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The underlying pathophysiological triggers for equine acute laminitis are unknown, although digital vasoconstriction, ischaemia, hypoxia and reperfusion injury may be involved. The contractile responses of isolated equine digital arteries (EDAs), harvested from the hindlimbs of normal horses postmortem at an abattoir, were studied acutely (up to 3 h) under hyperoxic (95% oxygen, 5% CO2) and hypoxic (95% nitrogen, 5% CO2) conditions in organ baths. Phenylephrine (PHE; 10?6 m ), 5‐hydroxytryptamine (5‐HT; 10?7 m ) and high potassium (K+; 118 mm ) caused contraction in EDAs which was significantly (P < 0.0001) enhanced under hypoxic conditions. In contrast, contraction stimulated by 9,11‐dideoxy‐9α,11α‐epoxymethanoprostaglandin F (U44069; 3 × 10?8 m ) was not significantly enhanced by hypoxia (P = 0.75). Hypoxia‐enhanced contraction in response to K+ was greater (P < 0.03) in vessels with a functional endothelium than in vessels in which the endothelium was removed by rubbing. Fasudil (10?6 to 10?5 m ), a Rho kinase inhibitor, and apocynin (10?3 to 3 × 10?3 m ), an NADPH oxidase inhibitor, significantly (P 0.05) inhibited hypoxia‐enhanced contraction in response to PHE and 5‐HT. In conclusion, hypoxia‐enhanced contraction occurred in EDAs. This appears to be partially mediated by reactive oxygen species produced by NAPDH oxidase, which activate Rho kinase to increase calcium sensitisation and enhance smooth muscle contraction.  相似文献   
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Lipopolysaccharide (LPS) can activate equine platelets directly or indirectly, via leukocyte-derived platelet activating factor (PAF). Thromboxane (Tx) production by LPS-stimulated equine platelets requires p38 MAPK and this kinase has been suggested as a therapeutic target in endotoxaemia. The present study has utilised selective inhibitors to investigate the role of p38 MAPK and two other kinases, phosphatidylinositol-3 kinase (PI3K) and protein kinase C (PKC), in regulating PAF-induced Tx production, aggregation and 5-HT release in equine platelets, and the modification of these responses by LPS. LPS enhanced PAF-induced 5-HT release, an effect that was reduced by the p38 MAPK inhibitor, SB203580 (60 ± 8% reduction; n  = 6). SB203580 did not affect responses to PAF alone; whereas inhibition of PKC reduced PAF-induced 5-HT release, Tx production and aggregation (maximal inhibition by the PKCδ inhibitor, rottlerin: 69 ± 13%, 63 ± 14% and 97 ± 1%, respectively; n  = 6). Wortmannin and LY249002, which inhibit PI3K, also caused significant inhibition of PAF-induced aggregation (maximal inhibition 78 ± 3% and 88 ± 2%, respectively; n  = 6). These data suggest that inhibition of platelet p38 MAPK may be of benefit in equine endotoxaemia by counteracting some of the effects of LPS. However, detrimental effects of platelet activation mediated by PAF and not enhanced by LPS are unlikely to be markedly affected.  相似文献   
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Abstract. Severe melanotic liver and visceral fibroses in bluegill associated with infections of plerocercoids of Proteocephalus sp. and metacercariae of the digenean Posthodiplostomum minimum , were studied by light and transmission electron microscopy. Fibrosis was most evident in bluegill carrying heavy worm burdens. Tubular and multilocular melanotic and non-melanotic cysts were formed of concentric layers of non-cellular eosinophilic connective tissue surrounding central spaces containing basophilic material. Moribund and deteriorating plerocercoids and metacercariae were surrounded by, and sometimes invested with, fibrous tissue. Living plerocercoids in the liver were surrounded by necrotic and compressed hepatocyte zones. Fibro-blasts, epithelioid cells and eosinophilic granulocytes were common in compressed cell zones. Intrahepatic fibrotic cysts were surrounded by granulomatous zones. Parenchyma in fibrotic livers showed increased numbers of macrophages, melano-macrophage centres and engorged blood vessels with thickened walls. Histochemical tests for lipofuscin and haemosiderin were strongly positive in melanotic liver tissue. Ultrastructural changes in hepatocytes adjacent to fibrotic cysts and epithelioid zones included intranuclear lipid and glycogen inclusions, chromatin alterations and mitochrondrial degeneration. Bile canaliculi, sinusoids and perisinusoidal spaces showed reduced micro villarsurfacesand a decrease in luminar diameter. Degenerating hepatocytes contained phagolysosomes and myelin bodies.  相似文献   
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Spatial variability in exponential mean soil temperature for a full year in a newly planted forest in northern England was examined using the sucrose inversion method of temperature measurement. The exponential mean temperature decreased significantly with soil depth (P < 0.001). The rate of this decrease varied significantly between different areas of the forest with slightly different soil profiles (0.001 < P < 0.01). Exponential means for 30–50cm depth in the forest and comparable arithmetic means for the nearest meteorological stations were similar. Exponential mean temperatures at 5 cm soil depth were, on average, 1.5° higher in the ridges than in the adjacent flat areas (P < 0.001). The exponential mean for the flat areas was, on average, 0.3° higher to the south-west of the ridge than to the north-east (0.001 < P < 0.01). It was also 0.9°C lower than the mean at 5 cm depth in the neighbouring rides (0.001 < P < 0.01).  相似文献   
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Forty strains of Staphylococci from infections of dogs and cats were characterized with respect to their coagulase and thermonuclease activities, and 19 strains for their fermentation of mannitol anaerobically. Thermonuclease correlated well with tube coagulase activity but there was a poor correlation between these two characters, the ability to ferment mannitol anaerobically, and the presence of bound coagulase. Fifty percent of the organisms were resistant to penicillin due to the presence of β-lactamase (penicillinase). There was a strict correlation between detection of β-lactamase by the disc diffusion and the slide penicillinase tests. Antibiotics to which organisms were resistant also were bacitracin (52·5%), lincomycin (20%), streptomycin (17·5%), tetracyclines (12·5%) and chloramphenicol (7·5%).  相似文献   
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