23 research outputs found
USO DE PLACEBO EM PESQUISAS CLĂNICAS: REVISĂO BIBLIOGRĂFICA E ASPECTOS BIOĂTICOS
O placebo Ă© uma substĂąncia inerte, sem propriedades terapĂȘuticas efetivas. Seu uso em pesquisas clĂnicas tem sido eticamente criticado, sobretudo nas doenças com tratamento conhecido. Visando controlar o abuso dessa prĂĄtica pelos mĂ©dicos brasileiros, o Conselho Federal de Medicina editou a Resolução n. 1.885, de 23 de outubro de 2008, proibindo vĂnculo de qualquer natureza com pesquisas mĂ©dicas envolvendo seres humanos, que utilizem placebo em seus experimentos, quando houver tratamento eficaz e efetivo para a doença pesquisada. No mesmo ano, procedeu-se a revisĂŁo da Declaração de Helsinque, cujo teor sobre o uso do placebo gerou controvĂ©rsias e crĂticas Ă©ticas. O presente trabalho teve o objetivo de verificar se houve alteração no percentual de ensaios clĂnicos com uso de placebo no Brasil, antes e apĂłs 2008, e analisar outras caracterĂsticas gerais dos ensaios clĂnicos, como as doenças pesquisadas e seus principais patrocinadores. O estudo foi realizado na plataforma de registros internacionais ClinicalTrials.gov, pesquisando-se os ensaios clĂnicos com intervenção por droga, fase III, desenvolvidos no Brasil, com e sem uso de placebo, nos perĂodos de 2003 a 2007 e de 2009 a 2013. Os resultados mostraram que: ocorreu aumento importante no nĂșmero de ensaios nos perĂodos considerados, passando de 392 antes para 615 apĂłs 2008; foi expressivo o percentual de ensaios clĂnicos que utilizaram placebo no Brasil, de 43,5% (438/1.007) nos Ășltimos 10 anos; nĂŁo houve diferença estatĂstica, nos ensaios por todos os patrocinadores, entre as proporçÔes dos testes clĂnicos com e sem placebo quando comparados os perĂodos anterior (42,6%) e posterior (44,1%) a 2008 (p = 0,690); considerados os estudos apenas com patrocĂnio da indĂșstria farmacĂȘutica, a mesma proporção se manteve nos perĂodos anterior e posterior a 2008 (p = 0,944); ocorreu significativo aumento nos ensaios financiados por outros ĂłrgĂŁos (universidades, Instituto Nacional de SaĂșde/EUA e outros) no perĂodo apĂłs 2008 em relação aos anos anteriores, de 16,1 para 43,1% (p = 0,006); verificou-se que 86,8% dos ensaios com uso de placebo foram patrocinados pela indĂșstria farmacĂȘutica multinacional; particularmente, por sete big pharma, que financiaram 47% (206/438) dos estudos com placebo no Brasil; g) quanto Ă s doenças estudadas nos ensaios com placebo, as neoplasias foram as mais pesquisadas, com 23,1% dos 438 ensaios, seguidas pelas do aparelho circulatĂłrio (12,8%), as endĂłcrinas, nutricionais e metabĂłlicas (12,3%) e as autoimunes (11%). Conclui-se a ineficĂĄcia das normas Ă©ticas editadas em 2008 para os mĂ©dicos brasileiros que participaram dos ensaios clĂnicos nos perĂodos considerados, a grande presença da indĂșstria farmacĂȘutica multinacional nos patrocĂnios dos estudos realizados no Brasil e o predomĂnio das pesquisas de novos fĂĄrmacos para doenças crĂŽnicas.Palavras-chave: Ensaio clĂnico. Placebo. BioĂ©tica. IndĂșstria farmacĂȘutica. MĂ©dico
A functional network driven by microRNA-125a regulates monocyte trafficking in acute inflammation
During the onset of acute inflammation, rapid trafficking of leukocytes is essential to mount appropriate immune responses towards an inflammatory insult. Monocytes are especially indispensable for counteracting the inflammatory stimulus, neutralising the noxa and reconstituting tissue homeostasis. Thus, monocyte trafficking to the inflammatory sites needs to be precisely orchestrated. In this study, we identify a regulatory network driven by miR-125a that affects monocyte adhesion and chemotaxis by the direct targeting of two adhesion molecules, i.e., junction adhesion molecule A (JAM-A), junction adhesion molecule-like (JAM-L) and the chemotaxis-mediating chemokine receptor CCR2. By investigating monocytes isolated from patients undergoing cardiac surgery, we found that acute yet sterile inflammation reduces miR-125a levels, concomitantly enhancing the expression of JAM-A, JAM-L and CCR2. In contrast, TLR-4-specific stimulation with the pathogen-associated molecular pattern (PAMP) LPS, usually present within the perivascular inflamed area, resulted in dramatically induced levels of miR-125a with concomitant repression of JAM-A, JAM-L and CCR2 as early as 3.5 h. Our study identifies miR-125a as an important regulator of monocyte trafficking and shows that the phenotype of human monocytes is strongly influenced by this miRNA, depending on the type of inflammatory stimulus
Cell-crossing functional network driven by microRNA-125a regulates endothelial permeability and monocyte trafficking in acute inflammation
Opening of the endothelial barrier and targeted infiltration of leukocytes into the affected tissue are hallmarks of the inflammatory response. The molecular mechanisms regulating these processes are still widely elusive. In this study, we elucidate a novel regulatory network, in which miR-125a acts as a central hub that regulates and synchronizes both endothelial barrier permeability and monocyte migration. We found that inflammatory stimulation of endothelial cells induces miR-125a expression, which consecutively inhibits a regulatory network consisting of the two adhesion molecules VE-Cadherin (CDH5) and Claudin-5 (CLDN5), two regulatory tyrosine phosphatases (PTPN1, PPP1CA) and the transcription factor ETS1 eventually leading to the opening of the endothelial barrier. Moreover, under the influence of miR-125a, endothelial expression of the chemokine CCL2, the most predominant ligand for the monocytic chemokine receptor CCR2, was strongly enhanced. In monocytes, on the other hand, we detected markedly repressed expression levels of miR-125a upon inflammatory stimulation. This induced a forced expression of its direct target gene CCR2, entailing a strongly enhanced monocyte chemotaxis. Collectively, cell-type-specific differential expression of miR-125a forms a synergistic functional network controlling monocyte trafficking across the endothelial barrier towards the site of inflammation. In addition to the known mechanism of miRNAs being shuttled between cells via extracellular vesicles, our study uncovers a novel dimension of miRNA function: One miRNA, although disparately regulated in the cells involved, directs a biologic process in a synergistic and mutually reinforcing manner. These findings provide important new insights into the regulation of the inflammatory cascade and may be of great use for future clinical applications
El uso de placebo en ensayos clĂnicos de fase III en Brasil
In 2008, Brazilâs Federal Council of Medicine [Conselho Federal de Medicina] (CFM) â regulatory and supervisory agency on the ethical practice of medicine â banned the participation of Brazilian doctors in studies using placebos for diseases with efficient and effective treatment. This position differs with the Helsinki Declaration, which allows the use of placebos in methodologically justified conditions. To ascertain whether the CMFâs ethical regulation modified the use of placebos in phase III clinical trials in Brazil, characteristics of the records in ClinicalTrials.govwere researched in the periods from 2003 to 2007 and from 2009 to 2013. The conclusions reached were: a) the regulations issued by the CFM in 2008 were ineffective and the position adopted by the Helsinki Declaration prevails; b) there was significant sponsorship by the multinational pharmaceutical industry of trials with placebos; c) the research was predominantly on new drugs for chronic diseases, with little study done of the neglected diseases which are of great importance to Brazil.El Consejo Federal de Medicina de Brasil (CFM) âĂłrgano normativo y fiscalizador del ejercicio Ă©tico de la medicinaâ prohibiĂł, en 2008, la participaciĂłn de mĂ©dicos brasileños en investigaciones que utilizaran placebo para enfermedades con tratamiento eficaz y efectivo, en contraposiciĂłn a la DeclaraciĂłn de Helsinki, que permite su uso en condiciones metodolĂłgicamente justificadas. Con el objetivo de verificar si la normativa Ă©tica del CFM modificĂł el uso de placebo en ensayos clĂnicos de fase III en Brasil, se analizaron varias caracterĂsticas de sus registros en el ClinicalTrials.gov, en los perĂodos de 2003 a 2007 y de 2009 a 2013. Se concluye que: a) la normativa promulgada por el CFM en 2008 fue ineficaz y prevaleciĂł la posiciĂłn adoptada por la DeclaraciĂłn de Helsinki; b) el patrocinio de ensayos con placebo por parte de la industria farmacĂ©utica multinacional fue significativo; c) predominaron las investigaciones de fĂĄrmacos para enfermedades crĂłnicas, y fueron poco significativas para las enfermedades postergadas, de importancia para Brasil
Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19
IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19.
Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19.
DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 nonâcritically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022).
INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (nâ=â257), ARB (nâ=â248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; nâ=â10), or no RAS inhibitor (control; nâ=â264) for up to 10 days.
MAIN OUTCOMES AND MEASURES The primary outcome was organ supportâfree days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes.
RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ supportâfree days among critically ill patients was 10 (â1 to 16) in the ACE inhibitor group (nâ=â231), 8 (â1 to 17) in the ARB group (nâ=â217), and 12 (0 to 17) in the control group (nâ=â231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ supportâfree days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively).
CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes.
TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570
Homologation of Boronic Esters with Organolithium Compounds: A Computational Assessment of Mechanism
Ab initio calculations are reported for the
reaction of methyl boronic ester with organolithium reagents
with α-leaving groups. The best calculations rely on density
functional theory prediction of structures and coupled-cluster
theory calculation of accurate potential energies. The results
provide strong confirmation of the feasibility of a two-step
mechanism with rapid initial formation of a boronâate complex followed by slower migration of methyl from boron to carbon with loss of the leaving group. The calculated free energy of activation is consistent with observed kinetic behavior, and the calculations provide a framework for exploring substituent and other effects on reactivity. Obtaining reasonable agreement with experiment in this way is not trivial and requires careful treatment of level of theory (density functional theory calculations tend to yield inaccurate results), of conformational complexity, especially for the ate complexes, and of the nature of the microscopic model of reactants and solvent. The methodological challenges and possible pitfalls, many of which are relevant more broadly to computational modeling of organic reaction mechanisms, are discussed in detail.status: publishe
What is in a word? No versus Yes differentially engage the lateral orbitofrontal cortex.
Brain Insulin Resistance at the Crossroads of Metabolic and Cognitive Disorders in Humans
Mechanisms of MAFG Dysregulation in Cholestatic Liver Injury and Development of Liver Cancer
BACKGROUND & AIMS:MAF bZIP transcription factor G (MAFG) is activated by the farnesoid X receptor to repress bile acid synthesis. However, expression of MAFG increases during cholestatic liver injury in mice and in cholangiocarcinomas. MAFG interacts directly with methionine adenosyltransferase α1 (MATα1) and other transcription factors at the E-box element to repress transcription. We studied mechanisms of MAFG up-regulation in cholestatic tissues and the pathways by which S-adenosylmethionine (SAMe) and ursodeoxycholic acid (UDCA) prevent the increase in MAFG expression. We also investigated whether obeticholic acid (OCA), an farnesoid X receptor agonist, affects MAFG expression and how it contributes to tumor growth in mice. METHODS:We obtained 7 human cholangiocarcinoma specimens and adjacent non-tumor tissues from patients that underwent surgical resection in California and 113 hepatocellular carcinoma (HCC) specimens and adjacent non-tumor tissues from China, along with clinical data from patients. Tissues were analyzed by immunohistochemistry. MAT1A, MAT2A, c-MYC, and MAFG were overexpressed or knocked down with small interfering RNAs in MzChA-1, KMCH, Hep3B, and HepG2 cells; some cells were incubated with lithocholic acid (LCA, which causes the same changes in gene expression observed during chronic cholestatic liver injury in mice), SAMe, UDCA (100 ÎŒM), or farnesoid X receptor agonists. MAFG expression and promoter activity were measured using real-time polymerase chain reaction, immunoblot, and transient transfection. We performed electrophoretic mobility shift, and chromatin immunoprecipitation assays to study proteins that occupy promoter regions. We studied mice with bile-duct ligation, orthotopic cholangiocarcinomas, cholestasis-induced cholangiocarcinoma, diethylnitrosamine-induced liver tumors, and xenograft tumors. RESULTS:LCA activated expression of MAFG in HepG2 and MzChA-1 cells, which required the activator protein-1, nuclear factor-ÎșB, and E-box sites in the MAFG promoter. LCA reduced expression of MAT1A but increased expression of MAT2A in cells. Overexpression of MAT2A increased activity of the MAFG promoter, whereas knockdown of MAT2A reduced it. MAT1A and MAT2A had opposite effects on the activator protein-1, nuclear factor-ÎșB, and E-box-mediated promoter activity. Expression of MAFG and MAT2A increased, and expression of MAT1A decreased, in diethylnitrosamine-induced liver tumors in mice. SAMe and UDCA had shared and distinct mechanisms of preventing LCA-mediated increased expression of MAFG. OCA increased expression of MAFG, MAT2A, and c-MYC, but reduced expression of MAT1A. Incubation of human liver and biliary cancer cells lines with OCA promoted their proliferation; in nude mice given OCA, xenograft tumors were larger than in mice given vehicle. Levels of MAFG were increased in human HCC and cholangiocarcinoma tissues compared with non-tumor tissues. High levels of MAFG in HCC samples correlated with hepatitis B, vascular invasion, and shorter survival times of patients. CONCLUSIONS:Expression of MAFG increases in cells and tissues with cholestasis, as well as in human cholangiocarcinoma and HCC specimens; high expression levels correlate with tumor progression and reduced survival time. SAMe and UDCA reduce expression of MAFG in response to cholestasis, by shared and distinct mechanisms. OCA induces MAFG expression, cancer cell proliferation, and growth of xenograft tumors in mice