We investigated synaptic communication and plasticity in hippocampal slices from mice overexpressing mutated 695-amino-acid human amyloid precursor protein (APP695SWE), which show behavioral and histopathological abnormalities simulating Alzheimer's disease. Although aged APP transgenic mice exhibit normal fast synaptic transmission and short term plasticity, they are severely impaired in in-vitro and in-vivo long-term potentiation (LTP) in both the CA1 and dentate gyrus regions of the hippocampus. The LTP deficit was correlated with impaired performance in a spatial working memory task in aged transgenics. These deficits are accompanied by minimal or no loss of presynaptic or postsynaptic elementary structural elements in the hippocampus, suggesting that impairments in functional synaptic plasticity may underlie some of the cognitive deficits in these mice and, possibly, in Alzheimer's patients.

Background Drug-induced long QT syndrome (diLQTS) is an adverse drug effect that has an important impact on drug use, development, and regulation. Here, we tested the hypothesis that common variants in key genes controlling cardiac electrical properties modify the risk of diLQTS. Methods and Results In a case-control setting, we included 176 patients of European descent from North America and Europe with diLQTS, defined as documented torsades de pointes during treatment with a QT prolonging drug. Control samples were obtained from 207 patients of European ancestry who displayed <50 msec QT lengthening during initiation of therapy with a QT-prolonging drug, and 837 controls from the population based KORA study. Subjects were successfully genotyped at 1,424 single nucleotide polymorphisms (SNPs) in 18 candidate genes including 1,386 SNPs tagging common haplotype blocks, and 38 non-synonymous ion channel gene SNPs. For validation we used a set of cases (n=57) and population-based controls of European descent. The SNP KCNE1 D85N (rs1805128), known to modulate an important potassium current in the heart, predicted diLQTS with an odds ratio of 9.0 (95% confidence interval: 3.5–22.9). The variant allele was present in 8.6% of cases, 2.9% of drug-exposed controls, and 1.8% of population controls. In the validation cohort the variant allele was present in 3.5% of cases, and in 1.4% of controls. Conclusions This high-density candidate SNP approach identified a key potassium channel susceptibility allele that may be associated with the rare adverse drug reaction torsades de pointes.

Height is a classic complex trait with common variants in a growing list of genes known to contribute to the phenotype. Using a genecentric genotyping array targeted toward cardiovascular-related loci, comprising 49,320 SNPs across approximately 2000 loci, we evaluated the association of common and uncommon SNPs with adult height in 114,223 individuals from 47 studies and six ethnicities. A total of 64 loci contained a SNP associated with height at array-wide significance (p < 2.4 × 10(-6)), with 42 loci surpassing the conventional genome-wide significance threshold (p < 5 × 10(-8)). Common variants with minor allele frequencies greater than 5% were observed to be associated with height in 37 previously reported loci. In individuals of European ancestry, uncommon SNPs in IL11 and SMAD3, which would not be genotyped with the use of standard genome-wide genotyping arrays, were strongly associated with height (p < 3 × 10(-11)). Conditional analysis within associated regions revealed five additional variants associated with height independent of lead SNPs within the locus, suggesting allelic heterogeneity. Although underpowered to replicate findings from individuals of European ancestry, the direction of effect of associated variants was largely consistent in African American, South Asian, and Hispanic populations. Overall, we show that dense coverage of genes for uncommon SNPs, coupled with large-scale meta-analysis, can successfully identify additional variants associated with a common complex trait.

Neural manipulations were used to examine the mechanisms that underlie the acquired equivalence and distinctiveness of cues in rats. Control rats and those with excitotoxic lesions of either the hippocampus (HPC) or entorhinal cortex (EC) acquired the following conditional discrimination: In Contexts A and B, Stimulus X-->food and Stimulus Y-->no food, and in Contexts C and D, Y-->food and X-->no food. Rats then received many food pellets in A but not in C. After this treatment, control rats showed more magazine activity in B than in D--an acquired equivalence-distinctiveness effect. This effect was also evident in HPC rats but not in EC rats. These results indicate that changes in stimulus distinctiveness are dissociable from the process of conditional learning.

BACKGROUND Use of anti-arrhythmic drugs is limited by the high incidence of serious adverse events including QT prolongation and torsades de pointes. Recent studies have demonstrated a role for NOS1AP gene variants in modulating QT interval in healthy subjects and modification of the severity of presentation and the risk of arrhythmias in LQTS. METHODS We carried out an association study using 167 SNPs spanning the NOS1AP gene in 58 Caucasian patients experiencing dLQTS and 87 Caucasian controls from the DARE Study. RESULTS Association analysis identified one polymorphism significantly associated with dLQTS (rs10800397: p=3.7×10−4; OR=3.3, 99.95% CI=1.0–10.8). The associations were more pronounced in the subgroup of amiodarone users, in which three SNPs including rs10800397 were significantly associated (most significant SNP rs10919035: p=3.0×10−4; OR=5.5, 99.95% CI=1.1–27.9). We genotyped rs10919035 in an independent replication cohort of 28 amiodarone-dLQTS cases versus 173 controls (meta-analysis of both studies: OR=2.81; p=2.4×10−4; 95% CI=1.62–4.89). Analysis of QTc among 74 controls from our dataset showed a similar pattern of significance over the gene region as the case-control analysis. This pattern was confirmed in 1,480 controls from the BRIGHT cohort (top SNP DARE rs12734991 in meta-analysis: mean [SD] increase in QTc interval per C allele=9.1 [3.2]ms; p=1.7×10−4). CONCLUSIONS Our results provide the first demonstration that common variations in the NOS1AP gene are associated with a significant increase in the risk of dLQTS. We suggest that common variation in the NOS1AP gene may have relevance for future pharmacogenomic applications in clinical practice permitting safer prescription of drugs for vulnerable patients.