Sang Kun Lee

Cyclooxygenase-2 inhibitor, celecoxib, inhibits the altered hippocampal neurogenesis with attenuation of spontaneous recurrent seizures following pilocarpine-induced status epilepticus

Recent evidences suggest key roles of abnormal neurogenesis and astrogliosis in the pathogenesis of epilepsy. Alterations in the microenvironment of the stem cell, such as microglial activation and cyclooxygenase-2 induction may cause ectopic neurogenesis or astrogliosis. Here, we examined if inflammatory blockade with celecoxib, a selective cyclooxygenase-2 inhibitor, could modulate the altered microenvironment in the epileptic rat brain. Celecoxib attenuated the likelihood of developing spontaneous recurrent seizures after pilocarpine-induced prolonged seizure. During the latent period, celecoxib prevented neuronal death and microglia activation in the hilus and CA1 and inhibited the generation of ectopic granule cells in the hilus and new glia in CA1. The direct inhibition of precursor cells by celecoxib was further demonstrated in human neural stem cells culture. These findings raise the evidence of COX-2 induction to act importantly on epileptogenesis and suggest a potential therapeutic role for COX-2 inhibitors in chronic epilepsy.

Surgical Outcome and Prognostic Factors of Cryptogenic Neocortical Epilepsy

Surgical treatment of cryptogenic neocortical epilepsy is challenging. The aim of this study was to evaluate surgical outcomes and to identify possible prognostic factors including the results of various diagnostic tools. Eighty‐nine patients with neocortical epilepsy with normal magnetic resonance imaging (35 patients with frontal lobe epilepsy, 31 with neocortical temporal lobe epilepsy, 11 with occipital lobe epilepsy, 11 with parietal lobe epilepsy, and 1 with multifocal epilepsy) underwent invasive study and focal surgical resection. Patients were observed for at least 2 years after surgery. The localizing values of interictal electroencephalogram (EEG), ictal scalp EEG, interictal 18F‐fluorodeoxyglucose positron emission tomography (FDG‐PET), and subtraction ictal single‐photon emission computed tomography were evaluated. Seventy‐one patients (80.0%) had a good surgical outcome (Engel class 1–3); 42 patients were seizure free. Diagnostic sensitivities of interictal EEG, ictal scalp EEG, FDG‐PET, and subtraction ictal single‐photon emission computed tomography were 37.1%, 70.8%, 44.3%, and 41.1%, respectively. Localization by FDG‐PET and interictal EEG was correlated with a seizure‐free outcome. The localizing value of FDG‐PET was greatest in neocortical temporal lobe epilepsy. The focalization of ictal onset and also ictal onset frequency in invasive studies were not related to surgical outcome. Concordance with two or more presurgical evaluations was significantly related to a seizure‐free outcome. Ann Neurol 2005

Altered microRNA regulation in Huntington's disease models.

Huntingtons disease (HD) is a genetic neurodegenerative disease caused by abnormal CAG expansion. MicroRNAs (miRNAs) are short RNA molecules regulating gene expression, and are implicated in a variety of diseases including HD. However, the profiles and regulation of miRNAs in HD are not fully understood. Here, we analyzed the miRNA expression and miRNA regulators in two transgenic models of HD, YAC128 and R6/2 mice, and in a 3-nitropropionic acid (3NP)-induced striatal degeneration rat model. After characterizing the phenotypes by behavioral tests and histological analyses, we profiled striatal miRNAs using a miRNA microarray and we measured the key molecules involved in miRNA biogenesis and function. YAC128 mice showed upregulation-dominant miRNA expressions at 5 months and downregulation-dominant expressions at 12 months. Concomitantly, the expressions of Drosha-DGCR8, Exportin-5, and Dcp1 were increased at 5months, and the expression of Dicer was decreased at 12 months. In 10-week-old R6/2 mice, downregulation was dominant in the miRNA expressions and the level of Drosha decreased concomitantly. Nine miRNAs (miR-22, miR-29c, miR-128, miR-132, miR-138, miR-218, miR-222, miR-344, and miR-674*) were commonly down-regulated in both the 12-month-old YAC128 and 10-week-old R6/2 mice. Meanwhile, 3NP rats showed dynamic changes in the miRNA profiles during disease development and a few miRNAs with altered expression. Our results show that transgenic HD mice have abnormal miRNA biogenesis. This information should aid in future studies on therapeutic application of miRNAs in HD.

Systemic transplantation of human adipose stem cells attenuated cerebral inflammation and degeneration in a hemorrhagic stroke model

Adipose-derived stem cells (ASCs) are readily accessible multipotent mesenchymal stem cells and are known to secrete multiple growth factors, and thereby to have cytoprotective effects in various injury models. In the present study, the authors investigated the neuroprotective effect of ASCs in an intracerebral hemorrhage (ICH) model. ICH was induced via the stereotaxic infusion of collagenase, and human ASCs (three million cells per animal) isolated from human fresh fat tissue, were intravenously administered at 24 h post-ICH induction. Acute brain inflammation markers, namely, cell numbers positively stained for terminal transferase dUTP nick end labeling (TUNEL), myeloperoxidase (MPO), or OX-42, and brain water content were checked at 3 days post-ICH. In addition, the authors quantified brain degeneration by measuring hemispheric atrophy and perihematomal glial thickness at 6 weeks post-ICH, and determined modified limb placing behavioral scores weekly over 5 weeks post-ICH. The results showed that brain water content, TUNEL+, and MPO+ cell numbers were significantly reduced in the ASC-transplanted rats. ASC transplantation attenuated neurological deficits from 4 to 5 weeks post-ICH, and reduced both the brain atrophy and the glial proliferation at 6 weeks. Transplanted ASCs were found to densely populate perihematomal areas at 6 weeks, and to express endothelial markers (von Willebrand factor and endothelial barrier antigen), but not neuronal or glial markers. In summary, ASCs transplantation in the ICH model reduced both acute cerebral inflammation and chronic brain degeneration, and promoted long-term functional recovery.

Continuous cytosine-b-D-arabinofuranoside infusion reduces ectopic granule cells in adult rat hippocampus with attenuation of spontaneous recurrent seizures following pilocarpine-induced status epilepticus.

Brief or prolonged seizures induce various patterns of plasticity. Axonal or dendritic remodelling and development of ectopic granule cells have been described in the hilus and molecular layer of the adult rodent hippocampus. Hippocampal cell proliferation also occurs after seizures. However, whether the seizure‐induced cell proliferation plays a pathological or reparative role in the epileptic brain is unknown. In this study, we attempted to suppress the seizure‐induced cell proliferation with the antimitotic agent cytosine‐b‐D‐arabinofuranoside (Ara‐C) and to examine the development of spontaneous recurrent seizures (SRS). Experimental status epilepticus was induced with pilocarpine, and Ara‐C or vehicle alone was infused continuously with an osmotic minipump. SRS were video‐monitored. BrdU immunohistochemistry was used for the spatial and temporal analysis of hippocampal cell proliferation, and double labelling with NeuN, calbindin and GFAP antibodies was performed for the differentiation of BrdU‐positive cells. Timm staining was also performed for evaluation of mossy fibre sprouting (MFS). With continuous Ara‐C infusion, the likelihood of developing SRS was decreased and, during the latent period, the development of ectopic granule cells in the hilus and new glia in the CA1 area was reduced when compared with the vehicle‐infused group, while MFS was not altered. The results suggest that the hippocampal cell proliferation plays a pro‐epileptogenic role rather than a compensatory role, and that the epileptogenic process may be associated with the generation of new glia in the CA1 area and/or new neurons in the dentate gyrus, particularly the ectopically located hilar granule cells.

Pharmacological Induction of Ischemic Tolerance by Glutamate Transporter-1 (EAAT2) Upregulation

Background and Purpose— Astrocytic glutamate transporter protein, GLT-1 (EAAT2), recovers extracellular glutamate and ensures that neurons are protected from excess stimulation. Recently, &bgr;-lactam antibiotics, like ceftriaxone (CTX), were reported to induce the upregulation of GLT-1. Here, we investigated ischemic tolerance induction by CTX in an experimental model of focal cerebral ischemia. Methods— CTX (200 mg/kg per day, IP) was administered for 5 consecutive days before transient focal ischemia, which was induced by intraluminal thread occlusion of the middle cerebral artery for 90 minutes or permanently. Results— Repeated CTX injections enhanced GLT-1 mRNA and protein expressions after 3 and 5 days of treatment, respectively. CTX-pretreated animals showed a reduction in infarct volume by 58% (reperfusion) and 39% (permanent), compared with the vehicle-pretreated animals at 24 hours postischemia (P<0.01). Lower doses of CTX (20 mg/kg per day and 100 mg/kg per day) reduced infarct volumes to a lesser degree. The injection of GLT-1 inhibitor (dihydrokainate) at 30 minutes before ischemia ameliorated the effect of CTX pretreatment. However, CTX administration at 30 minutes after ischemia produced no significant reduction in infarct volume. CTX reduced the levels of proinflammatory cytokines (tumor necrosis factor-&agr;, FasL), matrix metalloproteinase (MMP)-9, and activated caspase-9 (P<0.01). In addition, CTX-pretreated animals showed better functional recovery at day 1 to week 5 after ischemia (P<0.05). Conclusions— This study presents evidence that CTX induces ischemic tolerance in focal cerebral ischemia and that this is mediated by GLT-1 upregulation.

miR-206 regulates brain-derived neurotrophic factor in Alzheimer disease model

Alzheimer disease (AD) brains are deficient in brain‐derived neurotrophic factor (BDNF), which regulates synaptic plasticity and memory. MicroRNAs (miRNAs) are ∼22‐nucleotide small noncoding RNAs that control a variety of physiological and disease processes. Here, we show that miR‐206 regulates BDNF and memory function in AD mice.

MicroRNAs Induced During Ischemic Preconditioning

Background and Purpose— MicroRNAs (miRNA) are single-stranded short RNA molecules that regulate gene expression by either degradation or translational repression of mRNA. Although miRNAs control a number of conditions and diseases, few neuroprotective miRNAs have been described. In this study, we investigated neuroprotective miRNAs induced early in ischemic preconditioning. Methods— Ischemic preconditioning or focal cerebral ischemia was induced in mice by transient occlusion of the middle cerebral artery for 15 or 120 minutes. We prepared RNA samples from the ischemic cortex at 3 or 24 hours after the onset of ischemia. Selective miRNAs then were synthesized and transfected into Neuro-2a cells before oxygen–glucose deprivation. Results— We detected a total of 360 miRNAs. Two miRNA families, miR-200 and miR-182, were selectively upregulated at 3 hours after ischemic preconditioning. Transfections of some of these were neuroprotective in in vitro ischemia. Among them, miR-200b, miR-200c, and miR-429 targeted prolyl hydroxylase 2 and had the best neuroprotective effect. Conclusion— Two miRNA families, miR-200 and miR-182, were upregulated early after ischemic preconditioning and the miR-200 family was neuroprotective mainly by downregulating prolyl hydroxylase 2 levels. These miRNAs may be useful in future research and therapeutic applications.

Prognostic factors in neocortical epilepsy surgery : Multivariate analysis

Summary:  Purpose: Defining prognostic factors for neocortical epilepsy surgery is important for the identification of ideal candidates and for predicting the prognosis of individual patients. We use multivariate analysis to identify favorable prognostic factors for neocortical epilepsy surgery.

HUMAN NEURAL STEM CELL TRANSPLANTATION REDUCES SPONTANEOUS RECURRENT SEIZURES FOLLOWING PILOCARPINE-INDUCED STATUS EPILEPTICUS IN ADULT RATS

Transplantation of neural stem cells (NSCs) can replace lost neurons and improve the functional deficits. Cell transplantation strategies have been tried in the epileptic disorder, but the effect of exogenous NSCs is unknown. In this study, we attempted to test the anti-epileptogenic effect of NSCs in adult rats with status epilepticus. Experimental status epilepticus was induced by lithium-pilocarpine injection, and beta galactosidase-encoded human NSCs were transplanted intravenously on the next day of status epilepticus. Spontaneous recurrent seizures were monitored with Racines seizure severity scale. Immunohistochemistry with anti-beta gal, Tuj-1, NeuN, GFAP, CNPase, GluR2, parvalbumin, and GABA were performed and extracellular field excitatory postsynaptic potentials (fEPSP) were recorded. Human NSCs suppressed spontaneous recurrent seizure formation and transplanted NSCs were differentiated into GABA-immunoreactive interneurons in the damaged hippocampus. Amplitude of fEPSP in the hippocampal CA1 was reduced, which was reversed by picrotoxin. These findings suggest that NSCs could be differentiated into inhibitory interneurons and decrease neuronal excitability, which could prevent spontaneous recurrent seizure formation in adult rats with pilocarpine-induced status epilepticus.