Detection and quantification of antibodies to infectious bronchitis virus by enzyme-linked immunosorbent assay   总被引：3，自引：0，他引：3  

W W Marquardt  D B Snyder  B A Schlotthober 《Avian diseases》1981,25(3):713-722

An enzyme-linked immunosorbent assay (ELISA) for detecting and quantifying antibodies to infectious bronchitis virus (IBV) is described. Purified antigen, prepared on sucrose density gradients, was required to decrease the nonspecific background, and saline was found to be superior to bicarbonate buffer for coating the cuvettes with antigen. The sensitivity of the test in measuring antiserum titers could be altered greatly and linearly by adjusting the protein content of the antigen. The ELISA was able to detect an antibody response to IBV infection earlier than the virus-neutralization (VN) test. Antibody titers obtained by ELISA were considerably higher than those obtained by VN. Serotypes of IBV could not be differentiated with ELISA because of extensive antiserum cross-reactivity. The utility of ELISA in studies on IBV is discussed.  相似文献   

Influence of dietary charcoal on ochratoxin A toxicity in Leghorn chicks.          下载免费PDF全文

R G Rotter  A A Frohlich    R R Marquardt 《Canadian journal of veterinary research》1989,53(4):449-453

The ability of activated charcoal to adsorb ochratoxin A (OA) in vitro and to reduce the toxic effects of OA in vivo when added to the diet of growing Leghorn chicks was studied. Activated charcoal (50 mg) was able to adsorb 90% of the OA (150 micrograms) contained in 10 mL of citrate-phosphate buffer (pH 7.0). When 2 g of a complete chick diet were mixed with OA in buffer, it adsorbed 66% of the OA, while addition of 50 mg of charcoal to this mixture further reduced the concentration of OA to 11.8% of the control, an additional 65% compared to the diet alone. In the first of two feeding studies, charcoal addition of up to 10,000 parts per million (ppm) to diets (6.7% tallow) containing 9.93 mumol (4 ppm) OA kg-1 diet had no effect on OA toxicity. Feed consumption and weight gain, however, were reduced 10 and 20%, respectively, in chicks fed diets which contained 10,000 ppm of charcoal compared to those fed no charcoal. In the second study, reducing dietary tallow to 2% did not alter the effects of OA or charcoal on weight gain and feed to gain ratio, but birds fed OA with 10,000 ppm charcoal had an 8.5% increase in feed consumption. An additional management problem was associated with the propensity of charcoal to blacken the feed, the birds and their environment. Addition of charcoal to OA contaminated diets appeared to be an ineffective method for reducing the toxic effects of OA in growing chicks.  相似文献   

A multi-institutional epidemiologic study evaluating environmental risk factors for feline oral squamous cell carcinoma     

Lucie Noall  Suhwon Lee  Jenna H. Burton  Taya M. Marquardt  Justin Cermak  Lori A. Thombs  Anita M. Rogic  Jeffrey N. Bryan  Shirley Chu 《Veterinary and comparative oncology》2023,21(3):509-519

Feline oral squamous cell carcinoma (FOSCC) is an aggressive cancer in domestic cats that has no effective treatment option when advanced. Preventative or early diagnostic measures are thus crucial. FOSCC is also a model for human head and neck SCC (HNSCC); strong risk factors in HNSCC include exposure to alcohol, tobacco, areca nut, and high-risk human papillomavirus. Previous studies have identified flea collar and tobacco smoke exposure, feeding canned tuna, canned cat food and cat foods with chemical additives, living in a rural environment, and having outdoor access as risk factors for FOSCC but there was no overlap in the risk factors between studies. In our study, risks for FOSCC were evaluated in an online epidemiologic survey study in 67 cats with FOSCC and 129 control cats. Clumping clay cat litter and flea collar use were significant risk factors for FOSCC on multiple logistic regression with odds ratios of 1.66 (95% CI 1.20–2.30) and 4.48 (95% CI 1.46–13.75) respectively. Crystalline silica is a carcinogen that may be present in all clay cat litters and tetrachlorvinphos is a carcinogen that is present in the most commonly used flea collars in our study. We recommend further investigation into the association between FOSCC and clay-based litter and/or flea collars containing tetrachlorvinphos.  相似文献   

Rat transforming growth factor type 1: structure and relation to epidermal growth factor   总被引：61，自引：0，他引：61  

H Marquardt  M W Hunkapiller  L E Hood  G J Todaro 《Science (New York, N.Y.)》1984,223(4640):1079-1082

The complete amino acid sequence of rat transforming growth factor type 1 has been determined. This growth factor, obtained from retrovirus-transformed fibroblasts, is structurally and functionally related to mouse epidermal growth factor and human urogastrone. Production of this polypeptide by various neoplastic cells might contribute to the continued expression of the transformed phenotype.  相似文献   

Long-term trends in chemistry of precipitation after longscale transport-effects of atmospheric rehabilitation in East-Germany     

Wolfgang Marquardt  Erika Brüggemann 《Water, air, and soil pollution》1995,85(2):665-670

Components in precipitation are dominantly dependent on structure and quantity of emissions on the course of the rainy air masses. It can be proved after meso-and long-range transport. Starting in 1982, precipitation is collected in 4-hour-periods at sites far from industry in East-Germany. For regions with specific geographical or uniform emission features arrival sectors are established, e. g. former GDR, Scandinavia, Poland, or Czech. The classification of the samples is done by back-trajectories. From the former GDR the anthropogenical components were most significantly raised before the political change, but acidity remained on an average level. After the change, the most emission products decline considerably —except NO_X. Consequently, those lead to essential changes of pollutants in precipitation. The reduction is not uniformly. The report represents long-term data and discusses clear differences between components in deposition from sectors of the former GDR and West-Germany. The effects of atmospheric rehabilitation are analysed. Specially starting in 1993 the acidity of rain from the former GDR increases very strikingly up to now threefold more than from West-Germany (average ≤pH 4 at some sites). An explanation in terms of emission components only is devious, a complex consideration of change of dust composition as neutralizing factors and of processes of cloud formation and dispersal is necessary. It must be mentioned, that the acidity of precipitation from West-Germany and Scandinavia declines slightly in recent period. Therefore only sector-classified data show the real range of acidity.  相似文献   

Effect of a hay and a grain diet on the rate of hydrolysis of ochratoxin A in the rumen of sheep   总被引：2，自引：0，他引：2  

H Xiao  R R Marquardt  A A Frohlich  G D Phillips  T G Vitti 《Journal of animal science》1991,69(9):3706-3714

The hydrolysis of ochratoxin A (OA) and the corresponding formation of its hydrolysis product, alpha ochratoxin (O alpha), by ruminal digesta and in the rumen of hay-fed and grain-fed sheep were compared. Ruminal contents from sheep fed diets with hay or with grain hydrolyzed OA in vitro; the majority of the activity was associated with the particulate fraction of the ruminal contents. The rate of hydrolysis of OA by ruminal fluid that was adjusted to different pH values was not influenced (P greater than .6) by the pH of the samples (pH was from 5.5 to 7.0). Ruminal fluid obtained from hay-fed animals (pH 7.0) was able to hydrolyze OA in vitro and to produce the hydrolyzed product, O alpha, at a much greater rate (fivefold) than ruminal fluid obtained from grain-fed animals (pH 5.5) (P less than .01). Ochratoxin A was administered intraruminally at a concentration of .5 mg/kg of BW to hay-fed and grain-fed sheep. The half-lives for disappearance of OA from the rumen of sheep fed grain (normal feed intake, rumen pH 5.7), fed grain at a low level (30% of normal feed intake, pH 6.5), and fed hay (pH 7.1) were 3.6, 1.3, and .6 h, respectively. The results suggest that OA is hydrolyzed much faster in the rumen of sheep fed hay than in sheep fed grain, presumably because of the different ruminal microbial population, which in turn influenced the rate of hydrolysis of OA.  相似文献   

Eosinophilic myositis and muscular sarcocystosis in the carcasses of slaughtered cattle and lambs   总被引：1，自引：0，他引：1  

R Jensen  A F Alexander  R R Dahlgren  W R Jolley  W C Marquardt  D E Flack  B W Bennett  M F Cox  C W Harris  G A Hoffmann 《American journal of veterinary research》1986,47(3):587-593

Fifty-three bovine and 7 ovine carcasses condemned for having eosinophilic myositis were evaluated. Four (7.3%) of the bovine carcasses had a few, large local lesions in skeletal muscles (category A), and 49 (92.7%) of the bovine carcasses and 7 (100%) of the ovine carcasses had multiple, small, disseminated lesions in tongue, esophagus, heart, diaphragm, or skeletal muscles (category B). Tissue from carcasses of category B were evaluated for bacteria, viruses, selenium, and pathologic changes. Pathogenic bacteria and viruses were not isolated and selenium concentrations were normal. In category B, all carcasses had granulomas; of the 49 bovine carcasses and 7 ovine carcasses, 38 (77.6%) and 7 (100%), respectively, had one or more granulomas with opened dead sarcocysts. The data indicated that opened sarcocysts killed the host myocyte and adjacent myocytes and stroma, thereby initiating granuloma formation.  相似文献   

Avian complement-fixation     

W W Marquardt 《Avian diseases》1973,17(1):236-250

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A direct complement-fixation test for detection of mycoplasma antibodies in chicken serum     

W W Marquardt  J A Newman 《Avian diseases》1971,15(1):139-149

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Improved fallows: a case study of an adaptive response in Amazonian swidden farming systems     

Kristina Marquardt  Rebecka Milestad  Lennart Salomonsson 《Agriculture and Human Values》2013,30(3):417-428

Many smallholders in the Amazon employ swidden (slash-and-burn) farming systems in which forest or forest fallows are the primary source of natural soil enrichment. With decreasing opportunities to claim natural forests for agriculture and shrinking landholdings, rotational agriculture on smaller holdings allows insufficient time for fallow to regenerate naturally into secondary forest. This case study examines how Peruvian farmers use “improved fallows” as an adaptive response to a situation of decreasing soil fertility and how the farmers describe the rationale underlying the various actions taken in these modified fallow systems. The results indicate that farmers establish improved fallows using contextual ecological knowledge and various techniques to introduce a large diversity of tree species. This practice is also used to restore degraded land to agricultural production. The tasks of maintaining productivity on agricultural land and reforesting degraded areas is becoming increasingly urgent in the Amazon, making agricultural practices that involve reforestation and tree management highly relevant. Since swidden farming systems are the basis for the livelihoods of most Amazon smallholders, good farming practices elaborated by swidden farmers are important for sustainable small-scale family farming systems in the Amazon.  相似文献