Bovine anaplasmosis: susceptibility of seronegative cows from an infected herd to experimental infection with Anaplasma marginale     

S D Lincoln  J L Zaugg  J Maas 《Journal of the American Veterinary Medical Association》1987,190(2):171-173

Adult cows from an Anaplasma marginale-infected herd that were negative to the A marginale rapid card agglutination (RCA) and complement fixation (CF) tests for 1 to 4 years developed acute anaplasmosis after inoculation with 0.5 ml of blood from an A marginale carrier cow. The test cattle were as susceptible as the control cattle of similar ages. Also, 2 cows that had seroconverted from RCA/CF-positive to RCA/CF-negative status naturally were fully susceptible to anaplasmosis when they were experimentally infected. Results of the study indicated that indigenous seronegative cattle in anaplasmosis-enzootic regions probably do not have acquired or natural immunity to A marginale infection.  相似文献   

Inhibition of aflatoxin M1 production by bovine hepatocytes after intervention with oltipraz     

Kuilman ME  Maas RF  Woutersen-van Nijnanten FM  Fink-Gremmels J 《The Veterinary quarterly》2000,22(1):30-35

It is well known that cattle ingesting aflatoxin B1 contaminated feed commodities excrete aflatoxin M1 into their milk. As aflatoxin M1 originates from hepatic metabolism, measures to prevent aflatoxin M1 formation need to be directed to either the immobilization of aflatoxin B1 in the gastrointestinal tract or the modification of hepatic metabolism of aflatoxin B1. Here we studied the influence of oltipraz and a second dithiolthione, (1,2) dithiolo (4,3-c)-1,2-dithiole-3,6 dithione (DDD) on bovine hepatic aflatoxin B1 biotransformation. Oltipraz inhibited aflatoxin B1 metabolism as no aflatoxin M1 and no aflatoxin B1-dihydrodiol, the second metabolite found in bovine hepatocytes, was formed. DDD did not significantly inhibit aflatoxin B1 metabolism. It could be demonstrated that the inhibition of aflatoxin B1 metabolism was due to the inhibition of several cytochrome P450 enzyme activities by oltipraz. In contrast, DDD inhibited only ethoxyresorufin O-deethylation activity. These findings suggest a high efficacy of oltipraz in inhibiting aflatoxin M1 contamination of milk from dairy cows exposed to aflatoxin B1 contaminated feeds.  相似文献   

Antigen quantification as in vitro alternative for potency testing of inactivated viral poultry vaccines     

Maas RA  de Winter MP  Venema S  Oei HL  Claassen IJ 《The Veterinary quarterly》2000,22(4):223-227

Routine batch control of licensed inactivated viral vaccines for poultry usually includes a potency assay as a measure of vaccine efficacy. Potency assays often consist of vaccination-challenge experiments in the target species or in laboratory animals. Instead of measuring the protection of vaccinated animals against virulent pathogens, the serological response after vaccination can be quantified for some vaccines. In vitro antigen quantification assays would be attractive alternatives for the current potency assays because the time and costs involved could be greatly reduced and animal use could be avoided. Such in vitro assays will only be acceptable when the correlation between results and efficacy or potency has been demonstrated convincingly. The results of our studies on antigen quantification assays indicate that, in principle, quantification of viral antigens from inactivated oil-adjuvanted vaccines is feasible and reproducible using specially developed antigen capture ELISAs in combination with specific software for statistical analysis of the ELISA data. We have developed methods to quantify the haemagglutination-neuraminidase (HN) and fusion (F) proteins of Newcastle disease virus (NDV), the viral protein 3 (VP3) of the infectious bursal disease virus (IBDV), and the spike-1 (S1) protein of the infectious bronchitis virus (IBV). Vaccination experiments with inactivated ND vaccines indicate that the in vitro quantified HN- or F-proteins of NDV are reliable indicators of the serological response after vaccination.  相似文献   

Serogroups of Australian isolates of Serpulina hyodysenteriae     

DJ HAMPSON  CD MALTAS  CP STEPHENS  K. McKECHNIE  NB BULLER 《Australian veterinary journal》1994,71(10):347-347

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Pyrenophora calvescens op blauwmaanzaad     

H. P. Maas Geesteranus 《European journal of plant pathology / European Foundation for Plant Pathology》1960,66(4):237-248

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Hostplants ofAgrobacterium gypsophilae     

H. P. Maas Geesteranus  Hetty Barendsen 《European journal of plant pathology / European Foundation for Plant Pathology》1966,72(3-6):231-232

Symptoms obtained after either natural or artificial infection on roses, carnations and cacti byAgrobacterium gypsophilae are described, as well as a modification of the isolation method for this pathogen.  相似文献   

Copper toxicosis in two herds of beef calves following injection with copper disodium edetate     

F D Galey  J Maas  R J Tronstad  L W Woods  B J Johnson  E S Littlefield  R Wallstrum  L C Dorius 《Journal of veterinary diagnostic investigation》1991,3(3):260-263

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Salt sensitivity of corn at various growth stages     

E. V. Maas  G. J. Hoffman  G. D. Chaba  J. A. Poss  M. C. Shannon 《Irrigation Science》1983,4(1):45-57

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Salt sensitivity of cowpea at various growth stages     

E. V. Maas  J. A. Poss 《Irrigation Science》1989,10(4):313-320

Summary The relative salt tolerance of cowpea (Vigna unguiculata (L.) Walp. cv. California Buckeye No. 5) at different stages of growth was determined in a greenhouse. Plants were grown in sand cultures that were irrigated four times daily with modified half-strength Hoagland's solution. Salination with NaCl and CaCl₂ (2:1 molar ratio) provided seven treatment solutions with osmotic potentials (_s) ranging from –0.05 to –1.05 MPa (electrical conductivities of 1.4 to 28 dS/m). Salt stress was imposed for 20 days beginning at either 7, 27, or 52 days after planting. The three 20-day stages are referred to here as vegetative, flowering, and pod filling stages. Pod and seed yields from plants stressed during either the vegetative, flowering, or pod-filling stages indicated that cowpea was the most sensitive to salinity during the vegetative stage and became less sensitive the later plants were stressed. Seed yield was reduced 50% at _s =–0.45, –0.76, and –0.88 MPa for plants salinized during the vegetative, flowering, and pod-filling stages, respectively. Salinity reduced seed yield by reducing seed number; it had little, if any, effect on the weight of individual seeds. Vegetative growth was significantly reduced by salt stress during all three stages but the effect was much less when stress was imposed during the last two stages than during the first stage.  相似文献   

Characterization of Copper Algaecide (Copper Ethanolamine) Dissipation Rates Following Pulse Exposures     

Alyssa J. Calomeni  Kyla J. Iwinski  Andrew D. McQueen  Ciera M. Kinley  Maas Hendrikse  John H. RodgersJr. 《Water, air, and soil pollution》2017,228(11):444

Dissipation rates of copper following algaecide treatments resulting in pulse exposures can be accurately modeled if the component dissipation rates are known. Scaled experiments (in situ, laboratory and mesocosm) were used to parse and rank dominant processes from concurrent processes affecting copper fate in pulse exposures. Copper dissipation rates were measured cumulatively in situ and in mesocosms as well as individually in laboratory experiments. Predictions of the influence of individual dissipation rates on the cumulative dissipation rate were assessed mathematically. In situ aqueous copper dissipated rapidly following an algaecide treatment, with a measured half-life of 0.03 days. Based on laboratory experiments, the most rapid copper fate process was dilution with a half-life of 0.03 days, followed by sediment sorption with a half-life of approximately 3 days. Mesocosm experiments incorporating physical characteristics of the site (i.e., dilution, sediment, algae, and site water) resulted in similar copper dissipation rates (0.02 days) relative to the in situ copper dissipation rate. Prediction of the fate of copper from algaecide treatments requires incorporation of accurate estimates of dominant fate processes that can be determined physically and mathematically.  相似文献