New insights (and new interrogations) in perinatal arterial ischemic stroke

With an incidence of 1/2800 to 1/5000 live-births, perinatal arterial ischemic stroke is the most frequent form of cerebral infarction in children. About 40% of the children do not have specific symptoms in the neonatal period, and are only recognized later with the emergence of motor impairment, developmental delay, specific cognitive deficiency or seizures. In the remaining 60%, children present with early symptoms, mostly recurrent focal seizures in the first 3 days of life. The diagnosis is easily confirmed by cranial ultrasounds and MRI. Early MRI has both a key role in the diagnosis, dating the injury, but also an important prognostic value to predict the motor outcome of the child. Indeed, although the infarct does not recur, the majority of children show subsequent sequels: cerebral palsy, epilepsy, cognitive or behavioural problems. Finding predictors of outcome regarding these latter concerns (and the way to prevent or alleviate them) is of major interest.The main etiological hypothesis for perinatal AIS is a cerebral embolus, originating from the placenta through the foramen ovale. Most of the established risk factors are indeed either determinants or biomarkers of vasculo-placental pathology. Injury to the cervico-cerebral arteries, giving rise to thrombus/embolus during the birthing process is also suggested. Both placento-embolic and traumatic theories are supported by a few, but well-analysed pathological or arteriographic reports. Nevertheless, their relative frequency, the implication of other mechanisms, and their repercussions to evidence-based preventive strategies remain to be determined. Moreover, the mechanism of stroke in the different groups of newborns with stroke (term vs. preterm; symptomatic neonates vs. those with a delayed presentation) is likely to be different, and there is a need for future studies to assess all populations as different entities. Neonatal supportive care remains important for all infants while there is no evidence for preventive anticoagulant use at present. In an effort to reduce neurological dysfunction, and in adjunction with ongoing physical therapy and pharmacological treatment, new rehabilitative interventions, such as constraint-induced movement therapy and mirror therapy, are increasingly being used

Motor Outcomes After Neonatal Arterial Ischemic Stroke Related to Early MRI Data in a Prospective Study

OBJECTIVE: We aimed to correlate early imaging data with motor outcomes in a large, homogeneous, cohort of infants with neonatal (diagnosed before 29 days of life) arterial ischemic stroke (AIS).METHODS: From a prospective cohort of 100 children with neonatal AIS, we analyzed the MRI studies performed within the 28 first days of life for 80 infants evaluated at 2 years of age. The relationships between infarction location and corticospinal tract (CST) involvement and motor outcomes were studied RESULTS: Seventy-three infarctions involved the middle cerebral artery (MCA) territory. Of those, 50 were superficial infarctions, 5 deep infarctions, and 18 mixed infarctions. The CST was involved in 24 cases. Nineteen patients with MCA infarctions (26% [95% confidence interval: 16%–34%]) developed hemiplegia. Mixed infarctions (P < .0001) and CST involvement (P < .0001) were highly predictive of hemiplegia. In contrast, 88% of children with isolated superficial MCA infarctions did not exhibit impairment. CONCLUSIONS: Accurate prediction of motor outcomes can be obtained from early MRI scans after neonatal AIS. The absence of involvement of the CST resulted in normal motor development in 94% of cases. CST involvement resulted in congenital hemiplegia in 66% of cases

Selectivity via Cooperativity: Preferential Stabilization of the p65/14-3-3 Interaction with Semisynthetic Natural Products

Natural compounds are an important class of potent drug molecules including some retrospectively found to act as stabilizers of protein–protein interactions (PPIs). However, the design of synthetic PPI stabilizers remains an understudied approach. To date, there are limited examples where cooperativity has been utilized to guide the optimization of a PPI stabilizer. The 14-3-3 scaffold proteins provide an excellent platform to explore PPI stabilization because these proteins mediate several hundred PPIs, and a class of natural compounds, the fusicoccanes, are known to stabilize a subset of 14-3-3 protein interactions. 14-3-3 has been reported to negatively regulate the p65 subunit of the NF-κB transcription factor, which qualifies this protein complex as a potential target for drug discovery to control cell proliferation. Here, we report the high-resolution crystal structures of two 14-3-3 binding motifs of p65 in complex with 14-3-3. A semisynthetic natural product derivative, DP-005, binds to an interface pocket of the p65/14-3-3 complex and concomitantly stabilizes it. Cooperativity analyses of this interaction, and other disease relevant 14-3-3-PPIs, demonstrated selectivity of DP-005 for the p65/14-3-3 complex. The adaptation of a cooperative binding model provided a general approach to characterize stabilization and to assay for selectivity of PPI stabilizers

Obstetrical and neonatal characteristics vary with birthweight in a cohort of 100 term newborns with symptomatic arterial ischemic stroke

ObjectivesMany questions remain regarding the mechanism of perinatal stroke. Methods In a series of 100 prospectively enrolled term neonates with symptomatic arterial ischemic stroke, we explored family antecedents, pregnancy and delivery conditions and clinical presenting features and distinguished features of the 50 larger infants with the remainder. Cardiac and cervical arterial imaging were performed in 70 and 51 cases. Results Previous fetal loss, first pregnancy, primiparity, twin-gestation, cesarean and traumatic delivery, neonatal distress, male sex and premature rupture of membranes were statistically more common than in the general population. Normal pregnancy proportion and mean birthweight were in the normal range, arguing against a vasculo-placental origin in the majority. Furthermore, there was an excess of large babies. The larger infants were more subject to suffer from acute perinatal events, with a trend for an excess of neonatal distress (p = 0.065) and for more severe presenting features (p = 0.027), while the lighter were more likely to have experienced longstanding obstetrical risk factors such as complicated pregnancy (p = 0.047) and tobacco exposure (p = 0.028). Cervical MR angiography showed an internal carotid occlusion in two babies, whereas echo-Doppler was always normal; in one case the two methods were discordant. Echocardiography was non-informative. Interpretation The data from this prospective cohort of neonates with stroke confirm that many obstetrical and perinatal factors are risk determinants. They also suggest that birthweight and gender may be biomarkers of two populations of neonates with different pathological mechanisms. MR angiography appears more sensitive than echo-Doppler for the exploration of the neonatal cervical vasculature

Assigning Backbone NMR Resonances for Full Length Tau Isoforms: Efficient Compromise between Manual Assignments and Reduced Dimensionality

Tau protein is the longest disordered protein for which nearly complete backbone NMR resonance assignments have been reported. Full-length tau protein was initially assigned using a laborious combination of bootstrapping assignments from shorter tau fragments and conventional triple resonance NMR experiments. Subsequently it was reported that assignments of comparable quality could be obtained in a fully automated fashion from data obtained using reduced dimensionality NMR (RDNMR) experiments employing a large number of indirect dimensions. Although the latter strategy offers many advantages, it presents some difficulties if manual intervention, confirmation, or correction of the assignments is desirable, as may often be the case for long disordered and degenerate polypeptide sequences. Here we demonstrate that nearly complete backbone resonance assignments for full-length tau isoforms can be obtained without resorting either to bootstrapping from smaller fragments or to very high dimensionality experiments and automation. Instead, a set of RDNMR triple resonance experiments of modest dimensionality lend themselves readily to efficient and unambiguous manual assignments. An analysis of the backbone chemical shifts obtained in this fashion indicates several regions in full length tau with a notable propensity for helical or strand-like structure that are in good agreement with previous observations

DEB025 (Alisporivir) Inhibits Hepatitis C Virus Replication by Preventing a Cyclophilin A Induced Cis-Trans Isomerisation in Domain II of NS5A

DEB025/Debio 025 (Alisporivir) is a cyclophilin (Cyp)-binding molecule with potent anti-hepatitis C virus (HCV) activity both in vitro and in vivo. It is currently being evaluated in phase II clinical trials. DEB025 binds to CypA, a peptidyl-prolyl cis-trans isomerase which is a crucial cofactor for HCV replication. Here we report that it was very difficult to select resistant replicons (genotype 1b) to DEB025, requiring an average of 20 weeks (four independent experiments), compared to the typically <2 weeks with protease or polymerase inhibitors. This indicates a high genetic barrier to resistance for DEB025. Mutation D320E in NS5A was the only mutation consistently selected in the replicon genome. This mutation alone conferred a low-level (3.9-fold) resistance. Replacing the NS5A gene (but not the NS5B gene) from the wild type (WT) genome with the corresponding sequence from the DEB025res replicon resulted in transfer of resistance. Cross-resistance with cyclosporine A (CsA) was observed, whereas NS3 protease and NS5B polymerase inhibitors retained WT-activity against DEB025res replicons. Unlike WT, DEB025res replicon replicated efficiently in CypA knock down cells. However, DEB025 disrupted the interaction between CypA and NS5A regardless of whether the NS5A protein was derived from WT or DEB025res replicon. NMR titration experiments with peptides derived from the WT or the DEB025res domain II of NS5A corroborated this observation in a quantitative manner. Interestingly, comparative NMR studies on two 20-mer NS5A peptides that contain D320 or E320 revealed a shift in population between the major and minor conformers. These data suggest that D320E conferred low-level resistance to DEB025 probably by reducing the need for CypA-dependent isomerisation of NS5A. Prolonged DEB025 treatment and multiple genotypic changes may be necessary to generate significant resistance to DEB025, underlying the high barrier to resistance

A metodologia de Lamarck

Neste artigo, o método científico de Jean-Baptiste Lamarck é estudado sob o ponto de vista de seu discurso metodológico, bem como sob o ponto de vista de sua prática científica. Essa metodologia é comparada à preconizada por Condillac, assim como à dos "ideólogos" (idéologues) grupo no qual se costuma incluir o próprio Lamarck. Mostra-se que o discurso metodológico de Lamarck assemelha-se ao dos ideólogos; no entanto, sua prática científica não se coaduna com esse enfoque. Em vez de seguir uma abordagem empirista, a obra de Lamarck se fundamenta em princípios metafísicos gerais sobre a natureza. Sob o ponto de vista dos ideólogos, seu trabalho deveria ser rejeitado - o que de fato ocorreu - como um mero sistema (système) metafísico - no sentido pejorativo utilizado pelos seguidores de Condillac. No entanto, o presente artigo argumenta que esse é justamente um importante e inovador aspecto da obra de Lamarck, que permitiu a eclosão do evolucionismo moderno

Inverted Pyramidal Neurons and Their Axons in the Neocortex of Reeler Mutant Mice

Inverted pyramidal neurons are very abundant in the cerebral cortex of the adult reeler mutant mouse. Two types of inverted pyramid are found in rapid Golgi impregnations. In the first type the axon starts from the base of the cell body and bends towards the white matter. In the second type, which is more common, the axon emerges from the apical dendritic tree and descends directly towards the white matter. Despite its abnormal topography, the site of origin of the axon in pyramids of the second type displays a normal differentiation, when analysed with the electron microscopic Golgi technique, suggesting that the ectopic initial axon segment is able to fulfil its normal functions