Reduced phosphorylation of brain insulin receptor substrate and Akt proteins in apolipoprotein-E4 targeted replacement mice

10.1038/srep03754Scientific Reports4

Reference Cluster Normalization Improves Detection of Frontotemporal Lobar Degeneration by Means of FDG-PET.

Positron emission tomography with [18F] fluorodeoxyglucose (FDG-PET) plays a well-established role in assisting early detection of frontotemporal lobar degeneration (FTLD). Here, we examined the impact of intensity normalization to different reference areas on accuracy of FDG-PET to discriminate between patients with mild FTLD and healthy elderly subjects. FDG-PET was conducted at two centers using different acquisition protocols: 41 FTLD patients and 42 controls were studied at center 1, 11 FTLD patients and 13 controls were studied at center 2. All PET images were intensity normalized to the cerebellum, primary sensorimotor cortex (SMC), cerebral global mean (CGM), and a reference cluster with most preserved FDG uptake in the aforementioned patients group of center 1. Metabolic deficits in the patient group at center 1 appeared 1.5, 3.6, and 4.6 times greater in spatial extent, when tracer uptake was normalized to the reference cluster rather than to the cerebellum, SMC, and CGM, respectively. Logistic regression analyses based on normalized values from FTLD-typical regions showed that at center 1, cerebellar, SMC, CGM, and cluster normalizations differentiated patients from controls with accuracies of 86%, 76%, 75% and 90%, respectively. A similar order of effects was found at center 2. Cluster normalization leads to a significant increase of statistical power in detecting early FTLD-associated metabolic deficits. The established FTLD-specific cluster can be used to improve detection of FTLD on a single case basis at independent centers - a decisive step towards early diagnosis and prediction of FTLD syndromes enabling specific therapies in the future

Development and implementation of a novel assay for L-2-hydroxyglutarate dehydrogenase (L-2-HGDH) in cell lysates: L-2-HGDH deficiency in 15 patients with L-2-hydroxyglutaric aciduria

l-2-hydroxyglutaric aciduria (l-2-HGA) is a rare inherited autosomal recessive neurometabolic disorder caused by mutations in the gene encoding l-2-hydroxyglutarate dehydrogenase. An assay to evaluate l-2-hydroxyglutarate dehydrogenase (l-2-HGDH) activity in fibroblast, lymphoblast and/or lymphocyte lysates has hitherto been unavailable. We developed an l-2-HGDH enzyme assay in cell lysates based on the conversion of stable-isotope-labelled l-2-hydroxyglutarate to 2-ketoglutarate, which is converted into l-glutamate in situ. The formation of stable isotope labelled l-glutamate is therefore a direct measure of l-2-HGDH activity, and this product is detected by liquid chromatography-tandem mass spectrometry. A deficiency of l-2-HGDH activity was detected in cell lysates from 15 out of 15 l-2-HGA patients. Therefore, this specific assay confirmed the diagnosis unambiguously affirming the relationship between molecular and biochemical observations. Residual activity was detected in cells derived from one l-2-HGA patient. The l-2-HGDH assay will be valuable for examining in vitro riboflavin/FAD therapy to rescue l-2-HGDH activity. © 2009 SSIEM and Springer