Interactions of highly and low virulent Mycoplasma hyopneumoniae isolates with the respiratory tract of pigs     

Meyns T  Maes D  Calus D  Ribbens S  Dewulf J  Chiers K  de Kruif A  Cox E  Decostere A  Haesebrouck F 《Veterinary microbiology》2007,120(1-2):87-95

Mycoplasma hyopneumoniae is the etiological agent of swine enzootic pneumonia, a chronic nonfatal disease affecting pigs of all ages. To obtain better insight in the mechanisms responsible for differences in virulence between highly and low virulent M. hyopneumoniae isolates, 23 caesarean-derived, colostrum-deprived piglets were randomly assigned to three groups. Groups 1 and 2 consisted of nine animals each, which were intratracheally inoculated at 1 week of age with a highly or a low virulent isolate of M. hyopneumoniae, respectively. The remaining five animals were inoculated with sterile culture medium. Animals were euthanized at 5, 10, 15 and 28 days post-inoculation (DPI). Animals inoculated with the highly virulent isolate had more neutrophils in BAL fluid at 10, 15 and 28DPI compared to the other groups. At 10 and 15DPI, animals in the highly virulent group had significantly higher concentrations of TNF-alpha in BAL fluid. IL-1beta concentration in this group was higher at 5 and 28DPI compared to the other groups. From 10DPI onwards, significantly higher titres of M. hyopneumoniae were detected in the BAL fluid of animals inoculated with the highly virulent isolate compared to animals inoculated with the low virulent isolate. Additionally, the in vitro generation time of the highly virulent M. hyopneumoniae isolate was significantly shorter than that of the low virulent isolate. The present study indicates that the difference in pathogenicity between the highly and low virulent isolates is associated with a faster in vitro growth, a higher capacity to multiply in the lungs and the induction of a more severe inflammation process by the highly virulent isolate.  相似文献   

Passive immunization to reduce Campylobacter jejuni colonization and transmission in broiler chickens     

David Hermans  Katleen Van Steendam  Elin Verbrugghe  Marc Verlinden  An Martel  Tomasz Seliwiorstow  Marc Heyndrickx  Freddy Haesebrouck  Lieven De Zutter  Dieter Deforce  Frank Pasmans 《Veterinary research》2014,45(1):27

Campylobacter jejuni is the most common cause of bacterium-mediated diarrheal disease in humans worldwide. Poultry products are considered the most important source of C. jejuni infections in humans but to date no effective strategy exists to eradicate this zoonotic pathogen from poultry production. Here, the potential use of passive immunization to reduce Campylobacter colonization in broiler chicks was examined. For this purpose, laying hens were immunized with either a whole-cell lysate or the hydrophobic protein fraction of C. jejuni and their eggs were collected. In vitro tests validated the induction of specific ImmunoglobulinY (IgY) against C. jejuni in the immunized hens’ egg yolks, in particular. In seeder experiments, preventive administration of hyperimmune egg yolk significantly (P < 0.01) reduced bacterial counts of seeder animals three days after oral inoculation with approximately 10⁴ cfu C. jejuni, compared with control birds. Moreover, transmission to non-seeder birds was dramatically reduced (hydrophobic protein fraction) or even completely prevented (whole-cell lysate). Purified IgY promoted bacterial binding to chicken intestinal mucus, suggesting enhanced mucosal clearance in vivo. Western blot analysis in combination with mass spectrometry after two-dimensional gel-electrophoresis revealed immunodominant antigens of C. jejuni that are involved in a variety of cell functions, including chemotaxis and adhesion. Some of these (AtpA, EF-Tu, GroEL and CtpA) are highly conserved proteins and could be promising targets for the development of subunit vaccines.  相似文献   

Topsoil characterization—recommendations for revision and expansion of the FAO‐Draft (1998) with emphasis on humus forms and biological features     

Gabriele Broll  Hans‐Jrg Brauckmann  Mark Overesch  Birte Junge  Claudia Erber  Gerhard Milbert  Denis Baize  Freddy Nachtergaele 《植物养料与土壤学杂志》2006,169(3):453-461

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Comparative study on physical and mechanical properties of laminated veneer lumber and plywood panels made of wood from fast-growing <Emphasis Type="Italic">Gmelina arborea</Emphasis> trees     

Carolina?Tenorio  Róger?MoyaEmail author  Freddy?Mu?oz 《Journal of Wood Science》2011,57(2):134-139

Laminated products, such as laminated veneer lumber (LVL) or plywood (PW), have become important recently. The objective of this study was to determine and compare properties of panels fabricated with veneers of Gmelina arborea trees in a fast-growth plantation and glued with phenol formaldehyde resin. The results showed that LVL and PW physical and mechanical properties are comparable to those of solid wood with a specify gravity of 0.60. Moreover, these panels can be cataloged into group 2 of PS 1–95 of the Voluntary Products Standard of the United States. The difference in physical properties was not statistically significant between LVL and PW panels, except for water absorption. Some mechanical properties, such as hardness and glue-line shear, modulus of rupture in perpendicular flexure, nail and screw withdrawal parallel, and perpendicular strength, were statistically different between LVL and PW. However, no differences were established for the modulus of elasticity, tensile strength parallel to the surface, or tensile strength perpendicular to the surface. The differences were attributed to the venners’ orientation in the panels studied.  相似文献   

Characterization of volatiles in unhopped wort     

De Schutter DP  Saison D  Delvaux F  Derdelinckx G  Rock JM  Neven H  Delvaux FR 《Journal of agricultural and food chemistry》2008,56(1):246-254

The volatile fraction of wort components was studied during boiling. Not less than 118 volatile compounds were identified when unhopped pilsner wort was boiled and samples of wort and condensed vapors were analyzed with headspace SPME-GC/MS, of which 54 were confirmed with reference compounds. The wort samples contained 61 identifiable compounds, while the vapor condensate yielded 108 different compounds. Almost 30 known compounds were found that have not been described before in unhopped pilsner wort. One previously unknown aldol reaction product was tentatively identified as 2-phenyl-2-octenal. The detection of branched 2-alkenals underlines the importance of the aldol condensation in Maillard-type reactions, while the tentative identification of alkyloxazoles and alkylthiazoles could once more accentuate the central role of alpha-dicarbonyl compounds, aldehydes, and amino acids in flavor generation. The condensation of wort vapors joined with the SPME-GC/MS technique has proven to be a useful tool in volatile analysis.  相似文献   

Early in vivo interactions of Actinobacillus pleuropneumoniae with tonsils of pigs.     

K Chiers  F Haesebrouck  I van Overbeke  G Charlier  R Ducatelle 《Veterinary microbiology》1999,68(3-4):301-306

Twenty gnotobiotic piglets were inoculated with 5 x 10(8) colony forming units of an Actinobacillus pleuropneumoniae biotype 1-serotype 9 strain onto their tonsils. Five other piglets (controls) were inoculated with phosphate-buffered saline solution. Pigs were euthanized at 30 min, 90 min, 180 min, 6 h, 9 h, 12 h or 24 h after inoculation. At necropsy, samples were taken from the tonsils for bacteriological, histological, immuno-histochemical and electron microscopical examination. A. pleuropneumoniae was isolated from tonsils of all the infected pigs, but not from tonsils of the control pigs. Early after inoculation bacteria were mainly associated with the stratified squamous epithelium and detached epithelial cells. Vacuolization and desquamation of the epithelium was observed and many transmigrating neutrophils were present. At later times after inoculation, bacteria were found closely associated with the crypt-walls and with detached cells present in the crypts. A strong neutrophil migration was observed mainly in the deeper parts of the crypts. It is concluded that attachment of A. pleuropneumoniae to tonsillar epithelial cells probably constitutes a first step in establishing bacteria at this body site.  相似文献   

IncK plasmid-mediated tetracycline resistance in Edwardsiella ictaluri isolates from diseased freshwater catfish in Vietnam     

Tu Thanh Dung  Freddy Haesebrouck  Patrick Sorgeloos  Nguyen Ahn Tuan  Frank Pasmans  Annemieke Smet  Annemie Decostere   《Aquaculture (Amsterdam, Netherlands)》2009,295(3-4):157-159

Eight tetracycline resistant Edwardsiella ictaluri isolates obtained from diseased freshwater catfish (Pangasianodon hypophthalmus) in Vietnam, and showing different resistance phenotypes to other antimicrobial agents, were studied. The tet genes were determined using PCR. Conjugation experiments were performed to assess transferability of the tetracycline resistance determinant and the size and incompatibility group (Inc) of each tet-carrying plasmid were determined. PCR and sequencing were used for characterization of the co-transferred resistance genes. A tetA gene was demonstrated in the E. ictaluri isolates and for all of them, Escherichia coli transconjugants were obtained. All transconjugants contained high-molecular weight tetA-carrying plasmids (~ 140 kb) belonging to the incK group, as was shown with the PCR-based replicon typing method. The strA–strB, dhfr1 and sul 2 genes were detected on the tetA-carrying plasmids of the transconjugants showing resistance to streptomycin, trimethoprim and sulfonamides, respectively. The dhfr1 gene was found to be located in a class 1 integron as determined by PCR and sequencing. Interestingly, the 3′ CS region of class 1 integrons was not detected by PCR. This study shows the presence of incK plasmid-mediated tetracycline resistance among E. ictaluri isolates from diseased freshwater catfish in Vietnam.  相似文献   

A typology of fisheries management tools: using experience to catalyse greater success          下载免费PDF全文

Elizabeth R Selig  Oren Ahoobim  Freddy Arocha  Annabelle Cruz‐Trinidad  Rod Fujita  Mafaniso Hara  Laure Katz  Patrick McConney  Blake D Ratner  Lina M Saavedra‐Díaz  Anne‐Maree Schwarz  Djiga Thiao  Elin Torell  Sebastian Troëng  Sebastian Villasante 《Fish and Fisheries》2017,18(3):543-570

Fisheries provide nutrition and livelihoods for coastal populations, but many fisheries are fully or over‐exploited and we lack an approach for analysing which factors affect management tool performance. We conducted a literature review of 390 studies to assess how fisheries characteristics affected management tool performance across both small‐scale and large‐scale fisheries. We defined success as increased or maintained abundance or biomass, reductions in fishing mortality or improvements in population status. Because the literature only covered a narrow set of biological factors, we also conducted an expert elicitation to create a typology of broader fishery characteristics, enabling conditions and design considerations that affect performance. The literature suggested that the most commonly used management tool in a region was often the most successful, although the scale of success varied. Management tools were more often deemed successful when used in combination, particularly pairings of tools that controlled fishing mortality or effort with spatial management. Examples of successful combinations were the use of catch limits with quotas and limited entry, and marine protected areas with effort restrictions. The most common factors associated with inadequate biological performance were ‘structural’ issues, including poor design or implementation. The expert‐derived typologies revealed strong local leadership, high community involvement and governance capacity as common factors of success across management tool categories (i.e. input, output and technical measures), but the degree of importance varied. Our results are designed to inform selection of appropriate management tools based on empirical data and experience to increase the likelihood of successful fisheries management.  相似文献