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BACKGROUND: Article summaries' information and structure may influence researchers/clinicians' decisions to conduct deeper full-text analyses. Specifically, abstracts of systematic reviews (SRs) and meta-analyses (MA) should provide structured summaries for quick assessment. This study explored a method for determining the methodological quality and bias risk of full-text reviews using abstract information alone. METHODS: Systematic literature searches for SRs and/or MA about psoriasis were undertaken on MEDLINE, EMBASE, and Cochrane database. For each review, quality, abstract-reporting completeness, full-text methodological quality, and bias risk were evaluated using Preferred Reporting Items for Systematic Reviews and Meta-analyses for abstracts (PRISMA-A), Assessing the Methodological Quality of Systematic Reviews (AMSTAR), and ROBIS tools, respectively. Article-, author-, and journal-derived metadata were systematically extracted from eligible studies using a piloted template, and explanatory variables concerning abstract-reporting quality were assessed using univariate and multivariate-regression models. Two classification models concerning SRs' methodological quality and bias risk were developed based on per-item and total PRISMA-A scores and decision-tree algorithms. This work was supported, in part, by project ICI1400136 (JR). No funding was received from any pharmaceutical company. RESULTS: This study analysed 139 SRs on psoriasis interventions. On average, they featured 56.7% of PRISMA-A items. The mean total PRISMA-A score was significantly higher for high-methodological-quality SRs than for moderate- and low-methodological-quality reviews. SRs with low-bias risk showed higher total PRISMA-A values than reviews with high-bias risk. In the final model, only 'authors per review > 6' (OR: 1.098; 95%CI: 1.012-1.194), 'academic source of funding' (OR: 3.630; 95%CI: 1.788-7.542), and 'PRISMA-endorsed journal' (OR: 4.370; 95%CI: 1.785-10.98) predicted PRISMA-A variability. Reviews with a total PRISMA-A score < 6, lacking identification as SR or MA in the title, and lacking explanation concerning bias risk assessment methods were classified as low-methodological quality. Abstracts with a total PRISMA-A score ≥ 9, including main outcomes results and explanation bias risk assessment method were classified as having low-bias risk. CONCLUSIONS: The methodological quality and bias risk of SRs may be determined by abstract's quality and completeness analyses. Our proposal aimed to facilitate synthesis of evidence evaluation by clinical professionals lacking methodological skills. External validation is necessary.
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Indexação e Redação de Resumos/normas , Publicações Periódicas como Assunto/normas , Psoríase/terapia , Literatura de Revisão como Assunto , Viés , Humanos , Metanálise como Assunto , Psoríase/diagnóstico , Editoração/normas , Controle de Qualidade , Projetos de Pesquisa/normas , Relatório de Pesquisa/normas , Fatores de RiscoRESUMO
Background: Microglial dysfunction plays a causative role in Alzheimer's disease (AD) pathogenesis. Here we focus on a germline insertion/deletion variant mapping SIRPß1, a surface receptor that triggers amyloid-ß(Aß) phagocytosis via TYROBP. Objective: To analyze the impact of this copy-number variant in SIRPß1 expression and how it affects AD molecular etiology. Methods: Copy-number variant proxy rs2209313 was evaluated in GERALD and GR@ACE longitudinal series. Hippocampal specimens of genotyped AD patients were also examined. SIRPß1 isoform-specific phagocytosis assays were performed in HEK393T cells. Results: The insertion alters the SIRPß1 protein isoform landscape compromising its ability to bind oligomeric Aß and its affinity for TYROBP. SIRPß1 Dup/Dup patients with mild cognitive impairment show an increased cerebrospinal fluid t-Tau/Aß ratio (pâ=â0.018) and a higher risk to develop AD (ORâ=â1.678, pâ=â0.018). MRIs showed that Dup/Dup patients exhibited a worse initial response to AD. At the moment of diagnosis, all patients showed equivalent Mini-Mental State Examination scores. However, AD patients with the duplication had less hippocampal degeneration (pâ<â0.001) and fewer white matter hyperintensities. In contrast, longitudinal studies indicate that patients bearing the duplication allele show a slower cognitive decline (pâ=â0.013). Transcriptional analysis also shows that the SIRPß1 duplication allele correlates with higher TREM2 expression and an increased microglial activation. Conclusions: The SIRPß1 internal duplication has opposite effects over MCI-to-Dementia conversion risk and AD progression, affecting microglial response to Aß. Given the pharmacological approaches focused on the TREM2-TYROBP axis, we believe that SIRPß1 structural variant might be considered as a potential modulator of this causative pathway.
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Doença de Alzheimer , Disfunção Cognitiva , Receptores de Superfície Celular , Humanos , Doença de Alzheimer/diagnóstico por imagem , Doença de Alzheimer/genética , Peptídeos beta-Amiloides/metabolismo , Disfunção Cognitiva/diagnóstico por imagem , Disfunção Cognitiva/genética , Disfunção Cognitiva/metabolismo , Microglia/metabolismo , Fagocitose , Receptores de Superfície Celular/metabolismoRESUMO
Alzheimer's disease is the most common cause of dementia worldwide, and longitudinal studies are crucial to find the factors affecting disease development. Here, we describe a novel initiative from southern Spain designed to contribute in the identification of the genetic component of the cognitive decline of Alzheimer's disease patients. The germline variant rs9320913 is a C>A substitution mapping within a gene desert. Although it has been previously associated to a higher educational achievement and increased fluid intelligence, its role on Alzheimer's disease risk and progression remains elusive. A total of 407 subjects were included in the study, comprising 153 Alzheimer disease patients and 254 healthy controls. We have explored the rs9320913 contribution to both Alzheimer disease risk and progression according to the Mini-Mental State Exams. We found that rs9320913 maps within a central nervous system lincRNA AL589740.1. eQTL results show that rs9320913 correlated with the brain-frontal cortex (beta = -0.15, p value = 0.057) and brain-spinal cord (beta of -0.23, p value = 0.037). We did not find rs9320913 to be associated to AD risk, although AA patients seemed to exhibit a less pronounced Mini-Mental State Exam score decline.
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INTRODUCTION: The Janus kinase and Signal Transducer and Activator of Transcription protein (JAK/STAT) pathway is known to be involved in inflammatory and neoplastic skin diseases, like psoriasis, atopic dermatitis, alopecia areata, vitiligo and melanoma. Improved knowledge of the components of this pathway has allowed the development of drugs, which act by inhibiting the pathway, blocking specific components. This offers new therapeutic opportunities. Although evidence on the use of JAK/STAT blockades in dermatological diseases is growing, none have been approved for use in treating skin diseases. The aim of this study is to develop an a priori protocol to broadly review the available evidence on the use of drugs targeting the JAK/STAT pathway in the treatment of dermatological diseases. METHODS AND ANALYSIS: For the conduction of the scoping review protocol, we will employ an established scoping review methodology described in the Joanna Briggs Institute manual. This methodology outlines a five-stage approach: (1) identify the research question; (2) identify relevant studies; (3) select studies; (4) chart the data and (5) collate, summarise and report the results, with an optional consultation exercise. Finally, we will use the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews to present the results. ETHICS AND DISSEMINATION: Since this is a review of the literature, ethics approval is not indicated. We will disseminate the findings from this study in publications in peer-reviewed journals as well as presentations at relevant national and international conferences.
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Inibidores de Janus Quinases/uso terapêutico , Dermatopatias/tratamento farmacológico , Humanos , Janus Quinases/imunologia , Nitrilas , Piperidinas/uso terapêutico , Pirazóis/uso terapêutico , Pirimidinas/uso terapêutico , Pirróis/uso terapêutico , Fatores de Transcrição STAT/imunologia , Dermatopatias/imunologiaRESUMO
This research-on-research study describes efforts to develop non-Cochrane systematic reviews (SRs) by analyzing demographical and time-course collaborations between international institutions using protocols registered in the International Prospective Register of Systematic Reviews (PROSPERO) or published in scientific journals. We have published an a priori protocol to develop this study. Protocols published in scientific journals were searched using the MEDLINE and Embase databases; the query terms "Systematic review" [Title] AND "protocol" [Title] were searched from February 2011 to December 2017. Protocols registered at PROSPERO during the same period were obtained by web scraping all non-Cochrane records with a Python script. After excluding protocols that had a fulfillment or duplication rate of less than 90%, they were classified as published "only in PROSPERO", "only in journals", or in "journals and PROSPERO". Results of data and metadata extraction using text mining processes were curated by two reviewers. These Datasets and R scripts are freely available to facilitate reproducibility. We obtained 20,814 protocols of non-Cochrane SRs. While "unique protocols" by reviewers' institutions from 60 countries were the most frequent, a median of 6 (2-150) institutions from 130 different countries were involved in the preparation of "collaborative protocols". The highest Ranked countries involved in overall protocol production were the UK, the U.S., Australia, Brazil, China, Canada, the Netherlands, Germany, and Italy. Most protocols were registered only in PROSPERO. However, the number of protocols published in scientific journals (924) or in both PROSPERO and journals (807) has increased over the last three years. Syst Rev and BMJ Open published more than half of the total protocols. While the more productive countries were involved in "unique" and "collaborative protocols", less productive countries only participated in "collaborative protocols" that were mainly published in PROSPERO. Our results suggest that, although most countries were involved in solitary production of protocols for non-Cochrane SRs during the study period, it would be useful to develop new strategies to promote international collaborations, especially with less productive countries.
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Mineração de Dados , Metadados , PubMed , Revisões Sistemáticas como Assunto , Humanos , Publicações Periódicas como AssuntoRESUMO
INTRODUCTION: The interleukin (IL)-1 pathway has been identified as being involved in inflammatory and neoplastic skin diseases such as psoriasis, atopic dermatitis, neutrophilic dermatosis, melanoma, and squamous cell carcinoma. Drugs developed to target the IL-1 pathway are currently used to treat these pathologies, and although they are becoming more selective, they are not exempt from adverse events and high costs. Integrating the best research evidence with clinical experience and patient needs has been shown to improve care, health, and cost outcomes. This is because evidence-based guidelines rank interventions according to cost-effectiveness. However, evidence on this topic is scarce for several reasons. First, although randomized clinical trials currently provide the best evidence, they are not always available. Second, there are no secondary scientific studies that summarize the use of IL-1-targeting agents in dermatology. We therefore sought to develop an a priori protocol for broadly reviewing the available evidence on the use of IL-1-targeting drugs in the treatment of dermatological diseases. METHODS: We used the latest methodology to perform a scoping review as described in the Joanna Briggs Institute manual. RESULTS/DISCUSSION: Developing and applying a methodology for evidence synthesis promotes reproducibility and increases the validity of secondary scientific investigations, making it the optimal strategy for scientifically synthesizing a broad field such as the indications for and the mechanisms of action, efficacies, safety, and costs of IL-1-targeting drugs in the treatment of dermatological diseases. Quantitative synthesis facilitates the detection of knowledge gaps and the identification of new questions that can be addressed through systematic reviews. We present an a priori protocol for exploring the available evidence on this topic.
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Researchers are increasingly using on line social networks to promote their work. Some authors have suggested that measuring social media activity can predict the impact of a primary study (i.e., whether or not an article will be highly cited). However, the influence of variables such as scientific quality, research disclosures, and journal characteristics on systematic reviews and meta-analyses has not yet been assessed. The present study aims to describe the effect of complex interactions between bibliometric factors and social media activity on the impact of systematic reviews and meta-analyses about psoriasis (PROSPERO 2016: CRD42016053181). Methodological quality was assessed using the Assessing the Methodological Quality of Systematic Reviews (AMSTAR) tool. Altmetrics, which consider Twitter, Facebook, and Google+ mention counts as well as Mendeley and SCOPUS readers, and corresponding article citation counts from Google Scholar were obtained for each article. Metadata and journal-related bibliometric indices were also obtained. One-hundred and sixty-four reviews with available altmetrics information were included in the final multifactorial analysis, which showed that social media and impact factor have less effect than Mendeley and SCOPUS readers on the number of cites that appear in Google Scholar. Although a journal's impact factor predicted the number of tweets (OR, 1.202; 95% CI, 1.087-1.049), the years of publication and the number of Mendeley readers predicted the number of citations in Google Scholar (OR, 1.033; 95% CI, 1.018-1.329). Finally, methodological quality was related neither with bibliometric influence nor social media activity for systematic reviews. In conclusion, there seems to be a lack of connectivity between scientific quality, social media activity, and article usage, thus predicting scientific success based on these variables may be inappropriate in the particular case of systematic reviews.
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Bibliometria , Psoríase , Mídias Sociais , HumanosRESUMO
BACKGROUND: Epidemiology and the reporting characteristics of systematic reviews (SRs) and meta-analyses (MAs) are well known. However, no study has analyzed the influence of protocol features on the probability that a study's results will be finally reported, thereby indirectly assessing the reporting bias of International Prospective Register of Systematic Reviews (PROSPERO) registration records. OBJECTIVE: The objective of this study is to explore which factors are associated with a higher probability that results derived from a non-Cochrane PROSPERO registration record for a systematic review will be finally reported as an original article in a scientific journal. METHODS/DESIGN: The PROSPERO repository will be web scraped to automatically and iteratively obtain all completed non-Cochrane registration records stored from February 2011 to December 2017. Downloaded records will be screened, and those with less than 90% fulfilled or are duplicated (i.e., those sharing titles and reviewers) will be excluded. Manual and human-supervised automatic methods will be used for data extraction, depending on the data source (fields of PROSPERO registration records, bibliometric databases, etc.). Records will be classified into published, discontinued, and abandoned review subgroups. All articles derived from published reviews will be obtained through multiple parallel searches using the full protocol "title" and/or "list reviewers" in MEDLINE/PubMed databases and Google Scholar. Reviewer, author, article, and journal metadata will be obtained using different sources. R and Python programming and analysis languages will be used to describe the datasets; perform text mining, machine learning, and deep learning analyses; and visualize the data. We will report the study according to the recommendations for meta-epidemiological studies adapted from the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement for SRs and MAs. DISCUSSION: This meta-epidemiological study will explore, for the first time, characteristics of PROSPERO records that may be associated with the publication of a completed systematic review. The evidence may help to improve review workflow performance in terms of research topic selection, decision-making regarding team selection, planning relationships with funding sources, implementing literature search strategies, and efficient data extraction and analysis. We expect to make our results, datasets, and R and Python code scripts publicly available during the third quarter of 2018.
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Estudos Epidemiológicos , Metanálise como Assunto , Editoração/normas , Revisões Sistemáticas como Assunto , Humanos , Publicações Periódicas como Assunto/normasRESUMO
AIMS: Experimental autoimmune encephalomyelitis (EAE) is considered a valid experimental model for multiple sclerosis, a chronic neuroinflammatory condition of the central nervous system. Additionally, some evidence has shown that some microbial products such as the bacterial lipopolysaccharide could lead to the activation of reactive immune cells, triggering neuroinflammation. Several studies have found that transcranial magnetic stimulation (TMS) may exert a neuroprotective effect. Therefore, we aimed to assess the effect of TMS on the neuroinflammation occurring in EAE. MATERIALS AND METHODS: A total of 44 male Dark Agouti rats were used. EAE induction was performed administering subcutaneously at the dorsal base of the tail a single dose of myelin oligodendrocyte glycoprotein. Clinical evaluation of motor symptoms was performed. Brain and spinal cord were collected and analyzed for nitric oxide, bacterial lipopolysaccharide and lipopolysaccharide-binding protein. We also carried out a histologic exam, which included an astrocyte immunostaining and Nissl staining for the assessment of brain cell density and pyknotic nuclei. KEY FINDINGS: TMS effectively ameliorated motor impairment secondary to EAE. This form of magnetic field was capable of decreasing the proliferation of astrocytes as a response to the autoimmune attack, reducing the content of nitric oxide, bacterial lipopolysaccharide and lipopolysaccharide-binding protein in central nervous system. Moreover, in treated animals, brain cell density was improved and the number of pyknotic nuclei was decreased. SIGNIFICANCE: Transcranial magnetic stimulation modifies astrocytosis, cell density and lipopolysaccharide levels in EAE. These results suggest that TMS could be a promising treatment for neuroinflammatory conditions such as multiple sclerosis.
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Astrócitos/patologia , Encéfalo/patologia , Encefalomielite Autoimune Experimental/patologia , Encefalomielite Autoimune Experimental/terapia , Lipopolissacarídeos/análise , Estimulação Magnética Transcraniana , Proteínas de Fase Aguda/análise , Animais , Proteínas de Transporte/análise , Contagem de Células , Modelos Animais de Doenças , Masculino , Glicoproteínas de Membrana/análise , Óxido Nítrico/análise , RatosRESUMO
Experimental autoimmune encephalomyelitis (EAE) reproduces a multiple sclerosis (MS)-like experimental model. The main objective was to evaluate the effect of extremely low-frequency electromagnetic fields (EL-EMF) application, like a paradigm of transcranial magnetic stimulation (TMS) in the development of EAE. Rats were injected with a single dose of 150 µg of myelin oligodendrocyte glycoprotein (MOG, fragment 35-55) to produce experimental MS. To assess the effect of TMS application in EAE, the rats were treated with TMS (60 Hz and 0.7 mT) for 2 h in the morning, once a day, 5 days a week, during 3 weeks. TMS was applied to the head. The effect of TMS on EAE was evaluated as motor symptoms and, oxidative and cell damage. The data showed that MOG induced motor symptoms as tail paralysis and limb paresis/paralysis, oxidative stress and cell death similar to MS when compared with control animals. Importantly, TMS application attenuated motor symptoms, oxidative and cell damage, whereas it increased antioxidant system. Our findings suggest that: (i) MOG reproduces an experimental model of MS characterised by oxidative and cell damage; and (ii) TMS application decreases oxidative stress and cell death induced by MOG.
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Encefalomielite Autoimune Experimental/metabolismo , Estresse Oxidativo , Estimulação Magnética Transcraniana , Animais , Apoptose , Encéfalo/enzimologia , Encéfalo/patologia , Encefalomielite Autoimune Experimental/terapia , Glutationa/metabolismo , L-Lactato Desidrogenase/metabolismo , Masculino , Mitocôndrias/metabolismo , Esclerose Múltipla/metabolismo , Esclerose Múltipla/terapia , RatosRESUMO
Recent findings in experimental autoimmune encephalomyelitis (EAE) suggest that altering certain bacterial populations present in the gut may lead to a proinflammatory condition, that could result in the development of multiple sclerosis (MS). Also, Reactive Oxygen Species seem to be involved in the course of MS. In this study, it has been aimed to relate all these variables starting from an analysis of the lipopolysaccharide (LPS) and LPS-binding protein (LBP) with the determination of parameters related to oxidative stress in the blood, brain and spinal cord. For this purpose, samples obtained from EAE rats and relapsing-remitting (RRMS) MS patients were used. In addition, EAE rats were treated with Natalizumab, N-acetyl-cysteine and dimethyl fumarate. Natalizumab was also employed in RRMS. The results of this study revealed an improvement in the clinical symptoms of the EAE and MS with the treatments, as well as a reduction in the oxidative stress parameters and in LBP. Correlations between the clinical variables of the disease, i.e. oxidative damage and LBP, were established. Although the conclusions of this research are indeed relevant, further investigation would be necessary to establish the intrinsic mechanisms of the MS-oxidative stress-microbiota relationship.
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Proteínas de Fase Aguda/metabolismo , Proteínas de Transporte/metabolismo , Glicoproteínas de Membrana/metabolismo , Esclerose Múltipla/metabolismo , Estresse Oxidativo , Acetilcisteína/administração & dosagem , Adulto , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Contagem de Células , Dasyproctidae , Fumarato de Dimetilo/administração & dosagem , Encefalomielite Autoimune Experimental/metabolismo , Feminino , Humanos , Peroxidação de Lipídeos , Lipopolissacarídeos/metabolismo , Masculino , Pessoa de Meia-Idade , Natalizumab/administração & dosagem , Neurônios/efeitos dos fármacos , Ratos , Medula Espinal/efeitos dos fármacos , Medula Espinal/metabolismoRESUMO
Moderate-to-severe psoriasis is associated with significant comorbidity, an impaired quality of life, and increased medical costs, including those associated with treatments. Systematic reviews (SRs) and meta-analyses (MAs) of randomized clinical trials are considered two of the best approaches to the summarization of high-quality evidence. However, methodological bias can reduce the validity of conclusions from these types of studies and subsequently impair the quality of decision making. As co-authorship is among the most well-documented forms of research collaboration, the present study aimed to explore whether authors' collaboration methods might influence the methodological quality of SRs and MAs of psoriasis. Methodological quality was assessed by two raters who extracted information from full articles. After calculating total and per-item Assessment of Multiple Systematic Reviews (AMSTAR) scores, reviews were classified as low (0-4), medium (5-8), or high (9-11) quality. Article metadata and journal-related bibliometric indices were also obtained. A total of 741 authors from 520 different institutions and 32 countries published 220 reviews that were classified as high (17.2%), moderate (55%), or low (27.7%) methodological quality. The high methodological quality subnetwork was larger but had a lower connection density than the low and moderate methodological quality subnetworks; specifically, the former contained relatively fewer nodes (authors and reviews), reviews by authors, and collaborators per author. Furthermore, the high methodological quality subnetwork was highly compartmentalized, with several modules representing few poorly interconnected communities. In conclusion, structural differences in author-paper affiliation network may influence the methodological quality of SRs and MAs on psoriasis. As the author-paper affiliation network structure affects study quality in this research field, authors who maintain an appropriate balance between scientific quality and productivity are more likely to develop higher quality reviews.
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Autoria , Confiabilidade dos Dados , Metanálise como Assunto , Psoríase/terapia , Literatura de Revisão como Assunto , Viés , Bibliometria , HumanosRESUMO
OBJECTIVES: No gold standard exists to assess methodological quality of systematic reviews (SRs). Although Assessing the Methodological Quality of Systematic Reviews (AMSTAR) is widely accepted for analyzing quality, the ROBIS instrument has recently been developed. This study aimed to compare the capacity of both instruments to capture the quality of SRs concerning psoriasis interventions. STUDY DESIGN AND SETTING: Systematic literature searches were undertaken on relevant databases. For each review, methodological quality and bias risk were evaluated using the AMSTAR and ROBIS tools. Descriptive and principal component analyses were conducted to describe similarities and discrepancies between both assessment tools. RESULTS: We classified 139 intervention SRs as displaying high/moderate/low methodological quality and as high/low risk of bias. A high risk of bias was detected for most SRs classified as displaying high or moderate methodological quality by AMSTAR. When comparing ROBIS result profiles, responses to domain 4 signaling questions showed the greatest differences between bias risk assessments, whereas domain 2 items showed the least. CONCLUSION: When considering SRs published about psoriasis, methodological quality remains suboptimal, and the risk of bias is elevated, even for SRs exhibiting high methodological quality. Furthermore, the AMSTAR and ROBIS tools may be considered as complementary when conducting quality assessment of SRs.
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Psoríase/epidemiologia , Psoríase/terapia , Literatura de Revisão como Assunto , Viés de Seleção , Estudos Epidemiológicos , Feminino , Humanos , Masculino , Psoríase/diagnóstico , Controle de Qualidade , EspanhaRESUMO
AIMS: The main aim of this study was to verify the effect of natalizumab on the levels of circulating catecholamines and indolamine and their possible relation with MS. METHODS: For this purpose, 12 healthy individuals (control group) and 12 relapsing-remitting multiple sclerosis patients (RR-MS) were selected. The patients were treated with 300 mg of natalizumab during 56 weeks (1 dose/4 weeks) (MS-56). This selection was based on the McDonalds revision criterion and scheduled to star treatment with natalizumab. Blood samples were taken before treatment (basal level) and after 56 weeks of using natalizumab. Melatonin was measured in serum and in plasma, catecholamines (dopamine, epinephrine, and norepinephrine), carbonylated proteins, 8-hydroxy-2'deoxyguanosine (8OH-dG) and the ratio reduced glutathione/oxidised glutathione (GSH/GSSG). RESULTS: The epinephrine and dopamine levels diminished in the basal group with respect to the control and did not recover normal levels with the treatment. The melatonin was decreased in RR-MS patients and went back to its normal levels with natalizumab. Norepinephrine was increased in RR-MS and decreased in MS-56 until it equalled the control group. CONCLUSION: Natalizumab normalizes altered melatonin and norepinephrine levels in MS.
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Catecolaminas/sangue , Esclerose Múltipla Recidivante-Remitente/sangue , Esclerose Múltipla Recidivante-Remitente/tratamento farmacológico , Natalizumab/uso terapêutico , Adulto , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Esclerose Múltipla Recidivante-Remitente/patologia , Natalizumab/administração & dosagemRESUMO
INTRODUCTION: Skeletal muscle is a target organ in multiple sclerosis, a chronic debilitating disease of the central nervous system caused by demyelination and axonal deterioration. Since the experimental autoimmune encephalomyelitis model reproduces the relapsing-remitting course found in most multiple sclerosis patients, this model was used to compare the histological features of skeletal muscle at onset with those observed at the start of the second relapse. MATERIAL AND METHODS: Histological, histochemical and ultrastructural changes, as well as biochemical oxidative damage and antioxidant-system markers, were examined in the soleus and extensor digitorum longus muscles of Dark Agouti rats in which experimental autoimmune encephalomyelitis had been induced by active immunization using myelin oligodendrocyte glycoprotein. RESULTS: Histological examination at disease onset revealed ragged-red fibers and ultrastructural evidence of mitochondrial degeneration. At the second relapse, neurogenic changes included a wide range of cytoarchitectural lesions, skeletal muscle atrophy and the appearance of intermediate fibers; however, differences were observed between soleus and extensor digitorum longus lesions. Biochemical tests disclosed an increase in oxidative stress markers at onset, which was more pronounced at the second relapse. CONCLUSIONS: Microscopic findings suggest that two patterns can be distinguished at disease onset: an initial phase characterized by muscle mitochondrial alterations, and a second phase dominated by a histological muscle pattern of clearly neurogenic origin.