Transmission of encephalomyocarditis virus (EMCV) among pigs experimentally quantified   总被引：6，自引：0，他引：6  

Maurice H  Nielen M  Stegeman JA  Vanderhallen H  Koenen F 《Veterinary microbiology》2002,88(4):301-314

Two types of transmission experiments were performed to estimate the basic reproduction ratio R(0), indicating the level of encephalomyocarditis virus (EMCV) transmission among pigs. In a first experimental set-up with nine separate pairs, one randomly chosen piglet per pair was inoculated with a Belgian (myocardial) EMCV strain (B279/95, 10(3)TCID(50)/ml oronasally) and placed back into the pen. In the second experiment with two separate groups of five piglets, two piglets in each group were inoculated at the start. During the experiments, viraemia in blood and excretions was measured as well as the serological response against EMCV antigen. After death or euthanasia, the piglets were checked for heart lesions and virus isolation was done on various tissues. In both the experiments, the majority of the inoculated piglets either died with typical heart lesions (five out of nine and three out of four resp.), or produced high levels of neutralising antibody. EMC virus was isolated from the hearts of all piglets that died during either one of the experiments. The pairwise experiment revealed a point estimate for R(0) of 2.0 (95% confidence interval (CI)=0.37-10.74), while the group experiment resulted in a R(0)-value of 0.71 (95% CI=0.08-4.93). Combining the information from both experiments results in an estimate for R(0) of 1.24 (95% CI=0.39-4.35). Since R(0) has values around the threshold value of 1, the spread of EMCV due to contacts between pigs will in most cases be limited, but due to chance processes may lead to large outbreaks as well.  相似文献   

Identification of the Beet Cyst Nematode Heterodera schachtii by PCR     

Saïd Amiri  Sergei A. Subbotin  Maurice Moens 《European journal of plant pathology / European Foundation for Plant Pathology》2002,108(6):497-506

PCR-RFLPs of ITS-rDNA and PCR with species-specific primers were developed for identification of cysts and juveniles of the beet cyst nematode Heterodera schachtii. Restrictions of PCR product by MvaI or ScrFI distinguish H. schachtii, H. betae, H. trifolii and H. medicaginis. RFLP profiles with eight restriction enzymes for these four nematode species are presented. Based on Internal Transcribed Spacer sequences of populations from several Schachtii group species, a specific primer for H. schachtii was designed, permitting amplification of the target sequence from juveniles and cysts of the beet cyst nematode. A duplex PCR protocol tested with a wide range of nematode samples is described.  相似文献   

Multivariate structure-property relationships (MSPR) of pesticides     

Daniel Domine  James Devillers  Maurice Chastrette  Walter Karcher 《Pest management science》1992,35(1):73-82

Vapour pressures, aqueous solubilities, n-octanol/water partition coefficients, molecular weights, and Henry's law constants for 64 pesticides were obtained from the literature and analysed by means of Principal Component Analysis (PCA). Classical PCA displays underline structure-property relationships. However, interpretation of PCA requires reference to the original data matrix and comparisons made between every point. To overcome this problem, a novel graphical approach, based on collections of maps encoding the chemical and structural information included in the original data set, was used to interpret the results. Multivariate analyses coupled to graphical tools were useful for interpreting physicochemical properties of pesticides in terms of multivariate structure-property relationships (MSPR).  相似文献   

Characteristics of porcine circovirus-2 replication in lymphoid organs of pigs inoculated in late gestation or postnatally and possible relation to clinical and pathological outcome of infection.     

Romeo E Sanchez  Peter Meerts  Hans J Nauwynck  John A Ellis  Maurice B Pensaert 《Journal of veterinary diagnostic investigation》2004,16(3):175-185

In this study, the characteristics of porcine circovirus-2 (PCV2) replication (infectious virus titrations, distribution, and immunophenotyping of infected cells) in lymphoid organs were examined and related to the development of clinical signs and histological lesions in 26 piglets that had been inoculated with PCV2 either in utero or at 1 day of age. Piglets inoculated in utero at 92 or 104 gestational days (n = 12) were collected by Caesarean section at term and either sacrificed immediately or kept in isolators and allowed to live postnatally until 35 days postinoculation (PI). Caesarean-derived piglets inoculated at 1 day of age (n = 14) were sacrificed at 10, 21, 35, 42, and 49 days PI. Spleen and lymph nodes were collected for virologic and histopathological examinations. Clinical signs were not observed in any of the piglets. High virus titers (10(4.5-5.7) TCID50/g [TCID refers to tissue culture infectious dose]) were detected in 6 of the 26 piglets. Three of these 6 piglets were euthanized at 10 days PI, and infected cells of the monocyte-macrophage lineage (SWC3+, CD14+, and sialoadhesin [Sa]+ cells) and infected cells bearing lymphocyte markers (CD4+, CD8+, and immunoglobulin M+ cells) were identified by double-immunofluorescence labeling on serial cryostat sections. The other 3 piglets were euthanized at 21 and 35 days PI, and the majority of infected cells were SWC3+, CD14+, and Sa-. The absence of Sa in these infected cells, together with their localization in lymphocyte-dependent regions, suggests that they were infiltrating monocytic cells. Sialoadhesin is highly expressed in differentiated macrophages and not in peripheral blood mononuclear cells. In all 6 piglets with high virus titers, lymphocyte depletion and infiltration of monocytic cells were observed. In the remaining 20 piglets with virus titers less than 10(4.5) TCID50/g, the majority of infected cells were SWC3+, CD14+, and Sa+. In conclusion, it can be stated that high PCV2 titers in lymphoid organs may lead to the development of histological lesions similar to those observed in pigs with postweaning multisystemic wasting syndrome without causing disease. Furthermore, in lymphoid organs with high virus titers, infection occurs mainly in infiltrating monocytic cells and to a limited extent in cells bearing lymphocyte markers.  相似文献   

Sexual difference in ascorbic acid synthesis, tissue ascorbic acid and plasma total antioxidant capacity in mature chickens     

Maurice DV  Lightsey SF 《British poultry science》2007,48(4):519-523

1. An experiment was conducted with commercial White Leghorn type chickens to determine the effect of gender on tissue ascorbic acid concentration, antioxidant capacity and ascorbic acid synthesis. 2. Birds reared and maintained on litter were given a standard layer diet, without supplemental ascorbic acid, from 18 weeks of age. Tissue ascorbic acid concentration, plasma total antioxidant capacity and renal L-gulonolactone oxidase activity were measured at 30 weeks of age. 3. Females and males differed in ascorbic acid synthesis, as measured by renal L-gulonolactone oxidase activity, and tissue ascorbic acid concentration. 4. Plasma total antioxidant capacity and adrenal, gonadal, plasma and pituitary ascorbic acid concentrations were significantly higher in males, whereas ascorbic acid synthesis and splenic and thymic ascorbic acid concentrations were significantly higher in females. 5. L-Gulonolactone oxidase activity was not detected in the comb of cockerels.  相似文献   

Arrhythmia: how do you solve these irregularities?     

Zandvliet M 《Tijdschrift voor diergeneeskunde》2007,132(12):491-494

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Total phenolic and lignin contents,phytochemical screening,antioxidant and fungal inhibition properties of the heartwood extractives of ten Congo Basin tree species     

Steeve Mounguengui  Jean-Bosco Saha Tchinda  Maurice Kor Ndikontar  Stéphane Dumarçay  Christiane Attéké  Dominique Perrin  Eric Gelhaye  Philippe Gérardin 《Annals of Forest Science》2016,73(2):287-296

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Biodiversity field trials to inform reforestation and natural resource management strategies along the African Great Green Wall in Senegal     

Thierno Ibrahima Wade  Ousmane Ndiaye  Margaux Mauclaire  Babacar Mbaye  Maurice Sagna  Aliou Guissé  Deborah Goffner 《New Forests》2018,49(3):341-362

Forest restoration is carried out with varying objectives in mind, one of which is biodiversity conservation. The present study examines the extent by which tree biodiversity could potentially be maximized in the context of the pan-African Great Green Wall for the Sahara and the Sahel Initiative (GGW). Towards this end, ten indigenous tree species were selected for study in the Ferlo region in Northern Senegal based on previous ethnobotanical studies in the zone. The species included Acacia senegal, Acacia nilotica, Acacia tortilis subsp. raddiana, Acacia seyal, Adansonia digitata, Balanites aegyptiaca, Dalbergia melanoxylon, Sclerocarya birrea, Tamarindus indica and Ziziphus mauritiana. Germination experiments were first performed in the laboratory on seed lots from Senegal, Burkina Faso, Kenya, and South Africa prior to in situ sapling production in the nursery in Northern Senegal situated along the GGW. A split plot field design was employed and the effects of seed provenance (two per species) and the addition of organic fertilizer at the timing of planting were determined. Over the course of the 2 year experimental period, the newly planted trees, in addition to the naturally regenerating woody vegetation and herbaceous grasses were monitored in the fenced-in experimental field plot. Of the ten species, only B. aegyptiaca, A. tortilis subsp. raddiana, and S. birrea exhibited moderate survival rates. The effects of provenance and fertilizer addition were sporadic and species-dependent. Natural regeneration of woody species was abundant albeit characterized by low biodiversity whereas herbaceous grass species showed extensive biodiversity, especially under tree canopies as compared to open areas.  相似文献   

Improving the biocontrol potential of entomopathogenic nematodes against Mamestra brassicae: effect of spray application technique,adjuvants and an attractant     

Bert Beck  Eva Brusselman  David Nuyttens  Maurice Moens  Femke Temmerman  Sabien Pollet  Stephanie Van Weyenberg  Pieter Spanoghe 《Pest management science》2014,70(1):103-112

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Sterols from the Madagascar sponge Fascaplysinopsis sp     

Aknin M  Gros E  Vacelet J  Kashman Y  Gauvin-Bialecki A 《Marine drugs》2010,8(12):2961-2975

The sponge Fascaplysinopsis sp. (order Dictyoceratida, Family Thorectidae) from the west coast of Madagascar (Indian Ocean) is a particularly rich source of bioactive nitrogenous macrolides. The previous studies on this organism led to the suggestion that the latter should originate from associated microsymbionts. In order to evaluate the influence of microsymbionts on lipid content, 10 samples of Fascaplysinopsis sp. were investigated for their sterol composition. Contrary to the secondary metabolites, the sterol patterns established were qualitatively and quantitatively stable: 14 sterols with different unsaturated nuclei, Δ(5), Δ(7) and Δ(5,7), were identified; the last ones being the main sterols of the investigated sponges. The chemotaxonomic significance of these results for the order Dictyoceratida is also discussed in the context of the literature. The conjugated diene system in Δ(5,7) sterols is known to be unstable and easily photo-oxidized during storage and/or experiments to produce 5α,8α-epidioxy sterols. However, in this study, no 5α,8α-epidioxysterols (or only trace amounts) were observed. Thus, it was supposed that photo-oxidation was avoided thanks to the natural antioxidants detected in Fascaplysinopsis sp. by both the DPPH and β-caroten bleaching assays.  相似文献