Epilepsy affects approximately 0,5-1% of children. Epileptic seizures originate in and propagate along certain neural pathways involved in physiological processes of cognition. Consequently, cognitive impairment frequently accompanies epilepsy in childhood and contributes to diminished quality of life of these patients.The main goal of this PhD thesis was to study multiple aspects of cognitive impairment in children suffering from intractable focal epilepsy. In the first and primary study, we described for the first time the negative impact of quasi- periodic epileptiform discharges in sleep (termed "hurdles" in our work) on cognitive functions in children with focal structural epilepsy. We have also shown that epileptiform activity in sleep has a more prominent negative impact on cognitive functions than epileptiform activity in wake. Although "hurdles" are by definition generalized, they do not predict worse outcomes of epilepsy surgery, compared to controls. In the second study, we analyzed the relationship between the extent of epileptogenic zone, functional brain plasticity (evaluated by fMRI) and cognitive dysfunction in children with drug resistant temporal epilepsy. Comparing patients with isolated focal cortical dysplasia (FCD) and patients with combined pathology (FCD and hippocampal...

Vascular endothelial growth factor (VEGF) is a potent angiogenic agent. VEGF activates its biologic responses through two cell-surface receptors, Flt1 and Flk1. In addition to the transmembrane form of Flt1, the Flt1 gene also encodes a secreted, truncated form of the receptor (sFlt1) translated from an mRNA in which a portion of intron 13 is preserved. sFlt1 retains high affinity for VEGF and thereby inhibits its angiogenic activity. Intron 13 contains important cis elements involved in sFlt1 mRNA formation. Here, we test the hypothesis that polymorphisms in the human Flt1 gene, particularly SNPs at sites suspected to contain splicing or cleavage-polyadenylation signals, influence Flt1 pre-mRNA processing and rates of Flt1 and sFlt1 expression. The NCBI SNP database contained 23 SNPs in the region of interest, one each in exons 13 and 14. An independent human SNP screen confirmed several of the reported SNPs. The web-based ESEfinder software predicted that the exon 13/14 SNPs had reduced potential for recruitment of splicing components. To test effects of exonic SNPs on Flt1 pre-mRNA processing, wild type and mutant Flt1 minigene plasmids were transfected into NIH/3T3 cells. Both exonic SNPs were associated with ~40% decreases in Flt1:sFlt1 mRNA ratios determined by real-time PCR. To facilitate exploration of ESEs in regulated RNA splicing, a PERL computer program, "EXONerator" was written to silence predicted ESEs without altering polypeptide sequence. These results support the notion that small changes in exon composition can have significant effects on splicing activity and underscore the utility of software tools for hypothesis generation. / Ph. D.