Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q86TM3 (cage)
 29,987 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chlorinated phenols, which are used primarily as wood preservatives and fungicides, are present in most air, water, and soil samples in industrialized areas as well as in the urine of most people. We have examined the ability of phenol and the 19 isomers of chlorophenol to induce DNA damage using the Microscreen prophage-induction assay in Escherichia coli. Seven of the isomers (2,3,4,-tri, 2,4,5-tri, 3,4,5-tri, 2,3,4,5-tetra, 2,3,6-tri, 2,4,6-tri, and pentachlorophenol) induced prophage lambda in the presence of S9, with the first three being approximately 10 times more potent than the last three. The more potent isomers have either one or no chlorine atom ortho to the OH group; whereas the less potent isomers have two chlorine atoms ortho to the OH group. Although none of the 20 compounds is mutagenic in Salmonella, the prophage-induction results agree with findings by others that most of these seven isomers are clastogenic, are associated with cancer and chromosomal aberrations in humans (pentachlorophenol), and are carcinogenic in rodents (2,4,6-tri and pentachlorophenol). A likely basis for the genotoxicity of the seven isomers involves the metabolism of the parent isomer to a chlorohydroquinone, which can form a chlorobenzosemiquinone in the presence of oxygen. These two metabolites can produce free radicals that can cause DNA strand breaks, resulting in prophage induction in E. coli or, possibly, the chromosomal aberrations/cancer associated with human exposure to chlorophenols.
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PMID:Induction of prophage lambda by chlorophenols. 213 84

Chlorine dioxide (ClO2), an alternative to chlorine for drinking water disinfection, has been implicated as a potential antithyroid agent (Bercz et al., 1982). Because antithyroid compounds are known to alter neurobehavioral development, the present study was designed to determine if perinatal exposure to ClO2 affects behavioral activity in rat pups. The activity cage system was designed to monitor the development of locomotor activity of a litter of pups between ages 14-21 d. Pups were exposed to ClO2 either directly, by gavaging 14 mg/kg . from age 5 to 20 d, or indirectly via their dams' drinking water in concentrations of 2, 20, or 100 mg/l from gestation to weaning (21 d postpartum). Although the activity of the indirectly exposed group was not different from controls, the gavaged group showed significantly depressed activity for d 18 and 19 postpartum. The T4 levels of the 21-d-old pups was significantly depressed in the 100-mg/l ClO2 group. The gavaged pups showed an even greater T4 depression, which correlates with their activity levels. These data support the hypothesis that ClO2 affects thyroid function and suggests that a slight depression in T4 can result in developmental delays.
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PMID:Effects of chlorine dioxide on thyroid function in neonatal rats. 400 37

The degradation of 1-14C-chlorododecanes to 14CO2 in C57BL mice was studied. 1-14C-Chlorododecane-injected mice were transferred to an all-glass metabolism cage and the exhaled air was monitored for 14CO2. Pretreatment with cytochrome P-450 inhibitors resulted in a marked decrease in the rate of 14CO2-formation, when measured as peak 14CO2-exhalation rate (PER): After piperonyl butoxide pretreatment the degradation rate of a high-chlorinated 14C-dodecane (PCDD II; 68% Cl w/w) to 14CO2 was 16% of control, and after metyrapone pretreatment 40%. It was also shown that piperonyl butoxide pretreatment decreased the rate of 14CO2-formation, and the amount of 14CO2 formed, in proportion to the chlorine content of four differently chlorinated dodecanes. The cytochrome P-450 inducer phenobarbital moderately (PER 152%) increased the rate of 14CO2-formation from PCDD II, whereas 3-methylcholanthrene and several technical grade chlorinated paraffins generally gave less or no inductive effects. Also the cumulative 14CO2-exhalation, measured during six hours (CE-6), was inhibited and induced after the above pretreatments. The results indicate a cytochrome P-450-dependent degradation of C12-chloroalkanes to 14CO2 in vivo. The degradation via cytochrome P-450 seems to be relatively more important for higher chlorinated alkanes.
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PMID:Chlorinated paraffins: effect of some microsomal enzyme inducers and inhibitors on the degradation of 1-14C-chlorododecanes to 14CO2 in mice. 643 40

Photolysis of 1-fluoro-2-halo-1,2-diphenylethanes was studied in solutions of tetrahydrofuran, acetonitrile, and cyclohexane. The effect of free radical inhibitor and metal hydrides on products formation as well as their ratio was analyzed to elucidate the reaction pathway. In the first step homolytic C-X bond cleavage occurs from a single excited state, resulting in a biradical pair. Further reaction path depends on the type of the halogen bonded and on the solvent polarity. Electron transfer within the radical pair cage is apparently more rapid for bromides than for chlorides and is opposite as expected on the basis of the relative electronegativities of chlorine and bromine. As radicals approach each other, they fall into ionic or radical product channels. This is influenced by solvent polarity, resulting in the larger yield of ionic products in the case of acetonitrile as in the case of less polar cyclohexane.
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PMID:Photolysis of bromo- and chloro-substituted benzyl derivatives. Competition between ionic and radical pathways 1103 Oct 6

Photolysis, at lambda >/= 310 nm (DeltaE < 387 kJ mol(-1)), of acryloyl chloride 1 isolated in argon matrixes at 10 K yields 3-chloro-1,2-propenone 4 through 1,3-chlorine migration. There is no evidence of cyclopropenone or propadienone formation. 4 is also synthesized by irradiation of 3-chloropropanoyl chloride (lambda >/= 230 nm) isolated in argon matrix at 10 K. Identification is performed by comparison of experimental FT-IR spectrum with calculated ones (ab initio calculations at the 6-31G level). Irradiation of 1 at lambda >/= 230 nm induces the photolysis of 4 which breaks into CO and the postulated transient 2-chloroethylidene 5 and/or into propadienone 2 complexed by HCl. The transient 5 collapses to form ground-state vinyl chloride 6 by 1,2 hydrogen migration. In the next step, 2 loses CO to form a new transient assumed to be vinylidene 7 which yields ethyne by intramolecular isomerization process and vinyl chloride by intermolecular reaction with HCl trapped in the same cage. CO, HCl, ethyne, and vinyl chloride are the final reaction products. Modeling of the 1,3 chlorine migration process from 1 using ab initio calculations at the MP2/6-31G level is performed in the ground state (S(0)) and the first singlet excited state (S(1)). The reaction energy value for an S(1) (509 kJ/mol) state process is higher than for an S(0) process (207.2 kJ/mol), these theoretical results suggesting the reaction take place in the ground state.
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PMID:Photolysis of Matrix-Isolated Acryloyl Chloride: 1,3 Chlorine Migration and Further Evolutions. 1167 5

The mechanism of the Gibbs reaction, a colorimetric phenol assay that applies N-chlorobenzoquinone imines 1 in an aqueous basic medium, was investigated. It is concluded that N-chloroimine radical anion 7 generated in a single electron transfer (SET) from the anion of phenol 4 to N-chloroimine 1 can produce indophenol dye 3 in three distinct routes. For more reactive reagent-substrate pairs, a route is proposed that involves a fast combination of the radical pair in the solvent cage and, consequently, the total rate of which exhibits a pH-independent second-order kinetics, as does the preceding SET itself. For less reactive reagents, a route is proposed in which the N-chloroimine radical anion 7 escapes from the solvent cage to initiate a chain reaction, evidenced by its characteristic kinetics. It has been found in the kinetic experiments that during propagation the chlorine of the chain carrier N-chloroimine radical anion 7 is substituted by the anion of 4 in a bimolecular rate-determining step. Therefore, the mechanism of the chain reaction is termed S(RN)2. In the case when the anion of 4 is less active, a competitive reaction along a third route can proceed in which the N-haloimine radical anion 7 yields benzoquinone imine 6 by the elimination of halogenide and the abstraction of an H-atom from the medium. Compound 6 is also known to give indophenol 3 with a second-order but pH-dependent rate that is considerably faster than the rate in the first route. On the basis of the different kinetic characteristics outlined above a clear distinction can be made among these three pathways. In this paper, evidence is also presented for the initiating SET. Furthermore, it is of high importance that the N-haloimine radical anion 7 can also be generated from reagent 1 using external electron donors and, independently of its origin, it can be spin trapped with 2,2,6,6-tetramethylpiperidine-N-oxyl.
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PMID:Mechanism of the Gibbs Reaction. Part 4.(1) Indophenol Formation via N-Chlorobenzoquinone Imine Radical Anions. The Aza-S(RN)2 Chain Reaction Mechanism. Chain Initiation with 1,4-Benzoquinones and Cyanide Ion. 1167 54

The practice of chlorine disinfection of drinking water to reduce microbial risks provides substantial benefits to public health. However, increasing concern around potential risks of cancer associated with exposure to chlorinated disinfection byproducts confuses this issue. This article examines the science agenda regarding chlorinated disinfection byproducts (CDBP) and cancer in Canada and the United States, focusing on the social construction of scientific knowledge claims and evidence. Data for this analysis were obtained from published documents as well as from in-depth interviews with epidemiologists and toxicologists centrally involved with the issue in both countries. Results of the analysis suggest that toxicological scientists want to close the door on the "chloroform issue" due to increasing evidence that chloroform is safe at low doses, because epidemiological scientists can no longer move forward the cancer science until significant improvements can be made in assessing human exposures, and because the scientific foci of research on DBP have shifted accordingly. Further, a distinction emerges in terms of how scientific uncertainties are interpreted when they cross-cut disciplines in the context of human health risk assessment. We suggest this tension reflects a balance of how uncertainty and authorities are managed in a mandated science-policy domain. Sufficient evidence was provided to keep the DBP issue on the regulatory agenda and to generate additional research, yet authorities and concomitant interpretations of uncertainty were contested. Such science generation and contestation inevitably influences complex risk assessment processes with respect to what water-related health risks are addressed and how.
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PMID:Constructing scientific authorities: issue framing of chlorinated disinfection byproducts in public health. 1222 51

The molecular structures of 1-bromo-pentaborane(9) and 2-bromo-pentaborane(9) in the gas phase have been determined by electron diffraction and ab initio and DFT computational methods. Computational methods have also been applied to the fluoro and chloro analogues, to 1,2-dibromo-pentaborane(9), and to the parent unsubstituted borane. The electronic effects of halogen substitution on the borane cage are remarkably small, particularly for chlorine and bromine substituents, and steric effects are also minimal, even in the compound with two bromine atoms. The largest effects are (a) lengthening of B((base))-B((apex)) bonds adjacent to the halogen in the 2-isomers, with an associated shortening of the opposite base-apex bond, (b) shortening of the B((base))-B((apex)) bond in the 1-fluoro compound, and (c) increase of the B((base))-B((apex))-F angle in 1-F-B(5)H(8), but a decrease in this angle in the 2-bromo compounds.
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PMID:The molecular structures of pentaborane(9) with halogen substituents in apical and basal positions, determined by electron diffraction and theoretical calculations. 1525 68

We study the hydrogen abstraction reaction from pentane by chlorine radicals using four different experimental approaches. We use two different solvents (CH2Cl2 and CCl4) and two different chlorine atom sources (photodissociation of dissolved Cl2 and two-photon photolysis of the solvent) to investigate their effects on the recombination and reactivity of the chlorine radical. All four experimental schemes involve direct probing of the transient chlorine population via a charge transfer transition with a solvent molecule. In one of the four approaches, photolysis of Cl2 in dichloromethane, we also monitor the nascent reaction products (HCl) by transient vibrational spectroscopy. Probing both the reactants and the products provides a comprehensive view of this bimolecular reaction in solution. Between one-third and two-thirds of the chlorine radicals that initially escape the solvent cage undergo diffusive geminate recombination with their partner radical (either another chlorine atom or the solvent radical). The rest react with pentane with the bimolecular rate constants k(bi) = (9.5 +/- 0.7) x 10(9) M(-1) s(-1) in CH2Cl2 and k(bi) = (7.4 +/- 2) x 10(9) M(-1) s(-1) in CCl4. The recombination yield phi(rec) depends on both the chlorine atom precursor and the solvent and is larger in the more viscous carbon tetrachloride solutions. The bimolecular reaction rate k(bi) depends only on the solvent and is consistent with a nearly diffusion-limited reaction.
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PMID:Time-resolved spectroscopic study of the reaction Cl + n-C5H12 --> HCl + C5H11 in solution. 1650 30

The matrix-isolation technique has been combined with infrared spectroscopy to identify and characterize the products formed by irradiation of cage-paired CrCl(2)O(2) and a series of chloroethenes, C(2)H(x)()Cl(y)() (x + y = 4). For each system, oxygen-atom transfer occurred upon irradiation, yielding the corresponding acetyl chloride derivative and the Cl(2)CrO species. The products were formed in the same matrix cage and strongly interacted to form a distinct molecular complex after formation. Three different modes of interaction were explored computationally: eta(1) to the oxygen atom, eta(2) to the C=O bond, and eta(1) to the chlorine atom. In addition, a five-membered metallocycle and the chloroepoxide species were considered. No evidence was obtained for the chloroacetaldehyde derivative, indicating the occurrence of oxygen-atom attack at the more substituted carbon of the chloroethene. Evidence tentatively supporting the formation of the metallocycle was obtained as well. Theoretical calculations indicated that the acetyl chloride derivative was approximately 10 kcal/mol more stable than the corresponding chloroacetaldehyde species for each system at the B3LYP/6-311++g(d,2p) level of theory. The binding energy of each of the complexes was also found to be near 10 kcal/mol at this level of theory.
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PMID:Matrix isolation and theoretical study of the photochemical reaction of CrCl2O2 with chloroethenes. 1683 69


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