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PubMed1995

Occupational exposure to polychlorinated dibenzo-p-dioxins and dibenzofurans in a magnesium production plant.

OBJECTIVES: The production of magnesium is a well known source of both aliphatic and aromatic chlorinated compounds, among others the polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). The aim of this study was to establish whether increased concentrations of PCDDs and PCDFs could be found in the blood of workers in a magnesium plant. METHODS: Blood plasma from 10 workers, employed at a magnesium plant for 10 to 36 years, and from a control group consisting of nine people who had no direct contact with the production were studied. Isomer specific analyses of PCDDs and PCDFs by means of high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) techniques were performed. RESULTS: A significant increase was found in the concentrations of some of the congeners, mainly PCDFs, in the workers compared with the control group. Octachlorodibenzofuran (OCDF) is the congener that most strongly correlates with occupational exposure in the magnesium plant. Low concentrations of 1,2,3,4,6,8,9-heptachlorodibenzofuran were found in seven of the workers. Such isomers--that is, not 2,3,7,8-substituted--are rarely found in human samples. CONCLUSION: Due to the long biological half lives and lipid solubility of PCDDs and PCDFs, blood analyses may serve as an index of past cumulative occupational exposure and a means of assessing a person's exposure situation.

Benzofurans↗
PubMed2003

Phylogenetic analysis of bacterial populations in an anaerobic microbial consortium capable of degrading saturation concentrations of tetrachloroethylene.

An anaerobic microbial consortium able to biodegrade saturation levels of perchloroethylene (PCE) in a column containing a source zone of PCE was examined phylogenetically to determine microbial community structure and spatial variation in relation to the PCE source. The consortium was comprised of at least 34 members with 7 organisms sharing affiliations with known respiratory or cometabolic dechlorinators. Seven other organisms had their closest phylogenetic relative detected in other environments containing chlorinated compounds. Based on denaturing gradient gel electrophoresis, significant Bacteria were Dehalococcoides ethenogenes, Shewanella putrefaciens, and an Acetobacterium species. Spatial variations in community structure of the consortium relative to the PCE source zone were observed. A Pseudomonas species was predominant in a zone 30 cm from the PCE source. A Methanothrix species was predominant at points over 85 cm from the source zone. A Trichlorobacter species was detected where PCE concentrations were highest, up to 85 cm from the PCE source, whereas D. ethenogenes was ubiquitous to over 128 cm from the PCE source.

Anaerobiosis↗
PubMed1994

A polymeric drug delivery system for the simultaneous delivery of drugs activatable by enzymes and/or light.

Three water soluble copolymers based on N-(2-hydroxypropyl)methacrylamide were prepared. Copolymer I contains adriamycin, a chemotherapeutic agent, attached via enzymatically degradable oligopeptide (glycylphenylalanylleucylglycine; G-F-L-G) side chains. The other two copolymers contained the photosensitizer, meso-chlorin e6 monoethylene diamine disodium salt (Mce6). In Copolymer II, the chlorin is attached via the degradable G-F-L-G sequence, and it was bound by the nondegradable glycyl spacer in Copolymer III. Initially, the copolymers were characterized separately in vitro and in vivo. Combinations of the copolymer bound chemotherapeutic agent and each of the copolymer bound photosensitizers were then assessed for antitumor effect in vivo. Localization/retention studies (A/J mice; Neuro 2A neuroblastoma solid tumor) were performed with the two copolymers containing Mce6 as well as the free drug. Results of these experiments demonstrated a very different tumor uptake profile for the two copolymers. While the free drug was rapidly cleared from tumor tissue, the copolymer containing Mce6 attached via the non-degradable bond was retained for an extended period; drug concentrations in the tumor were high even after 5 days. On the other hand, a high concentration of the copolymer containing Mce6 bound via the degradable sequence was taken up by the tumor, yet its concentration in the tumor was substantially diminished at 48 h after administration. This shows indirect evidence of in vivo cleavage of Mce6 from the copolymer in the lysosomal compartment which is supported by direct evidence of cleavage by cathepsin B (a lysosomal enzyme) in vitro. Antitumor effects were assessed on Neuro 2A neuroblastoma induced in A/J mice for all three copolymers. Photodynamic therapy (PDT) proved the copolymer with Mce6 bound via the degradable oligopeptide sequence to be a more effective photosensitizer in vivo than the other chlorin containing copolymer. The difference in activity was consistent with the results obtained by photophysical analyses in which the free drug had a higher quantum yield of singlet oxygen generation than the polymer bound drug in buffer. The quantum yield of singlet oxygen generation increased with the enzymatic cleavage of the chlorin from the copolymer. Conditions were subsequently determined for which chemotherapy or PDT would show some antitumor effect, yet be incapable of curing tumors. Finally, combination therapy experiments were performed in which the copolymer bound adriamycin was mixed with either of the copolymer bound chlorin compounds and injected intravenously (i.v.) into the tail veins of mice.(ABSTRACT TRUNCATED AT 400 WORDS)

Acrylamides↗
PubMed1997

Defective neutrophil function in workers occupationally exposed to hexachlorobenzene.

In this work we have studied the respiratory burst and chemotaxis of polymorphonuclear leukocytes from 51 workers exposed to chlorinated compounds, which were compared with those of non-exposed, age- and sex-matched individuals. These two neutrophil functions were significantly reduced as compared to controls. No correlation was observed between the length of exposure, hexachlorobenzene (HCB) blood concentrations and neutrophil chemotaxis or the extent of nitroblue tetrazolium reduction.

Adult↗
PubMed2003

Decomposition of ethylene, a flower-senescence hormone, with electrolyzed anode water.

Electrolyzed anode water (EAW) markedly extended the vase life of cut carnation flowers. Therefore, a flower-senescence hormone involving ethylene decomposition by EAW with potassium chloride as an electrolyte was investigated. Ethylene was added externally to EAW, and the reaction between ethylen and the available chlorine in EAW was examined. EAW had a low pH value (2.5), a high concentration of dissolved oxygen, and extremely high redox potential (19.2 mg/l and 1323 mV, respectively) when available chlorine was at a concentration of about 620 microns. The addition of ethylene to EAW led to ethylene decomposition, and an equimolar amount of ethylene chlorohydrine with available chlorine was produced. The ethylene chlorohydrine production was greatly affected by the pH value (pH 2.5, 5.0 and 10.0 were tested), and was faster in an acidic solution. Ethylene chlorohydrine was not produced after ethylene had been added to EAW at pH 2.6 when available chlorine was absent, but was produced after potassium hypochlorite had been added to such EAW. The effect of the pH value of EAW on the vase life of cut carnations was compatible with the decomposition rate of ethylene in EAW of the same pH value. These results suggest that the effect of EAW on the vase life of cut carnations was due to the decomposition of ethylene to ethylene chlorohydrine by chlorine from chlorine compounds.

Electrolysis↗
PubMed1979

Thermal pollution consequences of the implementation of the president's energy message on increased coal utilization.

The thermal consequences of coal utilization are most meaningfully assessed in comparison with the form of power generation replaced by coal which is most likely nuclear. The different effects are influenced by siting decisions and the intrinsic thermal efficiencies of the two fuel systems. Nuclear power plants discharge 50% more waste Rheat to the atmosphere through cooling towers or to a water body than coal-fired plants. Coal-fired plants require about 2/3 as much water as nuclear power plants. Nearly every property of water is affected nonlinearly by temperature, and biological effects may amplify these changes because protein denaturation takes place more rapidly above 30 degrees C and these high temperatures affect bactericidal and viricidal activity of chlorine compounds. Usually algal populations change from a dominance of diatoms and green algae to dominance by blue-green algae. All organisms experience elevated metabolic rates at higher temperatures which may affect total energy needs, foraging ability, reproduction, migration and susceptibility to disease. Intake structures inevitably draw many organisms into the cooling system of a power plant, but the number and kind are influenced by its location, configuration, and mode of operation. Use of water recirculation systems reduces water use and with it, the number of organisms entrained. Mechanical damage in the cooling system to small organisms is generally low, but fish and their larvae and eggs may be seriously damaged. Discharge effects may also be severe but are generally local. The near field, where there are strong shear velocities and rapid temperature changes are particularly stressful to fish, and stringent limitations on the timing and strength of discharges may be required to reduce these stresses to nondamaging levels. Off-stream cooling systems may increase cloudiness, ground fog, precipitation, temperature and local winds, but these effects generally extend no further than 1000 m even in winter. There is considerable potential for using condenser cooling water for agricultural and aquacultural purposes such as irrigation, frost protection, undersoil heating, greenhouse heating and climate control. However, over the next few decades little of this waste heat is likely to be used creatively. The thermal consequences of implementing NEP are locally serious but do not pose regional problems. Creative use of the waste heat for aquaculture, agriculture, cogeneration, and power for energy intensive industries can be a powerful means of mitigating undesirable effects.

Animals↗
PubMed1983

The metabolism of tryptophan and 7-chlorotryptophan in Pseudomonas pyrrocinia and Pseudomonas aureofaciens.

Pseudomonas pyrrocinia ATCC 15958 and a mutant strain (ACN) of Pseudomonas aureofaciens ATCC 15926 possess a mechanism for the degradation of the tryptophan side chain. Indole, indole-3-carboxylic acid, indole-3-acetic acid and the corresponding compounds chlorinated or brominated at position 7, as well as indole-3-pyruvate and 7-chloroindole-3-pyruvate, were isolated from bacterial cultures. The chlorinated indole derivatives were isolated after the addition of 7-chloro-DL-tryptophan to cultures of P. pyrrocinia whereas their bromo analogues were found in the culture medium of the mutant strain ACN of P. aureofaciens, grown in the presence of sodium bromide. Enzymatic studies show that tryptophan is transaminated to indole-3-pyruvate, which is transformed to indole-3-acetaldehyde. Dehydrogenation of indole-3-acetaldehyde leads to indole-3-acetic acid, which is further metabolized to indole-3-carboxaldehyde, and converted by dehydrogenation to indole-3-carboxylic acid. Indole is formed by the spontaneous decarboxylation of indole-3-carboxylic acid.

Amino Acid Isomerases↗
PubMedDate not supplied

Composition of lipophylic extracts from two Tinicates, Styela sp. and Phallusia sp. from the Eastern Mediterranean.

Sterols, volatiles and lipids were isolated and identified from lipophylic extracts from two tunicates, Styela sp. and Phallusia sp., occurring in the Eastern Mediterranean. Seventeen sterols were identified. The sterol composition of the two organisms appeared to be similar except for the concentrations of 5alpha-stanols. Both tunicates were characterized by the presence of sterols with a (22Z)-double bond. In the volatiles significant amounts of chlorinated compounds were found (phenols in Styela sp. and hydrocarbons in Phallusia sp.). The fatty acid composition of triacylglycerols and phospholipids of the two tunicates showed significant differences.

Animals↗
PubMed2005

Geochemical modeling of gold precipitation conditions in the Bloco do Butiá Mine, Lavras do Sul/Brazil.

A geochemical modeling of gold deposition was performed using the EQ3/EQ6 software package using conditions inferred from geological, petrographic, geochemical and fluid inclusion data from the Bloco do Butiá gold mine, Lavras do Sul, RS. Gold in the mine occurs only in the pyrite structure (invisible gold). The pyrite occurs associated with white mica (phengite) in the zone of phyllic alteration. The process of gold deposition showed to be related to temperature and pH decrease. The pH decrease was fundamental to gold deposition by destabilization of sulfur species [Au(HS)2- , HAu(HS)2(0) and Au(HS)0] dissolved in the aqueous solution, being Au(HS)0 the main gold transporting complex. The addition of KCl is hard to accept as cause of gold precipitation because no Cl- was detected in phengite. However, the geochemical mass balance calculation resulted in the gain of some potassium in the zone of phyllic alteration. The precipitation of pyrite (+/- auriferous) may have been strongly influenced by iron availability resulting from dissolution of ferrous chlorites by the fluids responsible for phengite deposition. The low salinity in quartz grain fluid inclusions from the propylitized wall rock also indicates the little importance of chlorine as gold transporting agent. Sulfur, and not chlorine, compounds must have dominated the gold transporting complexes in the Bloco do Butiá gold area.

Journal Article↗
PubMedDate not supplied

Spatial distribution of DDT in sediments from estuarine rivers of central Florida.

Sediments may act as both a carrier for and a potential source of contaminants such as toxic organics in aquatic environments. This study investigated the spatial distribution of the pesticide DDT [1,1, 1-trichloro-2,2-bis(p-chlorophenyl)ethane] in sediments from the Cedar and Ortega Rivers located in the lower St. Johns River basin, Florida, USA, using field measurements and three-dimensional kriging analysis. High DDT concentrations were found near the junction of the Cedar and Ortega Rivers and at the north end of the Ortega River in the upper 0.5 m of the sediments, indicating that the sediment was enriched with DDT in the top layer although use of this chlorinated compound was banned in 1972. Further study revealed that the influence of sediment grain size or texture on DDT contamination was negligible in this river system and no linear correlations existed among DDT and its metabolites such as DDD [1,1-dichloro-2,2-bis(p-chlorophenyl)ethane] and DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene]. Comparison of three-dimensional distribution of DDT content to the Florida sediment quality assessment guideline or probable effect level (PEL) showed several "hot spots" in the Ortega River sediments, where DDT contents exceeded the PEL value of 4.78 microg kg(-1). Such contamination may pose a significant hazard to aquatic life.

DDT↗
PubMed1993

Nimesulide as a downregulator of the activity of the neutrophil myeloperoxidase pathway. Focus on the histoprotective potential of the drug during inflammatory processes.

Neutrophils, recruited to tissue sites of inflammation, release a variety of oxidants and enzymes, which are responsible for tissue damage. Among the oxidants released are potent chlorinated compounds, such as hypochlorous acid and chloramines, which induce tissue cell damage and inactivate protease inhibitors, particularly alpha 1-antitrypsin, the specific inhibitor of neutrophil elastase. In studying a rational approach to the pharmacological control of neutrophil-mediated tissue injury, we investigated the activity of the anti-inflammatory drug nimesulide. This agent reduced the function of the myeloperoxidase pathway (which generates hypochlorous acid), by exerting a cell-directed inhibitory activity, as shown by measurement of superoxide anion and hydrogen peroxide production. Nimesulide also inactivated hypochlorous acid directly and protected alpha 1-antitrypsin from the neutrophil-mediated oxidation. Thus, neutrophil elastolytic activity may be attenuated by nimesulide-spared alpha 1-antitrypsin. The prevention of oxidative inactivation of alpha 1-antitrypsin by nimesulide strictly correlates with the drug's ability to suppress the extracellular availability of hypochlorous acid. Taken together, these data suggest that nimesulide may prevent tissue injury at sites of inflammation by maintaining natural host protective systems.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2006

Novel anti-bacterials against MRSA: synthesis of focussed combinatorial libraries of tri-substituted 2(5H)-furanones.

Mucobromic and mucochloric acid were used as building blocks for the construction of a chemical combinatorial library of 3,4,5-trisubstituted 2(5H)-furanones. With these 2 butenolide building blocks, and eight alcohols a sublibrary of 16 dihalogenated 5-alkoxy-2(5H)-furanones was prepared. This sublibrary of 5-alkoxylated furanones was reacted with 16 amines generating a full size focussed combinatorial library of 256 individual compounds. This three dimensional combinatorial library of 3-halogen-4-amino-5-alkoxy-2(5H)-furanones was prepared around the benzimida-zolyl furanone lead structure by applying a solution phase combinatorial chemistry concept. Typical representatives of the library were purified and fully characterized and one x-ray structures was recorded, additionally. The 3-bromo-4-benzimizazolyl-5-methoxy-2(5H)furanone, Br-A-l, showed an MIC of 8 microg/ml against the multiresistant Staphylococcus aureus (MRSA).

Anti-Bacterial Agents↗
PubMed1998

Polymorphonuclear phagocytosis and killing in workers occupationally exposed to hexachlorobenzene.

Phagocytosis and intracellular killing of Candida albicans and Candida pseudotropicalis by neutrophils from 66 workers exposed to chlorinated compounds were studied. Phagocytosis with both antigens was normal in all the workers studied. However, lytic activity of the neutrophils in the presence of both antigens, C. albicans and C. pseudotropicalis was impaired. These findings might be related to a derangement in the antioxidant mechanisms and to some interference with GSH levels that might lead to the abnormal functions observed in neutrophils.

Adult↗
PubMed1989

Leukocytic oxygen activation and microbicidal oxidative toxins.

Following a brief introduction of cellular response to stimulation comprising leukocyte activation, three major areas are discussed: (1) the neutrophil oxidase; (2) myeloperoxidase (MPO)-dependent oxidative microbicidal reactions; and (3) MPO-independent oxidative reactions. Topics included in section (A) are current views on the activation mechanism, redox composition, structural and topographic organization of the oxidase, and its respiratory products. In section (B), emphasis is placed on recent research on cidal mechanisms of HOCl, including the oxidative biochemistry of active chlorine compounds, identification of sites of lesions in bacteria, and attendant metabolic consequences. In section (C), we review the (bio)chemistry of H2O2 and .OH microbicidal reactions, with particular attention being given to addressing the controversial issue of probe methods to identify .OH radical and critical assessment of the recent proposal that MPO-independent killing arises from site-specific metal-catalyzed Fenton-type chemistry.

Blood Bactericidal Activity↗
PubMed2006

Microbial diversity and bioremediation of a hydrocarbon-contaminated aquifer (Vega Baja, Puerto Rico).

Hydrocarbon contamination of groundwater resources has become a major environmental and human health concern in many parts of the world. Our objectives were to employ both culture and culture-independent techniques to characterize the dynamics of microbial community structure within a fluidized bed reactor used to bioremediate a diesel-contaminated groundwater in a tropical environment. Under normal operating conditions, 97 to 99% of total hydrocarbons were removed with only 14 min hydraulic retention time. Over 25 different cultures were isolated from the treatment unit (96% which utilized diesel constituents as sole carbon source). Approximately 20% of the isolates were also capable of complete denitrification to nitrogen gas. Sequence analysis of 16S rDNA demonstrated ample diversity with most belonging to the infinity, beta and gamma subdivision of the Proteobacteria, Bacilli, and Actinobacteria groups. Moreover, the genetic constitution of the microbial community was examined at multiple time points with a Functional Gene Array (FGA) containing over 12,000 probes for genes involved in organic degradation and major biogeochemical cycles. Total community DNA was extracted and amplified using an isothermal phi29 polymerase-based technique, labeled with Cy5 dye, and hybridized to the arrays in 50% formimide overnight at 50 degrees C. Cluster analysis revealed comparable profiles over the course of treatment suggesting the early selection of a very stable microbial community. A total of 270 genes for organic contaminant degradation (including naphthalene, toluene [aerobic and anaerobic], octane, biphenyl, pyrene, xylene, phenanthrene, and benzene); and 333 genes involved in metabolic activities (nitrite and nitrous oxide reductases [nirS, nirK, and nosZ], dissimilatory sulfite reductases [dsrAB], potential metal reducing C-type cytochromes, and methane monooxygenase [pmoA]) were repeatedly detected. Genes for degradation of MTBE, nitroaromatics and chlorinated compounds were also present, indicating a broad catabolic potential of the treatment unit. FGA's demonstrated the early establishment of a diverse community with concurrent aerobic and anaerobic processes contributing to the bioremediation process.

Bacteria↗
PubMed1976

[Evaluation of mirex for the control of pharaoh's ants].

The paper analyses the mode of action of the organic chlorine compound Mirex in laboratory colonies of the pharaoh's ant Monomorium pharaonis under the special view of practical use in control measures in comparison with the related insecticide Chlordecone (Kepone). Similar to Chlordecone the queens are very susceptible towards the action of Mirex. According to the regression lines of the mortality the best concentrations for practical control measures are in the range of 0.1 to 1%, respectively. Under laboratory conditions a reliable eradication is effected by an application of 0.001% Mirex over a period of three weeks. Such a treatment lead to the loss of reproductive capacity of the remaining living queens. These queens do not recover after transmission to normal colonies. The larvae were influenced in the same manner as the adults. At the recommended level of Mirex all of the larvae disappear within the first five days of application of the poison bait. Also a short termed use lead to a long lasting damage of the ant societies. Between different baits no significant difference could be demonstrated even when one bait obviously was better accepted than another. Because of the strong effect on intact colonies Mirex should be recommended for the control of this ant pest.

Animals↗
PubMed1999

C(6)F(5)XeCl and

Xenon(II) chlorine compounds can be obtained as the isolable organo derivatives C(6)F(5)XeCl and [(C(6)F(5)Xe)(2)Cl][AsF(6)] (whose cation is depicted) in 85 and 91 % yield, respectively. These compounds decompose vigorously at 36 degrees C and 100 degrees C, respectively, leading to the formation of C(6)F(5)Cl and Xe gas and of C(6)F(5)Cl, C(6)F(6), and [C(6)F(5)Xe][AsF(6)], respectively.

Journal Article↗