SNP Variation in MicroRNA Biogenesis Pathway Genes as a New Innovation Strategy for Alzheimer Disease Diagnostics: A Study of 10 Candidate Genes in an Understudied Population From the Eastern Mediterranean.

Alzheimer disease (AD) is a common complex neurodegenerative disorder accounting for nearly 50% to 70% of dementias worldwide. Yet the current diagnostic options for AD are limited. New diagnostic innovation strategies focusing on novel molecules and pathways are sorely needed. In this connection, microRNAs (miRNAs) are conserved small noncoding RNAs that regulate posttranscriptional gene expression and are vital for neuronal development and its functional sustainability. Conceivably, biological pathways responsible for the biogenesis of miRNAs represent a veritable set of upstream candidate genes that can be potentially associated with the AD pathophysiology. Notably, whereas functional single-nucleotide polymorphisms (SNPs) in miRNA biogenesis pathway genes have been studied in other complex diseases, surprisingly, virtually no such study has been conducted on their relevance in AD. Moreover, novel diagnostics identified in easily accessible peripheral tissues such as the whole blood samples represent the initial entry or gateway points on the biomarker discovery critical path for AD. To the best of our knowledge, we report here the first association study of functional SNPs, as measured by real-time PCR in 10 "upstream" candidate genes critically situated on the miRNA biogenesis pathway, in a large sample of AD patients (N=172) and healthy controls (N=109) in a hitherto understudied world population from the Mersin region of the Eastern Mediterranean. We observed a significant association between 2 candidate genes and AD, TARBP2 rs784567 genotype and AD (χ=6.292, P=0.043), and a trend for RNASEN rs10719 genotype (χ=4.528, P=0.104) and allele (P=0.035). Functional SNP variations in the other 8 candidate genes (DGCR8, XPO5, RAN, DICER1, AGO1, AGO2, GEMIN3, and GEMIN4) did not associate with AD in our sample. Given the putative biological importance of miRNA biogenesis pathways, these emerging data can provide a new foundation to stimulate future debate and genetic investigations of AD, focusing on new molecular mechanisms such as miRNA biogenesis, particularly in accessible peripheral tissues for novel molecular diagnostics for dementia.

Does the MRI or MRI contrast medium gadopentetate dimeglumine change the oxidant and antioxidant status in humans?

BACKGROUND: It has become evident that gadolinium-based contrast agents (GBCA) may have nephrotoxic potential. Oxidative stress is one of the most important pathways in the pathogenesis of iodinated contrast-induced nephropathy. PURPOSE: To investigate the effects of static magnetic fields and gadopentetate dimeglumine (Magnevist(®)) on oxidant/antioxidant status via measurement of total antioxidant capacity (TAC), total oxidant status (TOS), and serum malondialdehide (MDA). MATERIAL AND METHODS: Two age- and sex-matched groups of patients not under oxidative stress conditions that underwent magnetic resonance imaging (MRI) were recruited to this study. While contrast-enhanced (Magnevist(®), 0.2 mmol/kg) MRI was performed in group 1, MRI without GBCA was performed in group 2. Fasting blood glucose, C-reactive protein, serum creatinine, liver enzymes, uric acid, and lipid parameters were examined in all patients. Peripheral venous blood samples in order to determine TAC, TOS, and MDA were collected before and 6, 24, and 72 h after the MRI procedures. The TOS:TAC ratio was used as the oxidative stress index (OSI). Patients were followed up to 72 h. RESULTS: There were no significant changes in serum TAC, TOS, and MDA levels (Δ(serum TAC), Δ(serum TOS), and Δ(MDA)) in either group 6, 24, or 72 h after the procedures (P > 0.05). Furthermore, OSI did not change after the procedures in either group (P > 0.05). CONCLUSION: Magnetic field and gadopentetate dimeglumine (Magnevist(®)) do not change the oxidant or antioxidant status at a dose of 0.2 mmol/kg.