Seizure Outcomes and Predictors of Recurrent Post-Stroke Seizure: A Retrospective Observational Cohort Study

Background

Seizure is a common complication after stroke (termed “post-stroke seizure,” PSS). Although many studies have assessed outcomes and risk factors of PSS, no reliable predictors are currently available to determine PSS recurrence. We compared baseline clinical characteristics and post-stroke treatment regimens between recurrent and non-recurrent PSS patients to identify factors predictive of recurrence.

Methods

Consecutive PSS patients admitted to our stroke center between January 2011 and July 2013 were monitored until February 2014 (median 357 days; IQR, 160–552) and retrospectively evaluated for baseline clinical characteristics and PSS recurrence. Cumulative recurrence rates at 90, 180, and 360 days post-stroke were estimated by Kaplan—Meier analysis. Independent predictors of recurrent PSS were identified by Cox proportional-hazards analysis.

Results

A total of 104 patients (71 men; mean age, 72.1 ± 11.2 years) were analyzed. PSS recurred in 31 patients (30%) during the follow-up. Factors significantly associated with PSS recurrence by log-rank analysis included previous PSS, valproic acid (VPA) monotherapy, polytherapy with antiepileptic drugs (AEDs), frontal cortical lesion, and higher modified Rankin Scale score at discharge (all p < 0.05). Independent predictors of recurrent PSS were age <74 years (HR 2.38, 95% CI 1.02–5.90), VPA monotherapy (HR 3.86, 95% CI 1.30–12.62), and convulsions on admission (HR 3.87, 95% CI 1.35–12.76).

Conclusions

Approximately one-third of PSS patients experienced seizure recurrence within one year. The predictors of recurrent PSS were younger age, presence of convulsions and VPA monotherapy. Our findings should be interpreted cautiously in countries where monotherapy with second-generation AEDs has been approved because this study was conducted while second-generation AEDs had not been officially approved for monotherapy in Japan.     

Immunohistochemical Localization of Arginase II and Other Enzymes of Arginine Metabolism in Rat Kidney and Liver

Arginine is a precursor for the synthesis of urea, polyamines, creatine phosphate, nitric oxide and proteins. It is synthesized from ornithine by argininosuccinate synthetase and argininosuccinate lyase and is degraded by arginase, which consists of a liver-type (arginase I) and a non-hepatic type (arginase II). Recently, cDNAs for human and rat arginase II have been isolated. In this study, immunocytochemical analysis showed that human arginase II expressed in COS-7 cells was localized in the mitochondria. Arginase II mRNA was abundant in the rat small intestine and kidney. In the kidney, argininosuccinate synthetase and lyase were immunostained in the cortex, intensely in proximal tubules and much less intensely in distal tubules. In contrast, arginase II was stained intensely in the outer stripes of the outer medulla, presumably in the proximal straight tubules, and in a subpopulation of the proximal tubules in the cortex. Immunostaining of serial sections of the kidney showed that argininosuccinate synthetase and arginase II were collocalized in a subpopulation of proximal tubules in the cortex, whereas only the synthetase, but not arginase II, was present in another subpopulation of proximal tubules. In the liver, all the enzymes of the urea cycle, i.e. carbamylphosphate synthetase I, ornithine transcarbamylase, argininosuccinate synthetase and lyase and arginase I, showed similar zonation patterns with staining more intense in periportal hepatocytes than in pericentral hepatocytes, although zonation of ornithine transcarbamylase was much less prominent. The implications of these results are discussed.     

Effects of the core lipid on the energetics of binding of ApoA-I to model lipoprotein particles of different sizes

Interaction of apolipoproteins (apo) with lipid surfaces plays crucial roles in lipoprotein metabolism and cholesterol homeostasis. To elucidate the thermodynamics of binding of apoA-I to lipid, we used lipid emulsions composed of triolein (TO) and egg phosphatidylcholine (PC) as lipoprotein models. Determination of the level of binding of wild-type (WT) apoA-I and some deletion mutants to large (120 nm diameter; LEM) and small (35 nm diameter; SEM) emulsions indicated that N-terminal (residues 44-65) and C-terminal (residues 190-243 and 223-243) deletions have large effects on lipid interaction, whereas deletion of the central region (residues 123-166) has little effect. Substitution of amino acids at either L230 or L230, L233, and Y236 with proline residues also decreases the level of binding, indicating that an alpha-helix conformation in this C-terminal region is required for efficient lipid binding. Calorimetry showed that binding of WT apoA-I to SEM generates endothermic heat (DeltaH approximately 30 kcal/mol) in contrast to the exothermic heat (ca. -85 kcal/mol) generated upon binding to LEM and egg PC small unilamellar vesicles (SUV). This exothermic heat arises from an approximately 25% increase in alpha-helix content, and it drives the binding of apoA-I to LEM and SUV. There is a similar increase in alpha-helix content of apoA-I upon binding to either SEM or SUV, but the binding of apoA-I to SEM is an entropy-driven process. These results suggest that the presence of a core triglyceride modifies the highly curved SEM surface packing and thereby the thermodynamics of apoA-I binding in a manner that compensates for the exothermic heat generated by alpha-helix formation.     

Role of the basic C-terminal half of caldesmon in its regulation of F-actin: comparison between caldesmon and calponin

We previously reported that caldesmon (CaD), together with tropomyosin (TM), effectively protects actin filaments from gelsolin, an actin-severing protein. To elucidate the structure/function relationship of CaD, we dissected the functional domain of CaD required for the protection. The basic C-terminal half of rat nonmuscle CaD (D3) inhibits gelsolin activity to the same degree as intact CaD, although a smaller C-terminal region of D3 does not. This smaller C-terminal region contains the minimum regulatory domain responsible for the inhibition of actomyosin ATPase, and for the binding to actin, calmodulin and TM. These results suggest that the domain responsible for the inhibition of gelsolin activity lies outside the minimum regulatory domain, and that the positive charge possessed by the C-terminal half of CaD is important for its interaction with actin. Moreover, while the D3 fragment promotes the aggregation of F-actin into bundles as reported previously, this bundle formation is inhibited by the acidic N-terminal half of CaD, as well as by poly-l-glutamate. It seems likely that the acidic N-terminal half of CaD neutralizes the superfluous basic feature of the C-terminal half. A comparison between D3 and calponin, another actin-binding protein that is also basic and has similar actin-regulatory activities, is also discussed.     

Purification and properties of a phospholipase A2/lipase preferring phosphatidic acid,bis(monoacylglycerol) phosphate,and monoacylglycerol from rat testis

Phospholipase A(2) (PLA(2)) was purified to homogeneity from the supernatant fraction of rat testis homogenate. The purified 63-kDa enzyme did not require Ca(2+) ions for activity and exhibited both phosphatidic acid-preferring PLA(2) and monoacylglycerol lipase activities with a modest specificity toward unsaturated acyl chains. Anionic detergents enhanced these activities. Serine-modifying irreversible inhibitors, (p-amidinophenyl) methanesulfonyl fluoride and methylarachidonyl fluorophosphonate, inhibited both activities to a similar extent, indicating a single active site is involved in PLA(2) and lipase activities. The sequence of NH(2)-terminal 12 amino acids of purified enzyme was identical to that of a carboxylesterase from rat liver. The optimal pH for PLA(2) activity (around 5.5) differed from that for lipase activity (around 8.0). At pH 5.5 the enzyme also hydrolyzed bis(monoacylglycerol) phosphate, or lysobisphosphatidic acid (LBPA), that has been hitherto known as a secretory PLA(2)-resistant phospholipid and a late endosome marker. LBPA-enriched fractions were prepared from liver lysosome fractions of chloroquine-treated rats, treated with excess of pancreatic PLA(2), and then used for assaying LBPA-hydrolyzing activity. LBPA and the reaction products were identified by microbore normal phase high performance liquid chromatography/electrospray ionization ion-trap mass spectrometry. These enzymatic properties suggest that the enzyme can metabolize phosphatidic and lysobisphosphatidic acids in cellular acidic compartments.     

Molecular analysis of HLA-B39 subtypes

Serological studies have suggested the presence of a new HLA-B39 subtype (B39.2) in the Japanese population. To identify the new HLA-B39 subtype and compare it with an other HLA-B39 subtype (B39.1), the genes encoding HLA-B39.1 (B ^* 39013) and B39.2 (B ^* 3902) have been cloned from Japanese. We have sequenced these genes and completed the sequence of HLA-B39.1 (B ^*39011 ) gene from a Caucasian that was partially sequenced. Comparison of the sequence data revealed that B ^* 3902 and B ^* 39013 differ by three nucleotide substitutions which result in a two amino acids change at residues 63 and 67, while one silent substitution at codon 312 is found between B ^* 39011 and B ^* 39013. These results suggest that B ^* 3902 has evolved from B ^* 39013 rather than B ^* 39011.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers M94051 (HLA-B^*39013), M94052 (HLA-B^*39011), and M94053 (HLA-B^*3902).     

Gas7b (Growth Arrest Specific Protein 7b) Regulates Neuronal Cell Morphology by Enhancing Microtubule and Actin Filament Assembly

Neurons undergo several morphological changes as a part of normal neuron maturation process. Alzheimer disease is associated with increased neuroproliferation and impaired neuronal maturation. In this study, we demonstrated that Gas7b (growth arrest specific protein 7b) expression in a neuronal cell line, Neuro 2A, induces cell maturation by facilitating formation of dendrite-like processes and/or filopodia projections and that Gas7b co-localizes with neurite microtubules. Molecular analysis was performed to evaluate whether Gas7b associates with actin filaments and microtubules, and the data revealed two novel roles of Gas7b in neurite outgrowth: we showed that Gas7b enhances bundling of several microtubule filaments and connects microtubules with actin filaments. These results suggest that Gas7b governs neural cell morphogenesis by enhancing the coordination between actin filaments and microtubules. We conclude that lower neuronal Gas7b levels may impact Alzheimer disease progression.     

In Vivo Epigenomic Profiling of Germ Cells Reveals Germ Cell Molecular Signatures

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Highlights? Modified small-scale ChIP-seq method applicable to small number of cells ? Genome-wide maps of H3K4me3, H3K27me3, H3K27ac, and H2BK20ac of germ cells in vivo ? Identification of active and inactive regulatory elements in germ cells in vivo ? Germ cell H3K27me3 regions are enriched for retrotransposon repeats     

Role of internalization in the pathogenicity of Shiga toxin-producing Escherichia coli infection in a gnotobiotic murine model

We investigated the role of bacterial internalization in the killing caused by Shiga toxin-producing Escherichia coli (STEC) infection using a gnotobiotic murine model. A high number of internalized STEC was found in the colonic epithelial cells of STEC-infected mice by both an ex vivo assay and transmission electron microscopy. Most of these mice were killed within 10 days after infection. However, the implantation of lactic acid bacteria in such mice before infection markedly decreased the number of internalized STECs and also completely protected these hosts from killing by a STEC infection. The inhibition of such internalization by immunoglobulin also prevented the hosts from being killed. The Shiga toxin levels in these hosts indicated an inhibition of the penetration of Shiga toxins produced in the colon to the underlying tissue. These results suggested that the internalization plays an important role in the pathogenicity caused by STEC infection in a gnotobiotic murine model.