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

Guinea-pigs produced both gamma1 and gamma2 antibodies against Escherichia coli K12, W3110/SM when they were injected intraperitoneally with a suspension of heat-killed bacteria without adjuvant twice a week for 12 weeks. The antibodies were separated by DEAE-cellulose chromatography. The gamma1 antibodies gave PCA reaction against soluble antigens prepared from sonicated E. coli, but the gamma2 antibodies did not. Both gamma1 and gamma2 antibodies induced complement-mediated bactericidal reaction against the homologous bacteria. In the case of gamma1 antibodies presensitization of bacteria with the antibodies before the addition of complement enhanced their bactericidal activity to a degree, EGTA inhibited the bactericidal activity of gamma2 antibodies, more than that of gamma1 antibodies. It is suggested that the gamma1 antibodies kill bacteria via the alternative pathway of complement activation, whilst the gamma2 antibodies exert their bactericidal activity mainly through the classical pathway.
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PMID:Immune bactericidal reactions by guinea-pig gamma1 and gamma2 antibodies. 81 78

The identification of translation initiation sites (TISs) constitutes an important aspect of sequence-based genome analysis. An erroneous TIS annotation can impair the identification of regulatory elements and N-terminal signal peptides, and also may flaw the determination of descent, for any particular gene. We have formulated a reference-free method to score the TIS annotation quality. The method is based on a comparison of the observed and expected distribution of all TISs in a particular genome given prior gene-calling. We have assessed the TIS annotations for all available NCBI RefSeq microbial genomes and found that approximately 87% is of appropriate quality, whereas 13% needs substantial improvement. We have analyzed a number of factors that could affect TIS annotation quality such as GC-content, taxonomy, the fraction of genes with a Shine-Dalgarno sequence and the year of publication. The analysis showed that only the first factor has a clear effect. We have then formulated a straightforward Principle Component Analysis-based TIS identification strategy to self-organize and score potential TISs. The strategy is independent of reference data and a priori calculations. A representative set of 277 genomes was subjected to the analysis and we found a clear increase in TIS annotation quality for the genomes with a low quality score. The PCA-based annotation was also compared with annotation with the current tool of reference, Prodigal. The comparison for the model genome of Escherichia coli K12 showed that both methods supplement each other and that prediction agreement can be used as an indicator of a correct TIS annotation. Importantly, the data suggest that the addition of a PCA-based strategy to a Prodigal prediction can be used to 'flag' TIS annotations for re-evaluation and in addition can be used to evaluate a given annotation in case a Prodigal annotation is lacking.
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PMID:A Novel Quality Measure and Correction Procedure for the Annotation of Microbial Translation Initiation Sites. 2620 19