Browsing by Issue Date, starting with "2013-06-17"
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- APOE isoforms in focal epilepsies: an association study in a Portuguese populationPublication . Martins da Silva, A.; Leal, B.; Chaves, J.; Carvalho, C.; Bettencourt, A.; Branco, R.C.; Ferreira, J.; Costa, P.; Martins da Silva, B.Purpose: Apolipoprotein E (ApoE) is the main lipoprotein secreted in brain. It has a critical immuno-modulatory function, influences neurotransmission and is involved in repairing damaged neurons. ApoE e4 allele is an isoform of ApoE with altered protein function previously associated with refractoriness and early onset epilepsy. Our purpose was to investigate if apoE isoforms are risk factors for partial epilepsy and to correlate genotypes with anti-epileptic drug response. Methods: A cohort of 230 epileptic patients with partial epilepsies from the outpatient clinic at HSA-CHP [109F, 121M; mean age = 44 13 years, age of onset = 15 13 years; 168 patients with Drug Refractory Epilepsy (DRE)] was compared with a cohort of 301 healthy individuals (HI) in a case control study. ApoE isoforms were genotype by RFLP-PCR methodology. Results: ApoE e4 allele frequency was higher in epileptic group when compared with HI (10.6% vs. 7.6%, p = n.s., OR = 1.44, 95% CI: 0.945–2.20). Anti-epileptic Drug response was not influenced by apoE isoforms. Conclusion: Our results suggest that ApoE e4 may be a risk factor for partial epilepsy development. ApoE e4 is associated with CNS network instability, with lower protection against oxidative and inflammatory cascade. These could influence neuronal growth and recovery leading to a chronic vicious cycle of damage and neuronal loss contributing to seizures development. These observations should be confirmed in a larger cohort.
- Human herpes virus 6B and mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS): is there a link?Publication . Leal, B.; Castelo Branco, R.; Rangel, R.; Chaves, J.; Carvalho, C.; Bettencourt, A.; Honavar, M.; Melo Pires, M.; Santos, A.; Magalhães, T.; Lopes, J.; Ramalheira, J.; Martins da Silva, A.; Costa, P.P.; Martins da Silva, B.Purpose: Human Herpesvirus 6 (HHV-6) is a ubiquitous virus acquired mainly during the first 2 years of life. Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis (MTLE-HS) is the most frequent pharmacoresistant epilepsy. One of the most common antecedents of MTLE-HS is febrile seizures (FS). Although the aetiology of MTLE-HS remains unclear, evidences suggest that HHV-6 infection could be implicated. The objective of this study was to investigate the presence of HHV-6B DNA in the hippocampus and adjoining temporal cortex of MTLE-HS patients submitted to surgery. Methods: A total of 22 MTLE-HS (13 females and nine males) cases were studied. The mean age at surgery was 39 9 years and mean age at onset of seizures was 10 6 years. These study cohort was compared to a group of 10 epileptic patients without MTLE-HS (six females, four males; mean age = 26 15 years) and with autopsy material from nine individuals without neurological disease. HHV-6B DNA was identified by real-time PCR with specific TaqMan probes. Results: We detected HHV-6B DNA in only one hippocampus from a MTLE-HS patient. This patient had a disease duration of 36 years and a history of febrile seizures in childhood. None of the non-MTLE or controls specimens showed positivity for HHV-6B. Conclusions: Our findings do not support a relevant etiologic role for HHV-6B in MTLE-HS, at least in this population. However, the possible role of viral infection in MTLE-HS epileptogenic process, in individual cases, cannot be excluded.
- Mesial temporal lobe epilepsy and serotonin: the role of HTR2A receptorPublication . Chaves, J.; Leal, B.; Carvalho, C.; Bettencourt, A.; Bras, S.; Barreira, A.; Boleixa, D.; Martins da Silva, A.; Costa, P.P.; Martins da Silva, B.Purpose: Evidences from animal models have demonstrated that depletion of brain serotonin (5-HT), a neurotransmitter with a pivotal role in neurodevelopment and brain plasticity, lowers the threshold to induced seizures. It was also demonstrated that anti-epileptic drugs increase endogenous 5-HT concentrations. Studies in brain tissue from Mesial Temporal lobe Epilepsy (MTLE) patients have showed that serotonin type 2a receptor (HTR2A) is downregulated in these patients. HTR2A expression levels may be modulated by a 102 T>C polymorphism. The aim of this study was to analyse the association between 102T>C polymorphism and the development and clinical features of MTLE-HS in a Portuguese population. Methods: A cohort of 112 MTLE-HS patients (62F, 50M, mean age = 44 11 years, age of onset = 13 9 years, 97 patients with drug refractory epilepsy) was compared with a cohort of 183 healthy individuals (HI). Genotyping was performed by Real Time PCR using High Melting Resolution methodology. Results: HTR2A 102 T>C genotype frequencies were similar between patients and controls (TT: 24.1% vs. 25.1% in HI; TC: 45.5% vs. 43.2% in HI; CC: 31.3% vs. 31.7% in HI). No association was found between this polymorphism and MTLE-HS clinical features (age of onset, FS antecedents and anti-epileptic drug response). Conclusion: The present results do not provide evidence that HTR2A polymorphism 102T>C may confer susceptibility to MTLE-HS. Nevertheless a possible role for the serotonergic system in epileptogenesis cannot be excluded. The study of other 5-HT receptors and transporters is underway.