Perspectives on Mechanisms Supporting Neuronal Polarity From Small Animals to Humans.

Axon-dendrite formation is a crucial milestone in the life history of neurons. During this process, historically referred as "the establishment of polarity," newborn neurons undergo biochemical, morphological and functional transformations to generate the axonal and dendritic domains, which are the basis of neuronal wiring and connectivity. Since the implementation of primary cultures of rat hippocampal neurons by Gary Banker and Max Cowan in 1977, the community of neurobiologists has made significant achievements in decoding signals that trigger axo-dendritic specification. External and internal cues able to switch on/off signaling pathways controlling gene expression, protein stability, the assembly of the polarity complex (i.e., PAR3-PAR6-aPKC), cytoskeleton remodeling and vesicle trafficking contribute to shape the morphology of neurons. Currently, the culture of hippocampal neurons coexists with alternative model systems to study neuronal polarization in several species, from single-cell to whole-organisms. For instance, in vivo approaches using C. elegans and D. melanogaster, as well as in situ imaging in rodents, have refined our knowledge by incorporating new variables in the polarity equation, such as the influence of the tissue, glia-neuron interactions and three-dimensional development. Nowadays, we have the unique opportunity of studying neurons differentiated from human induced pluripotent stem cells (hiPSCs), and test hypotheses previously originated in small animals and propose new ones perhaps specific for humans. Thus, this article will attempt to review critical mechanisms controlling polarization compiled over decades, highlighting points to be considered in new experimental systems, such as hiPSC neurons and human brain organoids.

Testosterone activates glucose metabolism through AMPK and androgen signaling in cardiomyocyte hypertrophy.

BACKGROUND: Testosterone regulates nutrient and energy balance to maintain protein synthesis and metabolism in cardiomyocytes, but supraphysiological concentrations induce cardiac hypertrophy. Previously, we determined that testosterone increased glucose uptake-via AMP-activated protein kinase (AMPK)-after acute treatment in cardiomyocytes. However, whether elevated glucose uptake is involved in long-term changes of glucose metabolism or is required during cardiomyocyte growth remained unknown. In this study, we hypothesized that glucose uptake and glycolysis increase in testosterone-treated cardiomyocytes through AMPK and androgen receptor (AR). METHODS: Cultured cardiomyocytes were stimulated with 100 nM testosterone for 24 h, and hypertrophy was verified by increased cell size and mRNA levels of ß-myosin heavy chain (ß-mhc). Glucose uptake was assessed by 2-NBDG. Glycolysis and glycolytic capacity were determined by measuring extracellular acidification rate (ECAR). RESULTS: Testosterone induced cardiomyocyte hypertrophy that was accompanied by increased glucose uptake, glycolysis enhancement and upregulated mRNA expression of hexokinase 2. In addition, testosterone increased AMPK phosphorylation (Thr172), while inhibition of both AMPK and AR blocked glycolysis and cardiomyocyte hypertrophy induced by testosterone. Moreover, testosterone supplementation in adult male rats by 5 weeks induced cardiac hypertrophy and upregulated ß-mhc, Hk2 and Pfk2 mRNA levels. CONCLUSION: These results indicate that testosterone stimulates glucose metabolism by activation of AMPK and AR signaling which are critical to induce cardiomyocyte hypertrophy.

New insights on epigenetic mechanisms supporting axonal development: histone marks and miRNAs.

Mechanisms supporting axon growth and the establishment of neuronal polarity have remained largely disconnected from their genetic and epigenetic fundamentals. Recently, post-transcriptional modifications of histones involved in chromatin folding and transcription, and microRNAs controlling translation have emerged as regulators of axonal specification, growth, and guidance. In this article, we review novel evidence supporting the concept that epigenetic mechanisms work at both transcriptional and post-transcriptional levels to shape axons. We also discuss the role of splicing on axonal growth, as one of the most (if not the most) powerful post-transcriptional mechanism to diversify genetic information. Overall, we think exploring the gap between epigenetics and axonal growth raises new questions and perspectives to the development of axons in physiological and pathological contexts.

Clinical and serological profile of asymptomatic and non-severe symptomatic COVID-19 cases: Lessons from a longitudinal study in primary care in Latin America.

BACKGROUND: Chile has one of the highest incidences of COVID-19 infection in the world. Primary care can play a key role in early detection and containment of the disease. There is a lack of information on the clinical profile of patients with suspected COVID-19 in primary care, and controversy on the effectiveness of rapid serologic tests in the diagnosis and surveillance of the disease. AIM: To assess the effectiveness of rapid serologic testing in detection and surveillance of COVID-19 cases in primary care. DESIGN & SETTING: A longitudinal study was undertaken, which was based on a non-random sample of 522 participants, including 304 symptomatic patients and 218 high-risk asymptomatic individuals. They were receiving care at four primary health clinics in an underserved area in Santiago, Chile. METHOD: The participants were systematically assessed and tested for COVID-19 with reverse transcriptase-polymerase chain reaction (RT-PCR) and serology at baseline, and were followed clinically and serologically for 3 weeks. RESULTS: The prevalence rate of RT-PCR confirmed COVID-19 cases were 3.5 times higher in symptomatic patients (27.5%; 95% confidence interval [CI] = 22.1 to 32.8) compared with asymptomatic participants (7.9%; 95% CI = 4.3 to 11.6). Similarly, the immune response was significantly different between both groups. Sensitivity of serologic testing was 57.8% (95% CI = 44.8 to 70.1) during the third week of follow-up and specificity was 98.4% (95% CI = 95.5 to 99.7). CONCLUSION: Rapid serologic testing is ineffective for detecting asymptomatic or non-severe cases of COVID-19 at early stages of the disease, but can be of value for surveillance of immunity response in primary care. The clinical profile and immune response of patients with COVID-19 in primary care differs from those in hospital-based populations.

Testosterone activates glucose metabolism through AMPK and androgen signaling in cardiomyocyte hypertrophy

BACKGROUND: Testosterone regulates nutrient and energy balance to maintain protein synthesis and metabolism in cardiomyocytes, but supraphysiological concentrations induce cardiac hypertrophy. Previously, we determined that testosterone increased glucose uptake­via AMP-activated protein kinase (AMPK)­after acute treatment in cardiomyocytes. However, whether elevated glucose uptake is involved in long-term changes of glucose metabolism or is required during cardiomyocyte growth remained unknown. In this study, we hypothesized that glucose uptake and glycolysis increase in testosterone-treated cardiomyocytes through AMPK and androgen receptor (AR). METHODS: Cultured cardiomyocytes were stimulated with 100 nM testosterone for 24 h, and hypertrophy was verified by increased cell size and mRNA levels of ß-myosin heavy chain (ß-mhc). Glucose uptake was assessed by 2-NBDG. Glycolysis and glycolytic capacity were determined by measuring extracellular acidification rate (ECAR). RESULTS: Testosterone induced cardiomyocyte hypertrophy that was accompanied by increased glucose uptake, glycolysis enhancement and upregulated mRNA expression of hexokinase 2. In addition, testosterone increased AMPK phosphorylation (Thr172), while inhibition of both AMPK and AR blocked glycolysis and cardiomyocyte hypertrophy induced by testosterone. Moreover, testosterone supplementation in adult male rats by 5 weeks induced cardiac hypertrophy and upregulated ß-mhc, Hk2 and Pfk2 mRNA levels. CONCLUSION: These results indicate that testosterone stimulates glucose metabolism by activation of AMPK and AR signaling which are critical to induce cardiomyocyte hypertrophy.

Protocol for Evaluating Neuronal Polarity in Murine Models.

The establishment of polarity is crucial for the physiology and wiring of neurons. Therefore, monitoring the axo-dendritic specification allows the mechanisms and signals associated with development, growth, and disease to be explored. Here, we describe major and minor steps to study polarity acquisition, using primary cultures of hippocampal neurons isolated from embryonic rat hippocampi, for in vitro monitoring. Furthermore, we use in utero electroporated, GFP-expressing embryonic mouse brains for visualizing cortical neuron migration and polarization in situ. Some underreported after-protocol steps are also included. For complete details on the use and execution of this protocol, please refer to Wilson et al. (2020).

Fine-Tuning the TGFß Signaling Pathway by SARA During Neuronal Development.

Neural development is a complex process that involves critical events, including cytoskeleton dynamics and selective trafficking of proteins to defined cellular destinations. In this regard, Smad Anchor for Receptor Activation (SARA) is an early endosome resident protein, where perform trafficking- associated functions. In addition, SARA is also involved in cell signaling, including the TGFß-dependent pathway. Accordingly, SARA, and TGFß signaling are required for proper axonal specification and migration of cortical neurons, unveiling a critical role for neuronal development. However, the cooperative action between the TGFß pathway and SARA to this process has remained understudied. In this work, we show novel evidence suggesting a cross-talk between SARA and TGFß pathway needed for proper polarization, axonal specification, growth and cortical migration of central neurons both in vitro and in vivo. Using microscopy tools and cultured hippocampal neurons, we show a local interaction between SARA and TßRI (TGFß I receptor) at endosomes. In addition, SARA loss of function, induced by the expression of the dominant-negative SARA-F728A, over-activates the TGFß pathway, most likely by preserving phosphorylated TßRI. Consequently, SARA-mediated activation of TGFß pathway impacts on neuronal development, promoting axonal growth and cortical migration of neurons during brain development. Moreover, our data suggests that SARA basally prevents the activation of TßRI through the recruitment of the inhibitory complex PP1c/GADD34 in polarizing neurons. Together, these results propose that SARA is a negative regulator of the TGFß pathway, being critical for a proper orchestration for neuronal development.

The Histone Methyltransferase G9a Controls Axon Growth by Targeting the RhoA Signaling Pathway.

The generation of axonal and dendritic domains is critical for brain circuitry assembly and physiology. Negative players, such as the RhoA-Rho coiled-coil-associated protein kinase (ROCK) signaling pathway, restrain axon development and polarization. Surprisingly, the genetic control of neuronal polarity has remained largely unexplored. Here, we report that, in primary cultured neurons, expression of the histone methyltransferase G9a and nuclear translocation of its major splicing isoform (G9a/E10+) peak at the time of axon formation. RNAi suppression of G9a/E10+ or pharmacological blockade of G9a constrains neuronal migration, axon initiation, and the establishment of neuronal polarity in situ and in vitro. Inhibition of G9a function upregulates RhoA-ROCK activity by increasing the expression of Lfc, a guanine nucleotide exchange factor (GEF) for RhoA. Together, these results identify G9a as a player in neuronal polarization.

Gonadal hormone-independent sex differences in GABAA receptor activation in rat embryonic hypothalamic neurons.

BACKGROUND AND PURPOSE: GABAA receptor functions are dependent on subunit composition, and, through their activation, GABA can exert trophic actions in immature neurons. Although several sex differences in GABA-mediated responses are known to be dependent on gonadal hormones, few studies have dealt with sex differences detected before the critical period of brain masculinisation. In this study, we assessed GABAA receptor functionality in sexually segregated neurons before brain hormonal masculinisation. EXPERIMENTAL APPROACH: Ventromedial hypothalamic neurons were obtained from embryonic day 16 rat brains and grown in vitro for 2 days. Calcium imaging and electrophysiology recordings were carried out to assess GABAA receptor functional parameters. KEY RESULTS: GABAA receptor activation elicited calcium entry in immature hypothalamic neurons mainly through L-type voltage-dependent calcium channels. Nifedipine blocked calcium entry more efficiently in male than in female neurons. There were more male than female neurons responding to GABA, and they needed more time to return to resting levels. Pharmacological characterisation revealed that propofol enhanced GABAA -mediated currents and blunted GABA-mediated calcium entry more efficiently in female neurons than in males. Testosterone treatment did not erase such sex differences. These data suggest sex differences in the expression of GABAA receptor subtypes. CONCLUSION AND IMPLICATIONS: GABA-mediated responses are sexually dimorphic even in the absence of gonadal hormone influence, suggesting genetically biased differences. These results highlight the importance of GABAA receptors in hypothalamic neurons even before hormonal masculinisation of the brain.

INTER/INTRA-OBSERVER EVALUATION BETWEEN RADIOGRAPHS AND TOMOGRAPHIES FOR PROXIMAL HUMERUS FRACTURE.

OBJECTIVE: The use of images in 3D reconstruction is an instrument that facilitates the interpretation of the fracture, observations of deviations, rotations and articular surface. OBJECTIVE: To evaluate the inter-observer and intra-observer reliability of the Neer x AO proximal humerus fracture classification on radiographs versus computed tomography with three-dimensional reconstruction (3D). METHODS: We evaluated the digital radiographs (anteroposterior and profile) and computerized tomography with 3D reconstruction of patients presenting with a proximal humerus fracture, surgically treated at an Orthopedics and Traumatology Service. All radiographs and computed tomography were classified (Neer and AO) by eight (8) orthopedic surgeons, specialists in the upper limb and sent, following the pre-established numeration by the author, in a spreadsheet to the author of the study. RESULTS: The Neer and AO scores were more reproducible when determined by computed tomography with 3D reconstruction, mainly in fractures of greater complexity (Neer 4 parts and AO group C). However, in absolute values, inter and intra-observer reproducibility and concordance still remain low. CONCLUSION: Computed tomography with 3D reconstruction allows a better analysis of fractures of group C and Neer 4 parts. However, the inter and intra-observer agreement does not increase significantly in comparison to the radiographs. Level of evidence III, Study of non-consecutive patients, without gold standard, applied uniformly.

OBJETIVO: O uso de imagens em reconstrução 3D são um instrumento facilitador na interpretação da fratura, observações dos desvios, rotações e superfície articular. OBJETIVO: Avaliar a confiabilidade inter-observador e intra-observador da classificação da fratura de úmero proximal, descrita por Neer x AO, em radiografias versus tomografias computadorizadas com reconstrução tridimensional (3D). MÉTODOS: Avaliamos as radiografias digitais (anteroposterior e perfil) e tomografias computadorizadas com reconstrução 3D de pacientes que apresentavam fratura de úmero proximal, tratados cirurgicamente em um Serviço de Ortopedia e Traumatologia. Todas as radiografias e tomografias computadorizadas foram classificadas (Neer e AO) por oito (8) cirurgiões ortopédicos especialistas em membro superior e enviadas, seguindo a numeração pré-estabelecida pelo autor, em uma planilha para o autor do trabalho. RESULTADOS: A classificação de Neer e AO foram mais reprodutíveis quando determinadas pela tomografia computadorizada com reconstrução 3D, principalmente em fraturas de maior complexidade (Neer 4 partes e AO grupo C). Porém, em valores absolutos, a reprodutibilidade e concordância inter e intraobservador ainda permanecem baixas. CONCLUSÃO: A tomografia com reconstrução 3D, permite uma melhor análise das fraturas do grupo C e Neer 4 partes. Entretanto, não aumenta significativamente a concordância global inter e intraobservador em comparação as radiografias. Nível de Evidência III, Estudo de pacientes não consecutivos, sem padrão ouro, aplicados uniformemente.

Inter/intra-observer evaluation between radiographs and tomographies for proximal humerus fracture / Avaliação inter e intra-observador entre radiografias e tomografias para fratura de úmero proximal

ABSTRACT Objective: The use of images in 3D reconstruction is an instrument that facilitates the interpretation of the fracture, observations of deviations, rotations and articular surface. Objective: To evaluate the inter-observer and intra-observer reliability of the Neer x AO proximal humerus fracture classification on radiographs versus computed tomography with three-dimensional reconstruction (3D). Methods: We evaluated the digital radiographs (anteroposterior and profile) and computerized tomography with 3D reconstruction of patients presenting with a proximal humerus fracture, surgically treated at an Orthopedics and Traumatology Service. All radiographs and computed tomography were classified (Neer and AO) by eight (8) orthopedic surgeons, specialists in the upper limb and sent, following the pre-established numeration by the author, in a spreadsheet to the author of the study. Results: The Neer and AO scores were more reproducible when determined by computed tomography with 3D reconstruction, mainly in fractures of greater complexity (Neer 4 parts and AO group C). However, in absolute values, inter and intra-observer reproducibility and concordance still remain low. Conclusion: Computed tomography with 3D reconstruction allows a better analysis of fractures of group C and Neer 4 parts. However, the inter and intra-observer agreement does not increase significantly in comparison to the radiographs. Level of evidence III, Study of non-consecutive patients, without gold standard, applied uniformly.

RESUMO Objetivo: O uso de imagens em reconstrução 3D são um instrumento facilitador na interpretação da fratura, observações dos desvios, rotações e superfície articular. Objetivo: Avaliar a confiabilidade inter-observador e intra-observador da classificação da fratura de úmero proximal, descrita por Neer x AO, em radiografias versus tomografias computadorizadas com reconstrução tridimensional (3D). Métodos: Avaliamos as radiografias digitais (anteroposterior e perfil) e tomografias computadorizadas com reconstrução 3D de pacientes que apresentavam fratura de úmero proximal, tratados cirurgicamente em um Serviço de Ortopedia e Traumatologia. Todas as radiografias e tomografias computadorizadas foram classificadas (Neer e AO) por oito (8) cirurgiões ortopédicos especialistas em membro superior e enviadas, seguindo a numeração pré-estabelecida pelo autor, em uma planilha para o autor do trabalho. Resultados: A classificação de Neer e AO foram mais reprodutíveis quando determinadas pela tomografia computadorizada com reconstrução 3D, principalmente em fraturas de maior complexidade (Neer 4 partes e AO grupo C). Porém, em valores absolutos, a reprodutibilidade e concordância inter e intraobservador ainda permanecem baixas. Conclusão: A tomografia com reconstrução 3D, permite uma melhor análise das fraturas do grupo C e Neer 4 partes. Entretanto, não aumenta significativamente a concordância global inter e intraobservador em comparação as radiografias. Nível de Evidência III, Estudo de pacientes não consecutivos, sem padrão ouro, aplicados uniformemente.

MEASURING THE DISTANCE BETWEEN STERNOCLAVICULAR JOINT AND HILAR STRUCTURES WITH TOMOGRAPHY.

OBJECTIVES: To evaluate the tomographic distance between the sternoclavicular joints and the nearest hilar structures. METHODS: Computed tomography images (axial and sagittal slices) in 120 healthy individuals (60 men and 60 women) between 18 and 60 years old were prospectively analyzed. The distances from both sternoclavicular joints to the respective brachiocephalic veins, trachea, esophagus, and lung apexes were measured and related to age, sex, and body mass index. RESULTS: Statistically significant differences were found in the distance from the right and left sternoclavicular joint distances and the corresponding brachiocephalic vein, esophagus, and lung apexes. In women, both sides were closer to the noble structures. In patients with body mass index <25, the distances were significantly less than in heavier patients. CONCLUSION: The left sternoclavicular joint is closer to the hilar structures than the contralateral side. In women, both sternoclavicular joints are closer to the brachiocephalic veins, esophagus, and lung apexes than in men. Patients with body mass index <25 have shorter distances between these joints and the brachiocephalic veins and esophagus. Level of Evidence II; Prognostic studies - Investigating the effect of a patient characteristic on the outcome of disease.

OBJETIVOS: avaliar a distância tomográfica entre as articulações esternoclaviculares até as estruturas hilares mais próximas. MÉTODOS: foram analisados prospectivamente cortes tomográficos axiais e sagitais em 120 indivíduos hígidos (60 homens e 60 mulheres), entre 18 e 60 anos, sendo mensuradas as distâncias de ambas as articulações esternoclaviculares até as respectivas veias braquiocefálicas, traqueia, esôfago e ápices pulmonares, relacionando-as com idade, gênero e índice de massa corporal. RESULTADOS: houve diferença estatisticamente significativa entre as distâncias da articulação esternoclavicular direita e esquerda até a veia braquiocefálica correspondente, esôfago e ápices pulmonares. Nas mulheres, ambos os lados estavam mais próximos das estruturas nobres. Pacientes com índice de massa corporal <25 as distâncias foram significativamente menores quando comparados a índices superiores. CONCLUSÃO: articulação esternoclavicular esquerda está mais próxima às estruturas hilares do que o lado direito. Nas mulheres, as articulações esternoclaviculares bilaterias encontram-se mais próximas das veias braquiocefálicas, esôfago e ápices pulmonares, comparadas aos homens. Pacientes com índice de massa corporal <25 apresentam distâncias menores da articulação até as veias braquiocefálicas e esôfago. Nível de Evidência II. Estudos prognósticos ­ Investigação do efeito de característica de um paciente sobre o desfecho da doença.

Measuring the distance between sternoclavicular joint and hilar structures with tomography / Medida da distância da articulação esternoclavicular as estruturas hilares por tomografia

ABSTRACT Objectives To evaluate the tomographic distance between the sternoclavicular joints and the nearest hilar structures. Methods Computed tomography images (axial and sagittal slices) in 120 healthy individuals (60 men and 60 women) between 18 and 60 years old were prospectively analyzed. The distances from both sternoclavicular joints to the respective brachiocephalic veins, trachea, esophagus, and lung apexes were measured and related to age, sex, and body mass index. Results Statistically significant differences were found in the distance from the right and left sternoclavicular joint distances and the corresponding brachiocephalic vein, esophagus, and lung apexes. In women, both sides were closer to the noble structures. In patients with body mass index <25, the distances were significantly less than in heavier patients. Conclusion The left sternoclavicular joint is closer to the hilar structures than the contralateral side. In women, both sternoclavicular joints are closer to the brachiocephalic veins, esophagus, and lung apexes than in men. Patients with body mass index <25 have shorter distances between these joints and the brachiocephalic veins and esophagus. Level of Evidence II; Prognostic studies - Investigating the effect of a patient characteristic on the outcome of disease.

RESUMO Objetivos avaliar a distância tomográfica entre as articulações esternoclaviculares até as estruturas hilares mais próximas. Métodos foram analisados prospectivamente cortes tomográficos axiais e sagitais em 120 indivíduos hígidos (60 homens e 60 mulheres), entre 18 e 60 anos, sendo mensuradas as distâncias de ambas as articulações esternoclaviculares até as respectivas veias braquiocefálicas, traqueia, esôfago e ápices pulmonares, relacionando-as com idade, gênero e índice de massa corporal. Resultados houve diferença estatisticamente significativa entre as distâncias da articulação esternoclavicular direita e esquerda até a veia braquiocefálica correspondente, esôfago e ápices pulmonares. Nas mulheres, ambos os lados estavam mais próximos das estruturas nobres. Pacientes com índice de massa corporal <25 as distâncias foram significativamente menores quando comparados a índices superiores. Conclusão articulação esternoclavicular esquerda está mais próxima às estruturas hilares do que o lado direito. Nas mulheres, as articulações esternoclaviculares bilaterias encontram-se mais próximas das veias braquiocefálicas, esôfago e ápices pulmonares, comparadas aos homens. Pacientes com índice de massa corporal <25 apresentam distâncias menores da articulação até as veias braquiocefálicas e esôfago. Nível de Evidência II. Estudos prognósticos - Investigação do efeito de característica de um paciente sobre o desfecho da doença.

From birth to death: A role for reactive oxygen species in neuronal development.

Historically, ROS have been considered toxic molecules, especially when their intracellular concentration reaches high values. However, physiological levels of ROS support crucial cellular processes, acting as second messengers able to regulate intrinsic signaling pathways. Specifically, both the central and peripheral nervous systems are especially susceptible to changes in the redox state, developing either a defense or adaptive response depending on the concentration, source and duration of the pro-oxidative stimuli. In this review, we summarize classical and modern concepts regarding ROS physiology, with an emphasis on the role of the NADPH oxidase (NOX) complex, the main enzymatic and regulated source of ROS in the nervous system. We discuss how ROS and redox state contribute to neurogenesis, polarization and maturation of neurons, providing a context for the spatio-temporal conditions in which ROS modulate neural fate, discriminating between "oxidative distress", and "oxidative eustress". Finally, we present a brief discussion about the "physiological range of ROS concentration", and suggest that these values depend on several parameters, including cell type, developmental stage, and the source and type of pro-oxidative molecule.

Intrathoracic fracture-dislocation of the humerus - case report and literature review.

Shoulder fracture-dislocations are uncommon. Those associated with intrathoracic dislocation are very rare conditions, resulting from high-energy trauma; usually, the affected limb is in an abduction position. In Brazil, there is only one report of a teenager with displacement of the epiphysis into the chest cavity; the present is the first adult patient report of intrathoracic dislocation of the humerus. The authors present the case of a patient female, aged 56 years, who was hit by motorcycle and thrown approximately 5 meters away. She was rescued on site with thoracic, pelvic, and right upper limb trauma. Her chest was drained due to pneumothorax and multiple fractures of ribs; she was diagnosed with fracture-dislocation in four parts, with intrathoracic dislocation of the humeral head. Displaced forearm bones fracture was also diagnosed; the olecranon, scaphoid, and ischiopubic fractures were not displaced. The patient underwent a joint procedure with a cardiothoracic surgery team to remove the humeral head through thoracotomy and chest drainage; subsequently, a partial arthroplasty of the humerus was performed, with graft from the humeral head and fixation of forearm fractures. Conservative treatment was chosen for the other fractures. After three months, all fractures were healed with gradual functional improvement. The patient remained in physiotherapy and orthopedic monitoring, having been discharged from the thoracic surgery; in a severe depressive episode, the patient committed suicide after 11 months of the trauma.

As fraturas luxações do ombro são incomuns; aquelas associadas com deslocamento intratorácico são condições muito raras e decorrentes de traumas de alta energia, nos quais o membro acometido geralmente está numa posição de abdução. No Brasil, existe apenas o relato de um adolescente com deslocamento da epífise para o interior da caixa torácica. Esse é o primeiro relato de paciente adulto com luxação intratoracica de umero.Os autores apresentam um caso de paciente feminina de 56 anos, atropelada por motocicleta e arremessada em torno de cinco metros de distância. Foi socorrida no local com trauma torácico, pélvico e do membro superior direito. Teve o tórax drenado devido a pneumotórax e múltiplas fraturas de arcos costais e recebeu o diagnóstico de fratura luxação em quatro partes com deslocamento intratorácico da cabeça umeral. Foram diagnosticadas fratura de ossos do antebraço desviada e fraturas do olécrano, do escafoide e dos ramos isquiopúbicos sem desvios. A paciente foi submetida a procedimento cirúrgico conjunto com uma equipe de cirurgia cardiotorácica para retirada da cabeça umeral por meio de toracotomia e drenagem torácica; posteriormente, uma artroplastia parcial do úmero foi feita, com enxertia proveniente da cabeça umeral, além de fixação das fraturas do antebraço. Nas demais fraturas, optou-se por tratamento conservador. Após três meses, todas as fraturas apresentavam-se consolidadas com melhoria gradual das funções. A paciente permaneceu em acompanhamento fisioterápico e ortopédico e recebeu alta da cirurgia torácica. Dentro de um quadro depressivo grave, cometeu suicídio 11 meses após o trauma.

Intrathoracic fracture-dislocation of the humerus - case report and literature review / Fratura luxação intratorácica do úmero - Relato de caso e revisão da literatura

ABSTRACT Shoulder fracture-dislocations are uncommon. Those associated with intrathoracic dislocation are very rare conditions, resulting from high-energy trauma; usually, the affected limb is in an abduction position. In Brazil, there is only one report of a teenager with displacement of the epiphysis into the chest cavity; the present is the first adult patient report of intrathoracic dislocation of the humerus. The authors present the case of a patient female, aged 56 years, who was hit by motorcycle and thrown approximately 5 meters away. She was rescued on site with thoracic, pelvic, and right upper limb trauma. Her chest was drained due to pneumothorax and multiple fractures of ribs; she was diagnosed with fracture-dislocation in four parts, with intrathoracic dislocation of the humeral head. Displaced forearm bones fracture was also diagnosed; the olecranon, scaphoid, and ischiopubic fractures were not displaced. The patient underwent a joint procedure with a cardiothoracic surgery team to remove the humeral head through thoracotomy and chest drainage; subsequently, a partial arthroplasty of the humerus was performed, with graft from the humeral head and fixation of forearm fractures. Conservative treatment was chosen for the other fractures. After three months, all fractures were healed with gradual functional improvement. The patient remained in physiotherapy and orthopedic monitoring, having been discharged from the thoracic surgery; in a severe depressive episode, the patient committed suicide after 11 months of the trauma.

RESUMO As fraturas luxações do ombro são incomuns; aquelas associadas com deslocamento intratorácico são condições muito raras e decorrentes de traumas de alta energia, nos quais o membro acometido geralmente está numa posição de abdução. No Brasil, existe apenas o relato de um adolescente com deslocamento da epífise para o interior da caixa torácica. Esse é o primeiro relato de paciente adulto com luxação intratoracica de umero. Os autores apresentam um caso de paciente feminina de 56 anos, atropelada por motocicleta e arremessada em torno de cinco metros de distância. Foi socorrida no local com trauma torácico, pélvico e do membro superior direito. Teve o tórax drenado devido a pneumotórax e múltiplas fraturas de arcos costais e recebeu o diagnóstico de fratura luxação em quatro partes com deslocamento intratorácico da cabeça umeral. Foram diagnosticadas fratura de ossos do antebraço desviada e fraturas do olécrano, do escafoide e dos ramos isquiopúbicos sem desvios. A paciente foi submetida a procedimento cirúrgico conjunto com uma equipe de cirurgia cardiotorácica para retirada da cabeça umeral por meio de toracotomia e drenagem torácica; posteriormente, uma artroplastia parcial do úmero foi feita, com enxertia proveniente da cabeça umeral, além de fixação das fraturas do antebraço. Nas demais fraturas, optou-se por tratamento conservador. Após três meses, todas as fraturas apresentavam-se consolidadas com melhoria gradual das funções. A paciente permaneceu em acompanhamento fisioterápico e ortopédico e recebeu alta da cirurgia torácica. Dentro de um quadro depressivo grave, cometeu suicídio 11 meses após o trauma.

A Feed-Forward Mechanism Involving the NOX Complex and RyR-Mediated Ca2+ Release During Axonal Specification.

Physiological levels of ROS support neurite outgrowth and axonal specification, but the mechanisms by which ROS are able to shape neurons remain unknown. Ca2+, a broad intracellular second messenger, promotes both Rac1 activation and neurite extension. Ca2+ release from the endoplasmic reticulum, mediated by both the IP3R1 and ryanodine receptor (RyR) channels, requires physiological ROS levels that are mainly sustained by the NADPH oxidase (NOX) complex. In this work, we explore the contribution of the link between NOX and RyR-mediated Ca2+ release toward axonal specification of rat hippocampal neurons. Using genetic approaches, we find that NOX activation promotes both axonal development and Rac1 activation through a RyR-mediated mechanism, which in turn activates NOX through Rac1, one of the NOX subunits. Collectively, these data suggest a feedforward mechanism that integrates both NOX activity and RyR-mediated Ca2+ release to support cellular mechanisms involved in axon development. SIGNIFICANCE STATEMENT: High levels of ROS are frequently associated with oxidative stress and disease. In contrast, physiological levels of ROS, mainly sustained by the NADPH oxidase (NOX) complex, promote neuronal development and axonal growth. However, the mechanisms by which ROS shape neurons have not been described. Our work suggests that NOX-derived ROS promote axonal growth by regulating Rac1 activity, a molecular determinant of axonal growth, through a ryanodine receptor (RyR)-mediated Ca2+ release mechanism. In addition, Rac1, one of the NOX subunits, was activated after RyR-mediated Ca2+ release, suggesting a feedforward mechanism between NOX and RyR. Collectively, our data suggest a novel mechanism that is instrumental in sustaining physiological levels of ROS required for axonal growth of hippocampal neurons.

Actin filaments-A target for redox regulation.

Actin and its ability to polymerize into dynamic filaments is critical for the form and function of cells throughout the body. While multiple proteins have been characterized as affecting actin dynamics through noncovalent means, actin and its protein regulators are also susceptible to covalent modifications of their amino acid residues. In this regard, oxidation-reduction (Redox) intermediates have emerged as key modulators of the actin cytoskeleton with multiple different effects on cellular form and function. Here, we review work implicating Redox intermediates in post-translationally altering actin and discuss what is known regarding how these alterations affect the properties of actin. We also focus on two of the best characterized enzymatic sources of these Redox intermediates-the NADPH oxidase NOX and the flavoprotein monooxygenase MICAL-and detail how they have both been identified as altering actin, but share little similarity and employ different means to regulate actin dynamics. Finally, we discuss the role of these enzymes and redox signaling in regulating the actin cytoskeleton in vivo and highlight their importance for neuronal form and function in health and disease. © 2016 Wiley Periodicals, Inc.

Ligand-mediated Galectin-1 endocytosis prevents intraneural H2O2 production promoting F-actin dynamics reactivation and axonal re-growth.

UNLABELLED: Axonal growth cone collapse following spinal cord injury (SCI) is promoted by semaphorin3A (Sema3A) signaling via PlexinA4 surface receptor. This interaction triggers intracellular signaling events leading to increased hydrogen peroxide levels which in turn promote filamentous actin (F-actin) destabilization and subsequent inhibition of axonal re-growth. In the current study, we demonstrated that treatment with galectin-1 (Gal-1), in its dimeric form, promotes a decrease in hydrogen peroxide (H2O2) levels and F-actin repolimerization in the growth cone and in the filopodium of neuron surfaces. This effect was dependent on the carbohydrate recognition activity of Gal-1, as it was prevented using a Gal-1 mutant lacking carbohydrate-binding activity. Furthermore, Gal-1 promoted its own active ligand-mediated endocytosis together with the PlexinA4 receptor, through mechanisms involving complex branched N-glycans. In summary, our results suggest that Gal-1, mainly in its dimeric form, promotes re-activation of actin cytoskeleton dynamics via internalization of the PlexinA4/Gal-1 complex. This mechanism could explain, at least in part, critical events in axonal regeneration including the full axonal re-growth process, de novo formation of synapse clustering, axonal re-myelination and functional recovery of coordinated locomotor activities in an in vivo acute and chronic SCI model. SIGNIFICANCE STATEMENT: Axonal regeneration is a response of injured nerve cells critical for nerve repair in human spinal cord injury. Understanding the molecular mechanisms controlling nerve repair by Galectin-1, may be critical for therapeutic intervention. Our results show that Galectin-1; in its dimeric form, interferes with hydrogen peroxide production triggered by Semaphorin3A. The high levels of this reactive oxygen species (ROS) seem to be the main factor preventing axonal regeneration due to promotion of actin depolymerization at the axonal growth cone. Thus, Galectin-1 administration emerges as a novel therapeutic modality for promoting nerve repair and preventing axonal loss.

Dissecting the role of redox signaling in neuronal development.

The generation of abnormally high levels of reactive oxygen species (ROS) is linked to cellular dysfunction, including neuronal toxicity and neurodegeneration. However, physiological ROS production modulates redox-sensitive roles of several molecules such as transcription factors, signaling proteins, and cytoskeletal components. Changes in the functions of redox-sensitive proteins may be important for defining key aspects of stem cell proliferation and differentiation, neuronal maturation, and neuronal plasticity. In neurons, most of the studies have been focused on the pathological implications of such modifications and only very recently their essential roles in neuronal development and plasticity has been recognized. In this review, we discuss the participation of NADPH oxidases (NOXs) and a family of protein-methionine sulfoxide oxidases, named molecule interacting with CasLs, as regulated enzymatic sources of ROS production in neurons, and describes the contribution of ROS signaling to neurogenesis and differentiation, neurite outgrowth, and neuronal plasticity. We review the role of reactive oxygen species (ROS) in neurogenesis, axon growth, and guidance and NMDA-receptor-mediated plasticity, LTP, and memory. ROS participation is presented in the context of NADPH oxidase and MICAL functions and their importance for brain functions.