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c. keys, s. kemper and p. keim. 2005.Evaluation of theEscherichia coligenome for variable number tandem repeat (VNTR) loci in order to provide a subtyping tool with greater discrimination and more efficient capacity.Twenty-nine putative VNTR loci were identified from theE. coligenomic sequence. Their variability was validated by characterizing the number of repeats at each locus in a set of 56E. coliO157:H7/HN and O55:H7 isolates. An optimized multiplex assay system was developed to facility high capacity analysis. Locus diversity values ranged from 0·23 to 0·95 while the number of alleles ranged from two to 29. This multiple-locus VNTR analysis (MLVA) data was used to describe genetic relationships among these isolates and was compared with PFGE (pulse field gel electrophoresis) data from a subset of the same strains. Genetic similarity values were highly correlated between the two approaches, through MLVA was capable of discrimination amongst closely related isolates when PFGE similar values were equal to 1·0.Highly variable VNTR loci exist in theE. coliO157:H7 genome and are excellent estimators of genetic relationships, in particular for closely related isolates.Escherichia coliO157:H7 MLVA offers a complimentary analysis to the more traditional PFGE approach. Application of MLVA to an outbreak cluster could generate superior molecular epidemiology and result in a more effective public health response. [ABSTRACT FROM AUTHOR]

The effects of a memory load on syntactic processing by younger and older adults were examined. Participants were asked to remember a noun phrase (NP) memory load while they read sentences varying in syntactic complexity. Two types of NPs were used as memory loads: proper names or definite descriptions referring to occupations or roles. The NPs used in the sentence and memory load either matched (e.g., all proper names or all occupations), or they mismatched. Participants read complex sentences more slowly than they did simpler sentences; for young adults, this complexity effect was exacerbated when memory interference was generated by matching NPs in the sentence and memory load, whereas for older adults, memory-load interference did not vary with sentence complexity or memory-load matching. These results suggest that a general reduction in older adults' processing capacity was produced by the memory load, whereas the matching memory loads and sentence NPs produced a more specific form of interference that affected young adults' online processing. [ABSTRACT FROM AUTHOR]

This study compared sentence acceptability judgments from young and healthy older adults and older adults with dementia due to probable Alzheimer's disease. Two types of sentences were contrasted: one type involved contrasts among verb alternations in which semantic distinctions between verbs regulate the acceptability of phrase structure variations; the second type involved contrasts among directional transformations in which constraints on the movement of noun phrases determine the linear order of main and embedded clauses. The primary findings were that metalinguistic judgments by healthy older adults as well as those with probable Alzheimer's reflected processing demands on working memory. In addition, metalinguistic judgments by adults with probable Alzheimer's reflected the breakdown of semantic information about verbs. [ABSTRACT FROM AUTHOR]