Poststroke seizure: optimising its management.

Seizure after stroke or poststroke seizure (PSS) is a common and very important complication of stroke. It can be divided into early seizure and late seizure, depending on seizure onset time after the stroke. It has been reported that ischaemic and haemorrhagic stroke accounts for about 11% of all adult epilepsy cases and 45% of epilepsy cases over 60 years of age. However, there are no reliable guidelines in clinical practice regarding most of the fundamental issues of PSS management. In recent years there has been an increased interest in the study of PSS which may give clinical practitioners a better picture of how to optimise PSS management. Studies have indicated two peaks in PSS occurrence-the first day and 6-12 months after a stroke. Haemorrhagic stroke, cortical involvement, severity of initial neurological deficit, younger patients (<65 years of age), family history of seizures and certain genetic factors carry a higher risk of PSS. The use of continuous electroencephalogram has demonstrated significant benefits in capturing interictal or ictal abnormalities, especially in cases of non-convulsive seizures and non-convulsive status epilepticus. Current available data indicated that there was no significant difference in antiepileptic efficacy among most of the antiepileptic drugs (AEDs) in PSS. Levetiracetam and lamotrigine are the most studied newer generation AEDs and have the best drug tolerance. The purpose of this review is to summarise the recent advances in PSS research and focus on the most important practice issues of PSS management.

Type II Restriction of Bacteriophage DNA With 5hmdU-Derived Base Modifications.

To counteract bacterial defense systems, bacteriophages (phages) make extensive base modifications (substitutions) to block endonuclease restriction. Here we evaluated Type II restriction of three thymidine (T or 5-methyldeoxyuridine, 5mdU) modified phage genomes: Pseudomonas phage M6 with 5-(2-aminoethyl)deoxyuridine (5-NedU), Salmonella phage ViI (Vi1) with 5-(2-aminoethoxy)methyldeoxyuridine (5-NeOmdU) and Delftia phage phi W-14 (a.k.a. ΦW-14) with α-putrescinylthymidine (putT). Among >200 commercially available restriction endonucleases (REases) tested, phage M6, ViI, and phi W-14 genomic DNAs (gDNA) show resistance against 48.4, 71.0, and 68.8% of Type II restrictions, respectively. Inspection of the resistant sites indicates the presence of conserved dinucleotide TG or TC (TS, S=C, or G), implicating the specificity of TS sequence as the target that is converted to modified base in the genomes. We also tested a number of DNA methyltransferases (MTases) on these phage DNAs and found some MTases can fully or partially modify the DNA to confer more resistance to cleavage by REases. Phage M6 restriction fragments can be efficiently ligated by T4 DNA ligase. Phi W-14 restriction fragments show apparent reduced rate in E. coli exonuclease III degradation. This work extends previous studies that hypermodified T derived from 5hmdU provides additional resistance to host-encoded restrictions, in parallel to modified cytosines, guanine, and adenine in phage genomes. The results reported here provide a general guidance to use REases to map and clone phage DNA with hypermodified thymidine.

Restriction and modification of deoxyarchaeosine (dG+)-containing phage 9 g DNA.

E. coli phage 9 g contains the modified base deoxyarchaeosine (dG+) in its genome. The phage encodes its own primase, DNA ligase, DNA polymerase, and enzymes necessary to synthesize and incorporate dG+. Here we report phage 9 g DNA sensitivity to >200 Type II restriction endonucleases (REases). Among the REases tested approximately 29% generated complete or partial digestions, while the remaining 71% displayed resistance to restriction. Phage 9 g restriction fragments can be degraded by DNA exonucleases or ligated by T3 and T4 DNA ligases. In addition, we examined a number of cytosine and adenine methyltransferases to generate double base modifications. M.AluI, M.CviPI, M.HhaI, and M.EcoGII were able to introduce 5mC or N6mA into 9 g DNA as confirmed by partial resistance to restriction and by liquid chromatography-mass spectrometry. A number of wild-type E. coli bacteria restricted phage 9 g, indicating natural restriction barriers exist in some strains. A BlastP search of GenBank sequences revealed five glutamine amidotransferase-QueC homologs in Enterobacteria and Pseudomonas phage, and distant homologs in other phage and bacterial genomes, suggesting that dG+ is not a rare modification. We also mapped phage 9 g DNA packaging (pac) site containing two 21-bp direct repeats and a major terminase cleavage site in the phage genome.

Proton MR Spectroscopy in Patients with Structural MRI-Negative Temporal Lobe Epilepsy.

BACKGROUND AND PURPOSE: With conventional magnetic resonance imaging (MRI), 20-30% of patients with temporal lobe epilepsy (TLE) have negative pathological MRI findings. Further investigations of the role of magnetic resonance spectroscopy (MRS) in the pre-surgical evaluation of patients with MRI-negative TLE are important to avoid intracranial EEG recording and to better understand the mechanism of the epileptogenic process. This study aimed to compare the measurements of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) in the hippocampi of MRI-negative TLE patients and normal subjects. METHODS: Twenty patients with MRI-negative TLE and 10 age-matched healthy control subjects underwent MRI and MRS. The concentrations of NAA, Cr, and Cho and the ratios of NAA/Cr and NAA/(Cr+Cho) were measured. Seven of these 20 patients also underwent surgical treatment for TLE. Their pathological results and surgical outcomes were evaluated. RESULTS: In the hippocampi ipsilateral to the seizure side, the NAA/Cr and NAA/(Cr+Cho) ratios were significantly decreased compared with the ratios of the hippocampi contralateral to the seizure side and the normal control hippocampi. There was no significant difference between the hippocampi contralateral to the seizure side and the normal control hippocampi. The pathological results from the patients who underwent temporal lobe resection indicated mild to moderate gliosis and minimal loss of neurons. Five patients were seizure-free during the follow-up period of 9- 47 months (mean 27.7 months). CONCLUSIONS: In MRI-negative TLE, significant reductions in the NAA/Cr and NAA/(Cr+Cho) ratios ipsilateral to the seizure side may help lateralize and localize the epileptogenic zone.