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排序方式: 共有152条查询结果,搜索用时 484 毫秒
1.
Effect of Age,Season, Body Condition,and Endocrine Status on Serum Free Cortisol Fraction and Insulin Concentration in Horses 下载免费PDF全文
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OBJECTIVE: To characterize age-associated changes in lymphocyte population subsets and immunoglobulin isotypes. ANIMALS: 30 healthy young light-breed horses (5 to 12 years old) and 30 healthy aged light-breed horses (> 20 years old). PROCEDURE: Lymphocyte subset populations were identified, using monoclonal antibodies to cell surface markers CD5, CD4, CD8, and IgG. Subset populations were quantitated by use of flow cytometric analysis of antibody-stained cells. Serum immunoglobulin concentration was determined using single radial immunodiffusion. RESULTS: Absolute cell counts of total lymphocytes, T cells, CD4+ and CD8+ T cells, and B cells were decreased in aged horses, compared with young horses. There was a significant decrease in the percentage of CD8+ cells and an increase in the CD4+-to-CD8+ cell ratio in the aged population, compared with young horses. However, serum concentration of IgG, IgG(T), IgM, or IgA did not differ with age. CONCLUSIONS AND CLINICAL RELEVANCE: In horses, total lymphocyte count and lymphocyte subset cell counts decrease with age. Age-matched control values are necessary for optimal evaluation of hematologic variables in aged horses. The decrease in lymphocyte subset cell counts in healthy aged horses mimics that seen in other species and may contribute to an age-associated decrease in immunocompetency. 相似文献
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The life history traits of 42 marine fish species were grouped according to the theoretical classifications of life history strategies. This provides a conceptual framework of management options, because life history strategies are the underlying determinants for population responses to climate and ocean changes, they can be used to classify typical population responses. When faced with providing management advice for species for which there is no information on absolute or relative biomass, such as newly exploited species, life history traits can be used to classify the species into a strategist grouping and the appropriate management options can be selected from the conceptual framework. 相似文献
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A full ophthalmic examination was performed on 40 Siberian husky dogs using direct and indirect ophthalmoscopy, gonloscopy and nasolacrimal cannulation. Eight (20%) of the dogs were found to have distichia, 10 (25%) had excessive medial caruncular hairs, 8 (20%) had absence, displacement, or narrowing of the nasolacrimal puncta, 2 (5%) had bilateral corneal crystalline opacities, and 2 (5%) had unilateral areas of lateral corneal lipidosis. Fifty percent of the dogs had some abnormality of the iridocorneal (drainage) angle. However, in only one of these was the deformity severe enough to require glaucoma prophylaxis. An association between blue iris colour and malformation of the iridocorneal angle was noted. 相似文献
8.
RP Andres T Bein M Dorogi S Feng JI Henderson CP Kubiak W Mahoney RG Osifchin R Reifenberger 《Science (New York, N.Y.)》1996,272(5266):1323-1325
Double-ended aryl dithiols [alpha,alpha'-xylyldithiol (XYL) and 4,4'-biphenyldithiol] formed self-assembled monolayers (SAMs) on gold(111) substrates and were used to tether nanometer-sized gold clusters deposited from a cluster beam. An ultrahigh-vacuum scanning tunneling microscope was used to image these nanostructures and to measure their current-voltage characteristics as a function of the separation between the probe tip and the metal cluster. At room temperature, when the tip was positioned over a cluster bonded to the XYL SAM, the current-voltage data showed "Coulomb staircase" behavior. These data are in good agreement with semiclassical predictions for correlated single-electron tunneling and permit estimation of the electrical resistance of a single XYL molecule (approximately18 ± 12 megohms). 相似文献
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In the bottlenose dolphin Tursiops truncatus, a massive retial complex is interposed between the systemic and cerebral circulations at the cervicothoracic level. Pressure measurements in the retial efferent arteries supplying the brain revealed relatively nonpulsatile pressure profiles. These measurements in the anesthetized dolphin demonstrate the pressure-damping effect of the retia mirabile. 相似文献
10.
Hyperkalemic periodic paralysis and the adult muscle sodium channel alpha-subunit gene 总被引:22,自引:0,他引:22
B Fontaine T S Khurana E P Hoffman G A Bruns J L Haines J A Trofatter M P Hanson J Rich H McFarlane D M Yasek 《Science (New York, N.Y.)》1990,250(4983):1000-1002
Hyperkalemic periodic paralysis (HYPP) is an autosomal dominant disorder characterized by episodes of muscle weakness due to depolarization of the muscle cell membrane associated with elevated serum potassium. Electrophysiological studies have implicated the adult muscle sodium channel. Here, portions of the adult muscle sodium channel alpha-subunit gene were cloned and mapped near the human growth hormone locus (GH1) on chromosome 17. In a large pedigree displaying HYPP with myotonia, these two loci showed tight linkage to the genetic defect with no recombinants detected. Thus, it is likely that the sodium channel alpha-subunit gene contains the HYPP mutation. 相似文献