39 results on '"Neto VM"'
Search Results
2. PI3K Signaling Pathways as a Molecular Target for Glioblastoma Multiforme.
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da Silva ALL, de Araújo TPG, de Albuquerque Ferreira SC, Leite AB, da Silva JKS, Albuquerque LWN, de Lima ARV, Barros HCS, Silva LR, da Silva-Júnior EF, de Araújo-Júnior JX, Neto VM, de Queiroz AC, and Alexandre-Moreira MS
- Subjects
- Humans, Phosphatidylinositol 3-Kinases genetics, Phosphatidylinositol 3-Kinases metabolism, Signal Transduction, Glioblastoma drug therapy, Glioblastoma genetics, Glioblastoma metabolism, Brain Neoplasms drug therapy, Brain Neoplasms genetics, Brain Neoplasms pathology
- Abstract
Glioblastoma multiforme (GBM) is the most common type of cancer that affects the central nervous system (CNS). It currently accounts for about 2% of diagnosed malignant tumors worldwide, with 296,000 new cases reported per year. The first-choice treatment consists of surgical resection, radiotherapy, and adjuvant chemotherapy, which increases patients' survival by 15 months. New clinical and pre-clinical research aims to improve this prognosis by proposing the search for new drugs that effectively eliminate cancer cells, circumventing problems such as resistance to treatment. One of the promising therapeutic strategies in the treatment of GBM is the inhibition of the phosphatidylinositol 3-kinase (PI3K) pathway, which is closely related to the process of tumor carcinogenesis. This review sought to address the main scientific studies of synthetic or natural drug prototypes that target specific therapy co-directed via the PI3K pathway, against human glioblastoma., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)
- Published
- 2024
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3. Clinical evaluation of culturable bacteria, endotoxins and lipoteichoic acid in teeth with vital normal pulp tissues.
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Chiarelli-Neto VM, de Aveiro E, Bronzato JD, Arruda-Vasconcelos R, Louzada LM, Godoi EP Jr, Lopes EM, de-Jesus-Soares A, Ferraz CCR, Almeida JFA, Marciano MA, and Gomes BPFA
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- Humans, Lipopolysaccharides, Dental Pulp Cavity microbiology, Bacteria, Endotoxins, Periapical Periodontitis
- Abstract
The objective of this study was to investigate the presence of culturable bacteria, endotoxins (LPS) and lipoteichoic acid (LTA) levels in teeth with normal vital pulp (NVP) with intact crowns (IC) and those with coronal restoration (CR) limited to the enamel level. A total of 20 teeth indicated for endodontic treatment due to prosthetic reasons were selected. Samples were collected from the root canals. The levels of cultivable bacteria, LPS and LTA were assessed. Statistical analyses were performed at significance level set at 5%. None of the teeth presented microbial growth. In the IC group, the LPS levels were limited to the lowest concentration of LPS. On the contrary, higher LPS and LTA levels were detected in teeth with CR. It was concluded that teeth with NVP and IC were negative for bacteria, LPS and LTA; while teeth with CR were positive for bacterial virulence factors., (© 2023 Australian Society of Endodontology Inc.)
- Published
- 2023
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4. Microbiota present in combined endodontic-periodontal diseases and its risks for endocarditis.
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Gomes BPFA, Berber VB, Chiarelli-Neto VM, Aveiro E, Chapola RC, Passini MRZ, Lopes EM, Chen T, and Paster BJ
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- Humans, Bacteria, Periodontal Pocket microbiology, Periodontal Diseases, Endocarditis, Microbiota
- Abstract
Introduction: Infective endocarditis (IE) is an inflammatory disease usually caused by bacteria that enter the bloodstream and establish infections in the inner linings or valves of the heart, including blood vessels. Despite the availability of modern antimicrobial and surgical treatments, IE continues to cause substantial morbidity and mortality. Oral microbiota is considered one of the most significant risk factors for IE. The objective of this study was to evaluate the microbiota present in root canal (RC) and periodontal pocket (PP) clinical samples in cases with combined endo-periodontal lesions (EPL) to detect species related to IE using NGS., Methods: Microbial samples were collected from 15 RCs and their associated PPs, also from 05 RCs with vital pulp tissues (negative control, NC). Genomic studies associated with bioinformatics, combined with structuring of a database (genetic sequences of bacteria reported for infective endocarditis), allowed for the assessment of the microbial community at both sites. Functional prediction was conducted using PICRUSt2., Results: Parvimonas, Streptococcus, and Enterococcus were the major genera detected in the RCs and PPs. A total of 79, 96, and 11 species were identified in the RCs, PPs, and NCs, respectively. From them, a total of 34 species from RCs, 53 from PPs, and 2 from NCs were related to IE. Functional inference demonstrated that CR and PP microbiological profiles may not be the only risk factors for IE but may also be associated with systemic diseases, including myocarditis, human cytomegalovirus infection, bacterial invasion of epithelial cells, Huntington's disease, amyotrophic lateral sclerosis, and hypertrophic cardiomyopathy. Additionally, it was possible to predict antimicrobial resistance variants for broad-spectrum drugs, including ampicillin, tetracycline, and macrolides., Conclusion: Microorganisms present in the combined EPL may not be the only risk factor for IE but also for systemic diseases. Antimicrobial resistance variants for broad-spectrum drugs were inferred based on PICRUSt-2. State-of-the-art sequencing combined with bioinformatics has proven to be a powerful tool for conducting studies on microbial communities and could considerably assist in the diagnosis of serious infections., Clinical Relevance: Few studies have investigated the microbiota in teeth compromised by combined endo-periodontal lesions (EPL), but none have correlated the microbiological findings to any systemic condition, particularly IE, using NGS techniques. In such cases, the presence of apical periodontitis and periodontal disease can increase IE risk in susceptible patients., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)
- Published
- 2023
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5. Quantitative analysis of culturable bacteria, levels of endotoxins, inflammatory mediators and substance P in teeth with symptomatic irreversible pulpitis and in teeth with vital normal pulp tissues.
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Arruda-Vasconcelos R, Chiarelli-Neto VM, Louzada LM, Aveiro E, Alves-Silva EG, de-Jesus-Soares A, Ferraz CCR, Almeida JFA, Marciano MA, Pecorari VGA, and Gomes BPFA
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- Humans, Substance P, Endotoxins, Lipopolysaccharides, Inflammation Mediators, Tumor Necrosis Factor-alpha, Cross-Sectional Studies, Dental Pulp pathology, Bacteria, Pulpitis
- Abstract
Aim: To comparatively analyse the levels of culturable bacteria, endotoxins (LPS), tumour necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β) and substance P in teeth with symptomatic irreversible pulpitis (SIP) and vital normal pulp (VNP) tissues., Methodology: Thirty-two patients were included (20 teeth with SIP and 12 teeth with VNP tissues) in this cross-sectional study. Samples were collected from the full length of the root canals (microbial analysis) and periapical tissues (2 mm beyond the apex for immunological analysis), using sterile absorbent paper points. The levels of culturable bacteria (culture method), endotoxins (LAL Pyrogent 5000), TNF-α, IL-1β and substance P (ELISA) were assessed. The Mann-Whitney test was used for comparisons between the levels of CFU/mL, LPS, TNF-α, IL-1β and substance P in the SIP and VNP groups. The statistical analysis was performed with the significance level set at 5%., Results: Culturable bacteria were recovered from all teeth with SIP. On the other hand, no positive cultures were observed in the VNP tissues group (p > .05). The levels of LPS were approximately four times higher in teeth with SIP than in teeth with VNP tissues (p < .05). Higher levels of TNF-α and substance P were detected in teeth with SIP (p < .05). On the other hand, no difference in the levels of IL-1β was detected between the two groups (p > .05)., Conclusion: Teeth with symptomatic irreversible pulpitis present higher levels of culturable bacteria, endotoxins, TNF-α and substance P than those with vital normal pulp tissues. On the other hand, the levels of IL-1β were similar in teeth from both groups suggesting reduced implications of this inflammatory mediator in the early stages of infection., (© 2023 British Endodontic Society. Published by John Wiley & Sons Ltd.)
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- 2023
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6. The Use of Liquid Biopsy in the Molecular Analysis of Plasma Compared to the Tumour Tissue from a Patient with Brain Metastasis: A Case Report.
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Aran V, Zogbi VM, Miranda RL, Andreiuolo F, Silva Canedo NH, Nazaré CV, Niemeyer Filho P, and Neto VM
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- Humans, Liquid Biopsy, Mutation, Biopsy, Biomarkers, Tumor, Lung Neoplasms genetics, Lung Neoplasms diagnosis, Brain Neoplasms genetics
- Abstract
Different cancers have multiple genetic mutations, which vary depending on the affected tumour tissue. Small biopsies may not always represent all the genetic landscape of the tumour. To improve the chances of identifying mutations at different disease stages (early, during the disease course, and refractory stage), liquid biopsies offer an advantage to traditional tissue biopsy. In addition, it is possible to detect mutations related to metastatic events depending on the cancer types analysed as will be discussed in this case report, which describes a patient with brain metastasis and lung cancer that harboured K-RAS mutations both in the brain tumour and in the ctDNA present in the bloodstream.
- Published
- 2023
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7. Identification of mutant K-RAS in pituitary macroadenoma.
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Aran V, Heringer M, da Mata PJ, Kasuki L, Miranda RL, Andreiuolo F, Chimelli L, Filho PN, Gadelha MR, and Neto VM
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- Genes, ras, Humans, Mutation genetics, Polymerase Chain Reaction, Adenoma genetics, Pituitary Neoplasms genetics, Proto-Oncogene Proteins p21(ras) genetics
- Abstract
Purpose: RAS genes are among the most frequently mutated genes in cancer, where their mutation frequency varies according to the distinct RAS isoforms and tumour types. Despite occurring more prevalent in malignant tumours, RAS mutations were also observed in few benign tumours. Pituitary adenomas are examples of benign tumours which vary in size and aggressiveness. The present study was performed to investigate, via liquid biopsy and tissue analysis, the presence of K-RAS mutations in a pituitary macroadenoma., Methods: Molecular analysis was performed to investigate K-RAS mutations using the droplet digital PCR (ddPCR) method by evaluating both plasma (liquid biopsy) and the solid tumour of a patient diagnosed with a giant clinically non-functioning pituitary tumour., Results: The patient underwent surgical resection due to visual loss, and the histopathological analysis showed a gonadotrophic pituitary macroadenoma. The molecular analysis revealed the presence of mutant K-RAS both in the plasma and in the tumour tissue which, to our knowledge, has not been previously reported in the literature., Conclusion: Our findings highlight the exceptional capacity of the digital PCR in detecting low frequency mutations (below 1%), since we detected, for the first time, K-RAS mutations in pituitary macroadenoma. The potential impact of K-RAS mutations in these tumours should be further investigated., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)
- Published
- 2021
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8. ABC transporters and the hallmarks of cancer: roles in cancer aggressiveness beyond multidrug resistance.
- Author
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Muriithi W, Macharia LW, Heming CP, Echevarria JL, Nyachieo A, Filho PN, and Neto VM
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- Humans, Neoplastic Stem Cells, Tissue Distribution, ATP-Binding Cassette Transporters metabolism, Drug Resistance, Multiple physiology, Drug Resistance, Neoplasm physiology, Neoplasms physiopathology
- Abstract
The ATP-binding cassette transporters (ABC transporters) have been intensely studied over the past 50 years for their involvement in the multidrug resistance (MDR) phenotype, especially in cancer. They are frequently overexpressed in both naive and post-treatment tumors, and hinder effective chemotherapy by reducing drug accumulation in cancer cells. In the last decade however, several studies have established that ABC transporters have additional, fundamental roles in tumor biology; there is strong evidence that these proteins are involved in transporting tumor-enhancing molecules and/or in protein-protein interactions that impact cancer aggressiveness, progression, and patient prognosis. This review highlights these studies in relation to some well-described cancer hallmarks, in an effort to re-emphasize the need for further investigation into the physiological functions of ABC transporters that are critical for tumor development. Unraveling these new roles offers an opportunity to define new strategies and targets for therapy, which would include endogenous substrates or signaling pathways that regulate these proteins., (Copyright: © 2020, Cancer Biology & Medicine.)
- Published
- 2020
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9. Efficacy of reciprocating and ultrasonic activation of 6% sodium hypochlorite in the reduction of microbial content and virulence factors in teeth with primary endodontic infection.
- Author
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Aveiro E, Chiarelli-Neto VM, de-Jesus-Soares A, Zaia AA, Ferraz CCR, Almeida JFA, Marciano MA, Feres M, and Gomes BPFA
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- Dental Pulp Cavity, Humans, Root Canal Irrigants, Root Canal Preparation, Sodium Hypochlorite, Ultrasonics, Virulence Factors, Infections, Periapical Periodontitis
- Abstract
Aim: To evaluate in a clinical trial the efficacy of reciprocating and ultrasonic activation of 6% sodium hypochlorite (NaOCl) in the microbial composition and reduction in microbial load as well as in levels of lipopolysaccharide (LPS) and lipoteichoic acid (LTA) in teeth with primary endodontic infections., Methodology: Samples were collected from 24 root canals with pulp necrosis and periapical lesions, before and after chemo-mechanical canal preparation. The teeth were randomly divided according to the activation protocol as follows: control group without activation (WA, n = 8), reciprocating activation group using Easy Clean tip (EC, n = 8) and ultrasonic activation group using Irrisonic insert (US, n = 8). Microbiological specimens were processed using a culture technique and microbiota composition was analysed using the checkerboard technique. The levels of LPS and LTA were quantified using limulus amebocyte lysate (LAL) and enzyme-linked immunosorbent assay (ELISA), respectively. The Fisher's exact test, Kruskal-Wallis, Dunn's and Wilcoxon's test with a significance level of P < 0.05 were used for statistical analysis., Results: All initial specimens had growth of viable bacteria in fastidious anaerobe agar (FAA), with an average of 10
5 CFU mL-1 , whereas only one case had such growth after chemo-mechanical canal preparation. LPS and LTA were recovered in 100% of the cases. Chemo-mechanical canal preparation significantly decreased the levels of LPS and LTA (P < 0.05), but no significant differences were found between the groups (P > 0.05). Through the checkerboard technique, bacteria were found in 100% of the initial specimens with concentrations between <105 and 106 . The most frequently identified microorganisms were Prevotella nigrescens and Enterococcus hirae. After chemo-mechanical canal preparation, many species were not detected in any of the three groups tested. A significant reduction occurred in Group US, followed by Groups EC and WA., Conclusions: Activation of 6% NaOCl reduced the levels of LPS and LTA with no differences between the groups. However, ultrasonic activation was associated with a greater reduction in microbial load within root canals., (© 2019 International Endodontic Journal. Published by John Wiley & Sons Ltd.)- Published
- 2020
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10. Osteoarthritic Synovial Fluid Modulates Cell Phenotype and Metabolic Behavior In Vitro .
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de Sousa EB, Dos Santos Junior GC, Aguiar RP, da Costa Sartore R, de Oliveira ACL, Almeida FCL, Neto VM, and Aguiar DP
- Abstract
Synovial fluid holds a population of mesenchymal stem cells (MSC) that could be used for clinical treatment. Our goal was to characterize the inflammatory and metabolomic profile of the synovial fluid from osteoarthritic patients and to identify its modulatory effect on synovial fluid cells. Synovial fluid was collected from non-OA and OA patients, which was centrifuged to isolate cells. Cells were cultured for 21 days, characterized with specific markers for MSC, and exposed to a specific cocktail to induce chondrogenic, osteogenic, and adipogenic differentiation. Then, we performed a MTT assay exposing SF cells from non-OA and OA patients to a medium containing non-OA and OA synovial fluid. Synovial fluid from non-OA and OA patients was submitted to ELISA to evaluate BMP-2, BMP-4, IL-6, IL-10, TNF- α , and TGF- β 1 concentrations and to a metabolomic evaluation using
1 H-NMR. Synovial fluid cells presented spindle-shaped morphology in vitro . Samples from OA patients formed a higher number of colonies than the ones from non-OA patients. After 21 days, the colony-forming cells from OA patients differentiated into the three mesenchymal cell lineages, under the appropriated induction protocols. Synovial fluid cells increased its metabolic activity after being exposed to the OA synovial fluid. ELISA assay showed that OA synovial fluid samples presented higher concentration of IL-10 and TGF- β 1 than the non-OA, while the NMR showed that OA synovial fluid presents higher concentrations of glucose and glycerol. In conclusion, SFC activity is modulated by OA synovial fluid, which presents higher concentration of IL-10, TGF- β , glycerol, and glucose.- Published
- 2019
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11. ZIKA Virus and Neuroscience: the Need for a Translational Collaboration.
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Schuler-Faccini L, Roehe P, Zimmer ER, Quincozes-Santos A, de Assis AM, Lima EOC, Guimarães JA, Victora C, Neto VM, and Souza DO
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- Animals, Brazil, Disease Outbreaks, Humans, Neurosciences, Translational Research, Biomedical, Zika Virus, Zika Virus Infection
- Abstract
Zika virus (ZIKV) has become a major challenge for scientists and health agencies. ZIKV's involvement with human fetal microcephaly and Guillain-Barré syndrome and its transmission through Aedes africanus and Aedes aegypti mosquitos highlighted the epidemiological and neurological risks associated to ZIKV infection. In 2013, ZIKV arrives in Brazil but the first outbreak in the country was reported in 2015. Here, we used the Web of Science as a search tool for comparing the evolution of world and Brazilian scientific research on dengue virus (DENV)-also present in mosquito-, ZIKV and microcephaly. The association between ZIKV and microcephaly was only evidenced in 2015. Interestingly, Brazil and the USA are the responsible for most of these reports. Furthermore, the level of double-counted articles indicates a high degree of international collaborative effort in studying ZIKV and microcephaly. The ZIKV research clearly requires multidisciplinary expertise including epidemiologic, clinical, virological, and neurochemical backgrounds. This letter intends to emphasize the need of multidisciplinary studies and put forward some as yet unanswered questions in attempting to contribute to the understanding of this multifaceted health problem. In line with this, we recently constituted a collaborative and multidisciplinary taskforce encompassing eight Brazilian scientific institutions of excellence, The ZIKV translational research taskforce. This taskforce comprises a vast international network of collaborators and welcomes additional collaborators. We intend to advance fast in terms of mechanisms, which can potentially contribute to treat or halt ZIKV spreading around the world.
- Published
- 2018
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12. Clinical and laboratory profile of patients with sickle cell anemia.
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Sant'Ana PG, Araujo AM, Pimenta CT, Bezerra ML, Junior SP, Neto VM, Dias JS, Lopes AF, Rios DR, and Pinheiro MB
- Abstract
Objective: This study aimed to describe and analyze clinical and laboratory characteristics of patients with sickle cell anemia treated at the Hemominas Foundation, in Divinópolis, Brazil. Furthermore, this study aimed to compare the clinical and laboratory outcomes of the group of patients treated with hydroxyurea with those patients that were not treated with hydroxyurea., Methods: Clinical and laboratorial data were obtained by analyzing medical records of patients with sickle cell anemia., Results: Data from the medical records of 50 patients were analyzed. Most of the patients were female (56%), aged between 20 and 29 years old. Infections, transfusions, cholecystectomy, splenectomy and systemic arterial hypertension were the most common clinical adverse events of the patients. The most frequent cause of hospitalization was painful crisis. The majority of patients had reduced values of hemoglobin and hematocrit (8.55±1.33g/dL and 25.7±4.4%, respectively) and increased fetal hemoglobin levels (12±7%). None of the clinical variables was statistically significant on comparing the two groups of patients. Among hematological variables only hemoglobin and hematocrit levels were statistically different between patients treated with hydroxyurea and untreated patients (p-value=0.005 and p-value=0.001, respectively)., Conclusion: Sickle cell anemia requires treatment and follow-up by a multiprofessional team. A current therapeutic option is hydroxyurea. This drug reduces complications and improves laboratorial parameters of patients. In this study, the use of the drug increased the hemoglobin and hematocrit levels of patients., (Copyright © 2016 Associação Brasileira de Hematologia, Hemoterapia e Terapia Celular. Published by Elsevier Editora Ltda. All rights reserved.)
- Published
- 2017
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13. Immunohistochemical expression of sulfhydryl oxidase (QSOX1) in pediatric medulloblastomas.
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Sobral AC, Neto VM, Traiano G, Percicote AP, Gugelmin ES, de Souza CM, Nakao L, Torres LF, and de Noronha L
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- Adolescent, Apoptosis physiology, Cell Line, Tumor, Cerebellar Neoplasms pathology, Child, Child, Preschool, Extracellular Matrix enzymology, Extracellular Matrix pathology, Gene Expression Regulation, Neoplastic, Humans, Immunohistochemistry methods, Infant, Medulloblastoma pathology, Cerebellar Neoplasms enzymology, Medulloblastoma enzymology, Oxidoreductases Acting on Sulfur Group Donors metabolism
- Abstract
Background: Medulloblastoma is a malignant, invasive embryonal tumor of the cerebellum and accounts for 20% of intracranial tumors in children. QSOX1, whose functions include formation of disulphide bridges, which are needed for correct protein folding and stability, formation of the extracellular matrix, regulation of the redox status and cell cycle control, appears to be involved in apoptosis in pathological states such as cancer. Thus, the aim of this study was to investigate the immunohistochemical expression of QSOX1 in medulloblastomas and nonneoplastic cerebellum., Methods: Histology blocks of pediatric medulloblastomas were separated and two representative areas of the tumors and non-neoplastic cerebellum samples were used to construct tissue microarrays (TMAs) that were stained with an anti-QSOX1 antibody, and the slides were read using image analysis software., Results: QSOX1 immunoexpression was observed in the non-neoplastic cerebellum samples and the medulloblastoma samples. There was no statistically significant relationship between QSOX1 immunopositivity in the medulloblastoma samples and the clinical and pathological variables., Conclusions: Although QSOX1 did not prove useful for stratifying patients into risk groups, tumor cells and the fibrillar extracellular matrix were positive for this marker, indicating that this enzyme may be involved in the pathogenesis of medulloblastoma., Virtual Slides: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1822040654139436.
- Published
- 2015
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14. Glioblastoma cells: a heterogeneous and fatal tumor interacting with the parenchyma.
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Alves TR, Lima FR, Kahn SA, Lobo D, Dubois LG, Soletti R, Borges H, and Neto VM
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- Animals, Glioblastoma blood supply, Humans, Metalloproteases physiology, Neoplasm Invasiveness pathology, Neoplastic Stem Cells physiology, Neovascularization, Pathologic pathology, Nervous System Neoplasms blood supply, Pore Forming Cytotoxic Proteins metabolism, Glioblastoma pathology, Nervous System Neoplasms pathology
- Abstract
Glioblastomas (GBMs) are considered to be one of the deadliest human cancers, characterized by a high proliferative rate, aggressive invasiveness and insensitivity to radio- and chemotherapy, as well as a short patient survival period. Moreover, GBMs are among the most vascularized and invasive cancers in humans. Angiogenesis in GBMs is correlated with the grade of malignancy and is inversely correlated with patient survival. One of the first steps in tumor invasions is migration. GBM cells have the ability to infiltrate and disrupt physical barriers such as basement membranes, extracellular matrix and cell junctions. The invasion process includes the overexpression of several members of a super-family of zinc-based proteinases, the Metzincin, in particular a sub-group, metalloproteinases. Another interesting aspect is that, inside the GBM tissue, there are up to 30% of microglia or macrophages. However, little is known about the immune performance and interactions of the microglia with GBMs. These singular properties of GBMs will be described here. A sub-population of cells with stem-like properties may be the source of tumors since, apparently, GBM stem cells (GSCs) are highly resistant to current cancer treatments. These cancer therapies, while killing the majority of tumor cells, ultimately fail in GBM treatment because they do not eliminate GSCs, which survive to regenerate new tumors. Finally, GBM patient prognostic has shown little improvement in decades. In this context, we will discuss how the membrane-acting toxins called cytolysins can be a potential new tool for GBM treatment., (Copyright © 2011 Elsevier Inc. All rights reserved.)
- Published
- 2011
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15. Flavonoids: potential Wnt/beta-catenin signaling modulators in cancer.
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Amado NG, Fonseca BF, Cerqueira DM, Neto VM, and Abreu JG
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- Animals, Humans, Plants chemistry, Flavonoids pharmacology, Neoplasms physiopathology, Signal Transduction drug effects, Wnt Proteins drug effects, beta Catenin physiology
- Abstract
Flavonoids are polyphenolic compounds found throughout the plant kingdom. They occur in every organ but are usually concentrated in leaves and flowers. During the last two decades, in vitro and in vivo studies demonstrated that flavonoids have inhibitory effects on human diseases through targeting of multiple cellular signaling components. Wnt/β-catenin signaling regulates proliferation, differentiation and fate specification in developmental stages and controls tissue homeostasis in adult life. For these reasons, this pathway has received great attention in the last years as potential pathway involved in distinct Human pathologies. In this review we discuss the emerging potential mechanisms for flavonoids on Wnt/β-catenin signaling in cancer and possible investigation strategies to understand flavonoids mode of action on this signaling pathway., (Copyright © 2011 Elsevier Inc. All rights reserved.)
- Published
- 2011
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16. Neuron-glia signaling: Implications for astrocyte differentiation and synapse formation.
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Stipursky J, Romão L, Tortelli V, Neto VM, and Gomes FC
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- Animals, Glutamic Acid physiology, Humans, Intercellular Signaling Peptides and Proteins physiology, Neurodegenerative Diseases pathology, Neurotransmitter Agents physiology, Signal Transduction physiology, Transforming Growth Factor beta1 physiology, Astrocytes physiology, Cell Differentiation physiology, Neuroglia physiology, Neurons physiology, Synapses physiology
- Abstract
Glial cells are currently viewed as active partners of neurons in synapse formation. The close proximity of astrocytes to the synaptic cleft implicates that they strongly influence synapse function as well as suggests that these cells might be potential targets for neuronal-released molecules. In this review, we discuss the signaling pathways of astrocyte generation and the role of astrocyte-derived molecules in synapse formation in the central nervous system. Further, we discuss the role of the excitatory neurotransmitter, glutamate and transforming growth factor beta 1 (TGF-β1) pathway in astrocyte generation and differentiation. We provide evidence that astrocytes surrounding synapses are target of neuronal activity and shed light into the role of astroglial cells into neurological disorders associated with glutamate neurotoxicity., (Copyright © 2011 Elsevier Inc. All rights reserved.)
- Published
- 2011
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17. Neurofilament heavy subunit in cerebrospinal fluid: a biomarker of amyotrophic lateral sclerosis?
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Mendonça DM, Martins SC, Higashi R, Muscara MN, Neto VM, Chimelli L, and Martinez AM
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- Adult, Aged, Amyotrophic Lateral Sclerosis pathology, Female, Humans, Male, Middle Aged, Neurons cytology, Neurons metabolism, Spinal Cord cytology, Spinal Cord metabolism, Spinal Cord pathology, Tyrosine analogs & derivatives, Tyrosine metabolism, Amyotrophic Lateral Sclerosis cerebrospinal fluid, Amyotrophic Lateral Sclerosis diagnosis, Biomarkers cerebrospinal fluid, Neurofilament Proteins cerebrospinal fluid, Protein Subunits cerebrospinal fluid
- Abstract
The objectives of this study were to investigate the presence of the three neurofilament subunits, ubiquitin, proteasome and 3-nitrotyrosine, in CSF samples of ALS patients. CSF samples were obtained by lumbar puncture from 10 ALS patients and six controls. All samples were analysed by Western blotting. Results revealed that neurofilament heavy subunit was identified in 70% of ALS cases and we conclude that this subunit may be a promising biomarker for clinical diagnosis of ALS.
- Published
- 2011
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18. Isoquercitrin isolated from Hyptis fasciculata reduces glioblastoma cell proliferation and changes beta-catenin cellular localization.
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Amado NG, Cerqueira DM, Menezes FS, da Silva JF, Neto VM, and Abreu JG
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- Antineoplastic Agents, Phytogenic administration & dosage, Antineoplastic Agents, Phytogenic isolation & purification, Cell Cycle drug effects, Cell Line, Tumor, Cell Proliferation drug effects, Cyclin D1 drug effects, Cyclin D1 metabolism, Cyclin-Dependent Kinase Inhibitor p27 drug effects, Cyclin-Dependent Kinase Inhibitor p27 metabolism, Dose-Response Relationship, Drug, Glioblastoma physiopathology, Humans, Quercetin administration & dosage, Quercetin isolation & purification, Quercetin pharmacology, Rutin administration & dosage, Rutin pharmacology, Time Factors, beta Catenin metabolism, Antineoplastic Agents, Phytogenic pharmacology, Glioblastoma drug therapy, Hyptis chemistry, Quercetin analogs & derivatives
- Abstract
Isoquercitrin isolated from the aerial parts of Hyptis fasciculata was evaluated according to its capacity to interfere with glioblastoma (Gbm) cell growth. Gbm cells were incubated with isoquercitrin, quercetin, or rutin at concentrations of 25, 50, and 100 mumol/l for 24, 48, and 72 h. Quercetin and rutin affected Gbm cell proliferation after treatment times of longer than 24 h. However, increasing concentrations of isoquercitrin inhibited 50% of Gbm cell proliferation at 24 h and further reached nearly 90% inhibition at 72 h. This effect did not affect cell morphology, cell viability, or cleaved capase-3 levels, indicating that isoquercitrin did not induce Gbm cell death. A marked reduction in cyclin D1 levels and an increase in p27 levels were observed when 100 micromol/l of isoquercitrin was added to Gbm cells. Interestingly, nuclear beta-catenin staining observed in a subpopulation of untreated Gbm cells was found in the cytoplasm after 100-micromol/l isoquercitrin treatment. Collectively, these data show that isoquercitrin reduces Gbm cell growth without inducing apoptosis, possibly by modulating the control of the cell cycle. Our data also suggest that beta-catenin-mediated signaling may be involved on the antiproliferative activity of isoquercitrin.
- Published
- 2009
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19. Differences in the expression pattern of P-glycoprotein and MRP1 in low-grade and high-grade gliomas.
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de Faria GP, de Oliveira JA, de Oliveira JG, Romano Sde O, Neto VM, and Maia RC
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- Adolescent, Adult, Aged, Child, Child, Preschool, Female, Glioma drug therapy, Glioma metabolism, Humans, Immunohistochemistry, Male, Middle Aged, Neoplasm Staging, Young Adult, ATP Binding Cassette Transporter, Subfamily B, Member 1 biosynthesis, Glioma pathology, Multidrug Resistance-Associated Proteins biosynthesis
- Abstract
Multidrug resistance in gliomas is the major challenges in the clinical setting. We investigated the expression of P-glycoprotein (Pgp) and multidrug resistance-related protein 1 (MRP1) in 50 gliomas using immunohistochemistry. Compared to Pgp, MRP1 positivity was observed in highest percentage of gliomas grade IV samples (p = 0.008). Unlike MRP1 expression observed in high-grade, gliomas grade II exhibited a greater number of Pgp positive samples as compared to grades III and IV (p = 0.026). Our results suggest that the difference between the histological grade gliomas regarding MRP1 and Pgp expression must have implications in the choice of chemotherapeutic protocols.
- Published
- 2008
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20. Glutamate activates GFAP gene promoter from cultured astrocytes through TGF-beta1 pathways.
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Romão LF, Sousa Vde O, Neto VM, and Gomes FC
- Subjects
- Animals, Astrocytes ultrastructure, Brain cytology, Cells, Cultured, Culture Media, Conditioned pharmacology, Dose-Response Relationship, Drug, Embryo, Mammalian, Enzyme Inhibitors pharmacology, Excitatory Amino Acid Antagonists pharmacology, Gene Expression Regulation drug effects, Glial Fibrillary Acidic Protein metabolism, Mice, Mice, Transgenic, Neurons chemistry, Promoter Regions, Genetic physiology, Synaptosomes drug effects, Synaptosomes metabolism, Transcriptional Activation, Transforming Growth Factor beta pharmacology, beta-Galactosidase metabolism, Astrocytes drug effects, Glial Fibrillary Acidic Protein genetics, Glutamic Acid pharmacology, Promoter Regions, Genetic drug effects, Signal Transduction drug effects, Transforming Growth Factor beta metabolism
- Abstract
Glial cells are currently viewed as active partners of neurons in synapse formation. The close proximity of astrocytes to the synaptic cleft suggests that these cells might be potential targets for neuronal-released molecules although this issue has been less addressed. Here, we evaluated the role of the excitatory neurotransmitter, glutamate, in astrocyte differentiation. We recently demonstrated that cortical neurons activate the gene promoter of the astrocyte maturation marker, GFAP (glial fibrillary acidic protein) of cerebral cortex astrocytes by inducing TGF-beta1 (transforming growth factor beta 1) secretion in vitro. To access the effect of glutamate on GFAP gene, we used transgenic mice bearing the beta-Galactosidase (beta-Gal) reporter gene under the regulation of the GFAP gene promoter. We report that 100 muM glutamate activates the GFAP gene promoter of astrocytes from cerebral cortex revealed by a significant increase in the number of beta-Gal positive astrocytes. Neutralizing antibodies against TGF-beta completely prevented glutamate and neuronal-induction of GFAP gene, thus indicating that this event is mediated by TGF-beta1. Further, induction of GFAP gene in response to glutamate was followed by nuclear translocation of the Smad transcription factor, a hallmark of TGF-beta1 pathway activation. The antagonist of the metabotropic glutamate receptor, MCPG, inhibited neuronal effect suggesting that neuronal activation of GFAP gene promoter involves glutamate metabotropic receptors. MAPK (PD98059) and PI3K (LY294002) inhibitors fully prevented activation of GFAP gene promoter by all treatments. Surprisingly, these inhibitors also abrogated TGF-beta1 direct action on GFAP gene although they did not inhibit Smad-2 phosphorylation, suggesting that TGF-beta1-induced GFAP gene activation might involve cooperation between the canonical and non-canonical TGF-beta pathways. Together, our results suggest that glial metabotropic glutamate 2/3 receptor activation by neurons induces TGF-beta1 secretion, leading to GFAP gene activation and astrocyte differentiation and involves Smad and MAPK/PI3K pathways. Our work provides evidence that astrocytes surrounding synapses are target of neuronal activity and might shed light into the role of glial cells into neurological disorders associated with glutamate neurotoxicity.
- Published
- 2008
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- View/download PDF
21. Structure and elastic properties of tunneling nanotubes.
- Author
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Pontes B, Viana NB, Campanati L, Farina M, Neto VM, and Nussenzveig HM
- Subjects
- Actins metabolism, Cell Line, Tumor, Elasticity, Glioblastoma pathology, Humans, Microscopy, Electron, Scanning, Microspheres, Optical Tweezers, Stress, Mechanical, Cell Communication
- Abstract
We investigate properties of a reported new mechanism for cell-cell interactions, tunneling nanotubes (TNT's). TNT's mediate actin-based transfer of vesicles and organelles and they allow signal transmission between cells. The effects of lateral pulling with polystyrene beads trapped by optical tweezers on TNT's linking separate U-87 MG human glioblastoma cells in culture are described. This cell line was chosen for handling ease and possible pathology implications of TNT persistence in communication between cancerous cells. Observed nanotubes are shown to have the characteristic features of TNT's. We find that pulling induces two different types of TNT bifurcations. In one of them, termed V-Y bifurcation, the TNT is first distorted into a V-shaped form, following which a new branch emerges from the apex. In the other one, termed I-D bifurcation, the pulled TNT is bent into a curved arc of increasingly broader span. Curves showing the variation of pulling force with displacement are obtained. Results yield information on TNT structure and elastic properties.
- Published
- 2008
- Full Text
- View/download PDF
22. Sensitivity to microcystins: a comparative study in human cell lines with and without multidrug resistance phenotype.
- Author
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de Souza Votto AP, Renon VP, Yunes JS, Rumjanek VM, Marques Capella MA, Neto VM, Sampaio de Freitas M, Alicia Geracitano L, Monserrat JM, and Trindade GS
- Subjects
- Cell Line, Tumor, Humans, K562 Cells, Metabolic Networks and Pathways, Tubulin metabolism, Drug Resistance, Multiple, Drug Resistance, Neoplasm, Microcystins pharmacology, Oxidants pharmacology, Reactive Oxygen Species metabolism
- Abstract
Multidrug resistance (MDR) is an obstacle in cancer treatment. An understanding of how tumoral cells react to oxidants can help us elucidate the cellular mechanism involved in resistance. Microcystins are cyanobacteria hepatotoxins known to generate oxidative stress. The aim of this study was to compare the sensitivity to microcystins of human tumoral cell lines with (Lucena) and without (K562) MDR phenotype. Endpoints analyzed were effective microcystins concentration to 50% of exposed cells (EC50), antioxidant enzyme activity, lipid peroxidation, DNA damage, reactive oxygen species (ROS) concentration, and tubulin content. Lucena were more resistant and showed lower DNA damage than K562 cells (P<0.05). Although microcystins did not alter catalase activity, a higher mean value was observed in Lucena than in K562 cells. Lucena cells also showed lower ROS concentration and higher tubulin content. The higher metabolism associated with the MDR phenotype should increase ROS concentration and make for an improved antioxidant defense against the toxic effects of microcystins.
- Published
- 2007
- Full Text
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23. Exposure of C6 glioma cells to Pb(II) increases the phosphorylation of p38(MAPK) and JNK1/2 but not of ERK1/2.
- Author
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Posser T, de Aguiar CB, Garcez RC, Rossi FM, Oliveira CS, Trentin AG, Neto VM, and Leal RB
- Subjects
- Animals, Brain Neoplasms pathology, Cell Line, Tumor, Cell Survival drug effects, Dose-Response Relationship, Drug, Glioma pathology, Mitogen-Activated Protein Kinase 1 metabolism, Mitogen-Activated Protein Kinase 3 metabolism, Phosphorylation, Rats, Time Factors, Brain Neoplasms enzymology, Environmental Pollutants toxicity, Glioma enzymology, MAP Kinase Signaling System drug effects, Mitogen-Activated Protein Kinase 8 metabolism, Mitogen-Activated Protein Kinase 9 metabolism, Organometallic Compounds toxicity, p38 Mitogen-Activated Protein Kinases metabolism
- Abstract
Pb(II) is a neurotoxic pollutant that produces permanent cognitive deficits in children. Pb(II) can modulate cell signaling pathways and cell viability in a variety of cell types. However, these actions are not well demonstrated on glial cells, which represent an important target for metals into the central nervous system. The present work was undertaken to determine the ability of Pb(II) in modulating the activity of mitogen activated protein kinases (MAPKs) in cultures of C6 rat glioma cells, a useful functional model for the study of astrocytes. Additionally, cell viability was analyzed by measurement of MTT reduction. Cells were exposed to lead acetate 0.1, 1, 10 microM for 24 and 48 h. MAPKs activation - in particular ERK1/2, p38(MAPK) and JNK1/2 - were analyzed by western blotting. Results showed that 10 microM Pb(II) treatment for 24 h caused a discrete stimulation of p38(MAPK) phosphorylation. However, 1 and 10 microM Pb(II) treatment for 48 h provoked a significant stimulation in the phosphorylation state of p38(MAPK) and JNK1/2. The phosphorylation state of ERK1/2 was not modified by any Pb(II) treatment. Moreover, data indicate that at 48 h treatment even 1 microM Pb(II) can be cytotoxic, causing impairment on cell viability. Therefore, depending on a long incubation period, a significant concomitant activation of p38(MAPK) and JNK1/2 by Pb(II) took place in parallel with the impairment of C6 glioma cells viability.
- Published
- 2007
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24. Dopamine affects the stability, hydration, and packing of protofibrils and fibrils of the wild type and variants of alpha-synuclein.
- Author
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Follmer C, Romão L, Einsiedler CM, Porto TC, Lara FA, Moncores M, Weissmüller G, Lashuel HA, Lansbury P, Neto VM, Silva JL, and Foguel D
- Subjects
- Amino Acid Substitution, Dopamine metabolism, Drug Stability, Genetic Variation, Humans, Hydrostatic Pressure, In Vitro Techniques, Microscopy, Atomic Force, Microscopy, Electron, Multiprotein Complexes, Neurons metabolism, Parkinson Disease etiology, Parkinson Disease metabolism, Recombinant Proteins chemistry, Recombinant Proteins drug effects, Recombinant Proteins genetics, Recombinant Proteins metabolism, Water chemistry, alpha-Synuclein drug effects, alpha-Synuclein genetics, Dopamine pharmacology, alpha-Synuclein chemistry, alpha-Synuclein metabolism
- Abstract
Parkinson's disease (PD) is characterized by the presence of cytoplasmic inclusions composed of alpha-synuclein (alpha-syn) in dopaminergic neurons. This suggests a pivotal role of dopamine (DA) on PD development. Here, we show that DA modulates differently the stability of protofibrils (PF) and fibrils (F) composed of wild type or variants of alpha-syn (A30P and A53T) as probed by high hydrostatic pressure (HHP). While in the absence of DA, all alpha-syn PF exhibited identical stability, in its presence, the variant-composed PF acquired a greater stability (DAPFwt < DAPFA30P = DAPFA53T), implying that they would last longer, which could shed light onto why these mutations are so aggressive. When alpha-syn was incubated for long times (18 days) in the presence of DA, we observed the formation of F by electronic microscopy, suggesting that the PF trapped in the presence of DA in short times can evolve into F. The stability of F was also altered by DA. DAFwt was more labile than Fwt, indicating that the former would be more susceptible to breakage. PFA30P and DAPFA30P, when added to mesencephalic and cortical neurons in culture, decreased the number and length of neurites and increased the number of apoptotic cells. Surprisingly, these toxic effects of PFA30P and DAPFA30P were practically abolished with HHP treatment, which was able to break the PF into smaller aggregates, as seen by atomic force microscopy. These results suggest that strategies aimed at breaking and/or clearing these aggregates is promising in alleviating the symptoms of PD.
- Published
- 2007
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25. Neuritogenesis and neuronal differentiation promoted by 2,4-dinitrophenol, a novel anti-amyloidogenic compound.
- Author
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Wasilewska-Sampaio AP, Silveira MS, Holub O, Goecking R, Gomes FC, Neto VM, Linden R, Ferreira ST, and De Felice FG
- Subjects
- Amyloid beta-Peptides chemistry, Animals, Blotting, Western, Cell Differentiation, Cell Line, Cell Line, Tumor, Cerebral Cortex pathology, Cyclic AMP metabolism, Dose-Response Relationship, Drug, Extracellular Signal-Regulated MAP Kinases metabolism, Hippocampus cytology, Hippocampus embryology, MAP Kinase Signaling System, Mice, Microscopy, Fluorescence, Neurodegenerative Diseases pathology, Oxygen metabolism, Oxygen Consumption, Peptide Fragments chemistry, Rats, Reactive Oxygen Species, Time Factors, Uncoupling Agents pharmacology, tau Proteins chemistry, 2,4-Dinitrophenol pharmacology, Amyloid chemistry, Neurites pathology, Neurons metabolism
- Abstract
Neurite outgrowth is a critical event in neuronal development, formation, and remodeling of synapses, response to injury, and regeneration. We examined the effects of 2,4-dinitrophenol (DNP), a recently described blocker of the aggregation and neurotoxicity of the beta-amyloid peptide, on neurite elongation of central neurons. Morphometric analysis of rat embryo hippocampal and cortical neuronal cultures showed that neurite outgrowth was stimulated by DNP. This effect was accompanied by increases in the neuronal levels of the microtubule-associated protein tau and of cyclic adenosine 3',5' monophosphate (cAMP). DNP also promoted cAMP accumulation, increased tau level, neurite outgrowth, and neuronal differentiation in the mouse neuroblastoma cell line N2A. We show that DNP-induced differentiation requires activation of the extracellular signal-regulated kinase (ERK). The finding that DNP promotes neuritogenesis and neuronal differentiation suggests that, in addition to its anti-amyloidogenic actions, it may be a useful lead compound in the development of novel therapeutic approaches targeting neurite dystrophy and synaptic dysfunction in neurodegenerative pathologies such as Alzheimer's disease.
- Published
- 2005
- Full Text
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26. The end of a Chilean institute.
- Author
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Barbeito L, Chun J, Binder LI, Neto VM, Perry G, Scazzochio C, and Violini G
- Subjects
- Chile, Financing, Government, Academies and Institutes, Biology, Biotechnology, Cell Physiological Phenomena, Financial Support
- Published
- 2005
- Full Text
- View/download PDF
27. Congenital hypothyroidism alters the phosphorylation of ERK1/2 and p38MAPK in the hippocampus of neonatal rats.
- Author
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Calloni GW, Penno CA, Cordova FM, Trentin AG, Neto VM, and Leal RB
- Subjects
- Animals, Animals, Newborn, Cell Differentiation genetics, Congenital Hypothyroidism enzymology, Congenital Hypothyroidism genetics, Congenital Hypothyroidism physiopathology, Disease Models, Animal, Down-Regulation genetics, Female, Hippocampus growth & development, Hippocampus physiopathology, Hypothyroidism physiopathology, JNK Mitogen-Activated Protein Kinases metabolism, Male, Memory Disorders genetics, Memory Disorders physiopathology, Mitogen-Activated Protein Kinase 1 metabolism, Mitogen-Activated Protein Kinase 3 metabolism, Phosphorylation, Rats, Rats, Wistar, Up-Regulation genetics, p38 Mitogen-Activated Protein Kinases metabolism, Genetic Predisposition to Disease genetics, Hippocampus enzymology, Hypothyroidism complications, MAP Kinase Signaling System physiology, Memory Disorders enzymology
- Abstract
Thyroid hormone deficiency during the critical period of neural differentiation produces permanent and severe alterations in the morphology and function of the nervous system leading to cretinism. Perinatal hypothyroidism results in permanent alterations of hippocampal synaptic functions in adult rats consequently causing learning and memory impairment. Mitogen-activated protein kinases (MAPKs) are a family of protein kinases that regulate essential cellular activities ranging from gene expression, mitosis, programmed cell death to plasticity and memory formation, but their involvement in perinatal hypothyroidism is not determined. The present work was designed to investigate MAPKs phosphorylation in hippocampus of congenital neonatal hypothyroid rats. Congenital hypothyroidism promotes an increase in extracellular signal-regulated kinases 1/2 (ERK 1/2) phosphorylation (+50%) and a decrease in p38(MAPK) phosphorylation (-50%) without changing in Jun N-terminal kinases (JNK) phosphorylation. Therefore, the congenital hypothyroidism model disturbs ERK 1/2 and p38(MAPK) phosphorylation pathways causing an important molecular alteration in the hippocampus. This event might be related, at least partially, to the deficits in hippocampal development and cognitive functions due neonatal congenital hypothyroidism.
- Published
- 2005
- Full Text
- View/download PDF
28. Sialic acid residues on astrocytes regulate neuritogenesis by controlling the assembly of laminin matrices.
- Author
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Freire E, Gomes FC, Jotha-Mattos T, Neto VM, Silva Filho FC, and Coelho-Sampaio T
- Subjects
- Aging metabolism, Animals, Animals, Newborn, Astrocytes drug effects, Cell Communication physiology, Cell Differentiation physiology, Cell Membrane drug effects, Cell Membrane physiology, Cells, Cultured, Cerebral Cortex growth & development, Cholesterol metabolism, Extracellular Matrix metabolism, G(M1) Ganglioside metabolism, G(M1) Ganglioside pharmacology, Gangliosides metabolism, Gangliosides pharmacology, Membrane Microdomains drug effects, Membrane Microdomains metabolism, Membrane Potentials physiology, Neuraminidase metabolism, Neuraminidase pharmacology, Neurites ultrastructure, Polymers metabolism, Rats, beta-Cyclodextrins pharmacology, Astrocytes metabolism, Cerebral Cortex cytology, Cerebral Cortex embryology, Laminin metabolism, N-Acetylneuraminic Acid metabolism, Neurites metabolism
- Abstract
In the developing nervous system migrating neurons and growing axons are guided by diffusible and/or substrate-bound cues, such as extracellular matrix-associated laminin. In a previous work we demonstrated that laminin molecules could self-assemble in two different manners, giving rise to matrices that could favor either neuritogenesis or proliferation of cortical precursor cells. We investigated whether the ability of astrocytes to promote neuritogenesis of co-cultivated neurons was modulated by the assembling mode of the laminin matrix secreted by them. We compared the morphologies and neuritogenic potentials of laminin deposited by in vitro-differentiated astrocytes obtained from embryonic or neonatal rat brain cortices. We showed that, while permissive astrocytes derived from embryonic brain produced a flat laminin matrix that remained associated to the cell surface, astrocytes derived from newborn brain secreted a laminin matrix resembling a fibrillar web that protruded from the cell plane. The average neurite lengths obtained for E16 neurons cultured on each astrocyte layer were 198+/-22 and 123+/-13 microm, respectively. Analyses of surface-associated electrostatic potentials revealed that embryonic astrocytes presented a pI of -2.8, while in newborn cells this value was -3.8. Removal of the sialic acid groups on the embryonic monolayer by neuraminidase treatment led to the immediate release of matrix-associated laminin. Interestingly, laminin reassembled 1 hour after neuraminidase removal converted to the features of the newborn matrix. Alternatively, treatment of astrocytes with the cholesterol-solubilizing detergent methyl-beta-cyclodextrin also resulted in release of the extracellular laminin. To test the hypothesis that sialic-acid-containing lipids localized at cholesterol-rich membrane domains could affect the process of laminin assembly, we devised a cell-free assay where laminin polymerization was carried out over artificial lipid films. Films of either a mixture of gangliosides or pure ganglioside GT1b induced formation of matrices of morpho-functional features similar to the matrices deposited by embryonic astrocytes. Conversely, films of phosphatidylcholine or ganglioside GM1 led to the formation of bulky laminin aggregates that lacked a defined structure. We propose that the expression of negative lipids on astrocytes can control the extracellular polymerization of laminin and, consequently, the permissivity to neuritogenesis of astrocytes during development.
- Published
- 2004
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29. Glial fibrillary acidic protein gene promoter is differently modulated by transforming growth factor-beta 1 in astrocytes from distinct brain regions.
- Author
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Sousa Vde O, Romão L, Neto VM, and Gomes FC
- Subjects
- Animals, Animals, Newborn, Astrocytes drug effects, Blotting, Western methods, Brain drug effects, Cell Count methods, Cells, Cultured, Coculture Techniques methods, Culture Media, Conditioned pharmacology, Embryo, Mammalian, Epidermal Growth Factor pharmacology, Fibroblast Growth Factors pharmacology, Glial Fibrillary Acidic Protein metabolism, Immunohistochemistry methods, Mice, Mice, Transgenic, Neurons drug effects, Neurons metabolism, Transforming Growth Factor beta1, Tubulin metabolism, beta-Galactosidase metabolism, Astrocytes metabolism, Brain cytology, Glial Fibrillary Acidic Protein genetics, Promoter Regions, Genetic physiology, Transforming Growth Factor beta physiology
- Abstract
The expression of glial fibrillary acidic protein (GFAP), the major intermediate filament protein of mature astrocytes, is regulated under developmental and pathological conditions. Recently, we have investigated GFAP gene modulation by using a transgenic mouse bearing part of the GFAP gene promoter linked to the beta-galactosidase reporter gene. We demonstrated that cerebral cortex neurons activate the GFAP gene promoter, inducing transforming growth factor-beta 1 (TGF-beta 1) secretion by astrocytes. Here, we report that cortical neurons or conditioned medium derived from them do not activate the GFAP gene promoter of transgenic astrocytes derived from midbrain and cerebellum suggesting a neuroanatomical regional specificity of this phenomenon. Surprisingly, they do induce synthesis of TGF-beta 1 by these cells. Western blot and immunocytochemistry assays revealed wild distribution of TGF receptor in all subpopulations of astrocytes and expression of TGF-beta 1 in neurons derived from all regions, thus indicating that the unresponsiveness of the cerebellar and midbrain GFAP gene to TGF-beta 1 is not due to a defect in TGF-beta 1 signalling. Together, our data highlight the great complexity of neuron-glia interactions and might suggest a distinct mechanism underlying modulation of the GFAP gene in the heterogeneous population of astrocytes throughout the central nervous system.
- Published
- 2004
- Full Text
- View/download PDF
30. Differences in the activation of the GFAP gene promoter by prion and viral infections.
- Author
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Titeux M, Galou M, Gomes FC, Dormont D, Neto VM, and Paulin D
- Subjects
- Animals, Astrocytes cytology, Astrocytes physiology, Brain anatomy & histology, Brain metabolism, Central Nervous System Viral Diseases metabolism, Genes, Reporter, Glial Fibrillary Acidic Protein metabolism, Herpesvirus 1, Suid genetics, Herpesvirus 1, Suid metabolism, Humans, Mice, Mice, Inbred C57BL, Mice, Transgenic, Prion Diseases metabolism, Theilovirus genetics, Theilovirus metabolism, Transgenes, Central Nervous System Viral Diseases genetics, Gene Expression Regulation, Glial Fibrillary Acidic Protein genetics, Prion Diseases genetics, Promoter Regions, Genetic
- Abstract
The expression of glial fibrillary acidic protein (GFAP), a component of astroglial intermediate filaments, is regulated under developmental and pathological conditions. After surgical injury or viral infections, an increase in this protein reflects reactive gliosis in the brain. We analyzed the activation of the GFAP gene in transgenic mice using a prion and two different viruses (rabies and Theiler viruses). Inoculation of the transgenic mice with the C506M3 mouse prion strain resulted in activation of the GFAP-lacZ transgene. Expression of the GFAP transgene increased concomitantly with the expression of GFAP in astrocytes from the infected mice. In contrast, infection with rabies or Theiler's virus had no effect on the expression of the GFAP transgene, showing that the glial reactions to these infectious agents involved different mechanisms. These findings indicate that the activation of the endogenous GFAP gene as a consequence of viral infection could involve different regulatory pathways than activation as a result of prion infection. The first 2 kb upstream from the start codon of the GFAP gene seems to provide enough activation domains to produce efficient activation of the reporter gene in prion-infected mice.
- Published
- 2002
- Full Text
- View/download PDF
31. Structure of laminin substrate modulates cellular signaling for neuritogenesis.
- Author
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Freire E, Gomes FC, Linden R, Neto VM, and Coelho-Sampaio T
- Subjects
- Animals, Cells, Cultured, Enzyme Inhibitors pharmacology, Hydrogen-Ion Concentration, Immunohistochemistry, Mice, Neurons cytology, Neurons drug effects, Protein Kinase Inhibitors, Rats, Rats, Wistar, Scattering, Radiation, Spectrometry, Fluorescence, Substrate Specificity, Laminin metabolism, Neurites, Signal Transduction
- Abstract
Laminin, a major component of basement membranes, can self-assemble in vitro into a typical mesh-like structure, according to a mass-action-driven process. Previously, we showed that pH acidification dramatically increased the efficiency of laminin self-assembly, practically abolishing the necessity for a minimal protein concentration. Here we have characterized the morphologies of laminin matrices produced in either neutral or acidic conditions and compared their capacities to induce neuritogenesis of rat embryonic cortical neurons. Although laminin matrices formed in neutral buffer presented aggregates of heterogeneous morphology, the acidic matrix consisted of a homogeneous hexagonal sheet-like structure. The latter was comparable to the matrix assembled in vivo at the inner limiting membrane of the retina in newborn rats, shown here, and to matrices secreted by cultivated cells, shown elsewhere. The average neurite length of cortical neurons plated on acidic matrices was 244.9 micro m, whereas on neutral matrices this value dropped to 104.1 micro m. Increased neuritogenesis on the acidic matrix seemed to be associated with a higher degree of neuronal differentiation, since cell proliferation was immediately arrested upon plating, whereas on neutral matrices, the cell number increased six-fold within 24 hours. Investigation of the mechanisms mediating neurite outgrowth on each condition revealed that the extensive neuritogenesis observed on the acidic matrix involved activation of protein kinase A, whereas moderate neuritogenesis on neutral laminin was mediated by activation of protein kinase C and/or myosin light-chain kinase. Explants of cerebral cortex from P2 rats did not grow on the neutral laminin substrate but presented extensive cell migration and neurite outgrowth on the acidic laminin matrix. We propose that laminin can self-assemble independently of cell contact and that the assembling mode differentially modulates neuritogenesis and neuroplasticity.
- Published
- 2002
- Full Text
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32. Neuro-glia interaction effects on GFAP gene: a novel role for transforming growth factor-beta1.
- Author
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de Sampaio e Spohr TC, Martinez R, da Silva EF, Neto VM, and Gomes FC
- Subjects
- Animals, Animals, Newborn, Astrocytes cytology, Astrocytes drug effects, Brain embryology, Brain growth & development, Cell Communication drug effects, Cell Differentiation drug effects, Cells, Cultured, Cellular Senescence drug effects, Cellular Senescence genetics, Epidermal Growth Factor metabolism, Epidermal Growth Factor pharmacology, Fetus, Fibroblast Growth Factor 2 metabolism, Fibroblast Growth Factor 2 pharmacology, Gene Expression Regulation, Developmental drug effects, Gene Expression Regulation, Developmental physiology, Glial Fibrillary Acidic Protein genetics, Mice, Mice, Transgenic, Neurites drug effects, Neurites metabolism, Neurites ultrastructure, Neurons cytology, Neurons drug effects, Promoter Regions, Genetic genetics, Transforming Growth Factor beta pharmacology, Transforming Growth Factor beta1, Astrocytes metabolism, Brain metabolism, Cell Communication genetics, Cell Differentiation genetics, Glial Fibrillary Acidic Protein metabolism, Neurons metabolism, Transforming Growth Factor beta metabolism
- Abstract
Central nervous system (CNS) development is highly guided by microenvironment cues specially provided by neuron-glia interactions. By using a transgenic mouse bearing part of the gene promoter of the astrocytic maturation marker GFAP (glial fibrillary acidic protein) linked to the beta-galactosidase (beta-Gal) reporter gene, we previously demonstrated that cerebral cortical neurons increase transgenic beta-Gal astrocyte number and activate GFAP gene promoter by secretion of soluble factors in vitro. Here, we identified TGF-beta1 as the major mediator of this event. Identification of TGF-beta1 in neuronal and astrocyte extracts revealed that both cell types might synthesize this factor, however, addition of neurons to astrocyte monolayers greatly increased TGF-beta1 synthesis and secretion by astrocytes. Further, by exploiting the advantages of cell culture system we investigated the influence of neuron and astrocyte developmental stage on such interaction. We demonstrated that younger neurons derived from 14 embryonic days wild-type mice were more efficient in promoting astrocyte differentiation than those derived from 18 embryonic days mice. Similarly, astrocytes also exhibited timed-schedule developed responsiveness to neuronal influence with embryonic astrocytes being more responsive to neurons than newborn and late postnatal astrocytes. RT-PCR assays identified TGF-beta1 transcripts in young but not in old neurons, suggesting that inability to induce astrocyte differentiation is related to TGF-beta1 synthesis and secretion. Our work reveals an important role for neuron-glia interactions in astrocyte development and strongly implicates the involvement of TGF-beta1 in this event.
- Published
- 2002
- Full Text
- View/download PDF
33. Inhibition of Alzheimer's disease beta-amyloid aggregation, neurotoxicity, and in vivo deposition by nitrophenols: implications for Alzheimer's therapy.
- Author
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De Felice FG, Houzel JC, Garcia-Abreu J, Louzada PR Jr, Afonso RC, Meirelles MN, Lent R, Neto VM, and Ferreira ST
- Subjects
- Alzheimer Disease drug therapy, Amyloid beta-Peptides chemistry, Animals, Cells, Cultured, Hippocampus cytology, Hippocampus metabolism, Humans, Microinjections, Neurons cytology, Neurons metabolism, Protein Structure, Tertiary, Rats, Alzheimer Disease metabolism, Amyloid beta-Peptides metabolism, Hippocampus drug effects, Neurons drug effects, Neuroprotective Agents pharmacology, Nitrophenols pharmacology
- Published
- 2001
- Full Text
- View/download PDF
34. Regulation of microglial development: a novel role for thyroid hormone.
- Author
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Lima FR, Gervais A, Colin C, Izembart M, Neto VM, and Mallat M
- Subjects
- Animals, Brain cytology, Brain drug effects, Brain growth & development, Cell Count, Cell Division drug effects, Cell Survival drug effects, Cells, Cultured, Female, Hyperthyroidism chemically induced, Hyperthyroidism metabolism, Hypothyroidism chemically induced, Hypothyroidism metabolism, Iodine deficiency, Methylthiouracil pharmacology, Microglia cytology, Microglia drug effects, Pregnancy, Prenatal Exposure Delayed Effects, Rats, Rats, Wistar, Receptors, Thyroid Hormone biosynthesis, Reverse Transcriptase Polymerase Chain Reaction, Thyroid Hormones pharmacology, Triiodothyronine metabolism, Triiodothyronine pharmacology, Microglia metabolism, Thyroid Hormones metabolism
- Abstract
The postnatal development of rat microglia is marked by an important increase in the number of microglial cells and the growth of their ramified processes. We studied the role of thyroid hormone in microglial development. The distribution and morphology of microglial cells stained with isolectin B4 or monoclonal antibody ED1 were analyzed in cortical and subcortical forebrain regions of developing rats rendered hypothyroid by prenatal and postnatal treatment with methyl-thiouracil. Microglial processes were markedly less abundant in hypothyroid pups than in age-matched normal animals, from postnatal day 4 up to the end of the third postnatal week of life. A delay in process extension and a decrease in the density of microglial cell bodies, as shown by cell counts in the developing cingulate cortex of normal and hypothyroid animals, were responsible for these differences. Conversely, neonatal rat hyperthyroidism, induced by daily injections of 3,5,3'-triiodothyronine (T3), accelerated the extension of microglial processes and increased the density of cortical microglial cell bodies above physiological levels during the first postnatal week of life. Reverse transcription-PCR and immunological analyses indicated that cultured cortical ameboid microglial cells expressed the alpha1 and beta1 isoforms of nuclear thyroid hormone receptors. Consistent with the trophic and morphogenetic effects of thyroid hormone observed in situ, T3 favored the survival of cultured purified microglial cells and the growth of their processes. These results demonstrate that thyroid hormone promotes the growth and morphological differentiation of microglia during development.
- Published
- 2001
35. Patterns of synthesis and secretion of sulfated glycosaminoglycans in primary cortical and cerebellar astrocytes in vitro.
- Author
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Martins RC, Lima FR, Werneck CC, Neto VM, and Silva LC
- Subjects
- Animals, Autoradiography, Cell Compartmentation, Cell Culture Techniques, Cerebellar Cortex cytology, Cerebellum cytology, Chondroitin Sulfates biosynthesis, Chondroitin Sulfates metabolism, Heparitin Sulfate biosynthesis, Heparitin Sulfate metabolism, Neuroglia metabolism, Rats, Sulfur Radioisotopes, Astrocytes metabolism, Glycosaminoglycans biosynthesis, Glycosaminoglycans metabolism
- Abstract
We determined the amounts of [35S]-glycosaminoglycans (GAGs) found on the intracellular, pericellular and extracellular compartments of primary cultures of astrocytes derived from newborn rat cortex and cerebellum in vitro. Our results show that the greatest portion of newly synthesized GAGs were found in different cellular compartments, depending on the source of the astrocytes. In the cells derived from the cerebellum, the proportion of [35S]-GAGs secreted to the culture medium preponderates over the amount found in the two other compartments, whereas cells derived from the cortex accumulated higher proportions of [35S]-GAGs in the intracellular compartment than in the two other compartments. Cortical and cerebellar glial cells synthesised and secreted heparan sulfate (HS) and chondroitin 4-sulfate (C-4S). HS was predominantly accumulated on the pericellular surface, while C-4S was mostly secreted to the culture medium. Beside the difference on the distribution of total [35S]-GAGs among the three cellular compartments, no difference was observed on the relative proportions of HS and C-4S within each compartment. By defining the source of GAGs, the present study may help to complement and extend information on biosynthesis of these compounds by mammalian glial cells.
- Published
- 2000
- Full Text
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36. Cerebellar astrocytes treated by thyroid hormone modulate neuronal proliferation.
- Author
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Gomes FC, Maia CG, de Menezes JR, and Neto VM
- Subjects
- Animals, Animals, Newborn, Astrocytes physiology, Cell Count, Cell Division drug effects, Cells, Cultured, Colforsin pharmacology, Culture Media, Conditioned pharmacology, Cyclic AMP physiology, Growth Inhibitors pharmacology, Nerve Growth Factors immunology, Nerve Growth Factors physiology, Rats, Rats, Wistar, Astrocytes drug effects, Cerebellum cytology, Neurons physiology, Triiodothyronine pharmacology
- Abstract
Thyroid hormones are important for neurogenesis and gliogenesis during brain development. We have previously demonstrated that triiodothyronine (T3) treatment induced proliferation in primary culture astrocytes derived from the cerebellum of neonatal rats. Conditioned medium obtained from those T3-treated astrocytes (T3CM) mimicked the effect of hormonal treatment on these cells. Because neuron-glia interaction plays an important role in brain development, we tested the ability of such T3-glial CM to influence neuronal physiology. With that aim, neurons from 19-day embryonic cerebella were cultivated for 24 h in the presence of CM obtained from T3-treated cerebellar astrocytes. Interestingly, the cerebellar neuronal population increased by 60-80% in T3CM. Addition of 5 microM forskolin enhanced the responsiveness of cerebellar neurons to astrocytes T3CM, but it did not interfere with neuronal survival in control medium. Conversely, inhibition of adenylate cyclase by its specific inhibitor, SQ22536, reversed the T3CM effect on neurons. These data strongly suggest that cAMP signal transduction pathways might be implicated in such an event. Analysis of bromodeoxyuridil incorporation revealed that the increase in neuron number in T3CM was partially due to neuron proliferation, because the proliferation index was three times higher in T3CM than in control medium. Neutralizing antibody assays demonstrated that T3CM effects on neurons are due, at least in part, to the presence of tumor necrosis factor-beta and epidermal growth factor. Thus, we report here a novel molecular mechanism of action of thyroid hormone on cerebellar neuronal cells: Thyroid hormone induces astrocytes to secrete growth factors that can interfere with neuronal proliferation via a paracrine pathway.
- Published
- 1999
37. Thyroid hormone acting on astrocytes in culture.
- Author
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Trentin AG, Gomes FC, Lima FR, and Neto VM
- Subjects
- Animals, Astrocytes cytology, Astrocytes metabolism, Cells, Cultured, Culture Media, Conditioned, Glial Fibrillary Acidic Protein metabolism, Rats, Astrocytes drug effects, Triiodothyronine pharmacology
- Published
- 1998
- Full Text
- View/download PDF
38. Complementary hydropathy identifies a cellular prion protein receptor.
- Author
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Martins VR, Graner E, Garcia-Abreu J, de Souza SJ, Mercadante AF, Veiga SS, Zanata SM, Neto VM, and Brentani RR
- Subjects
- Amino Acid Sequence, Animals, Antibodies immunology, Cells, Cultured, Genetic Techniques, Humans, Mice, Molecular Sequence Data, Neurons cytology, PrPC Proteins immunology, PrPC Proteins toxicity, Rats, Receptors, Cell Surface chemistry, Tumor Cells, Cultured, PrPC Proteins metabolism, Receptors, Cell Surface analysis, Receptors, Cell Surface metabolism
- Abstract
Prions, the etiological agents for infectious degenerative encephalopathies, act by entering the cell and inducing conformational changes in PrPC (a normal cell membrane sialoglycoprotein), which result in cell death. A specific cell-surface receptor to mediate PrPC and prion endocytosis has been predicted. Complementary hydropathy let us generate a hypothetical peptide mimicking the receptor binding site. Antibodies raised against this peptide stain the surface of mouse neurons and recognize a 66-kDa membrane protein that binds PrPC both in vitro and in vivo. Furthermore, both the complementary prion peptide and antiserum against it inhibit the toxicity of a prion-derived peptide toward neuronal cells in culture. Such reagents might therefore have therapeutic applications.
- Published
- 1997
- Full Text
- View/download PDF
39. Desmin filaments in the electrocytes of the electric organ of the electric eel Electrophorus electricus.
- Author
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Cordeiro MC, Benchimol M, Mermelstein CS, Sá LA, Faria MV, Chagas C, and Neto VM
- Subjects
- Actin Cytoskeleton ultrastructure, Animals, Antibody Specificity, Desmin immunology, Electric Organ cytology, Electric Organ ultrastructure, Immunohistochemistry, Microscopy, Immunoelectron, Actin Cytoskeleton chemistry, Desmin analysis, Electric Organ chemistry, Electrophorus physiology
- Abstract
Desmin protein is an abundant constituent of the intermediate filaments in the electrocytes of the electric organ of the electric eel Electrophorus electricus. Polyclonal antibodies were raised against purified desmin from the electric organ and used for immunolabeling of the protein in reconstituted filaments. In thick sections of the main electric organ that has been stained with fluorescein-labeled desmin-specific antibodies, light microscope revealed a diffuse meshwork of desmin filaments dispersed in the cytoplasm of electrocytes. In the region under the membrane, the immunostaining was slightly more intense than elsewhere. The meshwork of intermediate filaments composed of desmin was examined by electron microscopy of the main electric organ. Immuno-gold labeling demonstrated a widespread meshwork of desmin filaments in the cytoplasm and in close association with the plasma membrane. These observations suggest that intermediate filaments play a role in the maintenance of the morphology of electrocytes and, as an intracellular meshwork spanning the width of the cell, they may contribute to the organization of the intracellular compartments.
- Published
- 1996
- Full Text
- View/download PDF
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