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排序方式: 共有148条查询结果,搜索用时 15 毫秒
21.
M. Brown R. Cox K. R. Bull H. Dyke G. Sanders D. Fowler R. Smith M. R. Ashmore 《Water, air, and soil pollution》1995,85(3):1485-1490
In Britain wheat is an important crop accounting for 41% of the total cereal production. In this study ozone concentrations for 1989 estimated as described in Part 1 of the paper are integrated with the estimated wheat distribution to derive a detailed estimate of the impact of ozone on wheat yields at a fine spatial scale (1km × 1km). These data provide estimates for calculating regional and national yield losses. The methodology can be applied to other crop species. Recent research on a range of crops has established relationships between the economic yield loss for certain crops, including wheat, and ozone exposure. Exposure is described as the accumulated exposure above a threshold experienced during the daylight hours (AOT). Critical AOT values are derived from yield exposure relationships which show linear reductions of yield loss with increasing ozone concentrations. This study has made use of land cover data from remotely sensed imagery at 25m resolution and nationally collected agricultural statistics for counties. These data were combined using an areal interpolation technique to provide more spatially articulate estimates of the location and intensity of wheat production. The results demonstrate the economic importance of ozone as a pollutant. Wheat yield losses attributed to ozone vary between different parts of the country but, for years when ozone levels are high, yield losses are likely to be significant in some areas. 相似文献
22.
Avsaroglu H Bull S Maas-Bakker RF Scherpenisse P Van Lith HA Bergwerff AA Hellebrekers LJ Van Zutphen LF Fink-Gremmels J 《Journal of veterinary pharmacology and therapeutics》2008,31(4):368-377
Medetomidine is an α2 -adrenoceptor agonist with sedative and analgesic properties. Previously we demonstrated significant differences in the response to medetomidine between two inbred rabbit strains, denoted IIIVO/JU and AX/JU. The aim of the present study was twofold: first, to compare the hepatic CYP450 enzyme activities between these rabbit strains [ n = 13(6♂♂,7♀♀)/strain]. To this end, liver microsomes were incubated with known fluorescent substrates for the major drug-metabolizing CYP450 isoforms. A comparison of the obtained results indicated significant gender differences as well as differences between the two rabbit inbred strains. Secondly, the biotransformation rate of medetomidine in liver microsomes of both rabbit strains was determined using liquid chromatography coupled to tandem mass spectrometry. The rate of hydroxymedetomidine and medetomidine carboxylic acid formation was found to be significantly higher in the AX/JU strain. Specific CYP2D and CYP2E inhibitors could decrease the formation of both metabolites. Significant correlations were found between the rate of biotransformation of medetomidine and the activities of CYP2D and CYP2E, as well as between CYP450 enzyme activities and the anaesthetic response to medetomidine. 相似文献
23.
Muller JD Wilks CR O'Riley KJ Condron RJ Bull R Mateczun A 《Australian veterinary journal》2004,82(4):220-222
OBJECTIVE: To evaluate the specificity of an immunochromatographic test (ICT) for anthrax in cattle. DESIGN: A comparison of an ICT with blood smear and culture in uninfected cattle. PROCEDURE: Two hundred and forty blood samples were collected from dead cattle at two knackeries within Victoria and tested on-site with an ICT for the detection of protective antigen (PA) of Bacillus anthracis. Blood smears were prepared on-site and blood samples transported to the laboratory for aerobic and anaerobic culture. The results of the ICT were compared with blood smear and culture. Animals were regarded as not infected with B anthracis if the organism was not detected in a stained blood smear or on culture. Ten healthy yearling cattle were vaccinated with live spore anthrax vaccine and blood samples collected on days 0 to 7 and day 15 were tested in the ICT for the presence of PA. RESULTS: All blood samples from the 240 knackery cattle were ICT, smear and culture negative. All blood samples from the 10 vaccinated cattle were ICT negative. CONCLUSION: The ICT is a test with high specificity in cattle (98.5 to 100%; 95% CI) and recent vaccination of cattle does not give rise to positive reactions. 相似文献
24.
Laan TT Bull S van Nieuwstadt RA Fink-Gremmels J 《Veterinary research communications》2006,30(6):623-635
β-Agonists have been shown to display anti-inflammatory properties in several experimental models. The aim of this study was
to investigate the anti-inflammatory properties of clenbuterol (CB), administered either intravenously or by aerosol, in comparison
with fluticasone propionate (FP) in recurrent airway obstruction (RAO)-susceptible horses. Eight horses, of which five were
known to be susceptible to RAO, underwent an inhalation challenge with Aspergillus fumigatus (AF) antigen and were treated with CB intravenously, CB by aerosol, or FP by aerosol. Twenty-four hours after the challenge,
bronchoalveolar lavage was performed, the total and differential cell counts were assessed, and cytokines were measured in
isolated alveolar macrophages. After challenge with AF, RAO-susceptible horses showed an increase in total cell count, based
on an increase in macrophages and lymphocytes, which was inhibited by treatment with intravenous CB, aerosolized CB and aerosolized
FP. Neutrophil ratios were decreased when treated with aerosolized CB and FP. Expression of interleukin (IL)-1β and IL −8
was significantly increased after AF challenge .Interleukin −1β was significantly decreased following treatment with intravenous
CB, aerosolized CB and aerosolized FP, whereas only FP decreased the expression of IL-8. These data suggest that the anti-inflammatory
property of CB provide new opportunities in the therapeutic intervention of early inflammation in RAO. 相似文献
25.
Effects of maternal protein-energy malnutrition and cold stress on neutrophil function of bovine neonates 总被引:1,自引:0,他引:1
L F Woodard W P Eckblad D P Olson R C Bull D O Everson 《American journal of veterinary research》1980,41(8):1208-1211
The effects of maternal protein or calorie deprivation (or both) on the bactericidal activity of neutrophils and sera from newborn calves subjected to cold stress were studied. Nutritional deficiencies in the dam had little effect on in vitro bactericidal activity of neutrophils and base-line sera taken at birth. Neutrophils obtained at birth destroyed Staphylococcus aureus but not Escherichia coli when incubated with either unheated or heated autologous base-line sera. Heat treatment of base-line sera to inactivate complement did not alter bacterial growth. When incubated in the presence of autologous base-line sera, neutrophils from 3-day-old calves were no more active in the destruction of either bacterium than were neutrophils from newborn calves. However, addition of day 3 (immunoglobulin-containing) sera enabled day 3 neutrophils to destroy E coli (P < 0.0001). The increased destruction of E coli by day 3 neutrophils and day 3 sera was not affected by heat treatment of the sera. Maternal protein deficiency significantly increased (P < 0.05) destruction of E coli by day 3 neutrophils and sera. This effect was independent of energy levels. There were no differences observed in the bactericidal activity of neutrophils and sera taken from calves exposed to 1 C or 21 C environmental chambers for 3 days. Also, cold stress-nutritional stress interactions were not detected. 相似文献
26.
Michael J. Bull J. Hugh Davies Robert J. G. Searle Arthur C. Henry 《Pest management science》1980,11(2):249-256
The alkyl phenyl ketone oxime O-benzyl ethers are a new group of insecticidal compounds. Although they lack the ester linkage, they resemble the pyrethroids in general, and the esters of 2-phenylalkanoic acids, in particular fenvalerate, because they show similar physiological effects on isolated nerve preparations and on whole insects; they also show a similar pattern of change of biological activity in response to structural change. The compounds may exist as two geometric isomers, of which only the (E) series shows significant biological activity; this observation appears to have some bearing on the relationship between conformation and activity in the pyrethroid series as a whole. 相似文献
27.
Tim J Bull Christina Vrettou Richard Linedale Catherine McGuinnes Sam Strain Jim McNair Sarah C Gilbert Jayne C Hope 《Veterinary research》2014,45(1)
Vaccination is the most cost effective control measure for Johne’s disease caused by Mycobacterium avium subspecies paratuberculosis (MAP) but currently available whole cell killed formulations have limited efficacy and are incompatible with the diagnosis of bovine tuberculosis by tuberculin skin test. We have evaluated the utility of a viral delivery regimen of non-replicative human Adenovirus 5 and Modified Vaccinia virus Ankara recombinant for early entry MAP specific antigens (HAV) to show protection against challenge in a calf model and extensively screened for differential immunological markers associated with protection. We have shown that HAV vaccination was well tolerated, could be detected using a differentiation of infected and vaccinated animals (DIVA) test, showed no cross-reactivity with tuberculin and provided a degree of protection against challenge evidenced by a lack of faecal shedding in vaccinated animals that persisted throughout the 7 month infection period. Calves given HAV vaccination had significant priming and boosting of MAP derived antigen (PPD-J) specific CD4+, CD8+ IFN-γ producing T-cell populations and, upon challenge, developed early specific Th17 related immune responses, enhanced IFN-γ responses and retained a high MAP killing capacity in blood. During later phases post MAP challenge, PPD-J antigen specific IFN-γ and Th17 responses in HAV vaccinated animals corresponded with improvements in peripheral bacteraemia. By contrast a lack of IFN-γ, induction of FoxP3+ T cells and increased IL-1β and IL-10 secretion were indicative of progressive infection in Sham vaccinated animals. We conclude that HAV vaccination shows excellent promise as a new tool for improving control of MAP infection in cattle.
Electronic supplementary material
The online version of this article (doi:10.1186/s13567-014-0112-9) contains supplementary material, which is available to authorized users. 相似文献28.
Policies Affecting Forestry Entrepreneurship 总被引:1,自引:0,他引:1
Anssi Niskanen Anders Lunnan Ikuo Ota Keith Blatner John Herbohn Lyndall Bull Ian Ferguson Gordon M. Hickey 《Small-Scale Forestry》2007,6(3):233-255
Many demand and supply-side policies impede or foster forestry entrepreneurship. A study was conducted to consolidate existing knowledge on policies influencing forestry entrepreneurship
in Finland, Norway, Japan, Australia, the Philippines and the USA, and to draw conclusions on these impeding and fostering
factors. From the country studies it was difficult to find common structures on policies affecting forestry entrepreneurship.
This is understandable because most policies in forestry are aimed at supporting sustainable forest management, wood production
and ecological services of the forests rather than entrepreneurship as such. Despite the high variety of policies applied
in the study countries, it can be concluded that strict public control on forests’ use and management potentially impedes
forestry entrepreneurship. While these policies assist to correct market failure and to promote sustainability of forest management,
they may also result into unnecessary and ineffective regulations that limit the opportunities for forestry entrepreneurship.
A common feature promoting the demand for forestry entrepreneurship in some of the countries studied is the strong emphasis
on forestry cooperatives, which were important institutions to support small-scale forestry entrepreneurship. In many study
countries, different ad hoc programs are implemented to find new economic and entrepreneurial opportunities aside from the
current use of wood and forests. Subsidies and tax incentives are commonly applied to reduce risks from making forestry investments
or otherwise increase the economic return from timber production. 相似文献
29.
Protein concentration was determined, using the Bradford technique, in tears from cats with normal corneas and from cats with corneal sequestrum. Tears from the former group contained 5.81 +/- 2.29 mg of protein/ml; those from corneal sequestrum-affected cats contained 6.21 +/- 2.21 mg/ml. Difference between the 2 values was not significant. Molecular weight determination was made, using 4 to 20% sodium dodecyl sulfate-polyacrylamide gels. Molecular mass of proteins ranged from 263 to 14 kDa. There was no detectable difference in the band patterns for the 2 groups. 相似文献
30.
Peripheral lymphocyte function in dogs with Brucella canis infection was evaluated using in vitro lymphocyte stimulation with the mitogens PHA, Con A and PWM, and killed Brucella canis organisms. Bitches with naturally occurring Brucella canis infection were compared to negative controls. There was no difference in the response to Con A and PWM between these two groups. Lymphocytes from infected dogs were less responsive (p less than .05) to PHA than were lymphocytes from controls. There was a significant (p less than .005) difference in response to Brucella canis antigen between the two groups. Lymphocytes from infected dogs were stimulated by Brucella canis antigen, whereas those from controls did not respond. 相似文献