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PubMed2001

Cherry angiomas associated with exposure to bromides.

Cherry angiomas are the most common vascular proliferation; however, little is known about the pathogenesis and etiology of these lesions. We present two laboratory technicians who were exposed to brominated compounds for prolonged periods and who developed multiple cherry angiomas on the trunk and extremities. We suggest that the association between exposure to bromides and cherry angiomas should be investigated by a controlled study.

Adult↗
PubMed1986

Interaction of halocompounds with nucleic acids.

The binding of epichlorohydrin, 1,2-dichloroethane, 1,2-dibromoethane, chlorobenzene, bromobenzene, and benzene to nucleic acids and proteins of different murine organs was studied in in vivo and in vitro systems. The extent of in vivo enzymatic activation of brominated compounds was higher than that of chlorinated chemicals. Aryl halides were bound mainly to liver DNA whereas interaction of alkyl halides with DNA of liver, kidney, and lung gave rise to similar binding extent. In vitro activation of all chemicals was mediated by microsomal P-450-dependent mixed function oxidase system which is present in rat and mouse liver and, in smaller amount, in mouse lung. Activation of alkyl halides by liver cytosolic GSH-transferases even occurred. The relative reactivity of chemicals in vivo, expressed as Covalent Binding Index (CBI) to rat liver DNA, was: 1,2-dibromoethane greater than bromobenzene greater than 1,2-dichloroethane greater than chlorobenzene greater than epichlorohydrin greater than benzene. On the whole, it agreed with in vitro activation of chemicals, with genotoxicity data from other short-term assays and also with oncogenicity of benzene, epichlorohydrin, 1,2-dichloroethane, and 1,2-dibromoethane. CBI values of chlorobenzene and bromobenzene gave the first clear evidence of genotoxicity and of possible carcinogenicity of these two chemicals.

Animals↗
PubMed1996

Inhibitors of acyl-CoA: cholesterol acyltransferase. II. Preparation and hypocholesterolemic activity of optically active dibenz[b,e]oxepin-11-carboxanilides.

In a previous paper, we reported a novel inhibitor of acyl-CoA: cholesterol acyltransferase (ACAT), 2-bromo-N-(2,6-diisopropylphenyl)-6,11- dihydrodibenz[b,e]oxepin-11-carboxamide (1). In this work, we prepared both enantiomers and tested them for ability to inhibit ACAT (liver microsomes from cholesterol-fed rabbits) in vitro and to decrease serum total cholesterol in cholesterol-fed golden hamsters in vivo. The precursor carboxylic acid 4 was optically resolved with cinchonidine. The obtained (-)- and (+)-4 were converted to (-)- and (+)-1 without racemization, respectively. The enantiomer (-)-1 showed potent ACAT inhibitory activity in vitro with an IC50 value of 8 nM and was approximately 10-fold more active than (+)-1. Furthermore, (-)-1 showed strong hypocholesterolemic activity in vivo, whereas (+)-1 was inactive. A molecular modeling study showed that the difference of ACAT inhibitory activity between the enantiomers was derived from the spatial alignment of the bromine. Compound (-)-1 was selected for further evaluation as KW-3033.

Animals↗
PubMed2001

Assessing exposure to disinfection by-products in women of reproductive age living in Corpus Christi, Texas, and Cobb county, Georgia: descriptive results and methods.

We conducted a field study in Corpus Christi, Texas, and Cobb County, Georgia, to evaluate exposure measures for disinfection by-products, with special emphasis on trihalomethanes (THMs). Participants were mothers living in either geographic area who had given birth to healthy infants from June 1998 through May 1999. We assessed exposure by sampling blood and water and obtaining information about water use habits and tap water characteristics. Two 10-mL whole blood samples were collected from each participant before and immediately after her shower. Levels of individual THM species (chloroform, bromodichloromethane, dibromochloromethane, and bromoform) were measured in whole blood [parts per trillion (pptr)] and in water samples (parts per billion). In the Corpus Christi water samples, brominated compounds accounted for 71% of the total THM concentration by weight; in Cobb County, chloroform accounted for 88%. Significant differences in blood THM levels were observed between study locations. For example, the median baseline blood level of bromoform was 0.3 pptr and 3.5 pptr for participants in Cobb County and Corpus Christi, respectively (p = 0.0001). Differences were most striking in blood obtained after showering. For bromoform, the median blood levels were 0.5 pptr and 17 pptr for participants in Cobb County and Corpus Christi, respectively (p = 0.0001). These results suggest that blood levels of THM species vary substantially across populations, depending on both water quality characteristics and water use activities. Such variation has important implications for epidemiologic studies of the potential health effects of disinfection by-products.

Activities of Daily Living↗
PubMed2003

Chlorination by-products in drinking water and menstrual cycle function.

We analyzed data from a prospective study of menstrual cycle function and early pregnancy loss to explore further the effects of trihalomethanes (THM) on reproductive end points. Premenopausal women ((italic)n(/italic) = 403) collected urine samples daily during an average of 5.6 cycles for measurement of steroid metabolites that were used to define menstrual parameters such as cycle and phase length. Women were asked about consumption of various types of water as well as other habits and demographics. A THM level was estimated for each cycle based on residence and quarterly measurements made by water utilities during a 90-day period beginning 60 days before the cycle start date. We found a monotonic decrease in mean cycle length with increasing total THM (TTHM) level; at > 60 microg/L, the adjusted decrement was 1.1 days [95% confidence interval (CI), -1.8 to -0.40], compared with less than or equal to 40 microg/L. This finding was also reflected as a reduced follicular phase length (difference -0.94 day; 95% CI, -1.6 to -0.24). A decrement in cycle and follicular phase length of 0.18 days (95% CI, -0.29 to -0.07) per 10 microg/L unit increase in TTHM concentration was found. There was little association with luteal phase length, menses length, or cycle variability. Examining the individual THMs by quartile, we found the greatest association with chlorodibromomethane or the sum of the brominated compounds. Incorporating tap water consumption showed a similar pattern of reduced cycle length with increasing TTHM exposure. These findings suggest that THM exposure may affect ovarian function and should be confirmed in other studies.

Abortion, Spontaneous↗
PubMed2004

Dietary accumulation and metabolism of polybrominated diphenyl ethers by juvenile carp (Cyprinus carpio).

Polybrominated diphenyl ethers (PBDEs) are hydrophobic organic contaminants with properties and nomenclature similar to polychlorinated biphenyls (PCBs). While much information is available on the bioaccumulation and pharamcokinetics of PCBs, little information is available on PBDEs. In this study, juvenile carp were exposed to a diet spiked with a cocktail of four BDE congeners (2,4,4'-tribromoDE [BDE 28], 2,2',4,4'-tetrabromoDE [BDE 47], 2,2',4,4',5-pentabromoDE [BDE 99], and 2,2',4,4',5,5'hexabromoDE [BDE 153]) for 60 d followed by a 40-d depuration period. As a positive control, three PCB congeners with similar log K(ow), values (2,2',5,5'-tetrachlorobiphenyl [PCB 52], 2,2',4,4', 5,5'-hexachlorobiphenyl [PCB 153], and 2,2',3,4,4',5,5'-heptachlorobiphenyl [PCB 180]) were included in the cocktail to compare their assimilation and fate with the model BDE congeners. Concentrations of BDEs and PCBs were monitored in whole-fish tissues and liver tissues over the duration of the experiment. In addition, blood serum samples were taken and pooled among replicates to determine if any phenolic metabolites of BDE and PCBs were formed. Rapid assimilation of BDE 47 was observed relative to all other BDE and PCB congeners, whereas apparently no accumulation of BDE 99 occurred over the course of the experiment. Assimilation efficiencies for BDE 47 suggest that approximately 100% of the BDE 47 exposure was absorbed by carp tissues after 60 d. However, based on the time course of BDE 47 assimilation, it is improbable that all BDE 47 was assimilated; more likely, production of BDE 47 in carp tissues occurred as a result of debromination of higher-brominated compounds, possibly BDE 99. The net assimilation efficiencies of BDE 28 and BDE 153 were also apparently low (20 and 4%, respectively) relative to the three PCBs (40% assimilated) examined in this study. The low assimilation efficiency and high depuration rates for BDEs suggest a higher potential for biotransformation. While all three PCB compounds displayed very similar assimilation and depuration rates, three of the four BDE compounds displayed significantly different assimilation rates among BDE congeners and relative to the PCBs. This study suggests that BDEs have significantly different fate dynamics relative to PCBs in wild carp and likely other species of fish.

Animals↗
PubMedDate not supplied

[Synthesis of 5-azido-3-nitro-omega-bromo-acetophenone- a photochemically active bifunctional reagent for the cross-linking of biopolymers].

The photochemically activatable heterobifunctional reagent 5-azido-3-nitro-omega-bromo-acetophenone (3) was synthesized by condensation of 3,5-dinitrobenzoyl chloride with diethyl malonate, acid-catalyzed decarboxylation of the formed malonester derivative 1 to 3,5-dinitro-acetophenone (2a), selective reduction of one nitro group in 2a to 5-amino-3-nitro-acetophenone (2b) and diazotization to 2c. Nucleophilic displacement of the diazonium group in 2c by sodium azide forms 5-azido-3-nitro-acetophenone (2d) which gives 3 after bromination. Compound 3 is photochemically labile and forms an highly reactive nitrene during ultraviolet irradiation. Since compound 3 is able to alkylate amino- or mercapto-groups of amino acids or nucleosides via its bromoacetyl residue, the bifunctional reagent 3 should cross link proteins or nucleic acids after nitrene generation.

Acetophenones↗
PubMed1991

Effects of bromowillardiine and willardiine on non-N-methyl-D-aspartate receptors in postnatal rat hippocampal neurons.

The physiology and pharmacology of willardiine and bromowillardiine, structural analogues of quisqualate, were studied in cultured postnatal rat hippocampal neurons using whole-cell voltage-clamp techniques. These agonists appear to act at a shared non-N-methyl-D-aspartate (non-NMDA) receptor-channel complex and gate nonselective cationic currents. Willardiine currents desensitize rapidly and to a much greater degree than bromowillardiine currents. In addition, the brominated compound produces steady state currents that are 5 times larger than those produced by willardiine at saturation. Bromowillardiine is also a more efficacious excitotoxin, producing about 3-fold greater acute neuronal damage than willardiine at saturating concentrations. These results suggest that agonist structure affects the ability of non-NMDA agonists to induce desensitization and add support to the hypothesis that receptor desensitization serves to limit acute excitotoxicity in cultured neurons.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed2006

In vitro and in vivo analysis of the thyroid system-disrupting activities of brominated phenolic and phenol compounds in Xenopus laevis.

We investigated the effects of the brominated phenolic and phenol compounds, some of which are brominated flame retardants, on the binding of (125)I-3,3',5-L-triiodothyronine ((125)I-T(3)) to purified Xenopus laevis transthyretin (xTTR) and to the ligand-binding domain of X. laevis thyroid hormone receptor beta (xTR LBD), on the induction of a T(3)-responsive reporter gene in a recombinant X. laevis cell line (XL58-TRE-Luc) and on T(3)-induced or spontaneous metamorphosis in X. laevis tadpoles. Of the brominated phenolic and phenol compounds tested, 3,3',5-tribromobisphenol A and 3,3'-dibromobisphenol A were the most potent competitors of (125)I-T(3) binding to xTTR and the xTR LBD, respectively. Structures with a bromine in either ortho positions with respect to the hydroxy group competed more efficiently with T(3) binding to xTTR and the xTR LBD. 3,3',5-Tribromobisphenol A and 3,3',5,5'-tetrabromobisphenol A, at 0.1-1.0 microM, exerted both T(3) agonist and antagonist activities in the T(3)-responsive reporter gene assay. Sera obtained from fetal bovine and bullfrog tadpoles weakened the T(3) agonist and antagonist activities of 3,3',5-tribromobisphenol A, but not the T(3) antagonist activity of o-t-butylphenol, for which xTTR has no significant affinity. The T(3) agonist and antagonist activities of 0.5 microM 3,3',5-tribromobisphenol A were confirmed in the in vivo, short-term gene expression assay in premetamorphic X. laevis tadpoles using endogenous, T(3)-responsive genes as molecular markers. Our results suggest that 3,3',5-tribromobisphenol A affects T(3) binding to xTTR and xTR and that it interferes with the intracellular T(3) signaling pathway.

Animals↗
PubMed1975

A review of bromine determination in foods.

Organic compounds containing bromine, including methyl bromide, ethylene dibromide, and 1,2-dibromo-3-chloropropane, have been used extensively for the fumigation of foods, or soils in which foods grow, making it necessary to determine residues of bromine and bromine-containing organic compounds. A large number of methods for the determination of bromine in foods, as organic, inorganic, and combined total bromide, have been developed. In methods for organic bromide, the bromine is converted to the inorganic form for measurement by titration, photometry, or other means. In recent years, instrumental methods have been developed in which the total bromine in the sample is determined, regardless of the state in which it exists. X-ray fluorescence and neutron activation analysis are the 2 instrumental methods used most widely. Residue data are presented for some typical bromine-containing samples.

Activation Analysis↗
PubMed2000

Potent competitive interactions of some brominated flame retardants and related compounds with human transthyretin in vitro.

Brominated flame retardants such as polybrominated diphenyl ethers (PBDEs), pentabromophenol (PBP), and tetrabromobisphenol A (TBBPA) are produced in large quantities for use in electronic equipment, plastics, and building materials. Because these compounds have some structural resemblance to the thyroid hormone thyroxine (T(4)), it was suggested that they may interfere with thyroid hormone metabolism and transport, e.g., by competition with T(4) on transthyretin (TTR). In the present study, we investigated the possible interaction of several brominated flame retardants with T(4) binding to TTR in an in vitro competitive binding assay, using human TTR and 125 I-T(4) as the displaceable radioligand. Compounds were tested in at least eight different concentrations ranging from 1.95 to 500 nM. In addition, we investigated the structural requirements of these and related ligands for competitive binding to TTR. We were able to show very potent competition binding for TBBPA and PBP (10.6- and 7.1-fold stronger than the natural ligand T(4), respectively). PBDEs were able to compete with T(4)-TTR binding only after metabolic conversion by induced rat liver microsomes, suggesting an important role for hydroxylation. Brominated bisphenols with a high degree of bromination appeared to be more efficient competitors, whereas chlorinated bisphenols were less potent compared to their brominated analogues. These results indicate that brominated flame retardants, especially the brominated phenols and tetrabromobisphenol A, are very potent competitors for T(4) binding to human transthyretin in vitro and may have effects on thyroid hormone homeostasis in vivo comparable to the thyroid-disrupting effects of PCBs.

Animals↗