The kinetics of insecticide action. Part IV: the in-vivo distribution of pyrethroid insecticides during insect poisoning     

Richard Greenwood  Martyn G. Ford  Edwin A. Peace  David W. Salt 《Pest management science》1990,30(1):97-121

The distribution of pyrethroids in insects has been studied using a combination of mathematical modelling and experimental observation. This approach has resulted in the formulation of a physiological model of the pharmaco-kinetics of cypermethrin applied topically to larvae of Spodoptera littoralis. Development of this model from simpler two- and three-compartment models is described. Simple models, whilst capable of complex behaviour, consider only the average rates and magnitudes of pharmaco-kinetic processes over whole animals, and cannot account for differences in concentration of insecticide between individual tissues. This can be achieved by using physiological models, but these require more experimental information for their validation. Moreover, unless simplifying assumptions are made, analytical solutions are not feasible for the large number of equations necessary to define such models. The modelling studies prompted an investigation of (1) in-vivo binding of insecticide to insect tissues, (2) the sizes of body compartments, and (3) the factors which affect the distribution of toxicant between these compartments. Binding has a marked effect on pharmacokinetic profiles and may result in oscillatory behaviour. During poisoning, the total bound cypermethrin increases proportionally to the cube root of the elapsed time. This results in a rapid rate of increase over early elapsed times (< 3h) which slows to approach a more linear form thereafter. Average sizes for the body compartments of larvae of Spodoptera littoralis Boisd, and the steady-state distribution of cypermethrin in these compartments are described. Although the haemolymph, which acts as the main distributive phase during poisoning, forms the largest compartment by volume, it has a low affinity for cypermethrin and distribution reaches steady state within 5 min after topical application. The nerve cord (the target tissue), which is the smallest compartment, has the highest steady-state concentration of cypermethrin. The distribution of cypermethrin in larval tissues is related to the ratios of tissue dry matter to water content.  相似文献   

Carcinogen in rock fern (Chielanthes sieberi) from New Zealand and Australia     

BL SMITH  PP EMBLING  DR LAUREN  MP AGNEW  AD ROSS  PL GREENTREE 《Australian veterinary journal》1989,66(7):230-231

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Further studies on the use of synthetic prostaglandin analogues for inducing luteolysis in mares   总被引：2，自引：0，他引：2  

W R Allen  F Stewart  M J Cooper  R C Crowhurst  D J Simpson  R J McEnery  R E Greenwood  P D Rossdale  S W Ricketts 《Equine veterinary journal》1974,6(1):31-35

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Herpesvirus B in macaque monkeys     

Greenwood A 《The Veterinary record》2002,151(17):516

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Reduction and recovery of N-acetylglucosamine-1-phosphate transferase activity in the liver of sheep and rats after a single subcutaneous dose of tunicamycin     

PL STEWART  C MAY CSIRO  MV JAGO 《Australian veterinary journal》1998,76(4):287-288

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Efficacy of feline panleucopenia vaccine to prevent infection with an isolate of CPV2b obtained from a cat.     

W S Chalmers  U Truyen  N M Greenwood  W Baxendale 《Veterinary microbiology》1999,69(1-2):41-45

Cats vaccinated against FPLV were protected against infection with a feline isolate of CPV2b. Nonvaccinated cats developed a lymphopenia and excreted virus which infected susceptible in-contact cats.  相似文献   

Dynamic model for the effects of K fertilizer on crop growth, K-uptake and soil-K in arable cropping. 2. Field test of the model     

D. J. Greenwood  T. V. Karpinets 《Soil Use and Management》1997,13(4):184-189

Abstract. The validity of the model described in Greenwood & Karpinets (1997) was tested against the results of single year, multi level K fertilizer experiments. Measurements of plant mass, %K in the plant and K activity ratio in soil had been made at harvest and at intervals during the growing season on spring wheat, summer cabbage and turnips. Reasonably good agreement was obtained between these measurements and simulated values when the two 'crop' parameters (defining the dependence of critical and maximum possible %K on plant mass) were adjusted for each crop. Also good agreement was generally obtained for plant weight and plant %K at harvest in less detailed experiments on 10 other crops. Values of the two 'crop' parameters for 12 of the crops were strongly correlated with one another suggesting that a single 'crop' parameter may be all that is required to define most inter-species differences in plant-K demand.
Simulations with the model indicate that, in central England, no response of 10 crops to K fertilizer would be likely on soils containing more than 170 mg of 1 M ammonium nitrate extractable-K/kg of soil and having clay contents of between 15 and 45%. Shortcomings of the model and opportunities for advance are discussed.
A simplified version of the model runs on the Internet at: http://www.qpais.co.uk/moda-djg/potass.htm  相似文献   

Six cases of degenerative joint disease of the proximal interphalangeal joint of young Thoroughbreds     

D R Ellis  R E Greenwood 《Equine veterinary journal》1985,17(1):66-68

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Age- and size-related trends in woody plant shoot development: regulatory pathways and evidence for genetic control     

Day ME  Greenwood MS  Diaz-Sala C 《Tree physiology》2002,22(8):507-513

Woody plants exhibit significant and predictable patterns of change in morphology and physiology as they become older and larger. Four models of potential pathways controlling these changes are presented: a stimulus-response model in which fully developed organs respond to changes in environment (defined here as everything external to the organ); an extrinsic model in which the attributes of developing organs are determined by environmental factors; an intrinsic model in which changes are a result of programmed changes in gene expression; and an extrinsic-intrinsic model in which changes in gene expression are induced by environmental factors. We review evidence that a genetic component is involved in controlling age- and size-related changes in foliar morphology and physiology and discuss the possibility of complex interactions among model pathways.  相似文献   

Uptake and translocation of non-ionised pesticides in the emergent aquatic plant parrot feather Myriophyllum aquaticum     

de Carvalho RF  Bromilow RH  Greenwood R 《Pest management science》2007,63(8):798-802

The uptake of four (14)C-labelled non-ionised compounds, the methyl carbamoyloxime insecticide/nematicide oxamyl and three model phenylureas, from solution by rooted stems of the aquatic plant parrot feather [Myriophyllum aquaticum (Vell.) Verdc], together with translocation to the emergent shoots, was measured over periods of 24 and 48 h. Uptake into the submerged tissues of roots and stem base could be ascribed to two processes: movement into the aqueous phase of cells and then partitioning onto the plant solids. This latter process was related to lipophilicity (as measured by the l-octanol/water partition coefficient, K(ow)) and gave rise to high uptake rates of the most lipophilic compounds. Translocation to shoots was passive and was optimal at log K(ow) approximately 1.8, at which the efficiency of translocation of compound was about 40% of that of water. This optimum log K(ow) was identical to that observed previously in barley, although the translocation efficiency was somewhat less in parrot feather. Solvation parameters were applied to model uptake and translocation of a set of ten compounds by barley with the particular objective of understanding why translocation efficiency is lower at log K(ow) > 1.8.  相似文献