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Query: UMLS:C0220723 (PCA)
 4,687 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Here we studied the involvement of PCA-2, a low-virulent strain of Candida albicans known to act as a potent stimulating agent in the development of cryptococcal meningoencephalitis. To this purpose, mice received saline or PCA-2 intracerebrally 7 days before lethal local challenge with Cryptococcus neoformans. We found that, following C. neoformans challenge, PCA-2-treated but not saline-treated mice exhibited (a) delayed brain colonization, (b) enhanced median survival times, (c) massive local immune reaction consisting of abundant astrocytes, microglial and inflammatory cells, and (d) a peculiar trend of cytokine gene expression, including high steady-state levels of interleukin (IL)-1 beta and tumor necrosis factor alpha transcripts, fluctuating levels of interferon gamma and inducible nitric oxide synthase mRNA and lately detectable IL-6 gene expression. PCA-2-mediated immunostimulating properties were partially impaired by aminoguanidine or pentoxifylline treatment, further strengthening the conclusion that soluble mediators, including proinflammatory cytokines and nitric oxide, are important defense elements against cryptococcal meningoencephalitis.
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PMID:A low virulent strain of Candida albicans enhances brain anticryptococcal defenses: characterization of the local immune reaction by RT-PCR and histochemical analysis. 935 45

Does effective instruction, which changes students' knowledge and possibly alters their cognitive functions, also affect the dimensionality of an achievement test? This question was examined by the parameterization of kinesiology test items (n = 42) with a Rasch dichotomous model, followed by an investigation of dimensionality in a pre- and post-test quasi-experimental study design. College students (n = 108) provided responses to kinesiology achievement test items. Then the stability of item difficulties, gender differences, and the interaction of item content categories with dimensionality were examined. In addition, a PCA/t-test protocol was implemented to examine dimensionality threats from the item residuals. Internal construct validity was investigated by regressing item content components on calibrated item difficulties. Measurement model item residuals were also investigated with statistical decomposition methods. In general, the results showed significant student achievement between pre and post testing, and dimensionality disturbances were relatively minor. The amount of unexpected item "shift" in an un-equated measurement dimension between pre and post testing was less than ten percent of the total items and largely concentrated among several unrelated items. An unexpected finding was a residual cluster consisting of several items testing related technical content. Complicating interpretation, these items tended to appear near the end of the test, which implicates test position as a threat to measurement equivalence. In general, the results across several methods did not tend to identify common threats and instead pointed to multiple sources of threats with varying degree of prominence. These results suggest conventional approaches to measurement equivalence that emphasize expedient overall procedures such as DIF, IRT, and factor analysis are probably capturing isolated sources of variability. Their implementation probably improves measurement equivalence but with substantial residual sources undetected.
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PMID:Does Instruction Affect the Underlying Dimensionality of a Kinesiology Test? 2800 88