Neurite outgrowth is influenced by positive and negative signals that include the semaphorins, an important family of axonal outgrowth inhibitors. Here we report that the Rac GTPase activating protein (GAP) ␣2-chimaerin is involved in Semaphorin 3A (Sema 3A) signaling. In dorsal root ganglion neurons, Sema 3A-induced growth cone collapse was inhibited by ␣2-chimaerin mutated to eliminate GAP activity or interaction with phosphotyrosine. Activation of ␣2-chimaerin by phorbol ester caused growth cone collapse. Active ␣2-chimaerin interacts with collapsin response mediator protein-2 (CRMP-2) and cyclin-dependent kinase (Cdk) 5/p35 kinase through its SH2 and GAP domains, respectively. Cdk5 phosphorylates CRMP-2 at serine 522, possibly facilitating phosphorylation of serine 518 and threonine 514 by glycogen synthase kinase 3 (GSK3), a kinase previously implicated in Sema 3A signaling. Phosphorylation of CRMP-2 serine 522 was essential for Sema 3A-induced growth cone collapse, which is dependent on Cdk5 but not Rho kinase activity. ␣2-chimaerin, like CRMP-2, can associate with the Sema 3A receptor. These results indicate that active ␣2-chimaerin Rac GAP, Cdk5/p35, and its substrate CRMP-2, are implicated in the dynamics of growth cone guidance initiated through Sema 3A signaling.
AimsThe objective of the study was to evaluate the pharmacokinetics (and how they are affected by food), CNS pharmacodynamics and the adverse event profile of brivaracetam after single increasing doses. MethodsHealthy males (n = 27, divided into three alternating panels of nine subjects) received two different single oral doses of brivaracetam (10-1400 mg) and one dose of placebo during three periods of a randomized, double-blind, placebo-controlled study. The effect of food on its pharmacokinetics was assessed using a standard two-way crossover design in a further eight subjects who received two single oral doses of brivaracetam (150 mg) in the fasting state and after a high fat meal. ResultsAdverse events, none of which were serious, were mostly CNS-related and included somnolence, dizziness, and decreased attention, alertness, and motor control. Their incidence, severity and duration were dose-related. The maximum tolerated dose was established to be 1000 mg. Severe somnolence lasting 1 day occurred in one subject following 1400 mg. Brivaracetam was rapidly absorbed under fasting conditions, with a median tmax of approximately 1 h. Cmax was dose-proportional from 10 to1400 mg, whereas AUC deviated from dose linearity above 600 mg. A high-fat meal had no effect on AUC (point estimate 0.99, 90%CI: 0.92-1.07) but delayed tmax (3 h) and decreased Cmax (point estimate 0.72, 90%CI: 0.66-0.79). ConclusionsBrivaracetam was well tolerated after increasing single doses that represent up to several times the expected therapeutic dose. Brivaracetam was found to have desirable pharmacokinetic properties. The most common adverse events were somnolence and dizziness.
OXC adjunctive therapy administered in a dose range of 6 to 51 mg/kg/day (median 31.4 mg/kg/day) is safe, effective, and well tolerated in children with partial seizures.
Neuronal differentiation involves Rac and Cdc42 GTPases. ␣-Chimaerin, a Rac/Cdc42 regulator, occurs as ␣1-and alternatively spliced Src homology 2 (SH2) domain-containing ␣2-isoforms. ␣2-chimaerin mRNA was highly expressed in the rat embryonic nervous system, especially in early postmitotic neurons. ␣1-chimaerin mRNA was undetectable before embryonic day 16.5. Adult ␣2-chimaerin mRNA was restricted to neurons within specific brain regions, with highest expression in the entorhinal cortex. ␣2-chimaerin protein localized to neuronal perikarya, dendrites, and axons. The overall pattern of ␣2-chimaerin mRNA expression resembles that of cyclindependent kinase regulator p35 (CDK5/p35) which participates in neuronal differentiation and with which chimaerin interacts. To determine whether ␣2-chimaerin may have a role in neuronal differentiation and the relevance of the SH2 domain, the morphological effects of both chimaerin isoforms were investigated in N1E-115 neuroblastoma cells. When plated on poly-lysine, transient ␣2-chimaerin but not ␣1-chimaerin transfectants formed neurites. Permanent ␣2-chimaerin transfectants generated neurites whether or not they were stimulated by serum starvation, and many cells were enlarged. Permanent ␣1-chimaerin transfectants displayed numerous microspikes and contained F-actin clusters, a Cdc42-phenotype, but generated few neurites. In neuroblastoma cells, ␣2-chimaerin was predominantly soluble with some being membrane-associated, whereas ␣1-chimaerin was absent from the cytosol, being membrane-and cytoskeleton-associated, paralleling their subcellular distribution in brain. Transient transfection with ␣2-chimaerin mutated in the SH2 domain (N94H) generated an ␣1-chimaerin-like phenotype, protein partitioned in the particulate fraction, and in NGF-stimulated pheochromocytoma cell line 12 (PC12) cells, neurite formation was inhibited. These results indicate a role for ␣2-chimaerin in morphological differentiation for which its SH2 domain is vital.
Background Many low- and middle-income countries (LMIC) are moving towards enforcing prescription-only access to antibiotics. This systematic literature review aims to assess the interventions used to enforce existing legislation prohibiting over-the-counter (OTC) sales of antibiotics in LMICs, their impact and examine the methods chosen for impact measurement including their strengths and weaknesses. Methods Both PubMed and Embase were systematically searched for studies reporting on impact measurement in moving towards prescription only access to antibiotics in LMICs. The PRISMA methodological review framework was used to ensure systematic data collection and analysis of literature. Narrative data synthesis was used due to heterogeneity of study designs. Results In total, 15 studies were included that assessed policy impact in 10 different countries. Strategies employed to enforce regulations prohibiting OTC sales of systemic antibiotics included retention of prescriptions for antibiotics by pharmacies, government inspections, engaging pharmacists in the design of interventions, media campaigns for the general public and educational activities for health care workers. A variety of outcomes was used to assess the policy impact; changes in antimicrobial resistance rates, changes in levels of antibiotic use, changes in trends of antibiotic use, changes in OTC supply of antibiotics, and changes in reported practices and knowledge of pharmacists, medicine sellers and the general public. Differences in methodological approaches and outcome assessment made it difficult to compare the effectiveness of law enforcement activities. Most effective appeared to be multifaceted approaches that involved all stakeholders. Monitoring of the impact on total sales of antibiotics by means of an interrupted time series (ITS) analysis and analysis of pharmacies selling antibiotics OTC using mystery clients were the methodologically strongest designs used. Conclusions The published literature describing activities to enforce prescription-only access to antibiotics in LMICs is sparse and offers limited guidance. Most likely to be effective are comprehensive multifaceted interventions targeting all stakeholders with regular reinforcement of messages. Policy evaluation should be planned as part of implementation to assess the impact and effectiveness of intervention strategies and to identify targets for further activities. Robust study designs such as ITS analyses and mystery client surveys should be used to monitor policy impact. Electronic supplementary material The online version of this article (10.1186/s12913-019-4359-8) contains supplementary material, which is available to authorized users.
In the developing forebrain, neuronal polarization is a stepwise and initially reversible process that underlies correct migration and axon specification. Many aspects of cytoskeletal changes that accompany polarization are currently molecularly undefined and thus poorly understood. Here we reveal that the p21-activated kinase (Pak1) is essential for the specification of an axon and dendrites. In hippocampal neurons, activation of Pak1 is spatially restricted to the immature axon despite its uniform presence in all neurites. Hyperactivation of Pak1 at the membrane of all neurites or loss of Pak1 expression disrupts both neuronal morphology and the distinction between an axon and dendrites. We reveal that Pak1 acts on polarity in a kinase-dependent manner, by affecting the F-actin and microtubule cytoskeleton at least in part through Rac1 and cofilin. Our data are the first to demonstrate the importance of localized Pak1 kinase activation for neuronal polarization and differentiation.
Much research focuses on producing maximal intervention effects. This has generally not resulted in interventions being rapidly or widely adopted or seen as feasible given resources, time, and expertise constraints in the majority of real-world settings. We present a definition and key characteristics of a minimum intervention needed to produce change (MINC). To illustrate use of a MINC condition, we describe a computer-assisted, interactive minimal intervention, titled Healthy Habits, used in three different controlled studies and its effects. This minimal intervention produced modest to sizable health behavior and psychosocial improvements, depending on the intensity of personal contacts, producing larger effects at longer-term assessments. MINC comparison conditions could help to advance both health care and health research, especially comparative effectiveness research. Policy and funding implications of requiring an intervention to be demonstrated more effective than a simpler, less costly MINC alternative are discussed.
Our findings show that brivaracetam clearly suppresses generalized photoparoxysmal EEG response. As such, investigations of the antiepileptic properties and tolerability of brivaracetam are warranted in further clinical studies of patients with epilepsy.
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