Summary Background Temporal lobe epilepsy is a common and frequently intractable seizure disorder. Its pathogenesis is thought to involve large-scale alterations to the expression of genes ...controlling neurotransmitter signalling, ion channels, synaptic structure, neuronal death, gliosis, and inflammation. Identification of mechanisms coordinating gene networks in patients with temporal lobe epilepsy will help to identify novel therapeutic targets and biomarkers. MicroRNAs (miRNAs) are a family of small non-coding RNAs that control the expression levels of multiple proteins by decreasing mRNA stability and translation, and could therefore be key regulatory mechanisms and therapeutic targets in epilepsy. Recent developments In the past 5 years, studies have found changes in miRNA levels in the hippocampus of patients with temporal lobe epilepsy and in neural tissues from animal models of epilepsy. Early functional studies showed that silencing of brain-specific miR-134 using antisense oligonucleotides (antagomirs) had potent antiseizure effects in animal models, whereas genetic deletion of miR-128 produced fatal epilepsy in mice. Levels of certain miRNAs were also found to be altered in the blood of rodents after seizures. In the past 18 months, functional studies have identified nine novel miRNAs that appear to influence seizures or hippocampal pathology. Their targets include transcription factors, neurotransmitter signalling components, and modulators of neuroinflammation. New approaches to manipulate miRNAs have been tested, including injection of mimics (agomirs) to enhance brain levels of miRNAs. Altered miRNA expression has also been reported in other types of refractory epilepsy and our understanding of how miRNA levels are controlled has grown, with studies on DNA methylation indicating epigenetic regulation. Biofluids (blood) of patients with epilepsy have shown differences in quantity of circulating miRNAs, implying diagnostic biomarker potential. Where next? Recent functional studies need to be replicated to build a robust evidence base. The specific cell types in which miRNAs execute their functions and their primary targets have to be identified, to fully explain the phenotypic effects of modulating miRNAs. Delivery of large molecules such as antisense inhibitors or mimics to the brain poses a challenge, and the multi-targeting effects of miRNAs create additional risks of unanticipated side effects. Potential genetic variation in miRNAs should be explored as the basis for disease susceptibility. The latest findings provide a rich source of new miRNA targets, but substantial challenges remain before their role in the pathogenesis, diagnosis, and treatment of epilepsy can be translated into clinical practice.
Background Cerebral microbleeds (CMB) are associated with an increased risk for ischemic and especially hemorrhagic stroke. The aim of the present study is to identify patients at high risk for the ...development of new CMB after initiation of an antiplatelet drug therapy. Methods Patients received magnetic resonance imaging (MRI) within 1 week after initiation of an antiplatelet drug treatment due to a first ischemic stroke (n = 58) and after a follow-up period of 6 months (n = 40). We documented the presence and the number of CMB at baseline and follow-up and analyzed the influence of possible risk factors including vascular risk factors, stroke etiology, and number of CMB at baseline using stepwise logistic regression and Spearman's correlation coefficient. We compared progression rates of CMB in relation to each risk factor using the Mann–Whitney U -test. Results The logistic regression model could correctly predict the presence of CMB in 70.7% of patients at baseline and 80% at follow-up. The model correctly identified 85% of patients with new CMB. We observed progression of CMB in 40% of the patients. The overall progression rate was .8 CMB per patient. The progression rate was significantly influenced by age more than 70 years and atherothrombotic stroke. The number of new CMB correlated significantly with the number of CMB at baseline. Conclusions We found several predictors of CMB after initiation of antiplatelet drug therapy. The results help to identify patients who need closer monitoring and thorough control of risk factors in order to lower the risk of new CMB and associated complications.
PDF
