Normalization of mRNA levels using endogenous reference genes (ERGs) is critical for an accurate comparison of gene expression between different samples. Despite the popularity of traditional ERGs (tERGs) such as GAPDH and ACTB, their expression variability in different tissues or disease status has been reported. Here, we first selected candidate housekeeping genes (HKGs) using human gene expression data from different platforms including EST, SAGE, and microarray, and 13 novel ERGs (nERGs) (ARL8B, CTBP1, CUL1, DIMT1L, FBXW2, GPBP1, LUC7L2, OAZ1, PAPOLA, SPG21, TRIM27, UBQLN1, ZNF207) were further identified from these HKGs. The mean coefficient variation (CV) values of nERGs were significantly lower than those of tERGs and the expression level of most nERGs was relatively lower than high expressing tERGs in all dataset. The higher expression stability and lower expression levels of most nERGs were validated in 108 human samples including formalin-fixed paraffin-embedded (FFPE) tissues, frozen tissues and cell lines, through quantitative real-time RT-PCR (qRT-PCR). Furthermore, the optimal number of nERGs required for accurate normalization was as few as two, while four genes were required when using tERGs in FFPE tissues. Most nERGs identified in this study should be better reference genes than tERGs, based on their higher expression stability and fewer numbers needed for normalization when multiple ERGs are required.

Purpose We investigated the frequency and clinical significance of amyloid β (Aβ) positivity on PET in cerebral amyloid angiopathy (CAA) patients. MethodsWe recruited 65 patients who met the modified Boston criteria for probable CAA.All underwent amyloid PET, MRI, APOE genotyping and neuropsychological tests, and we obtained information of CAA and ischemic cerebral small vessel disease (CSVD) MRI markers. We investigated the CAA/ischemic CSVD burden and APOE genotypes by Aβ positivity and investigated the effect of Aβ positivity on longitudinal cognitive decline. Results Among 65 CAA patients, 43(66.2 %) showed Aβ PET positivity(+). Aβ+ CAA had more lobar microbleeds(9(2,41) vs. 3(2,8), p=0.045) and a higher frequency of cortical superficial siderosis(34.9 vs. 9.1%, p=0.025), while Aβ-CAA had more lacunes(1(0,2) vs. 0(0,1), p=0.029) and a higher frequency of severe white matter hyperintensities(45.5 vs. 20.9%, p=0.040). The frequency of ε4 carriers was higher in Aβ+(57.1%) than in Aβ-CAA(18.2%) (p=0.003) while the frequency of ε2 carriers did not differ between two groups.Finally, Aβ positivity was associated with faster decline in multiple cognitive domains including language (p<0.001), visuospatial function (p<0.001), and verbal memory (p<0.001) in linear mixed effects models.3 Conclusions Our findings suggest that a significant proportion of probable CAA patients in a memory clinic are Aβ PET negative. Aβ positivity in CAA patients is associated with a distinct pattern of CSVD biomarker expression, and a worse cognitive trajectory. Aβ positivity has clinical relevance in CAA and might represent either advanced CAA or additional Alzheimer's disease neuropathologic changes.

We demonstrated a downward spreading pattern of amyloid, suggesting that amyloid accumulates first in neocortex followed by subcortical structures. Furthermore, our new finding suggested that an amyloid staging scheme based on subcortical involvement might reveal how differential regional accumulation of amyloid affects cognitive decline through functional and structural changes of the brain.

Background and PurposeThere is accumulating evidence that epilepsy is caused by network dysfunction. We evaluated the hub reorganization of subcortical structures in patients with focal epilepsy using graph theoretical analysis based on diffusion-tensor imaging (DTI). In addition, we investigated differences in the values of diffusion tensors and scalars, fractional anisotropy (FA), and mean diffusivity (MD) of subcortical structures between patients with focal epilepsy and healthy subjects.MethodsOne hundred patients with focal epilepsy and normal magnetic resonance imaging (MRI) findings and 80 age- and sex-matched healthy subjects were recruited prospectively. All subjects underwent DTI to obtain data suitable for graph theoretical analysis. We investigated the differences in the node strength, cluster coefficient, eigenvector centrality, page-rank centrality measures, FA, and MD of subcortical structures between patients with epilepsy and healthy subjects.ResultsAfter performing multiple corrections, the cluster coefficient and the eigenvector centrality of the globus pallidus were higher in patients with epilepsy than in healthy subjects (p=0.006 and p=0.008, respectively). In addition, the strength and the page-rank centrality of the globus pallidus tended to be higher in patients with epilepsy than in healthy subjects (p=0.092 and p=0.032, respectively). The cluster coefficient of the putamen was lower in patients with epilepsy than in healthy subjects (p=0.004). The FA values of the caudate nucleus and thalamus were significantly lower in patients with epilepsy than in healthy subjects (p=0.009 and p=0.007, respectively), whereas the MD value of the thalamus was higher than that in healthy subjects (p=0.005).ConclusionsWe discovered the presence of hub reorganization of subcortical structures in focal epilepsy patients with normal MRI findings, suggesting that subcortical structures play a pivotal role as a hub in the epilepsy network. These findings further reinforce the idea that epilepsy is a network disease.

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