Slaughterhouse effluent discharges into rivers not responsible for environmental occurrence of enteroaggregative Escherichia coli     

Delphine Bibbal  Monique Kérourédan  Estelle Loukiadis  Flemming Scheutz  Eric Oswald  Hubert Brugère 《Veterinary microbiology》2014,168(2-4):451-454

Enteroaggregative Shiga-toxin-producing Escherichia coli strains were responsible for a massive outbreak in Europe in 2011, and had been previously isolated from French patients. The objective of this study was to investigate the presence of enteroaggregative E. coli (EAEC) in slaughterhouse effluents (wastewater, slurry, sludge and effluents), and in river waters near these slaughterhouses. A total of 10,618 E. coli isolates were screened by PCR for the presence of EAEC-associated genetic markers (aggR, aap and aatA). None of these markers was detected in E. coli isolated from slaughterhouse samples. A unique enteroaggregative E. coli (EAEC) O126:H8 was detected in river water sampled upstream from slaughterhouse effluent discharge. These results confirmed that animals might not be reservoirs of EAEC, and that further studies are required to evaluate the role of the environment in the transmission of EAEC to humans.  相似文献   

Elementary structural motifs in a random network of cytosine adsorbed on a gold(111) surface     

Otero R  Lukas M  Kelly RE  Xu W  Laegsgaard E  Stensgaard I  Kantorovich LN  Besenbacher F 《Science (New York, N.Y.)》2008,319(5861):312-315

Nonsymmetrical organic molecules adsorbed on solid surfaces may assemble into random networks, thereby providing model systems for organic glasses that can be directly observed by scanning tunneling microscopy (STM). We investigated the structure of a disordered cytosine network on a gold(111) surface created by thermal quenching, to temperatures below 150 K, of the two-dimensional fluid present on the surface at room temperature. Comparison of STM images to density functional theory calculations allowed us to identify three elementary structural motifs (zigzag filaments and five- and six-membered rings) that underlie the whole supramolecular random network. The identification of elementary structural motifs may provide a new framework for understanding medium-range order in amorphous and glassy systems.  相似文献   

Electron transfer-induced dynamics of oxygen molecules on the TiO2(110) surface     

Wahlström E  Vestergaard EK  Schaub R  Rønnau A  Vestergaard M  Laegsgaard E  Stensgaard I  Besenbacher F 《Science (New York, N.Y.)》2004,303(5657):511-513

Diffusion of oxygen molecules on transition metal oxide surfaces plays a vital role for the understanding of catalysis and photocatalysis on these materials. By means of time-resolved scanning tunneling microscopy, we provide evidence for a charge transfer-induced diffusion mechanism for O2 molecules adsorbed on a rutile TiO2(110) surface. The O2 hopping rate depended on the number of surface donors (oxygen vacancies), which determines the density of conduction band electrons. These results may have implications for the understanding of oxidation processes on metal oxides in general.  相似文献   

Identification of fish species after cooking by SDS-PAGE and urea IEF: a collaborative study     

Etienne M  Jérôme M  Fleurence J  Rehbein H  Kündiger R  Mendes R  Costa H  Pérez-Martín R  Piñeiro-González C  Craig A  Mackie I  Malmheden Yman I  Ferm M  Martínez I  Jessen F  Smelt A  Luten J 《Journal of agricultural and food chemistry》2000,48(7):2653-2658

A collaborative study, to validate the use of SDS-PAGE and urea IEF, for the identification of fish species after cooking has been performed by nine laboratories. By following optimized standard operation procedures, 10 commercially important species (Atlantic salmon, sea trout, rainbow trout, turbot, Alaska pollock, pollack, pink salmon, Arctic char, chum salmon, and New Zealand hake) had to be identified by comparison with 22 reference samples. Some differences in the recoveries of proteins from cooked fish flesh were noted between the urea and the SDS extraction procedures used. Generally, the urea extraction procedure appears to be less efficient than the SDS extraction for protein solubilization. Except for some species belonging to the Salmonidae family (Salmo, Oncorhynchus), both of the analytical techniques tested (urea IEF, SDS-PAGE) enabled identification of the species of the samples to be established. With urea IEF, two laboratories could not differentiate Salmo salar from Salmo trutta. The same difficulties were noted for differentiation between Oncorhynchus gorbuscha and Oncorhynchus keta samples. With SDS-PAGE, three laboratories had some difficulties in identifying the S. trutta samples. However, in the contrast with the previous technique, SDS-PAGE allows the characterization of most of the Oncorhynchus species tested. Only Oncorhynchus mykiss was not clearly recognized by one laboratory. Therefore, SDS-PAGE (Excel gel homogeneous 15%) appears to be better for the identification, after cooking, of fish such as the tuna and salmon species which are characterized by neutral and basic protein bands, and urea IEF (CleanGel) is better for the gadoid species, which are characterized by acid protein bands (parvalbumins). Nevertheless, in contentious cases it is preferable to use both analytical methods.  相似文献   

Analysis of acid-soluble glycogen in pork extracts of two PRKAG3 genotypes by 1H liquid-state NMR spectroscopy and biochemical methods     

Larsen FH  Essén-Gustavsson B  Jensen-Waern M  Lametsch R  Karlsson AH  Lindahl G 《Journal of agricultural and food chemistry》2011,59(22):11895-11902

Meat extracts with acid-soluble glycogen (macroglycogen) from M. longissmus dorsi of carriers and noncarriers of the PRKAG3 mutation (RN(-) and rn(+) genotype) were analyzed by both (1)H liquid-state NMR spectroscopy and a biochemical method. The (1)H NMR analysis revealed that shorter polymers (dimers, trimers, etc.) of α-1,4-linked glucose were generated 24-48 h post-mortem. This is not possible to elucidate with the biochemical method, by which only the total amount of hydrolyzed glucose residues is determined. The shorter polymers were primarily formed in carriers of the PRKAG3 mutation, suggesting different post-mortem glycogen degradation mechanisms in the two genotypes.  相似文献   

Rift Valley fever virus activity in East Africa in 1989.     

F G Davies  T M Logan  Y Binepal  P Jessen 《The Veterinary record》1992,130(12):247-249

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Oxygen-mediated diffusion of oxygen vacancies on the TiO2(110) surface     

Schaub R  Wahlström E  Rønnau A  Lagsgaard E  Stensgaard I  Besenbacher F 《Science (New York, N.Y.)》2003,299(5605):377-379

Defects such as oxygen vacancies play a crucial role in the surface properties of transition metal oxides. By means of time-resolved, high-resolution scanning tunneling microscopy, we unraveled an adsorbate-mediated diffusion mechanism of oxygen vacancies on rutile TiO2(110). Adsorbed oxygen molecules mediate vacancy diffusion through the loss of an oxygen atom to a vacancy and the sequential capture of an oxygen atom from a neighboring bridging oxygen row, leading to an anisotropic oxygen vacancy diffusion pathway perpendicular to the bridging oxygen rows.  相似文献   

Spectrofluorimetric assays for hydrolytic activity in germinating wheat     

Flemming Heltved   《Journal of Cereal Science》1984,2(3):179-185

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Mixed poly (ethylene glycol) and oligo (ethylene glycol) layers on gold as nonfouling surfaces created by backfilling     

Lokanathan AR  Zhang S  Regina VR  Cole MA  Ogaki R  Dong M  Besenbacher F  Meyer RL  Kingshott P 《Biointerphases》2011,6(4):180-188

Backfilling a self-assembled monolayer (SAM) of long poly (ethylene glycol) (PEG) with short PEG is a well-known strategy to improve its potential to resist fouling. Here it is shown, using x-ray photoelectron spectroscopy, contact angle, and atomic force microscopy, that backfilling PEG thiol with oligo (ethylene glycol) (OEG) terminated alkane thiol molecules results in underbrush formation. The authors also confirm the absence of phase separated arrangement, which is commonly observed with backfilling experiments involving SAMs of short chain alkane thiol with long chain alkane thiol. Furthermore, it was found that OEG addition caused less PEG desorption when compared to alkane thiol. The ability of surface to resist fouling was tested through serum adsorption and bacterial adhesion studies. The authors demonstrate that the mixed monolayer with PEG and OEG is better than PEG at resisting protein adsorption and bacterial adhesion, and conclude that backfilling PEG with OEG resulting in the underbrush formation enhances the ability of PEG to resist fouling.  相似文献   

Qualitative and quantitative risk assessment for human salmonellosis due to multi-resistant Salmonella Typhimurium DT104 from consumption of Danish dry-cured pork sausages     

Alban L  Olsen AM  Nielsen B  Sørensen R  Jessen B 《Preventive veterinary medicine》2002,52(3-4):251-265

Salmonella Typhimurium DT104 (DT104) is unwanted in products for human consumption due to its antibiotic resistance and ability to cause disease. We intended to set up an improved monitoring and management program to aid in deciding when to use pork contaminated with DT104 for production of sausages without jeopardizing consumer safety. We started by carrying out two assessments of the risk for human health associated with consumption of sausages produced by: (1) Danish pork from average slaughter days; (2) imported pork (IMP) with average prevalence of DT104. The assessments showed that, if Salmonella is present, it is usually in lower numbers (≤50 per 400 cm² surface). Additionally, during processing, the numbers will be reduced by at least 2 log-units. In Danish (DK) pork, DT104 constitutes 0.2–1.0% of the Salmonella isolates reported, while in imported pork (IMP), 18%. We estimated that out of one million, 25 g servings of DK dry-cured sausages, up to two DT104 bacteria could be found in each of 245 servings. Out of one million servings of 25 g IMP dry-cured sausages, up to two DT104 bacteria would occur in each of 19,260 servings.  相似文献