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排序方式: 共有103条查询结果,搜索用时 15 毫秒
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This experiment was done to study the effects of dietary soybean meal (SBM) and inulin (a prebiotic) on the capacity for digestive hydrolysis and amino acid absorption by Atlantic salmon, and how a dietary supplement of the broad-spectrum antibiotic oxytetracycline (OTC) modulated these responses. A control diet (FM) was made from fish meal, fish oil and extruded wheat. Two similar diets were made with 250 g soybean meal (SBM) or 75 g inulin kg− 1. Each diet was made with or without a supplement of 3 g OTC kg− 1. All six diets contained yttrium oxide for estimation of apparent nutrient absorption. Each diet was fed to two groups of 172 g salmon kept in 1 m2 tanks with 9 °C saltwater for 3 weeks. Intestinal organs were then sampled and weighed. Gastrointestinal tracts (GIT) were sectioned for analyses of brush border alkaline phosphatase (ALP) and leucine aminopeptidase (LAP) activities. Tissue from the distal intestine (DI) was also fixed for histological examination. Digesta from the different sections were freeze dried for estimation of trypsin and amylase activities, and of apparent absorption of amino acids (AA), nitrogen (N), and sulphur (S). About 85% of the trypsin activity, 70% of the amylase activity, 85% of the ALP activity, and 82% of the LAP activity were found in the proximal (PI) and mid (MI) intestine of fish with functional DI, and the absorption of AA, N, and S was quantitatively completed in the MI. Dietary OTC resulted in lower relative liver weight, but apart from increased ALP and LAP activities in DI when feeding OTC in combination with inulin, OTC did not modify the responses to dietary SBM or inulin. Dietary SBM resulted in lower relative liver weight, and induced pathomorphological changes in the DI mucosa, thus lower the ALP and LAP activities in the DI. SBM also stimulated absorption of AA, N, and S in the PI, but at the same time increased the activities of trypsin and amylase in the DI, indicating reduced re-absorption and increased faecal losses of these endogenous enzymes. Dietary inulin did not damage the DI, and stimulated intestinal growth and higher relative mass of the GIT. Inulin without OTC did not affect the hydrolytic and absorptive capacity of the salmon GIT.  相似文献   
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Nanominerals, mineral nanoparticles, and Earth systems   总被引:4,自引:0,他引:4  
Minerals are more complex than previously thought because of the discovery that their chemical properties vary as a function of particle size when smaller, in at least one dimension, than a few nanometers, to perhaps as much as several tens of nanometers. These variations are most likely due, at least in part, to differences in surface and near-surface atomic structure, as well as crystal shape and surface topography as a function of size in this smallest of size regimes. It has now been established that these variations may make a difference in important geochemical and biogeochemical reactions and kinetics. This recognition is broadening and enriching our view of how minerals influence the hydrosphere, pedosphere, biosphere, and atmosphere.  相似文献   
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Waterpower     
Penn TZ 《Science (New York, N.Y.)》1980,208(4451):1451-1452
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Epizootic ulcerative syndrome was diagnosed, and the presence of Aphanomyces invadans confirmed, from an outbreak of clinical disease in wild‐caught bony bream (Nematalosa erebi) from the Darling River near Bourke, in New South Wales, Australia, during 2008. This confirms a significant extension of the agent beyond its historical range.  相似文献   
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ObjectiveTo investigate the contribution of K+ channels on peripheral antinociception induced by ketamine.Study designProspective experimental study.Animals110 male Wistar rats weighing 160–200 g.MethodsThe paw pressure required to elicit limb flexion was designated as the nociceptive threshold. Hyperalgesia was induced by intraplantar injection of prostaglandin E2. All drugs were administered locally into the right hind paw of rats. Ketamine was administered into the right hind paw 2 hours and 55 minutes after local injection of PGE2. Tetraethylammonium was administered 30 minutes prior to ketamine and the other K+ channel blockers, glibenclamide, dequalinium and paxilline, were administered 5 minutes prior to ketamine.ResultsProstaglandin E2 (2 μg per paw) induced hyperalgesia. Ketamine (10, 20, 40 and 80 μg per paw) elicited a local peripheral antinociceptive effect that was antagonized by a specific blocker of ATP‐sensitive K+ channels, glibenclamide (20, 40 and 80 μg per paw). In another experiment, the non‐selective voltage‐dependent K+ channel blocker tetraethylammonium (30 μg per paw) and small and large conductance blockers of Ca2+‐activated K+ channels, dequalinium (50 μg per paw) and paxilline (20 μg per paw), were ineffective at blocking the effect of a local ketamine injection.Conclusions and clinical relevanceAnalysis of these results provides evidence that ketamine, may in part, induce peripheral antinociceptive effects by ATP‐sensitive K+ channel pathway activation.  相似文献   
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Abstract

CASE HISTORY: A group of 545 pregnant rising 2-year-old Coopdale ewes on a Southland sheep farm were grazed over winter on a fodder beet (Beta vulgaris) crop. Subsequently, 45 out of approximately 750 lambs were born with a variety of skeletal deformities, including shortened limbs, varus and valgus angular limb deformities, palmar grade stance and cranial bowing of the carpus. Analysis of the crop showed the fodder beet contained a low percentage of phosphorus. In addition, 60 out of 460 rising 2-year-old ewes that had been grazed on the fodder beet crop as 1-year-olds had incisor abnormalities and malocclusion.

PATHOLOGICAL FINDINGS: Two affected lambs (1-day-old and 3-days-old) with representative clinical signs examined postmortem were found to have markedly enlarged costochondral junctions, and noticeably enlarged long bone metaphyses. In addition, one lamb had a dense band of metaphyseal sclerosis beneath the physes of all long bones examined. Histopathological findings included small islands and columns of chondrocytes and eosinophilic cartilage matrix present in the metaphysis. Metaphyseal trabeculae were disorganised and often lined by accumulations of pale pink osteoid; similar pale pink osteoid was also present in the cortices. Unerupted molar teeth in the affected lambs lacked a layer of enamel, and the dentine was irregular with globular basophilia.

DIAGNOSIS: The gross and histopathological lesions were consistent with a diagnosis of rickets.

CLINICAL RELEVANCE: Nutritional congenital rickets has not been previously diagnosed in sheep, but is a recognised disease of human infants with vitamin D deficient mothers. The rickets in affected lambs was most likely associated with phosphorus deficiency as a result of the pregnant ewes grazing fodder beet during gestation. While vitamin D deficiency was not definitively ruled out in these cases, practitioners are alerted to the possible effects of feeding phosphorus-deficient fodder beet to ewes for long periods during gestation and to 1-year-old sheep during important growth periods.  相似文献   
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Four Missouri stalagmites yield consistent overlapping records of oxygen and carbon isotopic changes and provide a climate and vegetation history with submillennial resolution from 75 to 25 thousand years ago (ka). The thorium-230-dated records reveal that between 75 and 55 ka, the midcontinental climate oscillated on millennial time scales between cold and warm, and vegetation alternated among forest, savanna, and prairie. Temperatures were highest and prairie vegetation peaked between 59 and 55 ka. Climate cooled and forest replaced grassland at 55 ka, when global ice sheets began to build during the early part of Marine Oxygen Isotope Stage 3.  相似文献   
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