Cellular Dynamics during Spinal Cord Regeneration in Larval Zebrafish.

The study of spinal cord regeneration using diverse animal models, which range from null to robust regenerative capabilities, is imperative for understanding how regeneration evolved and, eventually, to treat spinal cord injury and paralysis in humans. In this study, we used electroablation to fully transect the spinal cord of zebrafish larvae (3 days postfertilization) and examined regeneration of the tissue over time. We used transgenic lines to follow immune cells, oligodendrocytes, and neurons in vivo during the entire regenerative process. We observed that immune cells are recruited to the injury site, oligodendrocytes progenitor cells (olig2-expressing cells) invade, and axons cross the gap generated upon damage from anterior to reinnervate caudal structures. Together with the recovery of cell types and structures, a complete reversal of paralysis was observed in the lesioned larvae indicating functional regeneration. Finally, using transplantation to obtain mosaic larvae with single-labeled neurons, we show that severed spinal axons exhibited varying regenerative capabilities and plasticity depending on their original dorsoventral position in the spinal cord.

Acute Hemorrhagic Edema of Infancy: Still a Challenge for the Pediatrician.

We report a case of acute hemorrhagic edema of infancy (AHEI) occurred in an 11-month-old male infant after upper respiratory tract infection. The onset was dramatic with petechiae, ecchymosis, and annular, nummular, or targetoid purpuric plaques on the extremities, face, and ears. Acute hemorrhagic edema of infancy is a benign form of leukocytoclastic vasculitis that typically affects children between 4 and 24 months of age. The etiology remains still unknown. The potential triggers of AHEI include preceding bacterial or viral infections, immunizations, and drugs. Although the clinical picture is fearful, in the majority of cases, it involves only cutaneous small vessels. Recognizing this as a distinct clinical entity allows to establish an appropriate prognosis for this rare benign disease in children.This report could be a helpful reminder, especially for emergency physicians, to discriminate AHEI from other more severe diseases, such as meningococcal sepsis.

Low synovial double negative T and γδ T cells predict longer free-disease survival in oligoarticular JIA.

BACKGROUND: Oligoarticular juvenile idiopathic arthritis (oJIA) is the most frequent form of chronic arthritis in children; the clinical course is extremely variable. In this study we have characterized by flow cytometry synovial B and T cells subsets in patients with oJIA in order to identify any parameters that could predict a more aggressive course of disease. METHODS: B and T cells from synovial fluid (SF) of 39 patients with oJIA were characterized by flow cytometry. In 22 patients SF was analysed at the onset of the disease (GroupA), in 17 SF was analysed at articular relapse (Group B). All patients in Group A were followed up for at least for 2 years after SF analysis: 13 patients relapsed during the follow-up period. RESULTS: Comparison of SF from Group A and Group B demonstrated an activated phenotype in relapsed patients, with higher Switched Memory B cells (58.53 vs 36.07% of CD19+, P-value 0.004) and lower Naïve B cells (8.53 vs 25.9 of CD19+, P-value 0.002) in Group B. Furthermore, patients from Group A who did not relapse showed lower percentages of synovial DNT (2.38 vs 1.50% of CD3 + TCRalpha/beta+, P-value 0.025) and γδ T cells (19.1 vs 15.0% of CD3+ cells, P-value 0.004) at the onset, if compared with other Group A patients. CONCLUSIONS: In oJIA relapse SF present an activated B phenotype. Patients at disease onset with DNTs <1.8% and/or γδ T cells <16% of CD3+ in synovial fluid have longer free-disease survival. © 2017 International Clinical Cytometry Society.

Loss of Mgat5a-mediated N-glycosylation stimulates regeneration in zebrafish.

BACKGROUND: We are using genetics to identify genes specifically involved in hearing regeneration. In a large-scale genetic screening, we identified mgat5a, a gene in the N-glycosylation biosynthesis pathway whose activity negatively impacts hair cell regeneration. METHODS: We used a combination of mutant analysis in zebrafish and a hair cell regeneration assay to phenotype the loss of Mgat5a activity in zebrafish. We used pharmacological inhibition of N-glycosylation by swansonine. We also used over-expression analysis by mRNA injections to demonstrate how changes in N-glycosylation can alter cell signaling. RESULTS: We found that mgat5a was expressed in multiple tissues during zebrafish embryo development, particularly enriched in neural tissues including the brain, retina, and lateral line neuromasts. An mgat5a insertional mutation and a CRISPR/Cas9-generated truncation mutation both caused an enhancement of hair cell regeneration which could be phenocopied by pharmacological inhibition with swansonine. In addition to hair cell regeneration, inhibition of the N-glycosylation pathway also enhanced the regeneration of lateral line axon and caudal fins. Further analysis showed that N-glycosylation altered the responsiveness of TGF-beta signaling. CONCLUSIONS: The findings from this study provide experimental evidence for the involvement of N-glycosylation in tissue regeneration and cell signaling.

Mechanosensory organ regeneration in zebrafish depends on a population of multipotent progenitor cells kept latent by Schwann cells.

BACKGROUND: Regenerating damaged tissue is a complex process, requiring progenitor cells that must be stimulated to undergo proliferation, differentiation and, often, migratory behaviors and morphological changes. Multiple cell types, both resident within the damaged tissue and recruited to the lesion site, have been shown to participate. However, the cellular and molecular mechanisms involved in the activation of progenitor cell proliferation and differentiation after injury, and their regulation by different cells types, are not fully understood. The zebrafish lateral line is a suitable system to study regeneration because most of its components are fully restored after damage. The posterior lateral line (PLL) is a mechanosensory system that develops embryonically and is initially composed of seven to eight neuromasts distributed along the trunk and tail, connected by a continuous stripe of interneuromastic cells (INCs). The INCs remain in a quiescent state owing to the presence of underlying Schwann cells. They become activated during development to form intercalary neuromasts. However, no studies have described if INCs can participate in a regenerative event, for example, after the total loss of a neuromast. RESULTS: We used electroablation in transgenic larvae expressing fluorescent proteins in PLL components to completely ablate single neuromasts in larvae and adult fish. This injury results in discontinuity of the INCs, Schwann cells, and the PLL nerve. In vivo imaging showed that the INCs fill the gap left after the injury and can regenerate a new neuromast in the injury zone. Further, a single INC is able to divide and form all cell types in a regenerated neuromast and, during this process, it transiently expresses the sox2 gene, a neural progenitor cell marker. We demonstrate a critical role for Schwann cells as negative regulators of INC proliferation and neuromast regeneration, and that this inhibitory property is completely dependent on active ErbB signaling. CONCLUSIONS: The potential to regenerate a neuromast after damage requires that progenitor cells (INCs) be temporarily released from an inhibitory signal produced by nearby Schwann cells. This simple yet highly effective two-component niche offers the animal robust mechanisms for organ growth and regeneration, which can be sustained throughout life.

Axon-Schwann cell interactions during peripheral nerve regeneration in zebrafish larvae.

BACKGROUND: Peripheral nerve injuries can severely affect the way that animals perceive signals from the surrounding environment. While damage to peripheral axons generally has a better outcome than injuries to central nervous system axons, it is currently unknown how neurons re-establish their target innervations to recover function after injury, and how accessory cells contribute to this task. Here we use a simple technique to create reproducible and localized injury in the posterior lateral line (pLL) nerve of zebrafish and follow the fate of both neurons and Schwann cells. RESULTS: Using pLL single axon labeling by transient transgene expression, as well as transplantation of glial precursor cells in zebrafish larvae, we individualize different components in this system and characterize their cellular behaviors during the regenerative process. Neurectomy is followed by loss of Schwann cell differentiation markers that is reverted after nerve regrowth. We show that reinnervation of lateral line hair cells in neuromasts during pLL nerve regeneration is a highly dynamic process with promiscuous yet non-random target recognition. Furthermore, Schwann cells are required for directional extension and fasciculation of the regenerating nerve. We provide evidence that these cells and regrowing axons are mutually dependant during early stages of nerve regeneration in the pLL. The role of ErbB signaling in this context is also explored. CONCLUSION: The accessibility of the pLL nerve and the availability of transgenic lines that label this structure and their synaptic targets provides an outstanding in vivo model to study the different events associated with axonal extension, target reinnervation, and the complex cellular interactions between glial cells and injured axons during nerve regeneration.

The embryonic septum and ventral pallium, new sources of olfactory cortex cells.

The mammalian olfactory cortex is a complex structure located along the rostro-caudal extension of the ventrolateral prosencephalon, which is divided into several anatomically and functionally distinct areas: the anterior olfactory nucleus, piriform cortex, olfactory tubercle, amygdaloid olfactory nuclei, and the more caudal entorhinal cortex. Multiple forebrain progenitor domains contribute to the cellular diversity of the olfactory cortex, which is invaded simultaneously by cells originating in distinct germinal areas in the dorsal and ventral forebrain. Using a combination of dye labeling techniques, we identified two novel areas that contribute cells to the developing olfactory cortices, the septum and the ventral pallium, from which cells migrate along a radial and then a tangential path. We characterized these cell populations by comparing their expression of calretinin, calbindin, reelin and Tbr1 with that of other olfactory cell populations.

The influence of the environment on Cajal-Retzius cell migration.

During cerebral cortex development, different cell populations migrate tangentially through the preplate, traveling from their site of origin toward their final positions. One of the earliest populations formed, the Cajal-Retzius (C-R) cells, is mainly generated in different cortical hem (CH) domains, and they migrate along established and parallel routes to cover the whole cortical mantle. In this study, we present evidence that the phenotype of -Retzius cells, as well as some of their migratory characteristics, is specified in the area where the cells are generated. Nevertheless, when implanted ectopically, these cells can follow new migratory routes, indicating that locally provided genetic cues along the migratory path nonautonomously influence the position of these cells emanating from different portions of the CH. This was witnessed by performing CH implants of tissue expressing fluorescent tracers in live whole embryos. In the same way, tracer injections into the hem of Small eye mutant mice were particularly informative since the lack of Pax6 affects some guidance factors in the migratory environment. As a result, in these animals, the C-R cell population is disorganized, and it forms 1 day late, showing certain differences in gene expression that might help explain these disruptions.

Percepção auditiva e suas implicações para o desenvolvimento global e de linguagem em crianças com síndrome de down / Hearing perception and its implications for language and global development in down syndrome children

Crianças com síndrome de Down (SD) são altamente suscetíveis a perda auditiva. Estudos independentes também apontam atraso de desenvolvimento maior em linguagem do que em outras áreas. O objetivo deste trabalho foi o de verificar a incidência concomitante de perda auditiva e de atraso de desenvolvimento geral e de linguagem neste grupo, nos primeiros anos de vida. Foram estudadas 51 crianças de 6 a 47 meses, das quais 22 com SD, 13 sem atraso de desenvolvimento como grupo-controle normal (CN) e 16 com deficiência mental devida a outras etiologias como segundo grupo controle (COE). As crianças, sem indicação de perda auditiva em seus prontuários, foram submetidas a um protocolo que incluiu avaliação audiométrica e de desenvolvimento psicológico. As crianças com deficiência mental nos dois grupos (SD e COE) apresentaram limiares auditivos mais altos que as crianças do grupo CN e a elevação de limiar no grupo SD foi maior para todas as freqüências testadas. Os escores Z foram mais baixos no grupo SD para desenvolvimento de linguagem, e no grupo COE para desenvolvimento mental e psicomotor. Limiares auditivos mais elevados se correlacionaram com níveis mais inferiores de desenvolvimento no grupo SD. São discutidas estratégias de monitoramento clinico intenso, e de intervenção terapêutica, com vistas a preservação da audição e conseqüente melhoria na qualidade de desenvolvimento de crianças com SD (AU)

Polifonia em recontos infantis

Este trabalho faz parte de um estudo desenvolvido em minha dissertacao de mestrado, no qual pude discutir, pela analise de recontos infantis, a presenca do outro na construcao do sentido. O corpus constituiu-se de recontos (textos orais) produzidos por criancas em idade pre-escolar a partir de uma Oficina de Leitura. Perseguindo as formas do discurso relatado, procuramos, no campo dos estudos enunciativos, produzir uma reflexao sobre as formas de representacao do discurso relatado nos recontos infantis, explicitando a multiplicidade e ambiguidade de vozes presentes no enunciado. As caracteristicas do discurso oral nos fizeram repensar os espacos fronteiricos entre um dizer e outro. Ao mesmo tempo em que o conceito de polifonia, na perspectiva ducrotiana, apresentou-se como um ponto de partida produtivo para nossas reflexoes, impos-se como um limite que nos motivou a avancar para uma perspectiva discursiva. Por essa via de analise foi-nos possivel apontar para a heterogeneidade do sujeito e do discurso e para a incompletude necessaria na constituicao desse sujeito (Orlandi, 1988).

Deficiência auditiva na criança / Hearing deficiency in child

Num total de 3.106 casos examinados no Centro Audiológico do CEAL - Centro Educacional da Audiçäo e Linguagem "Ludovico Pavoni", em Brasília, DF, no período de 1§ de janeiro de 1982 a 31 de dezembro de 1983, foram selecionados e analisados 1.215 casos, na faixa etária de zero a 15 anos, dos quais 782 com deficiência auditiva, procedentes do DF e de alguns Estados, tais como: Goiás, Bahia, Mato Grosso, Pará, Piauí, Minas Gerais, Maranhäo, Amazonas e Rondônia. As seguintes variáveis foram estudadas em tabelas de freqüência simples: grau de deficiência (leve, moderada, severa e profunda); tipo de deficiência (condutiva, neuro-sensorial e mista); faixa etária (de zero a 15 anos); sexo (feminino e masculino); causas (pré, neo e pós-natal); e origem do paciente. Os principais resultados foram: 1) A principal causa pré-natal continua sendo a hereditariedade, onde a consangüinidade contribui com 53,75%, aproximadamente, continuando a rubéola em segundo lugar com 29,85%. Dentre as causas neonatais temos a prematuridade contribuindo com 57,90%. Observamos, ainda, que as viroses, como o sarampo e a parotidite, continuam a ser causas significativas pós-natais, levando a disacusia neuro-sensorial, com 25,00% e 16,70%, respectivamente. A meningite continua a ser causa predominante de surdez pós-natal (33,03%), inclusive aumentando sua freqüência em relaçäo a trabalho nosso anterior. Crescendo significativa e perigosamente (22,32%) o uso de ototóxicos. Observamos ainda que os problemas condutivos...