern because of its potent carcinogenicity. The adverse health effects of BD are mediated by its epoxide metabolites such as 3,4-epoxy-1-butene (EB), which covalently modify genomic DNA to form promutagenic nucleobase adducts. Because of their direct role in cancer, BD-DNA adducts can be used as mechanism-based biomarkers of BD exposure. In the present work, a mass spectrometry-based methodology was developed for accurate, sensitive, and precise quantification of EB-induced N-7-(1-hydroxy-3-buten-2-yl) guanine (EB-GII) DNA adducts in vivo. In our approach, EB-GII adducts are selectively released from DNA backbone by neutral thermal hydrolysis, followed by ultrafiltration, offline HPLC purification, and isotope dilution nanoLC/ESI+-HRMS3 analysis on an Orbitrap Velos mass spectrometer. Following method validation, EB-GII lesions were quantified in human fibrosarcoma (HT1080) cells treated with micromolar concentrations of EB and in liver tissues of rats exposed to sub-ppm concentrations of BD (0.5-1.5 ppm). EB-GII concentrations increased linearly from 1.15 ± 0.23 to 10.11 ± 0.45 adducts per 106 nucleotides in HT1080 cells treated with 0.5-10 μM DEB. EB-GII concentrations in DNA of laboratory rats exposed to 0.5, 1.0, and 1.5 ppm BD were 0.17 ± 0.05, 0.33 ± 0.08, and 0.50 ± 0.04 adducts per 106 nucleotides, respectively. We also used the new method to determine the in vivo half-life of EB-GII adducts in rat liver DNA (2.20 ± 0.12 d) and to detect EB-GII in human blood DNA. To our knowledge, this is the first application of nanoLC/ESI+-HRMS3 Orbitrap methodology to quantitative analysis of DNA adducts in vivo.

  20. Recognition of platinum-DNA adducts by HMGB1a.

    PubMed

    Ramachandran, Srinivas; Temple, Brenda; Alexandrova, Anastassia N; Chaney, Stephen G; Dokholyan, Nikolay V

    2012-09-25

    Cisplatin (CP) and oxaliplatin (OX), platinum-based drugs used widely in chemotherapy, form adducts on intrastrand guanines (5'GG) in genomic DNA. DNA damage recognition proteins, transcription factors, mismatch repair proteins, and DNA polymerases discriminate between CP- and OX-GG DNA adducts, which could partly account for differences in the efficacy, toxicity, and mutagenicity of CP and OX. In addition, differential recognition of CP- and OX-GG adducts is highly dependent on the sequence context of the Pt-GG adduct. In particular, DNA binding protein domain HMGB1a binds to CP-GG DNA adducts with up to 53-fold greater affinity than to OX-GG adducts in the TGGA sequence context but shows much smaller differences in binding in the AGGC or TGGT sequence contexts. Here, simulations of the HMGB1a-Pt-DNA complex in the three sequence contexts revealed a higher number of interface contacts for the CP-DNA complex in the TGGA sequence context than in the OX-DNA complex. However, the number of interface contacts was similar in the TGGT and AGGC sequence contexts. The higher number of interface contacts in the CP-TGGA sequence context corresponded to a larger roll of the Pt-GG base pair step. Furthermore, geometric analysis of stacking of phenylalanine 37 in HMGB1a (Phe37) with the platinated guanines revealed more favorable stacking modes correlated with a larger roll of the Pt-GG base pair step in the TGGA sequence context. These data are consistent with our previous molecular dynamics simulations showing that the CP-TGGA complex was able to sample larger roll angles than the OX-TGGA complex or either CP- or OX-DNA complexes in the AGGC or TGGT sequences. We infer that the high binding affinity of HMGB1a for CP-TGGA is due to the greater flexibility of CP-TGGA compared to OX-TGGA and other Pt-DNA adducts. This increased flexibility is reflected in the ability of CP-TGGA to sample larger roll angles, which allows for a higher number of interface contacts between the Pt

  1. Targeted Radiotherapy of Estrogen Receptor Positive Tumors

    SciTech Connect

    Raghavan Rajagopalan

    2006-08-31

    The overall objectives of the proposal were to develop estrogen receptor (ER) binding small molecule radiopharmaceuticals for targeted radiotherapy of ER positive (ER+) tumors. In particular, this proposal focused on embedding a {sup 186,188}Re or a {sup 32}P radionuclide into an estrogen steroidal framework by isosteric substitution such that the resulting structure is topologically similar to the estrogen (estrogen mimic). The estrogen mimic molecules expected to bind to the ER and exhibit biodistribution akin to that of native estrogen due to structural mimicry. It is anticipated that the {sup 186,188}Re- or a {sup 32}P-containing estrogen mimics will be useful for targeted molecular radiotherapy of ER+ tumors. It is well established that the in vivo target tissue uptake of estrogen like steroidal molecules is related to the binding of the steroids to sex hormone binding globulin (SHBG). SHBG is important in the uptake of estrogens and testosterone in target tissues by SHBG receptors on the cell surface. However, hitherto the design of estrogen like small molecule radiopharmaceuticals was focused on optimizing ER binding characteristics without emphasis on SHBG binding properties. Consequently, even the molecules with good ER affinity in vitro, performed poorly in biodistribution studies. Based on molecular modeling studies the proposal focused on developing estrogen mimics 1-3 which were topologically similar to native estrogens, and form hydrogen bonds in ER and SHBG in the same manner as those of native estrogens. To this end the technical objectives of the proposal focused on synthesizing the rhenium-estrone and estradiol mimics 1 and 2 respectively, and phosphorous estradiol mimic 3 and to assess their stability and in vitro binding characteristics to ER and SHBG.

  2. Polyaniline-iron oxide nanohybrid film as multi-functional label-free electrochemical and biomagnetic sensor for catechol.

    PubMed

    Chandra, Sudeshna; Lang, Heinrich; Bahadur, Dhirendra

    2013-09-17

    Polyaniline-iron oxide magnetic nanohybrid was synthesized and characterized using various spectroscopic, microstructural and electrochemical techniques. The smart integration of Fe3O4 nanoparticles within the polyaniline (PANI) matrix yielded a mesoporous nanohybrid (Fe3O4@PANI) with high surface area (94 m(2) g(-1)) and average pore width of 12.8 nm. Catechol is quasi-reversibly oxidized to o-quinone and reduced at the Fe3O4@PANI modified electrodes. The amperometric current response toward catechol was evaluated using the nanohybrid and the sensitivity and detection limit were found to be 312 μA μL(-1) and 0.2 nM, respectively. The results from electrochemical impedance spectroscopy (EIS) indicated that the increased solution resistance (Rs) was due to elevated adsorption of catechol on the modified electrodes. Photoluminescence spectra showed ligand-to-metal charge transfer (LMCT) between p-π orbitals of the phenolate oxygen in catechol and the d-σ* metal orbital of Fe3O4@PANI nanohybrid. Potential dependent spectroelectrochemical behavior of Fe3O4@PANI nanohybrid toward catechol was studied using UV/vis/NIR spectroscopy. The binding activity of the biomagnetic particles to catechol through Brownian relaxation was evident from AC susceptibility measurements. The proposed sensor was used for successful recovery of catechol in tap water samples.

  3. N-Heterocyclic carbene phosphaketene adducts as precursors to carbene-phosphinidene adducts and a rearranged π-system.

    PubMed

    Li, Zhongshu; Chen, Xiaodan; Li, Yaqi; Su, Cheng-Yong; Grützmacher, Hansjörg

    2016-10-15

    The nucleophilic attack of NHCs on the electron deficient carbon of tetryl substituted phosphaketenes Ph3E-P[double bond, length as m-dash]C[double bond, length as m-dash]O (E = Sn-Si), leads quantitatively to the formation of NHC-phosphaketene adducts. With E = Sn or Ge, these zwitterionic adducts decompose upon thermolysis under the release of carbon monoxide to give zwitterionic NHC-phosphinidene adducts. With E = Si an OCP to CPO rearrangement occurs which leads to the formation of a linear π-conjugated molecule, NHC[double bond, length as m-dash]C[double bond, length as m-dash]P-O-SiPh3. PMID:27545980

  4. Growth of Actinobacillus pleuropneumoniae is promoted by exogenous hydroxamate and catechol siderophores.

    PubMed Central

    Diarra, M S; Dolence, J A; Dolence, E K; Darwish, I; Miller, M J; Malouin, F; Jacques, M

    1996-01-01

    Siderophores bind ferric ions and are involved in receptor-specific iron transport into bacteria. Six types of siderophores were tested against strains representing the 12 different serotypes of Actinobacillus pleuropneumoniae. Ferrichrome and bis-catechol-based siderophores showed strong growth-promoting activities for A. pleuropneumoniae in a disk diffusion assay. Most strains of A. pleuropneumoniae tested were able to use ferrichrome (21 of 22 or 95%), ferrichrome A (20 of 22 or 90%), and lysine-based bis-catechol (20 of 22 or 90%), while growth of 36% (8 of 22) was promoted by a synthetic hydroxamate, N5-acetyl-N5-hydroxy-L-ornithine tripeptide. A. pleuropneumoniae serotype 1 (strain FMV 87-682) and serotype 5 (strain 2245) exhibited a distinct yellow halo around colonies on Chrome Azurol S agar plates, suggesting that both strains can produce an iron chelator (siderophore) in response to iron stress. The siderophore was found to be neither a phenolate nor a hydroxamate by the chemical tests of Arnow and Csaky, respectively. This is the first report demonstrating the production of an iron chelator and the use of exogenous siderophores by A. pleuropneumoniae. A spermidine-based bis-catechol siderophore conjugated to a carbacephalosporin was shown to inhibit growth of A. pleuropneumoniae. A siderophore-antibiotic-resistant strain was isolated and shown to have lost the ability to use ferrichrome, synthetic hydroxamate, or catechol-based siderophores when grown under conditions of iron restriction. This observation indicated that a common iron uptake pathway, or a common intermediate, for hydroxamate- and catechol-based siderophores may exist in A. pleuropneumoniae. PMID:8975614

  5. Catechol oxidation by ozone and hydroxyl radicals at the air-water interface.

    PubMed

    Pillar, Elizabeth A; Camm, Robert C; Guzman, Marcelo I

    2014-12-16

    Anthropogenic emissions of aromatic hydrocarbons promptly react with hydroxyl radicals undergoing oxidation to form phenols and polyphenols (e.g., catechol) typically identified in the complex mixture of humic-like substances (HULIS). Because further processing of polyphenols in secondary organic aerosols (SOA) can continue mediated by a mechanism of ozonolysis at interfaces, a better understanding about how these reactions proceed at the air-water interface is needed. This work shows how catechol, a molecular probe of the oxygenated aromatic hydrocarbons present in SOA, can contribute interfacial reactive species that enhance the production of HULIS under atmospheric conditions. Reactive semiquinone radicals are quickly produced upon the encounter of 40 ppbv-6.0 ppmv O3(g) with microdroplets containing [catechol] = 1-150 μM. While the previous pathway results in the instantaneous formation of mono- and polyhydroxylated aromatic rings (PHA) and chromophoric mono- and polyhydroxylated quinones (PHQ), a different channel produces oxo- and dicarboxylic acids of low molecular weight (LMW). The cleavage of catechol occurs at the 1,2 carbon-carbon bond at the air-water interface through the formation of (1) an ozonide intermediate, (2) a hydroperoxide, and (3) cis,cis-muconic acid. However, variable [catechol] and [O3(g)] can affect the ratio of the primary products (cis,cis-muconic acid and trihydroxybenzenes) and higher order products observed (PHA, PHQ, and LMW oxo- and dicarboxylic acids). Secondary processing is confirmed by mass spectrometry, showing the production of crotonic, maleinaldehydic, maleic, glyoxylic, and oxalic acids. The proposed pathway can contribute precursors to aqueous SOA (AqSOA) formation, converting aromatic hydrocarbons into polyfunctional species widely found in tropospheric aerosols with light-absorbing brown carbon.

  6. Effects of Metal Oxides on a Fungal Laccase Activity and Catechol Transformation

    NASA Astrophysics Data System (ADS)

    Ahn, M.; Dec, J.; Bollag, J.

    2003-12-01

    The transformation of naturally occurring phenols to humic polymers is generally catalyzed by various phenoloxidases commonly present in soil. Some poorly crystalline metal oxides and hydroxides may also participate in these reactions. In this study, catechol (0.1 M) was incubated with a fungal laccase (950 unit/mL) in the presence of poorly crystalline minerals (ferrihydrite; 50 mg/mL: birnessite; 1 mg/mL: aluminum hydroxide; 50 mg/mL) to examine the interaction between these soil components under field conditions. Birnessite had an inhibitory effect on the laccase-mediated transformation of catechol (by up to 40%). Enzyme inhibition was possibly caused by the rapid production of humic-like polymers by birnessite. An additional inhibitory effect was caused by Manganese ion released from birnessite as it oxidized catechol (up to 70% loss in enzyme activity). In contrast to birnessite, aluminum hydroxide had an additive effect on the disappearance of catechol despite the rapid adsorption of the enzyme by this mineral (Xm=6.18μ g/mg). Apparently, the adsorbed laccase retained some enzyme activity. Ferrihydrite also had an additive effect on catechol transformation. However, as compared to aluminum hydroxide, ferrihydrite adsorbed less laccase (Xm=0.89μ g/mg) and more humic-like polymers. Unlike birnessite, aluminum hydroxide and ferrihydrite released negligible amounts of metal ions. In conclusion, under field conditions, phenoloxidase activity may be diminished by the presence of birnessite, but the presence of either ferrihydrite or aluminum hydroxide is less likely to inhibit enzyme activity, and may even enhance substrate transformation.

  7. Condensed-phase versus gas-phase ozonolysis of catechol: A combined experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    Barnum, Timothy J.; Medeiros, Nicholas; Hinrichs, Ryan Z.

    2012-08-01

    Anthropogenic emissions of volatile aromatic compounds contribute to the formation of secondary organic aerosols (SOA), especially in urban environments. Aromatic SOA precursors typically require oxidation by hydroxyl radicals, although recent work suggests that ozonolysis of 1,2-benzenediols produces SOA in high yields. We employed attenuated total reflectance and transmission infrared spectroscopy to investigate the heterogeneous ozonolysis of catechol thin films. Formation of the dominant condensed-phase product muconic acid was highly dependent on relative humidity (RH) with few products detected below 40% RH and a maximum reactive uptake coefficient of γ = (5.6 ± 0.5) × 10-5 measured at 81.2% RH. We also performed quantum chemical calculations mapping out several reaction pathways for the homogeneous ozonolysis of gaseous catechol. 1,3-cycloaddition transition states were rate limiting with the most favorable activation energies at 45.4 and 47.1 kJ mol-1 [CCSD(T)/6-311++G(d,p)] corresponding to addition across and adjacent to the diol Cdbnd C, respectively. Gas-phase rate constants, calculated using transition state theory, were six orders of magnitude slower than experimental values. In contrast, a calculated activation energy was lower for the ozonolysis of a catechol•H2O complex, which serves as a first-approximation for modeling the ozonolysis of condensed-phase catechol. These combined results suggests that homogeneous ozonolysis of catechol may not be important for the formation of secondary organic aerosols but that ozonolysis of surface-adsorbed catechol may contribute to SOA growth.

  8. Catechol oxidation by ozone and hydroxyl radicals at the air-water interface.

    PubMed

    Pillar, Elizabeth A; Camm, Robert C; Guzman, Marcelo I

    2014-12-16

    Anthropogenic emissions of aromatic hydrocarbons promptly react with hydroxyl radicals undergoing oxidation to form phenols and polyphenols (e.g., catechol) typically identified in the complex mixture of humic-like substances (HULIS). Because further processing of polyphenols in secondary organic aerosols (SOA) can continue mediated by a mechanism of ozonolysis at interfaces, a better understanding about how these reactions proceed at the air-water interface is needed. This work shows how catechol, a molecular probe of the oxygenated aromatic hydrocarbons present in SOA, can contribute interfacial reactive species that enhance the production of HULIS under atmospheric conditions. Reactive semiquinone radicals are quickly produced upon the encounter of 40 ppbv-6.0 ppmv O3(g) with microdroplets containing [catechol] = 1-150 μM. While the previous pathway results in the instantaneous formation of mono- and polyhydroxylated aromatic rings (PHA) and chromophoric mono- and polyhydroxylated quinones (PHQ), a different channel produces oxo- and dicarboxylic acids of low molecular weight (LMW). The cleavage of catechol occurs at the 1,2 carbon-carbon bond at the air-water interface through the formation of (1) an ozonide intermediate, (2) a hydroperoxide, and (3) cis,cis-muconic acid. However, variable [catechol] and [O3(g)] can affect the ratio of the primary products (cis,cis-muconic acid and trihydroxybenzenes) and higher order products observed (PHA, PHQ, and LMW oxo- and dicarboxylic acids). Secondary processing is confirmed by mass spectrometry, showing the production of crotonic, maleinaldehydic, maleic, glyoxylic, and oxalic acids. The proposed pathway can contribute precursors to aqueous SOA (AqSOA) formation, converting aromatic hydrocarbons into polyfunctional species widely found in tropospheric aerosols with light-absorbing brown carbon. PMID:25423038

  9. The Estrogen Hypothesis of Obesity

    PubMed Central

    Grantham, James P.; Henneberg, Maciej

    2014-01-01

    The explanation of obesity as a simple result of positive energy balance fails to account for the scope of variable responses to diets and lifestyles. It is postulated that individual physiological and anatomical variation may be responsible for developing obesity. Girls in poor families develop greater adiposity than their male siblings, a trend not present in richer environments. This indicates strong influence of estrogen on fat accumulation irrespective of poor socioeconomic conditions. Obesity rates in males and females of developed nations are similar, while in poorer nations obesity is much more prevalent in females. Female to male ratio of obesity correlates inversely with gross domestic product. Therefore, the parity of male and female obesity in developed countries may result from male exposure to environmental estrogen-like substances associated with affluence. These hormonally driven mechanisms may be equally active within both sexes in more developed areas, thereby increasing overall obesity. PMID:24915457

  10. Estrogen turns down "the AIRE".

    PubMed

    Bakhru, Pearl; Su, Maureen A

    2016-04-01

    Genetic alterations are known drivers of autoimmune disease; however, there is a much higher incidence of autoimmunity in women, implicating sex-specific factors in disease development. The autoimmune regulator (AIRE) gene contributes to the maintenance of central tolerance, and complete loss of AIRE function results in the development of autoimmune polyendocrinopathy syndrome type 1. In this issue of the JCI, Dragin and colleagues demonstrate that AIRE expression is downregulated in females as the result of estrogen-mediated alterations at the AIRE promoter. The association between estrogen and reduction of AIRE may at least partially account for the elevated incidence of autoimmune disease in women and has potential implications for sex hormone therapy.

  11. Strategy for identifying unknown hemoglobin adducts using adductome LC-MS/MS data: Identification of adducts corresponding to acrylic acid, glyoxal, methylglyoxal, and 1-octen-3-one.

    PubMed

    Carlsson, Henrik; Törnqvist, Margareta

    2016-06-01

    Electrophilic compounds have the ability to form adducts with nucleophilic sites in proteins and DNA in tissues, and thereby constitute risks for toxic effects. Adductomic approaches are developed for systematic screening of adducts to DNA and blood proteins, with the aim to detect unknown internal exposures to electrophiles. In a previous adductomic screening of adducts to N-terminals in hemoglobin, using LC-MS/MS, 19 unknown adducts were detected in addition to seven previously identified adducts. The present paper describes the identification of four of these unknown adducts, as well as the strategy used to identify them. Using LC-MS data from the screening, hypotheses about adduct identities were formulated: probable precursor electrophiles with matching molecular weights were suggested based on the molecular weights of the modifications and the retention times of the analytes, in combination with comparisons of theoretical Log P calculations and databases. Reference adducts were generated by incubation of blood samples with the hypothesized precursor electrophiles. The four identified precursor electrophiles, corresponding to the observed unknown adducts, were glyoxal, methylglyoxal, acrylic acid and 1-octen-3-one. Possible origins/exposure sources and toxicological information concerning the electrophilic precursors are discussed. The identified adducts could be explored as possible biomarkers for exposure. PMID:27046699

  12. ANALYSIS OF LAGOON SAMPLES FROM DIFFERENT CONCENTRATED ANIMAL FEEDING OPERATIONS FOR ESTROGENS AND ESTROGEN CONJUGATES

    EPA Science Inventory

    Although Concentrated Animal Feeding Operations CAFOs) have been identified as potentially important sources for the release of estrogens into the environment, information is lacking on the concentrations of estrogens in whole lagoon effluents (including suspended solids)which ar...

  13. UNUSUALLY STABLE ADDUCT BETWEEN METHANOLYZED AMOXICILLIN OR AMPICILLIN AND THEIR DIKETOPIPERAZINE DERIVATIVES.

    PubMed

    Kosińska, Katarzyna; Frański, Rafał; Frańska, Magdalena

    2016-01-01

    Amoxicillin and ampicillin were subjected to methanolysis. As expected, the methanolysis products were observed by HPLC-ESI-MS. Besides these products, diketopiperazine derivatives were also detected. Additionally, unusually stable adduct formed between the products of methanolysis and diketopiperazine derivatives was also identified. Analogical adducts were detected when ethanolysis was performed instead of methanolysis. HPLC-ESI-MS analysis of the separated adducts confirmed that the adducts were composed of methanolysis products and diketopiperazine derivatives. PMID:27180422

  14. UNUSUALLY STABLE ADDUCT BETWEEN METHANOLYZED AMOXICILLIN OR AMPICILLIN AND THEIR DIKETOPIPERAZINE DERIVATIVES.

    PubMed

    Kosińska, Katarzyna; Frański, Rafał; Frańska, Magdalena

    2016-01-01

    Amoxicillin and ampicillin were subjected to methanolysis. As expected, the methanolysis products were observed by HPLC-ESI-MS. Besides these products, diketopiperazine derivatives were also detected. Additionally, unusually stable adduct formed between the products of methanolysis and diketopiperazine derivatives was also identified. Analogical adducts were detected when ethanolysis was performed instead of methanolysis. HPLC-ESI-MS analysis of the separated adducts confirmed that the adducts were composed of methanolysis products and diketopiperazine derivatives.

  15. Nongenomic Signaling Pathways of Estrogen Toxicity

    PubMed Central

    Watson, Cheryl S.; Jeng, Yow-Jiun; Kochukov, Mikhail Y.

    2010-01-01

    Xenoestrogens can affect the healthy functioning of a variety of tissues by acting as potent estrogens via nongenomic signaling pathways or by interfering with those actions of multiple physiological estrogens. Collectively, our and other studies have compared a wide range of estrogenic compounds, including some closely structurally related subgroups. The estrogens that have been studied include environmental contaminants of different subclasses, dietary estrogens, and several prominent physiological metabolites. By comparing the nongenomic signaling and functional responses to these compounds, we have begun to address the structural requirements for their actions through membrane estrogen receptors in the pituitary, in comparison to other tissues, and to gain insights into their typical non-monotonic dose-response behavior. Their multiple inputs into cellular signaling begin processes that eventually integrate at the level of mitogen-activated protein kinase activities to coordinately regulate broad cellular destinies, such as proliferation, apoptosis, or differentiation. PMID:19955490

  16. Effects of Active-Site Modification and Quaternary Structure on the Regioselectivity of Catechol-O-Methyltransferase.

    PubMed

    Law, Brian J C; Bennett, Matthew R; Thompson, Mark L; Levy, Colin; Shepherd, Sarah A; Leys, David; Micklefield, Jason

    2016-02-18

    Catechol-O-methyltransferase (COMT), an important therapeutic target in the treatment of Parkinson's disease, is also being developed for biocatalytic processes, including vanillin production, although lack of regioselectivity has precluded its more widespread application. By using structural and mechanistic information, regiocomplementary COMT variants were engineered that deliver either meta- or para-methylated catechols. X-ray crystallography further revealed how the active-site residues and quaternary structure govern regioselectivity. Finally, analogues of AdoMet are accepted by the regiocomplementary COMT mutants and can be used to prepare alkylated catechols, including ethyl vanillin. PMID:26797714

  17. Reactivity and selectivity differences between catecholate and catechothiolate Ru complexes. Implications regarding design of stereoselective olefin metathesis catalysts.

    PubMed

    Khan, R Kashif M; Torker, Sebastian; Hoveyda, Amir H

    2014-10-15

    The origins of the unexpected finding that Ru catechothiolate complexes, in contrast to catecholate derivatives, promote exceptional Z-selective olefin metathesis reactions are elucidated. We show that species containing a catechothiolate ligand, unlike catecholates, preserve their structural integrity under commonly used reaction conditions. DFT calculations indicate that, whereas alkene coordination is the stereochemistry-determining step with catecholate complexes, it is through the metallacyclobutane formation that the identity of the major isomer is determined with catechothiolate systems. The present findings suggest that previous models for Z selectivity, largely based on steric differences, should be altered to incorporate electronic factors as well. PMID:25268949

  18. Reactivity and selectivity differences between catecholate and catechothiolate Ru complexes. Implications regarding design of stereoselective olefin metathesis catalysts.

    PubMed

    Khan, R Kashif M; Torker, Sebastian; Hoveyda, Amir H

    2014-10-15

    The origins of the unexpected finding that Ru catechothiolate complexes, in contrast to catecholate derivatives, promote exceptional Z-selective olefin metathesis reactions are elucidated. We show that species containing a catechothiolate ligand, unlike catecholates, preserve their structural integrity under commonly used reaction conditions. DFT calculations indicate that, whereas alkene coordination is the stereochemistry-determining step with catecholate complexes, it is through the metallacyclobutane formation that the identity of the major isomer is determined with catechothiolate systems. The present findings suggest that previous models for Z selectivity, largely based on steric differences, should be altered to incorporate electronic factors as well.

  19. Distinct Effects of Estrogen on Mouse Maternal Behavior: The Contribution of Estrogen Synthesis in the Brain.

    PubMed

    Murakami, Gen

    2016-01-01

    Estrogen surge following progesterone withdrawal at parturition plays an important role in initiating maternal behavior in various rodent species. Systemic estrogen treatment shortens the latency to onset of maternal behavior in nulliparous female rats that have not experienced parturition. In contrast, nulliparous laboratory mice show rapid onset of maternal behavior without estrogen treatment, and the role of estrogen still remains unclear. Here the effect of systemic estrogen treatment (for 2 h, 1 day, 3 days, and 7 days) after progesterone withdrawal was examined on maternal behavior of C57BL/6 mice. This estrogen regimen led to different effects on nursing, pup retrieval, and nest building behaviors. Latency to nursing was shortened by estrogen treatment within 2 h. Moreover, pup retrieval and nest building were decreased. mRNA expression was also investigated for estrogen receptor α (ERα) and for genes involved in regulating maternal behavior, specifically, the oxytocin receptor (OTR) and vasopressin receptor in the medial amygdala (MeA) and medial preoptic area (MPOA). Estrogen treatment led to decreased ERα mRNA in both regions. Although OTR mRNA was increased in the MeA, OTR and vasopressin receptor mRNA were reduced in the MPOA, showing region-dependent transcription regulation. To determine the mechanisms for the actions of estrogen treatment, the contribution of estrogen synthesis in the brain was examined. Blockade of estrogen synthesis in the brain by systemic letrozole treatment in ovariectomized mice interfered with pup retrieval and nest building but not nursing behavior, indicating different contributions of estrogen synthesis to maternal behavior. Furthermore, letrozole treatment led to an increase in ERα mRNA in the MeA but not in the MPOA, suggesting that involvement of estrogen synthesis is brain region dependent. Altogether, these results suggest that region-dependent estrogen synthesis leads to differential transcriptional activation due

  20. Distinct Effects of Estrogen on Mouse Maternal Behavior: The Contribution of Estrogen Synthesis in the Brain

    PubMed Central

    Murakami, Gen

    2016-01-01

    Estrogen surge following progesterone withdrawal at parturition plays an important role in initiating maternal behavior in various rodent species. Systemic estrogen treatment shortens the latency to onset of maternal behavior in nulliparous female rats that have not experienced parturition. In contrast, nulliparous laboratory mice show rapid onset of maternal behavior without estrogen treatment, and the role of estrogen still remains unclear. Here the effect of systemic estrogen treatment (for 2 h, 1 day, 3 days, and 7 days) after progesterone withdrawal was examined on maternal behavior of C57BL/6 mice. This estrogen regimen led to different effects on nursing, pup retrieval, and nest building behaviors. Latency to nursing was shortened by estrogen treatment within 2 h. Moreover, pup retrieval and nest building were decreased. mRNA expression was also investigated for estrogen receptor α (ERα) and for genes involved in regulating maternal behavior, specifically, the oxytocin receptor (OTR) and vasopressin receptor in the medial amygdala (MeA) and medial preoptic area (MPOA). Estrogen treatment led to decreased ERα mRNA in both regions. Although OTR mRNA was increased in the MeA, OTR and vasopressin receptor mRNA were reduced in the MPOA, showing region-dependent transcription regulation. To determine the mechanisms for the actions of estrogen treatment, the contribution of estrogen synthesis in the brain was examined. Blockade of estrogen synthesis in the brain by systemic letrozole treatment in ovariectomized mice interfered with pup retrieval and nest building but not nursing behavior, indicating different contributions of estrogen synthesis to maternal behavior. Furthermore, letrozole treatment led to an increase in ERα mRNA in the MeA but not in the MPOA, suggesting that involvement of estrogen synthesis is brain region dependent. Altogether, these results suggest that region-dependent estrogen synthesis leads to differential transcriptional activation due

  1. 40 CFR 721.3680 - Ethylene oxide adduct of fatty acid ester with pentaerythritol.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Ethylene oxide adduct of fatty acid... New Uses for Specific Chemical Substances § 721.3680 Ethylene oxide adduct of fatty acid ester with... identified generically as ethylene oxide adduct of fatty acid ester with pentaerythritol (PMN P-91-442)...

  2. 40 CFR 721.6205 - Hexamethylenediamine adduct of substituted piperidinyloxy (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Hexamethylenediamine adduct of... Significant New Uses for Specific Chemical Substances § 721.6205 Hexamethylenediamine adduct of substituted... substance identified generically as hexamethylenediamine adduct of substituted piperidinyloxy (PMN...

  3. 40 CFR 721.6205 - Hexamethylenediamine adduct of substituted piperidinyloxy (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hexamethylenediamine adduct of... Significant New Uses for Specific Chemical Substances § 721.6205 Hexamethylenediamine adduct of substituted... substance identified generically as hexamethylenediamine adduct of substituted piperidinyloxy (PMN...

  4. 40 CFR 721.3680 - Ethylene oxide adduct of fatty acid ester with pentaerythritol.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Ethylene oxide adduct of fatty acid... New Uses for Specific Chemical Substances § 721.3680 Ethylene oxide adduct of fatty acid ester with... identified generically as ethylene oxide adduct of fatty acid ester with pentaerythritol (PMN P-91-442)...

  5. 40 CFR 721.3680 - Ethylene oxide adduct of fatty acid ester with pentaerythritol.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Ethylene oxide adduct of fatty acid... New Uses for Specific Chemical Substances § 721.3680 Ethylene oxide adduct of fatty acid ester with... identified generically as ethylene oxide adduct of fatty acid ester with pentaerythritol (PMN P-91-442)...

  6. 40 CFR 721.3680 - Ethylene oxide adduct of fatty acid ester with pentaerythritol.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Ethylene oxide adduct of fatty acid... New Uses for Specific Chemical Substances § 721.3680 Ethylene oxide adduct of fatty acid ester with... identified generically as ethylene oxide adduct of fatty acid ester with pentaerythritol (PMN P-91-442)...

  7. 40 CFR 721.3680 - Ethylene oxide adduct of fatty acid ester with pentaerythritol.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Ethylene oxide adduct of fatty acid... New Uses for Specific Chemical Substances § 721.3680 Ethylene oxide adduct of fatty acid ester with... identified generically as ethylene oxide adduct of fatty acid ester with pentaerythritol (PMN P-91-442)...

  8. Adduct formation and repair, and translesion DNA synthesis across the adducts in human cells exposed to 3-nitrobenzanthrone.

    PubMed

    Kawanishi, Masanobu; Fujikawa, Yoshihiro; Ishii, Hiroshi; Nishida, Hiroshi; Higashigaki, Yuka; Kanno, Takaharu; Matsuda, Tomonari; Takamura-Enya, Takeji; Yagi, Takashi

    2013-05-15

    3-Nitrobenzanthrone (3-nitro-7H-benz[d,e]anthracen-7-one, 3-NBA) is a potent environmental mutagen that is found in diesel exhaust fumes and airborne particulates. It is known to produce several DNA adducts, including three major adducts N-(2'-deoxyguanosin-8-yl)-3-aminobenzanthrone (dG-C8-N-ABA), 2-(2'-deoxyadenosin-N(6)-yl)-3-aminobenzanthrone (dA-N(6)-C2-ABA), and 2-(2'-deoxyguanosin-N(2)-yl)-3-aminobenzanthrone (dG-N(2)-C2-ABA) in mammalian cells. In the present study, we measured the quantity of the formation and subsequent reduction of these adducts in human hepatoma HepG2 cells that had been treated with 3-NBA using LC-MS/MS analysis. As a result, dG-C8-N-ABA and dG-N(2)-C2-ABA were identified as major adducts in the HepG2 cells, and dA-N(6)-C2-ABA was found to be a minor adduct. Treatment with 1μg/mL 3-NBA for 24h induced the formation of 2835±1509 dG-C8-N-ABA and 3373±1173 dG-N(2)-C2-ABA per 10(7) dG and 877±330 dA-N(6)-C2-ABA per 10(7) dA in the cells. The cellular DNA repair system removed the dG-C8-N-ABA and dA-N(6)-C2-ABA adducts more efficiently than the dG-N(2)-C2-ABA adducts. After a 24-h repair period, 86.4±11.1% of the dG-N(2)-C2-ABA adducts remained, whereas only 51.7±2.7% of the dG-C8-N-ABA adducts and 37.8±1.7% of the dA-N(6)-C2-ABA adducts were present in the cells. We also evaluated the efficiency of bypasses across these three adducts and their mutagenic potency by introducing site-specific mono-modified plasmids into human cells. This translesion DNA synthesis (TLS) assay showed that dG-C8-N-ABA blocked DNA replication markedly (its replication frequency was 16.9±2.7%), while the replication arrests induced by dG-N(2)-C2-ABA and dA-N(6)-C2-ABA were more moderate (their replication frequencies were 33.3±6.2% and 43.1±7.5%, respectively). Mutagenic TLS was observed more frequently in replication across dG-C8-N-ABA (30.6%) than in replication across dG-N(2)-C2-ABA (12.1%) or dA-N(6)-C2-ABA (12.1%). These findings provide important

  9. Conformations of DNA adducts with polycyclic aromatic carcinogens

    SciTech Connect

    Broyde, S.; Hingerty, B.

    1984-01-01

    Minimized semi-empirical potential energy calculations for a number of carcinogen adducts with dCpdG have yielded molecular views of the adduct conformations. The base displaced and Z type conformations of acetylaminofluorene (AAF) adducts to guanine C-8 have been detailed. Model building shows that base displacement causes kinking and denaturation in the B helix, while the Z helix is largely unperturbed by modification with AAF, in agreement with experimental findings. The minor AAF adduct linked to quanine N/sup 2/ can reside at a B-Z junction, with the carcinogen buried in a groove in the Z direction, without causing denaturation. The syn guanine in these modified Z forms could be mutagenic, the lesion escaping repair because the helix is undeformed, while the distorted base-displaced conformers are repaired. Aminofluorene (AF) and 4-aminobiphenyl (ABP) linked to guanine N/sup 2/ are currently believed to be critical lesions. They all have a pair of A or B type low energy states, one of which has base-base stacking with carcinogen at the helix exterior, and a second with carcinogen-base stacking. The two states are easily interconvertible. It is possible that the carcinogen may reside primarily at the unperturbed helix exterior where it escapes repair, but that carcinogen-base stacking may occur at a critical time during replication, leading to a mutation. 49 references, 8 figures.

  10. Mass Spectrometric Analyses of Organophosphate Insecticide Oxon Protein Adducts

    PubMed Central

    Thompson, Charles M.; Prins, John M.; George, Kathleen M.

    2010-01-01

    Objective Organophosphate (OP) insecticides continue to be used to control insect pests. Acute and chronic exposures to OP insecticides have been documented to cause adverse health effects, but few OP-adducted proteins have been correlated with these illnesses at the molecular level. Our aim was to review the literature covering the current state of the art in mass spectrometry (MS) used to identify OP protein biomarkers. Data sources and extraction We identified general and specific research reports related to OP insecticides, OP toxicity, OP structure, and protein MS by searching PubMed and Chemical Abstracts for articles published before December 2008. Data synthesis A number of OP-based insecticides share common structural elements that result in predictable OP–protein adducts. The resultant OP–protein adducts show an increase in molecular mass that can be identified by MS and correlated with the OP agent. Customized OP-containing probes have also been used to tag and identify protein targets that can be identified by MS. Conclusions MS is a useful and emerging tool for the identification of proteins that are modified by activated organophosphate insecticides. MS can characterize the structure of the OP adduct and also the specific amino acid residue that forms the key bond with the OP. Each protein that is modified in a unique way by an OP represents a unique molecular biomarker that with further research can lead to new correlations with exposure. PMID:20056576

  11. Selective estrogen modulators in menopause.

    PubMed

    Gambacciani, M

    2013-12-01

    Hypoestrogenism is the primary etiologic factor for osteoporosis and related fractures, as well as for a number of clinical symptoms that can reduce the quality of life in postmenopausal women. Alternative to classical hormone replacement therapy (HRT) are needed for women that cannot or don't want to be treated with hormones. Selective estrogen receptor modulators (SERMs) are compounds that lack the steroid structure of estrogens, but interact with estrogen receptors (ERs) as agonists or antagonists depending on the target tissue. Tamoxifen, the first generation of SERMs, has been used for decades in the primary prevention and treatment of breast cancer. Tamoxifen exerts positive estrogenic effect on bone protecting bone mineral density (BMD). However, tamoxifen acts as agonist also on the endometrium, leading to an increased risk of endometrial hyperplasia and cancer. In addition, tamoxifen administration is associated with significantly increased risks of stroke, venous thromboembolism, including both deep-vein thrombosis and pulmonary emboli. Thus, these actions, in addition to the increased risk of and hot flushes, prevent the use of tamoxifen for the prevention of osteoporosis. Further generations of SERM, Raloxifene and bazedoxifene were developed for the prevention and treatment of postmenopausal osteoporosis and are now licensed for this indication. In addition. Raloxifene is as effective as tamoxifen in reducing the risk of invasive breast cancer. On the other hand, the available data indicate that Bazedoxifene exerts a greater anti-fracture activity than Raloxifene. At variance of tamoxifen, both raloxifene and bazedoxifene reduce the risk of endometrial hyperplasia and cancer. However, they are associated with a significant increase the risks of venous thromboembolic events. Although raloxifene and Bazedoxifene prevent postmenopausal osteoporosis, they have not been associated with reductions in climacteric symptoms, particularly hot flushes. In order

  12. A selective de-O-methylation of guaiacyl lignans to corresponding catechol derivatives by 2-iodoxybenzoic acid (IBX). The role of the catechol moiety on the toxicity of lignans.

    PubMed

    Bernini, Roberta; Barontini, Maurizio; Mosesso, Pasquale; Pepe, Gaetano; Willför, Stefan M; Sjöholm, Rainer E; Eklund, Patrik C; Saladino, Raffaele

    2009-06-01

    We report here the first selective de-O-methylation of a large panel of guaiacyl lignans to the corresponding catechol derivatives by using IBX as primary oxidant under green conditions (dimethyl carbonate-H(2)O solvent) through an in situ reduction procedure. The influence of the catechol moiety on the cytotoxicity and genotoxicity of new lignan derivatives has been investigated. The results obtained indicated that the presence of the catechol moiety sharply enhances the clastogenic potential (e.g. induction of chromosomal aberrations), the cytotoxicity and the modulation of cell cycle progression with respect to the parent compounds. Thus, despite the in vitro antioxidant activity usually described for catechol derivatives, our results show for the first time the generation of a clastogenic potential, highly indicative of a long-term genetic and cancer risk.

  13. Ion-molecule adduct formation in tandem mass spectrometry.

    PubMed

    Alechaga, Élida; Moyano, Encarnación; Galceran, Maria Teresa

    2016-02-01

    Nowadays most LC-MS methods rely on tandem mass spectrometry not only for quantitation and confirmation of compounds by multiple reaction monitoring (MRM), but also for the identification of unknowns from their product ion spectra. However, gas-phase reactions between charged and neutral species inside the mass analyzer can occur, yielding product ions at m/z values higher than that of the precursor ion, or at m/z values difficult to explain by logical losses, which complicate mass spectral interpretation. In this work, the formation of adduct ions in the mass analyzer was studied using several mass spectrometers with different mass analyzers (ion trap, triple quadrupole, and quadrupole-Orbitrap). Heterocyclic amines (AαC, MeAαC, Trp-P-1, and Trp-P-2), photo-initiators (BP and THBP), and pharmaceuticals (phenacetin and levamisole) were selected as model compounds and infused in LCQ Classic, TSQ Quantum Ultra AM, and Q-Exactive Orbitrap (ThermoFisher Scientific) mass spectrometers using electrospray as ionization method. The generation of ion-molecule adducts depended on the compound and also on the instrument employed. Adducts with neutral organic solvents (methanol and acetonitrile) were only observed in the ion trap instrument (LCQ Classic), because of the ionization source on-axis configuration and the lack of gas-phase barriers, which allowed inertial entrance of the neutrals into the analyzer. Adduct formation (only with water) in the triple quadrupole instruments was less abundant than in the ion trap and quadrupole-Orbitrap mass spectrometers, because of the lower residence time of the reactive product ions in the mass analyzer. The moisture level of the CID and/or damper gas had a great effect in beam-like mass analyzers such as triple quadrupole, but not in trap-like mass analyzers, probably because of the long residence time that allowed adduct formation even with very low concentrations of water inside the mass spectrometer. PMID:26700446

  14. Analysis of lagoon samples from different concentrated animal feeding operations for estrogens and estrogen conjugates.

    PubMed

    Hutchins, Stephen R; White, Mark V; Hudson, Felisa M; Fine, Dennis D

    2007-02-01

    Although Concentrated Animal Feeding Operations (CAFOs) have been identified as potentially important sources for the release of estrogens into the environment, information is lacking on the concentrations of estrogens in whole lagoon effluents (including suspended solids) which are used for land application. Lagoons associated with swine, poultry, and cattle operations were sampled at three locations each for direct analysis for estrogens by GC/ MS/MS and estrogen conjugates by LC/MS/MS. Estrogen conjugates were also analyzed indirectly by first subjecting the same samples to enzyme hydrolysis. Solids from centrifuged samples were extracted for free estrogens to estimate total estrogen load. Total free estrogen levels (estrone, 17alpha-estradiol, 17beta-estradiol, estriol) were generally higher in swine primary (1000-21000 ng/L), followed by poultry primary (1800-4000 ng/L), dairy secondary (370-550 ng/L), and beef secondary (22-24 ng/L) whole lagoon samples. Swine and poultry lagoons contained levels of 17(alpha-estradiol comparable to those of 17beta-estradiol. Confirmed estrogen conjugates included estrone-3-sulfate (2-91 ng/L), 17beta-estradiol-3-sulfate (8-44 ng/L), 17alpha-estradiol-3-sulfate (141-182 ng/L), and 17beta-estradiol-17-sulfate (72-84 ng/L) in some lagoons. Enzymatic hydrolysis indicated the presence of additional unidentified estrogen conjugates not detected bythe LC/MS/MS method. In most cases estrogen conjugates accounted for at least a third of the total estrogen equivalents. Collectively, these methods can be used to better determine estrogen loads from CAFO operations, and this research shows that estrogen conjugates contribute significantly to the overall estrogen load, even in different types of CAFO lagoons. PMID:17328177

  15. Chloroethyinitrosourea-derived ethano cytosine and adenine adducts are substrates for escherichia coli glycosylases excising analogous etheno adducts

    SciTech Connect

    Guliaev, Anton B.; Singer, B.; Hang, Bo

    2004-05-05

    Exocyclic ethano DNA adducts are saturated etheno ring derivatives formed mainly by therapeutic chloroethylnitrosoureas (CNUs), which are also mutagenic and carcinogenic. In this work, we report that two of the ethano adducts, 3,N{sup 4}-ethanocytosine (EC) and 1,N{sup 6}-ethanoadenine (EA), are novel substrates for the Escherichia coli mismatch-specific uracil-DNA glycosylase (Mug) and 3-methyladenine DNA glycosylase II (AlkA), respectively. It has been shown previously that Mug excises 3,N{sup 4}-ethenocytosine ({var_epsilon}C) and AlkA releases 1,N{sup 6}-ethenoadenine ({var_epsilon}A). Using synthetic oligonucleotides containing a single ethano or etheno adduct, we found that both glycosylases had a {approx}20-fold lower excision activity toward EC or EA than that toward their structurally analogous {var_epsilon}C or {var_epsilon}A adduct. Both enzymes were capable of excising the ethano base paired with any of the four natural bases, but with varying efficiencies. The Mug activity toward EC could be stimulated by E. coli endonuclease IV and, more efficiently, by exonuclease III. Molecular dynamics (MD) simulations showed similar structural features of the etheno and ethano derivatives when present in DNA duplexes. However, also as shown by MD, the stacking interaction between the EC base and Phe 30 in the Mug active site is reduced as compared to the {var_epsilon}C base, which could account for the lower EC activity observed in this study.

  16. Photochemistry of psoralen-DNA adducts, biological effects of psoralen-DNA adducts, applications of psoralen-DNA photochemistry

    SciTech Connect

    Shi, Yun-bo

    1988-03-01

    This thesis consists of three main parts and totally eight chapters. In Part I, The author will present studies on the photochemistry of psoralen-DNA adducts, specifically, the wavelength dependencies for the photoreversals of thymidine-HMT (4'-hydroxymethyl-4, 5', 8-trimenthylpsoralen) monoadducts and diadduct and the same adducts incorporated in DNA helices and the wavelength dependecies for the photocrossslinking of thymidine-HMT monoadducts in double-stranded helices. In Part II, The author will report some biological effects of psoralen-DNA adducts, i.e., the effects on double-stranded DNA stability, DNA structure, and transcription by E. coli and T7 RNA polymerases. Finally, The author will focus on the applications of psoralen-DNA photochemistry to investigation of protein-DNA interaction during transcription, which includes the interaction of E. coli and T7 RNA polymerases with DNA in elongation complexes arrested at specific psoralen-DNA adduct sites as revealed by DNase I footprinting experiments. 123 refs., 52 figs., 12 tabs.

  17. Diet and urinary estrogen profile in premenopausal omnivorous and vegetarian women and in premenopausal women with breast cancer.

    PubMed

    Adlercreutz, H; Fotsis, T; Höckerstedt, K; Hämäläinen, E; Bannwart, C; Bloigu, S; Valtonen, A; Ollus, A

    1989-01-01

    The urinary estrogen profile was studied in the midfollicular phase twice, and diet four times during 1 yr in 10 premenopausal breast cancer (BC) patients consuming an omnivorous normal Finnish diet and in two control groups, one consuming an omnivorous (n = 12) and the other a lactovegetarian (n = 11) diet. Total fat intake in relation to caloric intake was almost identical in all three groups. Only with regard to grain fiber intake did the BC patients differ significantly from both other groups. No differences were found between the groups with regard to urinary excretion of 13 individual estrogens and total estrogens, with the exception of 4-hydroxyestrone (4-OH-E1), which was significantly lower (P less than 0.05) in the BC group than in the vegetarians. A high carbohydrate to protein ratio in the diet had a negative correlation with the excretion of 2-hydroxyestrogens and 2-hydroxyesterone (2-OH-E1) to 4-OH-E1 ratio. The BC group had significantly higher urinary 2-OH-E1 to E1 ratio (P less than 0.05) compared to the vegetarians. The 2-OH-E1 to 4-OH-E1 ratio was highest in the BC group (= 7.1) and differed significantly from that of the omnivores (= 4.3; P less than 0.02) and vegetarians (= 3.6; P less than 0.005). This ratio showed a negative correlation with intake of carbohydrates, starch, total and grain fiber. Urinary excretion of 4-OH-E1 correlated positively with total and grain fiber intake and plasma SHBG. Protein intake correlated positively with urinary 2-methoxy-E1 excretion, and retinol intake positively with catechol estrogen, E1 and E2 excretion. It is concluded that estrogen production and urinary estrogen profile in premenopausal breast cancer patients is normal with the exception of a low 4-OH-E1 excretion and high urinary 2-OH-E1 to 4-OH-E1 ratio. This ratio, which seems to depend on diet, is the only urinary estrogen parameter separating premenopausal BC patients from the control omnivorous and lactovegetarian women.

  18. Regulation of aromatics biodegradation by rhl quorum sensing system through induction of catechol meta-cleavage pathway.

    PubMed

    Yong, Yang-Chun; Zhong, Jian-Jiang

    2013-05-01

    The mechanism for quorum sensing (QS) regulation on aromatics degradation was investigated. Deletion of rhl QS system resulted in a significant decrease in aromatics biodegradation as well as the activity of catechol 2,3-dioxygenase (C23O, key enzyme for catechol meta-cleavage pathway) in Pseudomonas aeruginosa CGMCC1.860. Interestingly, this repression could be relieved by N-butyryl homoserine lactone (the signaling molecule of rhl QS system) addition. In accordance, the transcription level of nahH (the gene encoding C23O) and nahR (transcriptional activator) also responded to rhl perturbation in a similar way. The results indicated that rhl QS system positively controlled the catechol meta-cleavage pathway, and hence improved aromatics biodegradation. It suggested manipulation of QS system could be a promising strategy to tune the catechol cleavage pathway and to control aromatics biodegradation.

  19. Synthesis and structure/antioxidant activity relationship of novel catecholic antioxidant structural analogues to hydroxytyrosol and its lipophilic esters.

    PubMed

    Bernini, Roberta; Crisante, Fernanda; Barontini, Maurizio; Tofani, Daniela; Balducci, Valentina; Gambacorta, Augusto

    2012-08-01

    A large panel of novel catecholic antioxidants and their fatty acid or methyl carbonate esters has been synthesized in satisfactory to good yields through a 2-iodoxybenzoic acid (IBX)-mediated aromatic hydroxylation as the key step. The new catechols are structural analogues of naturally occurring hydroxytyrosol (3,4-DHE). To evaluate structure/activity relationships, the antioxidant properties of all catecholic compounds were evaluated in vitro by ABTS assay and on whole cells by DCF fluorometric assay and compared with that of the corresponding already known hydroxytyrosyl derivatives. Results outline that all of the new catechols show antioxidant capacity in vitro higher than that of the corresponding hydroxytyrosyl derivatives. Less evident positive effects have been detected in whole cells experiments. Cytotoxicity experiments, using MTT assay, on a representative set of compounds evidenced no influence in cell survival.

  20. The csbX gene of Azotobacter vinelandii encodes an MFS efflux pump required for catecholate siderophore export.

    PubMed

    Page, William J; Kwon, Elena; Cornish, Anthony S; Tindale, Anne E

    2003-11-21

    The csbX gene of Azotobacter vinelandii was regulated in an iron-repressible manner from a divergent promoter upstream of the catecholate siderophore biosynthesis (csb) operon and was predicted to encode an efflux pump of the major facilitator superfamily. Other proteins that were most similar to CsbX were encoded by genes found in the catecholate siderophore biosynthesis operons of Aeromonas hydrophila and Stigmatella aurantiaca. Inactivation of csbX resulted in 57-100% decrease in the amount of catecholates released when compared to the wild-type in iron-limited medium. CsbX was most important for the export of the high affinity chelator protochelin with the majority of the catecholates released by csbX mutants being the protochelin intermediates azotochelin and aminochelin.

  1. Role of estrogen in avian osteoporosis.

    PubMed

    Beck, M M; Hansen, K K

    2004-02-01

    One of the difficulties associated with commercial layer production is the development of osteoporosis in hens late in the production cycle. In light of this fact and because of hens' unique requirements for Ca, many studies have focused on the regulation of Ca and the role of estrogen in this process. The time course of estrogen synthesis over the productive life of hens has been well documented; increased circulating estrogen accompanies the onset of sexual maturity while decreases signal a decline in egg production prior to a molt. Numbers of estrogen receptors decrease with age in numerous tissues. The parallel changes in calcium-regulating proteins, primarily Calbindin D28K, and in the ability of duodenal cells to transport Ca, are thought to occur as a result of the changes in estrogen, and are also reversible by the molt process. In addition to the traditional model of estrogen action, evidence now exists for a possible nongenomic action of estrogen via membrane-bound receptors, demonstrated by extremely rapid surges of ionized Ca in chicken granulosa cells in response to 17beta-estradiol. Estrogen receptors have also been discovered in duodenal tissue, and tamoxifen, which binds to the estrogen receptor, has been shown to cause a rapid increase in Ca transport in the duodenum. In addition, recent evidence also suggests that mineralization of bone per se may not explain entirely the etiology of osteoporosis in the hen but that changes in the collagen matrix may contribute through decreases in bone elasticity. Taken together, these studies suggest that changes in estrogen synthesis and estrogen receptor populations may underlie the age-related changes in avian bone. As with postmenopausal women, dietary Ca and vitamin D are of limited benefit as remedies for osteoporosis in the hen. PMID:14979570

  2. 32P-postlabeling DNA adduct assay: cigarette smoke-induced dna adducts in the respiratory and nonrespiratory rat tissues. Book chapter

    SciTech Connect

    Gupta, R.C.; Gairola, C.G.

    1990-01-01

    An analysis of the tissue DNA adducts in rats by the sensitive (32)p-postlabeling assay showed one to eight detectable DNA adducts in lung, trachea, larynx, heart and bladder of the sham controls. Chronic exposure of animals to mainstream cigarette smoke showed a remarkable enhancement of most adducts in the lung and heart DNA. Since cigarette smoke contains several thousand chemicals and a few dozen of them are known or potential carcinogens, the difference between the DNA adducts of nasal and the other tissues may reflect the diversity of reactive constituents and their differential absorption in different tissues. In comparison to the lung DNA adducts, the adducts in nasal DNA were less hydrophobic. Identity of the predominant adducts was further investigated by comparison with several reference DNA adducts from 10 PAH and aromatic amines. Since some of these chemicals are present in cigarette smoke, the results suggest that these constituents of cigarette smoke may not be directly responsible for formation of DNA adducts in the lung and heart of the smoke-exposed animals.

  3. Differential inhibition of DNA synthesis in human T cells by the cigarette tar components hydroquinone and catechol.

    PubMed

    Li, Q; Aubrey, M T; Christian, T; Freed, B M

    1997-08-01

    Hydroquinone (HQ), catechol, and phenol exist in microgram quantities in cigarette tar and represent the predominant form of human exposure to benzene. Exposure of human T lymphoblasts (HTL) in vitro to 50 microM HQ or 50 microM catechol decreased IL-2-dependent DNA synthesis and cell proliferation by >90% with no effect on cell viability. Phenol had no effect on HTL proliferation at concentrations up to 1 mm. The addition of HQ or catechol to proliferating HTL blocked 3H-TdR uptake by >90% within 2 hr without significantly affecting 3H-UR uptake, suggesting that both compounds inhibit a rate-limiting step in DNA synthesis. However, the effects of HQ and catechol appear to involve different mechanisms. Ferric chloride (FeCl3) reversed the inhibitory effect of catechol, but not HQ, corresponding with the known ability of catechol to chelate iron. HQ, but not catechol, caused a decrease in transferrin receptor (TfR, CD71) expression, comparable to the level observed in IL-2-starved cells. HQ also inhibited DNA synthesis in cultures of transformed Jurkat T lymphocytes, primary and transformed fibroblasts, and mink lung epithelial cells, indicating that its antiproliferative effect was not restricted to IL-2 mediated proliferation. However, DNA synthesis by primary lymphocytes was more sensitive to HQ (IC50 = 6 microM) than that of the transformed Jurkat T cell line (IC50 = 37 microM) or primary human fibroblasts (IC50 = 45 microM), suggesting that normal lymphocytes may be particularly sensitive to HQ. The effects of HQ and catechol on DNA synthesis could be partially reversed by a combination of adenosine deoxyribose and guanosine deoxyribose, suggesting that both compounds may inhibit ribonucleotide reductase.

  4. Detection of Adriamycin-DNA adducts by accelerator mass spectrometry at clinically relevant Adriamycin concentrations.

    PubMed

    Coldwell, Kate E; Cutts, Suzanne M; Ognibene, Ted J; Henderson, Paul T; Phillips, Don R

    2008-09-01

    Limited sensitivity of existing assays has prevented investigation of whether Adriamycin-DNA adducts are involved in the anti-tumour potential of Adriamycin. Previous detection has achieved a sensitivity of a few Adriamycin-DNA adducts/10(4) bp DNA, but has required the use of supra-clinical drug concentrations. This work sought to measure Adriamycin-DNA adducts at sub-micromolar doses using accelerator mass spectrometry (AMS), a technique with origins in geochemistry for radiocarbon dating. We have used conditions previously validated (by less sensitive decay counting) to extract [(14)C]Adriamycin-DNA adducts from cells and adapted the methodology to AMS detection. Here we show the first direct evidence of Adriamycin-DNA adducts at clinically-relevant Adriamycin concentrations. [(14)C]Adriamycin treatment (25 nM) resulted in 4.4 +/- 1.0 adducts/10(7) bp ( approximately 1300 adducts/cell) in MCF-7 breast cancer cells, representing the best sensitivity and precision reported to date for the covalent binding of Adriamycin to DNA. The exceedingly sensitive nature of AMS has enabled over three orders of magnitude increased sensitivity of Adriamycin-DNA adduct detection and revealed adduct formation within an hour of drug treatment. This method has been shown to be highly reproducible for the measurement of Adriamycin-DNA adducts in tumour cells in culture and can now be applied to the detection of these adducts in human tissues.

  5. Estrogen receptor variant ER-α36 is involved in estrogen neuroprotection against oxidative toxicity.

    PubMed

    Han, S; Zhao, B; Pan, X; Song, Z; Liu, J; Gong, Y; Wang, M

    2015-12-01

    It is well known that estrogen exerts neuroprotective effect against various neuronal damages. However, the estrogen receptor (ER) that mediates estrogen neuroprotection has not been well established. In this study, we investigated the potential receptor that mediates estrogen neuroprotection and the underlying molecular mechanisms. Hydrogen peroxide (H2O2) was chosen as an agent in our study to mimic free radicals that are often involved in the pathogenesis of many degenerative diseases. We found that in human SY5Y and IMR-32 cells, the estrogen neuroprotection against H2O2 toxicity was abrogated by knockdown of a variant of estrogen receptor-α, ER-α36. We also studied the rapid estrogen signaling mediated by ER-α36 in neuroprotective effect and found the PI3K/AKT and MAPK/ERK1/2 signaling mediated by ER-α36 is involved in estrogen neuroprotection. We also found that GPER, an orphan G protein-coupled receptor, is not involved in ER-α36-mediated rapid estrogen response. Our study thus demonstrates that ER-α36-mediated rapid estrogen signaling is involved in the neuroprotection activity of estrogen against oxidative toxicity. PMID:26383254

  6. Parabens inhibit human skin estrogen sulfotransferase activity: possible link to paraben estrogenic effects.

    PubMed

    Prusakiewicz, Jeffery J; Harville, Heather M; Zhang, Yanhua; Ackermann, Chrisita; Voorman, Richard L

    2007-04-11

    Parabens (p-hydroxybenzoate esters) are a group of widely used preservatives in topically applied cosmetic and pharmaceutical products. Parabens display weak associations with the estrogen receptors in vitro or in cell based models, but do exhibit estrogenic effects in animal models. It is our hypothesis that parabens exert their estrogenic effects, in part, by elevating levels of estrogens through inhibition of estrogen sulfotransferases (SULTs) in skin. We report here the results of a structure-activity-relationship of parabens as inhibitors of estrogen sulfation in human skin cytosolic fractions and normal human epidermal keratinocytes. Similar to reports of paraben estrogenicity and estrogen receptor affinity, the potency of SULT inhibition increased as the paraben ester chain length increased. Butylparaben was found to be the most potent of the parabens in skin cytosol, yielding an IC(50) value of 37+/-5 microM. Butylparaben blocked the skin cytosol sulfation of estradiol and estrone, but not the androgen dehydroepiandrosterone. The parabens were also tested as inhibitors of SULT activity in a cellular system, with normal human epidermal keratinocytes. The potency of butylparaben increased three-fold in these cells relative to the IC(50) value from skin cytosol. Overall, these results suggest chronic topical application of parabens may lead to prolonged estrogenic effects in skin as a result of inhibition of estrogen sulfotransferase activity. Accordingly, the skin anti-aging benefits of many topical cosmetics and pharmaceuticals could be derived, in part, from the estrogenicity of parabens.

  7. Identification of estrogenic/anti-estrogenic compounds in diesel exhaust particulate extract.

    PubMed

    Noguchi, Keiko; Toriba, Akira; Chung, Sang Woon; Kizu, Ryoichi; Hayakawa, Kazuichi

    2007-11-01

    Diesel exhaust particulate extract (DEPE) was obtained from diesel exhaust particulates with Soxhlet extraction using dichloromethane. After separating DEPE into 11 fractions by liquid-liquid extraction, the neutral fraction (N) showed anti-estrogenic activity and the weak acid (phenol) fraction (WA(P)) showed estrogenic and anti-estrogenic activities by a yeast two-hybrid assay system expressing human estrogen receptor alpha. Both fractions were thoroughly fractionated by silica gel column chromatography and reversed-phase HPLC. In the WA(P) fraction, 3-methyl-4-nitrophenol and 2,6-dimethyl-4-nitrophenol were identified by LC-MS/MS as estrogenic compounds. This is the first study to identify 2,6-dimethyl-4-nitrophenol in DEPE and the first study to show that it is an estrogenic compound. In the N fraction, 1-hydroxypyrene was also identified by LC-MS/MS as an anti-estrogenic compound.

  8. Human Biomonitoring of DNA Adducts by Ion Trap Multistage Mass Spectrometry.

    PubMed

    Guo, Jingshu; Turesky, Robert J

    2016-01-01

    Humans are continuously exposed to hazardous chemicals in the environment. These chemicals or their electrophilic metabolites can form adducts with genomic DNA, which can lead to mutations and the initiation of cancer. The identification of DNA adducts is required for understanding exposure and the etiological role of a genotoxic chemical in cancer risk. The analytical chemist is confronted with a great challenge because the levels of DNA adducts generally occur at <1 adduct per 10(7) nucleotides, and the amount of tissue available for measurement is limited. Ion trap mass spectrometry has emerged as an important technique to screen for DNA adducts because of the high level sensitivity and selectivity, particularly when employing multi-stage scanning (MS(n) ). The product ion spectra provide rich structural information and corroborate the adduct identities even at trace levels in human tissues. Ion trap technology represents a significant advance in measuring DNA adducts in humans. © 2016 by John Wiley & Sons, Inc. PMID:27584705

  9. pH-dependent cross-linking of catechols through oxidation via Fe(3+) and potential implications for mussel adhesion.

    PubMed

    Fullenkamp, Dominic E; Barrett, Devin G; Miller, Dusty R; Kurutz, Josh W; Messersmith, Phillip B

    2014-01-01

    The mussel byssus is a remarkable attachment structure that is formed by injection molding and rapid in-situ hardening of concentrated solutions of proteins enriched in the catecholic amino acid 3,4-dihydroxy-L-phenylalanine (DOPA). Fe(3+), found in high concentrations in the byssus, has been speculated to participate in redox reactions with DOPA that lead to protein polymerization, however direct evidence to support this hypothesis has been lacking. Using small molecule catechols, DOPA-containing peptides, and native mussel foot proteins, we report the first direct observation of catechol oxidation and polymerization accompanied by reduction of Fe(3+) to Fe(2+). In the case of the small molecule catechol, we identified two dominant dimer species and characterized their connectivities by nuclear magnetic resonance (NMR), with the C6-C6 and C5-C6 linked species as the major and minor products, respectively. For the DOPA-containing peptide, we studied the pH dependence of the reaction and demonstrated that catechol polymerization occurs readily at low pH, but is increasingly diminished in favor of metal-catechol coordination interactions at higher pH. Finally, we demonstrate that Fe(3+) can induce cross-links in native byssal mussel proteins mefp-1 and mcfp-1 at acidic pH. Based on these findings, we discuss the potential implications to the chemistry of mussel adhesion.

  10. pH-dependent cross-linking of catechols through oxidation via Fe(3+) and potential implications for mussel adhesion.

    PubMed

    Fullenkamp, Dominic E; Barrett, Devin G; Miller, Dusty R; Kurutz, Josh W; Messersmith, Phillip B

    2014-01-01

    The mussel byssus is a remarkable attachment structure that is formed by injection molding and rapid in-situ hardening of concentrated solutions of proteins enriched in the catecholic amino acid 3,4-dihydroxy-L-phenylalanine (DOPA). Fe(3+), found in high concentrations in the byssus, has been speculated to participate in redox reactions with DOPA that lead to protein polymerization, however direct evidence to support this hypothesis has been lacking. Using small molecule catechols, DOPA-containing peptides, and native mussel foot proteins, we report the first direct observation of catechol oxidation and polymerization accompanied by reduction of Fe(3+) to Fe(2+). In the case of the small molecule catechol, we identified two dominant dimer species and characterized their connectivities by nuclear magnetic resonance (NMR), with the C6-C6 and C5-C6 linked species as the major and minor products, respectively. For the DOPA-containing peptide, we studied the pH dependence of the reaction and demonstrated that catechol polymerization occurs readily at low pH, but is increasingly diminished in favor of metal-catechol coordination interactions at higher pH. Finally, we demonstrate that Fe(3+) can induce cross-links in native byssal mussel proteins mefp-1 and mcfp-1 at acidic pH. Based on these findings, we discuss the potential implications to the chemistry of mussel adhesion. PMID:25243062

  11. Development of catechol 2,3-dioxygenase-specific primers for monitoring bioremediation by competitive quantitative PCR

    SciTech Connect

    Mesarch, M.B.; Nakatsu, C.H.; Nies, L.

    2000-02-01

    Benzene, toluene, xylenes, phenol, naphthalene, and biphenyl are among a group of compounds that have at least one reported pathway for biodegradation involving catechol 2,3-dioxygenase enzymes. Thus, detection of the corresponding catechol 2,3-dioxygenase genes can serve as a basis for identifying and quantifying bacteria that have these catabolic abilities. Primes that can successfully amplify a 238-bp catechol 2,3-dioxygenase gene fragment from eight different bacteria are described. The identities of the amplicons were confirmed by hybridization with a 238-bp catechol 2,3-dioxygenase probe. The detection limit was 10{sup 2} to 10{sup 3} gene copies, which was lowered to 10{sup 0} to 10{sup 1} gene copies of hybridization. Using the dioxygenase-specific primers, an increase in catechol 2,3-dioxygenase genes was detected in petroleum-amended soils. The dioxygenase genes were enumerated by competitive quantitative PCR and a 163-bp competitor that was amplified using the same primers. Target and competitor sequences had identical amplification kinetics. Potential PCR inhibitors that could coextract with DNA, nonamplifying DNA, soil factors (humics), and soil pollutants (toluene) did not impact enumeration. Therefore, this technique can be used to accurately and reproducibly quantify catechol 2,3-dioxygenase genes in complex environments such as petroleum-contaminated soil. Direct, non-cultivation-based molecular techniques for detecting and enumerating microbial pollutant-biodegrading genes in environmental samples are powerful tools for monitoring bioremediation and developing field evidence in support of natural attenuation.

  12. Effects of biochar and the geophagous earthworm Metaphire guillelmi on fate of (14)C-catechol in an agricultural soil.

    PubMed

    Shan, Jun; Wang, Yongfeng; Gu, Jianqiang; Zhou, Wenqiang; Ji, Rong; Yan, Xiaoyuan

    2014-07-01

    Both biochar and earthworms can exert influence on behaviors of soil-borne monomeric phenols in soil; however, little was known about the combined effects of biochar and earthworm activities on fate of these chemicals in soil. Using (14)C-catechol as a representative, the mineralization, transformation and residue distribution of phenolic humus monomer in soil amended with different amounts of biochar (0%, 0.05%, 0.5%, and 5%) without/with the geophagous earthworm Metaphire guillelmi were investigated. The results showed biochar at amendment rate <0.5% did not affect (14)C-catechol mineralization, whereas 5% biochar amendment significantly inhibited the mineralization. Earthworms did not affect the mineralization of (14)C-catechol in soil amended with <0.5% biochar, but significantly enhanced the mineralization in 5% biochar amended soil when they were present in soil for 9 d. When earthworms were removed from the soil, the mineralization of (14)C-catechol was significantly lower than that of in earthworm-free soil indicating that (14)C-catecholic residues were stabilized during their passage through earthworm gut. The assimilation of (14)C by earthworms was low (1.2%), and was significantly enhanced by biochar amendment, which was attributed to the release of biochar-associated (14)C-catecholic residues during gut passage of earthworm.

  13. Estrogenic activity of naturally occurring anthocyanidins.

    PubMed

    Schmitt, E; Stopper, H

    2001-01-01

    Anthocyanins, which are natural plant pigments from the flavonoid family, represent substantial constituents of the human diet. Because some other bioflavonoids are known to have estrogenic activity, the aim of this study was to determine the estrogenic activity of the anthocyanine aglycones. Binding affinity to the estrogen receptor-alpha was 10,000- to 20,000-fold lower than that of the endogenous estrogen estradiol. In the estrogen receptor-positive cell line MCF-7, the anthocyanidins induced expression of a reporter gene. The tested anthocyanidins showed estrogen-inducible cell proliferation in two cell lines (MCF-7 and BG-1), but not in the receptor-negative human breast cancer cell line MDA-MB-231. The phytoestrogen-induced cell proliferation could be blocked by addition of the receptor antagonist 4-hydroxytamoxifen. Combination treatments with the endogenous estrogen estradiol resulted in a reduction of estradiol-induced cell proliferation. Overall, the tested anthocyanidins exert estrogenic activity, which might play a role in altering the development of hormone-dependent adverse effects.

  14. Quantum chemical studies of estrogenic compounds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantum chemical methods are potent tools to provide information on the chemical structure and electronic properties of organic molecules. Modern computational chemistry methods have provided a great deal of insight into the binding of estrogenic compounds to estrogenic receptors (ER), an important ...

  15. Estrogen Receptors are Present in Neocortical Transplants

    PubMed Central

    Pedersen, Erik B.; O'Keefe, Joan A.; Handa, Robert J.; Castro, Anthony J.

    1992-01-01

    Fetal neocortical tissue was grafted into neocortical lesion cavities made in newborn rats. After two weeks survival, in vitro binding of [3H]- estradiol to cytosolic preparations provided evidence of estrogen receptors within the transplants. The observed high levels correspond to previous work demonstrating elevated estrogen receptor levels during the first postnatal week in the rat cerebral cortex. PMID:1515481

  16. Crystallization and preliminary X-ray diffraction studies of a catechol-O-methyltransferase/inhibitor complex

    SciTech Connect

    Rodrigues, M. L.; Bonifácio, M. J.; Soares-da-Silva, P.; Carrondo, M. A.; Archer, M.

    2005-01-01

    Catechol-O-methyltransferase has been co-crystallized with a novel inhibitor, which has potential therapeutic application in the Parkinson’s disease therapy. Inhibitors of the enzyme catechol-O-methyltransferase (COMT) are used as co-adjuvants in the therapy of Parkinson’s disease. A recombinant form of the soluble cytosolic COMT from rat has been co-crystallized with a new potent inhibitor, BIA 8-176 [(3,4-dihydroxy-2-nitrophenyl)phenylmethanone], by the vapour-diffusion method using PEG 6K as precipitant. Crystals diffract to 1.6 Å resolution on a synchrotron-radiation source and belong to the monoclinic space group P2{sub 1}, with unit-cell parameters a = 52.77, b = 79.63, c = 61.54 Å, β = 91.14°.

  17. New Hybrid Properties of TiO2 Nanoparticles Surface Modified With Catecholate Type Ligands

    PubMed Central

    2010-01-01

    Surface modification of nanocrystalline TiO2 particles (45 Å) with bidentate benzene derivatives (catechol, pyrogallol, and gallic acid) was found to alter optical properties of nanoparticles. The formation of the inner-sphere charge–transfer complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites. The binding structures were investigated by using FTIR spectroscopy. The investigated ligands have the optimal geometry for chelating surface Ti atoms, resulting in ring coordination complexes (catecholate type of binuclear bidentate binding–bridging) thus restoring in six-coordinated octahedral geometry of surface Ti atoms. From the Benesi–Hildebrand plot, the stability constants at pH 2 of the order 103 M−1 have been determined. PMID:20652142

  18. New Hybrid Properties of TiO2 Nanoparticles Surface Modified With Catecholate Type Ligands

    NASA Astrophysics Data System (ADS)

    Janković, Ivana A.; Šaponjić, Zoran V.; Džunuzović, Enis S.; Nedeljković, Jovan M.

    2010-01-01

    Surface modification of nanocrystalline TiO2 particles (45 Å) with bidentate benzene derivatives (catechol, pyrogallol, and gallic acid) was found to alter optical properties of nanoparticles. The formation of the inner-sphere charge-transfer complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites. The binding structures were investigated by using FTIR spectroscopy. The investigated ligands have the optimal geometry for chelating surface Ti atoms, resulting in ring coordination complexes (catecholate type of binuclear bidentate binding-bridging) thus restoring in six-coordinated octahedral geometry of surface Ti atoms. From the Benesi-Hildebrand plot, the stability constants at pH 2 of the order 103 M-1 have been determined.

  19. Regiocomplementary O-Methylation of Catechols by Using Three-Enzyme Cascades.

    PubMed

    Siegrist, Jutta; Aschwanden, Simon; Mordhorst, Silja; Thöny-Meyer, Linda; Richter, Michael; Andexer, Jennifer N

    2015-12-01

    S-Adenosylmethionine (SAM)-dependent enzymes have great potential for selective alkylation processes. In this study we investigated the regiocomplementary O-methylation of catechols. Enzymatic methylation is often hampered by the need for a stoichiometric supply of SAM and the inhibitory effect of the SAM-derived byproduct on most methyltransferases. To counteract these issues we set up an enzyme cascade. Firstly, SAM was generated from l-methionine and ATP by use of an archaeal methionine adenosyltransferase. Secondly, 4-O-methylation of the substrates dopamine and dihydrocaffeic acid was achieved by use of SafC from the saframycin biosynthesis pathway in 40-70 % yield and high selectivity. The regiocomplementary 3-O-methylation was catalysed by catechol O-methyltransferase from rat. Thirdly, the beneficial influence of a nucleosidase on the overall conversion was demonstrated. The results of this study are important milestones on the pathway to catalytic SAM-dependent alkylation processes.

  20. Synthesis, crystal structure and EPR spectra of cis-dioxo-molybdenum(V) with catechol ligand

    NASA Astrophysics Data System (ADS)

    Lu, Xiaoming; Liu, Shuncheng; Mao, Xian; Bu, Xianhe

    2001-05-01

    The cis-dioxo-molybdenum(V) complex anion [Mo (V)O 2(C 6H 4O 2) 2] 3- was obtained by the reaction of tetra-butyl ammonium β-octamolybdate with catechol and ethylenediamine in the mixed solvent of CH 3OH and CH 3CN, and characterized by IR, NM, UV, EPR spectroscopy and X-ray diffraction with its discrete (NH 2CH 2CH 2NH 3) + cations. The determination of single crystal X-ray analysis revealed that the metal center exhibits distorted octahedral co-ordination with cis dioxo catechol. The result of essentially the same of EPR spectra shown by the complex and flavoenzyme suggests that the title complex anion and flavoenzyme have related structure feature.

  1. Regiocomplementary O-Methylation of Catechols by Using Three-Enzyme Cascades.

    PubMed

    Siegrist, Jutta; Aschwanden, Simon; Mordhorst, Silja; Thöny-Meyer, Linda; Richter, Michael; Andexer, Jennifer N

    2015-12-01

    S-Adenosylmethionine (SAM)-dependent enzymes have great potential for selective alkylation processes. In this study we investigated the regiocomplementary O-methylation of catechols. Enzymatic methylation is often hampered by the need for a stoichiometric supply of SAM and the inhibitory effect of the SAM-derived byproduct on most methyltransferases. To counteract these issues we set up an enzyme cascade. Firstly, SAM was generated from l-methionine and ATP by use of an archaeal methionine adenosyltransferase. Secondly, 4-O-methylation of the substrates dopamine and dihydrocaffeic acid was achieved by use of SafC from the saframycin biosynthesis pathway in 40-70 % yield and high selectivity. The regiocomplementary 3-O-methylation was catalysed by catechol O-methyltransferase from rat. Thirdly, the beneficial influence of a nucleosidase on the overall conversion was demonstrated. The results of this study are important milestones on the pathway to catalytic SAM-dependent alkylation processes. PMID:26437744

  2. The effects of estrogen in ischemic stroke.

    PubMed

    Koellhoffer, Edward C; McCullough, Louise D

    2013-08-01

    Stroke is a leading cause of death and the most common cause of long-term disability in the USA. Women have a lower incidence of stroke compared with men throughout most of the lifespan which has been ascribed to protective effects of gonadal steroids, most notably estrogen. Due to the lower stroke incidence observed in pre-menopausal women and robust preclinical evidence of neuroprotective and anti-inflammatory properties of estrogen, researchers have focused on the potential benefits of hormones to reduce ischemic brain injury. However, as women age, they are disproportionately affected by stroke, coincident with the loss of estrogen with menopause. The risk of stroke in elderly women exceeds that of men and it is clear that in some settings estrogen can have pro-inflammatory effects. This review will focus on estrogen and inflammation and its interaction with aging.

  3. Computational Investigation of the Interplay of Substrate Positioning and Reactivity in Catechol O-Methyltransferase

    PubMed Central

    Patra, Niladri; Ioannidis, Efthymios I.

    2016-01-01

    Catechol O-methyltransferase (COMT) is a SAM- and Mg2+-dependent methyltransferase that regulates neurotransmitters through methylation. Simulations and experiments have identified divergent catecholamine substrate orientations in the COMT active site: molecular dynamics simulations have favored a monodentate coordination of catecholate substrates to the active site Mg2+, and crystal structures instead preserve bidentate coordination along with short (2.65 Å) methyl donor-acceptor distances. We carry out longer dynamics (up to 350 ns) to quantify interconversion between bidentate and monodentate binding poses. We provide a systematic determination of the relative free energy of the monodentate and bidentate structures in order to identify whether structural differences alter the nature of the methyl transfer mechanism and source of enzymatic rate enhancement. We demonstrate that the bidentate and monodentate binding modes are close in energy but separated by a 7 kcal/mol free energy barrier. Analysis of interactions in the two binding modes reveals that the driving force for monodentate catecholate orientations in classical molecular dynamics simulations is derived from stronger electrostatic stabilization afforded by alternate Mg2+ coordination with strongly charged active site carboxylates. Mixed semi-empirical-classical (SQM/MM) substrate C-O distances (2.7 Å) for the bidentate case are in excellent agreement with COMT X-ray crystal structures, as long as charge transfer between the substrates, Mg2+, and surrounding ligands is permitted. SQM/MM free energy barriers for methyl transfer from bidentate and monodentate catecholate configurations are comparable at around 21–22 kcal/mol, in good agreement with experiment (18–19 kcal/mol). Overall, the work suggests that both binding poses are viable for methyl transfer, and accurate descriptions of charge transfer and electrostatics are needed to provide balanced relative barriers when multiple binding poses are

  4. Computational Investigation of the Interplay of Substrate Positioning and Reactivity in Catechol O-Methyltransferase.

    PubMed

    Patra, Niladri; Ioannidis, Efthymios I; Kulik, Heather J

    2016-01-01

    Catechol O-methyltransferase (COMT) is a SAM- and Mg2+-dependent methyltransferase that regulates neurotransmitters through methylation. Simulations and experiments have identified divergent catecholamine substrate orientations in the COMT active site: molecular dynamics simulations have favored a monodentate coordination of catecholate substrates to the active site Mg2+, and crystal structures instead preserve bidentate coordination along with short (2.65 Å) methyl donor-acceptor distances. We carry out longer dynamics (up to 350 ns) to quantify interconversion between bidentate and monodentate binding poses. We provide a systematic determination of the relative free energy of the monodentate and bidentate structures in order to identify whether structural differences alter the nature of the methyl transfer mechanism and source of enzymatic rate enhancement. We demonstrate that the bidentate and monodentate binding modes are close in energy but separated by a 7 kcal/mol free energy barrier. Analysis of interactions in the two binding modes reveals that the driving force for monodentate catecholate orientations in classical molecular dynamics simulations is derived from stronger electrostatic stabilization afforded by alternate Mg2+ coordination with strongly charged active site carboxylates. Mixed semi-empirical-classical (SQM/MM) substrate C-O distances (2.7 Å) for the bidentate case are in excellent agreement with COMT X-ray crystal structures, as long as charge transfer between the substrates, Mg2+, and surrounding ligands is permitted. SQM/MM free energy barriers for methyl transfer from bidentate and monodentate catecholate configurations are comparable at around 21-22 kcal/mol, in good agreement with experiment (18-19 kcal/mol). Overall, the work suggests that both binding poses are viable for methyl transfer, and accurate descriptions of charge transfer and electrostatics are needed to provide balanced relative barriers when multiple binding poses are

  5. Catechol Formation and Melanization by Na+ -Dependent Azotobacter chroococcum: a Protective Mechanism for Aeroadaptation?

    PubMed Central

    Shivprasad, Shailaja; Page, William J.

    1989-01-01

    Aeroadaptive microaerophilic Azotobacter chroococcum 184 produced a cell-associated black pigment when grown at high aeration rates under nitrogen-fixing conditions. This pigment was shown to be a catechol melanin. Polyphenol oxidase activity was detected in cell extracts of cells grown for 72 h. Melanin formation was optimal in the later stages of growth, and there was no correlation between nitrogenase activity and melanization. Nitrogenase activity in strain 184 was optimal at 10% O2, and melanin formation was suppressed by O2 limitation. In the presence of charcoal, an adsorbent of toxic oxygen intermediates, and benzoic acid, a scavenger of hydroxyl radicals, melanization was inhibited. However, in the presence of copper, the intensity of pigment color increased and melanization was accelerated. Copper also eliminated catalase and peroxidase activities of the organism but still permitted aerobic growth. In the presence of low levels of iron, melanization was accelerated under high aeration rates, and under low rates of aeration, melanization was observed only at higher levels of iron. Hydroxamate-siderophore production was detectable in the presence of soluble iron under high rates of aeration but was repressed by the same levels of iron under low aeration rates. Unlike melanization and hydroxamate formation, catechol formation was observed under both low and high rates of aeration under nitrogen-fixing conditions. Catechol formation and melanization were repressed by 14 mM NH4+, at which level nitrogenase activity was also repressed. Copper reversed the repressive effect of NH4+. A role for catechol formation and melanization in aeroadaptation is proposed. PMID:16347974

  6. Melatonin as a selective estrogen enzyme modulator.

    PubMed

    Cos, S; González, A; Martínez-Campa, C; Mediavilla, M D; Alonso-González, C; Sánchez-Barceló, E J

    2008-12-01

    Melatonin exerts oncostatic effects on different kinds of tumors, especially on hormone-dependent breast cancer. The general conclusion is that melatonin, in vivo, reduces the incidence and growth of chemically-induced mammary tumors in rodents, and, in vitro, inhibits the proliferation and invasiveness of human breast cancer cells. Both studies support the hypothesis that melatonin inhibits the growth of breast cancer by interacting with estrogen-signaling pathways through three different mechanisms: (a) the indirect neuroendocrine mechanism which includes the melatonin down-regulation of the hypothalamic-pituitary-reproductive axis and the consequent reduction of circulating levels of gonadal estrogens, (b) direct melatonin actions at tumor cell level by interacting with the activation of the estrogen receptor, thus behaving as a selective estrogen receptor modulator (SERM), and (c) the regulation of the enzymes involved in the biosynthesis of estrogens in peripheral tissues, thus behaving as a selective estrogen enzyme modulator (SEEM). As melatonin reduces the activity and expression of aromatase, sulfatase and 17beta-hydroxysteroid dehydrogenase and increases the activity and expression of estrogen sulfotransferase, it may protect mammary tissue from excessive estrogenic effects. Thus, a single molecule has both SERM and SEEM properties, one of the main objectives desired for the breast antitumoral drugs. Since the inhibition of enzymes involved in the biosynthesis of estrogens is currently one of the first therapeutic strategies used against the growth of breast cancer, melatonin modulation of different enzymes involved in the synthesis of steroid hormones makes, collectively, this indolamine an interesting anticancer drug in the prevention and treatment of estrogen-dependent mammary tumors.

  7. Isolation and characterization of two novel halotolerant Catechol 2, 3-dioxygenases from a halophilic bacterial consortium

    NASA Astrophysics Data System (ADS)

    Guo, Guang; Fang, Tingting; Wang, Chongyang; Huang, Yong; Tian, Fang; Cui, Qijia; Wang, Hui

    2015-12-01

    Study of enzymes in halophiles will help to understand the mechanism of aromatic hydrocarbons degradation in saline environment. In this study, two novel catechol 2,3-dioxygenases (C23O1 and C23O2) were cloned and overexpressed from a halophilic bacterial consortium enriched from an oil-contaminated saline soil. Phylogenetic analysis indicated that the novel C23Os and their relatives formed a new branch in subfamily I.2.A of extradiol dioxygenases and the sequence differences were further analyzed by amino acid sequence alignment. Two enzymes with the halotolerant feature were active over a range of 0-30% salinity and they performed more stable at high salinity than in the absence of salt. Surface electrostatic potential and amino acids composition calculation suggested high acidic residues content, accounting for their tolerance to high salinity. Moreover, two enzymes were further characterized. The enzymes activity both increased in the presence of Fe3+, Fe2+, Cu2+ and Al3+ and showed no significant inhibition by other tested metal ions. The optimal temperatures for the C23Os were 40 °C and 60 °C and their best substrates were catechol and 4-methylcatechol respectively. As the firstly isolated and characterized catechol dioxygenases from halophiles, the two halotolerant C23Os presented novel characteristics suggesting their potential application in aromatic hydrocarbons biodegradation.

  8. Adsorptive removal of aniline by granular activated carbon from aqueous solutions with catechol and resorcinol.

    PubMed

    Suresh, S; Srivastava, V C; Mishrab, I M

    2012-01-01

    In the present paper, the removal of aniline by adsorption process onto granular activated carbon (GAC) is reported from aqueous solutions containing catechol and resorcinol separately. The Taguchi experimental design was applied to study the effect of such parameters as the initial component concentrations (C(0,i)) of two solutes (aniline and catechol or aniline and resorcinol) in the solution, temperature (T), adsorbent dosage (m) and contact time (t). The L27 orthogonal array consisting of five parameters each with three levels was used to determine the total amount of solutes adsorbed on GAC (q(tot), mmol/g) and the signal-to-noise ratio. The analysis of variance (ANOVA) was used to determine the optimum conditions. Under these conditions, the ANOVA shows that m is the most important parameter in the adsorption process. The most favourable levels of process parameters were T = 303 K, m = 10 g/l and t = 660 min for both the systems, qtot values in the confirmation experiments carried out at optimum conditions were 0.73 and 0.95 mmol/g for aniline-catechol and aniline-resorcinol systems, respectively.

  9. Secondary Organic Aerosol formation from the gas-phase reaction of catechol with ozone

    NASA Astrophysics Data System (ADS)

    Coeur-Tourneur, C.; Tomas, A.; Guilloteau, A.; Henry, F.; Ledoux, F.; Visez, N.; Riffault, V.; Wenger, J. C.; Bedjanian, Y.; Foulon, V.

    2009-04-01

    The formation of secondary organic aerosol from the gas-phase reaction of catechol (1,2-dihydroxybenzene) with ozone has been studied in two smog chambers (at the LPCA in France and at the CRAC in Ireland). Aerosol production was monitored using a scanning mobility particle sizer. The overall organic aerosol yield (Y) was determined as the ratio of the suspended aerosol mass corrected for wall losses (Mo) to the total reacted catechol concentrations, assuming a particle density of 1.4 g cm-3. Analysis of the data clearly shows that Y is a strong function of Mo and that secondary organic aerosol formation can be expressed by a one-product gas/particle partitioning absorption model. The aerosol formation is affected by the initial catechol concentration, which leads to aerosol yields ranging from 17% to 86%. The aerosol yields determined in the LPCA and CRAC smog chambers were comparable and were also in accordance with those determined in a previous study performed in EUPHORE (EUropean PHOto REactor, Spain).

  10. Catechol-initiated polyethers: multifunctional hydrophilic ligands for PEGylation and functionalization of metal oxide nanoparticles.

    PubMed

    Wilms, Valerie S; Bauer, Heiko; Tonhauser, Christine; Schilmann, Anna-Maria; Müller, Marc-Christian; Tremel, Wolfgang; Frey, Holger

    2013-01-14

    Bifunctional CA-PEG (catechol-poly(ethylene glycol)) and multifunctional CA-PEG-PGA/PEVGE (poly(glycidyl amine)/poly(ethylene glycol vinyl glycidyl ether)) ligands for the functionalization and solubilization of nanoparticles are introduced. Tunable polymers with polydispersities <1.25 and molecular weights in the range 500-7700 g mol(-1) containing a catechol moiety for conjugation to metal oxide nanoparticles were prepared. The functional PEG ligands were synthesized starting from the acetonide-protected catechol initiator 2,2-dimethyl-1,3-benzodioxole-5-propanol (CA-OH) for oxyanionic polymerization. CA-OH was used both for homopolymerization of ethylene oxide (EO) as well as copolymerization with functional epoxides N,N-diallyl glycidyl amine (DAGA), releasing primary amino groups and ethylene glycol vinyl glycidyl ether (EVGE), exhibiting a double bond for click-type reactions, to generate CA-PEG and CA-PEG-PGA/PEVGE. We demonstrate the potential of the functional ligands by binding to MnO nanoparticles, rendering the PEGylated nanoparticles highly stable in aqueous environment. Furthermore, addressability of the functional groups has been proven, for example, by coupling with fluoresceine isothiocyanate (FITC), to allow for optical monitoring of the nanoparticle fate in biological systems.

  11. Hydroxylation of phenol to catechol by Candida tropicalis: involvement of cytochrome P450.

    PubMed

    Stiborová, M; Suchá, V; Miksanová, M; Páca, J; Páca, J

    2003-06-01

    Microsomal preparations isolated from yeast Candida tropicalis (C. tropicalis) grown on three different media with or without phenol were isolated and characterized for the content of cytochrome P450 (CYP) (EC 1.14.15.1). While no CYP was detected in microsomes of C. tropicalis grown on glucose as the carbon source, evidence was obtained for the presence of the enzyme in the microsomes of C. tropicalis grown on media containing phenol. Furthermore, the activity of NADPH: CYP reductase, another enzyme of the microsomal CYP-dependent system, was markedly higher in cells grown on phenol. Microsomes of these cells oxidized phenol. The major metabolite formed from phenol by microsomes of C. tropicalis was characterized by UV/vis absorbance and mass spectroscopy as well as by the chromatographic properties on HPLC. The characteristics are identical to those of catechol. The formation of catechol was inhibited by CO, the inhibitor of CYP, and correlated with the content of cytochrome P450 in microsomes. These results, the first report showing the ring hydroxylation of phenol to catechol with the microsomal enzyme system of C. tropicalis, strongly suggest that CYP-catalyzed reactions are responsible for this hydroxylation. The data demonstrate the progress in resolving the enzymes responsible for the first step of phenol degradation by the C. tropicalis strain.

  12. Magnetic catechol-chitosan with bioinspired adhesive surface: preparation and immobilization of ω-transaminase.

    PubMed

    Ni, Kefeng; Zhou, Xu; Zhao, Li; Wang, Hualei; Ren, Yuhong; Wei, Dongzhi

    2012-01-01

    The magnetic chitosan nanocomposites have been studied intensively and been used practically in various biomedical and biological applications including enzyme immobilization. However, the loading capacity and the remained activity of immobilized enzyme based on existing approaches are not satisfied. Simpler and more effective immobilization strategies are needed. Here we report a simple catechol modified protocol for preparing a novel catechol-chitosan (CCS)-iron oxide nanoparticles (IONPs) composites carrying adhesive moieties with strong surface affinity. The ω-transaminase (ω-TA) was immobilized onto this magnetic composite via nucleophilic reactions between catechol and ω-TA. Under optimal conditions, 87.5% of the available ω-TA was immobilized on the composite, yielding an enzyme loading capacity as high as 681.7 mg/g. Furthermore, the valuation of enzyme activity showed that ω-TA immobilized on CCS-IONPs displayed enhanced pH and thermal stability compared to free enzyme. Importantly, the immobilized ω-TA retained more than 50% of its initial activity after 15 repeated reaction cycles using magnetic separation and 61.5% of its initial activity after storage at 4°C in phosphate buffered saline (PBS) for 15 days. The results suggested that such adhesive magnetic composites may provide an improved platform technology for bio-macromolecules immobilized.

  13. Reaction Kinetics of Catechol (1,2-Benzenediol) and Guaiacol (2-Methoxyphenol) with Ozone.

    PubMed

    Zein, Atallah El; Coeur, Cécile; Obeid, Emil; Lauraguais, Amélie; Fagniez, Thomas

    2015-07-01

    The kinetic reactions of 1,2-benzenediol (catechol) and 2-methoxyphenol (guaiacol) with ozone were studied in a simulation chamber (8 m(3)) under dark conditions. The rate coefficients were measured at 294 ± 2 K, atmospheric pressure and dry conditions (relative humidity, RH < 1%), except for 1,2-benzenediol where they were also measured as a function of relative humidity (RH = 1-80%). The concentrations of organic compounds were followed by a PTR-ToF-MS for a continuous monitoring of gas-phase species. The O3 rate coefficients were obtained using both the pseudo-first-order and relative rate methods. The values (in cm(3) molecule(-1) s(-1)) determined for catechol and guaiacol under dry conditions are (13.5 ± 1.1) × 10(-18) and (0.40 ± 0.31) × 10(-18), respectively. The rate coefficient of catechol was found to be independent of RH below 20% and above 60%, whereas for RH between 20% and 60% it decreases with increasing RH. The determined rate coefficients have been used to evaluate the atmospheric lifetime of each compound with respect to O3. To our knowledge, this study represents the first determination of the ozone rate coefficient with guaiacol and is also the first kinetic investigation for the influence of the relative humidity on the oxygenated aromatic ozonolysis.

  14. Versatile tuning of supramolecular hydrogels through metal complexation of oxidation-resistant catechol-inspired ligands.

    PubMed

    Menyo, Matthew S; Hawker, Craig J; Waite, J Herbert

    2013-11-21

    The mussel byssal cuticle employs DOPA-Fe(3+) complexation to provide strong, yet reversible crosslinking. Synthetic constructs employing this design motif based on catechol units are plagued by oxidation-driven degradation of the catechol units and the requirement for highly alkaline pH conditions leading to decreased performance and loss of supramolecular properties. Herein, a platform based on a 4-arm poly(ethylene glycol) hydrogel system is used to explore the utility of DOPA analogues such as the parent catechol and derivatives, 4-nitrocatechol (nCat) and 3-hydroxy-4-pyridinonone (HOPO), as structural crosslinking agents upon complexation with metal ions. HOPO moieties are found to hold particular promise, as robust gelation with Fe(3+) occurs at physiological pH and is found to be largely resistant to oxidative degradation. Gelation is also shown to be triggered by other biorelevant metal ions such as Al(3+), Ga(3+) and Cu(2+) which allows for tuning of the release and dissolution profiles with potential application as injectable delivery systems.

  15. Versatile tuning of supramolecular hydrogels through metal complexation of oxidation-resistant catechol-inspired ligands

    PubMed Central

    Menyo, Matthew S.

    2013-01-01

    The mussel byssal cuticle employs DOPA-Fe3+ complexation to provide strong, yet reversible crosslinking. Synthetic constructs employing this design motif based on catechol units are plagued by oxidation-driven degradation of the catechol units and the requirement for highly alkaline pH conditions leading to decreased performance and loss of supramolecular properties. Herein, a platform based on a 4-arm poly(ethylene glycol) hydrogel system is used to explore the utility of DOPA analogues such as the parent catechol and derivatives, 4-nitrocatechol (nCat) and 3-hydroxy-4-pyridinonone (HOPO), as structural crosslinking agents upon complexation with metal ions. HOPO moieties are found to hold particular promise, as robust gelation with Fe3+ occurs at physiological pH and is found to be largely resistant to oxidative degradation. Gelation is also shown to be triggered by other biorelevant metal ions such as Al3+, Ga3+ and Cu2+ which allows for tuning of the release and dissolution profiles with potential application as injectable delivery systems. PMID:24285981

  16. Dinuclear copper complexes with imidazole derivative ligands: a theoretical study related to catechol oxidase activity.

    PubMed

    Martínez, Ana; Membrillo, Ingrid; Ugalde-Saldívar, Victor M; Gasque, Laura

    2012-07-19

    Catechol oxidase is a very important and interesting metalloprotein. In spite of the efforts to understand the reaction mechanism of this protein, there are important questions that remain unanswered concerning the catalytic mechanism of this enzyme. In this article, dinuclear copper compounds are used as biomimetic models of catechol oxidase to study plausible reaction paths. These dinuclear copper(II) complexes have distant metal centers (of 7.5 Å approximately) and superior catalytic activity to that of many dicopper complexes with shorter Cu-Cu distances. One mononuclear copper(II) complex is also analyzed in this investigation in order to see the influence of the two metal centers in the catalytic activity. Density functional theory calculations were performed to obtain optimized structures, vertical ionization energies, vertical electron affinities, the electrodonating power (ω(-)), the electroaccepting power (ω(+)) and the energy difference of several reaction paths. The K(M) experimental results that were previously reported compare well with the electroaccepting power (ω(+)) of the copper compounds that are included in this article, indicating that this index is useful for the interpretation of the electron transfer capacity and therefore the catalytic activity. The catechol moiety coordinates to only one Cu ion, but two metal atoms are needed in order to have a good electron acceptor capacity of the biomimetic models.

  17. Magnetic catechol-chitosan with bioinspired adhesive surface: preparation and immobilization of ω-transaminase.

    PubMed

    Ni, Kefeng; Zhou, Xu; Zhao, Li; Wang, Hualei; Ren, Yuhong; Wei, Dongzhi

    2012-01-01

    The magnetic chitosan nanocomposites have been studied intensively and been used practically in various biomedical and biological applications including enzyme immobilization. However, the loading capacity and the remained activity of immobilized enzyme based on existing approaches are not satisfied. Simpler and more effective immobilization strategies are needed. Here we report a simple catechol modified protocol for preparing a novel catechol-chitosan (CCS)-iron oxide nanoparticles (IONPs) composites carrying adhesive moieties with strong surface affinity. The ω-transaminase (ω-TA) was immobilized onto this magnetic composite via nucleophilic reactions between catechol and ω-TA. Under optimal conditions, 87.5% of the available ω-TA was immobilized on the composite, yielding an enzyme loading capacity as high as 681.7 mg/g. Furthermore, the valuation of enzyme activity showed that ω-TA immobilized on CCS-IONPs displayed enhanced pH and thermal stability compared to free enzyme. Importantly, the immobilized ω-TA retained more than 50% of its initial activity after 15 repeated reaction cycles using magnetic separation and 61.5% of its initial activity after storage at 4°C in phosphate buffered saline (PBS) for 15 days. The results suggested that such adhesive magnetic composites may provide an improved platform technology for bio-macromolecules immobilized. PMID:22815930

  18. Isolation and characterization of two novel halotolerant Catechol 2, 3-dioxygenases from a halophilic bacterial consortium.

    PubMed

    Guo, Guang; Fang, Tingting; Wang, Chongyang; Huang, Yong; Tian, Fang; Cui, Qijia; Wang, Hui

    2015-01-01

    Study of enzymes in halophiles will help to understand the mechanism of aromatic hydrocarbons degradation in saline environment. In this study, two novel catechol 2,3-dioxygenases (C23O1 and C23O2) were cloned and overexpressed from a halophilic bacterial consortium enriched from an oil-contaminated saline soil. Phylogenetic analysis indicated that the novel C23Os and their relatives formed a new branch in subfamily I.2.A of extradiol dioxygenases and the sequence differences were further analyzed by amino acid sequence alignment. Two enzymes with the halotolerant feature were active over a range of 0-30% salinity and they performed more stable at high salinity than in the absence of salt. Surface electrostatic potential and amino acids composition calculation suggested high acidic residues content, accounting for their tolerance to high salinity. Moreover, two enzymes were further characterized. The enzymes activity both increased in the presence of Fe(3+), Fe(2+), Cu(2+) and Al(3+) and showed no significant inhibition by other tested metal ions. The optimal temperatures for the C23Os were 40 °C and 60 °C and their best substrates were catechol and 4-methylcatechol respectively. As the firstly isolated and characterized catechol dioxygenases from halophiles, the two halotolerant C23Os presented novel characteristics suggesting their potential application in aromatic hydrocarbons biodegradation. PMID:26621792

  19. Isolation and characterization of two novel halotolerant Catechol 2, 3-dioxygenases from a halophilic bacterial consortium

    PubMed Central

    Guo, Guang; Fang, Tingting; Wang, Chongyang; Huang, Yong; Tian, Fang; Cui, Qijia; Wang, Hui

    2015-01-01

    Study of enzymes in halophiles will help to understand the mechanism of aromatic hydrocarbons degradation in saline environment. In this study, two novel catechol 2,3-dioxygenases (C23O1 and C23O2) were cloned and overexpressed from a halophilic bacterial consortium enriched from an oil-contaminated saline soil. Phylogenetic analysis indicated that the novel C23Os and their relatives formed a new branch in subfamily I.2.A of extradiol dioxygenases and the sequence differences were further analyzed by amino acid sequence alignment. Two enzymes with the halotolerant feature were active over a range of 0–30% salinity and they performed more stable at high salinity than in the absence of salt. Surface electrostatic potential and amino acids composition calculation suggested high acidic residues content, accounting for their tolerance to high salinity. Moreover, two enzymes were further characterized. The enzymes activity both increased in the presence of Fe3+, Fe2+, Cu2+ and Al3+ and showed no significant inhibition by other tested metal ions. The optimal temperatures for the C23Os were 40 °C and 60 °C and their best substrates were catechol and 4-methylcatechol respectively. As the firstly isolated and characterized catechol dioxygenases from halophiles, the two halotolerant C23Os presented novel characteristics suggesting their potential application in aromatic hydrocarbons biodegradation. PMID:26621792

  20. Biocidal properties of metal oxide nanoparticles and their halogen adducts

    NASA Astrophysics Data System (ADS)

    Haggstrom, Johanna A.; Klabunde, Kenneth J.; Marchin, George L.

    2010-03-01

    Nanosized metal oxide halogen adducts possess high surface reactivities due to their unique surface morphologies. These adducts have been used as reactive materials against vegetative cells, such as Escherichia coli as well as bacterial endospores, including Bacillus subtilis and Bacillus anthracis (Δ Sterne strain). Here we report high biocidal activities against gram-positive bacteria, gram-negative bacteria, and endospores. The procedure consists of a membrane method. Transmission electron micrographs are used to compare nanoparticle-treated and untreated cells and spores. It is proposed that the abrasive character of the particles, the oxidative power of the halogens/interhalogens, and the electrostatic attraction between the metal oxides and the biological material are responsible for high biocidal activities. While some activity was demonstrated, bacterial endospores were more resistant to nanoparticle treatment than the vegetative bacteria.

  1. 2' and 3' Carboranyl uridines and their diethyl ether adducts

    DOEpatents

    Soloway, Albert H.; Barth, Rolf F.; Anisuzzaman, Abul K.; Alam, Fazlul; Tjarks, Werner

    1992-01-01

    There is disclosed a process for preparing carboranyl uridine nucleoside compounds and their diethyl ether adducts, which exhibit a tenfold increase in boron content over prior art boron containing nucleoside compounds. Said carboranyl uridine nucleoside compounds exhibit enhanced lipophilicity and hydrophilic properties adequate to enable solvation in aqueous media for subsequent incorporation of said compounds in methods for boron neutron capture therapy in mammalian tumor cells.

  2. Dispersant additives derived from lactone modified amido-amine adducts

    SciTech Connect

    Gutierrez, A.; Lundberg, R.D.

    1990-10-16

    This patent describes a lactone modified dispersant additive. It comprises one adduct of a polyolefin of 300 to 10,000 number average molecular weight substituted with at least 0.8 (e.g., from about 1 to 4) dicarboxylic acid producing moieties (preferably acid or anhydride moieties) per polyolefin molecule, an amido-amine or thioamido-amine characterized by being a reaction product of at least a polyamine and an alpha, beta-unsaturated compound.

  3. Protein tyrosine adduct in humans self-poisoned by chlorpyrifos

    SciTech Connect

    Li, Bin; Eyer, Peter; Eddleston, Michael; Jiang, Wei; Schopfer, Lawrence M.; Lockridge, Oksana

    2013-06-15

    Studies of human cases of self-inflicted poisoning suggest that chlorpyrifos oxon reacts not only with acetylcholinesterase and butyrylcholinesterase but also with other blood proteins. A favored candidate is albumin because in vitro and animal studies have identified tyrosine 411 of albumin as a site covalently modified by organophosphorus poisons. Our goal was to test this proposal in humans by determining whether plasma from humans poisoned by chlorpyrifos has adducts on tyrosine. Plasma samples from 5 self-poisoned humans were drawn at various time intervals after ingestion of chlorpyrifos for a total of 34 samples. All 34 samples were analyzed for plasma levels of chlorpyrifos and chlorpyrifos oxon (CPO) as a function of time post-ingestion. Eleven samples were analyzed for the presence of diethoxyphosphorylated tyrosine by mass spectrometry. Six samples yielded diethoxyphosphorylated tyrosine in pronase digests. Blood collected as late as 5 days after chlorpyrifos ingestion was positive for CPO-tyrosine, consistent with the 20-day half-life of albumin. High plasma CPO levels did not predict detectable levels of CPO-tyrosine. CPO-tyrosine was identified in pralidoxime treated patients as well as in patients not treated with pralidoxime, indicating that pralidoxime does not reverse CPO binding to tyrosine in humans. Plasma butyrylcholinesterase was a more sensitive biomarker of exposure than adducts on tyrosine. In conclusion, chlorpyrifos oxon makes a stable covalent adduct on the tyrosine residue of blood proteins in humans who ingested chlorpyrifos. - Highlights: • Chlorpyrifos-poisoned patients have adducts on protein tyrosine. • Diethoxyphosphate-tyrosine does not lose an alkyl group. • Proteins in addition to AChE and BChE are modified by organophosphates.

  4. Ion Pairs or Neutral Molecule Adducts? Cooperativity in Hydrogen Bonding

    ERIC Educational Resources Information Center

    DeKock, Roger L.; Schipper, Laura A.; Dykhouse, Stephanie C.; Heeringa, Lee P.; Brandsen, Benjamin M.

    2009-01-01

    We performed theoretical studies on the systems NH[subscript 3] times HF times mH[subscript 2]O, NH[subscript 3] times HCl times mH[subscript 2]O, with m = 0, 1, 2, and 6. The molecules with m = 0 form hydrogen-bonded adducts with little tendency to form an ion-pair structure. The molecule NH[subscript 3] times HCl times H[subscript 2]O cannot be…

  5. A structurally-characterized NbCl5-NHC adduct.

    PubMed

    Bortoluzzi, Marco; Ferretti, Eleonora; Marchetti, Fabio; Pampaloni, Guido; Zacchini, Stefano

    2014-05-01

    The selective reactions of niobium pentachloride with two bulky NHC carbenes afforded NbCl5(NHC) complexes, bearing the highest oxidation state ever found for a metal centre in a transition metal halide-NHC adduct. The X-ray structure of 2a is the first one reported for a monodentate NHC-niobium species, and exhibits an abnormally long Nb-C bond. PMID:24658260

  6. Toxicological significance of DNA adducts: summary of discussions with an expert panel.

    PubMed

    Nestmann, E R; Bryant, D W; Carr, C J

    1996-08-01

    A workshop was held to discuss the uses of data on DNA adduct measurement in humans and in experimental systems in vitro and in vivo. The discussions focused principally on the understanding of the toxicological significance of DNA adducts as provided by information from animal models. An Expert Panel concluded that human DNA adduct data have utility in several aspects of risk assessment. The presence and amount of specific adducts that can be correlated with a chemical exposure are relevant for hazard identification and risk evaluation. Data from experimental systems have established dose-response relationships between the level of adducts and exposure, but these remain complex and depend on metabolic fate. Although structure-activity relationships have been useful retrospectively to explain the DNA-reactive nature of some chemicals or classes of chemicals, there are currently no means outside the laboratory to specifically predict the adduct-producing potency of a compound. Analysis of DNA adducts in tissues of laboratory animals and humans has revealed sensitive subpopulations, a finding that has important relevance for human risk assessment. Adduct analysis may be one of the best tools available to characterize exposures to DNA from complex mixtures for purposes of epidemiological investigation. Consensus statements were developed based on presentations by R. Gupta, W. Lutz, R. Nath, and B. Singer [see Regul. Toxicol. Pharmacol. 23(1), 1996] and subsequent discussions. First, rigorous scientific criteria should be met for the detection and characterization of specific DNA adducts in vitro and in target tissues in vivo. Second, the use of adduct data in risk extrapolation has the greatest value when there is characterization of adduct structure, an understanding of the role of repair in DNA adduct removal, and demonstration of biological relevance for each adduct. Third, the detection of DNA adducts in a tissue does not necessarily indicate a specific

  7. Estrogen or estrogen receptor agonist inhibits lipopolysaccharide induced microglial activation and death.

    PubMed

    Smith, Joshua A; Das, Arabinda; Butler, Jonathan T; Ray, Swapan K; Banik, Naren L

    2011-09-01

    Inflammation is an important pathogenic mechanism in many neurodegenerative disorders. Activated microglia play a pivotal role in releasing pro-inflammatory factors including interleukin-1 (IL-1), tumor necrosis factor-α (TNF-α), and cyclooxygenase-2 (COX-2) for inducing inflammation. While microglia mediated inflammation is essential in maintaining CNS homeostasis, chronic inflammation results in activation of proteases for cell death. Here, we examined the effect of PPT (estrogen receptor α agonist), DPN (estrogen receptor β agonist), and estrogen on rat primary microglia following exposure to lipopolysaccharide (LPS). Exposure of microglia to LPS (200 ng/ml) for 24 h induced cell death. After LPS toxicity for 15 min, microglia were treated with 25 nM PPT, 25 nM DPN, or 100 nM estrogen that prevented cell death by attenuating the release of IL-1α, IL-1β, TNF-α, and COX-2. Treatment of cells with 100 nM fulvestrant (estrogen receptor antagonist) prior to addition of PPT, DPN, or estrogen significantly decreased their ability to prevent cell death, indicating involvement of estrogen receptor (ER) in providing PPT, DPN, or estrogen mediated cytoprotection. Reverse transcriptase polymerase chain reaction (RT-PCR) analyses showed alterations in mRNA expression of Bax, Bcl-2, calpain, and calpastatin during apoptosis. We also examined mRNA expression of ERβ and ERα following exposure of microglia to LPS and subsequent treatment with PPT, DPN, or estrogen. We found that estrogen or estrogen receptor agonists upregulated expression of ERs. Overall, results indicate that estrogen receptor agonist or estrogen uses a receptor mediated pathway to protect microglia from LPS toxicity.

  8. Analysis of protein adduction kinetics by quantitative mass spectrometry: competing adduction reactions of glutathione-S-transferase P1-1 with electrophiles.

    PubMed

    Orton, Christopher R; Liebler, Daniel C

    2007-06-30

    Defining the mechanisms and consequences of protein adduction is crucial to understanding the toxicity of reactive electrophiles. Application of tandem mass spectrometry and data analysis algorithms enables detection and mapping of chemical adducts at the level of amino acid sequence. Nevertheless, detection of adducts does not indicate relative reactivity of different sites. Here, we describe a method to measure the kinetics of competing adduction reactions at different sites on the same protein. Adducts are formed by electrophiles at Cys14 and Cys47 on the metabolic enzyme glutathione-S-transferase P1-1 and modification is accompanied by a loss of enzymatic activity. Relative quantitation of protein adducts was done by tagging N-termini of peptide digests with isotopically labeled phenyl isocyanate and tracking the ratio of light-tagged peptide adducts to heavy-tagged reference samples in liquid chromatography-tandem mass spectrometry analyses using a multiple reaction monitoring method. This approach was used to measure rate constants for adduction at both positions with two different model electrophiles, N-iodoacetyl-N-biotinylhexylenediamine and 1-biotinamido-4-(4'-[maleimidoethyl-cyclohexane]-carboxamido)butane. The results indicate that Cys47 was approximately two- to three-fold more reactive toward both electrophiles than was Cys14. This result was consistent with the relative reactivity of these electrophiles in a complex proteome system and with previously reported trends in reactivity of these sites. Kinetic analyses of protein modification reactions provide a means of evaluating the selectivity of reactive mediators of chemical toxicity.

  9. Tunable degradation of maleimide-thiol adducts in reducing environments

    PubMed Central

    Baldwin, Aaron D.; Kiick, Kristi L.

    2011-01-01

    Addition chemistries are widely used in preparing biological conjugates, and in particular, maleimide-thiol adducts have been widely employed. Here we show that the resulting succinimide thioether formed by a Michael type addition of a thiol to N-ethylmaleimide (NEM), generally accepted as stable, can in fact undergo retro and exchange reactions in the presence of other thiol compounds at physiological pH and temperature, offering a novel strategy for controlled release. Model studies (1H NMR, HPLC) of NEM conjugated to 4-mercaptophenylacetic acid (MPA), N-acetylcysteine, or 3-mercaptopropionic acid (MP) incubated with glutathione showed half lives of conversion from 20–80 hrs, with extents of conversion from 20–90% for MPA and N-acetylcysteine conjugates. Ring-opened the resultant succinimide thioether as well as any MP adduct did not show retro and exchange reactions. The kinetics of the retro reactions can be modulated by the Michael donor’s reactivity; therefore the degradation of maleimide-thiol adducts could be tuned for controlled release of drugs or degradation of materials at timescales different than those currently possible via disulfide-mediated release. Such approaches may find a new niche for controlled release in reducing environments relevant in chemotherapy and sub-cellular trafficking. PMID:21863904

  10. Detection and characterization of cyclic hydroxylamine adducts by mass spectrometry.

    PubMed

    Reis, Ana; Domingues, Maria R M; Amado, Francisco M L; Oliveira, M Manuel; Domingues, Pedro

    2008-05-01

    Two cyclic hydroxylamines (cHA) bearing pyrrolidine (CPH) and piperidine moieties (TMTH) were evaluated to trap hydroxyl, peptide and phospholipid free radicals using mass spectrometry for their detection. The cHA ionized as [M+H](+) ions, showing higher relative abundances when compared to the DMPO, probably due to higher ionization efficiency. In the presence of hydroxyl radicals, both cHA generated new ions that could be attributed to loss of (*)H and (*)CH(3), most likely deriving from decomposition reactions of the nitroxide spin adduct. Addition of cHA to Leucine-enkephalin and palmitoyl-lineloyl-glycerophosphatidylcholine free radicals promoted the formation of cHA biomolecule adducts, which were confirmed by MS/MS data. Results suggest that the cHA are not suitable for hydroxyl radical trapping but can be used for trapping biomolecule radicals, having the advantage, over the most used cyclic nitrones, of being water soluble. The biomolecule adducts identified by MS are ESR silent, evidencing the importance of MS detection.

  11. Thermal stability of DNA adducts induced by cyanomorpholinoadriamycin in vitro.

    PubMed Central

    Cullinane, C; Phillips, D R

    1993-01-01

    The Adriamycin derivative, cyanomorpholinoadriamycin (CMA) was reacted with DNA in vitro to form apparent interstrand crosslinks. The extent of interstrand crosslink formation was monitored by a gel electrophoresis assay and maximal crosslinking of DNA was observed within 1 hr with 5 microM of drug. The interstrand crosslinks were heat labile, with a midpoint melting temperature of 70 degrees C (10 min exposure to heat) in 45% formamide. When CMA-induced adducts were detected as blockages of lambda-exonuclease, 12 blockage sites were observed with 8 being prior to 5'-GG sequences, one prior to 5'-CC, one prior to 5'-GC and 2 at unresolved combinations of these sequences. These exonuclease-detected blockages reveal the same sites of CMA-induced crosslinking as detected by in vitro transcription footprinting and primer-extension blockages on single strand DNA, where the blockages at 5'-GG and 5'-CC were identified as sites of intrastrand crosslinking and the 5'-GC blockage as a probable site of interstrand crosslinking. The thermal stability of both types of crosslink (10 min exposure to heat) ranged from 63-70 degrees C at individual sites. High levels of adduct were detected with poly (dG-dC) but not with poly (dI-dC). These results suggest adduct formation involving an aminal linkage between the 3 position of the morpholino moiety and N2 of guanine. Images PMID:8493102

  12. Analysis of cytogenetic effects and DNA adduct formation induced by safrole in Chinese hamster lung cells.

    PubMed

    Daimon, H; Sawada, S; Asakura, S; Sagami, F

    1997-01-01

    Safrole (1-allyl-3,4-methylenedioxybenzene) was tested for its ability to induce sister chromatid exchanges (SCEs) and chromosomal aberrations (CAs) and to form DNA adducts in Chinese hamster lung (CHL) cells, in order to investigate the relationship between cytogenetic effects and DNA adduct formation under the same treatment conditions. The cells were treated with 0.025-0.2 mg/ml safrole in the presence or absence of rat liver postmitochondrial supernatant fraction (S9). Safrole induced significant SCEs and CAs dose-dependently in the presence of S9. SCEs ranged in number from 15.6 to 21.1 SCEs/cell and CAs were observed in 4-37% of cells. Using the 32P-postlabeling assay, two major and two minor safrole-DNA adducts were detected in DNA digests obtained from CHL cells in the presence of S9. The levels of total DNA adducts ranged from 1.3 to 22.8 adducts/10(7) nucleotides. The two major adducts were shown to be guanine derivatives since these adducts comigrated on polyethylenimine plates with the adducts produced by the reaction of safrole with 2'-deoxyguanosine 3'-monophosphate. A correlation was seen between DNA adducts and SCEs or CAs. Neither induction of SCEs and CAs nor formation of DNA adducts was observed in the absence of S9. These findings suggest that SCEs and CAs induced by safrole result from covalent DNA modification metabolically activated by S9 in cultured cells.

  13. Effect of phytochemical intervention on dibenzo[a,l]pyrene-induced DNA adduct formation

    PubMed Central

    Russell, Gilandra K.; Gupta, Ramesh C.; Vadhanam, Manicka V.

    2015-01-01

    Dibenzo[a,l]pyrene (DBP) has been found to be the most potent carcinogen of the polycyclic aromatic hydrocarbons (PAHs). Primary sources for DBP in the environment are combustion of wood and coal burning, gasoline and diesel exhaust, and tires. Given the likelihood of environmental exposure to DBP and strong experimental evidence of its potency, it is likely to contribute to lung cancer development. Intervention with compounds of natural origin (“phytochemicals”) is considered an effective means to prevent cancer development and favorably modulate the underlying mechanisms, including DNA adduct formation. In this study, several agents have been identified that inhibit environmental carcinogen-induced DNA adduct formation using a cell-free microsomal system. Of the ten agents tested, resveratrol (648 ± 26 adducts/109 nucleotides), oltipraz (1007 ± 348 adducts/109 nucleotides), delphinidin (1252 ± 142 adducts/109 nucleotides), tanshinone I (1981 ± 213 adducts/109 nucleotides), tanshinone IIA (2606 ± 478 adducts/109 nucleotides) and diindoylmethane (3643 ± 469 adducts/109 nucleotides) were the most effective compared to vehicle treatment (14,062 ± 1097 adducts/109 nucleotides). DBP is metabolized by phase I metabolizing enzymes CYP1A1, CYP1A2, and CYP1B1. DBP-induced DNA adducts can be inhibited by several mechanisms. We found that all the test agents inhibited DNA adducts by inhibiting one or more of these enzymes. Oltipraz inhibited DNA adducts entirely by inhibiting the CYP450s, while resveratrol and delphinidin inhibited DNA adducts by also interacting directly with the carcinogenic metabolite, anti-dibenzo(a,l)pyrene-11,12-dihydrodiol-13,14-epoxide. PMID:25794985

  14. Estrogen

    MedlinePlus

    ... you are allergic to aspirin or tartrazine (a food color additive). Ask your pharmacist or check the manufacturer's patient ... this medication.If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting ...

  15. Estrogens from sewage in coastal marine environments.

    PubMed Central

    Atkinson, Shannon; Atkinson, Marlin J; Tarrant, Ann M

    2003-01-01

    Estrogens are ancient molecules that act as hormones in vertebrates and are biologically active in diverse animal phyla. Sewage contains natural and synthetic estrogens that are detectable in streams, rivers, and lakes. There are no studies reporting the distribution of steroidal estrogens in marine environments. We measured estrogens in sewage, injection-well water, and coastal tropical and offshore tropical water in the Pacific Ocean, western Atlantic Ocean, and Caribbean Sea. Concentrations of unconjugated estrone ranged from undetectable (< 40 pg/L) in the open ocean to nearly 2,000 pg/L in Key West, Florida, and Rehoboth Bay, Delaware (USA); estrone concentrations were highest near sources of sewage. Enzymatic hydrolysis of steroid conjugates in seawater samples indicated that polar conjugates comprise one-half to two-thirds of "total estrone" (unconjugated plus conjugated) in Hawaiian coastal samples. Adsorption to basalt gravel and carbonate sand was less than 20% per week and indicates that estrogens can easily leach into the marine environment from septic fields and high-estrogen groundwater. Of 20 sites (n = 129 samples), the mean values from 12 sites were above the threshold concentration for uptake into coral, indicating that there is a net uptake of anthropogenic steroidal estrogen into these environments, with unknown impacts. PMID:12676611

  16. Estrogen Receptors, the Hippocampus, and Memory

    PubMed Central

    Bean, Linda A.; Ianov, Lara; Foster, Thomas C.

    2015-01-01

    Estradiol effects on memory depend on hormone levels and the interaction of different estrogen receptors within neural circuits. Estradiol induces gene transcription and rapid membrane signaling mediated by estrogen receptor-alpha (ERα), estrogen receptor-beta (ERβ), and a recently characterized G-protein coupled estrogen receptor, each with distinct distributions and ability to influence estradiol-dependent signaling. Investigations using receptor specific agonists suggest that all three receptors rapidly activate kinase-signaling and have complex dose-dependent influences on memory. Research employing receptor knockout mice demonstrate that ERα maintains transcription and memory as estradiol levels decline. This work indicates a regulatory role of ERβ in transcription and cognition, which depends on estradiol levels and the function of ERα. The regulatory role of ERβ is due in part to ERβ acting as a negative regulator of ERα-mediated transcription. Vector-mediated expression of estrogen receptors in the hippocampus provides an innovative research approach and suggests that memory depends on the relative expression of ERα and ERβ interacting with estradiol levels. Notably, the ability of estradiol to improve cognition declines with advanced age along with decreased expression of estrogen receptors. Thus, it will be important for future research to determine the mechanisms that regulate estrogen receptor expression during aging. PMID:24510074

  17. Estrogens from sewage in coastal marine environments.

    PubMed

    Atkinson, Shannon; Atkinson, Marlin J; Tarrant, Ann M

    2003-04-01

    Estrogens are ancient molecules that act as hormones in vertebrates and are biologically active in diverse animal phyla. Sewage contains natural and synthetic estrogens that are detectable in streams, rivers, and lakes. There are no studies reporting the distribution of steroidal estrogens in marine environments. We measured estrogens in sewage, injection-well water, and coastal tropical and offshore tropical water in the Pacific Ocean, western Atlantic Ocean, and Caribbean Sea. Concentrations of unconjugated estrone ranged from undetectable (< 40 pg/L) in the open ocean to nearly 2,000 pg/L in Key West, Florida, and Rehoboth Bay, Delaware (USA); estrone concentrations were highest near sources of sewage. Enzymatic hydrolysis of steroid conjugates in seawater samples indicated that polar conjugates comprise one-half to two-thirds of "total estrone" (unconjugated plus conjugated) in Hawaiian coastal samples. Adsorption to basalt gravel and carbonate sand was less than 20% per week and indicates that estrogens can easily leach into the marine environment from septic fields and high-estrogen groundwater. Of 20 sites (n = 129 samples), the mean values from 12 sites were above the threshold concentration for uptake into coral, indicating that there is a net uptake of anthropogenic steroidal estrogen into these environments, with unknown impacts. PMID:12676611

  18. The molecular etiology of breast cancer: Evidence from biomarkers of risk

    PubMed Central

    Gaikwad, Nilesh W.; Yang, Li; Muti, Paola; Meza, Jane L.; Pruthi, Sandhya; Ingle, James N.; Rogan, Eleanor G.; Cavalieri, Ercole L.

    2015-01-01

    Estrogens can become endogenous carcinogens via formation of catechol estrogen quinones, which react with DNA to form specific depurinating estrogen-DNA adducts. The mutations resulting from these adducts can lead to cell transformation and the initiation of breast cancer. Estrogen metabolites, conjugates and depurinating DNA adducts in urine samples from 46 healthy control women, 12 high-risk women and 17 women with breast cancer were analyzed. The estrogen metabolites, conjugates and depurinating DNA adducts were identified and quantified by using ultra-performance liquid chromatography/tandem mass spectrometry. The levels of the ratios of depurinating DNA adducts to their respective estrogen metabolites and conjugates were significantly higher in high-risk women (p < 0.001) and women with breast cancer (p < 0.001) than in control subjects. The high-risk and breast cancer groups were not significantly different (p = 0.62). After adjusting for patient characteristics, these ratios were still significantly associated with health status. Thus, the depurinating estrogen-DNA adducts are possible biomarkers for early detection of breast cancer risk and response to preventive treatment. PMID:18098283

  19. Bulky DNA adducts, 4-aminobiphenyl-haemoglobin adducts and diet in the European Prospective Investigation into Cancer and Nutrition (EPIC) prospective study.

    PubMed

    Peluso, Marco; Airoldi, Luisa; Munnia, Armelle; Colombi, Alessandro; Veglia, Fabrizio; Autrup, Herman; Dunning, Alison; Garte, Seymour; Gormally, Emmanuelle; Malaveille, Christian; Matullo, Giuseppe; Overvad, Kim; Raaschou-Nielsen, Ole; Clavel-Chapelon, Francoise; Linseisen, Jacob; Boeing, Heiner; Trichopoulou, Antonia; Palli, Domenico; Krogh, Vittorio; Tumino, Rosario; Panico, Salvatore; Bueno-De-Mesquita, Bas H; Peeters, Petra H; Kumle, Merethe; Agudo, Antonio; Martinez, Carmen; Dorronsoro, Miren; Barricarte, Aurelio; Tormo, Marìa Jose; Quiros, José Ramón; Berglund, Goran; Jarvholm, Bengt; Day, Nicholas E; Key, Timothy J; Saracci, Rodolfo; Kaaks, Rudolf; Riboli, Elio; Bingham, Shelia; Vineis, Paolo

    2008-09-01

    In contrast to some extensively examined food mutagens, for example, aflatoxins, N-nitrosamines and heterocyclic amines, some other food contaminants, in particular polycyclic aromatic hydrocarbons (PAH) and other aromatic compounds, have received less attention. Therefore, exploring the relationships between dietary habits and the levels of biomarkers related to exposure to aromatic compounds is highly relevant. We have investigated in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort the association between dietary items (food groups and nutrients) and aromatic DNA adducts and 4-aminobiphenyl-Hb adducts. Both types of adducts are biomarkers of carcinogen exposure and possibly of cancer risk, and were measured, respectively, in leucocytes and erythrocytes of 1086 (DNA adducts) and 190 (Hb adducts) non-smokers. An inverse, statistically significant, association has been found between DNA adduct levels and dietary fibre intake (P = 0.02), vitamin E (P = 0.04) and alcohol (P = 0.03) but not with other nutrients or food groups. Also, an inverse association between fibre and fruit intake, and BMI and 4-aminobiphenyl-Hb adducts (P = 0.03, 0.04, and 0.03 respectively) was observed. After multivariate regression analysis these inverse correlations remained statistically significant, except for the correlation adducts v. fruit intake. The present study suggests that fibre intake in the usual range can modify the level of DNA or Hb aromatic adducts, but such role seems to be quantitatively modest. Fibres could reduce the formation of DNA adducts in different manners, by diluting potential food mutagens and carcinogens in the gastrointestinal tract, by speeding their transit through the colon and by binding carcinogenic substances.

  20. Expression of estrogenicity genes in a lineage cell culture model of human breast cancer progression.

    PubMed

    Fu, Jiaqi; Weise, Amy M; Falany, Josie L; Falany, Charles N; Thibodeau, Bryan J; Miller, Fred R; Kocarek, Thomas A; Runge-Morris, Melissa

    2010-02-01

    TaqMan Gene Expression assays were used to profile the mRNA expression of estrogen receptor (ERalpha and ERbeta) and estrogen metabolism enzymes including cytosolic sulfotransferases (SULT1E1, SULT1A1, SULT2A1, and SULT2B1), steroid sulfatase (STS), aromatase (CYP19), 17beta-hydroxysteroid dehydrogenases (17betaHSD1 and 2), CYP1B1, and catechol-O-methyltransferase (COMT) in an MCF10A-derived lineage cell culture model for basal-like human breast cancer progression and in ERalpha-positive luminal MCF7 breast cancer cells. Low levels of ERalpha and ERbeta mRNA were present in MCF10A-derived cell lines. SULT1E1 mRNA was more abundant in confluent relative to subconfluent MCF10A cells, a non-tumorigenic proliferative breast disease cell line. SULT1E1 was also expressed in preneoplastic MCF10AT1 and MCF10AT1K.cl2 cells, but was markedly repressed in neoplastic MCF10A-derived cell lines as well as in MCF7 cells. Steroid-metabolizing enzymes SULT1A1 and SULT2B1 were only expressed in MCF7 cells. STS and COMT were widely detected across cell lines. Pro-estrogenic 17betaHSD1 mRNA was most abundant in neoplastic MCF10CA1a and MCF10DCIS.com cells, while 17betaHSD2 mRNA was more prominent in parental MCF10A cells. CYP1B1 mRNA was most abundant in MCF7 cells. Treatment with the histone deacetylase inhibitor trichostatin A (TSA) induced SULT1E1 and CYP19 mRNA but suppressed CYP1B1, STS, COMT, 17betaHSD1, and 17betaHSD2 mRNA in MCF10A lineage cell lines. In MCF7 cells, TSA treatment suppressed ERalpha, CYP1B1, STS, COMT, SULT1A1, and SULT2B1 but induced ERbeta, CYP19 and SULT2A1 mRNA expression. The results indicate that relative to the MCF7 breast cancer cell line, key determinants of breast estrogen metabolism are differentially regulated in the MCF10A-derived lineage model for breast cancer progression.

  1. Polymer-supported sulfonated catechol and linear catechol amide ligands and their use in selective metal ion removal recovery from aqueous solutions

    DOEpatents

    Fish, Richard H.

    1998-01-01

    The present invention concerns the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis-catechol linear amide (PS-2-6-LICAMS) and sulfonated 3,3-linear tris-catechol amide (PS-3,3-LICAMS) ligands, which chemically bond to modified 6% crosslinked macroporous polystyrene-divinylbenzene beads (PS-DVB). These polymers are useful for the for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe.sup.3+ ion selectivity shown for PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu.sup.2+, Zn.sup.2+, Mn.sup.2+, Ni.sup.2+, Mg.sup.2+, Al.sup.3+, and Cr.sup.3+ ions at pH 1-3. Further, the metal ion selectivity is changed at higher pH values in the absence of Fe.sup.3+ (for example, Hg.sup.2+ at pH 3). The rates of selective removal and recovery of the trivalent metal ions, e.g. Fe.sup.3+ Al.sup.3+ ion etc. with the PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads used determined are useful as well as equilibrium selectivity coefficient (K.sub.m) values for all metal competition studies. The chelate effect for the predisposed octahedral PS-3,3-LICAMS polymer pendant ligand is the reason that this ligand has a more pronounced selectivity for Fe.sup.3+ ion in comparison to the PS-CATS polymer beads. The predisposed square planar PS-2,6-LICAMS series of polymer pendant ligands are more selective to divalent metal ions Cu.sup.2+, Zn.sup.2+, Mn.sup.2+, Ni.sup.2+, and Mg.sup.2+, than either PS-CATS or PS-3,3-LICAMS. However, Fe.sup.3+ ion still dominates in competition with other divalent and trivalent metal ions. In the absence of Fe.sup.3+, the polymer ligand is selective for Al.sup.3+, Cu.sup.2+ or Hg.sup.2+. The changing of the cavity size from two CH.sub.2 groups to six CH.sub.2 groups in the PS-2-6-LICAMS polymer pendant ligand series does not effect the order of metal ion

  2. Polymer-supported sulfonated catechol and linear catechol amide ligands and their use in selective metal ion removal and recovery from aqueous solutions

    DOEpatents

    Fish, Richard H.

    1997-01-01

    The present invention concerns the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis-catechol linear amide (PS-2-6-LICAMS) and sulfonated 3,3-linear tris-catechol amide (PS-3,3-LICAMS) ligands, which chemically bond to modified 6% crosslinked macroporous polystyrene-divinylbenzene beads (PS-DVB). These polymers are useful for the for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe.sup.3+ ion selectivity shown for PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu.sup.2+, Zn.sup.2+, Mn.sup.2+, Ni.sup.2+,Mg.sup.2+, Al.sup.3+, and Cr.sup.3+ ions at pH 1-3. Further, the metal ion selectivity is changed at higher pH values in the absence of Fe.sup.3+ (for example, Hg.sup.2+ at pH 3). The rates of selective removal and recovery of the trivalent metal ions, e.g. Fe.sup.3+ Al.sup.3+ ion etc. with the PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads use determined are useful as well as equilibrium selectivity coefficient (K.sub.m) values for all metal competition studies. The chelate effect for the predisposed octahedral PS-3,3-LICAMS polymer pendant ligand is the reason that this ligand has a more pronounced selectivity for Fe.sup.3+ ion in comparison to the PS-CATS polymer beads. The predisposed square planar PS-2-6-Mn.sup.2+, Ni.sup.2+, and Mg.sup.2+, than either PS-CATS or PS-3,3-LICAMS. However, Fe.sup.3+ ion still dominates in competition with other divalent and trivalent metal ions. In the absence of Fe.sup.3+, the polymer ligand is selective for Al.sup.3+, Cu.sup.2+ or Hg.sup.2+. The changing of the cavity size from two CH.sub.2 groups to six CH.sub.2 groups in the PS-2-6-LICAMS polymer pendant ligand series does not effect the order of metal ion selectivity.

  3. Polymer-supported sulfonated catechol and linear catechol amide ligands and their use in selective metal ion removal recovery from aqueous solutions

    DOEpatents

    Fish, R.H.

    1998-11-10

    The present invention concerns the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis-catechol linear amide (PS-2-6-LICAMS) and sulfonated 3,3-linear tris-catechol amide (PS-3,3-LICAMS) ligands, which chemically bond to modified 6% crosslinked macroporous polystyrene-divinylbenzene beads (PS-DVB). These polymers are useful for the for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe{sup 3+} ion selectivity shown for PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Ni{sup 2+}, Mg{sup 2+}, Al{sup 3+}, and Cr{sup 3+} ions at pH 1--3. Further, the metal ion selectivity is changed at higher pH values in the absence of Fe{sup 3+} (for example, Hg{sup 2+} at pH 3). The rates of selective removal and recovery of the trivalent metal ions, e.g. Fe{sup 3+}, Al{sup 3+} ion etc. with the PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads used determined are useful as well as equilibrium selectivity coefficient (K{sub m}) values for all metal competition studies. The chelate effect for the predisposed octahedral PS-3,3-LICAMS polymer pendant ligand is the reason that this ligand has a more pronounced selectivity for Fe{sup 3+} ion in comparison to the PS-CATS polymer beads. The predisposed square planar PS-2,6-LICAMS series of polymer pendant ligands are more selective to divalent metal ions Cu{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Ni{sup 2+}, and Mg{sup 2+}, than either PS-CATS or PS-3,3-LICAMS. However, Fe{sup 3+} ion still dominates in competition with other divalent and trivalent metal ions. In the absence of Fe{sup 3+}, the polymer ligand is selective for Al{sup 3+}, Cu{sup 2+} or Hg{sup 2+}. The changing of the cavity size from two CH{sub 2} groups to six CH{sub 2} groups in the PS-2-6-LICAMS polymer pendant ligand series does not effect

  4. Polymer-supported sulfonated catechol and linear catechol amide ligands and their use in selective metal ion removal and recovery from aqueous solutions

    DOEpatents

    Fish, R.H.

    1997-04-22

    The present invention concerns the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis-catechol linear amide (PS-2-6-LICAMS) and sulfonated 3,3-linear tris-catechol amide (PS-3,3-LICAMS) ligands, which chemically bond to modified 6% crosslinked macroporous polystyrene-divinylbenzene beads (PS-DVB). These polymers are useful for the for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe{sup 3+} ion selectivity shown for PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Ni{sup 2+}, Mg{sup 2+}, Al{sup 3+}, and Cr{sup 3+} ions at pH 1--3. Further, the metal ion selectivity is changed at higher pH values in the absence of Fe{sup 3+} (for example, Hg{sup 2+} at pH 3). The rates of selective removal and recovery of the trivalent metal ions, e.g. Fe{sup 3+}, Al{sup 3+} ion etc. with the PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads use determined are useful as well as equilibrium selectivity coefficient (K{sub m}) values for all metal competition studies. The chelate effect for the predisposed octahedral PS-3,3-LICAMS polymer pendant ligand is the reason that this ligand has a more pronounced selectivity for Fe{sup 3+} ion in comparison to the PS-CATS polymer beads. The predisposed square planar PS-2-6-Mn{sup 2+}, Ni{sup 2+}, and Mg{sup 2+}, than either PS-CATS or PS-3,3-LICAMS. However, Fe{sup 3+} ion still dominates in competition with other divalent and trivalent metal ions. In the absence of Fe{sup 3+}, the polymer ligand is selective for Al{sup 3+}, Cu{sup 2+} or Hg{sup 2+}. The changing of the cavity size from two CH{sub 2} groups to six CH{sub 2} groups in the PS-2-6-LICAMS polymer pendant ligand series does not effect the order of metal ion selectivity. 9 figs.

  5. Fennel and anise as estrogenic agents.

    PubMed

    Albert-Puleo, M

    1980-12-01

    Fennel, Foeniculum vulgare, and anise, Pimpinella anisum, are plants which have been used as estrogenic agents for millennia. Specifically, they have been reputed to increase milk secretion, promote menstruation, facilitate birth, alleviate the symptoms of the male climacteric, and increase libido. In the 1930s, some interest was shown in these plants in the development of synthetic estrogens. The main constituent of the essential oils of fennel and anise, anethole, has been considered to be the active estrogenic agent. However, further research suggests that the actual pharmacologically active agents are polymers of anethole, such as dianethole and photoanethole. PMID:6999244

  6. [Study of estrogenic effects of promestriene].

    PubMed

    Gaudefroy, M; Pigache, J P

    1977-01-01

    Promestriene (3 propyl-ether-17 beta-methyl-ether of estradiol) a new estrogen molecule, conceived for local application has been formulated for gynecological use in a water soluble cream or lotion. The study of 27 women in advanced menopause lasted 20 weeks. In women with severe estrogen deficiencies the local application of promestriene induced a slight maturation of the trigonal or vaginal malpighian epithelium. It limited itself to a small growth of intermediary cells. There was a negligible action on the superficial cells. Linear regression analysis of different indices and maturation values according to Meisels and Hustin shows that even for prolonged treatments, there is little possibility of detrimental estrogenic action.

  7. Zinc acetylacetonate hydrate adducted with nitrogen donor ligands: Synthesis, spectroscopic characterization, and thermal analysis

    NASA Astrophysics Data System (ADS)

    Brahma, Sanjaya; Shivashankar, S. A.

    2015-12-01

    We report synthesis, spectroscopic characterization, and thermal analysis of zinc acetylacetonate complex adducted by nitrogen donor ligands, such as pyridine, bipyridine, and phenanthroline. The pyridine adducted complex crystallizes to monoclinic crystal structure, whereas other two adducted complexes have orthorhombic structure. Addition of nitrogen donor ligands enhances the thermal property of these complexes as that with parent metal-organic complex. Zinc acetylacetonate adducted with pyridine shows much higher volatility (106 °C), decomposition temperature (202 °C) as that with zinc acetylacetonate (136 °C, 220 °C), and other adducted complexes. All the adducted complexes are thermally stable, highly volatile and are considered to be suitable precursors for metal organic chemical vapor deposition. The formation of these complexes is confirmed by powder X-ray diffraction, Fourier transform infrared spectroscopy, mass spectroscopy, and elemental analysis. The complexes are widely used as starting precursor materials for the synthesis of ZnO nanostructures by microwave irradiation assisted coating process.

  8. Charge transfer adducts of metal complexes of π-donor ligands with I 2 and TCNQ

    NASA Astrophysics Data System (ADS)

    Bera, T. R.; Sen, D.; Ghosh, R.

    1989-01-01

    Copper(II) and nickel(II) biguanides and O-alkyl-1-amidinourea can act as donors for the formation of charge transfer (CT) adducts with I 2 and tetracyanoquinodimethane (TNCQ) as acceptors. Iodine adducts are characterized both in solid and solution states whereas TCNQ adducts obtain only in solution. Appearance of a broad band at 355 nm for iodine adducts and at 335 nm for TNCQ adducts and shifting of i.r. frequencies support the formation of donor acceptor associates. Elemental analysis establishes 1:1 stoichiometry of the solid adducts. The K and ɛ values determined by modified Benesi—Hildebrand, Scott and Rose—Drago equations are found to be of the order of 10 4 and 10 3 respectively at 298 K in methanol. The solvent effect on the K values is discussed in terms of coupled solute-solute and solute-solvent equilibria.

  9. Estrogen-related Receptor β Reduces the Subnuclear Mobility of Estrogen Receptor α and Suppresses Estrogen-dependent Cellular Function*

    PubMed Central

    Tanida, Takashi; Matsuda, Ken Ichi; Yamada, Shunji; Hashimoto, Takashi; Kawata, Mitsuhiro

    2015-01-01

    Estrogen-related receptor (ERR) is a member of the nuclear receptor superfamily that has strong homology with estrogen receptor (ER) α. ERR has three subtypes (α, β, and γ) expressed in estrogen-sensitive organs, including ovary, breast, and brain. No endogenous ligands of ERRs have been identified, but these receptors share a common DNA element with ERα and control estrogen-mediated gene transcription. Recent evidence suggests a role of ERRs in estrogen-related pathophysiology, but the detailed mechanisms of ERR functions in estrogen-related tissues are unclear. Using live-cell imaging with fluorescent protein labeling, we found that only ERRβ among the ERRs exhibits a punctate intranuclear pattern overlapping with ERα following 17β-estradiol (E2)-stimulation. Fluorescence recovery after photobleaching showed significant reduction of the mobility of ligand-activated ERα with co-expression of ERRβ. Fluorescence resonance energy transfer revealed that ERRβ directly interacts with ERα. The N-terminal domain of ERRβ was identified as the region that interacts with ERα. We also found a correlation between punctate cluster formation of ERα and interaction between the receptors. Expression of ERRβ significantly repressed ERα-mediated transactivity, whereas that of other ERR subtypes had no effect on the transactivity of ERα. Consistent with this finding, E2-stimulated proliferation of MCF-7 breast carcinoma cells and bcl-2 expression was significantly inhibited by expression of ERRβ. These results provide strong evidence for a suppressive effect of ERRβ on estrogen signaling through reduction of the intranuclear mobility of ERα. The findings further suggest a unique inhibitory role for ERRβ in estrogen-dependent cellular function such as cancer cell proliferation. PMID:25805499

  10. The expression of estrogen receptor and estrogen effect in MBA-15 marrow stromal osteoblasts.

    PubMed

    Shamay, A; Knopov, V; Benayahu, D

    1996-06-01

    MBA-15, a marrow stromal-derived cell line, was shown to express an estrogen receptor. This finding was confirmed by in situ hybridization and receptor binding assay. An exposure to estrogen (10(-12)-10(-6) M) in a dose response manner resulted in a decrease of cell proliferation as measured by MTT assay. Cell function was measured by enzymatic activities of two osteoblastic markers, CD10/NEP and alkaline phosphatase. These enzymatic activities were elevated following the estrogen treatment. This model enabled direct evaluation of the estrogen effect on stromal osteoblast cells. PMID:8858824

  11. Concentration of endogenous estrogens and estrogen metabolites in the NCI-60 human tumor cell lines

    PubMed Central

    2012-01-01

    Background Endogenous estrogens and estrogen metabolites play an important role in the pathogenesis and development of human breast, endometrial, and ovarian cancers. Increasing evidence also supports their involvement in the development of certain lung, colon and prostate cancers. Methods In this study we systemically surveyed endogenous estrogen and estrogen metabolite levels in each of the NCI-60 human tumor cell lines, which include human breast, central nerve system, colon, ovarian, prostate, kidney and non-small cell lung cancers, as well as melanomas and leukemia. The absolute abundances of these metabolites were measured using a liquid chromatography-tandem mass spectrometry method that has been previously utilized for biological fluids such as serum and urine. Results Endogenous estrogens and estrogen metabolites were found in all NCI-60 human tumor cell lines and some were substantially elevated and exceeded the levels found in well known estrogen-dependent and estrogen receptor-positive tumor cells such as MCF-7 and T-47D. While estrogens were expected to be present at high levels in cell lines representing the female reproductive system (that is, breast and ovarian), other cell lines, such as leukemia and colon, also contained very high levels of these steroid hormones. The leukemia cell line RMPI-8226 contained the highest levels of estrone (182.06 pg/106 cells) and 17β-estradiol (753.45 pg/106 cells). In comparison, the ovarian cancer cell line with the highest levels of these estrogens contained only 19.79 and 139.32 pg/106 cells of estrone and 17β-estradiol, respectively. The highest levels of estrone and 17β-estradiol in breast cancer cell lines were only 8.45 and 87.37 pg/106 cells in BT-549 and T-47D cells, respectively. Conclusions The data provided evidence for the presence of significant amounts of endogenous estrogens and estrogen metabolites in cell lines not commonly associated with these steroid hormones. This broad discovery of

  12. Chromium(VI) reduction by catechol(amine)s results in DNA cleavage in vitro: relevance to chromium genotoxicity.

    PubMed

    Pattison, D I; Davies, M J; Levina, A; Dixon, N E; Lay, P A

    2001-05-01

    Catechols are found extensively in nature both as essential biomolecules and as the byproducts of normal oxidative damage of amino acids and proteins. They are also present in cigarette smoke and other atmospheric pollutants. Here, the interactions of reactive species generated in Cr(VI)/catechol(amine) mixtures with plasmid DNA have been investigated to model a potential route to Cr(VI)-induced genotoxicity. Reduction of Cr(VI) by 3,4-dihydroxyphenylalanine (DOPA) (1), dopamine (2), or adrenaline (3) produces species that cause extensive DNA damage, but the products of similar reactions with catechol (4) or 4-tert-butylcatechol (5) do not damage DNA. The Cr(VI)/catechol(amine) reactions have been studied at low added H(2)O(2) concentrations, which lead to enhanced DNA cleavage with 1 and induce DNA cleavage with 4. The Cr(V) and organic intermediates generated by the reactions of Cr(VI) with 1 or 4 in the presence of H(2)O(2) were characterized by EPR spectroscopy. The detected signals were assigned to Cr(V)-catechol, Cr(V)-peroxo, and mixed Cr(V)-catechol-peroxo complexes. Oxygen consumption during the reactions of Cr(VI) with 1, 2, 4, and 5 was studied, and H(2)O(2) production was quantified. Reactions of Cr(VI) with 1 and 2, but not 4 and 5, consume considerable amounts of dissolved O(2), and give extensive H(2)O(2) production. Extents of oxygen consumption and H(2)O(2) production during the reaction of Cr(VI) with enzymatically generated 1 and N-acetyl-DOPA (from the reaction of Tyr and N-acetyl-Tyr with tyrosinase, respectively) were correlated with the DNA cleaving abilities of the products of these reactions. The reaction of Cr(VI) with enzymatically generated 1 produced significant amounts of H(2)O(2) and caused significant DNA damage, but the N-acetyl-DOPA did not. The extent of in vitro DNA damage is reduced considerably by treatment of the Cr(VI)/catechol(amine) mixtures with catalase, which shows that the DNA damage is H(2)O(2)-dependent and that the

  13. Structure of adducts of isoindolo[2,1-a]benzimidazole derivatives with maleimides

    NASA Astrophysics Data System (ADS)

    Korolev, Oleksandr; Yegorova, Tatyana; Levkov, Igor; Malytskyy, Volodymyr; Shishkin, Oleg; Zubatyuk, Roman; Palamarchuk, Genadiy; Vedrenne, Marc; Baltas, Michel; Voitenko, Zoia

    2015-03-01

    The selectivity of formation and some mechanistic insights during the synthesis of substituted isoindolo[2,1-a]benzimidazoles are discussed. Furthermore, the reactions of the obtained products with maleimides were carried out. Two types rearrangement adducts together with intermediate Michael type adducts were isolated. The influence of the reaction conditions and reagents ratio is discussed. Specific spectral criteria for the identification of the Michael type adducts are indicated.

  14. Catechol-Functionalized Synthetic Polymer as a Dental Adhesive to Contaminated Dentin Surface for a Composite Restoration.

    PubMed

    Lee, Sang-Bae; González-Cabezas, Carlos; Kim, Kwang-Mahn; Kim, Kyoung-Nam; Kuroda, Kenichi

    2015-08-10

    This study reports a synthetic polymer functionalized with catechol groups as dental adhesives. We hypothesize that a catechol-functionalized polymer functions as a dental adhesive for wet dentin surfaces, potentially eliminating the complications associated with saliva contamination. We prepared a random copolymer containing catechol and methoxyethyl groups in the side chains. The mechanical and adhesive properties of the polymer to dentin surface in the presence of water and salivary components were determined. It was found that the new polymer combined with an Fe(3+) additive improved bond strength of a commercial dental adhesive to artificial saliva contaminated dentin surface as compared to a control sample without the polymer. Histological analysis of the bonding structures showed no leakage pattern, probably due to the formation of Fe-catechol complexes, which reinforce the bonding structures. Cytotoxicity test showed that the polymers did not inhibit human gingival fibroblast cells proliferation. Results from this study suggest a potential to reduce failure of dental restorations due to saliva contamination using catechol-functionalized polymers as dental adhesives.

  15. Catechol-Functionalized Synthetic Polymer as a Dental Adhesive to Contaminated Dentin Surface for a Composite Restoration

    PubMed Central

    2015-01-01

    This study reports a synthetic polymer functionalized with catechol groups as dental adhesives. We hypothesize that a catechol-functionalized polymer functions as a dental adhesive for wet dentin surfaces, potentially eliminating the complications associated with saliva contamination. We prepared a random copolymer containing catechol and methoxyethyl groups in the side chains. The mechanical and adhesive properties of the polymer to dentin surface in the presence of water and salivary components were determined. It was found that the new polymer combined with an Fe3+ additive improved bond strength of a commercial dental adhesive to artificial saliva contaminated dentin surface as compared to a control sample without the polymer. Histological analysis of the bonding structures showed no leakage pattern, probably due to the formation of Fe–catechol complexes, which reinforce the bonding structures. Cytotoxicity test showed that the polymers did not inhibit human gingival fibroblast cells proliferation. Results from this study suggest a potential to reduce failure of dental restorations due to saliva contamination using catechol-functionalized polymers as dental adhesives. PMID:26176305

  16. Bioinformatics Analysis of Estrogen-Responsive Genes.

    PubMed

    Handel, Adam E

    2016-01-01

    Estrogen is a steroid hormone that plays critical roles in a myriad of intracellular pathways. The expression of many genes is regulated through the steroid hormone receptors ESR1 and ESR2. These bind to DNA and modulate the expression of target genes. Identification of estrogen target genes is greatly facilitated by the use of transcriptomic methods, such as RNA-seq and expression microarrays, and chromatin immunoprecipitation with massively parallel sequencing (ChIP-seq). Combining transcriptomic and ChIP-seq data enables a distinction to be drawn between direct and indirect estrogen target genes. This chapter discusses some methods of identifying estrogen target genes that do not require any expertise in programming languages or complex bioinformatics. PMID:26585125

  17. Correlation between Quadriceps Endurance and Adduction Moment in Medial Knee Osteoarthritis

    PubMed Central

    Ahn, Sung-Eun; Park, Min-Ji; Lee, Dae-Hee

    2015-01-01

    It is not clear whether the strength or endurance of thigh muscles (quadriceps and hamstring) is positively or negatively correlated with the adduction moment of osteoarthritic knees. This study therefore assessed the relationships between the strength and endurance of the quadriceps and hamstring muscles and adduction moment in osteoarthritic knees and evaluated predictors of the adduction moment. The study cohort comprised 35 patients with unilateral medial osteoarthritis and varus deformity who were candidates for open wedge osteotomy. The maximal torque (60°/sec) and total work (180°/sec) of the quadriceps and hamstring muscles and knee adduction moment were evaluated using an isokinetic testing device and gait analysis system. The total work of the quadriceps (r = 0.429, P = 0.037) and hamstring (r = 0.426, P = 0.045) muscles at 180°/sec each correlated with knee adduction moment. Preoperative varus deformity was positively correlated with adduction moment (r = 0.421, P = 0.041). Multiple linear regression analysis showed that quadriceps endurance at 180°/sec was the only factor independently associated with adduction moment (β = 0.790, P = 0.032). The adduction moment of osteoarthritic knees correlated with the endurance, but not the strength, of the quadriceps muscle. However, knee adduction moment did not correlate with the strength or endurance of the hamstring muscle. PMID:26539830

  18. Chromatographic and fluorescence spectroscopic studies of individual 7,12-dimethylbenz(a)anthracene--deoxyribonucleoside adducts

    SciTech Connect

    Moschel, R.C.; Pigott, M.A.; Costantino, N.; Dipple, A.

    1983-09-01

    Compared with standard Sephadex LH-20 column chromatography, a newly developed high pressure liquid chromatographic separation of hydrocarbon deoxyribonucleoside adducts derived from the DNA of mouse embryo cell cultures exposed to 7,12-dimethylbenz(a)anthracene (DMBA) provides markedly superior resolution. Once resolved, the fluorescence spectroscopic properties of the three major DMBA--DNA adducts indicate that the fluorescence exhibited by adducts derived from a bay region syn dihydrodiol epoxide of DMBA differs subtly from that exhibited by adducts derived from the isomeric anti dihydrodiol epoxide.

  19. Temporal and spatial features of the formation of DNA adducts in sulfur mustard-exposed skin

    SciTech Connect

    Batal, Mohamed; Boudry, Isabelle; Mouret, Stéphane; Wartelle, Julien; Emorine, Sandy; Bertoni, Marine; Bérard, Izabel; and others

    2013-12-15

    Sulfur mustard (SM) is a chemical warfare agent that targets skin where it induces large blisters. DNA alkylation is a critical step to explain SM-induced cutaneous symptoms. We determined the kinetics of formation of main SM–DNA adducts and compare it with the development of the SM-induced pathogenesis in skin. SKH-1 mice were exposed to 2, 6 and 60 mg/kg of SM and treated skin was biopsied between 6 h and 21 days. Formation of SM DNA adducts was dose-dependent with a maximum immediately after exposure. However, adducts were persistent and still detectable 21 days post-exposure. The time-dependent formation of DNA adducts was also found to be correlated with the appearance of apoptotic cells. This temporal correlation suggests that these two early events are responsible for the severity of the damage to the skin. Besides, SM–DNA adducts were also detected in areas located next to contaminated zone, thus suggesting that SM diffuses in skin. Altogether, this work provides for the first time a clear picture of SM-induced genotoxicity using DNA adducts as a marker. - Highlights: • Sulfur mustard adducts are formed in DNA after skin exposure. • DNA damage formation is an early event in the pathological process of skin burn. • The amount of SM–DNA adducts is maximal at the earliest time point investigated. • Adducts are still detected 3 weeks after exposure. • Sulfur mustard diffuses in skin especially when large doses are applied.

  20. Correlation between Quadriceps Endurance and Adduction Moment in Medial Knee Osteoarthritis.

    PubMed

    Lee, Soon-Hyuck; Lee, Jin-Hyuck; Ahn, Sung-Eun; Park, Min-Ji; Lee, Dae-Hee

    2015-01-01

    It is not clear whether the strength or endurance of thigh muscles (quadriceps and hamstring) is positively or negatively correlated with the adduction moment of osteoarthritic knees. This study therefore assessed the relationships between the strength and endurance of the quadriceps and hamstring muscles and adduction moment in osteoarthritic knees and evaluated predictors of the adduction moment. The study cohort comprised 35 patients with unilateral medial osteoarthritis and varus deformity who were candidates for open wedge osteotomy. The maximal torque (60°/sec) and total work (180°/sec) of the quadriceps and hamstring muscles and knee adduction moment were evaluated using an isokinetic testing device and gait analysis system. The total work of the quadriceps (r = 0.429, P = 0.037) and hamstring (r = 0.426, P = 0.045) muscles at 180°/sec each correlated with knee adduction moment. Preoperative varus deformity was positively correlated with adduction moment (r = 0.421, P = 0.041). Multiple linear regression analysis showed that quadriceps endurance at 180°/sec was the only factor independently associated with adduction moment (β = 0.790, P = 0.032). The adduction moment of osteoarthritic knees correlated with the endurance, but not the strength, of the quadriceps muscle. However, knee adduction moment did not correlate with the strength or endurance of the hamstring muscle.

  1. Comparison of DNA adducts from exposure to complex mixtures in various human tissues and experimental systems

    PubMed Central

    Lewtas, Joellen; Mumford, Judy; Everson, Richard B.; Hulka, Barbara; Wilcosky, Tim; Kozumbo, Walter; Thompson, Claudia; George, Michael; Dobiáš, Lubomir; Šrám, Radim; Li, Xueming; Gallagher, Jane

    1993-01-01

    DNA adducts derived from complex mixtures of polycyclic aromatic compounds emitted from tobacco smoke are compared to industrial pollution sources (e.g., coke ovens and aluminum smelters), smoky coal burning, and urban air pollution. Exposures to coke oven emissions and smoky coal, both potent rodent skin tumor initiators and lung carcinogens in humans, result in high levels of DNA adducts compared to tobacco smoke in the in vitro calf thymus DNA model system, in cultured lymphocytes, and in the mouse skin assay. Using tobacco smoke as a model in human studies, we have compared relative DNA adduct levels detected in blood lymphocytes, placental tissue, bronchoalveolar lung lavage cells, sperm, and autopsy tissues of smokers and nonsmokers. Adduct levels in DNA isolated from smokers were highest in human heart and lung tissue with smaller but detectable differences in placental tissue and lung lavage cells. Comparison of the DNA adduct levels resulting from human exposure to different complex mixtures shows that emissions from coke ovens, aluminum smelters, and smoky coal result in higher DNA adduct levels than tobacco smoke exposure. These studies suggest that humans exposed to complex combustion mixtures will have higher DNA adduct levels in target cells (e.g., lung) as compared to nontarget cells (e.g., lymphocytes) and that the adduct levels will be dependent on the genotoxic and DNA adduct-forming potency of the mixture. ImagesFIGURE 1.FIGURE 1.FIGURE 2.FIGURE 3.FIGURE 3.FIGURE 3.FIGURE 3.FIGURE 3.FIGURE 3.FIGURE 4. PMID:8319665

  2. Dynamic Adduction Angle of Forefoot Measured With a Novel Technique And Its Relationship With Functional Outcomes

    PubMed Central

    Amin, Nirav Hasmukh; Jakoi, Andre; Alexander, Volpi MS; Morrison, Martin Joseph; Trobisch, Per

    2016-01-01

    Background Idiopathic clubfoot is commonly treated with the Ponseti method with the extent of invasive treatment involving tendon-Achilles lengthening. Forefoot adduction is a common complication in surgically treated clubfeet. Yet, no method has been described to measure dynamic (walking) forefoot adduction. The aim of this study was to assess the persistent pes adductus in children whose clubfeet were surgically treated using a dorsomedial soft tissue release and to find out correlations between forefoot adduction and clinical outcome measures. Methods We analysed the dynamic adduction angle in 33 clubfeet using a pressure-sensitive foot platform and compared it to the healthy feet of an age- and weight-matched group of children without congenital foot deformities. The clinical outcome was analysed using the McKay score. Results Mean dynamic adduction angle was 4.1o in the surgically corrected clubfeet, whereas it was 6.4° in unaffected feet of patients with unilateral clubfoot and 7.1o in control group. The McKay score were excellent in 1 patient, good in 5, average in 13, and fair in 4 of the 23 patients. There was no correlation between dynamic adduction angle and McKay score using paired t test (P > 0.05). Conclusion High occurrence of dynamic adduction angle in surgically treated clubfeet was detected. In conclusion, no correlation between forefoot adduction, dynamic forefoot adduction angle and clinical outcome measures within the study was observed. PMID:27547113

  3. Lifetimes and stabilities of familiar explosives molecular adduct complexes during ion mobility measurements

    PubMed Central

    McKenzie, Alan; DeBord, John Daniel; Ridgeway, Mark; Park, Melvin; Eiceman, Gary; Fernandez-Lima, Francisco

    2015-01-01

    Trapped ion mobility spectrometry coupled to mass spectrometry (TIMS-MS) was utilized for the separation and identification of familiar explosives in complex mixtures. For the first time, molecular adduct complex lifetimes, relative stability, binding energies and candidate structures are reported for familiar explosives. Experimental and theoretical results showed that the adduct size and reactivity, complex binding energy and the explosive structure tailors the stability of the molecular adduct complex. TIMS flexibility to adapt the mobility separation as a function of the molecular adduct complex stability (i.e., short or long IMS experiments / low or high IMS resolution) permits targeted measurements of explosives in complex mixtures with higher confidence levels. PMID:26153567

  4. Pyrolysis of wastewater biosolids significantly reduces estrogenicity.

    PubMed

    Hoffman, T C; Zitomer, D H; McNamara, P J

    2016-11-01

    Most wastewater treatment processes are not specifically designed to remove micropollutants. Many micropollutants are hydrophobic so they remain in the biosolids and are discharged to the environment through land-application of biosolids. Micropollutants encompass a broad range of organic chemicals, including estrogenic compounds (natural and synthetic) that reside in the environment, a.k.a. environmental estrogens. Public concern over land application of biosolids stemming from the occurrence of micropollutants hampers the value of biosolids which are important to wastewater treatment plants as a valuable by-product. This research evaluated pyrolysis, the partial decomposition of organic material in an oxygen-deprived system under high temperatures, as a biosolids treatment process that could remove estrogenic compounds from solids while producing a less hormonally active biochar for soil amendment. The estrogenicity, measured in estradiol equivalents (EEQ) by the yeast estrogen screen (YES) assay, of pyrolyzed biosolids was compared to primary and anaerobically digested biosolids. The estrogenic responses from primary solids and anaerobically digested solids were not statistically significantly different, but pyrolysis of anaerobically digested solids resulted in a significant reduction in EEQ; increasing pyrolysis temperature from 100°C to 500°C increased the removal of EEQ with greater than 95% removal occurring at or above 400°C. This research demonstrates that biosolids treatment with pyrolysis would substantially decrease (removal>95%) the estrogens associated with this biosolids product. Thus, pyrolysis of biosolids can be used to produce a valuable soil amendment product, biochar, that minimizes discharge of estrogens to the environment. PMID:27344259

  5. Estrogenic activity in Finnish municipal wastewater effluents.

    PubMed

    Välitalo, Pia; Perkola, Noora; Seiler, Thomas-Benjamin; Sillanpää, Markus; Kuckelkorn, Jochen; Mikola, Anna; Hollert, Henner; Schultz, Eija

    2016-01-01

    Effluents from wastewater treatment plants (WWTPs) are a major source of estrogenic compounds to the aquatic environment. In the present work, estrogenic activities of effluents from eight municipal WWTPs in Finland were studied. The main objectives of the study were to quantify the concentrations of selected estrogenic compounds, to evaluate their contribution to estrogenic potency and to test the feasibility of the commercial bioassays for wastewater analysis. The effluent samples were analyzed by two in vitro tests, i.e. ERα-CALUX(®) and ELISA-E2, and by liquid chromatography mass spectrometry for six estrogenic compounds: estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethinylestradiol (EE2), 17α-estradiol and bisphenol A (BPA). Estrogenic effects were found in all of the effluent samples with both of the bioassays. The concentrations measured with ELISA-E2 (8.6-61.6 ng/L) were clearly higher but exhibited a similar pattern than those with chemical analysis (E2 estrogenic potency was possible only for E1 and BPA, which contributed less than 10% to the observed effects, except in one sample with a high BPA contribution (17%). The contribution of E2 was significant in two samples where it was detected (28% and 67%). The results demonstrated that more comprehensive information on potential estrogenic activity of wastewater effluents can be achieved by using in vitro biotests in addition to chemical analysis and their use would be beneficial in monitoring and screening purposes. PMID:26584345

  6. In vitro screening of 50 highly prescribed drugs for thiol adduct formation--comparison of potential for drug-induced toxicity and extent of adduct formation.

    PubMed

    Gan, Jinping; Ruan, Qian; He, Bing; Zhu, Mingshe; Shyu, Wen C; Humphreys, W Griffith

    2009-04-01

    Reactive metabolite formation has been associated with drug-induced liver, skin, and hematopoietic toxicity of many drugs that has resulted in serious clinical toxicity, leading to clinical development failure, black box warnings, or, in some cases, withdrawal from the market. In vitro and in vivo screening for reactive metabolite formation has been proposed and widely adopted in the pharmaceutical industry with the aim of minimizing the property and thus the risk of drug-induced toxicity (DIT). One of the most common screening methods is in vitro thiol trapping of reactive metabolites. Although it is well-documented that many hepatotoxins form thiol adducts, there is no literature describing the adduct formation potential of safer drugs that are widely used. The objective of this study was to quantitatively assess the thiol adduct formation potential of 50 drugs (10 associated with DIT and 40 not associated) and document apparent differences in adduct formation between toxic and safer drugs. Dansyl glutathione was used as a trapping agent to aid the quantitation of adducts following in vitro incubation of drugs with human liver microsomes in the presence and absence of NADPH. Metabolic turnover of these drugs was also monitored by LC/UV. Overall, 15 out of the 50 drugs screened formed detectable levels of thiol adducts. There were general trends toward more positive findings in the DIT group vs the non-DIT group. These trends became more marked when the relative amount of thiol adducts was taken into account and improved further when dose and total daily reactive metabolite burdens were considered. In conclusion, there appears to be a general trend between the extent of thiol adduct formation and the potential for DIT, which would support the preclinical measurement and minimization of the property through screening of thiol adduct formation as part of an overall discovery optimization paradigm. PMID:19253935

  7. Estrogen effects in allergy and asthma

    PubMed Central

    Bonds, Rana S.; Midoro-Horiuti, Terumi

    2012-01-01

    Purpose of review Asthma prevalence and severity are greater in women than in men, and mounting evidence suggests this is in part related to female steroid sex hormones. Of these, estrogen has been the subject of much study. This review highlights recent research exploring the effects of estrogen in allergic disease. Recent findings Estrogen receptors are found on numerous immunoregulatory cells and estrogen’s actions skew immune responses toward allergy. It may act directly to create deleterious effects in asthma, or indirectly via modulation of various pathways including secretory leukoprotease inhibitor, transient receptor potential vanilloid type 1 ion channel and nitric oxide production to exert effects on lung mechanics and inflammation. Not only do endogenous estrogens appear to play a role, but environmental estrogens have also been implicated. Environmental estrogens (xenoestrogens) including bisphenol A and phthalates enhance allergic sensitization in animal models and may enhance development of atopic disorders like asthma in humans. Summary Estrogen’s role in allergic disease remains complex. As allergic diseases continue to increase in prevalence and affect women disproportionately, gaining a fuller understanding of its effects in these disorders will be essential. Of particular importance may be effects of xenoestrogens on allergic disease. PMID:23090385

  8. Estrogen Biosynthesis and Action in Ovarian Cancer

    PubMed Central

    Mungenast, Felicitas; Thalhammer, Theresia

    2014-01-01

    Ovarian cancer is still the deadliest of all gynecologic malignancies in women worldwide. This is attributed to two main features of these tumors, namely, (i) a diagnosis at an advanced tumor stage, and, (ii) the rapid onset of resistance to standard chemotherapy after an initial successful therapy with platin- and taxol-derivatives. Therefore, novel targets for an early diagnosis and better treatment options for these tumors are urgently needed. Epidemiological data show that induction and biology of ovarian cancer is related to life-time estrogen exposure. Also experimental data reveal that ovarian cancer cells share a number of estrogen regulated pathways with other hormone-dependent cancers, e.g., breast and endometrial cancer. However, ovarian cancer is a heterogeneous disease and the subtypes are quite different with respect to mutations, origins, behaviors, markers, and prognosis and respond differently to standard chemotherapy. Therefore, a characterization of ovarian cancer subtypes may lead to better treatment options for the various subtypes and in particular for the most frequently observed high-grade serous ovarian carcinoma. For this intention, further studies on estrogen-related pathways and estrogen formation in ovarian cancer cells are warranted. The review gives an overview on ovarian cancer subtypes and explains the role of estrogen in ovarian cancer. Furthermore, enzymes active to synthesize and metabolize estrogens are described and strategies to target these pathways are discussed. PMID:25429284

  9. The molecular, cellular and clinical consequences of targeting the estrogen receptor following estrogen deprivation therapy.

    PubMed

    Fan, Ping; Maximov, Philipp Y; Curpan, Ramona F; Abderrahman, Balkees; Jordan, V Craig

    2015-12-15

    During the past 20 years our understanding of the control of breast tumor development, growth and survival has changed dramatically. The once long forgotten application of high dose synthetic estrogen therapy as the first chemical therapy to treat any cancer has been resurrected, refined and reinvented as the new biology of estrogen-induced apoptosis. High dose estrogen therapy was cast aside once tamoxifen, from its origins as a failed "morning after pill", was reinvented as the first targeted therapy to treat any cancer. The current understanding of the mechanism of estrogen-induced apoptosis is described as a consequence of acquired resistance to long term antihormone therapy in estrogen receptor (ER) positive breast cancer. The ER signal transduction pathway remains a target for therapy in breast cancer despite "antiestrogen" resistance, but becomes a regulator of resistance. Multiple mechanisms of resistance come into play: Selective ER modulator (SERM) stimulated growth, growth factor/ER crosstalk, estrogen-induced apoptosis and mutations of ER. But it is with the science of estrogen-induced apoptosis that the next innovation in women's health will be developed. Recent evidence suggests that the glucocorticoid properties of medroxyprogesterone acetate blunt estrogen-induced apoptosis in estrogen deprived breast cancer cell populations. As a result breast cancer develops during long-term hormone replacement therapy (HRT). A new synthetic progestin with estrogen-like properties, such as the 19 nortestosterone derivatives used in oral contraceptives, will continue to protect the uterus from unopposed estrogen stimulation but at the same time, reinforce apoptosis in vulnerable populations of nascent breast cancer cells.

  10. Mixed estrogenic and anti-estrogenic activities of yuehchukene--a bis-indole alkaloid.

    PubMed

    Ng, P C; Ho, D D; Ng, K H; Kong, Y C; Cheng, K F; Stone, G

    1994-10-13

    Anti-estrogenic effects of yuehchukene were observed in rat uterotrophic, mice vaginal smear and MCF-7 cell growth assays. Whereas yuehchukene per se was estrogenic in these bioassay models, the co-administration of yuehchukene and an optimal dose of 3,17 beta-estradiol (estradiol) could attenuate the maximum estrogenic response due to estradiol alone. The anti-estrogenic effect of yuehchukene in rat uterine hypertrophy was corroborated by a parallel attenuation of ornithine decarboxylase activity in these tissues. Yuehchukene binds to rat, mice and MCF-7 cell estrogen receptors with a relative binding affinity of 1/150 to 1/300. This binding affinity was positively related to estrogenicity as determined by uterotrophic assay and MCF-7 cell growth. However, this estrogenic effect did not correlate with the degree of competitive receptor binding by a weaker agonist. Indole-3-carbinol and methylbutadienylindole could induce ethoxyresorufin O-deethylase and estradiol-2-hydroxylase in rat liver and MCF-7 cells. It is postulated that the 'free' indole moiety of yuehchukene could possess similar induction activity. Thus yuehchukene may have a dual pharmacological function. While the intact molecule is a weak estrogen, the 'free' indole moiety in yuehchukene may induce an enhancement of estradiol-2-hydroxylase, thus terminating the biological activity of the endogenous estrogen pool. There is obvious benefit in attenuating the estrogen level in post-menopausal breast cancer patients without going directly to the use of tamoxifen or aromatase inhibitor. Yuehchukene may serve this purpose. In this context, the pharmacological evaluation of a hydroxylated yuehchukene analogue and the anti-estrogenic effect of methylbutadienylindole acid-condensation products are now being studied in earnest.

  11. Estrogenic activity assessment of environmental chemicals using in vitro assays: identification of two new estrogenic compounds.

    PubMed Central

    Lascombe, I; Beffa, D; Rüegg, U; Tarradellas, J; Wahli, W

    2000-01-01

    Environmental chemicals with estrogenic activities have been suggested to be associated with deleterious effects in animals and humans. To characterize estrogenic chemicals and their mechanisms of action, we established in vitro and cell culture assays that detect human estrogen receptor [alpha] (hER[alpha])-mediated estrogenicity. First, we assayed chemicals to determine their ability to modulate direct interaction between the hER[alpha] and the steroid receptor coactivator-1 (SRC-1) and in a competition binding assay to displace 17ss-estradiol (E(2)). Second, we tested the chemicals for estrogen-associated transcriptional activity in the yeast estrogen screen and in the estrogen-responsive MCF-7 human breast cancer cell line. The chemicals investigated in this study were o,p'-DDT (racemic mixture and enantiomers), nonylphenol mixture (NPm), and two poorly analyzed compounds in the environment, namely, tris-4-(chlorophenyl)methane (Tris-H) and tris-4-(chlorophenyl)methanol (Tris-OH). In both yeast and MCF-7 cells, we determined estrogenic activity via the estrogen receptor (ER) for o,p'-DDT, NPm, and for the very first time, Tris-H and Tris-OH. However, unlike estrogens, none of these xenobiotics seemed to be able to induce ER/SRC-1 interactions, most likely because the conformation of the activated receptor would not allow direct contacts with this coactivator. However, these compounds were able to inhibit [(3)H]-E(2) binding to hER, which reveals a direct interaction with the receptor. In conclusion, the test compounds are estrogen mimics, but their molecular mechanism of action appears to be different from that of the natural hormone as revealed by the receptor/coactivator interaction analysis. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 PMID:10903615

  12. Resveratrol and N-acetylcysteine block the cancer-initiating step in MCF-10F cells

    PubMed Central

    Zahid, Muhammad; Saeed, Muhammad; Beseler, Cheryl; Rogan, Eleanor G.; Cavalieri, Ercole L.

    2015-01-01

    Substantial evidence suggests that catechol estrogen-3,4-quinones react with DNA to form predominantly the depurinating adducts 4-hydroxyestrone (estradiol)-1-N3Ade [4-OHE1(E2)-1-N3Ade] and 4-OHE1(E2)-1-N7Gua. Apurinic sites resulting from these adducts generate critical mutations that can initiate cancer. The paradigm of cancer initiation is based on an imbalance in estrogen metabolism between activating pathways that lead to estrogen–DNA adducts and deactivating pathways that lead to estrogen metabolites and conjugates. This imbalance can be improved to minimize formation of adducts by using antioxidants, such as resveratrol (Resv) and N-acetylcysteine (NAcCys). To compare the ability of Resv and NAcCys to block formation of estrogen–DNA adducts, we used the human breast epithelial cell line MCF-10F treated with 4-OHE2. Resv and NAcCys directed the metabolism of 4-OHE2 toward protective pathways. NAcCys reacted with the quinones and reduced the semiquinones to catechols. This pathway was also carried out by Resv. In addition, Resv induced the protective enzyme quinone reductase, which reduces E1(E2)-3,4-quinones to 4-OHE1(E2). Resv was more effective at increasing the amount of 4-OCH3E1(E2) than NAcCys. Inhibition of estrogen–DNA adduct formation was similar at lower doses, but at higher doses Resv was about 50% more effective than NAcCys. Their combined effects were additive. Therefore, these two antioxidants provide an excellent combination to protect catechol estrogens from oxidation to catechol quinones. PMID:20934508

  13. Escherichia coli responses to a single DNA adduct.

    PubMed

    Pandya, G A; Yang, I Y; Grollman, A P; Moriya, M

    2000-12-01

    To study the mechanisms by which Escherichia coli modulates the genotoxic effects of DNA damage, a novel system has been developed which permits quantitative measurements of various E. coli pathways involved in mutagenesis and DNA repair. Events measured include fidelity and efficiency of translesion DNA synthesis, excision repair, and recombination repair. Our strategy involves heteroduplex plasmid DNA bearing a single site-specific DNA adduct and several mismatched regions. The plasmid replicates in a mismatch repair-deficient host with the mismatches serving as strand-specific markers. Analysis of progeny plasmid DNA for linkage of the strand-specific markers identifies the pathway from which the plasmid is derived. Using this approach, a single 1, N(6)-ethenodeoxyadenosine adduct was shown to be repaired inefficiently by excision repair, to inhibit DNA synthesis by approximately 80 to 90%, and to direct the incorporation of correct dTMP opposite this adduct. This approach is especially useful in analyzing the damage avoidance-tolerance mechanisms. Our results also show that (i) progeny derived from the damage avoidance-tolerance pathway(s) accounts for more than 15% of all progeny; (ii) this pathway(s) requires functional recA, recF, recO, and recR genes, suggesting the mechanism to be daughter strand gap repair; (iii) the ruvABC genes or the recG gene is also required; and (iv) the RecG pathway appears to be more active than the RuvABC pathway. Based on these results, the mechanism of the damage avoidance-tolerance pathway is discussed. PMID:11073901

  14. Quaternary ammonium functionalized clay film electrodes modified with polyphenol oxidase for the sensitive detection of catechol.

    PubMed

    Mbouguen, Justin Kemmegne; Ngameni, Emmanuel; Walcarius, Alain

    2007-09-30

    Naturally occurring Cameroonian smectite clay has been grafted with trimethylpropylammonium (TMPA) groups and the resulting organoclay has been deposited onto a glassy carbon electrode surface as a suitable immobilization matrix for polyphenol oxidase (PPO). High sensitivity of the electrochemical device to catechol biosensing can be achieved when the enzyme was impregnated within the organoclay film subsequent to its deposition due to favorable electrostatic interaction between PPO and the TMPA-clay layer. The bioelectrode preparation method was also compatible with the use of a mediator (i.e., ferrocene) and the best performance was obtained with a three-layer configuration made of glassy carbon coated with a first layer of ferrocene (Fc), which was then covered with the PPO-impregnated TMPA-clay layer, and finally overcoated with an enzyme-free TMPA-clay film acting as a protecting overlayer to avoid leaching of the biomolecule in solution. The electrochemical behavior of the modified film electrodes was first characterized by cyclic voltammetry and, then, they were evaluated for the amperometric biosensing of the model analyte catechol in batch conditions and in flow injection analysis. Various experimental parameters likely to influence the biosensor response have been investigated, including the electrode preparation mode (composition configuration, thickness), the usefulness of a mediator, the operating potential and pH of the medium, as well as the advantageous features of the TMPA-clay in comparison to related film electrodes based on non-functionalized clays. The organoclay was found to provide a favorable environment to enzyme activity and the multilayer configuration of the film electrode to provide a biosensor with good characteristics, such as an extended linear range for catechol detection (2 x 10(-8) to 1.2 x 10(-5)M) and a detection limit in the nanomolar range (9 x 10(-9)M). PMID:17537626

  15. Phorbol myristate acetate and catechol as skin cocarcinogens in SENCAR mice

    SciTech Connect

    Van Duuren, B.L.; Melchionne, S.; Seidman, I.

    1986-09-01

    The enhancement of the carcinogenicity of benzo(a) pyrene (B(a)P) and ..beta..-propiolactone (BPL) by the mouse skin cocarcinogens phorbol myristate acetate (PMA) and catechol were examined in female SENCAR mice, 30 per group. The carcinogen and cocarcinogen were applied simultaneously, three times weekly for 490-560 days. B(a)P and BPL were used at constant doses of 5 and 50 ..mu..g, respectively, in all experiments. PMA was used at three doses, 2.5, 1.0, and 0.5 ..mu..g per application, and catechol was used at one dose, 2 mg per application. Control groups included animals that received carcinogen only, cocarcinogen only, acetone only, and no treatment. The carcinogenicity of B(a)P and BPL were enhanced by the cocarcinogens, particularly in terms of tumor multiplicity. For both carcinogens, the most marked cocarcinogenic effects were observed at the lowest dose of PMA used (0.5 ..mu..g per application). This observation applied for days to first tumor, animals with tumors, tumor multiplicity, and incidence of malignant skin tumors. Catechol applied alone did not induce any tumors; with PMA alone there were significant incidences of benign and malignant tumors, e.g., at a dose of only 0.5 ..mu..g per application, 15 of 30 animals had 28 tumors, 5 of which were squamous carcinomas. In two-stage carcinogenesis experiments with 7,12-dimethylbenz(a)anthracene (DMBA) as initiator and PMA as promoter, SENCAR mice showed a greater susceptibility to tumor induction when compared to ICR/Ha mice used in earlier work. This susceptibility was most notable in terms of rate of tumor appearance and tumor multiplicity.

  16. Detection of mitomycin C-DNA adducts in vivo by 32P-postlabeling: time course for formation and removal of adducts and biochemical modulation.

    PubMed

    Warren, A J; Maccubbin, A E; Hamilton, J W

    1998-02-01

    Mitomycin C (MMC) is a DNA cross-linking agent that has been used in cancer chemotherapy for over 20 years, yet little is known either qualitatively or quantitatively about MMC-induced DNA adduct formation and repair in vivo. As an initial means of investigating this, we used a recently developed 32P-postlabeling assay to examine the formation and loss of MMC-DNA adducts in the tissues of a simple in vivo model test system, the chick embryo, following treatment with a chemotherapeutic dose of MMC. As early as 15 min after MMC treatment, four adducts could be detected in the liver which were tentatively identified as the (CpG) N2G-MMC-N2G interstrand cross-link, the bifunctionally activated MMC-N2G monoadduct, and two isomers (alpha and beta) of the monofunctionally activated MMC-N2G monoadduct. The (GpG) N2G-MMC-N2G intrastrand cross-link appears to be a poor substrate for nuclease P1 and/or T4 kinase and was not evaluable by this assay. Levels of all four detectable adducts increased substantially within the first 2 h after MMC treatment, reached maximal levels by 6 h, and decreased progressively thereafter through 24 h, although low levels of certain adducts persisted beyond 24 h. Lung and kidney had comparable levels of total MMC adducts, which were approximately 60% those of the liver, and there were no significant differences in the proportion of specific adducts among the three tissues. The interstrand cross-link represented approximately 13-14% of the total MMC adducts, which is approximately 5-fold greater than the proportion of CpG sites in the genome. In addition, the interstrand cross-link was selectively decreased after 16 h relative to the three monoadducts, suggesting preferential repair. The effect of modulating different components of the Phase I and Phase II drug metabolism on MMC adduct formation, using either glutethimide, 3,4,3',4'-tetrachlorobiphenyl, dexamethasone, buthionine sulfoximine, ethacrynic acid, or N-acetylcysteine pretreatments, was

  17. Formation and persistence of arylamine DNA adducts in vivo.

    PubMed Central

    Beland, F A; Kadlubar, F F

    1985-01-01

    Aromatic amines are urinary bladder carcinogens in man and induce tumors at a number of sites in experimental animals including the liver, mammary gland, intestine, and bladder. In this review, the particular pathways involved in the metabolic activation of aromatic amines are considered as well as the specific DNA adducts formed in target and nontarget tissue. Particular emphasis is placed on the following compounds: 1-naphthylamine, 2-naphthylamine, 4-aminobiphenyl, 4-acetylaminobiphenyl, 4-acetylamino-4'-fluorobiphenyl, 3,2'-dimethyl-4-aminobiphenyl, 2-acetylaminofluorene, benzidine, N-methyl-4-aminoazobenzene, 4-aminoazobenzene, and 2-acetylaminophenanthrene. PMID:4085422

  18. Dioxygenase- and monooxygenase-catalysed synthesis of cis-dihydrodiols, catechols, epoxides and other oxygenated products.

    PubMed

    Nolan, Louise C; O'Connor, Kevin E

    2008-11-01

    Oxidoreductases are an emerging class of biotechnologically relevant enzymes due to their regio- and stereo-specificity. The selective oxygenation of aromatic compounds by oxidoreductases has received much attention and a wide range of reactions have been documented using these enzymes from various microbial sources. This review gives an overview of various dioxygenase, monooxygenase and oxidase enzymes that have been manipulated for the synthesis of products such as cis-dihydrodiols, catechols, epoxides and other oxygenated products. The use of protein engineering and its advancement in the synthesis of recombinant enzymes is also discussed.

  19. Crystallization and preliminary crystallographic characterization of catechol-O-methyltransferase in complex with its cosubstrate and an inhibitor.

    PubMed

    Rodrigues, M L; Archer, M; Bonifácio, M J; Soares-da-Silva, P; Carrondo, M A

    2001-06-01

    Catechol-O-methyltransferase (COMT) is involved in the metabolism of catecholamines, catechol steroids and xenobiotic catechols. A precise knowledge of the enzyme-inhibitor structural interactions could help in the design of better inhibitors. Soluble rat COMT was expressed in Escherichia coli and the recombinant protein was crystallized with a new tight-binding inhibitor, BIA 3-335 [1-(3,4-dihydroxy-5-nitrophenyl)-3-(n-3'-trifluoromethylphenyl)piperazine-1-propanone dihydrochloride]. The crystals were obtained by the sitting-drop vapour-diffusion method using PEG 6K as a precipitant. These crystals diffracted to better than 1.9 A and belong to the trigonal space group P3(2)21. The unit-cell parameters for the crystal measured at room temperature were a = b = 51.5, c = 168.3 A; each shrank by about 1 A on freezing. PMID:11375525

  20. Kinetic study of the oxidation and nitration of catechols in the presence of nitrous acid ionization equilibria.

    PubMed

    Khalafi, Lida; Rafiee, Mohammad

    2010-02-15

    Conversion of catechols to corresponding nitro derivatives in the presence of nitrous acid dissociation is studied using voltammetry and UV-vis spectrophotometry. The results indicate that the quinones derived from oxidation of catechols by nitrous acid participate in Michael addition reaction with nitrite ion in very mild acidic solutions. Rank annihilation factor analysis RAFA is applied to resolve the two-way kinetic spectra data measured from spectroscopic reactions. The rank of the original data matrix is reduced by one by annihilating the information of each component. It is shown that both reactions are drastically depends on pH and nitrous acid or nitrite ion percentage. The rate constants of oxidation and nitration reactions of catechol derivatives are obtained at the pHs around pK(a) of nitrous acid.

  1. MODELING THE EFFECTS OF FLEXIBILITY ON THE BINDING OF ENVIRONMENTAL ESTROGENS TO THE ESTROGEN RECEPTOR

    EPA Science Inventory

    Modeling the effects of flexibility on the binding of environmental estrogens to the estrogen receptor
    There are many reports of environmental endocrine disruption in the literature, yet it has been difficult to identify the specific chemicals responsible for these effects. ...

  2. Binding of Estrogenic Compounds to Recombinant Estrogen Receptor-α: Application to Environmental Analysis

    PubMed Central

    Pillon, Arnaud; Boussioux, Anne-Marie; Escande, Aurélie; Aït-Aïssa, Sélim; Gomez, Elena; Fenet, Hélène; Ruff, Marc; Moras, Dino; Vignon, Françoise; Duchesne, Marie-Josèphe; Casellas, Claude; Nicolas, Jean-Claude; Balaguer, Patrick

    2005-01-01

    Estrogenic activity in environmental samples could be mediated through a wide variety of compounds and by various mechanisms. High-affinity compounds for estrogen receptors (ERs), such as natural or synthetic estrogens, as well as low-affinity compounds such as alkylphenols, phthalates, and polychlorinated biphenyls are present in water and sediment samples. Furthermore, compounds such as polycyclic aromatic hydrocarbons, which do not bind ERs, modulate estrogen activity by means of the aryl hydrocarbon receptor (AhR). In order to characterize compounds that mediate estrogenic activity in river water and sediment samples, we developed a tool based on the ER-αligand-binding domain, which permitted us to estimate contaminating estrogenic compound affinities. We designed a simple transactivation assay in which compounds of high affinity were captured by limited amounts of recombinant ER-αand whose capture led to a selective inhibition of transactivation. This approach allowed us to bring to light that water samples contain estrogenic compounds that display a high affinity for ERs but are present at low concentrations. In sediment samples, on the contrary, we showed that estrogenic compounds possess a low affinity and are present at high concentration. Finally, we used immobilized recombinant ER-αto separate ligands for ER and AhR that are present in river sediments. Immobilized ER-α, which does not retain dioxin-like compounds, enabled us to isolate and concentrate ER ligands to facilitate their further analysis. PMID:15743715

  3. Aromatase inhibiting and combined estrogenic effects of parabens and estrogenic effects of other additives in cosmetics

    SciTech Connect

    Meeuwen, J.A. van Son, O. van; Piersma, A.H.; Jong, P.C. de; Berg, M. van den

    2008-08-01

    There is concern widely on the increase in human exposure to exogenous (anti)estrogenic compounds. Typical are certain ingredients in cosmetic consumer products such as musks, phthalates and parabens. Monitoring a variety of human samples revealed that these ingredients, including the ones that generally are considered to undergo rapid metabolism, are present at low levels. In this in vitro research individual compounds and combinations of parabens and endogenous estradiol (E{sub 2}) were investigated in the MCF-7 cell proliferation assay. The experimental design applied a concentration addition model (CA). Data were analyzed with the estrogen equivalency (EEQ) and method of isoboles approach. In addition, the catalytic inhibitory properties of parabens on an enzyme involved in a rate limiting step in steroid genesis (aromatase) were studied in human placental microsomes. Our results point to an additive estrogenic effect in a CA model for parabens. In addition, it was found that parabens inhibit aromatase. Noticeably, the effective levels in both our in vitro systems were far higher than the levels detected in human samples. However, estrogenic compounds may contribute in a cumulative way to the circulating estrogen burden. Our calculation for the extra estrogen burden due to exposure to parabens, phthalates and polycyclic musks indicates an insignificant estrogenic load relative to the endogenous or therapeutic estrogen burden.

  4. Aromatase inhibiting and combined estrogenic effects of parabens and estrogenic effects of other additives in cosmetics.

    PubMed

    van Meeuwen, J A; van Son, O; Piersma, A H; de Jong, P C; van den Berg, M

    2008-08-01

    There is concern widely on the increase in human exposure to exogenous (anti)estrogenic compounds. Typical are certain ingredients in cosmetic consumer products such as musks, phthalates and parabens. Monitoring a variety of human samples revealed that these ingredients, including the ones that generally are considered to undergo rapid metabolism, are present at low levels. In this in vitro research individual compounds and combinations of parabens and endogenous estradiol (E(2)) were investigated in the MCF-7 cell proliferation assay. The experimental design applied a concentration addition model (CA). Data were analyzed with the estrogen equivalency (EEQ) and method of isoboles approach. In addition, the catalytic inhibitory properties of parabens on an enzyme involved in a rate limiting step in steroid genesis (aromatase) were studied in human placental microsomes. Our results point to an additive estrogenic effect in a CA model for parabens. In addition, it was found that parabens inhibit aromatase. Noticeably, the effective levels in both our in vitro systems were far higher than the levels detected in human samples. However, estrogenic compounds may contribute in a cumulative way to the circulating estrogen burden. Our calculation for the extra estrogen burden due to exposure to parabens, phthalates and polycyclic musks indicates an insignificant estrogenic load relative to the endogenous or therapeutic estrogen burden.

  5. Functional significance of the rapid regulation of brain estrogens: Where do the estrogens come from?

    PubMed Central

    Cornil, Charlotte A.; Ball, Gregory F.; Balthazart, Jacques

    2012-01-01

    Estrogens exert a wide variety of actions on reproductive and non-reproductive functions. These effects are mediated by slow and long lasting genomic as well as rapid and transient non-genomic mechanisms. Besides the host of studies demonstrating the role of genomic actions at the physiological and behavioral level, mounting evidence highlights the functional significance of non-genomic effects. However, the source of the rapid changes in estrogen availability that are necessary to sustain their fast actions is rarely questioned. For example, the rise of plasma estrogens at pro-estrus that represents one of the fastest documented changes in plasma estrogen concentration appears too slow to explain these actions. Alternatively, estrogen can be synthesized in the brain by the enzyme aromatase providing a source of locally high concentrations of the steroid. Furthermore, recent studies demonstrate that brain aromatase can be rapidly modulated by afferent inputs, including glutamatergic afferents. A role for rapid changes in estrogen production in the central nervous system is supported by experiments showing that acute aromatase inhibition affects nociception as well as male sexual behavior and that preoptic aromatase activity is rapidly (within min) modulated following mating. Such mechanisms thus fulfill the gap existing between the fast actions of estrogen and their mode of production and open new avenues for the understanding of estrogenic effects on the brain. PMID:16978590

  6. DNA adduct-induced stabilization of slipped frameshift intermediates within repetitive sequences: implications for mutagenesis.

    PubMed Central

    Garcia, A; Lambert, I B; Fuchs, R P

    1993-01-01

    Chemical carcinogens such as the aromatic amide 2-acetylaminofluorene (AAF) are known to induce -1 frameshift mutation hotspots at repetitive sequences. This mutagenesis pathway was suggested to involve slipped intermediates formed during replication. To investigate the stability and structure of such intermediates we have constructed DNA duplexes containing single AAF adducts within a run of three guanine residues. The strand complementary to that bearing the AAF adducts contained either the wild-type sequence (homoduplexes) or lacked one cytosine directly opposite the run of guanines containing the AAF adduct and thus modeled the putative slipped mutagenic intermediates (SMIs). The melting temperature of AAF-modified homoduplexes or the unmodified SMI was reduced by approximately 10 degrees C relative to the unmodified homoduplex. Surprisingly, AAF adducts stabilized the SMIs as evidenced by an increase in melting temperature to a level approaching that of the unmodified homoduplex. The chemical probes hydroxylamine and bromoacetaldehyde were strongly reactive toward cytosine residues opposite the adduct in AAF-modified homoduplexes, indicating adduct-induced denaturation. In contrast, no cytosine reactivities were observed in the AAF-modified SMIs, suggesting that the two cytosines were paired with unmodified guanines. Use of diethyl pyrocarbonate to probe the guanine residues showed that all three guanines in the unmodified SMI adopted a transient single-stranded state which was delocalized along the repetitive sequence. However, when an AAF adduct was present, reduced diethyl pyrocarbonate reactivity at guanines adjacent to the adduct in AAF-modified SMIs reflected localization of the bulge to the adducted base. Our results suggest that AAF exerts a local denaturing and destabilizing effect within the homoduplex which is alleviated by the formation of a bulge. The stabilization by the AAF adduct of the SMIs may contribute to the dramatic increase in -1

  7. Lack of Involvement of CEP Adducts in TLR Activation and in Angiogenesis

    PubMed Central

    Gounarides, John; Cobb, Jennifer S.; Zhou, Jing; Cook, Frank; Yang, Xuemei; Yin, Hong; Meredith, Erik; Rao, Chang; Huang, Qian; Xu, YongYao; Anderson, Karen; De Erkenez, Andrea; Liao, Sha-Mei; Crowley, Maura; Buchanan, Natasha; Poor, Stephen; Qiu, Yubin; Fassbender, Elizabeth; Shen, Siyuan; Woolfenden, Amber; Jensen, Amy; Cepeda, Rosemarie; Etemad-Gilbertson, Bijan; Giza, Shelby; Mogi, Muneto; Jaffee, Bruce; Azarian, Sassan

    2014-01-01

    Proteins that are post-translationally adducted with 2-(ω-carboxyethyl)pyrrole (CEP) have been proposed to play a pathogenic role in age-related macular degeneration, by inducing angiogenesis in a Toll Like Receptor 2 (TLR2)-dependent manner. We have investigated the involvement of CEP adducts in angiogenesis and TLR activation, to assess the therapeutic potential of inhibiting CEP adducts and TLR2 for ocular angiogenesis. As tool reagents, several CEP-adducted proteins and peptides were synthetically generated by published methodology and adduction was confirmed by NMR and LC-MS/MS analyses. Structural studies showed significant changes in secondary structure in CEP-adducted proteins but not the untreated proteins. Similar structural changes were also observed in the treated unadducted proteins, which were treated by the same adduction method except for one critical step required to form the CEP group. Thus some structural changes were unrelated to CEP groups and were artificially induced by the synthesis method. In biological studies, the CEP-adducted proteins and peptides failed to activate TLR2 in cell-based assays and in an in vivo TLR2-mediated retinal leukocyte infiltration model. Neither CEP adducts nor TLR agonists were able to induce angiogenesis in a tube formation assay. In vivo, treatment of animals with CEP-adducted protein had no effect on laser-induced choroidal neovascularization. Furthermore, in vivo inactivation of TLR2 by deficiency in Myeloid Differentiation factor 88 (Myd88) had no effect on abrasion-induced corneal neovascularization. Thus the CEP-TLR2 axis, which is implicated in other wound angiogenesis models, does not appear to play a pathological role in a corneal wound angiogenesis model. Collectively, our data do not support the mechanism of action of CEP adducts in TLR2-mediated angiogenesis proposed by others. PMID:25343517

  8. Experimental and computational evidence for the mechanism of intradiol catechol dioxygenation by non-heme iron(III) complexes.

    PubMed

    Jastrzebski, Robin; Quesne, Matthew G; Weckhuysen, Bert M; de Visser, Sam P; Bruijnincx, Pieter C A

    2014-11-24

    Catechol intradiol dioxygenation is a unique reaction catalyzed by iron-dependent enzymes and non-heme iron(III) complexes. The mechanism by which these systems activate dioxygen in this important metabolic process remains controversial. Using a combination of kinetic measurements and computational modelling of multiple iron(III) catecholato complexes, we have elucidated the catechol cleavage mechanism and show that oxygen binds the iron center by partial dissociation of the substrate from the iron complex. The iron(III) superoxide complex that is formed subsequently attacks the carbon atom of the substrate by a rate-determining C-O bond formation step. PMID:25322920

  9. Catechol-based layer-by-layer assembly of composite coatings: a versatile platform to hierarchical nano-materials.

    PubMed

    Wang, C X; Braendle, A; Menyo, M S; Pester, C W; Perl, E E; Arias, I; Hawker, C J; Klinger, D

    2015-08-21

    Inspired by the marine mussel's ability to adhere to surfaces underwater, an aqueous catechol-based dip coating platform was developed. Using a catechol-functionalized polyacrylamide binder in combination with inorganic nanoparticles enables the facile fabrication of robust composite coatings via a layer-by-layer process. This modular assembly of well-defined building blocks provides a versatile alternative to electrostatic driven approaches with layer thickness and refractive indices being readily tunable. The platform nature of this approach enables the fabrication of hierarchically ordered nano-materials such as Bragg stacks.

  10. Application of p-toluidine in chromogenic detection of catechol and protocatechuate, diphenolic intermediates in catabolism of aromatic compounds

    SciTech Connect

    Parke, D. )

    1992-08-01

    In the presence of p-toluidine and iron, protocatechuate and catechols yield color. Inclusion of p-toluidine in media facilities the screening of microbial strains for alterations affecting aromatic catabolism. Such strains include mutants affected in the expression of oxygenases and Escherichia coli colonies carrying cloned or subcloned aromatic catabolic genes which encode enzymes giving rise to protocatechuate or catechol. The diphenolic detection system can also be applied to the creation of vectors relying on insertion of cloned DNA into one of the latter marker genes.

  11. Turned head--adducted hip--truncal curvature syndrome.

    PubMed Central

    Hamanishi, C; Tanaka, S

    1994-01-01

    One hundred and eight neonates and infants who showed the clinical triad of a head turned to one side, adduction contracture of the hip joint on the occipital side of the turned head, and truncal curvature, which we named TAC syndrome, were studied. These cases included seven with congenital and five with late infantile dislocations of the hip joint and 14 who developed muscular torticollis. Forty one were among 7103 neonates examined by one of the authors. An epidemiological analysis confirmed the aetiology of the syndrome to be environmental. The side to which the head was turned and that of the adducted hip contracture showed a high correlation with the side of the maternal spine on which the fetus had been lying. TAC syndrome is an important asymmetrical deformity that should be kept in mind during neonatal examination, and may be aetiologically related to the unilateral dislocation of the hip joint, torticollis, and infantile scoliosis which develop after a vertex presentation. Images PMID:8048823

  12. Effect of vaginal estrogen on pessary use

    PubMed Central

    Dessie, Sybil G.; Armstrong, Katherine; Modest, Anna M.; Hacker, Michele R.

    2016-01-01

    Introduction and hypothesis Many providers recommend concurrent estrogen therapy with pessary use to limit complications; however, limited data exist to support this practice. We hypothesized that vaginal estrogen supplementation decreases incidence of pessary-related complications and discontinuation. Methods We performed a retrospective cohort study of women who underwent a pessary fitting from 1 January 2007 through 1 September 2013 at one institution; participants were identified by billing code and were eligible if they were post-menopausal and had at least 3 months of pessary use and 6 months of follow-up. All tests were two sided, and P values < 0.05 were considered statistically significant. Results Data from 199 women were included; 134 used vaginal estrogen and 65 did not. Women who used vaginal estrogen had a longer median follow-up time (29.5 months) compared with women who did not (15.4 months) and were more likely to have at least one pessary check (98.5 % vs 86.2 %, P < 0.001). Those in the estrogen group were less likely to discontinue using their pessary (30.6 % vs 58.5 %, P < 0.001) and less likely to develop increased vaginal discharge than women who did not [hazard ratio (HR) 0.31, 95 % confidence interval (CI) 0.17–0.58]. Vaginal estrogen was not protective against erosions (HR 0.93, 95 % CI 0.54–1.6) or vaginal bleeding (HR 0.78, 95 % CI 0.36–1.7). Conclusions Women who used vaginal estrogen exhibited a higher incidence of continued pessary use and lower incidence of increased vaginal discharge than women who did not. PMID:26992727

  13. Estrogenic Compounds, Estrogen Receptors and Vascular Cell Signaling in the Aging Blood Vessels

    PubMed Central

    Smiley, Dia A.; Khalil, Raouf A.

    2010-01-01

    The cardiovascular benefits of menopausal hormone therapy (MHT) remain controversial. The earlier clinical observations that cardiovascular disease (CVD) was less common in MHT users compared to non-users suggested cardiovascular benefits of MHT. Also, experimental studies have identified estrogen receptors ERα, ERβ and GPR30, which mediate genomic or non-genomic effects in vascular endothelium, smooth muscle, and extracellular matrix (ECM). However, data from randomized clinical trials (RCTs), most notably the Women's Health Initiative (WHI) study, have challenged the cardiovascular benefits and highlighted adverse cardiovascular events with MHT. The discrepancies have been attributed to the design of RCTs, the subjects' advanced age and preexisting CVD, and the form of estrogen used. The discrepancies may also stem from age-related changes in vascular ER amount, distribution, integrity, and post-receptor signaling pathways as well as structural changes in the vasculature. Age-related changes in other sex hormones such as testosterone may also alter the hormonal environment and influence the cardiovascular effects of estrogen. Investigating the chemical properties, structure-activity relationship and pharmacology of natural and synthetic estrogens should improve the effectiveness of conventional MHT. Further characterization of phytoestrogens, selective estrogen-receptor modulators (SERMs), and specific ER agonists may provide substitutes to conventional MHT. Conditions with excess or low estrogen levels such as polycystic ovary syndrome (PCOS) and Turner syndrome may provide insight into the development and regulation of ER and the mechanisms of aberrant estrogen-ER interactions. The lessons learned from previous RCTs have led to more directed studies such as the Kronos Early Estrogen Prevention Study (KEEPS). Careful design of experimental models and RCTs, coupled with the development of specific ER modulators, hold the promise of improving the actions of

  14. Suicide inactivation of catechol 2,3-dioxygenase from Pseudomonas putida mt-2 by 3-halocatechols

    SciTech Connect

    Bartels, I.; Knackmuss, H.J.; Reineke, W.

    1984-03-01

    The inactivation of catechol 2,3-dioxygenase from Pseudomonas putida mt-2 by 3-chloro- and 3-fluorocatechol and the iron-chelating agent Tiron (catechol-3,5-disulfonate) was studied. Whereas inactivation by Tiron is an oxygen-independent and mostly reversible process, inactivation by the 3-halocatechols was only observed in the presence of oxygen and was largely irreversible. The rate constants for inactivation (K/sub 2/) were 1.62 x 10/sup -3/ sec/sup -1/ for 3-chlorocatechol and 2.38 x 10/sup -3/ sec/sup -1/ for 3-fluorocatechol. The inhibitor constants (K/sub i/) were 23 ..mu..M for 3-chlorocatechol and 17 ..mu..M for 3-fluorocatechol. The kinetic data for 3-fluorocatechol could only be obtained in the presence of 2-mercaptoethanol. Besides inactivated enzyme, some 2-hydroxyhexa-2,4-dienoic acid as the actual suicide product of meta-cleavage. A side product of 3-fluorocatechol cleavage is a yellow compound with the spectral characteristics of a 2-hydroxy-6-oxohexa-2,4-dienoci acid indicating 1,6-cleavage. Rates of inactivation by 3-fluorocatechol were reduced in the presence of superoxide dismutase, catalase, formate, and mannitol, which implies that superoxide anion, hydrogen peroxide, and hydroxyl radical exhibit additional inactivation. 64 references.

  15. Mechanics of metal-catecholate complexes: The roles of coordination state and metal types

    PubMed Central

    Xu, Zhiping

    2013-01-01

    There have been growing evidences for the critical roles of metal-coordination complexes in defining structural and mechanical properties of unmineralized biological materials, including hardness, toughness, and abrasion resistance. Their dynamic (e.g. pH-responsive, self-healable, reversible) properties inspire promising applications of synthetic materials following this concept. However, mechanics of these coordination crosslinks, which lays the ground for predictive and rational material design, has not yet been well addressed. Here we present a first-principles study of representative coordination complexes between metals and catechols. The results show that these crosslinks offer stiffness and strength near a covalent bond, which strongly depend on the coordination state and type of metals. This dependence is discussed by analyzing the nature of bonding between metals and catechols. The responsive mechanics of metal-coordination is further mapped from the single-molecule level to a networked material. The results presented here provide fundamental understanding and principles for material selection in metal-coordination-based applications. PMID:24107799

  16. Linkage between Catecholate Siderophores and the Multicopper Oxidase CueO in Escherichia coli

    PubMed Central

    Grass, Gregor; Thakali, Keshari; Klebba, Phillip E.; Thieme, Daniel; Müller, Axel; Wildner, Günter F.; Rensing, Christopher

    2004-01-01

    The multicopper oxidase CueO had previously been demonstrated to exhibit phenoloxidase activity and was implicated in intrinsic copper resistance in Escherichia coli. Catecholates can potentially reduce Cu(II) to the prooxidant Cu(I). In this report we provide evidence that CueO protects E. coli cells by oxidizing enterobactin, the catechol iron siderophore of E. coli, in the presence of copper. In vitro, a mixture of enterobactin and copper was toxic for E. coli cells, but the addition of purified CueO led to their survival. Deletion of fur resulted in copper hypersensitivity that was alleviated by additional deletion of entC, preventing synthesis of enterobactin. In addition, copper added together with 2,3-dihydroxybenzoic acid or enterobactin was able to induce a Φ(cueO-lacZ) operon fusion more efficiently than copper alone. The reaction product of the 2,3-dihydroxybenzoic acid oxidation by CueO that can complex Cu(II) ions was determined by gas chromatography-mass spectroscopy and identified as 2-carboxymuconate. PMID:15317788

  17. Crystal structures of the apo and holo form of rat catechol-O-methyltransferase.

    PubMed

    Tsuji, Eiichi; Okazaki, Kosuke; Isaji, Masayuki; Takeda, Kei

    2009-03-01

    Catechol-O-methyltransferase (COMT, EC 2.1.1.6) is a monomeric enzyme that catalyzes the transfer of a methyl group from S-adenosyl-l-methionine (AdoMet) to the phenolic oxygen of substituted catechols. Although the inhibitor recognition pattern and AdoMet site have already been studied crystallographically, structural information on the catalytic cycle of COMT has not yet been obtained. In this study, comparison of the co-factor and inhibitor-bound structures revealed that the Apo form of COMT shows a conformational change and there was no cleft corresponding to the AdoMet-binding site; the overall structure was partially open form and the substrate recognition site was not clearly defined. The Holo form of COMT was similar to the quaternary structure except for the beta6-beta7 and alpha2-alpha3 ligand recognition loops. These conformational changes provide a deeper insight into the structural events occurring in reactions catalyzed by AdoMet.

  18. Facile fabrication of gold nanoparticle on zein ultrafine fibers and their application for catechol biosensor

    NASA Astrophysics Data System (ADS)

    Chen, Xiaodong; Li, Dawei; Li, Guohui; Luo, Lei; Ullah, Naseeb; Wei, Qufu; Huang, Fenglin

    2015-02-01

    A novel laccase biosensor based on a new composite of laccase-gold nanoparticles (Au NPs)-crosslinked zein ultrafine fibers (CZUF) has been fabricated for catechol determination in real solution samples. Firstly, crosslinked zein ultrafine fibers containing gold nanoparticles (A-CZUF) were prepared by combining electrospinning and one-step reduction method using poly(ethyleneimine) (PEI) as reducing and crosslinking agent. A smooth morphology and relative average distribution of A-CZUF were depicted by scanning electron microscope (SEM) and transmission electron microscopy (TEM). The Fourier transform infrared spectroscopy (FT-IR) analysis indicated that PEI molecules attached to the surface of the zein ultrafine fibers via the reaction of functional groups between PEI and glyoxal. The results obtained from ultraviolet visible spectroscopy (UV-vis spectroscopy), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA) for A-CZUF confirmed the existence of Au NPS coated on the surface of CZUF. Square wave voltammetry (SWV) and cyclic voltammetry (CV) were used to detect the electrochemical performance of the proposed biosensor. The results demonstrated that this biosensor possessed a high sensitive detection to catechol, which was attributed to the direct electron transfer (DET) facilitated by Au NPs and high catalytic ability obtained from laccase. In addition, the proposed biosensor exhibited good reproducibility, stability and selectivity.

  19. Oxidative degradation and associated mineralization of catechol, hydroquinone and resorcinol catalyzed by birnessite.

    PubMed

    Chang Chien, S W; Chen, H L; Wang, M C; Seshaiah, K

    2009-02-01

    Abiotic degradation and mineralization of catechol, hydroquinone, and resorcinol catalyzed by birnessite (delta-MnO2) was investigated. Studies were carried out by monitoring changes of pE versus time and pH versus time of the reaction systems during the initial 10 h reaction period and release of CO2 and associated reactions at the end of a 90 h reaction period. The reactions under anoxic condition were compared with aeration condition. The reactions were carried out in suspensions at initial pH of 6.0 under air and N2 atmosphere at room temperature and free of microbial activity. These results indicated that kinetic-related changes of pE versus time and pH versus time were dependent on structural characteristics of phenolic compound and aeration or anoxic condition in the reaction system. The sequence of the mineralization of phenolic compounds catalyzed by delta-MnO2 in presence of air expressed by CO2 release was catechol > hydroquinone > or = resorcinol and the differences were significant. However, under an N2 atmosphere the amounts of CO2 released were drastically reduced with insignificant differences among the three reaction systems. Further, phenolic compound degradations, dissolved and adsorbed Mn, and oxidation state of Mn in delta-MnO2 were also determined to elucidate the catalytic efficacy mediated by both O2 and delta-MnO2 in the reaction systems.

  20. Degradation of Phenolic Compounds and Ring Cleavage of Catechol by Phanerochaete chrysosporium

    PubMed Central

    Leatham, Gary F.; Crawford, R. L.; Kirk, T. Kent

    1983-01-01

    POL-88, a mutant of the white-rot fungus Phanerochaete chrysosporium, was selected for diminished phenol-oxidizing enzyme activity. A wide variety of phenolic compounds were degraded by ligninolytic cultures of this mutant. With several o-diphenolic substrates, degradation intermediates were produced that had UV spectra consistent with muconic acids. Extensive spectrophotometric and polarographic assays failed to detect classical ring-cleaving dioxygenases in cell homogenates or in extracts from ligninolytic cultures. Even so, a sensitive carrier-trapping assay showed that intact cultures degraded [U-14C]catechol to [14C]muconic acid, establishing the presence of a system capable of 1,2-intradiol fission. Significant accumulation of [14C]muconic acid into carrier occurred only when evolution of 14CO2 from [14C]catechol was inhibited by treating cultures with excess nutrient nitrogen (e.g., l-glutamic acid) or with cycloheximide. l-Glutamic acid is known from past work to repress the ligninolytic system in P. chrysosporium and to mimic the effect of cycloheximide. The results here indicate, therefore, that the enzyme system responsible for degrading ring-cleavage products to CO2 turns over faster than does the system responsible for ring cleavage. PMID:16346340

  1. Human catechol-O-methyltransferase: Cloning and expression of the membrane-associated form

    SciTech Connect

    Bertocci, B.; Miggiano, V.; Da Prada, M.; Dembic, Z.; Lahm, H.W.; Malherbe, P. )

    1991-02-15

    A cDNA clone for human catechol-O-methyltransferase was isolated from a human hepatoma cell line (Hep G2) cDNA library by hybridization screening with a porcine cDNA probe. The cDNA clone was sequenced and found to have an insert of 1226 nucleotides. The deduced primary structure of hCOMT is composed of 271 amino acid residues with the predicted molecular mass of 30 kDa. At its N terminus it has a hydrophobic segment of 21 amino acid residues that may be responsible for insertion of hCOMT into the endoplasmic reticulum membrane. The primary structure of hCOMT exhibits high homology to the porcine partial cDNA sequence (93%). The deduced amino acid sequence contains two tryptic peptide sequences (T-22, T-33) found in porcine liver catechol-O-methyltransferase (CEMT). The coding region of hCOMT cDNA was placed under the control of the cytomegalovirus promoter to transfect human kidney 293 cells. The recombinant hCOMT was shown by immunoblot analysis to be mainly associated with the membrane fraction. RNA blot analysis revealed one COMT mRNA transcript of 1.4 kilobases in Hep G2 poly(A){sup +} RNA.

  2. Mechanics of metal-catecholate complexes: the roles of coordination state and metal types.

    PubMed

    Xu, Zhiping

    2013-10-10

    There have been growing evidences for the critical roles of metal-coordination complexes in defining structural and mechanical properties of unmineralized biological materials, including hardness, toughness, and abrasion resistance. Their dynamic (e.g. pH-responsive, self-healable, reversible) properties inspire promising applications of synthetic materials following this concept. However, mechanics of these coordination crosslinks, which lays the ground for predictive and rational material design, has not yet been well addressed. Here we present a first-principles study of representative coordination complexes between metals and catechols. The results show that these crosslinks offer stiffness and strength near a covalent bond, which strongly depend on the coordination state and type of metals. This dependence is discussed by analyzing the nature of bonding between metals and catechols. The responsive mechanics of metal-coordination is further mapped from the single-molecule level to a networked material. The results presented here provide fundamental understanding and principles for material selection in metal-coordination-based applications.

  3. Bio-inspired multifunctional catecholic assembly for photo-programmable biointerface.

    PubMed

    Huang, Chun-Jen; Wang, Lin-Chuan

    2015-10-01

    This article reports a novel multifunctional mussel-inspired zwitterionic catecholic assembly to form a photoresponsive biointerface. The assembly is the combination of the antifouling sulfobetaine and photocleavable o-nitrophenyl moieties into a molecule, becoming sulfobetaine nitrodopamine (SB-nDA). We demonstrated the formation of a compact thin SB-nDA film on TiO₂ by using the pH transition approach. The film thickness, surface wettability and elemental composition were characterized using ellipsometry, contact angle goniometer, atomic force microscopy and X-ray photoelectron spectroscopy, respectively. The SB-nDA thin films can effectively resist adhesion of both Gram-positive Staphylococcus epidermidis and Gram-negative Pseudomonas aeruginosa by more than 95% relative to bare TiO₂. Quartz crystal microbalance with dissipation (QCM-D) sensor was employed for protein fouling tests, showing the comparable antifouling property of SB-nDA with thiol- or silane-based surface ligands. More importantly, the spatiotemporal control over the bioinertness by UV irradiation has been studied with bacterial and protein adsorption. Therefore, the catecholic chemistry can be used for programmable tailoring of interfacial properties, permitting potential application in light-guided targeting for nanomedicine. PMID:26208296

  4. Specific plant DNA adducts as molecular biomarkers of genotoxic atmospheric environments.

    PubMed

    Weber-Lotfi, F; Obrecht-Pflumio, S; Guillemaut, P; Kleinpeter, J; Dietrich, A

    2005-03-01

    The general purpose of this study was to determine whether the formation of DNA addition products ('adducts') in plants could be a valuable biomarker of genotoxic air pollution. Plants from several species were exposed to ambient atmosphere at urban and suburban sites representative of different environmental conditions. The levels of NO2 and of the quantitatively major genotoxic air pollutants benzene, toluene, and xylene were monitored in parallel with plant exposure. DNA adducts were measured in bean (Phaseolus vulgaris), rye-grass (Lolium perenne), and tobacco (Nicotiana tabacum) seedlings by means of the [32P]-postlabeling method. Whereas, no correlation was found between the levels of the major genotoxic air pollutants and the total amounts of DNA adducts, individual analyses revealed site-specific and plant species-specific adduct responses, both at the qualitative and quantitative level. Among these, the amount of a specific rye-grass DNA adduct (rgs1) correlated with benzene/toluene/xylene levels above a threshold. For further characterization, rye-grass seedlings were treated in controlled conditions with benzene, toluene, xylene or their derivatives. On the other hand, in vitro DNA adduct formation assays were developed involving benzene, toluene, xylene, or their derivatives, and plant microsomes or purified peroxidase. Although in some cases, these approaches produced specific adduct responses, they failed to generate the rgs1 DNA adduct, which appeared to be characteristic for on-site test-plant exposure. Our studies have thus identified an interesting candidate for further analysis of environmental biomarkers of genotoxicity.

  5. Malondialdehyde and 4-hydroxynonenal protein adducts in plasma and liver of rats with iron overload.

    PubMed Central

    Houglum, K; Filip, M; Witztum, J L; Chojkier, M

    1990-01-01

    In hepatic iron overload, iron-catalyzed lipid peroxidation has been implicated in the mechanisms of hepatocellular injury. Lipid peroxidation may produce reactive aldehydes such as malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), which may form aldehyde-protein adducts. We investigated whether lipid peroxidation occurred in rats fed a diet containing 3% carbonyl iron for 5-13 wk, and if this resulted in the formation of MDA- and 4-HNE- protein adducts. Chronic iron feeding resulted in hepatic iron overload (greater than 10-fold) and concomitantly induced a 2-fold increase in hepatic lipid peroxidation. Using an antiserum specific for MDA-lysine protein adducts, we demonstrated by immunohistochemistry the presence of aldehyde-protein adducts in the cytosol of periportal hepatocytes, which co-localized with iron. In addition, MDA- and 4-HNE-lysine adducts were found in plasma proteins of animals with iron overload. Only MDA adducts were detected in albumin, while other plasma proteins including a approximately 120-kD protein had both MDA and 4-HNE adducts. In this animal model of hepatic iron overload, injury occurs primarily in periportal hepatocytes, where MDA-lysine protein adducts and excess iron co-localized. Images PMID:2123889

  6. 40 CFR 721.3700 - Fatty acid, ester with styrenated phenol, ethylene oxide adduct.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... phenol, ethylene oxide adduct. 721.3700 Section 721.3700 Protection of Environment ENVIRONMENTAL..., ethylene oxide adduct. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as fatty acid, ester with styrenated phenol, ethylene...

  7. 40 CFR 721.3700 - Fatty acid, ester with styrenated phenol, ethylene oxide adduct.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... phenol, ethylene oxide adduct. 721.3700 Section 721.3700 Protection of Environment ENVIRONMENTAL..., ethylene oxide adduct. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as fatty acid, ester with styrenated phenol, ethylene...

  8. 40 CFR 721.3700 - Fatty acid, ester with styrenated phenol, ethylene oxide adduct.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... phenol, ethylene oxide adduct. 721.3700 Section 721.3700 Protection of Environment ENVIRONMENTAL..., ethylene oxide adduct. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as fatty acid, ester with styrenated phenol, ethylene...

  9. gamma. Irradiation induced formation of PCB-solvent adducts in aliphatic solvents

    SciTech Connect

    Lepine, F.; Milot, S.; Gagne, N. )

    1990-09-01

    {gamma}Irradiation induced formation of PCB-solvent adducts was investigated as a model for PCB residues in irradiated food. Formation of cyclohexyl adducts of PCBs was found to be significant when pure PCB congeners and Aroclor mixture were irradiated in cyclohexane and cyclohexene. Reaction pathways were investigated, and the effects of oxygen and electron scavenger were studied.

  10. A hydrogen bond scaffold supported synthetic heme Fe(III)-O2(-) adduct.

    PubMed

    Mittra, Kaustuv; Chatterjee, Sudipta; Samanta, Subhra; Sengupta, Kushal; Bhattacharjee, Hridaynath; Dey, Abhishek

    2012-11-01

    A hydrogen bonded heme-Fe(III)-O(2)(-) adduct is stabilized and characterized using resonance Raman and EPR spectroscopy. The low O-O vibrations of this complex are quite different from those reported for other heme-Fe(III)-O(2)(-) adducts.

  11. Cyclooctyne [60]fullerene hexakis adducts: a globular scaffold for copper-free click chemistry.

    PubMed

    Ramos-Soriano, Javier; Reina, José J; Pérez-Sánchez, Alfonso; Illescas, Beatriz M; Rojo, Javier; Martín, Nazario

    2016-08-18

    The synthesis of a new highly symmetric hexakis adduct of C60 appended with 12 cyclooctyne moieties has been carried out. This compound has been used for the copper-free strain-promoted cycloaddition reaction to a series of azides with excellent yields. This strategy for the obtention of clicked adducts of [60]fullerene is of special interest for biological applications. PMID:27492263

  12. Effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin administration and high-fat diet on the body weight and hepatic estrogen metabolism in female C3H/HeN mice

    SciTech Connect

    Zhu Baoting Gallo, Michael A. Burger, Conney W.; Meeker, Robert J.; Cai, May Xiaoxin; Xu Shiyao; Conney, Allan H.

    2008-01-15

    We studied the effect of administration of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) by i.p. injection once every 2 weeks in combination with a high-fat (HF) diet for 8 or 16 weeks on the body and organ weight changes as well as on the hepatic enzyme activity for estrogen metabolism in C3H/HeN female mice. Administration of TCDD at 100 {mu}g/kg b.w. once every 2 weeks for 8 weeks increased the body weight by 46% in the HF diet-fed animals, but not in the regular diet-fed animals. This is the first observation suggesting that TCDD at a high dose (100 {mu}g/kg b.w.), but not at lower doses (1 or 10 {mu}g/kg b.w.), may have a strong obesity-inducing effect in C3H/HeN mice fed an HF diet. While TCDD increased liver weight and decreased thymus weight in animals, these effects were enhanced by feeding animals an HF diet. Metabolism studies showed that TCDD administration for 8 or 16 weeks increased the liver microsomal activity for the 2- and 4-hydroxylation of 17{beta}-estradiol in animals fed a control diet, but surprisingly not in animals fed an HF diet. Treatment with TCDD dose-dependently increased the hepatic activity for the O-methylation of catechol estrogens in both control and HF diet-fed animals, and it also decreased the levels of liver microsomal sulfatase activity for hydrolysis of estrone-3-sulfate. TCDD did not significantly affect the hepatic enzyme activity for the glucuronidation or esterification of endogenous estrogens. It is suggested that enhanced metabolic inactivation of endogenous estrogens by hepatic estrogen-metabolizing enzymes in TCDD-treated, control diet-fed animals contributes importantly to the reduced incidence of estrogen-associated tumors in animals treated with TCDD.

  13. Quantitation of 4,4′-methylene diphenyl diisocyanate human serum albumin adducts

    PubMed Central

    Luna, Leah G.; Green, Brett J.; Zhang, Fagen; Arnold, Scott M.; Siegel, Paul D.; Bartels, Michael J.

    2016-01-01

    4,4′-Methylene diphenyl diisocyanate (herein 4,4′-MDI) is used in the production of polyurethane foams, elastomers, coatings, adhesives and the like for a wide range of commercial products. Occupational exposure to MDI levels above current airborne exposure limits can elicit immune mediated hypersensitivity reactions such as occupational asthma in sensitive individuals. To accurately determine exposure, there has been increasing interest in developing analytical methods to measure internal biomarkers of exposure to MDI. Previous investigators have reported methodologies for measuring MDI diamine metabolites and MDI-Lysine (4,4′-MDI-Lys) adducts. The purpose of this study was to develop and validate an ultra performance liquid chromatography isotope dilution tandem mass spectrometry (UPLC-ID/MS/MS) quantitation method via a signature peptide approach to enable biomonitoring of 4,4′-MDI adducted to human serum albumin (HSA) in plasma. A murine, anti-4,4′-MDI monoclonal IgM antibody was bound to magnetic beads and utilized for enrichment of the MDI adducted HSA. Following enrichment, trypsin digestion was performed to generate the expected 414 site (primary site of adduction) 4,4′-MDI-adducted HSA signature peptide that was quantified by UPLC-ID/MS/MS. An Agilent 6530 UPLC/quadrupole time of flight MS (QTOF) system was utilized for intact adducted protein analysis and an Agilent 6490 UPLC/MS/MS system operated in multiple reaction monitoring (MRM) mode was utilized for quantification of the adducted signature peptide biomarker both for in chemico and worker serum samples. Worker serum samples were initially screened utilizing the previously developed 4,4′-MDI-Lys amino acid method and results showed that 12 samples were identified as quantifiable for 4,4′-MDI-Lys adducts. The signature peptide adduct approach was applied to the 12 worker samples identified as quantifiable for 4,4′-MDI-Lys adducts. Results indicated no positive results were obtained

  14. Is Estrogen a Therapeutic Target for Glaucoma?

    PubMed

    Dewundara, Samantha S; Wiggs, Janey L; Sullivan, David A; Pasquale, Louis R

    2016-01-01

    This article's objective is to provide an overview of the association between estrogen and glaucoma. A literature synthesis was conducted of articles published in peer-reviewed journals screened through May 5, 2015, using the PubMed database. Keywords used were "estrogen and glaucoma," "reproductive factors and glaucoma," and "estrogen, nitric oxide and eye." Forty-three journal articles were included. Results indicated that markers for lifetime estrogen exposure have been measured by several studies and show that the age of menarche onset, oral contraceptive (OC) use, bilateral oophorectomy, age of menopause onset and duration between menarche to menopause are associated with primary open-angle glaucoma (POAG) risk. The Blue Mountain Eye Study found a significantly increased POAG risk with later (>13 years) compared with earlier (≤12 years) age of menarche. Nurses' Health Study (NHS) investigators found that OC use of greater than 5 years was associated with a 25% increased risk of POAG. The Mayo Clinic Cohort Study of Oophorectomy and Aging found that women who underwent bilateral oophorectomy before age 43 years had an increased risk of glaucoma. The Rotterdam Study found that women who went through menopause before reaching the age of 45 years had a higher risk of open-angle glaucoma (2.6-fold increased risk), while the NHS showed a reduced risk of POAG among women older than 65 who entered menopause after age ≥ 54 years. Increased estrogen states may confer a reduced risk of glaucoma or glaucoma-related traits such as reduced intraocular pressure (IOP). Pregnancy, a hyperestrogenemic state, is associated with decreased IOP during the third trimester. Though the role of postmenopausal hormone (PMH) use in the reduction of IOP is not fully conclusive, PMH use may reduce the risk of POAG. From a genetic epidemiologic perspective, estrogen metabolic pathway single nucleotide polymorphisms (SNPs) were associated with POAG in women and polymorphisms in

  15. Identification of polycyclic aromatic hydrocarbon metabololites and DNA adducts in mixtures using fluorescence line narrowing spectrometry

    SciTech Connect

    Sanders, M.J.; Cooper, R.S.; Jankowiak, R.; Small, G.J.; Heisig, V.; Jeffrey, A.M.

    1986-04-01

    Fluorescence line narrowing spectrometry is applied to five modifications of DNA (intact adducts) formed from diol epoxides of benzo(a)pyrene, chrysene, 5-methylchrysene, and benz(a)anthracene. The direct identification of all five adducts in a laboratory mixture is accomplished. In addition, a mixture of six corresponding metabolites plus the DNA adducts from benzo(a)pyrene and 5-methylchrysene is resolved. Each adduct can be distinguished from its corresponding tetrol metabolite. Utilization of an intensified diode array-optical multichannel analyzer provides detection of the adduct from benzo(a)pyrene with a S/N approx. 150 for a damage level of approx. 5 bases in 10/sup 6/. 25 references, 7 figures.

  16. DNA adducts in marine mussel and fresh water fishes living in polluted and unpolluted environments

    SciTech Connect

    Kurelec, B.; Checko, M.; Krca, S.; Garg, A.; Gupta, R.C. Baylor College of Medicine, Houston, TX )

    1988-09-01

    {sup 32}P-postlabeling analysis of DNA adducts in the digestive gland of marine mussel Mytilus galloprovincialis from polluted and unpolluted sites near Rovinj, Northern Adriatic, revealed that majority of adducts are caused by natural environmental factors rather than by man-made chemicals. The only pollutant-specific adducts were observed in a mussel exposed to seawater experimentally polluted with aminofluorene, and in a population of mussel living at a site heavily polluted with a waste waters of an oil refinery. Fresh water fish species Leuciscus cephalus, Barbus barbus, Abramis brama and Rutilus pigus virgo living in a polluted Sava River, Yugoslavia, or in its unpolluted tributary Korana River, have induced in their livers qualitatively identical and quantitatively similar DNA adducts. These DNA adducts had a species-specific patterns and their appearance was seasonally-dependent.

  17. MRN, CtIP, and BRCA1 mediate repair of topoisomerase II–DNA adducts

    PubMed Central

    Aparicio, Tomas; Baer, Richard; Gottesman, Max

    2016-01-01

    Repair of DNA double-strand breaks (DSBs) with complex ends poses a special challenge, as additional processing is required before DNA ligation. For example, protein–DNA adducts must be removed to allow repair by either nonhomologous end joining or homology-directed repair. Here, we investigated the processing of topoisomerase II (Top2)–DNA adducts induced by treatment with the chemotherapeutic agent etoposide. Through biochemical analysis in Xenopus laevis egg extracts, we establish that the MRN (Mre11, Rad50, and Nbs1) complex, CtIP, and BRCA1 are required for both the removal of Top2–DNA adducts and the subsequent resection of Top2-adducted DSB ends. Moreover, the interaction between CtIP and BRCA1, although dispensable for resection of endonuclease-generated DSB ends, is required for resection of Top2-adducted DSBs, as well as for cellular resistance to etoposide during genomic DNA replication. PMID:26880199

  18. Using a customized DNA microarray for expression profiling of the estrogen-responsive genes to evaluate estrogen activity among natural estrogens and industrial chemicals.

    PubMed Central

    Terasaka, Shunichi; Aita, Yukie; Inoue, Akio; Hayashi, Shinichi; Nishigaki, Michiko; Aoyagi, Kazuhiko; Sasaki, Hiroki; Wada-Kiyama, Yuko; Sakuma, Yasuo; Akaba, Shuichi; Tanaka, Junko; Sone, Hideko; Yonemoto, Junzo; Tanji, Masao; Kiyama, Ryoiti

    2004-01-01

    We developed a DNA microarray to evaluate the estrogen activity of natural estrogens and industrial chemicals. Using MCF-7 cells, we conducted a comprehensive analysis of estrogen-responsive genes among approximately 20,000 human genes. On the basis of reproducible and reliable responses of the genes to estrogen, we selected 172 genes to be used for developing a customized DNA microarray. Using this DNA microarray, we examined estrogen activity among natural estrogens (17beta-estradiol, estriol, estrone, genistein), industrial chemicals (diethylstilbestrol, bisphenol A, nonylphenol, methoxychlor), and dioxin. We obtained results identical to those for other bioassays that are used for detecting estrogen activity. On the basis of statistical correlations analysis, these bioassays have shown more sensitivity for dioxin and methoxychlor. PMID:15159206

  19. Estrogenicity of glabridin in Ishikawa cells.

    PubMed

    Su Wei Poh, Melissa; Voon Chen Yong, Phelim; Viseswaran, Navaratnam; Chia, Yoke Yin

    2015-01-01

    Glabridin is an isoflavan from licorice root, which is a common component of herbal remedies used for treatment of menopausal symptoms. Past studies have shown that glabridin resulted in favorable outcome similar to 17β-estradiol (17β-E2), suggesting a possible role as an estrogen replacement therapy (ERT). This study aims to evaluate the estrogenic effect of glabridin in an in-vitro endometrial cell line -Ishikawa cells via alkaline phosphatase (ALP) assay and ER-α-SRC-1-co-activator assay. Its effect on cell proliferation was also evaluated using Thiazoyl blue tetrazolium bromide (MTT) assay. The results showed that glabridin activated the ER-α-SRC-1-co-activator complex and displayed a dose-dependent increase in estrogenic activity supporting its use as an ERT. However, glabridin also induced an increase in cell proliferation. When glabridin was treated together with 17β-E2, synergistic estrogenic effect was observed with a slight decrease in cell proliferation as compared to treatment by 17β-E2 alone. This suggest that the combination might be better suited for providing high estrogenic effects with lower incidences of endometrial cancer that is associated with 17β-E2. PMID:25816349

  20. Estrogen receptors and human disease: an update

    PubMed Central

    Burns, Katherine A.

    2016-01-01

    A myriad of physiological processes in mammals are influenced by estrogens and the estrogen receptors (ERs), ERα and ERβ. As we reviewed previously, given the widespread role for estrogen in normal human physiology, it is not surprising that estrogen is implicated in the development or progression of a number of diseases. In this review, we are giving a 5-year update of the literature regarding the influence of estrogens on a number of human cancers (breast, ovarian, colorectal, prostate, and endometrial), endometriosis, fibroids, and cardiovascular disease. A large number of sophisticated experimental studies have provided insights into human disease, but for this review, the literature citations were limited to articles published after our previous review (Deroo and Korach in J Clin Invest 116(3):561–570, 2006) and will focus in most cases on human data and clinical trials. We will describe the influence in which estrogen’s action, through one of or both of the ERs, mediates the aforementioned human disease states. PMID:22648069

  1. Estrogen sulfotransferase ablation sensitizes mice to sepsis

    PubMed Central

    Chai, Xiaojuan; Guo, Yan; Jiang, Mengxi; Hu, Bingfang; Li, Zhigang; Fan, Jie; Deng, Meihong; Billiar, Timothy R.; Kucera, Heidi; Gaikwad, Nilesh W.; Xu, Meishu; Lu, Peipei; Yan, Jiong; Fu, Haiyan; Liu, Youhua; Yu, Lushan; Huang, Min; Zeng, Su; Xie, Wen

    2015-01-01

    Sepsis is the host's deleterious systemic inflammatory response to microbial infections. Here we report an essential role for the estrogen sulfotransferase (EST or SULT1E1), a conjugating enzyme that sulfonates and deactivates estrogens, in sepsis response. Both the cecal ligation and puncture (CLP) and lipopolysacharide (LPS) models of sepsis induce the expression of EST and compromise the activity of estrogen, an anti-inflammatory hormone. Surprisingly, EST ablation sensitizes mice to sepsis-induced death. Mechanistically, EST ablation attenuates sepsis-induced inflammatory responses due to compromised estrogen deactivation, leading to increased sepsis lethality. In contrast, transgenic overexpression of EST promotes estrogen deactivation and sensitizes mice to CLP-induced inflammatory response. The induction of EST by sepsis is NF-κB dependent and EST is a NF-κB target gene. The reciprocal regulation of inflammation and EST may represent a yet to be explored mechanism of endocrine regulation of inflammation, which has an impact on the clinical outcome of sepsis. PMID:26259151

  2. Halogenated catechols from cycloaddition reactions of η-(2-ethoxyvinylketene)iron(0) complexes with 1-haloalkynes.

    PubMed

    Truong, Jimmy; Caze, Vioela; Akhani, Ravish K; Joshi, Gayatribahen K; Kakalis, Lazaros; Matsunaga, Nikita; Schnatter, Wayne F K

    2010-02-10

    1-chloroalkynes and 1-bromohexyne undergo cycloaddition reactions with ethoxyvinylketeneiron(0) complexes to form chloro and bromocatechols. With most substituents, the halogen is incorporated ortho to the phenolic hydroxyl group regioselectively. With chloroethyne, chlorohexyne, and methyl chloropropiolate, the reverse regioselection is observed. Ab initio calculations reveal that the products are, in most cases, nearly isoenergetic, which indicates that the intermediate ketene-alkyne adduct geometry must be important in determining the product distribution.

  3. Synergistic activation of estrogen receptor with combinations of environmental chemicals

    SciTech Connect

    Arnold, S.F.; Klotz, D.M.; Collins, B.M.

    1996-06-07

    Certain chemicals in the environment are estrogenic. The low potencies of the compounds, when studied singly, suggest that they may have little effect on biological systems. The estrogenic potencies of combinations of such chemicals were screened in a simple yeast estrogen potencies of combination of such chemicals were screened in a simple yeast estrogen systems (YES) containing human estrogen receptor (hER). Combinations of two weak environmental estrogens, such as dieldrin, endosulfan, or toxaphene, were 100 times as potent in hER-mediated transactivation as any chemical alone. Hydroxylated polychlorinated biphenyls shown previously to synergistically alter sexual development in turtles also synergized in the YES. The synergistic interaction of chemical mixtures with the estrogen receptor may have profound environmental implications. These results may represent a previously uncharacterized level of regulation of estrogen-associated responses. 32 refs., 3 figs., 3 tabs.

  4. ANALYSIS OF SWINE LAGOONS AND GROUND WATER FOR ENVIRONMENTAL ESTROGENS

    EPA Science Inventory

    A method was developed for analysis of low levels of natural (estradiol, estrone, estriol) and synthetic (ethynylestradiol) estrogens in ground water and swine waste lagoon effluent. The method includes solid phase extraction of the estrogens, preparation of pentafluorobenzyl der...

  5. ANALYSIS OF SWINE LAGOONS AND GROUND WATER FOR ENVIRONMENTAL ESTROGENS

    EPA Science Inventory

    A method was developed for analysis of low levels of natural (estradiol, estrone, estriol) and synthetic (ethinyl estradiol) estrogens in ground water and swine waste lagoon effluent. The method includes solid phase extraction of the estrogens, preparation of pentafluorobenzyl de...

  6. Line narrowing spectroscopic studies of DNA-carcinogen adducts and DNA-dye complexes

    SciTech Connect

    Suh, Myungkoo

    1995-12-06

    Laser-induced fluorescence line narrowing and non-line narrowing spectroscopic methods were applied to conformational studies of stable DNA adducts of the 7{beta}, 8{alpha}-dihydoxy-9{alpha}, l0{alpha}-epoxy-7,8,9, 10-tetrahydrobenzo[{alpha}]pyrene (anti-BPDE). Stereochemically distinct (+)-trans-, ({minus})-trans-, (+)-cis- and ({minus})-cis adducts of anti-BPDE bound to exocyclic amino group of the central guanine in an 11-mer oligonucleotide, exist in a mixture of conformations in frozen aqueous buffer matrices. The (+)-trans adduct adopts primarily an external conformation with a smaller fraction ( {approximately} 25 %) exists in a partially base-stacked conformation. Both cis adducts were found to be intercalated with significant {pi}-{pi} stacking interactions between the pyrenyl residues and the bases. Conformations of the trans-adduct of (+)-anti -BPDE in 11-mer oligonucleotides were studied as a function of flanking bases. In single stranded form the adduct at G{sub 2} or G{sub 3} (5 ft-flanking, base guanine) adopts a conformation with strong, interaction with the bases. In contrast, the adduct with a 5ft-flanking, thymine exists in a primarily helixexternal conformation. Similar differences were observed in the double stranded oligonucleotides. The nature of the 3ft-flanking base has little influence on the conformational equilibrium of the (+)-trans-anti BPDE-dG adduct. The formation and repair of BPDE-N{sup 2}-dG in DNA isolated from the skin of mice treated topically with benzo[{alpha}]pyrene (BP) was studied. Low-temperature fluorescence spectroscopy of the intact DNA identified the major adduct as (+)-trans-anti-BPDE-N-dG, and the minor adduct fraction consisted mainly of (+)-cis-anti-BPDE-N{sup 2}-dG.

  7. Accurate characterization of carcinogenic DNA adducts using MALDI tandem time-of-flight mass spectrometry

    NASA Astrophysics Data System (ADS)

    Barnes, Charles A.; Chiu, Norman H. L.

    2009-01-01

    Many chemical carcinogens and their in vivo activated metabolites react readily with genomic DNA, and form covalently bound carcinogen-DNA adducts. Clinically, carcinogen-DNA adducts have been linked to various cancer diseases. Among the current methods for DNA adduct analysis, mass spectroscopic method allows the direct measurement of unlabeled DNA adducts. The goal of this study is to explore the use of matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF/TOF MS) to determine the identity of carcinogen-DNA adducts. Two of the known carcinogenic DNA adducts, namely N-(2'-deoxyguanosin-8-yl)-2-amino-1-methyl-6-phenyl-imidazo [4,5-b] pyridine (dG-C8-PhIP) and N-(2'-deoxyguanosin-8yl)-4-aminobiphenyl (dG-C8-ABP), were selected as our models. In MALDI-TOF MS measurements, the small matrix ion and its cluster ions did not interfere with the measurements of both selected dG adducts. To achieve a higher accuracy for the characterization of selected dG adducts, 1 keV collision energy in MALDI-TOF/TOF MS/MS was used to measure the adducts. In comparison to other MS/MS techniques with lower collision energies, more extensive precursor ion dissociations were observed. The detection of the corresponding fragment ions allowed the identities of guanine, PhIP or ABP, and the position of adduction to be confirmed. Some of the fragment ions of dG-C8-PhIP have not been reported by other MS/MS techniques.

  8. /sup 32/P-postlabeling analysis of aromatic DNA adducts in fish from polluted areas

    SciTech Connect

    Dunn, B.P.; Black, J.J.; Maccubbin, A.

    1987-12-15

    Brown bullheads (Ictalurus nebulosus) were sampled from sites in the Buffalo and Detroit Rivers where fish are exposed to high levels of sediment bound polycyclic aromatic hydrocarbons, and suffer from an elevated frequency of liver cancer. DNA was isolated from the livers of these wild fish and from control specimens which were raised in clean aquariums. DNA was enzymatically digested to normal and adducted nucleotides, and hydrophobic/bulky adducts were enriched in the digests either by preparative reverse-phase high-pressure liquid chromatography, or selective nuclease P1 dephosphorylation of normal nucleotides. Aromatic DNA-carcinogen adducts were then quantitated using /sup 32/P-postlabeling analysis. Using both adduct enrichment procedures, chromatograms derived from DNA of fish from polluted areas showed a diffuse diagonal radioactive zone not present in DNA from aquarium raised fish. The diagonal zone appeared to consist at least in part of multiple overlapping discrete adduct spots which could be partially separated by gradient high-pressure liquid chromatography prior to /sup 32/P-postlabeling analysis, and most of which were more strongly retained on a reverse-phase column than the major benzo(a)pyrene-DNA adduct. The behavior of the adducts in the diagonal radioactive zone and of their unlabeled precursors is consistent with their identification as nucleotide adducts of a variety of bulky hydrophobic aromatic environmental compounds. Total pollution-related adduct levels as analyzed by HPLC adduct enrichment and /sup 32/P-postlabeling were 70.1 +/- 29 (SD) nmol/mol normal nucleotide in fish from the Buffalo River, and 52 and 56 nmol/mol for two specimens from the Detroit River.

  9. 32P-postlabeling analysis of aromatic DNA adducts in fish from polluted areas.

    PubMed

    Dunn, B P; Black, J J; Maccubbin, A

    1987-12-15

    Brown bullheads (Ictalurus nebulosus) were sampled from sites in the Buffalo and Detroit Rivers where fish are exposed to high levels of sediment bound polycyclic aromatic hydrocarbons, and suffer from an elevated frequency of liver cancer. DNA was isolated from the livers of these wild fish and from control specimens which were raised in clean aquariums. DNA was enzymatically digested to normal and adducted nucleotides, and hydrophobic/bulky adducts were enriched in the digests either by preparative reverse-phase high-pressure liquid chromatography, or selective nuclease P1 dephosphorylation of normal nucleotides. Aromatic DNA-carcinogen adducts were then quantitated using 32P-postlabeling analysis. Using both adduct enrichment procedures, chromatograms derived from DNA of fish from polluted areas showed a diffuse diagonal radioactive zone not present in DNA from aquarium raised fish. The diagonal zone appeared to consist at least in part of multiple overlapping discrete adduct spots which could be partially separated by gradient high-pressure liquid chromatography prior to 32P-postlabeling analysis, and most of which were more strongly retained on a reverse-phase column than the major benzo(a)pyrene-DNA adduct. The behavior of the adducts in the diagonal radioactive zone and of their unlabeled precursors is consistent with their identification as nucleotide adducts of a variety of bulky hydrophobic aromatic environmental compounds. Total pollution-related adduct levels as analyzed by HPLC adduct enrichment and 32P-postlabeling were 70.1 +/- 29 (SD) nmol/mol normal nucleotide in fish from the Buffalo River, and 52 and 56 nmol/mol for two specimens from the Detroit River.

  10. Analysis of serum PAH`s and PAH adducts by LC/MS

    SciTech Connect

    McClure, P.C.; Barr, J.R.; Maggio, V.L.

    1995-12-31

    Polycyclic aromatic hydrocarbons are an important class of chemical carcinogens. Benzo[a]pyrene is the most extensively studied and best understood carcinogenic PAH It is believed that Benzo[a]pyrene is metabolized in vitro to the diol epoxide, Benzo[a]pyrene-7,8-dihydrodiol-9, 10-epoxide which then can react with various nucleophilic centers on DNA. The major alkylation product appears to be the reaction of the Benzo[a]pyrene diol epoxide with the N{sup 2} position of guanine sites on DNA. Methods that can measure exposure and biological response to carcinogens such as PAH`s are needed. Human Blood can be separated into plasma, lymphocytes, and red blood cells. The plasma should contain native PAH`s which may yield some useful information about recent exposure. The red blood cells contain hemoglobin and adducts of PAH`s. Hemoglobin has an average lifetime of 120 days so quantification of hemoglobin adducts should give an average of a persons exposure over four months. Also, the electrophilic metabolites that react with hemoglobin to form adducts are the same metabolites that form DNA adducts which can lead to mutations and cancer. Lymphocytes contain DNA and therefore DNA adducts. DNA adducts can be repaired by a series of enzymes so quantification of these adducts will only yield information about recent or non-repairable adducts. DNA adduct formation is believed to be the first important step in chemical carcinogenesis so quantification of these adducts should yield some information on exposure and a great deal of important data on biological response and risk from specific PAH`s.

  11. [Association of estrogens and selective estrogens receptors modulators: towards a renewal of the hormonal treatment?].

    PubMed

    Valéra, Marie-Cécile; Chantalat, Elodie; Vinel, Alexia; Benoit, Thibaut; Guillaume, Maeva; Game, Xavier; Gourdy, Pierre; Trémollières, Florence; Payrastre, Bernard; Arnal, Jean-François

    2015-01-01

    The life expectancy of women has risen in the past century from 48years to more than 80. The decline of endogenous estrogen production (in particular, the principal circulating physiological hormone, 17β-estradiol) at menopause (which occurs at an average of 51years) is often accompanied by a series of functional disorders that affect quality of life (QoL). This estrogen deficiency affects different tissues and results in an increase in the prevalence of various disorders, including but not limited to osteoporosis and cardiovascular disease. Hormone therapy for menopause is a relatively recent biomedical challenge, which underwent a downturn after the Women Health Initiative study of older postmenopausal women. We will summarize the WHI findings in the first part of this article. At Inserm unit 1048, we are working on understanding the protective effects of estrogen against the development of atherosclerosis and type 2 diabetes in murine models. We have also focused in recent years on modeling the impact of estrogen in thrombosis models, to attempt to clarify the complex relation between estrogen and thrombotic risk. In part II of this article, we will describe a new strategy of hormone therapy for menopause, combining estrogens and selective estrogen receptor modulators (SERM). We review the scientific underpinnings of this strategy, which may enable the renewal of hormone therapy for menopause.

  12. The adverse effects of estrogen and selective estrogen receptor modulators on hemostasis and thrombosis.

    PubMed

    Artero, Arturo; Tarín, Juan J; Cano, Antonio

    2012-11-01

    Agonists of the estrogen receptor include estrogens and selective estrogen receptor modulators (SERMs). Both types of compounds increase the risk for thrombosis in the arterial and the venous tree. The magnitude of the effect is influenced by potency, which depends on the type of compound and the dose. The particulars of the process change in each territory. Atherosclerosis, which creates local inflammatory conditions, may favor thrombogenesis in arteries. A direct effect of estrogen agonists is also well endorsed at both arteries, as suggested from data with high-estrogenic contraceptives, and veins. Dose reduction has been proved to be an effective strategy, but there is debate on whether additional benefit may be attained beyond a certain threshold. Hormone therapy and SERMs exhibit a lower potency estrogenic profile, but are mainly used by older women, who have a baseline increased thrombogenic risk. When used as sole agents, estrogens substantially reduce the increased risk (venous thrombosis) or may even be neutral (coronary disease). SERMs exhibit a neutral profile for coronary disease and possibly for stroke but not for venous thrombosis.

  13. [Low dose estrogens and synthetic estrogens. Options for hormone replacement therapy in climacteric women].

    PubMed

    Velasco-Murillo, Vitelio

    2007-01-01

    A significant increase for cardiovascular disease and breast cancer risks was found in the Women's Health Initiative study in 2002, for current users of conjugated equine estrogens in the habitual dose of 0.625 mg for hormone replacement therapy (HRT) for treating menopausal symptoms. This unexpected finding has caused new-found interest in the world to determine if the use of low-dose estrogens or synthetic estrogens can be useful and safer. At present, there is no scientific evidence about the reduction of such risks with the use of low-dose estrogens. Current medical information has showed that HRT is effective to treat climacteric syndrome and to prevent postmenopausal osteoporosis. In addition, HRT reduces significantly the frequency and severity of vaginal bleeding. Currently the Climacteric and Menopause Program at the Instituto Mexicano del Seguro Social only considers the use of conjugated equine estrogens at the standard dose (0.625 mg). The purpose of this paper is to present some results about use of low-dose estrogens and points of view about synthetic estrogens found in current medical literature. This review aims at contributing to the analysis a possible future use of this type of hormone treatment within the institutional program with the goal of giving safer options to clinicians in managing women with menopausal symptoms.

  14. The formation of covalent adducts between benzo(a)pyrenediol epoxide and RNA: Structural analysis by mass spectrometry

    SciTech Connect

    Yamamoto, J.; Subramaniam, R.; Wolfe, A.R.; Meehan, T. )

    1990-04-24

    Racemic 7-r,8-t-dihydroxy-9-t,10-t-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene was reacted with yeast RNA. Modified nucleosides were isolated and resolved by high-performance liquid chromatography; nine adduct peaks were collected for analysis. The bases in these adducts were identified by comparing their retention time with those of adducts from poly(G), poly(A), and poly(C). These samples gave two major and two minor Guo adducts, four major Ado adducts, and at least four Cyd adducts. The relative efficiencies of adduct formation with the polyribionucleotides were poly(G) > yeast RNA > poly(A) > poly(C). Fluorescence measurements show that emission from Guo adducts is strongly quenched relative to that from Ado adducts. Liquid secondary ion mass spectrometry (LSIMS) of underivatized samples and electron-impact mass spectrometry (EIMS) of permethyl derivatives were used to confirm the base identities and establish the alkylation sites of the RNA adducts. Unique nitrogen-containing hydrocarbon fragments that were observed with all samples by EIMS establish that in each adduct analyzed the C-10 position of the hydrocarbon is linked to the exocyclic amino group of the base. This suggested that the multiple adducts formed with each base are diastereomers derived from cis/trans epoxide ring opening of the (+) and (-) enantiomers of the carcinogen. Major fragmentation pathways resulted in formation of nucleoside, base, ribose, hydrocarbon, and base-hydrocarbon ions.

  15. CYCLOPENTA-FUSED POLYCYCLIC AROMATIC HYDROCARBONS IN STRAIN A/J MOUSE LUNG: DNA ADDUCTS, ONCOGENE MUTATIONS, & TUMORIGENESIS

    EPA Science Inventory

    Cyclopenta-fused Polycyclic Aromatic Hydrocarbons in Strain AJJ Mouse Lung: DNA Adducts, Oncogene Mutations, and Tumorigenesis.

    We have examined the relationships between DNA adducts, Ki-ras oncogene mutations, DNA adducts, and adenoma induction in the lungs of strain A/J...

  16. Multicolor Imaging of Bifacial Activities of Estrogens.

    PubMed

    Kim, Sung-Bae; Umezawa, Yoshio

    2016-01-01

    The present protocol introduces multicolor imaging of bifacial activities of an estrogen. For the multicolor imaging, the authors fabricated two single-chain probes emitting green or red bioluminescence (named Simer-G and -R, respectively) from click beetle luciferase (CBLuc) green and red: Simer-R consists of the ligand binding domain of estrogen receptor (ER LBD) and the Src homology-2 (SH2) domain of Src, which are sandwiched between split-CBLuc red (CBLuc-R). On the other hand, Simer-G emitting red light consists of the ER LBD and a common consensus sequence of coactivators (LXXLL motif), which are inserted between split-CBLuc green (CBLuc-G). This probe set creates fingerprinting spectra from the characteristic green and red bioluminescence in response to agonistic and antagonistic activities of a ligand of interest. The present protocol further provides a unique methodology to calculate characteristic estrogenicity scores of various ligands from the spectra. PMID:27424902

  17. Estrogen receptors in prostate development and cancer

    PubMed Central

    Yeh, Chiuan-Ren; Da, Jun; Song, Wenbin; Fazili, Anees; Yeh, Shuyuan

    2014-01-01

    Prostate cancer (PCa) is an androgen-sensitive disease, which can be pharmacologically controlled by androgen blockade. To date, a growing body of evidence showed that estrogen and estrogen receptors (ERs) could regulate prostate development, as well as cancer initiation and progression. This review will address the expression levels and function of ERs in different stages of PCa progression. The functions of ERs in different types of prostate cells, the ligand effect, and the potential applications of selective estrogen modulators (SERMs) will also be discussed. To further dissect ERs’ roles in prostate development, cell type specific ER knockout mouse models were generated. Results collected from the prostate cell type-specific ERαKO mouse models provided new insights about the cell type specific ERα roles in prostate development prenatally and postnatally. The results of ERs’ roles in mouse PCa mode and the correlation of ERs expression and biomedical outcome will also be discussed. PMID:25374919

  18. Bio-inspired catechol chemistry: a new way to develop a re-moldable and injectable coacervate hydrogel.

    PubMed

    Oh, Yeon Jeong; Cho, Il Hwan; Lee, Haeshin; Park, Ki-Jung; Lee, Hyukjin; Park, Sung Young

    2012-12-18

    A new way is demonstrated to develop a bio-inspired coacervate hydrogel by following catechol chemistry showing injectable and re-moldable physical properties. The formed coacervate shows potential long-term stability under water. Depending on pH, formation of the coacervate has been verified which is confirmed by XPS and zeta potential measurements.

  19. Mesoporous carbon nitride based biosensor for highly sensitive and selective analysis of phenol and catechol in compost bioremediation.

    PubMed

    Zhou, Yaoyu; Tang, Lin; Zeng, Guangming; Chen, Jun; Cai, Ye; Zhang, Yi; Yang, Guide; Liu, Yuanyuan; Zhang, Chen; Tang, Wangwang

    2014-11-15

    Herein, we reported here a promising biosensor by taking advantage of the unique ordered mesoporous carbon nitride material (MCN) to convert the recognition information into a detectable signal with enzyme firstly, which could realize the sensitive, especially, selective detection of catechol and phenol in compost bioremediation samples. The mechanism including the MCN based on electrochemical, biosensor assembly, enzyme immobilization, and enzyme kinetics (elucidating the lower detection limit, different linear range and sensitivity) was discussed in detail. Under optimal conditions, GCE/MCN/Tyr biosensor was evaluated by chronoamperometry measurements and the reduction current of phenol and catechol was proportional to their concentration in the range of 5.00 × 10(-8)-9.50 × 10(-6)M and 5.00 × 10(-8)-1.25 × 10(-5)M with a correlation coefficient of 0.9991 and 0.9881, respectively. The detection limits of catechol and phenol were 10.24 nM and 15.00 nM (S/N=3), respectively. Besides, the data obtained from interference experiments indicated that the biosensor had good specificity. All the results showed that this material is suitable for load enzyme and applied to the biosensor due to the proposed biosensor exhibited improved analytical performances in terms of the detection limit and specificity, provided a powerful tool for rapid, sensitive, especially, selective monitoring of catechol and phenol simultaneously. Moreover, the obtained results may open the way to other MCN-enzyme applications in the environmental field.

  20. VISCOSITY AND BINDER COMPOSITION EFFECTS ON TYROSINASE-BASED CARBON PASTE ELECTRODE FOR DETECTION OF PHENOL AND CATECHOL

    EPA Science Inventory

    The systematic study of the effect of binder viscosity on the sensitivity of a tyrosinase-based carbon paste electrode (CPE) biosensor for phenol and catechol is reported. Silicon oil binders with similar (polydimethylsiloxane) chemical composition were used to represent a wid...

  1. A smartphone-based colorimetric reader coupled with a remote server for rapid on-site catechols analysis.

    PubMed

    Wang, Yun; Li, Yuanyuan; Bao, Xu; Han, Juan; Xia, Jinchen; Tian, Xiaoyu; Ni, Liang

    2016-11-01

    The search of a practical method to analyze cis-diol-containing compounds outside laboratory settings remains a substantial scientific challenge. Herein, a smartphone-based colorimetric reader was coupled with a remote server for rapid on-site analysis of catechols. A smallest-scale 2×2 colorimetric sensor array composed of pH indicators and phenylboronic acid was configured. The array was able to distinguish 13 catechols at 6 serial concentrations, through simultaneous treatment via principal component analysis, hierarchical cluster analysis, and linear discriminant analysis. After both the discriminatory power of the array and the prediction ability of the partial least squares quantitative models were proved to be predominant, the smartphone was coupled to the remote server. All the ΔRGB data were uploaded to the remote server wherein linear discriminant analysis and partial least squares processing modules were established to provide qualitative discrimination and quantitative calculation, respectively, of the analytes in real time. The applicability of this novel method to a real-life scenario was confirmed by the on-site analysis of various catechols from a water sample of the Yangtze River; the feedback result in the smartphone showed the method was able to identify the catechols with 100% accuracy and predict the concentrations to within 0.706-2.240 standard deviation. PMID:27591604

  2. Laccase immobilized on a PAN/adsorbents composite nanofibrous membrane for catechol treatment by a biocatalysis/adsorption process.

    PubMed

    Wang, Qingqing; Cui, Jing; Li, Guohui; Zhang, Jinning; Li, Dawei; Huang, Fenglin; Wei, Qufu

    2014-03-19

    The treatment of catechol via biocatalysis and adsorption with a commercial laccase immobilized on polyacrylonitrile/montmorillonite/graphene oxide (PAN/MMT/GO) composite nanofibers was evaluated with a homemade nanofibrous membrane reactor. The properties in this process of the immobilized laccase on PAN, PAN/MMT as well as PAN/MMT/GO with different weight ratios of MMT and GO were investigated. These membranes were successfully applied for removal of catechol from an aqueous solution. Scanning electron microscope images revealed different morphologies of the enzyme aggregates on different supports. After incorporation of MMT or MMT/GO, the optimum pH showed an alkaline shift to 4, compared to 3.5 for laccase immobilized on pure PAN nanofibers. The optimum temperature was at 55 °C for all the immobilized enzymes. Besides, the addition of GO improved the operational stability and storage stability. A 39% ± 2.23% chemical oxygen demand (COD) removal from the catechol aqueous solution was achieved. Experimental results suggested that laccase, PAN, adsorbent nanoparticles (MMT/GO) can be combined together for catechol treatment in industrial applications.

  3. RATE AND CAPACITY OF HEPATIC MICROSOMAL RING HYDROXYLATION OF PHENOL TO HYDROQUINONE AND CATECHOL IN RAINBOW TROUT (ONCORHYNCHUS MYKISS)

    EPA Science Inventory

    Rainbow trout liver microsomes were used to study the rate of ring-hydroxylation of phenol (PH) by directly measuring the production of hydroquinone (HQ), the primary metabolite, and catechol (CAT), a secondary metabolite. An HPLC method with integrated ultroviolet (UV) and elect...

  4. RATE AND CAPACITY OF HEPATIC MICROSOMAL RING HYDROXYLATION OF PHENOL TO HYDROQUINONE AND CATECHOL IN RAINBOW TROUT

    EPA Science Inventory

    Rainbow trout (Oncorhynchus mykiss) liver microsomes were used to study the rate of ring-hydroxylation of phenol PH) by directly measuring the production of hydroquinone (HQ), the primary metabolite, and catechol (CAT), a secondary metabolite. An HPLC method with integrated ultra...

  5. Susceptibility of Pseudomonas aeruginosa to catechol-substituted cephalosporin is unrelated to the pyochelin-Fe transporter FptA.

    PubMed

    Hoegy, Françoise; Gwynn, Michael N; Schalk, Isabelle J

    2010-05-01

    Previously it has been postulated that the pyochelin-Fe outer membrane transporter, FptA, is involved in the uptake of catechol-substituted cephalosporins in Pseudomonas aeruginosa. Iron uptake and antibacterial activity studies on different mutants showed clearly that FptA is unable to bind and transport these antibiotics. PMID:19777323

  6. Exploration of Dimensions of Estrogen Potency

    PubMed Central

    Jeyakumar, M.; Carlson, Kathryn E.; Gunther, Jillian R.; Katzenellenbogen, John A.

    2011-01-01

    The estrogen receptors, ERα and ERβ, are ligand-regulated transcription factors that control gene expression programs in target tissues. The molecular events underlying estrogen action involve minimally two steps, hormone binding to the ER ligand-binding domain followed by coactivator recruitment to the ER·ligand complex; this ligand·receptor·coactivator triple complex then alters gene expression. Conceptually, the potency of an estrogen in activating a cellular response should reflect the affinities that characterize both steps involved in the assembly of the active ligand·receptor·coactivator complex. Thus, to better understand the molecular basis of estrogen potency, we developed a completely in vitro system (using radiometric and time-resolved FRET assays) to quantify independently three parameters: (a) the affinity of ligand binding to ER, (b) the affinity of coactivator binding to the ER·ligand complex, and (c) the potency of ligand recruitment of coactivator. We used this system to characterize the binding and potency of 12 estrogens with both ERα and ERβ. Some ligands showed good correlations between ligand binding affinity, coactivator binding affinity, and coactivator recruitment potency with both ERs, whereas others showed correlations with only one ER subtype or displayed discordant coactivator recruitment potencies. When ligands with low receptor binding affinity but high coactivator recruitment potencies to ERβ were evaluated in cell-based assays, elevation of cellular coactivator levels significantly and selectively improved their potency. Collectively, our results indicate that some low affinity estrogens may elicit greater cellular responses in those target cells that express higher levels of specific coactivators capable of binding to their ER complexes with high affinity. PMID:21321128

  7. ANALYSIS OF LAGOON SAMPLES FROM DIFFERENT CONCENTRATED ANIMAL FEEDING OPERATIONS (CAFOS) FOR ESTROGENS AND ESTROGEN CONJUGATES (PRESENTATION)

    EPA Science Inventory

    Although Concentrated Animal Feeding Operations (CAFOs) have been identified as potentially important sources for the release of estrogens into the environment, information is lacking on the concentrations of estrogens in whole lagoon effluents (including suspended solids) which ...

  8. Cumulative Estrogen Exposure and Prospective Memory in Older Women

    ERIC Educational Resources Information Center

    Hesson, Jacqueline

    2012-01-01

    This study looked at cumulative lifetime estrogen exposure, as estimated with a mathematical index (Index of Cumulative Estrogen Exposure (ICEE)) that included variables (length of time on estrogen therapy, age at menarche and menopause, postmenopausal body mass index, time since menopause, nulliparity and duration of breastfeeding) known to…

  9. Estrogen Abolishes Latent Inhibition in Ovariectomized Female Rats

    ERIC Educational Resources Information Center

    Nofrey, Barbara S.; Ben-Shahar, Osnat M.; Brake, Wayne G.

    2008-01-01

    Estrogen is frequently prescribed as a method of birth control and as hormone replacement therapy for post-menopausal women with varied effects on cognition. Here the effects of estrogen on attention were examined using the latent inhibition (LI) behavioral paradigm. Ovariectomized (OVX) female rats were given either estrogen benzoate (EB, 10 or…

  10. Vitamin A-aldehyde adducts: AMD risk and targeted therapeutics

    PubMed Central

    Sparrow, Janet R.

    2016-01-01

    Although currently available treatment options for age-related macular degeneration (AMD) are limited, particularly for atrophic AMD, the identification of predisposing genetic variations has informed clinical studies addressing therapeutic options such as complement inhibitors and anti-inflammatory agents. To lower risk of early AMD, recommended lifestyle interventions such as the avoidance of smoking and the intake of low glycemic antioxidant-rich diets have largely followed from the identification of nongenetic modifiable factors. On the other hand, the challenge of understanding the complex relationship between aging and cumulative damage leading to AMD has fueled investigations of the visual cycle adducts that accumulate in retinal pigment epithelial (RPE) cells and are a hallmark of aging retina. These studies have revealed properties of these compounds that provide insights into processes that may compromise RPE and could contribute to disease mechanisms in AMD. This work has also led to the design of targeted therapeutics that are currently under investigation. PMID:27071115

  11. Rotational Spectra of Adducts of Formaldehyde with Freons

    NASA Astrophysics Data System (ADS)

    Qian, Gou; Feng, Gang; Evangelisti, Luca; Caminati, W.; Lopez, Montserrat Vallejo; Lesarri, Alberto; Cocinero, Emilio

    2013-06-01

    The rotational spectra of three 1:1 complexes of formaldehyde (H_{2}CO) with freons, i.e. difluoromethane (CH_{2}F_{2}), fluorochloromethane (CH_{2}FCl) and trifluorochloromethane (CF_{3}Cl), have been observed and assigned using pulsed jet Fourier transform microwave technique. Several isotopologues (including some ^{13}C species) have been measured in natural abundance. The tunnelling splittings have been measured in the first two adducts with relative intensity 1:3, due to the internal rotation of the formaldehyde moity along its symmetry axis. The barriers to this motion have been estimated by using a flexible model. For the latter two complexes, each of transition displays the hyperfine structures due to the quadrupolar effects of ^{35}Cl (^{37}Cl) nucleus. The dissociation energy has been estimated within the pseudo-diatomic approximation for all three complexes.

  12. Coupled redox transformations of catechol and cerium at the surface of a cerium(III) phosphate mineral

    NASA Astrophysics Data System (ADS)

    Cervini-Silva, Javiera; Gilbert, Benjamin; Fakra, Sirine; Friedlich, Stephan; Banfield, Jillian

    2008-05-01

    Highly insoluble Ce-bearing phosphate minerals form by weathering of apatite [Ca5(PO4)3.(OH,F,Cl)], and are important phosphorous repositories in soils. Although these phases can be dissolved via biologically-mediated pathways, the dissolution mechanisms are poorly understood. In this paper we report spectroscopic evidence to support coupling of redox transformations of organic carbon and cerium during the reaction of rhabdophane (CePO4·H2O) and catechol, a ubiquitous biogenic compound, at pH 5. Results show that the oxic-anoxic conditions influence the mineral dissolution behavior. Under anoxic conditions, the release of P and Ce occurs stoichiometrically. In contrast, under oxic conditions, the mineral dissolution behavior is incongruent, with dissolving Ce3+ ions oxidizing to CeO2. Reaction product analysis shows the formation of CO2, polymeric C, and oxalate and malate. The presence of more complex forms of organic carbon was also confirmed. Near edge X-ray absorption fine structure spectroscopy measurements at Ce-M4,5 and C-K absorption edges on reacted CePO4·H2O samples in the absence or presence of catechol and dissolved oxygen confirm that (1) the mineral surface converts to the oxide during this reaction, while full oxidation is limited to the near-surface region only; (2) the Ce valence remains unchanged when the reaction between CePO4·H2O and O2 but in the absence of catechol. Carbon K-edge spectra acquired from rhabdophane reacted with catechol under oxic conditions show spectral features before and after reaction that are considerably different from catechol, indicating the formation of more complex organic molecules. Decreases in intensity of characteristic catechol peaks are accompanied by the appearance of new π∗ resonances due to carbon in carboxyl (ca. 288.5 eV) and carbonyl (ca. 289.3 eV) groups, and the development of broad structure in the σ∗ region characteristic of aliphatic carbon. Evolution of the C K-edge spectra is consistent

  13. Neuronal effects of 4-t-Butylcatechol: A model for catechol-containing antioxidants

    SciTech Connect

    Lo, Y.-C. Liu Yuxin; Lin, Y.-C.; Shih, Y.-T.; Liu, C.-M.; Burka, Leo T.

    2008-04-15

    Many herbal medicines and dietary supplements sold as aids to improve memory or treat neurodegenerative diseases or have other favorable effects on the CNS contain a catechol or similar 1,2-dihydroxy aromatic moiety in their structure. As an approach to isolate and examine the neuroprotective properties of catechols, a simple catechol 4-t-Butylcatechol (TBC) has been used as a model. In this study, we investigated the effects of TBC on lipopolysaccharide (LPS)-activated microglial-induced neurotoxicity by using the in vitro model of coculture murine microglial-like cell line HAPI with the neuronal-like human neuroblastoma cell line SH-SY5Y. We also examined the effects of TBC on 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in human dopaminergic neuroblastoma SH-SY5Y cells. TBC at concentrations from 0.1-10 {mu}M had no toxic effect on HAPI cells and SH-SY5Y cells, and it inhibited LPS (100 ng/ml)-induced increases of superoxide, intracellular ROS, gp91{sup Phox}, iNOS and a decrease of HO-1 in HAPI cells. Under coculture condition, TBC significantly reduced LPS-activated microglia-induced dopaminergic SH-SY5Y cells death. Moreover, TBC (0.1-10 {mu}M) inhibited 6-OHDA-induced increases of intracellular ROS, iNOS, nNOS, and a decrease of mitochondria membrane potential, and cell death in SH-SY5Y cells. However, the neurotoxic effects of TBC (100 {mu}M) on SH-SY5Y cells were also observed including the decrease in mitochondria membrane potential and the increase in COX-2 expression and cell death. TBC-induced SH-SY5Y cell death was attenuated by pretreatment with NS-398, a selective COX-2 inhibitor. In conclusion, this study suggests that TBC might possess protective effects on inflammation- and oxidative stress-related neurodegenerative disorders. However, the high concentration of TBC might be toxic, at least in part, for increasing COX-2 expression.

  14. Non Covalent Interactions and Internal Dynamics in Adducts of Freons

    NASA Astrophysics Data System (ADS)

    Caminati, Walther; Gou, Qian; Evangelisti, Luca; Feng, Gang; Spada, Lorenzo; Vallejo-López, Montserrat; Lesarri, Alberto; Cocinero, Emilio J.

    2014-06-01

    The complexation of chlorofluorocarbons (CFCs) with atmospheric water and pollutants of the atmosphere affects their reactivity and it seems to accelerate, for example, the decomposition rate of freons in the atmosphere [1]. For this reason we characterized shapes, stabilities, nature of the non-covalent interactions, structures and internal dynamics of a number of complexes of CFCs with water and of their dimers or oligomers by rotational spectroscopy. It has been found that hydrogenated CFCs form adducts with other molecules through weak hydrogen bonds (WHBs). Their C-H groups can act as proton donors, enhanced by the electron withdrawing of the halogen atoms, interacting with the electron rich regions of the partner molecules [2]. Also in adducts or oligomers of hydrogenated CFCs the monomer units are held together by nets of WHBs [3]. When CFCs are perhalogenated, the positive electrostatic region ("σ-hole") can interact electrostatically with negative sites of another, or of the same molecular entity, giving rise, according to IUPAC, to the so called halogen bond (HaB). However, it has been observed that when the perhalogenated CFCs has a Π electron system, a lone pair•••Π interaction (Bürgi-Dunitz) is favoured [4]. We describe here the HaBs that CF4 and CF3Cl form with a variety of partner molecules such as water, ammonia, dimethyl ether, etc. Important spectroscopic features outline strong dynamics effects taking place in this kind of complex. References [1] V. Vaida, H. G. Kjaergaard, K. J. Feierabend, Int. Rev. Phys. Chem. 22 (2003) 203. [2] See, for example: W. Caminati, S. Melandri, A. Maris, P. Ottaviani, Angew. Chem. Int. Ed. 45 (2006) 2438. [3] G. Feng, L. Evangelisti, I. Cacelli, L. Carbonaro, G. Prampolini, W. Caminati, Chem. Commun. 50 (2014) 171. [4] Q. Gou, G. Feng, L. Evangelisti, W. Caminati, Angew. Chem. Int. Ed. 52 (2013) 52 11888.

  15. S-adenosylmethionine-dependent protein methylation in mammalian cytosol via tyrphostin modification by catechol-O-methyltransferase.

    PubMed

    Lipson, Rebecca S; Clarke, Steven G

    2007-10-19

    It has previously been shown that incubation of mammalian cell cytosolic extracts with the protein kinase inhibitor tyrphostin A25 results in enhanced transfer of methyl groups from S-adenosyl-[methyl-3H]methionine to proteins. These findings were interpreted as demonstrating tyrphostin stimulation of a novel type of protein carboxyl methyltransferase. We find here, however, that tyrphostin A25 addition to mouse heart cytosol incubated with S-adenosyl-[methyl-3H]methionine or S-adenosyl-[methyl-14C]methionine stimulates the labeling of small molecules in addition to proteins. Base treatment of both protein and small molecule fractions releases volatile radioactivity, suggesting labile ester-like linkages of the labeled methyl group. Production of both the base-volatile product and labeled protein occurs with tyrphostins A25, A47, and A51, but not with thirteen other tyrphostin family members. These active tyrphostins all contain a catechol moiety and are good substrates for recombinant and endogenous catechol-O-methyltransferase. Inhibition of catechol-O-methyltransferase activity with tyrphostin AG1288 prevents both base-volatile product formation and protein labeling from methyl-labeled S-adenosylmethionine in heart, kidney, and liver, but not in testes or brain extracts. These results suggest that the incorporation of methyl groups into protein follows a complex pathway initiated by the methylation of select tyrphostins by endogenous catechol-O-methyltransferase. We suggest that the methylated tyrphostins are further modified in the cell extract and covalently attached to cellular proteins. The presence of endogenous catechols in cells suggests that similar reactions can also occur in vivo.

  16. Estrogen Replacement Therapy for Stroke

    PubMed Central

    Pabon, Mibel; Tamboli, Cyrus; Tamboli, Sarosh; Acosta, Sandra; De La Pena, Ike; Sanberg, Paul R.; Tajiri, Naoki; Kaneko, Yuji; Borlongan, Cesar V.

    2014-01-01

    Stroke is the third most common cause of death and severe disability among Western populations. Overall, the incidence of stroke is uniformly higher in men than in women. Stroke is rare in women during the reproductive years and rapidly increases after menopause, strongly suggesting that estrogen (E2) plays an important role in the prevention of stroke. Ongoing studies are currently evaluating both the benefits and the risks associated with E2 replacement therapy and hormone replacement therapy in stroke. Equally important is the role of E2 receptor (ER), as studies indicate that ER populations in several tissue sites may significantly change during stress and aging. Such changes may affect the patient’s susceptibility to neurological disorders including stroke and greatly affect the response to selective E2 receptor modulators (SERMs). Replacement therapies may be inefficient with low ER levels. The goal of this review paper is to discuss an animal model that will allow investigations of the potential therapeutic effects of E2 and its derivatives in stroke. We hypothesize that E2 neuroprotection is, in part, receptor mediated. This hypothesis is a proof-of-principle approach to demonstrate a role for specific ER subtypes in E2 neuroprotection. To accomplish this, we use a retroviral-mediated gene transfer strategy that expresses subtypes of the ER gene in regions of the rat brain most susceptible to neuronal damage, namely, the striatum and the cortex. The animal model is exposed to experimental stroke conditions involving middle cerebral artery occlusion (MCAo) method, and eventually the extent of neuronal damage will be evaluated. A reduction in neuronal damage is expected when E2 is administered with specific ER subtypes. From this animal model, an optimal E2 dose and treatment regimen can be determined. The animal model can help identify potential E2-like therapeutics in stroke and screen for beneficial or toxic additives present in commercial E2

  17. Detection and characterization of human serum antibodies to polycyclic aromatic hydrocarbon diol-epoxide DNA adducts

    SciTech Connect

    Newman, M.J.; Light, B.A.; Weston, A.; Tollurud, D.; Clark, J.L.; Mann, D.L.; Blackmon, J.P.; Harris, C.C.

    1988-07-01

    The presence of serum antibodies to the diol-epoxide DNA adducts of representative polycyclic aromatic hydrocarbons (PAH), chrysene, benz(a)anthracene and benzo(a)pyrene, was determined by ELISA using serum samples obtained from normal healthy individuals. Antibodies that reacted against PAH adducted-DNA, but not against PAH-adducted protein, were found in the serum of approximately 40% of the test individuals. Specificity analysis of the antibodies demonstrated that serological cross-reactions between the benzo(a)pyrene and the chrysene diol-epoxide adducts were present. Similar cross-reactivity between the benz(a)anthracene and the chrysene adducts was observed. Sera containing antibodies that were apparently specific for each of the three PAH-DNA adducts were also identified. The presence of antibodies to PAH-DNA adducts indicates both past exposure to these carcinogenic PAH and their metabolic activation to the DNA damaging metabolites. These antibodies may prove to be useful in both retrospective and prospective epidemiological studies of various diseases associated with PAH exposure.

  18. Association of end-product adducts with increased IgE binding of roasted peanuts.

    PubMed

    Chung, S Y; Champagne, E T

    2001-08-01

    Recently, we have shown that roasted peanuts have a higher level of IgE binding (i.e., potentially more allergenic) than raw peanuts. We hypothesized that this increase in IgE binding of roasted peanuts is due to an increased levels of protein-bound end products or adducts such as advanced glycation end products (AGE), N-(carboxymethyl)lysine (CML), malondialdehyde (MDA), and 4-hydroxynonenal (HNE). To support our hypothesis, we produced polyclonal antibodies (IgG) to each of these adducts, determined their levels in raw and roasted peanuts, and examined their ability to bind to IgE from a pooled serum of patients with clinically important peanut allergy. Results showed that AGE, CML, MDA, and HNE adducts were all present in raw and roasted peanuts. Roasted peanuts exhibited a higher level of AGE and MDA adducts than raw peanuts. IgE was partially inhibited in a competitive ELISA by antibodies to AGE but not by antibodies to CML, MDA, or HNE. This indicates that IgE has an affinity for peanut AGE adducts. Roasted peanuts exhibited a higher level of IgE binding, which was correlated with a higher level of AGE adducts. We concluded that there is an association between AGE adducts and increased IgE binding (i.e., allergenicity) of roasted peanuts.

  19. Detection and characterization of human serum antibodies to polycyclic aromatic hydrocarbon diol-epoxide DNA adducts.

    PubMed Central

    Newman, M J; Light, B A; Weston, A; Tollurud, D; Clark, J L; Mann, D L; Blackmon, J P; Harris, C C

    1988-01-01

    The presence of serum antibodies to the diol-epoxide DNA adducts of representative polycyclic aromatic hydrocarbons (PAH), chrysene, benz[a]anthracene and benzo[a]pyrene, was determined by ELISA using serum samples obtained from normal healthy individuals. Antibodies that reacted against PAH adducted-DNA, but not against PAH-adducted protein, were found in the serum of approximately 40% of the test individuals. Specificity analysis of the antibodies demonstrated that serological cross-reactions between the benzo[a]pyrene and the chrysene diol-epoxide adducts were present. Similar cross-reactivity between the benz[a]anthracene and the chrysene adducts was observed. Sera containing antibodies that were apparently specific for each of the three PAH-DNA adducts were also identified. The presence of antibodies to PAH-DNA adducts indicates both past exposure to these carcinogenic PAH and their metabolic activation to the DNA damaging metabolites. These antibodies may prove to be useful in both retrospective and prospective epidemiological studies of various diseases associated with PAH exposure. PMID:3392204

  20. Hemoglobin adducts of N-substituted aryl compounds in exposure control and risk assessment.

    PubMed

    Neumann, H G; Birner, G; Kowallik, P; Schütze, D; Zwirner-Baier, I

    1993-03-01

    Arylamines, nitroarenes, and azo dyes yield a common type of metabolite, the nitroarene, which produces a hydrolyzable adduct with protein and is closely related to the critical, ultimate toxic and genotoxic metabolite. The target dose as measured by hemoglobin adducts in erythrocytes reflects not only the actual uptake from the environment but also an individual's capacity for metabolic activation and is therefore an improved dosimeter for human exposure. The usefulness of hemoglobin adducts in molecular epidemiology is now widely recognized. With regard to risk assessment, many questions need to be answered. The described experiments in rats address some of these questions. The relationship between binding to hemoglobin in erythrocytes and to proteins in plasma has been found to vary considerably for a number of diamines. The fraction of hydrolyzable adducts out of the total protein adducts formed also varies in both compartments. This indicates that the kind of circulating metabolites and their availability in different compartments is compound specific. This has to do with the complex pattern of competing metabolic pathways, and the role of N-acetylation and deacetylation is emphasized. An example of nonlinear dose dependence adds to the complexity. Analysis of hemoglobin adducts reveals interesting insights into prevailing pathways, which not only apply to the chemical, but may also be useful to assess an individual's metabolic properties. In addition, it is demonstrated that the greater part of erythrocytes and benzidine-hemoglobin adducts are eliminated randomly in rats, i.e., following first-order kinetics.

  1. Polycyclic aromatic hydrocarbon-DNA adducts and the CYP1A1 restriction fragment length polymorphism

    SciTech Connect

    Shields, P.G.; Bowman, E.D.; Weston, A.; Harris, C.C.; Sugimura, H.; Caporaso, N.E.; Petruzzelli, S.F. ); Trump, B.F. )

    1992-11-01

    Human cancer risk assessment at a genetic level involves the investigation of carcinogen metabolism and DNA adduct formation. Wide interindividual differences in metabolism result in different DNA adduct levels. For this and other reasons, many laboratories have considered DNA adducts to be a measure of the biologically effective dose of a carcinogen. Techniques for studying DNA adducts using chemically specific assays are becoming available. A modification of the [sup 32]P-postlabeling assay for polycyclic aromatic hydrocarbon DNA adducts described here provides potential improvements in quantification. DNA adducts, however, reflect only recent exposure to carcinogens; in contrast, genetic testing for metabolic capacity indicates the extent to which carcinogens can be activated and exert genotoxic effects. Such studies may reflect both separate and integrated risk factors together with DNA adduct levels. A recently described restriction fragment length polymorphism for the CYP1A1, which codes for the cytochrome P450 enzyme primarily responsible for the metabolic activation of carcinogenic polycyclic aromatic hydrocarbons, has been found to be associated with lung cancer risk in a Japanese population. In a subset of individuals enrolled in a US lung cancer case-control study, no association with lung cancer was found. 17 refs., 3 figs.

  2. Bulky DNA adducts in human sperm: relationship with fertility, semen quality, smoking, and environmental factors.

    PubMed

    Horak, Stanislaw; Polanska, Joanna; Widlak, Piotr

    2003-05-01

    The integrity of DNA of spermatogenic cells can be affected by endogenous and exogenous genotoxic factors. Resulting DNA damage in spermatozoa may significantly contribute to impaired fertility. Here, the 32P-postlabeling method was used to analyze the levels of bulky DNA adducts in sperm cells in a group of 179 males, either healthy donors or patients with an impaired fertility. When all donors were analyzed, the levels of bulky DNA adducts was 1.2-fold higher in smokers than in non-smokers, but the difference was not statistically significant (P=0.054). However, a statistically significant difference existed between current smokers and never smokers among the healthy individuals (1.7-fold increase, P=0.008). No correlation between alcohol or coffee consumption and sperm DNA adducts was found. The levels of DNA adducts in sperm seemed to be unaffected by environmental and occupational factors. On the other hand, groups of healthy persons and patients with male-factor infertility differed significantly with respect to the level of bulky DNA adducts (P=0.012). A significant negative correlation between DNA adducts and sperm concentration or sperm motility existed among patients with an impaired fertility (n=93; P<0.029, r(S)=-0.225). These results suggest that DNA adducts in sperm cells can be applied as potential biomarkers in studies of human infertility.

  3. 32P-postlabeling detection of DNA adducts in fish from chemically contaminated waterways.

    PubMed

    Maccubbin, A E; Black, J J; Dunn, B P

    1990-05-01

    Fish were collected from sites in the chemically-contaminated Buffalo River, New York, and the Detroit River, Michigan. The sediments of these rivers have high levels of chemical contaminants, including polycyclic aromatic hydrocarbons (PAHs), and fish from these locations have high prevalences of liver cancer. To determine chemical-DNA interactions and a possible role for chemicals as a cause of the observed tumors, DNA was isolated from livers and was enzymatically digested to normal and adducted nucleotides. The DNA digests were enriched for hydrophobic, bulky adducts, either by preparative reverse phase high pressure liquid chromatography, or by selective nuclease P1 dephosphorylation of normal nucleotides. DNA-chemical adducts were then quantitated by 32P-postlabeling analysis. Regardless of the adduct enrichment procedure, the chromatograms derived from DNA of fish from polluted areas showed a diffuse, diagonal radioactive zone consisting, at least in part, of multiple overlapping discrete adduct spots. The behavior of the adducts in the diagonal radioactive zone and of their unlabeled precursors is consistent with their identification as nucleotide adducts of a variety of bulky, hydrophobic, aromatic genotoxic compounds. Analysis of bile demonstrated recent exposure to multi-ringed aromatic compounds.

  4. 7-Alkylguanine adduct levels in urine, lungs and liver of mice exposed to styrene by inhalation

    SciTech Connect

    Vodicka, Pavel Erik . E-mail: pvodicka@biomed.cas.cz; Linhart, Igor; Novak, Jan; Koskinen, Mikko; Vodickova, Ludmila; Hemminki, Kari

    2006-01-15

    This study describes urinary excretion of two nucleobase adducts derived from styrene 7,8-oxide (SO), i.e., 7-(2-hydroxy-1-phenylethyl)guanine (N7{alpha}G) and 7-(2-hydroxy-2-phenylethyl)guanine (N7{beta}G), as well as a formation of N7-SO-guanine adducts in lungs and liver of two month old male NMRI mice exposed to styrene by inhalation in a 3-week subacute study. Strikingly higher excretion of both isomeric nucleobase adducts in the first day of exposure was recorded, while the daily excretion of nucleobase adducts in following time intervals reached the steady-state level at 4.32 + 1.14 and 6.91 + 1.17 pmol/animal for lower and higher styrene exposure, respectively. {beta}-SO-guanine DNA adducts in lungs increased with exposure in a linear way (F = 13.7 for linearity and 0.17 for non-linearity, respectively), reaching at the 21st day the level of 23.0 adducts/10{sup 8} normal nucleotides, i.e., 0.74 fmol/{mu}g DNA of 7-alkylguanine DNA adducts for the concentration of 1500 mg/m{sup 3}, while no 7-SO-guanine DNA adducts were detected in the liver after 21 days of inhalation exposure to both of styrene concentrations. A comparison of 7-alkylguanines excreted in urine with 7-SO-guanines in lungs (after correction for depurination and for missing {alpha}-isomers) revealed that persisting 7-SO-guanine DNA adducts in lungs account for about 0.5% of the total alkylation at N7 of guanine. The total styrene-specific 7-guanine alkylation accounts for about 1.0 x 10{sup -5}% of the total styrene uptake, while N1-adenine alkylation contributes to this percentage only negligibly.

  5. Antiplatelet Effect of Catechol Is Related to Inhibition of Cyclooxygenase, Reactive Oxygen Species, ERK/p38 Signaling and Thromboxane A2 Production

    PubMed Central

    Wang, Tong-Mei; Lin, Bor-Ru; Yeung, Sin-Yuet; Yeh, Chien-Yang; Cheng, Ru-Hsiu; Jeng, Jiiang-Huei

    2014-01-01

    Catechol (benzenediol) is present in plant-derived products, such as vegetables, fruits, coffee, tea, wine, areca nut and cigarette smoke. Because platelet dysfunction is a risk factor of cardiovascular diseases, including stroke, atherosclerosis and myocardial infarction, the purpose of this study was to evaluate the anti-platelet and anti-inflammatory effect of catechol and its mechanisms. The effects of catechol on cyclooxygenase (COX) activity, arachidonic acid (AA)-induced aggregation, thromboxane B2 (TXB2) production, lactate dehydrogenase (LDH) release, reactive oxygen species (ROS) production and extracellular signal-regulated kinase (ERK)/p38 phosphorylation were determined in rabbit platelets. In addition, its effect on IL-1β-induced prostaglandin E2 (PGE2) production by fibroblasts was determined. The ex vivo effect of catechol on platelet aggregation was also measured. Catechol (5-25 µM) suppressed AA-induced platelet aggregation and inhibited TXB2 production at concentrations of 0.5–5 µM; however, it showed little cytotoxicity and did not alter U46619-induced platelet aggregation. Catechol (10–50 µM) suppressed COX-1 activity by 29–44% and COX-2 activity by 29–50%. It also inhibited IL-1β-induced PGE2 production, but not COX-2 expression of fibroblasts. Moreover, catechol (1–10 µM) attenuated AA-induced ROS production in platelets and phorbol myristate acetate (PMA)-induced ROS production in human polymorphonuclear leukocytes. Exposure of platelets to catechol decreased AA-induced ERK and p38 phosphorylation. Finally, intravenous administration of catechol (2.5–5 µmole/mouse) attenuated ex vivo AA-induced platelet aggregation. These results suggest that catechol exhibited anti-platelet and anti-inflammatory effects, which were mediated by inhibition of COX, ROS and TXA2 production as well as ERK/p38 phosphorylation. The anti-platelet effect of catechol was confirmed by ex vivo analysis. Exposure to catechol may affect platelet

  6. New catechol derivatives of safrole and their antiproliferative activity towards breast cancer cells.

    PubMed

    Madrid Villegas, Alejandro; Espinoza Catalán, Luis; Montenegro Venegas, Iván; Villena García, Joan; Carrasco Altamirano, Héctor

    2011-06-03

    Catechols were synthesized from safrole. Nine derivatives were prepared and assessed for antiproliferative effects using different human cell lines. The in vitro growth inhibition assay was based on the sulphorhodamine dye to quantify cell viability. The derivatives 4-allylbenzene-1,2-diol (3), 4 4-[3-(acetyloxy)propyl]-1,2-phenylene diacetate (6) and 4-[3-(acetyloxy)propyl]-5-nitro-1,2-phenylene diacetate (10) showed higher cytotoxicity than the parent compound 2 in tests performed on two breast cancer cell lines (MCF-7 and MDA-MB-231). The IC₅₀ values of 40.2 ± 6.9 μM, 5.9 ± 0.8 μM and 33.8 ± 4.9 μM, respectively, were obtained without toxicity towards dermal human fibroblast (DHF cells).

  7. Enhanced biological denitrification in the cyclic rotating bed reactor with catechol as carbon source.

    PubMed

    Moussavi, Gholamreza; Jafari, Seyed Javad; Yaghmaeian, Kamyar

    2015-08-01

    The performance of CRBR in denitrification with catechol carbon source is presented. The influence of inlet nitrate concentration, hydraulic retention time (HRT), media filling ratio and rotational speed of media on the performance of CRBR was investigated. The bioreactor could denitrify over 95% of the nitrate at an inlet concentration up to 1000 mg NO3(-)/L and a short HRT as low as 18 h. The optimum media filling ratio at which the maximum denitrification was achieved in the CRBR was 30% and the contribution of media at this condition was around 36%. The optimum ratio of media filling at which the maximum denitrification was 20 rpm and the contribution of rotational speed under this condition was around 17%. According to the findings, the CRBR is a high rate bioreactor and thus serves as an appropriate technology for denitrification of wastewaters containing a high concentration of nitrate and toxic organic compounds. PMID:25898088

  8. Sonolytic hydrolysis of peptides in aqueous solution upon addition of catechol.

    PubMed

    Sakakura, M; Takayama, M

    2009-03-01

    The sonolytic hydrolysis of peptides with addition of phenolic reagents to aqueous solutions is described. Sonolysis of an aqueous solution of peptides to which catechol (o-dihydroxybenzene) had been added resulted in hydrolytic products reflecting the amino acid sequence without any side reactions, while sonolysis without any additives resulted in oxidation analytes and degradation products caused by side reactions. Although the use of additives such as resorcinol (m-dihydroxybenzene), hydroquinone (p-dihydroxybenzene) and phenol was also effective in producing sequence related products, several degradation products were produced by side reactions. A characteristic of the sonolysis of peptides is that the N-terminal side of proline, Xxx-Pro, is more susceptible than other amino acid residues to the process. This characteristic of sonolysis is superior to that of acid hydrolysis in which cleavage at the C-terminal side of proline, Pro-Xxx is difficult, and where dehydration products result due to side reactions.

  9. A two-electron shell game: Intermediates of the extradiol-cleaving catechol dioxygenases

    PubMed Central

    Fielding, Andrew J.

    2014-01-01

    Extradiol catechol ring-cleaving dioxygenases function by binding both the organic substrate and O2 at a divalent metal center in the active site. They have proven to be a particularly versatile group of enzymes with which to study the O2 activation process. Here, recent studies of homoprotocatechuate 2,3-dioxygenase (HPCD) are summarized with the objective of showing how Nature can utilize the enzyme structure and the properties of the metal and the substrate to select among many possible chemical paths to achieve both specificity and efficiency. Possible intermediates in the mechanism have been trapped by swapping active site metals, introducing active site amino acid substituted variants, and using substrates with different electron donating capacities. While each of these intermediates could form part of a viable reaction pathway, kinetic measurements significantly limit the likely candidates. Structural, kinetic, spectroscopic and computational analysis of the various intermediates shed light on how catalytic efficiency can be achieved. PMID:24615282

  10. Seawater-Assisted Self-Healing of Catechol Polymers via Hydrogen Bonding and Coordination Interactions.

    PubMed

    Li, Jincai; Ejima, Hirotaka; Yoshie, Naoko

    2016-07-27

    It is highly desirable to prevent crack formation in polymeric materials at an early stage and to extend their lifespan, particularly when repairs to these materials would be difficult for humans. Here, we designed and synthesized catechol-functionalized polymers that can self-heal in seawater through hydrogen bonding and coordination. These bioinspired acrylate polymers are originally viscous materials, but after coordination with environmentally safe, common metal cations in seawater, namely, Ca(2+) and Mg(2+), the mechanical properties of the polymers were greatly enhanced from viscous to tough, hard materials. Reduced swelling in seawater compared with deionized water owing to the higher osmotic pressure resulted in greater toughness (∼5 MPa) and self-healing efficiencies (∼80%). PMID:27377859

  11. Adsorption/electrosorption of catechol and resorcinol onto high area activated carbon cloth.

    PubMed

    Bayram, Edip; Hoda, Numan; Ayranci, Erol

    2009-09-15

    Removal of catechol and resorcinol from aqueous solutions by adsorption and electrosorption onto high area activated carbon cloth (ACC) was investigated. Kinetics of both adsorption and electrosorption were followed by in-situ UV-spectroscopic method and the data were treated according to pseudo-first-order, pseudo-second-order and intraparticle diffusion models. It was found that the adsorption and electrosorption of these compounds onto ACC follows pseudo-second-order model. pH changes during adsorption and electrosorption were followed and discussed with regard to the interaction between ACC and adsorbate molecules, utilizing the pH(pzc) value of ACC. An electrodesorption experiment was conducted to explore the possibility of regeneration of ACC. Adsorption isotherms were derived at 25 degrees C on the basis of batch analysis. The fits of experimental isotherm data to the well-known Freundlich, Langmuir and Tempkin models were examined. PMID:19345487

  12. Toughening elastomers using mussel-inspired catechol-metal coordination complexes

    NASA Astrophysics Data System (ADS)

    Filippidi, Emmanouela; Christiani, Thomas; Valentine, Megan; Waite, J. Herbert; Israelachvili, Jacob; Ahn, Kollbe

    Amorphous, covalently-linked elastomers possess excellent reversible extensibility and high failure strain compared to other materials. However, by nature, the large deformability compromises the Young's modulus and the toughness of the elastomer to low values (< 2MPa) and imparts brittle fracture. We employ the mussel-inspired strategy of iron-catechol coordination bonding creating dynamic, reversible cross-links in addition to permanent chemical cross-links in an elastomer used in ambient, dry conditions. This simple additional energy dissipative mechanism results in increased modulus and toughness without affecting the network extensibility, which is based on the covalent network. Control of the chain relaxation time scales can be further tuned using the dynamic bonds, imparting mechanical rate dependent properties to the bulk material. The quantitative understanding of the time scales associated with the chain motion versus the metal coordination may provide another simple and independent control parameter in elastomeric material design.

  13. Estrogen, vascular estrogen receptor and hormone therapy in postmenopausal vascular disease.

    PubMed

    Khalil, Raouf A

    2013-12-15

    Cardiovascular disease (CVD) is less common in premenopausal women than men of the same age or postmenopausal women, suggesting vascular benefits of estrogen. Estrogen activates estrogen receptors ERα, ERβ and GPR30 in endothelium and vascular smooth muscle (VSM), which trigger downstream signaling pathways and lead to genomic and non-genomic vascular effects such as vasodilation, decreased VSM contraction and growth and reduced vascular remodeling. However, randomized clinical trials (RCTs), such as the Women's Health Initiative (WHI) and Heart and Estrogen/progestin Replacement Study (HERS), have shown little vascular benefits and even adverse events with menopausal hormone therapy (MHT), likely due to factors related to the MHT used, ER profile, and RCT design. Some MHT forms, dose, combinations or route of administration may have inadequate vascular effects. Age-related changes in ER amount, distribution, integrity and post-ER signaling could alter the vascular response to MHT. The subject's age, preexisting CVD, and hormone environment could also reduce the effects of MHT. Further evaluation of natural and synthetic estrogens, phytoestrogens, and selective estrogen-receptor modulators (SERMs), and the design of appropriate MHT combinations, dose, route and 'timing' could improve the effectiveness of conventional MHT and provide alternative therapies in the peri-menopausal period. Targeting ER using specific ER agonists, localized MHT delivery, and activation of specific post-ER signaling pathways could counter age-related changes in ER. Examination of the hormone environment and conditions associated with hormone imbalance such as polycystic ovary syndrome may reveal the causes of abnormal hormone-receptor interactions. Consideration of these factors in new RCTs such as the Kronos Early Estrogen Prevention Study (KEEPS) could enhance the vascular benefits of estrogen in postmenopausal CVD. PMID:24099797

  14. Estrogen, Vascular Estrogen Receptor and Hormone Therapy in Postmenopausal Vascular Disease

    PubMed Central

    Khalil, Raouf A.

    2013-01-01

    Cardiovascular disease (CVD) is less common in premenopausal women than men of the same age or postmenopausal women, suggesting vascular benefits of estrogen. Estrogen activates estrogen receptors ERα, ERβ and GPR30 in endothelium and vascular smooth muscle (VSM), which trigger downstream signaling pathways and lead to genomic and non-genomic vascular effects such as vasodilation, decreased VSM contraction and growth and reduced vascular remodeling. However, randomized clinical trials (RCTs), such as the Women’s Health Initiative (WHI) and Heart and Estrogen/progestin Replacement Study (HERS), have shown little vascular benefits and even adverse events with menopausal hormone therapy (MHT), likely due to factors related to the MHT used, ER profile, and RCT design. Some MHT forms, dose, combinations or route of administration may have inadequate vascular effects. Age-related changes in ER amount, distribution, integrity and post-ER signaling could alter the vascular response to MHT. The subject’s age, preexisting CVD, and hormone environment could also reduce the effects of MHT. Further evaluation of natural and synthetic estrogens, phytoestrogens, and selective estrogen-receptor modulators (SERMs), and the design of appropriate MHT combinations, dose, route and 'timing' could improve the effectiveness of conventional MHT and provide alternative therapies in the peri-menopausal period. Targeting ER using specific ER agonists, localized MHT delivery, and activation of specific post-ER signaling pathways could counter age-related changes in ER. Examination of the hormone environment and conditions associated with hormone imbalance such as polycystic ovary syndrome may reveal the causes of abnormal hormone-receptor interactions. Consideration of these factors in new RCTs such as the Kronos Early Estrogen Prevention Study (KEEPS) could enhance the vascular benefits of estrogen in postmenopausal CVD. PMID:24099797

  15. Abiotic reduction of nitroaromatic compounds by aqueous iron(ll)-catechol complexes.

    PubMed

    Naka, Daisuke; Kim, Dongwook; Strathmann, Timothy J

    2006-05-01

    Complexation of iron(ll) by catechol and thiol ligands leads to the formation of aqueous species that are capable of reducing substituted nitroaromatic compounds (NACs) to the corresponding anilines. No reactions of NACs are observed in FelI-only or ligand-only solutions. In solutions containing FeII and tiron, a model catechol, rates of NAC reduction are heavily dependent on pH, ligand concentration, and ionic strength. Observed pseudo-first-order rate constants (k(obs)) for 4-chloronitrobenzene reduction vary by more than 6 orders of magnitude, and the variability is well described by the expression k(obs) = k(FeL2)(6-) [FeL2(6-)], where [FeL2(6-)] is the concentration of the 1:2 FeII-tiron complex and kFeL2(6-) is the bimolecular rate constant for 4-chloronitrobenzene reaction with this species. The high reactivity of this FeII species is attributed to the low standard one-electron reduction potential of the corresponding FeIII/FeII redox couple (EH0 = -0.509 V vs NHE). The relative reactivity of different NACs can be described by a linear free-energy relationship (LFER) with the one-electron reduction potentials of the NACs, EH1'(ArNO2). The experimentally derived slope of the LFER indicates that electron transfer is rate determining. These findings suggest that FeII-organic complexes may play an important, previously unrecognized, role in the reductive transformation of persistent organic contaminants.

  16. Formation and Processing of Secondary Organic Aerosol from Catechol as a Model for Atmospheric HULIS

    NASA Astrophysics Data System (ADS)

    Ofner, Johannes; Krüger, Heinz-Ulrich; Grothe, Hinrich; Zetzsch, Cornelius

    2010-05-01

    A particular fraction of the secondary organic aerosol (SOA) termed HUmic Like Substances (HULIS) attracted attention only recently in atmospheric aerosol, initiating a discourse about their aromaticity and other properties, such as reactivity and hygroscopicity. A major portion of HULIS originates from volatile organic compounds, which are formed by abiotic oxidation reactions involving mainly OH radicals, ozone, nitrogen oxides and possibly halogens. Subsequently, the particles provide surface for heterogeneous reactions with atmospheric trace gases. Thus, aerosol smog-chamber studies with appropriate precursors are needed to generate SOA with HULIS qualities in situ inside the smog chamber and study their possible interactions. Catechol and guaiacol were chosen as aromatic precursors for synthetic HULIS production. The SOA was produced in a 700 L aerosol smog chamber, equipped with a solar simulator. SOA formation from each precursor was investigated at simulated environmental conditions (humidity, light, and presence of oxidizers) and characterized with respect to HULIS properties by particle classifiers, Fourier Transform IR spectroscopy (by long-path absorption and attenuated total reflection), UV/VIS spectroscopy, high-resolution mass-spectroscopy and temperature-programmed-desorption mass-spectrometry. High-resolution imaging was obtained using Field Emission Gun Scanning Electron Microscopy (FEGSEM). After HULIS formation the aerosol particles were exposed to atmospheric halogen species to study their processing with those trace gases, released by sea salt-activation. Those investigations show that aromatic precursors like catechol and guaiacol are suitable to form synthetic HULIS for laboratory-scale measurements with physical and chemical properties described in literature. However, sunlight and relative humidity play a major role in particle production and composition of functional groups, which are the anchor points for heterogeneous atmospheric

  17. Conversion of trypsin to a copper enzyme: tyrosinase/catechol oxidase by chemical modification.

    PubMed

    Okutucu, Burcu; Zeytunluoglu, Ali; Zihnioglu, Figen

    2010-01-01

    New active sites can be introduced into naturally occurring enzymes by the chemical modification of specific amino acid residues in concert with genetic techniques. Chemical strategies have had a significant impact in the field of enzyme design such as modifying the selectivity and catalytic activity which is very different from those of the corresponding native enzymes. Thus, chemical modification has been exploited for the incorporation of active site binding analogs onto protein templates and for atom replacement in order to generate new functionality such as the conversion of a hydrolase into a peroxidase. The introduction of a coordination complex into a substrate binding pocket of trypsin could probably also be extended to various enzymes of significant therapeutic and biotechnological importance. The aim of this study is the conversion of trypsin into a copper enzyme: tyrosinase by chemical modification. Tyrosinase is a biocatalyst (EC.1.14.18.1) containing two atoms of copper per active site with monooxygenase activity. The active site of trypsin (EC 3.4.21.4), a serine protease was chemically modified by copper (Cu(+2)) introduced p-aminobenzamidine (pABA- Cu(+2): guanidine containing schiff base metal chelate) which exhibits affinity for the carboxylate group in the active site as trypsin-like inhibitor. Trypsin and the resultant semisynthetic enzyme preparation was analysed by means of its trypsin and catechol oxidase/tyrosinase activity. After chemical modification, trypsin-pABA-Cu(+2) preparation lost 63% of its trypsin activity and gained tyrosinase/catechol oxidase activity. The kinetic properties (K(cat), K(m), K(cat)/K(m)), optimum pH and temperature of the trypsin-pABA-Cu(+2) complex was also investigated. PMID:20024799

  18. Long-term estrogen exposure promotes carcinogen bioactivation, induces persistent changes in gene expression, and enhances the tumorigenicity of MCF-7 human breast cancer cells

    SciTech Connect

    Spink, Barbara C.; Bennett, James A.; Pentecost, Brian T.; Lostritto, Nicole; Englert, Neal A.; Benn, Geoffrey K.; Goodenough, Angela K.; Turesky, Robert J.; Spink, David C.

    2009-11-01

    The cumulative exposure to estrogens is an important determinant in the risk of breast cancer, yet the full range of mechanisms involving estrogens in the genesis and progression of breast cancer remains a subject of debate. Interactions of estrogens and environmental toxicants have received attention as putative factors contributing to carcinogenesis. Mechanistic studies have demonstrated interactions between estrogen receptor alpha (ERalpha) and the aryl hydrocarbon receptor (AhR), with consequences on the genes that they regulate. Many studies of ERalpha and AhR-mediated effects and crosstalk between them have focused on the initial molecular events. In this study, we investigated ERalpha- and AhR-mediated effects in long-term estrogen exposed (LTEE) MCF-7 human breast cancer cells, which were obtained by continuous culturing for at least 12 weeks in medium supplemented with 1 nM of 17beta-estradiol (E{sub 2}). With these LTEE cells and with parallel control cells cultured without E{sub 2} supplementation, we performed an extensive study of cytochrome P450 (CYP) induction, carcinogen bioactivation, global gene expression, and tumorigenicity in immunocompromised mice. We found that LTEE cells, in comparison with control cells, had higher levels of AhR mRNA and protein, greater responsiveness for AhR-regulated CYP1A1 and CYP1B1 induction, a 6-fold higher initial level of benzo(a)pyrene-DNA adducts as determined by liquid chromatography tandem mass spectrometry, marked differences in the expression of numerous genes, and a higher rate of E{sub 2}-dependent tumor growth as xenografts. These studies indicate that LTEE causes adaptive responses in MCF-7 cells, which may reflect processes that contribute to the overall carcinogenic effect of E{sub 2}.

  19. Long-term estrogen exposure promotes carcinogen bioactivation, induces persistent changes in gene expression, and enhances the tumorigenicity of MCF-7 human breast cancer cells

    PubMed Central

    Spink, Barbara C.; Bennett, James A.; Pentecost, Brian T.; Lostritto, Nicole; Englert, Neal A.; Benn, Geoffrey K.; Goodenough, Angela K.; Turesky, Robert J.; Spink, David C.

    2009-01-01

    The cumulative exposure to estrogens is an important determinant in the risk of breast cancer, yet the full range of mechanisms involving estrogens in the genesis and progression of breast cancer remains a subject of debate. Interactions of estrogens and environmental toxicants have received attention as putative factors contributing to carcinogenesis. Mechanistic studies have demonstrated interactions between estrogen receptor α (ERα) and the aryl hydrocarbon receptor (AhR), with consequences on the genes that they regulate. Many studies of ERα and AhR-mediated effects and crosstalk between them have focused on the initial molecular events. In this study, we investigated ERα- and AhR-mediated effects in long-term estrogen exposed (LTEE) MCF-7 human breast cancer cells, which were obtained by continuous culturing for at least 12 weeks in medium supplemented with 1 nM of 17β-estradiol (E2). With these LTEE cells and with parallel control cells cultured without E2 supplementation, we performed an extensive study of cytochrome P450 (CYP) induction, carcinogen bioactivation, global gene expression, and tumorigenicity in immunocompromised mice. We found that LTEE cells, in comparison with control cells, had higher levels of AhR mRNA and protein, greater responsiveness for AhR-regulated CYP1A1 and CYP1B1 induction, a 6-fold higher initial level of benzo(a)pyrene-DNA adducts as determined by liquid chromatography tandem mass spectrometry, marked differences in the expression of numerous genes, and a higher rate of E2-dependent tumor growth as xenografts. These studies indicate that LTEE causes adaptive responses in MCF-7 cells, which may reflect processes that contribute to the overall carcinogenic effect of E2. PMID:19619570

  20. Base-Displaced Intercalated Structure of the N-(2'-Deoxyguanosin-8-yl)-3-aminobenzanthrone DNA Adduct.

    PubMed

    Politica, Dustin A; Malik, Chanchal K; Basu, Ashis K; Stone, Michael P

    2015-12-21

    3-Nitrobenzanthrone (3-NBA), an environmental mutagen found in diesel exhaust and a suspected carcinogen, undergoes metabolic reduction followed by reaction with DNA to form aminobenzanthrone (ABA) adducts, with the major alkylation product being N-(2'-deoxyguanosin-8-yl)-3-aminobenzanthrone (C8-dG-ABA). Site-specific synthesis of the C8-dG-ABA adduct in the oligodeoxynucleotide 5'-d(GTGCXTGTTTGT)-3':5'-d(ACAAACACGCAC)-3'; X = C8-dG-ABA adduct, including codons 272-275 of the p53 gene, has allowed for investigation into the structural and thermodynamic properties of this adduct. The conformation of the C8-dG-ABA adduct was determined using NMR spectroscopy and was refined using molecular dynamics (MD) calculations restrained by experimentally determined interproton distance restraints obtained from NOE experiments. The refined structure revealed that the C8-dG-ABA adduct formed a base-displaced intercalated conformation. The adducted guanine was shifted into the syn conformation about the glycosidic bond. The 5'- and 3'-neighboring base pairs remained intact. While this facilitated π-stacking interactions between the ABA moiety and neighboring bases, the thermal melting temperature (Tm) of the adduct-containing duplex showed a decrease of 11 °C as compared to the corresponding unmodified oligodeoxynucleotide duplex. Overall, in this sequence, the base-displaced intercalated conformation of the C8-dG-ABA lesion bears similarity to structures of other arylamine C8-dG adducts. However, in this sequence, the base-displaced intercalated conformation for the C8-dG-ABA adduct differs from the conformation of the N(2)-dG-ABA adduct reported by de los Santos and co-workers, in which it is oriented in the minor groove toward the 5' end of the duplex, with the modified guanine remaining in the anti conformation about the glyosidic torsion angle, and the complementary base remaining within the duplex. The results are discussed in relationship to differences between the C8-d

  1. Preferential Formation of Benzo[a]pyrene Adducts at Lung Cancer Mutational Hotspots in P53

    NASA Astrophysics Data System (ADS)

    Denissenko, Mikhail F.; Pao, Annie; Tang, Moon-Shong; Pfeifer, Gerd P.

    1996-10-01

    Cigarette smoke carcinogens such as benzo[a]pyrene are implicated in the development of lung cancer. The distribution of benzo[a]pyrene diol epoxide (BPDE) adducts along exons of the P53 gene in BPDE-treated HeLa cells and bronchial epithelial cells was mapped at nucleotide resolution. Strong and selective adduct formation occurred at guanine positions in codons 157, 248, and 273. These same positions are the major mutational hotspots in human lung cancers. Thus, targeted adduct formation rather than phenotypic selection appears to shape the P53 mutational spectrum in lung cancer. These results provide a direct etiological link between a defined chemical carcinogen and human cancer.

  2. DNA adducts in human pancreatic tissues and their potential role in carcinogenesis.

    PubMed

    Wang, M; Abbruzzese, J L; Friess, H; Hittelman, W N; Evans, D B; Abbruzzese, M C; Chiao, P; Li, D

    1998-01-01

    Pancreas cancer is the fourth and fifth leading cause of cancer death for men and women, respectively, in the United States. Although the etiology of this cancer is poorly understood, smoking and dietary fat have been implicated by epidemiological studies. To test the hypothesis that DNA damage derived from carcinogen exposure and diet is involved in pancreatic carcinogenesis, aromatic and lipid peroxidation-related DNA adducts in 13 normal tissues adjacent to tumor and 20 tumors from pancreatic cancer patients were analyzed by 32P-postlabeling. Normal pancreatic tissues from 5 nonpancreatic cancer patients and 19 healthy organ donors served as controls. To correlate the DNA adduct level with patients' characteristics, information on age, sex, body mass index, and smoking status of pancreatic cancer patients were collected from medical records. A significantly higher level of total DNA adducts was detected in pancreatic cancer patients as compared with controls. The mean level of adducts/10(8) nucleotides in adjacent normal pancreatic tissues from pancreatic cancer patients (A tissues) was 102 +/- 21 compared with 39 +/- 6 and 13 +/- 1 in pancreatic tumor tissues (T tissues) and normal pancreatic tissues from controls (C tissues), respectively. Among the adducts observed, one single aromatic adduct (spot 1) was present in 100, 90, and 0% of the A, T, and C tissues, respectively. Two novel clusters of adducts (spots 2 and 3) were observed in 11 of 13, 12 of 20, and 2 of 24 of A, T, and C tissues, respectively, and the presence of these adducts was positively correlated with smoking status. In addition, the previously defined smoking-related diagonal radioactive zone was detected in three A samples only, although 50% (10 of 20) of the patients with pancreatic cancers in this study were ever smokers. Putative lipid peroxidation-related adducts were detected in all samples examined and were significantly higher in A than in T and C samples. Multiple regression analyses

  3. Base-Displaced Intercalated Structure of the N-(2'-Deoxyguanosin-8-yl)-3-aminobenzanthrone DNA Adduct.

    PubMed

    Politica, Dustin A; Malik, Chanchal K; Basu, Ashis K; Stone, Michael P

    2015-12-21

    3-Nitrobenzanthrone (3-NBA), an environmental mutagen found in diesel exhaust and a suspected carcinogen, undergoes metabolic reduction followed by reaction with DNA to form aminobenzanthrone (ABA) adducts, with the major alkylation product being N-(2'-deoxyguanosin-8-yl)-3-aminobenzanthrone (C8-dG-ABA). Site-specific synthesis of the C8-dG-ABA adduct in the oligodeoxynucleotide 5'-d(GTGCXTGTTTGT)-3':5'-d(ACAAACACGCAC)-3'; X = C8-dG-ABA adduct, including codons 272-275 of the p53 gene, has allowed for investigation into the structural and thermodynamic properties of this adduct. The conformation of the C8-dG-ABA adduct was determined using NMR spectroscopy and was refined using molecular dynamics (MD) calculations restrained by experimentally determined interproton distance restraints obtained from NOE experiments. The refined structure revealed that the C8-dG-ABA adduct formed a base-displaced intercalated conformation. The adducted guanine was shifted into the syn conformation about the glycosidic bond. The 5'- and 3'-neighboring base pairs remained intact. While this facilitated π-stacking interactions between the ABA moiety and neighboring bases, the thermal melting temperature (Tm) of the adduct-containing duplex showed a decrease of 11 °C as compared to the corresponding unmodified oligodeoxynucleotide duplex. Overall, in this sequence, the base-displaced intercalated conformation of the C8-dG-ABA lesion bears similarity to structures of other arylamine C8-dG adducts. However, in this sequence, the base-displaced intercalated conformation for the C8-dG-ABA adduct differs from the conformation of the N(2)-dG-ABA adduct reported by de los Santos and co-workers, in which it is oriented in the minor groove toward the 5' end of the duplex, with the modified guanine remaining in the anti conformation about the glyosidic torsion angle, and the complementary base remaining within the duplex. The results are discussed in relationship to differences between the C8-d

  4. DNA Adduct Formation of 4-Aminobiphenyl and Heterocyclic Aromatic Amines in Human Hepatocytes

    PubMed Central

    Nauwelaers, Gwendoline; Bessette, Erin E.; Gu, Dan; Tang, Yijin; Rageul, Julie; Fessard, Valérie; Yuan, Jian-Min; Yu, Mimi C.; Langouët, Sophie; Turesky, Robert J.

    2011-01-01

    DNA adduct formation of the aromatic amine, 4-aminobiphenyl (4-ABP), a known human carcinogen present in tobacco smoke, and the heterocyclic aromatic amines (HAAs), 2-amino-9H-pyrido[2,3-b]indole (AαC), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), and 2-amino-3,8-dimethylmidazo[4,5-f]quinoxaline (MeIQx), potential human carcinogens, which are also present in tobacco smoke or formed during the high-temperature cooking of meats, was investigated in freshly cultured human hepatocytes. The carcinogens (10 μM) were incubated with hepatocytes derived from eight different donors for time periods up to 24 h. The DNA adducts were quantified by liquid chromatography-electrospray ionization mass spectrometry with a linear quadrupole ion trap mass spectrometer. The principal DNA adducts formed for all of the carcinogens were N-(deoxyguanosin-8-yl) (dG-C8) adducts. The levels of adducts ranged from 3.4 to 140 adducts per 107 DNA bases. The highest level of adduct formation occurred with AαC, followed by 4-ABP, then by PhIP, MeIQx, and IQ. Human hepatocytes formed dG-C8-HAA-adducts at levels that were up to 100-fold greater than the amounts of adducts produced in rat hepatocytes. In contrast to HAA adducts, the levels of dG-C8-4-ABP adduct formation were similar in human and rat hepatocytes. These DNA binding data demonstrate that the rat, an animal model that is used for carcinogenesis bioassays, significantly underestimates the potential hepatic genotoxicity of HAAs in humans. The high level of DNA adducts formed by AαC, a carcinogen produced in tobacco smoke at levels that are up to 100-fold higher than the amounts of 4-ABP, is noteworthy. The possible causal role of AαC in tobacco-associated cancers warrants investigation. PMID:21456541

  5. Gynecomastia caused by estrogen containing hair lotion.

    PubMed

    Gottswinter, J M; Korth-Schütz, S; Ziegler, R

    1984-08-01

    Two men at the age of 48 and 54 yr developed gynecomastia and lost their potency after the use of estrogen containing hair lotions. During exposure to the lotion the levels of 17-beta estradiol were increased, whereas the levels of testosterone and gonadotropins were depressed. Thus, a previous application of such hair lotions should be considered in the differential diagnosis of gynecomastia.

  6. Histopathologic Effects of Estrogens on Marine Fishes

    EPA Science Inventory

    Endocrine-disrupting chemicals (EDCs), such as estrogens estradiol (E2) and ethinylestradiol (EE2) have been reported to affect fish reproduction. This study histologically compared and evaluated effects of EDCs in two species of treated fish. Juvenile male summer flounder (Paral...

  7. Estrogen receptor expert system overview and examples

    EPA Science Inventory

    The estrogen receptor expert system (ERES) is a rule-based system developed to prioritize chemicals based upon their potential for binding to the ER. The ERES was initially developed to predict ER affinity of chemicals from two specific EPA chemical inventories, antimicrobial pe...

  8. [Pharmacodynamics of synthetic estrogens. Review article].

    PubMed

    Sojo-Aranda, I; Cortés-Gallegos, V

    1990-10-01

    Some details about the function of natural and synthetical hormonas are reviewed, particularly estrogens as ethynyl estradiol and its 3, Methyl ether (mestranol); its peripheral concentration vs tissular hormonal contents, a relationship of biological importance as the first step in its hormonal action and the cummulative local effects that could explain some intra and extracellular phenomena.

  9. [Pharmacodynamics of synthetic estrogens. A review].

    PubMed

    Sojo-Aranda, I; Cortés-Gallegos, V

    1990-10-01

    Some details about the function of natural and synthetical hormonas are reviewed, particularly estrogens as ethynyl estradiol and its 3, Methyl ether (mestranol); its peripheral concentration vs tissular hormonal contents, a relationship of biological importance as the first step in its hormonal action and the cumulative local effects that could explain some intra and extracellular phenomena.

  10. [Pharmacodynamics of synthetic estrogens. Review article].

    PubMed

    Sojo-Aranda, I; Cortés-Gallegos, V

    1990-10-01

    Some details about the function of natural and synthetical hormonas are reviewed, particularly estrogens as ethynyl estradiol and its 3, Methyl ether (mestranol); its peripheral concentration vs tissular hormonal contents, a relationship of biological importance as the first step in its hormonal action and the cummulative local effects that could explain some intra and extracellular phenomena. PMID:2292429

  11. Women's Skills Linked to Estrogen Levels.

    ERIC Educational Resources Information Center

    Weiss, R.

    1988-01-01

    Summarizes the result of research which considers the effect of women's hormone level on specific skills. Reports that low estrogen levels allow women to excel at spatial skills, but perform poorly at complex motor tasks and speech articulation. Discusses some implications and further research ideas. (YP)

  12. HUMAN HEALTH IMPACT OF ENVIRONMENTAL ESTROGENIC CHEMICALS

    EPA Science Inventory

    HUMAN HEALTH IMPACT OF ENVIRONMENTAL ESTROGENIC CHEMICALS.

    Robert J. Kavlock, Reproductive Toxicology Division, NHEERL, ORD, US Environmental Protection Agency, Research Triangle Park, NC USA.

    Over the past several decades a hypothesis has been put forth that a numb...

  13. [Equine estrogens vs. esterified estrogens in the climacteric and menopause. The controversy arrives in Mexico].

    PubMed

    Velasco-Murillo, V

    2001-01-01

    It exists controversies about if the effects and benefits of the esterified estrogens could be similar to those informed for equines, because its chemical composition and bioavailability are different. Esterified estrogens has not delta 8,9 dehydroestrone, and its absorption and level of maximum plasmatic concentrations are reached very fast. In United States of America and another countries, esterified estrogens has been marketed and using for treatment of climacteric syndrome and prevention of postmenopausal osteoporosis, based on the pharmacopoiea of that country, but the Food and Drug administration (FDA) has not yet authorized up today, a generic version of conjugated estrogens. In Instituto Mexicano del Seguro Social (IMSS) and another institutions of health sector in Mexico, starting in year 2000, it has been used esterified estrogens for medical treatment of climacteric and menopausal conditions. For this reason, in this paper we revised the most recent information about pharmacology, chemical composition, clinical use and costs of the conjugated estrogens with the purpose to guide the decisions to purchase this kind of drugs in Mexican heath institutions.

  14. Adenine-DNA adducts derived from the highly tumorigenic dibenzo[a,l]pyrene are resistant to nucleotide excision repair while guanine adducts are not

    PubMed Central

    Kropachev, Konstantin; Kolbanovskiy, Marina; Liu, Zhi; Cai, Yuqin; Zhang, Lu; Schwaid, Adam G.; Kolbanovskiy, Alexander; Ding, Shuang; Amin, Shantu; Broyde, Suse; Geacintov, Nicholas E.

    2013-01-01

    The structural origins of differences in susceptibilities of various DNA lesions to nucleotide excision repair (NER) are poorly understood. Here we compared, in the same sequence context, the relative NER dual incision efficiencies elicited by two stereochemically distinct pairs of guanine (N2-dG) and adenine (N6-dA) DNA lesions, derived from enantiomeric genotoxic diol epoxides of the highly tumorigenic fjord region polycyclic aromatic hydrocarbon dibenzo[a,l]pyrene (DB[a,l]P). Remarkably, in cell-free HeLa cell extracts, the guanine adduct with R absolute chemistry at the N2-dG linkage site is ~ 35 times more susceptible to NER dual incisions than the stereochemically identical N6-dA adduct. For the guanine and adenine adducts with S stereochemistry, a similar, but somewhat smaller effect (factor of ~15) is observed. The striking resistance of the bulky N6-dA in contrast to the modest to good susceptibilities of the N2-dG adducts to NER are interpreted in terms of the balance between lesion-induced DNA-distorting and DNA-stabilizing van der Waals interactions in their structures, that are partly reflected in the overall thermal stabilities of the modified duplexes. Our results are consistent with the hypothesis that the high genotoxic activity of DB[a,l]P is related to the formation of NER-resistant and persistent DB[a,l]P-derived adenine adducts in cellular DNA. PMID:23570232

  15. Identification of an estrogenic hormone receptor in Caenorhabditis elegans

    SciTech Connect

    Mimoto, Ai; Fujii, Madoka; Usami, Makoto; Shimamura, Maki; Hirabayashi, Naoko; Kaneko, Takako; Sasagawa, Noboru; Ishiura, Shoichi

    2007-12-28

    Changes in both behavior and gene expression occur in Caenorhabditis elegans following exposure to sex hormones such as estrogen and progesterone, and to bisphenol A (BPA), an estrogenic endocrine-disrupting compound. However, only one steroid hormone receptor has been identified. Of the 284 known nuclear hormone receptors (NHRs) in C. elegans, we selected nhr-14, nhr-69, and nhr-121 for analysis as potential estrogenic hormone receptors, because they share sequence similarity with the human estrogen receptor. First, the genes were cloned and expressed in Escherichia coli, and then the affinity of each protein for estrogen was determined using a surface plasmon resonance (SPR) biosensor. All three NHRs bound estrogen in a dose-dependent fashion. To evaluate the specificity of the binding, we performed a solution competition assay using an SPR biosensor. According to our results, only NHR-14 was able to interact with estrogen. Therefore, we next examined whether nhr-14 regulates estrogen signaling in vivo. To investigate whether these interactions actually control the response of C. elegans to hormones, we investigated the expression of vitellogenin, an estrogen responsive gene, in an nhr-14 mutant. Semi-quantitative RT-PCR showed that vitellogenin expression was significantly reduced in the mutant. This suggests that NHR-14 is a C. elegans estrogenic hormone receptor and that it controls gene expression in response to estrogen.

  16. Differential effects of Glycyrrhiza species on genotoxic estrogen metabolism: licochalcone A downregulates P450 1B1 whereas isoliquiritigenin stimulates

    PubMed Central

    Dunlap, Tareisha L.; Wang, Shuai; Simmler, Charlotte; Chen, Shao-Nong; Pauli, Guido F.; Dietz, Birgit M.; Bolton, Judy L.

    2015-01-01

    Estrogen chemical carcinogenesis involves 4-hydroxylation of estrone/estradiol (E1/E2) by P450 1B1, generating catechol and quinone genotoxic metabolites that cause DNA mutations and initiate/promote breast cancer. Inflammation enhances this effect by up-regulating P450 1B1. The present study tested the three authenticated medicinal species of licorice, [Glycyrrhiza glabra (GG), G. uralensis (GU), and G. inflata (GI)], used by women as dietary supplements, for their anti-inflammatory activities and their ability to modulate estrogen metabolism. The pure compounds, liquiritigenin (LigF), its chalcone isomer isoliquiritigenin (LigC), and the GI specific licochalcone A (LicA) were also tested. The licorice extracts and compounds were evaluated for anti-inflammatory activity by measuring inhibition of iNOS activity in macrophage cells: GI > GG > GU and LigC ≅ LicA > LigF. The Michael acceptor chalcone LicA, is likely responsible for the anti-inflammatory activity of GI. A sensitive LC-MS/MS assay was employed to quantify estrogen metabolism by measuring 2-MeOE1 as non-toxic and 4-MeOE1 as genotoxic biomarkers in the non-tumorigenic human mammary epithelial cell line, MCF-10A. GG, GU, and LigC increased 4-MeOE1, whereas GI and LicA inhibited 2- and 4-MeOE1 levels. GG, GU (5 μg/mL), and LigC (1 μM) also enhanced P450 1B1 expression and activities, which was further increased by inflammatory cytokines (TNF-α and IFN-γ). LicA (1 μM, 10 μM) decreased cytokine- and TCDD-induced, P450 1B1 gene expression and TCDD-induced xenobiotic response element luciferase reporter (IC50=12.3 μM), suggesting an antagonistic effect on the aryl hydrocarbon receptor, which regulates P450 1B1. Similarly, GI (5 μg/mL) reduced cytokine- and TCDD-induced P450 1B1 gene expression. Collectively, these data suggest that of the three licorice species that are used in botanical supplements, GI represents the most promising chemopreventive licorice extract for women’s health. Additionally

  17. Analysis of estrogenic activity in environmental waters in Rio de Janeiro state (Brazil) using the yeast estrogen screen.

    PubMed

    Dias, Amanda Cristina Vieira; Gomes, Frederico Wegenast; Bila, Daniele Maia; Sant'Anna, Geraldo Lippel; Dezotti, Marcia

    2015-10-01

    The estrogenicity of waters collected from an important hydrological system in Brazil (Paraiba do Sul and Guandu Rivers) was assessed using the yeast estrogen screen (YES) assay. Sampling was performed in rivers and at the outlets of conventional water treatment plants (WTP). The removal of estrogenic activity by ozonation and chlorination after conventional water treatment (clarification and sand filtration) was investigated employing samples of the Guandu River spiked with estrogens and bisphenol A (BPA). The results revealed a preoccupying incidence of estrogenic activity at levels higher than 1ngL(-1) along some points of the rivers. Another matter of concern was the number of samples from WTPs presenting estrogenicity surpassing 1ngL(-1). The oxidation techniques (ozonation and chlorination) were effective for the removal of estrogenic activity and the combination of both techniques led to good results using less amounts of oxidants. PMID:26024813

  18. Effects of Endogenous Ovarian Estrogen Versus Exogenous Estrogen Replacement on Blood Flow and ERα and ERβ Levels in the Bladder

    PubMed Central

    Ablove, Tova S.; Austin, Jason L.; Phernetton, Terry M.; Magness, Ronald R.

    2011-01-01

    Objective Determine the effect of endogenous estrogen versus estrogen replacement therapy (ERT) on bladder blood flow (BBF) and estrogen receptors (ERs). Methods BBF was determined with radio-labeled microspheres in luteal, follicular, pregnant, oophorectomized (Ovx) sheep, and Ovx sheep with ERT. Estrogen receptors (ERα, ERβ) were quantified using Western blot analysis. Results Compared to luteal and follicular ewes, BBF was reduced in pregnancy and following oophorectomy. Estrogen replacement therapy in Ovx sheep restored BBF to luteal levels. Estrogen receptor α predominated, whereas ERβ was not detectable. Estrogen receptor-α levels were unaffected by the ovarian cycle and increased in pregnancy, as well as in Ovx sheep with and without chronic ERT. Conclusion The combination of diminished BBF and elevated ERα levels in both pregnant and Ovx sheep suggests an inverse relationship between BBF and ERα in the bladder. Although chronic ERT in Ovx sheep restored BBF, it did not restore ERα back to luteal levels. PMID:19535742

  19. Surface modification of anatase nanoparticles with fused ring catecholate type ligands: a combined DFT and experimental study of optical properties

    NASA Astrophysics Data System (ADS)

    Savić, Tatjana D.; Janković, Ivana A.; Šaponjić, Zoran V.; Čomor, Mirjana I.; Veljković, Dušan Ž.; Zarić, Snežana D.; Nedeljković, Jovan M.

    2012-02-01

    Surface modification of nanocrystalline TiO2 particles (45 Å) with catecholate-type ligands consisting of an extended aromatic ring system, i.e., 2,3-dihydroxynaphthalene and anthrarobin, was found to alter the optical properties of the nanoparticles in a similar way to modification with catechol. The formation of inner-sphere charge-transfer (CT) complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites and the reduction of the band gap upon the increase of the electron delocalization on the inclusion of additional rings. The binding structures were investigated by FTIR spectroscopy. The investigated ligands have the optimal geometry for binding to surface Ti atoms, resulting in ring coordination complexes of catecholate type (binuclear bidentate binding-bridging) thus restoring the six-coordinated octahedral geometry of surface Ti atoms. From the Benesi-Hildebrand plot, stability constants in methanol/water = 90/10 solutions at pH 2 of the order 103 M-1 have been determined. Quantum chemical calculations on model systems using density functional theory (DFT) were performed to obtain vibrational frequencies of charge transfer complexes, and the calculated values were compared with the experimental data.Surface modification of nanocrystalline TiO2 particles (45 Å) with catecholate-type ligands consisting of an extended aromatic ring system, i.e., 2,3-dihydroxynaphthalene and anthrarobin, was found to alter the optical properties of the nanoparticles in a similar way to modification with catechol. The formation of inner-sphere charge-transfer (CT) complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites and the reduction of the band gap upon the increase of the electron delocalization on the inclusion of additional rings. The binding structures were investigated by FTIR spectroscopy. The investigated ligands have the optimal geometry for binding to surface Ti atoms

  20. Second vowel formant relationship to adduction: A preliminary study

    NASA Astrophysics Data System (ADS)

    Hanrahan, Kevin G.

    The relationship between the vocal tract and the larynx in the formation of vowels has been debated for decades. Vowels were first thought to have been formed in the larynx; then later it was believed that they were formed solely in the vocal tract. In the 1960s Fant formalized this belief into the Source-Filter Theory of Vowel Formation. The theory was interpreted by voice teachers to mean that the larynx had very little to do with the formation of vowels, and this interpretation has dominated voice teaching for decades. Recent research, however, is now suggesting that the larynx and the vocal tract are interactive with each other, meaning that a change of muscular function in the larynx will create a change of resonator function in the vocal tract, and vice versa. This conclusion is drawn mainly on the work of Titze, Story, Laukkanen, et.al. They have found that a relationship exists between laryngeal function and the first vowel formant (F1). When examining research on the second vowel formant (F2), this author discovered that there may be a relationship between F2 and adduction. Therefore, based on present evidence, it was hypothesized that an elevated frequency of F2 corresponded to an increase in adduction. The hypothesis was examined by comparing the resonance output and glottal closure between vowels where F2 was elevated and vowels without modification of F2. Subjects were asked to sing [i], [a], and [u] at a medium dynamic level on D4, G#4, and D5 for the female subjects and an octave below for the male subjects, once using a "generic" version of the vowel, meaning what they considered a "nice, easy, and generic" version of the vowel to be, and then again modifying the vowel to increase the frequency of the upper harmonics. Electroglottogram, pitch, intensity, and formant data were collected and compared. An increase in the frequency of F2 corresponded to an increase in the Closed Quotient (CQ), the length of time the vocal folds are closed, in a few

  1. Auto-oxidation of Isoniazid Leads to Isonicotinic-Lysine Adducts on Human Serum Albumin.

    PubMed

    Meng, Xiaoli; Maggs, James L; Usui, Toru; Whitaker, Paul; French, Neil S; Naisbitt, Dean J; Park, B Kevin

    2015-01-20

    Isoniazid (INH), a widely used antituberculosis drug, has been associated with serious drug-induced liver injury (DILI). INH-modified proteins have been proposed to play important roles in INH DILI; however, it remains to be determined whether INH or reactive metabolites bind irreversibly to proteins. In this study, mass spectrometry was used to define protein modifications by INH in vitro and in patients taking INH therapy. When INH was incubated with N-acetyl lysine (NAL), the same isonicotinic-NAL (IN-NAL) adducts were detected irrespective of the presence or absence of any oxidative enzymes, indicating auto-oxidation may have been involved. In addition, we found that INH could also bind to human serum albumin (HSA) via an auto-oxidation pathway, forming isonicotinic amide adducts with lysine residues in HSA. Similar adducts were detected in plasma samples isolated from patients taking INH therapy. Our results show that INH forms protein adducts in the absence of metabolism.

  2. Lifetimes and stabilities of familiar explosive molecular adduct complexes during ion mobility measurements.

    PubMed

    McKenzie-Coe, Alan; DeBord, John Daniel; Ridgeway, Mark; Park, Melvin; Eiceman, Gary; Fernandez-Lima, Francisco

    2015-08-21

    Trapped ion mobility spectrometry coupled to mass spectrometry (TIMS-MS) was utilized for the separation and identification of familiar explosives in complex mixtures. For the first time, molecular adduct complex lifetimes, relative stability, binding energies and candidate structures are reported for familiar explosives. Experimental and theoretical results showed that the adduct size and reactivity, complex binding energy and the explosive structure tailor the stability of the molecular adduct complex. The flexibility of TIMS to adapt the mobility separation as a function of the molecular adduct complex stability (i.e., short or long IMS experiments/low or high IMS resolution) permits targeted measurements of explosives in complex mixtures with high confidence levels.

  3. A rescue act: Translesion DNA synthesis past N(2) -deoxyguanosine adducts.

    PubMed

    Nair, Deepak T; Kottur, Jithesh; Sharma, Rahul

    2015-07-01

    Genomic DNA is continually subjected to a number of chemical insults that result in the formation of modified nucleotides--termed as DNA lesions. The N(2) -atom of deoxyguanosine is particularly reactive and a number of chemicals react at this site to form different kinds of DNA adducts. The N(2) -deoxyguanosine adducts perturb different genomic processes and are particularly deleterious for DNA replication as they have a strong tendency to inhibit replicative DNA polymerases. Many organisms possess specialized dPols--generally classified in the Y-family--that serves to rescue replication stalled at N(2) -dG and other adducts. A review of minor groove N(2) -adducts and the known strategies utilized by Y-family dPols to replicate past these lesions will be presented here.

  4. Glottal configuration, acoustic, and aerodynamic changes induced by variation in suture direction in arytenoid adduction procedures.

    PubMed

    Inagi, Katsuhide; Connor, Nadine P; Suzuki, Tatsutoshi; Ford, Charles N; Bless, Diane M; Nakajima, Masami

    2002-10-01

    Arytenoid adduction is a phonosurgical procedure in which the arytenoid cartilages are approximated to reduce posterior glottal gap size and improve voice. Voice outcomes following arytenoid adduction are not always optimal. The goal of this study was to systematically vary suture direction and force of pull on the arytenoid cartilages in a human excised laryngeal model to determine the optimal combination of factors for reducing glottal gap and improving voice. Several factors demonstrated significant effects. Changes in suture direction and force of pull affected glottal configuration in both the horizontal and vertical planes. Increased force of pull on the muscular process resulted in increased adduction of the vocal process for all suture directions. Changes in suture direction and force of pull also affected acoustic and aerodynamic measures of induced voice. Therefore, voice outcomes can be optimized with arytenoid adduction if the vocal fold plane is accurately adjusted.

  5. Methods for synthesizing alane without the formation of adducts and free of halides

    DOEpatents

    Zidan, Ragaiy; Knight, Douglas A; Dinh, Long V

    2013-02-19

    A process is provided to synthesize an alane without the formation of alane adducts as a precursor. The resulting product is a crystallized .alpha.-alane and is a highly stable product and is free of halides.

  6. Profiling Cys34 Adducts of Human Serum Albumin by Fixed-Step Selected Reaction Monitoring*

    PubMed Central

    Li, He; Grigoryan, Hasmik; Funk, William E.; Lu, Sixin Samantha; Rose, Sherri; Williams, Evan R.; Rappaport, Stephen M.

    2011-01-01

    A method is described for profiling putative adducts (or other unknown covalent modifications) at the Cys34 locus of human serum albumin (HSA), which represents the preferred reaction site for small electrophilic species in human serum. By comparing profiles of putative HSA-Cys34 adducts across populations of interest it is theoretically possible to explore environmental causes of degenerative diseases and cancer caused by both exogenous and endogenous chemicals. We report a novel application of selected-reaction-monitoring (SRM) mass spectrometry, termed fixed-step SRM (FS-SRM), that allows detection of essentially all HSA-Cys34 modifications over a specified range of mass increases (added masses). After tryptic digestion, HSA-Cys34 adducts are contained in the third largest peptide (T3), which contains 21 amino acids and an average mass of 2433.87 Da. The FS-SRM method does not require that exact masses of T3 adducts be known in advance but rather uses a theoretical list of T3-adduct m/z values separated by a fixed increment of 1.5. In terms of added masses, each triply charged parent ion represents a bin of ±2.3 Da between 9.1 Da and 351.1 Da. Synthetic T3 adducts were used to optimize FS-SRM and to establish screening rules based upon selected b- and y-series fragment ions. An isotopically labeled T3 adduct is added to protein digests to facilitate quantification of putative adducts. We used FS-SRM to generate putative adduct profiles from six archived specimens of HSA that had been pooled by gender, race, and smoking status. An average of 66 putative adduct hits (out of a possible 77) were detected in these samples. Putative adducts covered a wide range of concentrations, were most abundant in the mass range below 100 Da, and were more abundant in smokers than in nonsmokers. With minor modifications, the FS-SRM methodology can be applied to other nucleophilic sites and proteins. PMID:21193536

  7. Malondialdehyde-acetaldehyde (MAA) adducted proteins bind to scavenger receptor A in airway epithelial cells.

    PubMed

    Berger, John P; Simet, Samantha M; DeVasure, Jane M; Boten, Jessica A; Sweeter, Jenea M; Kharbanda, Kusum K; Sisson, Joseph H; Wyatt, Todd A

    2014-08-01

    Co-exposure to cigarette smoke and ethanol generates malondialdehyde and acetaldehyde, which can subsequently lead to the formation of aldehyde-adducted proteins. We have previously shown that exposure of bronchial epithelial cells to malondialdehyde-acetaldehyde (MAA) adducted protein increases protein kinase C (PKC) activity and proinflammatory cytokine release. A specific ligand to scavenger receptor A (SRA), fucoidan, blocks this effect. We hypothesized that MAA-adducted protein binds to bronchial epithelial cells via SRA. Human bronchial epithelial cells (BEAS-2B) were exposed to MAA-adducted protein (either bovine serum albumin [BSA-MAA] or surfactant protein D [SPD-MAA]) and SRA examined using confocal microscopy, fluorescent activated cell sorting (FACS), and immunoprecipitation. Differentiated mouse tracheal epithelial cells (MTEC) cultured by air-liquid interface were assayed for MAA-stimulated PKC activity and keratinocyte-derived chemokine (KC) release. Specific cell surface membrane dye co-localized with upregulated SRA after exposure to MAA for 3-7 min and subsided by 20 min. Likewise, MAA-adducted protein co-localized to SRA from 3 to 7 min with a subsequent internalization of MAA by 10 min. These results were confirmed using FACS analysis and revealed a reduced mean fluorescence of SRA after 3 min. Furthermore, increased amounts of MAA-adducted protein could be detected by Western blot in immunoprecipitated SRA samples after 3 min treatment with MAA. MAA stimulated PKCε-mediated KC release in wild type, but not SRA knockout mice. These data demonstrate that aldehyde-adducted proteins in the lungs rapidly bind to SRA and internalize this receptor prior to the MAA-adducted protein stimulation of PKC-dependent inflammatory cytokine release in airway epithelium.

  8. Effect of Laterally Wedged Insoles on the External Knee Adduction Moment across Different Reference Frames

    PubMed Central

    Yamaguchi, Satoshi; Kitamura, Masako; Ushikubo, Tomohiro; Murata, Atsushi; Akagi, Ryuichiro; Sasho, Takahisa

    2015-01-01

    Objective Biomechanical effects of laterally wedged insoles are assessed by reduction in the knee adduction moment. However, the degree of reduction may vary depending on the reference frame with which it is calculated. The purpose of this study was to clarify the effect of reference frame on the reduction in the knee adduction moment by laterally wedged insoles. Methods Twenty-nine healthy participants performed gait trials with a laterally wedged insole and with a flat insole as a control. The knee adduction moment, including the first and second peaks and the angular impulse, were calculated using four different reference frames: the femoral frame, tibial frame, laboratory frame and the Joint Coordinate System. Results There were significant effects of reference frame on the knee adduction moment first and second peaks (P < 0.001 for both variables), while the effect was not significant for the angular impulse (P = 0.84). No significant interaction between the gait condition and reference frame was found in either of the knee adduction moment variables (P = 0.99 for all variables), indicating that the effects of laterally wedged insole on the knee adduction moments were similar across the four reference frames. On the other hand, the average percent changes ranged from 9% to 16% for the first peak, from 16% to 18% for the second peak and from 17% to 21% for the angular impulse when using the different reference frames. Conclusion The effects of laterally wedged insole on the reduction in the knee adduction moment were similar across the reference frames. On the other hand, Researchers need to recognize that when the percent change was used as the parameter of the efficacy of laterally wedged insole, the choice of reference frame may influence the interpretation of how laterally wedged insoles affect the knee adduction moment. PMID:26397375

  9. Ultrasensitive isolation, identification and quantification of DNA–protein adducts by ELISA-based RADAR assay

    PubMed Central

    Kiianitsa, Kostantin; Maizels, Nancy

    2014-01-01

    Enzymes that form transient DNA–protein covalent complexes are targets for several potent classes of drugs used to treat infectious disease and cancer, making it important to establish robust and rapid procedures for analysis of these complexes. We report a method for isolation of DNA–protein adducts and their identification and quantification, using techniques compatible with high-throughput screening. This method is based on the RADAR assay for DNA adducts that we previously developed (Kiianitsa and Maizels (2013) A rapid and sensitive assay for DNA–protein covalent complexes in living cells. Nucleic Acids Res., 41:e104), but incorporates three key new steps of broad applicability. (i) Silica-assisted ethanol/isopropanol precipitation ensures reproducible and efficient recovery of DNA and DNA–protein adducts at low centrifugal forces, enabling cell culture and DNA precipitation to be carried out in a single microtiter plate. (ii) Rigorous purification of DNA–protein adducts by a procedure that eliminates free proteins and free nucleic acids, generating samples suitable for detection of novel protein adducts (e.g. by mass spectroscopy). (iii) Identification and quantification of DNA–protein adducts by direct ELISA assay. The ELISA-based RADAR assay can detect Top1–DNA and Top2a–DNA adducts in human cells, and gyrase–DNA adducts in Escherichia coli. This approach will be useful for discovery and characterization of new drugs to treat infectious disease and cancer, and for development of companion diagnostics assays for individualized medicine. PMID:24914050

  10. Determinants of the variability of aflatoxin-albumin adduct levels in Ghanaians.

    PubMed

    Dash, B; Afriyie-Gyawu, E; Huebner, H J; Porter, W; Wang, J S; Jolly, P E; Phillips, T D

    2007-01-01

    Hepatocellular carcinoma (HCC) is a multifactorial disease with various host and environmental factors involved in its etiology. Of these, aflatoxin exposure has been established as an important risk factor in the development of HCC; the presence of aflatoxin-albumin (AA) adducts in the blood serves as a valuable biomarker of human exposure. In this study, the relationship between a variety of different HCC host factors and the incidence of AA adduct levels was examined in a Ghanaian population at high risk for HCC. These factors included age, gender, hepatitis virus B (HVB) and hepatitis C virus (HCV) status, and genetic polymorphisms in both microsomal epoxide hydrolase (mEH) and glutathione S-transferases (GSTs). Blood samples were analyzed for AA adducts and HBV and HCV status. GSTM1 and GSTT1 deletion polymorphisms and mEH exon 3 and exon 4 single-nucleotide polymorphisms (SNPs) were determined from urine samples. In univariate analysis, age, HBV and HVC status, and GSTT1 and mEH exon 3 genotypes were not associated with AA adduct levels. However, mean adduct levels were significantly higher in both females and individuals typed heterozygous for mEH exon 4 (vs. wild types). Stratification analysis also showed that gender along with mEH exon 4 genotype and HBV status had a significant effect on adduct levels. Both females typed HBsAg+ and males with mEH exon 4 heterozygote genotypes showed significantly higher adduct levels as compared to the HBsAg- and wild types, respectively. Understanding the relationships between these host factors and the variability in aflatoxin-adduct levels may help in identifying susceptible populations in developing countries and for targeting specific public health interventions for the prevention of aflatoxicoses in populations with HCC and chronic liver diseases. PMID:17162498

  11. Translesion synthesis past acrolein-derived DNA adducts by human mitochondrial DNA polymerase γ.

    PubMed

    Kasiviswanathan, Rajesh; Minko, Irina G; Lloyd, R Stephen; Copeland, William C

    2013-05-17

    Acrolein, a mutagenic aldehyde, is produced endogenously by lipid peroxidation and exogenously by combustion of organic materials, including tobacco products. Acrolein reacts with DNA bases forming exocyclic DNA adducts, such as γ-hydroxy-1,N(2)-propano-2'-deoxyguanosine (γ-HOPdG) and γ-hydroxy-1,N(6)-propano-2'-deoxyadenosine (γ-HOPdA). The bulky γ-HOPdG adduct blocks DNA synthesis by replicative polymerases but can be bypassed by translesion synthesis polymerases in the nucleus. Although acrolein-induced adducts are likely to be formed and persist in mitochondrial DNA, animal cell mitochondria lack specialized translesion DNA synthesis polymerases to tolerate these lesions. Thus, it is important to understand how pol γ, the sole mitochondrial DNA polymerase in human cells, acts on acrolein-adducted DNA. To address this question, we investigated the ability of pol γ to bypass the minor groove γ-HOPdG and major groove γ-HOPdA adducts using single nucleotide incorporation and primer extension analyses. The efficiency of pol γ-catalyzed bypass of γ-HOPdG was low, and surprisingly, pol γ preferred to incorporate purine nucleotides opposite the adduct. Pol γ also exhibited ∼2-fold lower rates of excision of the misincorporated purine nucleotides opposite γ-HOPdG compared with the corresponding nucleotides opposite dG. Extension of primers from the termini opposite γ-HOPdG was accomplished only following error-prone purine nucleotide incorporation. However, pol γ preferentially incorporated dT opposite the γ-HOPdA adduct and efficiently extended primers from the correctly paired terminus, indicating that γ-HOPdA is probably nonmutagenic. In summary, our data suggest that acrolein-induced exocyclic DNA lesions can be bypassed by mitochondrial DNA polymerase but, in the case of the minor groove γ-HOPdG adduct, at the cost of unprecedented high mutation rates.

  12. [Mass spectrometric analysis of polycyclic aromatic hydrocarbons adducted to DNA]. Final report

    SciTech Connect

    Barofsky, D.F.

    1992-12-31

    Studies described herein sought and to synthesize PAH-adducted residues of DNA to serve as models for carrying out the mass spectrometric studies; to construct and test a high performance, pulsed ion bombardment, time-of-flight (TOF) mass spectrometer; to initiate an investigation of the efficacy of using thin wire sample holders to increase sensitivity and focused ion beam bombardment to increase ion yield and ion transmission; and to initiate an investigation of sensitivity enhancing matrices for PAH-adducted DNA.

  13. Quantitative changes in endogenous DNA adducts correlate with conazole in vivo mutagenicity and tumorigenicity.

    PubMed

    Ross, Jeffrey A; Leavitt, Sharon A; Schmid, Judith E; Nelson, Garret B

    2012-09-01

    The mouse liver tumorigenic conazole fungicides triadimefon and propiconazole have previously been shown to be in vivo mouse liver mutagens in the Big Blue™ transgenic mutation assay when administered in feed at tumorigenic doses, whereas the nontumorigenic conazole myclobutanil was not mutagenic. DNA sequencing of the mutants recovered from each treatment group as well as from animals receiving control diet revealed that propiconazole- and triadimefon-induced mutations do not represent general clonal expansion of background mutations, and support the hypothesis that they arise from the accumulation of endogenous reactive metabolic intermediates within the liver in vivo. We therefore measured the spectra of endogenous DNA adducts in the livers of mice from these studies to determine if there were quantitative or qualitative differences between mice receiving tumorigenic or nontumorigenic conazoles compared to concurrent control animals. We resolved and quantitated 16 individual adduct spots by (32)P postlabelling and thin layer chromatography using three solvent systems. Qualitatively, we observed the same DNA adducts in control mice as in mice receiving conazoles. However, the 13 adducts with the highest chromatographic mobility were, as a group, present at significantly higher amounts in the livers of mice treated with propiconazole and triadimefon than in their concurrent controls, whereas this same group of DNA adducts in the myclobutanil-treated mice was not different from controls. This same group of endogenous adducts were significantly correlated with mutant frequency across all treatment groups (P = 0.002), as were total endogenous DNA adduct levels (P = 0.005). We hypothesise that this treatment-related increase in endogenous DNA adducts, together with concomitant increases in cell proliferation previously reported to be induced by conazoles, explain the observed incr