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61.
Glaser O 《Science (New York, N.Y.)》1918,48(1252):647-648
62.
Enhanced metabolism of Leishmania donovani amastigotes at acid pH: an adaptation for intracellular growth 总被引:11,自引:0,他引:11
Amastigotes (tissue forms) of Leishmania donovani isolated from infected hamster spleens carried out several physiological activities (respiration, catabolism of energy substrates, and incorporation of precursors into macromolecules) optimally at pH 4.0 to 5.5. All metabolic activities that were examined decreased sharply above the optimal pH. Promastigotes (culture forms), on the other hand, carried out the same metabolic activities optimally at or near neutral pH. This adaptation to an acid environment may account in part for the unusual ability of amastigotes to survive and multiply within the acidic environment of the phagolysosomes in vivo. 相似文献
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65.
Heather L. Priest Nita L. Irby Donald H. Schlafer Thomas J. Divers Bettina Wagner Amy L. Glaser Yung‐Fu Chang Mary C. Smith 《Veterinary ophthalmology》2012,15(6):398-405
Borrelia burgdorferi, the etiologic agent of Lyme disease is a tick born spirochetal infection. Clinical signs of Lyme borreliosis are uncommon in horses, but when present they are often vague and nonspecific. In horses, Lyme borreliosis has been implicated in musculoskeletal, neurological, reproductive, and ocular disorders, including uveitis, but definitive diagnosis can be challenging as the causative agent is rarely isolated and serologic tests can be unreliable and do not confirm active disease. Here, we report two cases of equine uveitis associated with B. burgdorferi based on the identification of spirochetes within ocular fluids and confirmed with PCR testing. The two cases illustrate some of the challenges encountered in the recognition and diagnosis of equine Lyme borreliosis. Although only one of many possible causes of equine uveitis, Lyme disease should be considered a differential diagnosis, especially in endemic areas. Given the possibility for false negative results of serum tests during uveitis associated with B. burgdorferi and the failure of such tests to confirm active infection, a combination of cytologic assessment, antibody, and/or PCR testing of ocular fluids may be worthwhile if the clinical suspicion for Lyme uveitis is high. 相似文献
66.
The calculation of a study's required sample size is one of the most important aspects of the validity of an epidemiological study. Logistic regression often is used in modelling in epidemiology. A simplified method to calculate the sample size for the multiple logistic-regression model was proposed by Hsieh et al. [Stat. Med. 17 (1998) 1623]. The approach for estimating the sample size is described and then applied in the planning of an epidemiological cross-sectional study of the associations of different risk factors with Toxoplasma infection among pregnant women. Although the method demands some additional information which is often difficult to obtain, it is a very useful tool in veterinary epidemiology. 相似文献
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Giuseppe Di Rauso Simeone Mireen Müller Christoph Felgentreu Bruno Glaser 《植物养料与土壤学杂志》2020,183(4):539-549
Background: Cover cropping appears as a useful land management practice with numerous benefits for ecosystem functions. Aim: The objectives of this study were to determine the effects of different winter cover crops on soil microbial biomass, activity, and community composition in intensively managed agriculture systems as function of cover crop diversity. Methods: For this purpose, an on‐farm experiment was conducted at a podzolized Stagnosol‐Cambisol during seven months growing oil radish as single cover crop and five different cover crop mixtures comprising 5 to 13 plant species. A fallow treatment was used as control. Phospholipid fatty acids were used to determine the soil microbial biomass and soil microbial community composition. Basal respiration of the soil microorganisms was measured as a proxy for microbial activity. Results: The results show that none of the cover crop mixture could increase soil organic carbon or total nitrogen content. Three cover crop mixtures and oil radish as single cover crop significantly increased soil microbial biomass by about 50% and all of the investigated cover crops significantly increased microbial respiration and metabolic quotient by 50–150%. Only highly diverse cover crop mixtures significantly increased individual microbial groups such as Gram‐positive and Gram‐negative bacteria, actinobacteria, and saprotropic and mycorrhizal fungi by about 20% compared to the control. However, the ratio of fungi to bacteria was not influenced by any of the cover crop mixtures under study. Conclusion: These findings corroborate that aboveground plant diversity is linked to belowground microbial diversity. 相似文献
69.
Jie Liu Hardy Schulz Susanne Brandl Herbert Miehtke Bernd Huwe Bruno Glaser 《植物养料与土壤学杂志》2012,175(5):698-707
Crop growth in sandy soils is usually limited by plant‐available nutrients and water contents. This study was conducted to determine whether these limiting factors could be improved through applications of compost and biochar. For this purpose, a maize (Zea mays L.) field trial was established at 1 ha area of a Dystric Cambisol in Brandenburg, NE Germany. Five treatments (control, compost, and three biochar‐compost mixtures with constant compost amount (32.5 Mg ha–1) and increasing biochar amount, ranging from 5–20 Mg ha–1) were compared. Analyses comprised total organic C (TOC), total N (TN), plant‐available nutrients, and volumetric soil water content for 4 months under field conditions during the growing season 2009. In addition, soil water‐retention characteristics were analyzed on undisturbed soil columns in the laboratory. Total organic‐C content could be increased by a factor of 2.5 from 0.8 to 2% (p < 0.01) at the highest biochar‐compost level compared with control while TN content only slightly increased. Plant‐available Ca, K, P, and Na contents increased by a factor of 2.2, 2.5, 1.2, and 2.8, respectively. With compost addition, the soil pH value significantly increased by up to 0.6 (p < 0.05) and plant‐available soil water retention increased by a factor of 2. Our results clearly demonstrated a synergistic positive effect of compost and biochar mixtures on soil organic‐matter content, nutrients levels, and water‐storage capacity of a sandy soil under field conditions. 相似文献
70.
Mireia Llorente Bruno Glaser María-Belén Turrión 《European Journal of Forest Research》2010,129(6):1143-1153
In the last century, many calcareous soils in Castilla León (northwestern Spain) have been transformed from natural Quercus ilex forest to cropped land. Reforestation with Pinus halepensis has been taking place during the past 40 years. In order to obtain a better understanding of how these disturbances affect
ecosystem functioning, we studied the quantity and quality of soil organic matter (SOM) in natural forest ecosystems, cropland
and Pinus plantations. Density fractionation combined with ultrasonic dispersion enables separation and study of SOM fractions:
free organic matter (OM), OM occluded into aggregates and OM stabilized in organo-mineral complexes, considered on the basis
of the type of physical protection provided. We separated SOM density fractions and determined the concentrations of C and
N, C/N ratios and the natural isotopic abundance (δ13C and δ15N values). Transformation of Quercus forest to cropland resulted in major losses of SOC and N, as expected. However, subsequent
reforestation with Pinus resulted in good recovery of the original SOC and soil N pools. This indicates the potential for
enhanced C storage in agricultural soils by their reversion to a forested state. Study of the density fractions and their
13C and 15N signatures enabled better understanding of the high stability of OM in calcareous soils, and analysis of δ13C variations throughout the profile also enabled identification of past C3/C4 vegetation change. Despite the different OC
contents of soils under different land use, OM stabilization mechanisms were not significantly different. In calcareous soils,
accumulation of SOC and N is mainly due to organo-mineral associations, resulting in physicochemical stabilization against
further decomposition. 相似文献