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991.
992.
P Nansen J Gr?nvold R J J?rgensen S A Henriksen J Foldager K Sejrsen 《Veterinary parasitology》1989,32(2-3):199-211
This paper describes clinically manifest infections occurring as early as June and early July in first-season grazing calves in Denmark during the period 1972-1987. Two severe outbreaks in 1976, included in our experiments, were studied in detail. Herbage infectivity was particularly high in grass tufts surrounding cow pats that were present in high numbers around the time of turnout. It is hypothesized that the preceding extremely dry summer followed by a hard winter had indirectly retarded degradation of dung pats and thereby favoured the overwintering of the larval populations in the dung reservoirs. In a third experiment, conducted in the same year, the epidemiological pattern was more normal; presumably due to artificial irrigation of the pasture during the drought. Early-season cases that were recorded in 1980 and 1987 could possibly be related to cold winters and/or very early turnout. The findings are discussed in the light of ecological factors responsible for the breakdown of cow pats. The clinical implications are seen in relation to current control methods. 相似文献
993.
994.
Youlia?Denisov Oded?Yarden Stanley?FreemanEmail author 《European journal of plant pathology / European Foundation for Plant Pathology》2005,112(3):293-297
The vascular wilt pathogen Fusarium oxysporum f. sp. melonis causes worldwide yield losses of muskmelon. In this study, we characterized a UV-induced non-pathogenic mutant (strain 4/4) of F. oxysporum f. sp. melonis, previously identified as a potential biological control agent. During comparative analysis of vegetative growth parameters using different carbon sources, mutant strain 4/4 showed a delay in development and secretion of extracellular enzymes, compared to the wild type strain. Amendments of the growth medium with yeast extract, adenine or hypoxanthine, but not guanine, complemented the growth defect of strain 4/4, as well as secretion and partial activity of cellulases and endopolygalacturonases, indicating that the strain is an adenine auxotroph. Incubation of strain 4/4 conidia in adenine solution, prior to inoculation of muskmelon plants, partially restored pathogenicity to the mutant strain. 相似文献
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An evaluation was made of a bioptic material (21,916 appendices recovered from 1965 to 1974), in order to disclose relationships of the incidence of Enterobius vermicularis and the origin of appendicitis. A separate evaluation was made of a set of appendectomies (10,619 cases--from 1961 to 1970) for the purpose of detecting changes in pin worm-infested appendices by means of histological methods (683 cases). E. vermicularis was found in 6.03% of appendices. Included in our histological examination was a search for granulomas and eosinophile infiltrations. The former occurred in 1.14% of pin worm-infested appendices, the later in 1.74% and in 0.19%, or 2.18% in pin worm non-infested appendices. The results indicated a statistically highly significant difference in the incidence of granulomas. The incidence of granulomas in the appendix was increased in the present of pin worms in the appendix, and seemed also to be responsible for further pathological changes in it. 相似文献
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1000.