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PubMed2006

Identification and quantification of polybrominated hexahydroxanthene derivatives and other halogenated natural products in commercial fish and other marine samples.

During routine analysis of commercial fish on halogenated pollutants, an unknown tribromo component (TriBHD) was initially detected as an abundant peak in sample extracts from the Mediterranean Sea. The molecular formula was established to be C16H19Br3O by gas chromatography with electron ionization high-resolution mass spectrometry (GC/EI-HRMS). GC/EI-MS data were virtually identical with a polybrominated hexahydroxanthene derivative (PBHD) previously isolated from an Australian sponge species known to occur in the Mediterranean Sea as well. A tetrabromo isomer (TetraBHD) was also found in the fish samples. The concentrations of TriBHD and other halogenated compounds in commercial fish (sea bass, gilt head bream, anchovy, sardine, and salmon) were estimated with GC/electron capture detection (ECD). Using the ECD response of trans-nonachlor, the concentration of TriBHD reached up to 90 ng/g lipid weight and accounted for up to >90% of the concentration of p,p'-DDE, which was the most abundant peak in the most samples investigated. On the basis of the GC/ECD response, TetraBHD amounted for approximately 1/7 of TriBHD in all fish samples investigated. The sample with the highest content was a green-lipped mussel from New Zealand (236 ng/g lipid weight). The halogenated natural products TBA, Q1, and MHC-1 were also present in most of the samples. We assume that the bulk of the residues in fish from aquaculture may originate from algae and sponges living in proximity of the fish farms. Detection of TriBHD and TetraBHD in blubber of a monk seal (Monachus monachus) suggests that both HNPs may reach the top predators of food webs and thus also humans.

Animals↗

PubMed2006

Dehalogenation of halogenated fumigants by polysulfide salts.

Halogenated fumigants are among the most heavily used pesticides in agriculture. Because of their high mobility and toxicological characteristics, the contamination of air or groundwater by these compounds has been a great environmental concern. In this study, we investigated dehalogenation of several halogenated fumigants by polysulfides. The reaction of polysulfides and methyl iodide (MeI), 1,3-dichloropropene (1,3-D), and chloropicrin (CP) was very rapid. When the initial fumigant and polysulfide concentrations were both 0.2 mM, the observed 50% disappearance time values (DT50) of MeI, cis-1,3-D, and trans-1,3-D were 27.2, 29.6, and 102 h, respectively. When the initial polysulfide concentration was 1.0 mM, the corresponding DT50 values were only 2.2, 1.6, and 3.8 h. Under similar conditions, the reaction with CP was even more rapid than with the other fumigants. In 0.2 mM polysulfide solution, more than 90% of the spiked CP disappeared in 1 h after the initiation of the reaction. The reaction between fumigants and polysulfides also progressed at enhanced rates when the polysulfide solution was initially purged with nitrogen. Analysis of reaction kinetics and initial products suggests that the reaction is SN2 nucleophilic substitution for MeI and 1,3-D but likely reductive dehalogenation for CP. Given the high reactivity of polysulfide salts toward halogenated fumigants, this reaction may be used as a pollution mitigation strategy, such as for disposal of fumigant wastes, treatment of fumigant-containing wastewater, and cleanup of fumigant residues in environmental media.

Allyl Compounds↗

PubMed2002

Study of alpha-crustacyanin utilizing halogenated canthaxanthins.

[structure: see text] The preparations and spectroscopic characteristics of five all-trans halogenated canthaxanthins are described in this letter. The air/light-sensitive halogenated canthaxanthins were used to study alpha-crustacyanin, a blue astaxanthin-protein complex, which is isolated from the carapace of the lobster. Steric and electronegative effects of the halogen substituents on the noncovalent interaction between astaxanthin and the protein in alpha-crustacyanin were observed.

Animals↗

PubMed2004

Effect of halogenation on edge-face aromatic interactions in a beta-hairpin peptide: enhanced affinity with iodo-substituents.

[reaction: see text] In a model beta-hairpin peptide, we have found that the favorable interaction of cross-strand aromatic rings can be enhanced by up to 1 kcal mol(-1) with halogen substituents. It appears that the polarizability of the halogen atoms accounts for the increase in stability and that there is a direct interaction between the N-terminal phenylalanine and the halogen atom. Thermal denaturation studies indicate that the interaction is enthalpically driven with an associated entropic cost. These findings have relevance to areas of molecular recognition and drug design.

Amino Acid Sequence↗

PubMed1996

Determination of halogens, with special reference to iodine, in geological and biological samples using pyrohydrolysis for preparation and inductively coupled plasma mass spectrometry and ion chromatography for measurement.

A method for determining iodine, bromine, chlorine and fluorine in geological and biological materials is described. In a quartz tube, solid material was heated to 1100 degrees C under a wet oxygen flow (pyrohydrolysis). By this process the halogens (I, Br, Cl, F) were separated from the matrix and then collected in a receiver solution. The chemical yield of iodine was determined by a radioactive tracer. ICP-MS and ion chromatographic measurements were used for the determination of the halogens. The method was optimized by investigating different experimental conditions. All four halogens can be trapped in the receiver solution from one combustion procedure. Precision and accuracy were evaluated by the analysis of environmental standard reference materials (rock, soil, milk, leaves, marine tissue). The concentrations in the materials analysed were in the ranges 0.006-50 mg kg-1 for I, 0.06-1300 mg kg-1 for Br, 50-1100 mg kg-1 for F and 400-11000 mg kg-1 for Cl. The lower values represent the practical detection limit of this method. The results obtained by the proposed method and the certified values are in good agreement.

Chromatography↗

PubMed1968

The utilization of some halogenated aromatic acids by Nocardia. Effects on growth and enzyme induction.

1. Halogen analogues of benzoate and p-nitrobenzoate did not support growth of Nocardia erythropolis. 2. These analogues, when present together with the parent compounds, inhibited growth of the organism. 3. The halogen analogues similarly inhibited oxidation of benzoate or p-nitrobenzoate by competent cells. 4. Fluoroacetate and 2-fluoro-4-nitrobenzoate caused comparable inhibition of growth on p-nitrobenzoate and both led to some citrate accumulation. 5. The induction of the p-nitrobenzoate-oxidation system was strongly inhibited by all the 2-halogeno-4-nitrobenzoates although the 2-fluoro and 2-chloro derivatives also acted as inducers. 6. Halogen analogues of benzoate also induced the benzoate-oxidation system.

Benzoates↗

PubMed2005

Orthodontic bracket shear bond strengths produced by two high-power light-emitting diode modes and halogen light.

The aim of this in vitro study was to compare the shear bond strength of orthodontic brackets cured with two different high-power light-emitting diode (LED) polymerization modes with traditional halogen polymerization. A total of forty-five extracted human premolar teeth were randomly divided into three groups. Each group consisted of 15 teeth mounted in an acrylic block. Following a standard enamel etching protocol, orthodontic brackets were cured on the first group of teeth with fast-mode LED, the second group with soft-start mode LED, and on the last group with a halogen light. After bonding, the shear bond strengths of the brackets were tested with a universal testing machine. The results showed that brackets cured with soft-start mode LED produced the highest shear bond strengths (23.86 +/- 6.20 MPa). No significant difference was found between fast-mode LED (17.14 +/- 5.75 MPa) and the halogen group (17.38 +/- 5.41 MPa) (P > .05). The LED is effective for bonding metal brackets to teeth, and the soft-start mode gives higher bond strengths than the fast mode.

Analysis of Variance↗

PubMed2003

QSPR-based prediction of adsorption of halogenated aromatics on yellow-brown soil.

Halogenated aromatic compounds exist widely in soil and aqueous environment. The study of their transport and distribution is quite important for pollution control and risk assessment. In the present work the adsorption coefficients of 28 halogenated benzenes, anilines and phenols on yellow-brown soil were measured with batch equilibrium method, and a prediction model was developed through the quantitative structure-property relationship (QSPR) technique. Then the obtained model was tested with Monte Carlo simulation and Jacknife methods. The results indicated that it was robust enough to estimate soil adsorption behaviors for the tested compounds. Based on the obtained model it could be deduced that the adsorption of halogenated aromatics on yellow-brown soil was not a simple partitioning process but involved complicated interactions.

Adsorption↗

PubMed2001

Synthesis of halogen-substituted 3-deazaadenosine and 3-deazaguanosine analogues as potential antitumor/antiviral agents.

Various 2-halogen-substituted analogues (38, 39, 43 and 44), 3-halogen-substituted analogues (51 and 52), and 2',3'-dihalogen-substituted analogues (57-60) of 3-deazaadenosine and 3-halogen-substituted analogues (61 and 62) of 3-deazaguanosine have been synthesized as potential anticancer and/or antiviral agents. Among these compounds, 3-deaza-3-bromoguanosine (62) showed significant cytotoxicity against L1210, P388, CCRF-CEM and B16F10 cell lines in vitro, producing IC50 values of 3, 7, 9 and 7 microM, respectively. Several 3-deazaadenosine analogues (38, 51, 57 and 59) showed moderate to weak activity against hepatitis B virus.

Animals↗

PubMed2002

A new method for determination of halogenated flame retardants in human milk using solid-phase extraction.

A method has been developed for quantitation of a selection of halogenated flame retardants in human milk. The method has been validated for seven polybrominated diphenyl ethers (PBDEs), BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, and BDE-183, and the halogenated phenols 2,4,6-tribromophenol (TriBP), pentabromophenol (PeBP), tetrachlorobisphenol-A (TCBP-A), and tetrabromobisphenol-A (TBBP-A). The sample preparation includes solid-phase extraction using an N-vinylpyrrolidone-divinylbenzene copolymer with on-column lipid decomposition followed by additional cleanup on sulfuric acid-silica columns and methylation of the phenolic compounds. Separation and detection were performed by gas chromatography-electron capture mass spectrometry, using a 5% phenyl 95% dimethylpolysiloxane column. The method has been validated in the range of 1.8-180 pg/g milk for most of the halogenated flame retardants. The average absolute recoveries were from 49 to 83%, and the average recoveries with respect to internal standards were in the range of 53 to 121%. Estimated limits of detection were in the range of 0.3 to 1.0 pg/g milk using a sample size of 5 g for all compounds, except TCBP-A, for which the limit of detection was estimated to 6.7 pg/g milk.

Female↗

PubMed1983

Effects of halogenated hydrocarbon anesthetics on responses to ligation of a coronary artery in chronically prepared rats.

Responses to ligation of the left anterior descending coronary artery (blood pressure, heart rate, ECG, arrhythmias, myocardial tissue loss, and mortality) were investigated in chronically prepared rats anesthetized with one of various halogenated hydrocarbon anesthetics. Halothane (inhaled concentrations of 0, 0.25, 0.5, 1.0, and 2.0%) reduced arrhythmias, mortality, and "S-T" segment changes in the ECG in a dose-related manner. The most effective antiarrhythmic concentrations were 0.5 and 1.0%. Other halogenated hydrocarbon anesthetics (chloroform, enflurane, isoflurane, methoxyflurane, and trichlorethylene) were investigated at minimal anesthetic concentrations. Of these, only chloroform and enflurane reduced arrhythmias. However, both increased mortality as a result of nonarrhythmic causes. At one-half anesthetic concentrations, chloroform (0.25%) and enflurane (0.75%) were not antiarrhythmic and mortality resulting from nonarrhythmic causes was not increased. In the chronically prepared rat, halothane at anesthetic and subanesthetic concentrations has antiarrhythmic actions against ligation-induced arrhythmias, reducing mortality. Of the other halogenated hydrocarbons tested, only enflurane and chloroform had antiarrhythmic actions, however, mortality was high with both agents because of accompanying cardiovascular depression.

Anesthesia↗

PubMed1994

Degradation of halogenated aliphatic compounds: the role of adaptation.

A limited number of halogenated aliphatic compounds can serve as a growth substrate for aerobic microorganisms. Such cultures have (specifically) developed a variety of enzyme systems to degrade these compounds. Dehalogenations are of critical importance. Various heavily chlorinated compounds are not easily biodegraded, although there are no obvious biochemical or thermodynamic reasons why microorganisms should not be able to grow with any halogenated compound. The very diversity of catabolic enzymes present in cultures that degrade halogenated aliphatics and the occurrence of molecular mechanisms for genetic adaptation serve as good starting points for the evolution of catabolic pathways for compounds that are currently still resistant to biodegradation.

Adaptation, Physiological↗

PubMed2005

Lethal photosensitization of oral pathogens via red-filtered halogen lamp.

UNLABELLED: OBJECTIVE OF INVESTIGATION: The ability of laser irradiation in the presence of photosensitizing agent to induce lethal effect on oral bacteria is well documented. We designed an in-vitro experiment to achieve phototoxic results on two common oral pathogens, using a high intensity, red filtered halogen lamp. Our goal was to determine the minimum duration of light exposure and drug dilution to achieve at least 50% reduction in bacteria counts. METHODS: Two common oral pathogens, Porphyromonas gingivalis and Prevotella intermedia were used in experiments. The source for light energy was a continuous working, high intensity, red filtered, halogen lamp (HL) with light transmitted through a flexible light guide over petri dishes containing live bacteria. Microorganisms were exposed to light for 5, 10 and 20 min. Methylene Blue (MB) in concentrations of 0.1, 0.075, 0.05, 0.025 and 0.01% was used as a photosensitizing agent. Light energy alone and MB alone was used as controls. RESULTS AND DISCUSSION: Optimum lethal photosensitization (50% or more bacteria killing) of oral pathogens was achieved using halogen light illumination for 5 min and longer with 0.05% MB or exposure to light for 20 min in the presence of 0.025 and 0.01% MB. Light exposure of 20 min in the absence of MB was not effective in killing bacteria. In the absence of light, MB at concentrations of 0.025 and 0.001% was not effective. Reduction of bacteria with the use of 0.05% MB alone was also insignificant. However, 0.075 and 0.1% MB, even in the absence of light was found to be bacteriocidal. CONCLUSIONS: Our in-vitro data indicate that we were able to achieve lethal photosensitization of two common oral pathogens with high intensity red filtered HL in the presence of diluted MB. In this era of increased incidence of antibiotic resistance, bacterial killing with laser or light energy in the presence of photosensitizing agent can prove to be a valuable treatment modality.

Filtration↗

PubMed1978

Bacterial dehalogenation of halogenated alkanes and fatty acids.

Sewage samples dehalogenated 1,9-dichloronane, 1-chloroheptane, and 6-bromohexanoate, but an organism able to use 1,9-dichlorononane as the sole carbon source could not be isolated from these samples. Resting cells of Pseudomonas sp. grown on n-undecane, but not cells grown on glycerol, dehalogenated 1,9-dichlorononane in the presence of chloramphenicol. Resting cells of five other n-undecane-utilizing bacteria cleaved the halogen from dichlorononane and 6-bromohexanoate, and four dehalogenated 1-chloroheptane; however, none of these organisms used 1,9-dichlorononane for growth. By contrast, four benzoate-utilizing bacteria removed bromine from 6-bromohexanoate but had little or no activity on the chlorinated hydrocarbons. Incubation of sewage with 1,9-dichlorononane increased its subsequent capacity to dehalogenate 1,9-dichlorononane and 6-bromohexanoate but not 1-chloroheptane. A soil isolate could dehalogenate several dichloralkanes, three halogenated heptanes, and halogen-containing fatty acids. An enzyme preparation from this bacterium released chloride from 1,9-dichlorononane.

Caproates↗

PubMed1981

Selective enrichment of Pseudomonas spp. defective in catabolism after exposure to halogenated substrates.

Significant selective enrichments of mutants defective in catabolic pathways can be achieved by exposure of pseudomonad cells to halogenated analogs of growth substrates. Between 3 and 95% of viable clones rescued from such enrichments have been defective in specific catabolic pathways. This has been demonstrated for eight different catabolic pathways for aromatic compounds in pseudomonads, in which the genes are located on plasmids or on the chromosome. The plasmid-encoded pathways studied include those for the catabolism of p-cymene (CYM), m- and p-xylenes (TOL), naphthalene (NAH), salicylate (SAL), and 4-methylphthalate (MOP), and the chromosome-encoded pathways include those for p-hydroxybenzoate, monohydric phenols, and p-anisate utilization. The recalcitrance of halogenated compounds may, in part, be explained by these observations, which introduce an as yet not widely recognized factor in assessment of biodegradability of halogenated compounds and their effects on the transformation of the natural substrates.

Benzene Derivatives↗

PubMed1996

Halogen lamp phototoxicity.

BACKGROUND: The radiation from quartz halogen light bulbs has been reported to cause erythema in humans and skin tumors in experimental animals. OBJECTIVE: The objective of this study was to determine the relative risk of injury to humans due to the radiation from these lamps. METHODS: We studied a 12-volt 50-watt quartz halogen lamp. We measured its ultraviolet output spectrum and the biological toxicity of its radiation by means of its pyrimidine dimer-inducing capability. RESULTS: At a 1-cm distance, the 254-nm light output of the lamp is 3 x 10(-7) W/cm2/nm. Solar radiation at this wavelength is undetectable on the earth's surface, i.e., less than 10(-12) W/cm2/nm. At 290 nm, the lamp output is approximately 3 x 10(-6) W/cm2/nm, 5,000 times greater than the summertime sun at 1 p.m. at sea level in Kuwait. The UVB and UVA output of the lamp is roughly similar to the solar output under these conditions. We also measured the pyrimidine dimer-forming potential of the lamps relative to the sun for the purpose of estimating the DNA toxicity of the lamps. At a 7-cm distance the lamp induces approximately 3.9 pyrimidine dimers/100,000 bp/min. This is approximately 4 times more rapid than that of the noontime summer sun in Michigan. CONCLUSIONS: We conclude that direct radiation from these lamps can cause damage to human skin, due to their UVC and UVB output. We estimate that the relative risk to keratinocyte DNA in human skin, in vivo, from exposure to the 50-watt halogen lamp at a distance of 7 cm is between 27 and 400% of the noontime summer sun in Michigan.

DNA↗

PubMed2005

Histology of the vitreoretinal interface after indocyanine green staining of the ILM, with illumination using a halogen and xenon light source.

PURPOSE: To assess the histology of the retinal surface after staining of the inner limiting membrane (ILM) with indocyanine green (ICG) followed by illumination with halogen or xenon light sources in human donor and porcine eyes. METHODS: Ten eyes of six human donors and six porcine eyes were used in the study. In human donor eyes, the postmortem time varied between 7 and 38 hours, and porcine eyes were evaluated 9 hours after death. In all eyes, the vitreous was removed, and a few drops of 0.5% ICG were poured over the trephined posterior pole and carefully washed out after a period of 1 minute, with balanced salt solution. Then the stained retina was illuminated for 3 minutes with different light sources: a halogen light source of 145-W power or a xenon light source of 50-W power. Adjacent, unstained retina of each eye served as a control to assess postmortem artifacts. In two human and two porcine eyes ICG was applied without illumination. Retinal specimens were evaluated by light and electron microscopy. RESULTS: In human eyes, severe disorganization of the innermost retina and ILM loss were observed after ICG application with subsequent illumination with the halogen light source. After illumination with the xenon light source, there was only slight vacuolization of the innermost retina, with mostly intact Muller cells. The ILM remained in situ in relation to the retinal surface. Intact cellular architecture was found in all specimens after ICG staining without subsequent illumination and control specimens of unstained retina. In porcine eyes, no impact attributable to the light source or ICG alone was noted in this experimental setting. CONCLUSIONS: These findings suggest that adverse effects of ICG at the retinal surface may depend on the light source used during vitrectomy and correlate with the emission spectrum of the different light sources. In addition, care should be taken when comparing results obtained in human eyes and porcine eyes.

Adolescent↗

PubMed1986

Neuropsychological symptoms among metal workers exposed to halogenated hydrocarbons.

A cross-sectional study was designed as a questionnaire investigation with the aim of mapping the load of symptoms, especially signs of neuropsychological dysfunction in relation to degreasing with halogenated hydrocarbons. The primary study group, 240 metal workers, comprised all identifiable persons engaged in degreasing with halogenated hydrocarbons in the county of Aarhus, the control group were 350 randomly selected semi-skilled metal workers. The final number of participants were 462 metal workers, corresponding to a rate of participation of 78.3%. The main findings were highly significant associations between exposure to halogenated hydrocarbons and symptoms of psychological dysfunction both at bivariate and multivariate analyses after adjustment for 4 potential confounder variables, age, alcohol consumption, neurological events and exposure to other organic solvents. Furthermore a dose-response-like relation could be demonstrated.

Adolescent↗