Effect of intravenous anesthetic propofol on synaptic vesicle exocytosis at the frog neuromuscular junction

Aim: To investigate the presynaptic effects of propofol, a short-acting intravenous anesthetic, in the frog neuromuscular junction. Methods: Frog cutaneous pectoris nerve muscle preparations were prepared. A fluorescent tool (FM1-43) was used to visualize the effect of propofol on synaptic vesicle exocytosos in the frog neuromuscular junction. Results: Low concentrations of propofol, ranging from 10 to 25 μmol/L, enhanced spontaneous vesicle exocytosis monitored by FM1-43 in a Ca2+-dependent and Na+-independent fashion. Higher concentrations of propofol (50, 100, and 200 μmol/L) had no effect on spontaneous exocytosis. By contrast, higher concentrations of propofol inhibited the Na+-dependent exocytosis evoked by 4-aminopyridine but did not affect the Na+-independent exocytosis evoked by KCl. This action was similar and non-additive with that observed by tetrodotoxin, a Na+ channel blocker. Conclusion: Our data suggest that propofol has a dose-dependent presynaptic effect at the neuromuscular transmission which may help to understand some of the clinical effects of this agent on neuromuscular function

Illuminating the Brain With X-Rays: Contributions and Future Perspectives of High-Resolution Microtomography to Neuroscience

The assessment of three-dimensional (3D) brain cytoarchitecture at a cellular resolution remains a great challenge in the field of neuroscience and constant development of imaging techniques has become crucial, particularly when it comes to offering direct and clear obtention of data from macro to nano scales. Magnetic resonance imaging (MRI) and electron or optical microscopy, although valuable, still face some issues such as the lack of contrast and extensive sample preparation protocols. In this context, x-ray microtomography (μCT) has become a promising non-destructive tool for imaging a broad range of samples, from dense materials to soft biological specimens. It is a new supplemental method to be explored for deciphering the cytoarchitecture and connectivity of the brain. This review aims to bring together published works using x-ray μCT in neurobiology in order to discuss the achievements made so far and the future of this technique for neuroscience

Reverse engineering the neuroblastoma regulatory network uncovers MAX as one of the master regulators of tumor progression

Neuroblastoma is the most common extracranial tumor and a major cause of infant cancer mortality worldwide. Despite its importance, little is known about its molecular mechanisms. A striking feature of this tumor is its clinical heterogeneity. Possible outcomes range from aggressive invasion to other tissues, causing patient death, to spontaneous disease regression or differentiation into benign ganglioneuromas. Several efforts have been made in order to find tumor progression markers. In this work, we have reconstructed the neuroblastoma regulatory network using an information-theoretic approach in order to find genes involved in tumor progression and that could be used as outcome predictors or as therapeutic targets. We have queried the reconstructed neuroblastoma regulatory network using an aggressive neuroblastoma metastasis gene signature in order to find its master regulators (MRs). MRs expression profiles were then investigated in other neuroblastoma datasets so as to detect possible clinical significance. Our analysis pointed MAX as one of the MRs of neuroblastoma progression. We have found that higher MAX expression correlated with favorable patient outcomes. We have also found that MAX expression and protein levels were increased during neuroblastoma SH-SY5Y cells differentiation. We propose that MAX is involved in neuroblastoma progression, possibly increasing cell differentiation by means of regulating the availability of MYC:MAX heterodimers. This mechanism is consistent with the results found in our SH-SY5Y differentiation protocol, suggesting that MAX has a more central role in these cells differentiation than previously reported. Overexpression of MAX has been identified as anti-tumorigenic in other works, but, to our knowledge, this is the first time that the link between the expression of this gene and malignancy was verified under physiological conditions

Avaliação in silico de derivados naftoquinônicos frente à NSP9 do SARS-COV-2 / In silico evaluation of naphtoquinonic derivatives against SARS-COV-2 NSP9

O SARS-CoV-2 é o agente etiológico da COVID-19, que representa uma emergência de saúde global. A proteína Nsp9 Replicase é crítica para a maquinaria de RNA replicase e parece desempenhar um papel fundamental na transcrição do genoma do RNA do SARS-CoV-2. Dessa forma, essa proteína não estrutural pode ser um alvo potencial para a pesquisa de fármacos capazes de inibir a progressão viral. Em vista das poucas opções terapêuticas disponíveis para essa doença, buscou-se planejar, por meio de triagem virtual, derivados naftoquinônicos com potencial de inibição da Nsp9 Replicase e que apresentassem perfil físico-químicos ideais para candidatos a fármacos. Foram planejados 6 derivados, onde apenas 2 (D5 e D6) obtiveram um perfil de complementariedade com a enzima Nsp9. Quanto ao perfil físico-químico, D5 atendem à Regrado dos 5 Lipinski. Adicionalmente, as etapas para a sua síntese são simples e de custo acessível, tornando viável sua produção para testes in vitro e in vivo. Sendo assim, estre trabalho traz uma proposta de nova molécula de fácil obtenção e características farmacocinéticas apropriadas e que apresenta potencial de inibição de uma importante proteína de SARS-CoV-2, responsável por um dos maiores problemas de saúde pública da era moderna

High-resolution synchrotron-based X-ray microtomography as a tool to unveil the three-dimensional neuronal architecture of the brain

The assessment of neuronal number, spatial organization and connectivity is fundamental for a complete understanding of brain function. However, the evaluation of the three-dimensional (3D) brain cytoarchitecture at cellular resolution persists as a great challenge in the field of neuroscience. In this context, X-ray microtomography has shown to be a valuable non-destructive tool for imaging a broad range of samples, from dense materials to soft biological specimens, arisen as a new method for deciphering the cytoarchitecture and connectivity of the brain. In this work we present a method for imaging whole neurons in the brain, combining synchrotron-based X-ray microtomography with the Golgi-Cox mercury-based impregnation protocol. In contrast to optical 3D techniques, the approach shown here does neither require tissue slicing or clearing, and allows the investigation of several cells within a 3D region of the brain

Angiotensin Converting Enzyme Regulates Cell Proliferation and Migration

Background The angiotensin-I converting enzyme (ACE) plays a central role in the renin-angiotensin system, acting by converting the hormone angiotensin-I to the active peptide angiotensin-II (Ang-II). More recently, ACE was shown to act as a receptor for Ang-II, and its expression level was demonstrated to be higher in melanoma cells compared to their normal counterparts. However, the function that ACE plays as an Ang-II receptor in melanoma cells has not been defined yet. Aim Therefore, our aim was to examine the role of ACE in tumor cell proliferation and migration. Results We found that upon binding to ACE, Ang-II internalizes with a faster onset compared to the binding of Ang-II to its classical AT1 receptor. We also found that the complex Ang-II/ACE translocates to the nucleus, through a clathrin-mediated process, triggering a transient nuclear Ca2+ signal. In silico studies revealed a possible interaction site between ACE and phospholipase C (PLC), and experimental results in CHO cells, demonstrated that the beta 3 isoform of PLC is the one involved in the Ca2+ signals induced by Ang-II/ACE interaction. Further studies in melanoma cells (TM-5) showed that Ang-II induced cell proliferation through ACE activation, an event that could be inhibited either by ACE inhibitor (Lisinopril) or by the silencing of ACE. In addition, we found that stimulation of ACE by Ang-II caused the melanoma cells to migrate, at least in part due to decreased vinculin expression, a focal adhesion structural protein. Conclusion ACE activation regulates melanoma cell proliferation and migration.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)INCT Nanocarbono - UFMG (Brazil)Univ Fed Minas Gerais, Dept Physiol & Biophys, Belo Horizonte, MG, BrazilUniv Fed Sao Joao del Rei, Dept Nat Sci, Sao Joao Del Rei, MG, BrazilUniv Fed Ceara, Dept Phys, Fortaleza, CE, BrazilUniv Fed Sao Paulo, Dept Biophys, Sao Paulo, SP, BrazilUniv Fed Minas Gerais, Dept Phys, Belo Horizonte, MG, BrazilUniv Fed Minas Gerais, Dept Morphol, Belo Horizonte, MG, BrazilDepartment of Biophysics, Universidade Federal de São Paulo (UNIFESP), São Paulo, SP, BrazilWeb of Scienc

Design, Synthesis and Biological Evaluation of Novel Triazole N-acylhydrazone Hybrids for Alzheimer's Disease

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder that involves different pathogenic mechanisms. In this regard, the goal of this study was the design and synthesis of new compounds with multifunctional pharmacological activity by molecular hybridization of structural fragments of curcumin and resveratrol connected by an N-acyl-hydrazone function linked to a 1,4-disubstituted triazole system. Among these hybrid compounds, derivative 3e showed the ability to inhibit acetylcholinesterase activity, the intracellular formation of reactive oxygen species as well as the neurotoxicity elicited by Aβ42 oligomers in neuronal SH-SY5Y cells. In parallel, compound 3e showed a good profile of safety and ADME parameters. Taken together, these results suggest that 3e could be considered a lead compound for the further development of AD therapeutics

Análise dos Critérios Imunofenotípicos por Citometria de Fluxo para Definição das Doenças Linfoproliferativas Crônicas de Células B

Introdução: A citometria de fluxo é uma metodologia importante para o diagnóstico das doenças linfoproliferativas crônicas de células B (DLPCB), contudo, por vezes, o citometrista não encontra subsídios suficientes para a definição exata da entidade patológica envolvida. Objetivo: Analisar os laudos emitidos a pacientes com doenças linfoproliferativas crônicas (DLPC) atendidos em um laboratório particular de Belém-PA, segundo os critérios de classificação estabelecidos pelos estudos de Matutes et al. e Craig e Foon. Método: Estudo retrospectivo com laudos de pacientes que realizaram imunofenotipagem por citometria de fluxo para diagnóstico de DLPCB no período entre setembro de 2015 a dezembro de 2019. Resultados: Depois de aplicados os critérios de Matutes et al. e Craig e Foon para os laudos analisados, observou-se concordância em: 45,24% casos de leucemia linfoide crônica de células B/linfoma linfocítico de pequenas células B; 14,29% casos de linfoma folicular; 4,76% casos de leucemia de células pilosas; e 21,43% de casos definidos como “outras DLPCB não classificáveis por citometria de fluxo”. Entretanto, o teste de hipóteses de Hotelling (p=0,0409) mostrou haver diferença estatística para a definição das DLPCB segundo os critérios aplicados. Conclusão: Os resultados ressaltam que, mesmo sendo a citometria de fluxo importante para a caracterização das DLPCB, por vezes, o citometrista necessita incluir no laudo a categoria “outras doenças linfoproliferativas crônicas de células B não classificadas por citometria de fluxo” para induzir o prescritor a solicitar mais exames complementares

Design, synthesis, and biological evaluation of new thalidomide–donepezil hybrids as neuroprotective agents targeting cholinesterases and neuroinflammation

A new series of eight multifunctional thalidomide–donepezil hybrids were synthesized based on the multi target-directed ligand strategy and evaluated as potential neuroprotective, cholinesterase inhibitors and anti neuroinflammatory agents against neurodegenerative diseases. A molecular hybridization approach was used for structural design by combining the N-benzylpiperidine pharmacophore of donepezil and the isoindoline 1,3-dione fragment from the thalidomide structure. The most promising compound, PQM-189 (3g), showed good AChE inhibitory activity with an IC50 value of 3.15 μM, which was predicted by docking studies as interacting with the enzyme in the same orientation observed in the AChE–donepezil complex and a similar profile of interaction. Additionally, compound 3g significantly decreased iNOS and IL-1β levels by 43% and 39%, respectively, after 24 h of incubation with lipopolysaccharide. In vivo data confirmed the ability of 3g to prevent locomotor impairment and changes in feeding behavior elicited by lipopolysaccharide. Moreover, the PAMPA assay evidenced adequate blood–brain barrier and gastrointestinal tract permeabilities with an Fa value of 69.8%. Altogether, these biological data suggest that compound 3g can treat the inflammatory process and oxidative stress resulting from the overexpression of iNOS and therefore the increase in reactive nitrogen species, and regulate the release of pro-inflammatory cytokines such as IL-1β. In this regard, compound PQM-189 (3g) was revealed to be a promising neuroprotective and anti-neuroinflammatory agent with an innovative thalidomide–donepezil-based hybrid molecular architectur

Emerging Role of HMGB1 in the Pathogenesis of Schistosomiasis Liver Fibrosis

In chronic schistosomiasis, liver fibrosis is linked to portal hypertension, which is a condition associated with high mortality and morbidity. High mobility group box 1 (HMGB1) was originally described as a nuclear protein that functions as a structural co-factor in transcriptional regulation. However, HMGB1 can also be secreted into the extracellular milieu under appropriate signal stimulation. Extracellular HMGB1 acts as a multifunctional cytokine that contributes to infection, injury, inflammation, and immune responses by binding to specific cell-surface receptors. HMGB1 is involved in fibrotic diseases. From a clinical perspective, HMGB1 inhibition may represent a promising therapeutic approach for treating tissue fibrosis. In this study, we demonstrate elevated levels of HMGB1 in the sera in experimental mice or in patients with schistosomiasis. Using immunohistochemistry, we demonstrated that HMGB1 trafficking in the hepatocytes of mice suffering from acute schistosomiasis was inhibited by Glycyrrhizin, a well-known HMGB1 direct inhibitor, as well as by DIC, a novel and potential anti-HMGB1 compound. HMGB1 inhibition led to significant downregulation of IL-6, IL4, IL-5, IL-13, IL-17A, which are involved in the exacerbation of the immune response and liver fibrogenesis. Importantly, infected mice that were treated with DIC or GZR to inhibit HMGB1 pro-inflammatory activity showed a significant increase in survival and a reduction of over 50% in the area of liver fibrosis. Taken together, our findings indicate that HMGB1 is a key mediator of schistosomotic granuloma formation and liver fibrosis and may represent an outstanding target for the treatment of schistosomiasis