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排序方式: 共有410条查询结果,搜索用时 15 毫秒
401.
OBJECTIVE: To analyze a centrifugation-based, point-of-care device that concentrates canine platelets and bone marrow-derived cells. ANIMALS: 19 adult sexually intact dogs. PROCEDURES: Anticoagulated peripheral blood (60 mL) and 60 mL of anticoagulated bone marrow aspirate (BMA) were concentrated by centrifugation with the centrifugation-based, point-of-care device to form a platelet and a bone marrow concentrate (BMC) from 11 dogs. Blood samples were analyzed on the basis of hemograms, platelet count, and PCV. The BMA and BMC were analyzed to determine PCV, total nucleated cell count, RBC count, and differential cell counts. The BMC stromal cells were cultured in an osteoinductive medium. Eight additional dogs were used to compare the BMC yield with that in which heparin was infused into the bone marrow before aspiration. RESULTS: The centrifugation-based, point-of-care device concentrated platelets by 6-fold over baseline (median recovery, 63.1%) with a median of 1,336 x 10(3) platelets/microL in the 7-mL concentrate. The nucleated cells in BMCs increased 7-fold (median recovery, 42.9%) with a median of 720 x 10(3) cells/microL in the 4-mL concentrate. The myeloid nucleated cells and mononuclear cells increased significantly in BMCs with a significant decrease in PCV, compared with that of BMAs. Stromal cell cultures expressed an osteoblastic phenotype in culture. Infusion of heparin into the bone marrow eliminated clot formation and created less variation in the yield (median recovery, 61.9%). CONCLUSIONS AND CLINICAL RELEVANCE: Bone marrow-derived cell and platelet-rich concentrates may form bone if delivered in an engineered graft, thus decreasing the need for cancellous bone grafts.  相似文献   
402.
Mao WL  Mao HK  Meng Y  Eng PJ  Hu MY  Chow P  Cai YQ  Shu J  Hemley RJ 《Science (New York, N.Y.)》2006,314(5799):636-638
When subjected to high pressure and extensive x-radiation, water (H2O) molecules cleaved, forming O-O and H-H bonds. The oxygen (O) and hydrogen (H) framework in ice VII was converted into a molecular alloy of O2 and H2. X-ray diffraction, x-ray Raman scattering, and optical Raman spectroscopy demonstrated that this crystalline solid differs from previously known phases. It remained stable with respect to variations in pressure, temperature, and further x-ray and laser exposure, thus opening new possibilities for studying molecular interactions in the hydrogen-oxygen binary system.  相似文献   
403.
In spite of the growing evidence showing the occurrence of nocturnal water exchange measured by stomatal conductance (SCnight, related to stomatal openness) and transpiration (TRnight, related to water losses) in different crops, how those processes are affected by soil water availability is still unknown. A preliminary study was conducted to test the occurrence of TRnight and SCnight (assessed in two moments) in two potato cultivars (UNICA and Sarnav), subjected to a long-term water restriction. The overall TRnight average were 9.0 ± 0.6 and 5.4 ± 2.6% for total daily transpiration under well-watered and water restricted conditions, respectively. Cultivar differences in early night and predawn SCnight and TRnight were more evident under non-restricted water conditions. Tuber yield was linearly correlated with TRnight and predawn and early-night SCnight. These preliminary findings emphasize the need for future research to corroborate the detection of TRnight and SCnight under water restrictions in potato, addressing the functional implications of these traits and the usefulness of SCnight for screening large sets of genotypes for potato breeding.  相似文献   
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The infectious salmon anaemia virus (ISAV) is capable of causing a significant disease in Atlantic salmon, which has resulted in considerable financial losses for salmon farmers around the world. Since the first detection of ISAV in Canada in 1996, it has been a high priority for aquatic animal health management and surveillance programmes have led to the identification of many genetically distinct ISAV isolates of variable virulence. In this study, we evaluated the virulence of three ISAV isolates detected in Atlantic Canada in 2012 by doing in vivo‐controlled disease challenges with two sources of Atlantic salmon. We measured viral loads in fish tissues during the course of infection. Sequences of the full viral RNA genomes of these three ISAV isolates were obtained and compared to a high‐virulence and previously characterized isolate detected in the Bay of Fundy in 2004, as well as a newly identified ISAV NA‐HPR0 isolate. All three ISAV isolates studied were shown to be of low to mid‐virulence with fish from source A having a lower mortality rate than fish from source B. Viral load estimation using an RT‐qPCR assay targeting viral segment 8 showed a high degree of similarity between tissues. Through genomic comparison, we identified various amino acid substitutions unique to some isolates, including a stop codon in the segment 8 ORF2 not previously reported in ISAV, present in the isolate with the lowest observed virulence.  相似文献   
406.
In this essay I explore the economic, social, environmental and cultural changes taking place in Bolsena, Italy, where agricultural livelihoods have rapidly diminished in the last two decades. I examine how gender dynamics have shifted with the changing values and livelihoods of Bolsena through three women’s narratives detailing their gendered experiences of environment, community and self. I reflect on these changes with Sabrina, who is engaged in a feminist community-based organization; Anna, who is running an alternative wine bar; and Isabella, a jeweler, who is engaged in ecofeminist practices. My analysis is based on concepts developed by feminist political ecology: specifically, the theory of rooted networks from Dianne Rocheleau, Donna Haraway’s concept of naturecultures (and the work of J. K. Gibson-Graham on new economic imaginaries emerging from the politics of place. I aim to think with, reflect upon and provoke from the “otherwise”, taking into account the lived relations entwining nature and gender. My article looks at the interconnections of gender, environment and livelihoods, attentive to the daily needs, embodied interactions and labours of these three women as part of a reappropriation, reconstruction and reinvention of Bolsena’s lifeworld. By listening to the stories of their everyday lives and struggles, I show the dynamic potential of the politics of place and the efforts to build diverse economies and more ethical economic and ecological relationships based on gender-aware subjectivities and values.  相似文献   
407.
Wild relatives of tomato possess effective means to deal with several pests, among which are a variety of insects. Here we studied the presence of resistance components against Trialeurodes vaporariorum, Myzus persicae, Frankliniella occidentalis, and Spodoptera exigua in the Lycopersicon group of Solanum section Lycopersicon by means of bioassays and comprehensive metabolite profiling. Broad spectrum resistance was found in Solanum galapagense and a few accessions of S. pimpinellifolium. Resistance to the sap sucking insects may be based on the same mechanism, but different from the caterpillar resistance. Large and highly significant differences in the leaf metabolomes were found between S. galapagense, containing type IV trichomes, and its closest relative S. cheesmaniae, which lacks type IV trichomes. The most evident differences were the relatively high levels of different methylated forms of the flavonoid myricetin and many acyl sucrose structures in S. galapagense. Possible candidate genes regulating the production of these compounds were identified in the Wf-1 QTL region of S. galapagense, which was previously shown to confer resistance to the whitefly B. tabaci. The broad spectrum insect resistance identified in S. galapagense will be very useful to increase resistance in cultivated tomato.  相似文献   
408.
The present study was aimed at developing preliminary reference values for foliar tissue for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) for `Valencia´ orange in Venezuela, using the Compositional Nutrient Diagnosis system (CND). References values were derived from a database comprising the nutrients concentrations and the yields of `Valencia´ orange trees (Citrus sinensis L. Osbeck) grafted on two different rootstocks, viz., Volkamer lemon (Citrus volkameriana Pasq.), and Cleopatra tangerine (Citrus reshni, Hort. ex. Tan). Cutoff values separating high- and low-yield sub-samples were estimated through modeling the cumulative variance ratio function versus yield relationships with the Boltzmann equation. For macronutrients, the norms developed were dependent upon the inclusion of the micronutrients concentrations in the calculations, and on the rootstocks. Care must thus be exercised, since nutrient indexes, and thus nutritional diagnosis, are based upon proper selection of such values.  相似文献   
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410.
Oat hull fiber is an insoluble source of dietary fiber, derived from the outermost layer of the oat grain. The effect of oat hull fiber on colonic function and serum lipids was investigated by conducting a controlled study on 10 healthy males, aged 20–37, who ate, for two three-week periods, a controlled low fiber diet (13.1 g of nonstarch polysaccharide [NSP]/day), and the same diet with 25 g of oat hull fiber per day incorporated into foods, providing 17 g of NSP/day. Fecal weight increased from 113 ± 10.4 to 155 ± 10.8 g/day (P < 0.001) with no change in transit time or serum lipids. Fermentation of oat hull fiber was studied by analysis of feces for NSP. Excretion of NSP increased from 2.0 g/day excreted to 19.7 g/day, indicating that no degradation had occurred. Oat hull fiber is therefore resistant to fermentation in the human colon, has no effect on serum lipids, and provides no energy to the body  相似文献   
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