Stresses that Raise Np4A Levels Induce Protective Nucleoside Tetraphosphate Capping of Bacterial RNA.

Present in all realms of life, dinucleoside tetraphosphates (Np4Ns) are generally considered signaling molecules. However, only a single pathway for Np4N signaling has been delineated in eukaryotes, and no receptor that mediates the influence of Np4Ns has ever been identified in bacteria. Here we show that, under disulfide stress conditions that elevate cellular Np4N concentrations, diverse Escherichia coli mRNAs and sRNAs acquire a cognate Np4 cap. Purified E. coli RNA polymerase and lysyl-tRNA synthetase are both capable of adding such 5' caps. Cap removal by either of two pyrophosphatases, ApaH or RppH, triggers rapid RNA degradation in E. coli. ApaH, the predominant decapping enzyme, functions as both a sensor and an effector of disulfide stress, which inactivates it. These findings suggest that the physiological changes attributed to elevated Np4N concentrations in bacteria may result from widespread Np4 capping, leading to altered RNA stability and consequent changes in gene expression.

A Novel RNA Phosphorylation State Enables 5' End-Dependent Degradation in Escherichia coli.

RNA modifications that once escaped detection are now thought to be pivotal for governing RNA lifetimes in both prokaryotes and eukaryotes. For example, converting the 5'-terminal triphosphate of bacterial transcripts to a monophosphate triggers 5' end-dependent degradation by RNase E. However, the existence of diphosphorylated RNA in bacteria has never been reported, and no biological role for such a modification has ever been proposed. By using a novel assay, we show here for representative Escherichia coli mRNAs that ~35%-50% of each transcript is diphosphorylated. The remainder is primarily monophosphorylated, with surprisingly little triphosphorylated RNA evident. Furthermore, diphosphorylated RNA is the preferred substrate of the RNA pyrophosphohydrolase RppH, whose biological function was previously assumed to be pyrophosphate removal from triphosphorylated transcripts. We conclude that triphosphate-to-monophosphate conversion to induce 5' end-dependent RNA degradation is a two-step process in E. coli involving γ-phosphate removal by an unidentified enzyme to enable subsequent ß-phosphate removal by RppH.

A distinct RNA recognition mechanism governs Np4 decapping by RppH.

Dinucleoside tetraphosphates, often described as alarmones because their cellular concentration increases in response to stress, have recently been shown to function in bacteria as precursors to nucleoside tetraphosphate (Np4) RNA caps. Removal of this cap is critical for initiating 5' end-dependent degradation of those RNAs, potentially affecting bacterial adaptability to stress; however, the predominant Np4 decapping enzyme in proteobacteria, ApaH, is inactivated by the very conditions of disulfide stress that enable Np4-capped RNAs to accumulate to high levels. Here, we show that, in Escherichia coli cells experiencing such stress, the RNA pyrophosphohydrolase RppH assumes a leading role in decapping those transcripts, preferring them as substrates over their triphosphorylated and diphosphorylated counterparts. Unexpectedly, this enzyme recognizes Np4-capped 5' ends by a mechanism distinct from the one it uses to recognize other 5' termini, resulting in a one-nucleotide shift in substrate specificity. The unique manner in which capped substrates of this kind bind to the active site of RppH positions the δ-phosphate, rather than the ß-phosphate, for hydrolytic attack, generating triphosphorylated RNA as the primary product of decapping. Consequently, a second RppH-catalyzed deprotection step is required to produce the monophosphorylated 5' terminus needed to stimulate rapid RNA decay. The unconventional manner in which RppH recognizes Np4-capped 5' ends and its differential impact on the rates at which such termini are deprotected as a prelude to RNA degradation could have major consequences for reprogramming gene expression during disulfide stress.

Np4A alarmones function in bacteria as precursors to RNA caps.

Stresses that increase the cellular concentration of dinucleoside tetraphosphates (Np4Ns) have recently been shown to impact RNA degradation by inducing nucleoside tetraphosphate (Np4) capping of bacterial transcripts. However, neither the mechanism by which such caps are acquired nor the function of Np4Ns in bacteria is known. Here we report that promoter sequence changes upstream of the site of transcription initiation similarly affect both the efficiency with which Escherichia coli RNA polymerase incorporates dinucleoside polyphosphates at the 5' end of nascent transcripts in vitro and the percentage of transcripts that are Np4-capped in E. coli, clear evidence for Np4 cap acquisition by Np4N incorporation during transcription initiation in bacterial cells. E. coli RNA polymerase initiates transcription more efficiently with Np4As than with ATP, particularly when the coding strand nucleotide that immediately precedes the initiation site is a purine. Together, these findings indicate that Np4Ns function in bacteria as precursors to Np4 caps and that RNA polymerase has evolved a predilection for synthesizing capped RNA whenever such precursors are abundant.

Success rate in micropulse diode laser treatment with regard to lens status, refractive errors, and glaucoma subtypes.

PURPOSE: To evaluate the efficacy of micropulse transscleral cyclophotocoagulation (MP-TSCPC) considering different characteristics: glaucoma subtypes and lens status. METHODS: A retrospective case-series study was designed to evaluate intraocular pressure (IOP), and the number of IOP-lowering medications, used by glaucoma patients treated with MP-TSCPC between 2016 and 2019. Cases had a follow-up period of 12 months. Achieving an IOP reduction higher than 20%, or the decrease of at least one IOP-lowering medication, was considered a successful outcome. The same population was analyzed by classifying them in two groups as: glaucoma subtypes and lens status. The baseline spherical equivalent (SE) was also calculated for considering association with the achieved IOP. RESULTS: A total of 86 eyes were included. In most cases, IOP and IOP-lowering medications were decreased with a statistically significant difference (p < 0.0001), and all of them had a successful outcome. The percentage of IOP drop oscillated between 25.9% (open-angle glaucoma sub-group) and 37.5% (pseudoexfoliative glaucoma sub-group), 12 months after surgery. The difference between the groups was not statistically significant (p 0.20 and 0.32 for glaucoma subtypes and lens status, respectively). The Pearson's coefficient obtained was low for the SE and IOP association, at the 12 -month postoperative mark (- 0.009; p < 0.001). CONCLUSIONS: The MP-TSCPC treatment was successful in decreasing IOP and IOP-lowering medications, in different glaucoma subtypes. Differences between groups (glaucoma subtypes, phakic and pseudophakic eyes) were not statistically significant. No association was found between the SE and the IOP achieved value after MS-TSCPC treatment.

Analysis of RNA 5' ends: Phosphate enumeration and cap characterization.

The function and fate of cellular RNAs are often governed by the phosphorylation state at the 5' end or the identity of whatever cap may be present there. Here we describe methods for examining these important 5'-terminal features on any cellular or synthetic RNA of interest that can be detected by Northern blotting. One such method, PABLO, is a splinted ligation assay that makes it possible to accurately quantify the percentage of 5' ends that are monophosphorylated. Another, PACO, is a capping assay that reveals the percentage of 5' ends that are diphosphorylated. A third, boronate gel electrophoresis in conjunction with deoxyribozyme-mediated cleavage, enables different types of caps (e.g., m7Gppp caps versus NAD caps) to be distinguished from one another and the percentage of each to be determined. After completing all three tests, the percentage of 5' ends that are triphosphorylated can be deduced by process of elimination. Together, this battery of assays allows the 5' terminus of an RNA to be profiled in unprecedented detail.

Structural and kinetic insights into stimulation of RppH-dependent RNA degradation by the metabolic enzyme DapF.

Vitally important for controlling gene expression in eukaryotes and prokaryotes, the deprotection of mRNA 5' termini is governed by enzymes whose activity is modulated by interactions with ancillary factors. In Escherichia coli, 5'-end-dependent mRNA degradation begins with the generation of monophosphorylated 5' termini by the RNA pyrophosphohydrolase RppH, which can be stimulated by DapF, a diaminopimelate epimerase involved in amino acid and cell wall biosynthesis. We have determined crystal structures of RppH-DapF complexes and measured rates of RNA deprotection. These studies show that DapF potentiates RppH activity in two ways, depending on the nature of the substrate. Its stimulatory effect on the reactivity of diphosphorylated RNAs, the predominant natural substrates of RppH, requires a substrate long enough to reach DapF in the complex, while the enhanced reactivity of triphosphorylated RNAs appears to involve DapF-induced changes in RppH itself and likewise increases with substrate length. This study provides a basis for understanding the intricate relationship between cellular metabolism and mRNA decay and reveals striking parallels with the stimulation of decapping activity in eukaryotes.

NAD in RNA: unconventional headgear.

Although widely assumed to bear a 5'-terminal triphosphate or monophosphate, recent evidence suggests that the 5' end of bacterial RNA can sometimes bear a modification reminiscent of a eukaryotic cap. A new study has now identified Escherichia coli RNAs that begin with a noncanonical cap resembling the redox cofactor nicotinamide adenine dinucleotide (NAD), as well as a cellular enzyme that can remove it. The biological function of such caps remains to be determined.

Importance of a diphosphorylated intermediate for RppH-dependent RNA degradation.

Deprotection of the 5' end appears to be a universal mechanism for triggering the degradation of mRNA in bacteria and eukaryotes. In Escherichia coli, for example, converting the 5' triphosphate of primary transcripts to a monophosphate accelerates cleavage at internal sites by the endonuclease RNase E. Previous studies have shown that the RNA pyrophosphohydrolase RppH catalyzes this transformation in vitro and generates monophosphorylated decay intermediates in vivo. Recently, we reported that purified E. coli RppH unexpectedly reacts faster with diphosphorylated than with triphosphorylated substrates. By using a novel assay, it was also determined that diphosphorylated mRNA decay intermediates are abundant in wild-type E. coli and that their fractional level increases to almost 100% for representative mRNAs in mutant cells lacking RppH. These findings indicate that the conversion of triphosphorylated to monophosphorylated RNA in E. coli is a stepwise process involving sequential phosphate removal and the transient formation of a diphosphorylated intermediate. The latter RNA phosphorylation state, which was previously unknown in bacteria, now appears to define the preferred biological substrates of E. coli RppH. The enzyme responsible for generating it remains to be identified.

Specificity and evolutionary conservation of the Escherichia coli RNA pyrophosphohydrolase RppH.

Bacterial RNA degradation often begins with conversion of the 5'-terminal triphosphate to a monophosphate by the RNA pyrophosphohydrolase RppH, an event that triggers rapid ribonucleolytic attack. Besides its role as the master regulator of 5'-end-dependent mRNA decay, RppH is important for the ability of pathogenic bacteria to invade host cells, yet little is known about how it chooses its targets. Here, we show that Escherichia coli RppH (EcRppH) requires at least two unpaired nucleotides at the RNA 5' end and prefers three or more such nucleotides. It can tolerate any nucleotide at the first three positions but has a modest preference for A at the 5' terminus and either a G or A at the second position. Mutational analysis has identified EcRppH residues crucial for substrate recognition or catalysis. The promiscuity of EcRppH differentiates it from its Bacillus subtilis counterpart, which has a strict RNA sequence requirement. EcRppH orthologs likely to share its relaxed sequence specificity are widespread in all classes of Proteobacteria, except Deltaproteobacteria, and in flowering plants. By contrast, the phylogenetic range of recognizable B. subtilis RppH orthologs appears to be restricted to the order Bacillales. These findings help to explain the selective influence of RppH on bacterial mRNA decay and show that RppH-dependent degradation has diversified significantly during the course of evolution.

Safety and efficacy of perampanel in children and adults with various epilepsy syndromes: A single-center postmarketing study.

INTRODUCTION: Perampanel is an AMPA receptor antagonist recently approved for the treatment of partial and generalized epilepsies with tonic-clonic seizures as an add-on therapy. METHODS: This single-center postmarketing study retrospectively evaluated the efficacy of perampanel in patients with partial onset and other seizure types, with a special emphasis on its efficacy, safety, and tolerability. RESULTS: Review of medical records revealed that adequate data were available on 101 patients taking perampanel. Fifty-seven patients were female. Sixteen patients were of pediatric age range. The average dose of perampanel was 6.5mg, and average treatment duration was 8.2months. After treatment, median seizure frequency reduction was 50% overall, 50% in children, and 33% in adults; 44% in primary generalized, 38% in secondarily generalized, and 33% in partial seizures. Responder rate (50% seizure frequency reduction) was 51% overall, 63% in children, and 49% in adults; 60% in partial seizures, 43% in secondarily generalized tonic-clonic seizures, 53% in primary generalized tonic-clonic seizures, and 56% in other seizure types. Seizure freedom was attained in 6% of cases. Most common adverse events were sleepiness/fatigue (35%), behavioral problems (30%), and dizziness (22%). Adverse events were correlated with dosage. Average dose was 7.3mg in patients with adverse events vs. 5.5mg in those without adverse events. Patients who developed fatigue, cognitive decline, headaches, and weight gain were more likely to discontinue perampanel than those patients who experienced coordination issues and behavioral problems. CONCLUSIONS: These findings suggest that perampanel is safe, well-tolerated, and effective in treatment of various types of adult and pediatric epilepsy syndromes. Fatigue, cognitive decline, headache and weight gain were the main causes of perampanel discontinuation.

Influence of translation on RppH-dependent mRNA degradation in Escherichia coli.

In Escherichia coli, the endonuclease RNase E can access internal cleavage sites in mRNA either directly or by a 5' end-dependent mechanism in which cleavage is facilitated by prior RppH-catalysed conversion of the 5'-terminal triphosphate to a monophosphate, to which RNase E can bind. The characteristics of transcripts that determine which of these two pathways is primarily responsible for their decay are poorly understood. Here we report the influence of ribosome binding and translocation on each pathway, using yeiP and trxB as model transcripts. Ribosome binding to the translation initiation site impedes degradation by both mechanisms. However, because the effect on the rate of 5' end-independent decay is greater, poor ribosome binding favours degradation by that pathway. Arresting translation elongation with chloramphenicol quickly inhibits RNase E cleavage downstream of the initiation codon but has little or no immediate effect on cleavage upstream of the ribosome binding site. RNase E binding to a monophosphorylated 5' end appears to increase the likelihood of cleavage at sites within the 5' untranslated region. These findings indicate that ribosome binding and translocation can have a major impact on 5' end-dependent mRNA degradation in E. coli and suggest a possible sequence of events that follow pyrophosphate removal.

Differential control of the rate of 5'-end-dependent mRNA degradation in Escherichia coli.

Many Escherichia coli mRNAs are degraded by a 5'-end-dependent mechanism in which RppH-catalyzed conversion of the 5'-terminal triphosphate to a monophosphate triggers rapid endonucleolytic cleavage by RNase E. However, little is understood about what governs the decay rates of these transcripts. We investigated the decay of three such messages--rpsT P1, yfcZ, and ydfG--to characterize the rate-determining step in their degradation. The steady-state ratio of monophosphorylated to triphosphorylated rpsT P1 and yfcZ mRNA indicates that their decay rate is limited by cleavage of the monophosphorylated intermediate, making RNase E critical for their rapid turnover. Conversely, the decay rate of ydfG is limited by generation of the monophosphorylated intermediate; therefore, either RNase E or its less abundant paralog RNase G is sufficient for rapid ydfG degradation. Although all three transcripts are stabilized when RppH is absent, overproducing RppH does not accelerate their decay, nor does RppH overproduction appear to influence the longevity of most other messages that it targets. The failure of excess RppH to hasten rpsT P1 and yfcZ degradation despite increasing the percentage of each that is monophosphorylated is consistent with the observation that pyrophosphate removal is not the rate-limiting step in their decay. In contrast, neither the ydfG decay rate nor the fraction of ydfG transcripts that are monophosphorylated increases when the cellular concentration of RppH is raised, suggesting that, for some RppH targets, the rate of formation of the monophosphorylated intermediate is limited by an ancillary factor or by a step that precedes pyrophosphate removal.

Microbial byproducts determine reproductive fitness of free-living and parasitic nematodes.

Trichuris nematodes reproduce within the microbiota-rich mammalian intestine and lay thousands of eggs daily, facilitating their sustained presence in the environment and hampering eradication efforts. Here, we show that bacterial byproducts facilitate the reproductive development of nematodes. First, we employed a pipeline using the well-characterized, free-living nematode C. elegans to identify microbial factors with conserved roles in nematode reproduction. A screen for E. coli mutants that impair C. elegans fertility identified genes in fatty acid biosynthesis and ethanolamine utilization pathways, including fabH and eutN. Additionally, Trichuris muris eggs displayed defective hatching in the presence of fabH- or eutN-deficient E. coli due to reduced arginine or elevated aldehydes, respectively. T. muris reared in gnotobiotic mice colonized with these E. coli mutants displayed morphological defects and failed to lay viable eggs. These findings indicate that microbial byproducts mediate evolutionarily conserved transkingdom interactions that impact the reproductive fitness of distantly related nematodes.

Cognitive and behavioral functioning in Coffin-Siris syndrome and epilepsy: a case presentation.

The authors characterized the cognitive, adaptive, and behavioral sequelae of Coffin-Siris (CS) syndrome and epilepsy in a 7.5-year-old child. Little is known about the early neurobehavioral presentation of CS. Clinical features consistent with this genetic anomaly include underdeveloped tips and nails of the fifth fingers, extended infranasal depression, and craniofacial abnormalities. MRI findings often reveal callosal agenesis. The authors conducted a neuropsychological evaluation and obtained parental ratings of behavioral and adaptive functioning. Attentional abilities were limited. As assessed by the Mullen Scales of Early Learning, receptive language abilities (age equivalent [AE]: 3-3) were relatively stronger than expressive skills (AE: 1-4). Adaptive functioning was low across all domains (Vineland Adaptive Behavior Composite AE: 1-9). On the Behavior Assessment for Children (BASC-2), social skills dysfunction, stereotyped and self-stimulatory behaviors, restricted interests, ritualistic play, and inappropriate object usage were noted. No significant mood disturbances were endorsed. Study findings indicate a diffuse pattern of neurobehavioral deficits in a child with CS and epilepsy. Further clinical assessment and research should include multidimensional assessment techniques, including evaluation of adaptive behavior, in an effort to capture the full range developmental sequelae in children with CS.

CP110 cooperates with two calcium-binding proteins to regulate cytokinesis and genome stability.

The centrosome is an integral component of the eukaryotic cell cycle machinery, yet very few centrosomal proteins have been fully characterized to date. We have undertaken a series of biochemical and RNA interference (RNAi) studies to elucidate a role for CP110 in the centrosome cycle. Using a combination of yeast two-hybrid screens and biochemical analyses, we report that CP110 interacts with two different Ca2+-binding proteins, calmodulin (CaM) and centrin, in vivo. In vitro binding experiments reveal a direct, robust interaction between CP110 and CaM and the existence of multiple high-affinity CaM-binding domains in CP110. Native CP110 exists in large (approximately 300 kDa to 3 MDa) complexes that contain both centrin and CaM. We investigated a role for CP110 in CaM-mediated events using RNAi and show that its depletion leads to a failure at a late stage of cytokinesis and the formation of binucleate cells, mirroring the defects resulting from ablation of either CaM or centrin function. Importantly, expression of a CP110 mutant unable to bind CaM also promotes cytokinesis failure and binucleate cell formation. Taken together, our data demonstrate a functional role for CaM binding to CP110 and suggest that CP110 cooperates with CaM and centrin to regulate progression through cytokinesis.

Race/ethnicity, sex, and socioeconomic status as predictors of outcome after surgery for temporal lobe epilepsy.

BACKGROUND: Several risk factors have been attributed to seizure recurrence after surgery. It is unknown whether race/ethnicity plays a role in outcome. OBJECTIVE: To evaluate whether race/ethnicity plays a role in seizure recurrence after surgery. DESIGN: Cohort study. SETTING: We evaluated data obtained from the epilepsy centers at the University of Alabama at Birmingham and New York University, New York, NY. PATIENTS: All patients included had a diagnosis of mesial temporal sclerosis and underwent temporal lobectomy. MAIN OUTCOME MEASURES: Occurrence of seizure after surgery was registered 1 year after surgery. We used multiple logistic regression analysis to model the presence of seizure recurrence after surgery and generated odds ratios (ORs) for seizure recurrence after surgery for African American and Hispanic patients relative to white patients. An unadjusted model incorporated only race/ethnicity as the independent variable, and an adjusted model included socioeconomic status, age, duration of epilepsy, education, history of febrile seizures, sex, handedness, lateralization of epileptogenic focus, and number of antiepileptics as the independent variables. RESULTS: Two hundred fifty-two patients underwent surgical treatment with pathological confirmation of mesial temporal sclerosis. No differences were found between racial/ethnic groups in terms of seizure recurrence in any models. For African American patients, the ORs were 0.9 (95% confidence interval [CI], 0.4-2.1) for the unadjusted model and 0.8 (95% CI, 0.3-2.0) for the adjusted model; for Hispanic patients, the ORs were 1.6 (95% CI, 0.8-3.2) for the unadjusted model and 1.1 (95% CI, 0.5-2.6) for the adjusted model, relative to white patients. CONCLUSION: Our data suggest that although sex appears to play a role in the outcomes of surgery for temporal lobe epilepsy, race and socioeconomic status do not.

Aprendizaje profundo: ¿La atención oftalmológica del futuro? / Deep learning - the ophthalmological care of the future?

El aprendizaje profundo es un tipo de inteligencia artificial computarizada que tiene como objetivo entrenar a una computadora para que realice tareas que normalmente realizan los humanos basándose en redes neuronales artificiales. Los avances tecnológicos recientes han demostrado que las redes neuronales artificiales se pueden aplicar a campos como el reconocimiento de voz y audio, la traducción automática, los juegos de mesa, el diseño de fármacos y el análisis de imágenes médicas. El desarrollo de estas técnicas ha sido extremadamente rápido en los últimos años y las redes neuronales artificiales hoy en día superan a los humanos en muchas de estas tareas. Las redes neuronales artificiales se inspiraron en la función de sistemas biológicos como el cerebro y los nodos conectados dentro de estas redes que modelan las neuronas. El principio de tales redes es que están capacitadas con conjuntos de datos donde se conoce la verdad fundamental. Como ejemplo, la red debe estar capacitada para identificar imágenes donde se representa una bicicleta. Esto requiere una gran cantidad de imágenes donde las bicicletas se etiquetan manualmente (la llamada verdad fundamental) que luego son analizadas por la computadora. Si se utilizan suficientes imágenes con bicicleta o sin bicicleta, la red neuronal artificial puede entrenarse para identificar bicicletas en otros conjuntos de imágenes. En las imágenes médicas, los enfoques clásicos incluyen la extracción de características semánticas definidas por expertos humanos o características agonísticas definidas por ecuaciones. Las características semánticas pueden proporcionar una buena especificidad para el diagnóstico de enfermedades, pero pueden diferir entre diferentes médicos dependiendo de su nivel de experiencia, requieren mucho tiempo y son costosas. Las características agonísticas pueden tener una especificidad limitada, pero ofrecen la ventaja de una alta reproducibilidad. El aprendizaje profundo tiene un enfoque diferente. Se requiere un conjunto de datos de entrenamiento donde se conoce la verdad básica, en este caso el diagnóstico. El número de datos necesarios es elevado y, por lo general, se utilizan 100.000 imágenes o más. Una vez que se entrena la red neuronal artificial, se puede aplicar a un conjunto de datos de validación en el que también se conoce el diagnóstico, pero no se informa a la computadora. La salida de la red neuronal artificial es, en el caso más simple, una enfermedad o ninguna enfermedad que pueda compararse con la verdad fundamental. La concordancia con la verdad del terreno se cuantifica utilizando medidas como el área bajo la curva (AUC, puede tomar valores entre 0 y 1, siendo 1 la discriminación perfecta entre salud y enfermedad), especificidad (puede tomar valores entre 0% y 100% y la proporción de negativos reales que se identifican correctamente) y la sensibilidad (puede tomar valores entre 0% y 100% y cuantifica la proporción de positivos reales que se identifican correctamente). Si se requiere una alta sensibilidad o una alta especificidad depende de la enfermedad, la prevalencia de la enfermedad, así como el entorno clínico real donde se debe emplear esta red

Pediatric language mapping: sensitivity of neurostimulation and Wada testing in epilepsy surgery.

PURPOSE: Functional mapping of eloquent cortex with electrical neurostimulation is used both intra- and extraoperatively to tailor resections. In pediatric patients, however, functional mapping studies frequently fail to localize language. Wada testing has also been reported to be less sensitive in children. METHODS: Thirty children (4.7 - 14.9 years) and 18 adult controls (18-59 years) who underwent extraoperative language mapping via implanted subdural electrodes at the NYU Comprehensive Epilepsy Center were included in the study. Ten children and 14 adults underwent preoperative Wada testing. Success of the procedures was defined as the identification of at least one language site by neurostimulation mapping and determination of hemispheric language dominance on the Wada test. RESULTS: In children younger than 10.2 years, cortical stimulation identified language cortex at a lower rate than was seen in children older than 10.2 years and in adults (p<0.05). This threshold, demonstrated by survival and chi2 analysis, was sharply defined in our data set. Additionally, Wada testing was more likely to be successful than was extraoperative mapping in this younger age group (p<0.05). CONCLUSIONS: Analysis of our series demonstrates that language cortex is less likely to be identified in children younger than 10 years, suggesting that alternatives to the current methods of cortical electrical stimulation, particularly the use of preoperative language lateralization, may be required in this age group.

RNA editing of a miRNA precursor.

Micro RNAs comprise a large family of small, functional RNAs with important roles in the regulation of protein coding genes in animals and plants. Here we show that human and mouse miRNA22 precursor molecules are subject to posttranscriptional modification by A-to-I RNA editing in vivo. The observed editing events are predicted to have significant implications for the biogenesis and function of miRNA22 and might point toward a more general role for RNA editing in the regulation of miRNA gene expression.