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Strains Present (strain + present)
Selected AbstractsA comparative study of single-line and Rietveld strain,size evaluation procedures using MgO ceramicsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2002Suminar Pratapa Strain,size evaluations from diffraction line broadening for MgO ceramic materials have been compared using single-line integral-breadth and Rietveld procedures with the Voigt function. Diffraction data were measured by Bragg,Brentano X-ray diffractometry (XRD), without incident beam monochromatization, and neutron diffractometry (ND) to encompass near-surface and bulk effects, respectively. The specimens consisted of sets of MgO ceramics and MgO,Y2O3 ceramic composites sintered over a range of temperatures. An MgO ceramic sintered at 1723,K for 2,h exhibited slightly less XRD broadening than the standard LaB6 NIST 660 SRM, and was therefore selected to make instrument profile corrections for both XRD and ND data. It was found for both data types that: (a) sintering initially relieves residual strain present in the MgO powder used to sinter the ceramics and also promotes grain growth; (b) residual strain of the MgO ceramic minimizes as the sintering temperature increases, and then increases with further rise in the sintering temperature, presumably as a result of intragranular interactions associated with grain growth; and (c) introduction of the second phase (Y2O3) increases strain and inhibits crystal growth. The single-line and Rietveld methods gave similar strain values from both the XRD and ND data within the limits of experimental error, but there were substantial differences between the single-line and Rietveld size estimates determined with the XRD and ND data. [source] Absence of Borrelia burgdorferi DNA in cutaneous B-cell lymphomas from the United StatesJOURNAL OF CUTANEOUS PATHOLOGY, Issue 10 2001Gary S. Wood Background: An association between Borrelia burgdorferi and cutaneous B-cell lymphoma (CBCL) has been made in several European countries. The evidence in favor of such an association has recently been based on more definitive tests for the pathogenetic role of B. burgdorferi in CBCL, including positive cultures or polymerase chain reaction (PCR) amplification of borrelial DNA from lesional skin. However, there is only one report of B. burgdorferi in four North American cases of B-cell lymphoma. Methods: We retrieved 38 cases of primary and secondary CBCL from different geographic regions of the United States. Two separate techniques were used to detect borrelial DNA by PCR, a nested PCR method to amplify a B. burgdorferi -specific gene as well as a borrelial chromosomal Ly-1 clone amplification method. Southern blot hybridization was used for confirmation of the PCR results. Results: No B. burgdorferi -specific DNA was detected in any of the 38 CBCL cases, whereas detectable PCR products were obtained with our positive controls. Conclusions: Our findings, in light of previous studies, suggest that B. burgdorferi plays a minimal role in the development or pathogenesis of CBCL in the United States. The findings also suggest that the geographic variations in the clinical manifestations of B. burgdorferi are indeed real and may be secondary to the genetic and phenotypic differences between B. burgdorferi strains present in Europe and North America. [source] Recent advances in the biogeography and genecology of symbiotic Frankia and its host plantsPHYSIOLOGIA PLANTARUM, Issue 3 2007David R. Benson Molecular phylogenetic approaches have begun to outline the origin, distribution and diversity of actinorhizal partners. Geographic isolation of Frankia and its host plants resulting from shifting continents and dispersal patterns have apparently led to the development of Frankia genotypes with differing affinities for host genera, even within the same plant family. Actinorhizal plant genera of widespread global distribution tend to nodulate readily even outside their native ranges. These taxa may maintain infective Frankia populations of considerable diversity on a broad scale. Arid environments seem to have distinctive actinorhizal partnerships, with smaller and more specific sets of Frankia symbionts. This has led to the hypothesis that some host families have taxa that are evolving towards narrow strain specificity, perhaps because of drier habitats where fewer Frankia strains would be able to survive. Harsh conditions such as water-saturated soils near lakes, swamps or bogs that are typically acidic and low in oxygen may similarly lessen the diversity of Frankia strains present in the soil, perhaps limiting the pool of frankiae available for infection locally and, at a larger scale, for natural selection of symbiotic partnerships with host plants. Recent molecular ecological studies have also provided examples of Frankia strain sorting by soil environment within higher order cluster groupings of Frankia host specificity. Future frontiers for ecological research on Frankia and actinorhizal plants include the soil ecosystem and the genome of Frankia and its hosts. [source] Strain-Associated Variations in Abnormal PrP Trafficking of Sheep ScrapieBRAIN PATHOLOGY, Issue 1 2009FRC Path, MRCVS, Martin Jeffrey BVMS DVM Dip ECVP Abstract Prion diseases are associated with the accumulation of an abnormal form of the host-coded prion protein (PrP). It is postulated that different tertiary or quaternary structures of infectious PrP provide the information necessary to code for strain properties. We show here that different light microscopic types of abnormal PrP (PrPd) accumulation found in each of 10 sheep scrapie cases correspond ultrastructurally with abnormal endocytosis, increased endo-lysosomes, microfolding of plasma membranes, extracellular PrPd release and intercellular PrPd transfer of neurons and/or glia. The same accumulation patterns of PrPd and associated subcellular lesions were present in each of two scrapie strains present, but they were present in different proportions. The observations suggest that different trafficking pathways of PrPd are influenced by strain and cell type and that a single prion strain causes several PrPd,protein interactions at the cell membrane. These results imply that strains may contain or result in production of multiple isoforms of PrPd. [source] | ||||||||||