Values of urine specific gravity for thoroughbred horses treated with furosemide prior to racing compared with untreated horses.     

Noah D Cohen  Kenneth E Peck  Sarah A Smith  Allen C Ray 《Journal of veterinary diagnostic investigation》2002,14(3):231-235

The distribution of specific gravity values for 2,599 urine samples collected from racing Thoroughbred horses that were known to have received furosemide prior to racing was compared with that for 1,669 urine samples from racing Thoroughbred horses that reportedly had not received furosemide. Values of specific gravity for furosemide-treated horses were significantly lower (P < 0.001) than those for horses that had not received furosemide, and the proportion of horses with urine specific gravity either <1.010 or <1.012 was significantly greater (P < 0.001) among the furosemide-treated horses. These data indicate that evaluation of urine specific gravity would be a useful component of drug testing programs for regulation of furosemide use.  相似文献   

Colchicine-induced heritable variation in cell size and chloroplast number in the leaf cells of inbred ryegrasses (Lolium perenne,L. multiflorum)     

Lutful Hassan  R. N. Jones  J. S. Parker  U. K. Posselt 《Euphytica》1991,52(1):39-45

Summary A 3 hr period of treatment with a 0.2% aqueous solution of colchicine was given to one week old seedlings of 3 inbred lines of perennial ryegrass (Lolium perenne) and 4 lines of Italian ryegrass (L. multiflorum). The surviving plants developed as mixoploids and were self-pollinated. In the following generation (CT1) the seeds were grown without further treatment, and were screened cytologically at the seedling stage to separate out diploids from tetraploids. Only the diploids were kept, and in this CT1 generation comparisons were then made between controls (2x) and colchicine-treated diploids (C2x) for leaf mesophyll cell size and chloroplast number variation. Heritable differences were found such that the cell plan areas and/or the numbers of chloroplasts per cell were significantly greater in the C2x compared with the 2x treatment in 3 and 5 out of the 7 lines. In each case there was enhancement of chloroplast numbers independently of the variation in cell size.  相似文献   

The effect of cooking on chlorpyrifos and 3,5,6-trichloro-2-pyridinol levels in chlorpyrifos-fortified produce for use in refining dietary exposure   总被引：2，自引：0，他引：2  

Byrne SL  Pinkerton SL 《Journal of agricultural and food chemistry》2004,52(25):7567-7573

Various types of produce were fortified with chlorpyrifos and then boiled, baked, canned, or concentrated as appropriate for the type of produce. Both uncooked and cooked samples were analyzed for chlorpyrifos and 3,5,6-trichloro-2-pyridinol, and then, chlorpyrifos cooking factors were calculated by comparing the postcooked concentration to the uncooked concentration. The cooking factors were dependent upon the commodity and cooking procedure: 0.320-1.19 for boiled samples, 0.022-1.18 for baked pulp, and 0.119-0.661 for canned samples. Concentrating chlorpyrifos-fortified orange juice 4-fold resulted in a concentration factor of only 2.6, indicating a loss of chlorpyrifos. Green bean and green pepper plants treated in the greenhouse yielded higher chlorpyrifos concentrations but similar cooking factors to lab-fortified samples. The cooking factors can be used with food consumption databases and modeling tools to refine the dietary exposure according to current product label uses.  相似文献   

Critical evaluation of three indirect assays for quantifying phytosiderophores released by the roots of Poaceae     

S. M. Reichman  & D. R. Parker 《European Journal of Soil Science》2007,58(3):844-853

Indirect assays are commonly used to measure phytosiderophore (PS) concentrations in the root exudates of grasses. The Cu‐mobilizing, Cu‐CAS and Fe‐binding assays are three commonly used assays but there have been few published attempts to validate or calibrate them rigorously. Thus, we undertook to compare, validate and, where appropriate, to improve and/or optimize each assay. Ethylenediamine‐N,N′‐diacetic acid (EDDA) and N‐2‐hydroxyethylethylenediamine‐N,N′,N′‐triacetic acid (HEDTA) bracket deoxymugineic acid for binding strength with both Fe and Cu and were thus used as model ligands. For the Cu‐mobilizing assay, reasonable regressions (as R²) were obtained between measured and known ligand concentrations for all resin combinations tested. However, the relationship was non‐stoichiometric; less than 5% of the ligand present was recovered as a Cu‐complex. Testing of the Cu‐CAS assay yielded good 1:1 stoichiometric relationships (slopes of 0.97 and 1.08 for EDDA and HEDTA, respectively) with little scatter (R²= 0.97). However, the limits of quantification were approximately 30 μm , which is greater than concentrations generally found in root‐exudate collections. Thus, the Cu‐CAS assay is best suited to situations where large concentrations of PSs are expected. Results from the original Fe‐binding assay indicated a lack of linearity and considerable scatter (R²= 0.57 for EDDA; R²= 0.28 for HEDTA). Thus, as published, use of the original Fe‐binding assay is not recommended. The effects of filter paper, FeCl₃ reagent concentration and increase in the reduction time were tested and a revised Fe‐binding assay developed with both good stoichiometry and great precision (R²≥ 0.99). We suggest the use of the revised Fe‐binding assay in most situations where PS concentration would be expected to be < 30 μm .  相似文献   

Multidimensional gas chromatography-olfactometry for the identification and prioritization of malodors from confined animal feeding operations     

Wright DW  Eaton DK  Nielsen LT  Kuhrt FW  Koziel JA  Spinhirne JP  Parker DB 《Journal of agricultural and food chemistry》2005,53(22):8663-8672

Odor profiling efforts were directed at applying to high-density livestock operations some of the lessons learned in resolving past, highly diverse, odor-focused investigations in the consumer product industry. Solid-phase microextraction (SPME) was used for field air sampling of odorous air near and downwind of a beef cattle feedyard and a swine finisher barn in Texas. Multidimensional gas chromatography-olfactometry (MDGC-O) was utilized in an attempt to define and prioritize the basic building blocks of odor character associated with these livestock operations. Although scores of potential odorant volatiles have been previously identified in high-density livestock operations, the odor profile results developed herein suggest that only a very few of these may constitute the preponderance of the odor complaints associated with these environments. This appeared to be especially true for the case of increasing distance from both cattle feedyard and swine barn facilities, with p-cresol consistently taking on the dominant odor impact role with ever increasing distance. In contrast, at- or near-site odor profiles were shown to be much more complex, with many of the well-known lower tier odorant compounds rising in relative significance. For the cattle feedyard at- or near-site odor profiles, trimethylamine was shown to represent a significantly greater individual odor impact relative to the more often cited livestock odorants such as hydrogen sulfide, the organic sulfides, and volatile fatty acids. This study demonstrates that SPME combined with a MDGC-O-mass spectrometry system can be used for the sampling, identification, and prioritization of odors associated with livestock.  相似文献   

Rupture of nodule bacteria on drying and rehydration     

M.P. Salema  C.A. Parker  D.K. Kidby  D.L. Chatel  T.M. Armitage 《Soil biology & biochemistry》1982,14(1):15-22

A mathematical model predicting the likely morphological effects of drying and rehydration of rhizobial cells on seed has been developed and tested. The results agree with the predictions made from the model in that drying by itself did not morphologically affect cells of Rhizobium trifolii WU1 (= TA1): it was the combined processes of drying and rehydration that resulted in rupture of the cell envelope. Cells ruptured on the subpolar region which is also the region from which flagella originate. A suggestion is made that the point where a flagellum emerges from the cell is a point of weakness.  相似文献   

A hierarchical model for compositional data analysis     

Mark?J.?BrewerEmail author  Jo?o?A.?N.?Filipe  David?A.?Elston  Lorna?A.?Dawson  Robert?W.?Mayes  Chris?Soulsby  Sarah?M.?Dunn 《Journal of Agricultural, Biological & Environmental Statistics》2005,10(1):19-34

This article introduces a hierarchical model for compositional analysis. Our approach models both source and mixture data simultaneously, and accounts for several different types of variation: these include measurement error on both the mixture and source data; variability in the sample from the source distributions; and variability in the mixing proportions themselves, generally of main interest. The method is an improvement on some existing methods in that estimates of mixing proportions (including their interval estimates) are sure to lie in the range [0, 1]; in addition, it is shown that our model can help in situations where identification of appropriate source data is difficult, especially when we extend our model to include a covariate. We first study the likelihood surface of a base model for a simple example, and then include prior distributions to create a Bayesian model that allows analysis of more complex situations via Markov chain Monte Carlo sampling from the likelihood. Application of the model is illustrated with two examples using real data: one concerning chemical markers in plants, and another on water chemistry.  相似文献   

Phosphate inflow into Trifolium subterraneum L.: Effects of photon irradiance and mycorrhizal infection     

Mark Tester  F.Andrew Smith  Sarah E. Smith 《Soil biology & biochemistry》1985,17(6):807-810

Plants grown at reduced photon irradiances have a reduced growth response to mycorrhizal infection over non-mycorrhizal controls. Although phosphate inflow is reduced with reduced photon irradiance (and even becomes negative in plants grown at 20 μmol m^?2 s^?1), the reduced growth response is not due to a P starvation of plants, as all mycorrhizal plants were sufficient in P. This was largely because the plants were still influenced by phosphate stored in the seed. It is likely that the decreased growth response with decreased photon irradiance is due to an increased significance of the carbohydrate drain by the fungus.  相似文献   

Alternative method for the quantification by gas chromatography triacylglycerol class analysis of cocoa butter equivalent added to chocolate bars     

Guyon F  Destouesse S  Moustirats J  Esclapez M  Salagoity MH  Medina B 《Journal of agricultural and food chemistry》2004,52(10):2770-2775

Directive 2000/36/EC allows chocolate makers to add up to 5% of only six specific cocoa butter equivalents (CBEs) to cocoa butter (CB). A quantification method based on triacylglycerol (TAG) class analysis by gas chromatography with an unpolar column was set up for routine control purposes of chocolate bars. Mixtures of CBEs/CB were elaborated according to a Placket-Burman experiment design and analyzed by gas chromatography. A matrix was built with the normalized values of TAG classes (C50, C52, C54, and C56) of pure CBs of various origins, homemade CB/CBE mixtures (1 CB type), and mixtures containing CBE with CBs of various origins. A multivariate calibration equation was computed from this matrix using a partial least-squares regression technique. CBE addition can be detected at a minimum level of 2%, and the mathematical model allows its quantification with an uncertainty of 2% with respect to the cocoa butter fats. The model has also been applied for deconvolution and quantification of each CBE of a CBE mixture in chocolate bars.  相似文献   

Spatial and temporal variability of urban soil water dynamics observed by a soil monitoring network     

Sarah Wiesner  Alexander Gröngröft  Felix Ament  Annette Eschenbach 《Journal of Soils and Sediments》2016,16(11):2523-2537

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