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At least 811 records · Page 45Linked to original sources
PubMed1995

[Epidemiology of microbial resistance to biocides].

In order to estimate the distribution of bacteria and fungi with an elevated level of resistance to antimicrobial substances, we have analyzed water samples and surveyed institutions presumably concerned with analyses of microbial resistance (university institutes for hygiene, health authorities) by means of questionnaire. A total of 41 water samples was drawn from various aquatic biotopes in the region of Heidelberg. The samples originated from the effluents of a community sewage treatment plant, from the Neckar river, from drinking water supplies and from public swimming pools. The following substance groups were included in a search for bacteria with an elevated resistance to antiseptics and disinfectants: Aldehydes, biguanides, quaternary ammonium compounds (QAC), phenols and halogen. Upon determination of the maximal tolerated concentrations to these antimicrobial agents, samples of treated wastewater effluents showed a considerably higher prevalence of bacteria resistant to formaldehyde, chlorhexidine and QAC. The highest levels of resistance were found in Pseudomonas aeruginosa, Pseudomonas putida, Pseudomonas fluorescens and Enterobacter species. The maximal tolerated level of 0.06 percent formaldehyde by weight was considerably higher than the levels tolerated by the corresponding ATCC reference strains. The highest levels of resistance to a biguanid/QAC preparation were seen in isolates of Alcaligenes species and Providencia species, with a maximal tolerated level of 0.5 volume percent. In addition, several isolates of E. coli and Klebsiella species were observed which showed a considerably higher level of resistance to the biguanide preparation as compared to the corresponding ATCC reference strains. A questionnaire was mailed to a series of institutions and companies presumably concerned with problems of microbial resistance. Responses were in accordance with our own observations, both with regard to the spectrum of bacteria observed and to the antimicrobial substances concerned.

Aldehydes↗
PubMed1995

Transport of organic environmental contaminants to animal products.

A large number of chemical contaminants potentially may be present in agricultural environments, leading to exposure of animals and potential residues in animal products. The contamination may be either widespread, as a result of aerial transport of industrial emissions, or localized, as a result of accidental emissions and spills, improper waste disposal, contaminants in useful products, and areas of past use of products now banned. The halogenated hydrocarbons, including the polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and persistent organochlorine insecticides remaining from past use, are the contaminants of most concern. Depending on the degree and pattern of chlorine substitution, these compounds are resistant to degradation and tend to accumulate in the fat of animals and their products. Other classes of environmental contaminants as exemplified by the PAHs, phthalate esters, acid phenolics, and nitrosamines also may occur widely in the environment. These compounds are unlikely to be transported to animal products because the compounds are water-soluble or can be metabolized to water-soluble products, which are excreted in the urine and thus do not bioaccumulate in products such as milk and meat. The points of entry of environmental contaminants into agricultural environments usually are plants and soils. Lipophilic compounds such as the halogenated hydrocarbons are not taken up and translocated by plants. Contamination of plants is mainly a surface phenomenon resulting from aerial deposition of emissions or deposition of compounds volatilized from the surface of contaminated soil. Thus, fibrous roughages used primarily in feeding cattle and other ruminants will be the most important pathway of animal exposure and transport to human foods. The second pathway of animal exposure is by ingestion of contaminated soil while grazing or when confined to unpaved facilities. As in the case of feed sources, cattle is the species most vulnerable to exposure by the soil ingestion pathway under most commercial management systems, but poultry and swine are more vulnerable in those infrequent situations in which these species have access to contaminated soil.

Animal Feed↗
PubMed2006

Non-target screening of extractable and non-extractable organic xenobiotics in riverine sediments of Ems and Mulde Rivers, Germany.

Subaquatic sediment samples derived form Elbe and Mulde Rivers, Germany, were analyzed for extractable and non-extractable anthropogenic organic compounds by a non-target screening approach. Applied methodologies were gas chromatography-mass spectrometry, dispersion extraction and degradation procedures, particularly alkaline and acidic hydrolysis, boron tribromide treatment, ruthenium tetroxide oxidation as well as pyrolysis and TMAH (tetramethylammonium hydroxide)-thermochemolysis. Numerous compounds were identified, including halogenated benzenes, anisoles, styrenes, alkanes, diphenylmethane derivates, anilines, phenols and diphenyl ethers. The results were interpreted with respect to compound specific modes of incorporation as well as to potential sources (e.g. municipal, agricultural, industrial). Extractable and non-extractable fractions differed significantly with respect to their qualitative and quantitative composition. For example, quantities in the extractable and non-extractable fractions of chlorinated benzenes differed up to factor 50. Among other significant results, the investigation revealed hints for a dependence of the mode of incorporation of chlorinated benzenes on their substitution pattern.

Agriculture↗
PubMed1975

[Antimicrobial action of potential isothiocyanate forming substances 7th communication (author's transl)].

A number of (N-aryl-dithiocarbamino)-alkanecarbonic acids bearing halogen substituents and related compounds are described which may be considered potential isothicyanate forming substances. The in vitro fungistatic activity of these compounds was investigated and the results obtained compared with those of captan and thiram. It was demonstrated that the halogen substituted (N-aryl)-dithiocarbamino)-alkanecarbonic acids exert an intensive fungistatic effect with a wide spectrum of activity and that the most active of them are equal to captan and thiram.

Antifungal Agents↗
PubMed2005

Improved prediction of octanol-water partition coefficients from liquid-solute water solubilities and molar volumes.

A volume-fraction-based solvent-water partition model for dilute solutes, in which the partition coefficient shows a dependence on solute molar volume (V), is adapted to predict the octanol-water partition coefficient (K(ow)) from the liquid or supercooled-liquid solute water solubility (Sw), or vice versa. The established correlation is tested for a wide range of industrial compounds and pesticides (e.g., halogenated aliphatic hydrocarbons, alkylbenzenes, halogenated benzenes, ethers, esters, PAHs, PCBs, organochlorines, organophosphates, carbamates, and amides-ureas-triazines), which comprise a total of 215 test compounds spanning about 10 orders of magnitude in Sw and 8.5 orders of magnitude in K(ow). Except for phenols and alcohols, which require special considerations of the K(ow) data, the correlation predicts the K(ow) within 0.1 log units for most compounds, much independent of the compound type or the magnitude in K(ow). With reliable Sw and V data for compounds of interest, the correlation provides an effective means for either predicting the unavailable log K(ow) values or verifying the reliability of the reported log K(ow) data.

Models, Theoretical↗
PubMed1989

[The mutagenicity of organic microcontaminants in the environment. IV. The mutagenicity of volatile organic halogens in the SOS-chromotest].

To determine the sensitivity and responsibility of microbial shortterm-tests for detection of the mutagenic potency of volatile halogenated hydrocarbons (OHC) 18 pure substances from the groups of halomethanes, -ethanes and ethylenes were examined with the SOS-Chromotest. The strain Escherichia coli PQ37 was used in the standard procedure (macro procedure) with and without metabolic activation by Aroclor 1254 induced rat-liver microsomes. Although the selected OHC were tested to high doses, none of the tested compounds showed mutagenic effects in Escherichia coli PQ37. Also those OHC's, which showed positive results in the Ames test or being suspected of carcinogenicity, showed no positive results in the SOS-Chromotest. Therefore, the standard procedure of SOS-Chromotest is not suitable to detect the mutagenicity of volatile organic and halogenated compounds. Supplementary investigations with modified methods are necessary to check the results, because there is a good correlation between Ames test and SOS-Chromotest by testing other groups of compounds.

Animals↗
PubMedDate not supplied

Synthesis and biological evaluation of halogenated naphthyridone carboxamides as potential ligands for in vivo imaging studies of substance P receptors.

With the aim of developing new radioligands for in vivo studies of substance P receptors using positron emission tomography or single photon emission computed tomography, 2- and 3-halo naphthyridone-6-carboxamide derivatives were synthesized. Their affinities toward the target receptors were evaluated on CHO cells and compared to the unsubstituted analogue EP 00652218 (IC(50) = 100 nM +/- 20). The IC(50) value was not altered in the case of 2-chloro compound 1 (IC(50) = 100 nM +/- 15) and only slightly reduced for the 2-fluoro and -iodo analogues 6 and 8 (IC(50) = 500 nM +/- 80). A drastic reduction in binding (IC(50) > 1000 nM) was observed for the halogenated compounds 2-5, 7, and 9.

Animals↗
PubMed2003

Application of silicon-based cross-coupling technology to triflates.

Aryl silatranes undergo fluoride-induced cross-coupling with aryl triflates to provide unsymmetrical biaryl derivatives in good to excellent yields. Silatranes also couple with aryl iodides and bromides, although the yields of adduct are lower than with the corresponding siloxane derivates. Aryl siloxanes (which had previously failed to couple with triflates) can be employed for triflate couplings using the Denmark modification, although the yields are lower than the corresponding silatrane reactions.

Biphenyl Compounds↗
PubMed2005

Reductive coupling of terpenic allylic halides catalyzed by Cp2TiCl: a short and efficient asymmetric synthesis of onocerane triterpenes.

[reaction: see text] Titanocene chloride catalyzes the regioselective alpha,alpha'-homocoupling of terpenic allylic halides. This process has been employed in the short and effective synthesis of terpenoids such as beta-onoceradiene (1), beta-onocerin (2), and squalene (3). Evidence is presented for eta1-allyltitanium species being involved in the coupling.

Allyl Compounds↗
PubMed2004

The synthesis and crystal structures of halogenated tolans p-X-C6H4-C[triple bond]C-C6F5 and p-X-C6F4-C[triple bond]C-C6H5(X=F, Cl, Br, I).

A series of halogenated, partially fluorinated tolans of general formula p-X-C6H4-C[triple bond]C-C6F5[X=I (1), Br (2), Cl (3), F (4)] and p-X-C6F4-C[triple bond]C-C6H5[X=I (5), Br (6)] have been prepared via palladium-catalysed Sonogashira cross-coupling, or for X=Cl (7), by nucleophilic aromatic substitution reactions. The single-crystal X-ray structures of 1-3 and 5-6 have been determined. The structures reveal that the molecular packing is characterized by either arene-perfluoroarene interactions (3), or halogen-halogen interactions (isomorphous 1 and 2), or neither (isomorphous 5 and 6). The structure of represents the first fully determined crystal structure of a compound that contains a halogen atom other than fluorine, in which arene-perfluoroarene interactions are present.

Journal Article↗
PubMed2001

Dehalogenation of dichloromethane by dichloromethane dehalogenase/glutathione S-transferase leads to formation of DNA adducts.

Formation of DNA adducts following conversion of dichloromethane by bacterial dichloromethane dehalogenase/glutathione S-transferase was demonstrated. Adducts included dichloromethane carbon and glutathione sulfur atoms. A reaction with DNA occurred preferentially at guanine bases. Increased DNA degradation in a polA mutant of Methylobacterium dichloromethanicum DM4 grown with dichloromethane confirmed the genotoxicity associated with dichloromethane degradation, suggesting an important role of DNA repair in the metabolism of halogenated, DNA-alkylating compounds by bacteria.

DNA Adducts↗