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91.
92.
Morphological diversity of Paramoeba perurans trophozoites and their interaction with Atlantic salmon,Salmo salar L., gills 下载免费PDF全文
J Wiik‐Nielsen T A Mo H Kolstad S N Mohammad S Hytterd M D Powell 《Journal of fish diseases》2016,39(9):1113-1123
Amoebic gill disease (AGD) caused by the ectoparasite Paramoeba perurans affects several cultured marine fish species worldwide. In this study, the morphology and ultrastructure of P. perurans in vitro and in vivo was investigated using scanning and transmission electron microscopy (SEM and TEM, respectively). Amoebae cultures contained several different morphologies ranging from a distinct rounded cell structure and polymorphic cells with pseudopodia of different lengths and shapes. SEM studies of the gills of AGD‐affected Atlantic salmon, Salmo salar L., revealed the presence of enlarged swellings in affected gill filaments and fusion of adjacent lamellae. Spherical amoebae appeared to embed within the epithelium, and subsequently leave hemispherical indentations with visible fenestrations in the basolateral surface following their departure. These fenestrated structures corresponded to the presence of pseudopodia which could be seen by TEM to penetrate into the epithelium. The membrane–membrane interface contained an amorphous and slightly fibrous matrix. This suggests the existence of cellular glycocalyces and a role for extracellular products in mediating pathological changes in amoebic gill disease. 相似文献
93.
Amara H. Estrada Herbert W. Maisenbacher III VMD Robert Prošek DVM MS Jesse Schold PhD Melanie Powell BS James M. VanGilder BS 《Journal of Veterinary Cardiology》2009,11(2):79-88
Objective
To compare left ventricular synchronization and systolic performance with transvenous pacing of the right ventricular apex (RVA), left ventricular free wall (LVF) or simultaneous pacing of the RVA and LVF (BiV).Animals, materials and methods
Seven canine patients with complete heart block. Prospective study evaluating effect of pacing site. Twenty four hours following implantation of transvenous BiV pacing systems, electrocardiograms and echocardiograms were assessed during pacing from the: (1) Right Atrial Appendage/RVA (RAA/RVA), (2) RAA/LVF, and (3) RAA/BiV.Results
QRS duration was significantly shorter with BiV pacing versus LVF pacing (p < 0.001), or RVA pacing (p < 0.001). Echocardiographic indices of systolic performance fractional shortening (FS), ejection fraction (EF), cardiac output (CO) were significantly higher with BiV pacing than with pacing from the RVA (P = 0.023, 0.006, and 0.002 respectively). Cardiac output, measured by the biplane Simpson's method, was higher with LVF versus RVA pacing (P = 0.036). There was no difference in FS or EF when comparing LVF to RVA pacing. Tissue Doppler measurements of synchronization and systolic performance did not show any difference between pacing mode, but a significantly increased number of segments were seen to contract following aortic valve closure during LVF pacing (P = 0.0268) and RVA pacing (P = 0.0197) as compared to BiV pacing.Conclusions
Findings suggest that BiV pacing improves cardiac output and systolic performance versus RVA pacing. This improvement however, is not reflected in tissue Doppler indices of synchronization and systolic performance. 相似文献94.
95.
Fontenelle JP Powell CC Hill AE Radecki SV Lappin MR 《Journal of Feline Medicine and Surgery》2008,10(1):41-46
Bartonella henselae has been implicated as a causative agent of chronic uveitis in people and in some cats. The objective of this study was to determine whether Bartonella species seroprevalence or titer magnitude varies among cats with uveitis, cats without ocular diseases recorded and healthy cats, while controlling for age and risk of flea exposure based on state of residence. There was no difference in seroprevalence rates or titer magnitude between cats with uveitis and cats with non-ocular diseases. Healthy cats were more likely to be seropositive for Bartonella species than cats with uveitis. The median Bartonella species titer was 1:64 for all groups, although healthy cats were more likely to have higher titers than cats with uveitis and cats with non-ocular disease. The results suggest that serum antibody tests alone cannot be used to document clinical uveitis associated with Bartonella species infection. 相似文献
96.
L. Shen A.H. Estrada E. Côté M.A. Powell B. Winter K. Lamb 《Journal of Veterinary Cardiology》2017,19(2):144-152
Introduction
To determine the relationship between aortoseptal angle (AoSA) and the short- and long-term systolic pressure gradient (PG) reduction following combined cutting and high-pressure balloon valvuloplasty (CB/HPBV) in dogs with severe subaortic stenosis.Animals
Retrospective study of 22 client-owned dogs of various breeds with severe subaortic stenosis (mean left ventricular to aortic PG = 143 mmHg; range = 80–322 mmHg) that underwent CB/HPBV.Materials and methods
Initial angiographic and left apical and right-sided parasternal long-axis view echocardiographic video loops were used for measuring the angle between the plane of the interventricular septum and the longitudinal axis of the ascending aorta. The PG reduction ratio immediately after CB/HPBV and 6 and 12 months later were compared with AoSA.Results
Weak correlations were observed for all instances of PG reduction ratio and AoSA type. Significantly greater mean differences of PG reduction ratio were observed for angles >160° than for angles <160° at 24 h (>160° mean: 54.45, standard error [SE]: ±3.8; <160° mean: 39.88, SE: ±2.09), 6 months (>160° mean: 57.73, SE: ±10.9; <160° mean: 28.22, SE: ±3.42), and 12 months (>160° mean: 76.11, SE: ±17.5; <160° mean: 27.61, SE: ±6.44; p=0.003).Conclusions
Dogs with AoSA >160° on right-sided parasternal long-axis view echocardiograms responded with a greater PG reduction following CB/HPBV than did dogs with AoSA <160°. This suggests that AoSA is associated with long-term outcomes of CB/HPBV, and measurement could help in the evaluation of dogs that are candidates for CB/HPBV. 相似文献97.
Elaine C Fitches Howard A Bell Michelle E Powell Emma Back Chiara Sargiotti Robert J Weaver John A Gatehouse 《Pest management science》2010,66(1):74-83
BACKGROUND: The toxicity of a fusion protein, ButalT/GNA, comprising a venom toxin (ButaIT) derived from the red scorpion, Mesobuthus tamulus (F.), and Galanthus nivalis agglutinin (GNA), was evaluated under laboratory conditions against several pest insects. Insecticidal activity was compared with SFI1/GNA, a fusion comprising a venom toxin (SFI1) derived from the European spider Segestria florentina (Rossi) and GNA, which has been previously demonstrated to be effective against lepidopteran and hemipteran pests, and to GNA itself. RESULTS: Injection assays demonstrated that both fusion proteins were toxic to lepidopteran larvae, dipteran adults, coleopteran adults and larvae and dictyopteran nymphs. ButalT/GNA was more toxic than SFI1/GNA in all cases. GNA itself made a minor contribution to toxicity. Oral toxicity of ButalT/GNA towards lepidopteran pests was confirmed against neonate Spodoptera littoralis (Boisd.), where incorporation at 2% dietary protein resulted in 50% mortality and > 85% reduction in growth compared with controls. ButaIT/GNA was orally toxic to Musca domestica L. adults, causing 75% mortality at 1 mg mL?1 in aqueous diets and, at 2 mg g?1 it was orally toxic to Tribolium castaneum (Herbst.), causing 60% mortality and a 90% reduction in growth. CONCLUSIONS: Toxicity of the ButaIT/GNA recombinant fusion protein towards a range of insect pests from different orders was demonstrated by injection bioassays. Feeding bioassays demonstrated the potential use of the ButaIT/GNA fusion protein as an orally active insecticide against lepidopteran, dipteran and coleopteran pests. These experiments provide further evidence that the development of fusion protein technology for the generation of new, biorational, anti‐insect molecules holds significant promise. © Crown Copyright 2009. Reproduced with permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd. 相似文献
98.
LOYD E. Powell CHARLOTT Pratt 《The Journal of Horticultural Science and Biotechnology》2013,88(4):331-348
Growth substances extracted from the ovules of developing fruits of July Queen, Halehaven and Fall Late peaches–respectively early, midseason and late-maturing cultivars–were studied. Whole and fractionated extracts were bioassayed, and the growth of the fruit and the development of the seed were examined.Determination of “total” growth-promoting substances during the development of the fruits resulted in concentration curves that were generally similar from year to year. The seeds of each cultivar, regardless of its season of maturation, produced a first flush of growth substances that seemed to be correlated with either nucellus or endosperm development. The second and major growth substance peak came at the time of rapid embryo growth and maximum endosperm development. At this time fruits of July Queen ripened and abscissed. A third flush of growth substance was detected at the same time in Halehaven and Fall Late seeds, at which time the embryo was essentially complete. The mature fruits of Halehaven then abscissed, but Fall Late fruits remained on the tree for another three or four weeks before maturation and abscission. It was concluded that the concentration of seed growth substances as measured here was not related to the final-flush of growth of peach fruits, or to the abscission of mature fruits.In dissected ovules of Halehaven peaches the endosperm was the most concentrated source of total growth substances on a dry weight basis but, because of its small size, it contributed less of them on a per-seed basis than did the the integuments at first, and later the embryo. The nucellus was a minor source of growth substances, both on a concentration and on a per-ovule basis. Apparently, the total growth substances that constituted the second and major auxin peak in Halehaven peach ovules came mostly from the integuments, endosperm and embryo, whereas the third peak could be attributed almost entirely to substances from the embryo. These studies of individual ovule tissues were made after that period of development during which the first growth substance peak made its appearance.Studies of growth substances in the flesh of developing peach fruits revealed only trace amounts with no consistent pattern, although there is some evidence that a true picture may not have been obtained because of interference by inhibitors.Silica gel partition column chromatography showed the presence of several growth-promoting substances which changed qualitatively and quantitatively during the growing season. One of these was probably indole-3- acetic acid, its identification being based primarily on studies by gas chromatography and spectrophotofluorometry. 相似文献
99.
A. H. Marshall T. A. Williams M. T. Abberton T. P. T. Michaelson-Yeates P. Olyott H. G. Powell 《Grass and Forage Science》2004,59(1):91-99
Interspecific hybrids between white clover (Trifolium repens L.) and Caucasian clover (Trifolium ambiguum M. Bieb.) have been developed to introgress the rhizomatous growth habit into white clover, to increase persistence and drought tolerance. The forage quality of T. repens, T. ambiguum and the backcross 1 (BC1) and backcross 2 (BC2) hybrids and companion grass, when grown in mixtures with an intermediate perennial ryegrass (Lolium perenne L.) under a cutting‐only management, was measured. In vitro dry‐matter digestibility (DMD), water‐soluble carbohydrate (WSC) and crude protein (CP) concentrations of the legume and grass fractions were measured throughout the growing season over three harvest years. Trifolium repens had a lower WSC but a higher CP concentration than the perennial ryegrass companion in all harvest years and at all cuts. The legume fractions from the BC1 and BC2 hybrid plots had a higher WSC and a lower CP concentration but an in vitro DMD value comparable with white clover throughout the growing season and in each harvest year. The grass fractions from the mixtures with the backcross hybrids had a higher WSC and a lower CP concentration than the grass fraction from the T. repens plots, in all harvest years and throughout the growing season. No difference in in vitro DMD between parental species and backcross hybrids was observed. The implications of these results for the development of these hybrids and animal performance are discussed. 相似文献
100.