Genetics of epilepsy: epilepsy research foundation workshop report.

The Sixth Epilepsy Research Foundation workshop, held in Oxford in March 2006, brought together basic scientists, geneticists, epidemiologists, statisticians, pharmacologists and clinicians to consider progress, issues and strategies for harnessing genetics to improve the understanding and treatment of the epilepsies. General principles were considered, including the fundamental importance of clear study design, adequate patient numbers, defi ned phenotypes, robust statistical data handling, and follow-up of genetic discoveries. Topics where some progress had been made were considered including chromosomal abnormalities, neurodevelopment, hippocampal sclerosis, juvenile myoclonic epilepsy, focal cortical dysplasia and pharmacogenetics. The ethical aspects of epilepsy genetics were reviewed. Principles and limitations of collaboration were discussed. Presentations and their matched discussions are produced here. There was optimism that further genetic research in epilepsy was not only feasible, but might lead to improvements in the lives of people with epilepsy.     

Epilepsy After Stroke

A retrospective follow-up of 200 consecutive stroke patients [ischemic brain infarction (IBI) 157, intracerebral hemorrhage (ICH) 20, subarachnoid hemorrhage (SAH) 23] who were in need of ambulatory rehabilitation was conducted for a mean period of 40 months after stroke. Epilepsy developed in 33 (17%) patients. The occurrence of epilepsy was 14% in IBI, 15% in ICH, and 35% in SAH. Significantly more patients developed epilepsy in the SAH group than in the IBI group (8 of 23 vs. 22 of 157, p less than 0.05). Of the 33 patients, 15% had their first seizures within the first 2 weeks after stroke, and 55% developed epilepsy in 6 months. Forty-eight percent of the patients had generalized seizures. Antiepileptic drug (AED) treatment was started in 28 of 33 patients, of whom 17 still had seizures during follow-up. Epilepsy was an important consequence of stroke among patients who needed rehabilitation, especially in SAH patients. In most, this was due to arterial spasm leading to IBI.     

Microangiographic changes of the pancreatic ducts in experimental chronic pancreatitis

Chronic pancreatitis was induced in eight piglets by dividing all pancreatic attachments to the duodenum. Five piglets served as controls. The animals which were operated on were autopsied six weeks thereafter. Ductography and microangiography were performed. Histological preparations of pancreatic tissue were made. All of the animals which underwent operation developed histologically verified chronic pancreatitis. Ductography revealed the main ducts and the side branches to be considerably dilated. They also exhibited variations in calibre and sudden obstructions. Two animals had a large non-infected pseudocyst. No communication between the cyst and the main duct could be demonstrated by ductography. No pancreatic calcifications were seen. The vasculature of the ductal plexuses seems to be derived from interlobular arteries. The animals with chronic pancreatitis had marked diminution of the vascular supply of the ducts. The changes in ductal vascularity correlated with the severity of the histological changes to the pancreas and may, thus, in part explain the progress of pancreatitis.     

Evaluation of dose-response models and parameters predicting radiation induced pneumonitis using clinical data from breast cancer radiotherapy

The purpose of this work is to evaluate the predictive strength of the relative seriality, parallel and LKB normal tissue complication probability (NTCP) models regarding the incidence of radiation pneumonitis, in a large group of patients following breast cancer radiotherapy, and furthermore, to illustrate statistical methods for examining whether certain published radiobiological parameters are compatible with a clinical treatment methodology and patient group characteristics. The study is based on 150 consecutive patients who received radiation therapy for breast cancer. For each patient, the 3D dose distribution delivered to lung and the clinical treatment outcome were available. Clinical symptoms and radiological findings, along with a patient questionnaire, were used to assess the manifestation of radiation-induced complications. Using this material, different methods of estimating the likelihood of radiation effects were evaluated. This was attempted by analysing patient data based on their full dose distributions and associating the calculated complication rates with the clinical follow-up records. Additionally, the need for an update of the criteria that are being used in the current clinical practice was also examined. The patient material was selected without any conscious bias regarding the radiotherapy treatment technique used. The treatment data of each patient were applied to the relative seriality, LKB and parallel NTCP models, using published parameter sets. Of the 150 patients, 15 experienced radiation-induced pneumonitis (grade 2) according to the radiation pneumonitis scoring criteria used. Of the NTCP models examined, the relative seriality model was able to predict the incidence of radiation pneumonitis with acceptable accuracy, although radiation pneumonitis was developed by only a few patients. In the case of modern breast radiotherapy, radiobiological modelling appears to be very sensitive to model and parameter selection giving clinically acceptable results in certain cases selectively (relative seriality model with Seppenwoolde et al and Gagliardi et al parameter sets). The use of published parameters should be considered as safe only after their examination using local clinical data. The variation of inter-patient radiosensitivity seems to play a significant role in the prediction of such low incidence rate complications. Scoring grades were combined to give stronger evidence of radiation pneumonitis since their differences could not be strictly associated with dose. This obviously reveals a weakness of the scoring related to this endpoint, and implies that the probability of radiation pneumonitis induction may be too low to be statistically analysed with high accuracy, at least with the latest advances of dose delivery in breast radiotherapy.     

Electrophysiologic changes in the lateral and basal amygdaloid nuclei in temporal lobe epilepsy: an in vitro study in epileptic rats

The functional consequences of neuronal loss during epileptogenesis in the lateral and basal amygdaloid nuclei are poorly understood. The present study tested the hypothesis that electrical responsiveness varies in different amygdaloid nuclei in the chronically epileptic amygdala. Further, we examined the amygdaloid region most prone to seizure initiation. Epileptogenesis was triggered in 20 rats by inducing status epilepticus (SE) with electrical stimulation of the lateral nucleus of the amygdala. Electrode-implanted non-stimulated rats served as controls. The occurrence and duration of spontaneous seizures were monitored with video-electroencephalography (EEG) at 8-9 weeks after SE. Thereafter, animals were killed and extracellular recordings were made from slices of both amygdalas. In the lateral nucleus of epileptic animals, the frequency of spontaneous responses was reduced compared with controls (P < 0.05). The amplitudes of evoked field responses were reduced (P < 0.01), whereas paired pulse (PP) facilitation was enhanced (P < or = 0.05). In the basal nucleus of the epileptic animals, PP facilitation was enhanced (P < 0.05) and sensitivity to 4-aminopyridine (4-AP)-induced epileptiform activity was increased compared with controls (P < 0.05). In the epileptic animals, the basal nucleus was also more sensitive than the lateral nucleus to 4-AP-induced epileptiform activity (P < 0.05). Correlation analysis indicated that longer SE duration was associated with longer half widths (P = 0.001) and smaller slopes (P < 0.05) of evoked responses as well as with attenuated PP facilitation (P<0.01). Moreover, a higher frequency of spontaneous seizures was associated with longer half widths (P < 0.05) and smaller slopes (P < 0.05) of evoked responses as well as with enhanced PP facilitation (P < 0.05). These data suggest that there is a reduced release of glutamate and reduced inhibition in the lateral and basal amygdaloid nuclei in epileptic animals. Further, the basal nucleus is more prone to epileptic activity than the lateral nucleus. Finally, the severity of SE and spontaneous seizures in vivo is associated with electrophysiologic alterations in vitro.     

Detection of human herpesvirus 6 and varicella-zoster virus in tear fluid of patients with Bell's palsy by PCR

Human herpesvirus 6 DNA was detected by PCR in the tear fluid of 7 (35%) of 20 patients with Bell's palsy and of 1 (5%) of 20 healthy controls. Varicella-zoster virus was detected by PCR in the tear fluid of 2 of 20 Bell's palsy patients but in none of the tear fluids from 20 healthy controls. These findings suggest an association between human herpesviruses and Bell's palsy.     

Serum prealbumin and retinol-binding protein in the prealbumin-related senile and familial forms of systemic amyloidosis

In a series of 13 elderly patients with proven prealbumin-related senile systemic amyloidosis (SSA), depressed serum prealbumin values (110.7 +/- 14.1 micrograms/ml) were found as compared to an age-matched control group (175.1 +/- 20.3 micrograms/ml). As expected, there was a significant correlation between serum prealbumin and serum retinol-binding proteins in both groups of patients. Patients with reactive amyloid protein AA amyloidosis had slightly depressed serum prealbumin concentrations, whereas patients with prealbumin-related familial amyloidosis of Swedish type had prealbumin values within normal limits. Since the serum levels of the acute phase reactants, haptoglobin and amyloid-related serum protein AA, were higher in the group of patients with reactive amyloidosis than in patients with SSA, the depression of the prealbumin levels in SSA is not a result of inflammation. Since SSA is known to contain prealbumin, it is possible that a disturbed prealbumin metabolism in old age results in low prealbumin serum values and deposition of amyloid.     

Caspase 6 expression in the rat hippocampus during epileptogenesis and epilepsy

The molecular basis of neuronal circuit reorganization during epileptogenesis is poorly understood. Such data are, however, critical for the search of new targets for the prevention of epileptogenesis. Here, we extended our previous studies on caspases in epileptogenesis by investigating the expression and activity of caspase 6 at different phases of the epileptic process in rats. Epileptogenesis was triggered by kainate-induced status epilepticus (SE) under video-electroencephalography-monitoring. Caspase 6 activity was measured fluorometrically in the hippocampus 8 h, 24 h, 48 h, 1 week, and 4 weeks after SE. Caspase 6 expression was examined using Western blot and immunohistochemistry. Our data demonstrated that the SE-induced increase in the expression of cleaved caspase 6 and its intraneuronal localization were dependent on the time delay from SE induction. Double-labeling with a neuronal marker, NeuN, indicated that within the first 48 h, caspase 6 immunoreactivity was present both in the hippocampal pyramidal cells and hilar neurons, some of which were also terminal transferase dUTP-end labeling-positive. This was coincident with a transient 18-fold increase in caspase 6 enzymatic activity. At the 1-week and 4-week time points, elevated caspase 6 immunoreactivity was detected in the dendritic processes and neuropil. These findings indicate that caspase 6 expression remains elevated long after the occurrence of acute cell death during epileptogenesis and epilepsy. Further, caspase 6 protein is not exclusively located in the somata of neurons, but also in dendrites. These data suggest that caspase 6 has functions other than execution of programmed cell death in epileptogenic hippocampus.     

The effects of d-cycloserine and MK-801 on the performance of rats in two spatial learning and memory tasks

The present study was undertaken to investigate the effects of modulation of the (NMDA) receptor on learning and memory. Thus, the performance of rats treated with d-cycloserine, a partial agonist at the glycine recognition site of the NMDA receptor complex, and MK-801, a noncompetitive NMDA receptor antagonist, either alone or concurrently were assessed in radial arm maze and water maze tasks. Administration of MK-801 (0.1 mg/kg, i.p.) impaired acquisition in the water maze (increased escape latency and distance) and working memory in the radial arm maze (increased re-entries) in rats. Moreover, in the radial arm maze, MK-801 disrupted locomotion (increased latencies and decreased arm entries per minute) and impaired the acquisition of reference memory (increased number of errors) performance of rats. d-Cycloserine (0.03, 0.3, 1.0, 3.0, 10 mg/kg, i.p.) had no effects on acquisition or memory performance of control or MK-801-treated rats in either of these tasks. However, d-cycloserine (0.03, 0.3, 3.0 mg/kg) reversed the MK-801-induced disruption in locomotion. Furthermore, 3.0 mg/kg d-cycloserine increased behavioral activity and also decreased the time needed to complete the task in control animals. To conclude, our results suggest that the consequences of NMDA receptor modulation on learning and memory processes and sensorimotor functions may be functionally different or have distinct anatomical locations.