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Purines are ubiquitous structures in cell biology involved in a multitude of cellular processes, because of which substituted purines and analogs are considered excellent scaffolds in drug design. In this study, we explored the key structural features of a purine-based proapoptotic hit, 8-tert-butyl-9-phenyl-6-benzyloxy-9H-purine (1), by setting up a library of 6-alkoxy purines with the aim of elucidating the structural requirements that govern its biological activity and to study the cell selectivity of this chemotype. This was done by a phenotypic screening approach based on cell cycle analysis of a panel of six human cancer cell lines, including T cell leukemia Jurkat cells. From this study, two derivatives (12 and 13) were identified as Jurkat-selective proapoptotic compounds, displaying superior potency and cell selectivity than hit 1.
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Antineoplásicos/farmacologia , Leucemia de Células T/tratamento farmacológico , Purinas/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Humanos , Células Jurkat , Leucemia de Células T/patologia , Purinas/síntese química , Purinas/química , Relação Estrutura-AtividadeRESUMO
Lateral flow assays may be used by minimally trained personnel for fast and inexpensive bioanalyses in decentralized non-exigent environments. Their extension to a broader catalog of applications depends on improvements in their quantification and their sensitivity. We report a strategy that combines nanomagnetic tagging of the analyte of interest with radiofrequency inductive sensing, easy to achieve in friendly and portable format. To optimize nanotag performance, we investigated the influences of their magnetic core size and agglomeration. Iron oxide nanoparticles, with sizes from 5 to 23 nm, were synthesized by thermal decomposition and then coated with dimercaptosuccinic acid and functionalized with neutravidin protein. We tested the system by immobilizing biotin in lateral flow membrane strips. When a sample containing the particles flows along the membrane, the biotin captures the neutravidin together with the magnetic nanotags, which are detected by the inductive sensor. The optimal nanotag core size is the critical threshold for superparamagnetic behavior, which maximizes both the initial magnetic permeability and the saturation magnetization. Controlled agglomeration of the nanotags increases the magnetic mass captured in the test line and further amplifies the signal.
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Histamine, a biogenic amine, is abundant in fermented foods and beverages, notably wine. A high intake of this monoamine may produce adverse reactions in humans, which may be severe in individuals with a reduced capacity to catabolise extrinsic histamine. Thus, control of histamine concentration during wine production and before distribution is advisable. Simple, rapid, point-of-use bioanalytical platforms are needed because traditional methods for the detection and quantification of histamine are expensive and time-consuming. This work applies the lateral flow immunoassay technique to histamine detection. Superparamagnetic particle labels, and an inductive sensor designed to read the test line in the immunoassay, enable magnetic quantification of the molecule. The system is calibrated with histamine standards in the interval of interest for wine production. A commercial optical strip reader is used for comparison measurements. The lateral flow system has a limit of detection of 1.2 and 1.5 mg/L for the inductive and optical readers, respectively. The capability of the inductive system for histamine quantification is demonstrated for wine samples at different processing points (at the end of alcoholic fermentation, at the end of malolactic fermentation, in freshly bottled wine, and in reserve wine). The results are validated by ultra-high-performance liquid chromatography. Graphical abstract.
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Histamina/análise , Vinho/análise , Aminas Biogênicas/análise , Desenho de Equipamento , Imunoensaio/métodos , Limite de Detecção , Nanopartículas de Magnetita/química , Fitas Reagentes/análiseRESUMO
BACKGROUND: Chronic musculoskeletal pain affects more than 20% of the population, and the prevalence is increasing, causing suffering, loss of quality of life, disability, and an enormous expenditure on healthcare resources. The most common location for chronic pain is the spine. Many of the treatments used are mainly passive (pharmacological and invasive) and poor outcomes. The treatments currently applied in the public health system do not comply with the recommendations of the main clinical practice guidelines, which suggest the use of educational measures and physical exercise as the first-line treatment. A protocol based on active coping strategies is described, which will be evaluated through a clinical trial and which could facilitate the transfer of the recommendations of the clinical practice guidelines to a primary care setting. METHODS: Randomised and multicentre clinical trials, which will be carried out in 10 Primary Care centres. The trial will compare the effect of a Pain Neuroscience Education program (six sessions, 10 h) and group physical exercise (18 sessions program carried out in six weeks, 18 h), with usual care physiotherapy treatment. Group physical exercise incorporates dual tasks, gaming, and reinforcement of contents of the educational program. The aim is to assess the effect of the intervention on quality of life, as well as on pain, disability, catastrophism, kinesiophobia, central sensitisation, and drug use. The outcome variables will be measured at the beginning of the intervention, after the intervention (week 11), at six months, and a year. DISCUSSION: Therapeutic interventions based on active coping strategies are essential for the treatment of chronic pain and the sustainability of the Public Health System. Demonstrating whether group interventions have an effect size is essential for optimising resources in such a prevalent problem. TRIAL REGISTRATION: NCT03654235 "Retrospectively registered" 31 August 2018.
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Dor Crônica/terapia , Terapia por Exercício/métodos , Exercício Físico/fisiologia , Educação de Pacientes como Assunto/métodos , Atenção Primária à Saúde/métodos , Doenças da Coluna Vertebral/terapia , Adaptação Psicológica/fisiologia , Adulto , Idoso , Dor Crônica/diagnóstico , Dor Crônica/psicologia , Exercício Físico/psicologia , Humanos , Pessoa de Meia-Idade , Doenças da Coluna Vertebral/diagnóstico , Doenças da Coluna Vertebral/psicologia , Adulto JovemRESUMO
This paper describes the development of simple, sustainable, and low-cost strategies for signal enhancement on paper-based carbon platforms through gold nanoparticles electrogenerated from small volumes of tetrachloroauric (III) acid solutions. Carbon ink is deposited on a hydrophilic working area of the paper delimited with hydrophobic wax. This maskless procedure is fast and cuts down ink waste. The connection of this working electrode to the potentiostat is ensured with the use of screen-printed electrodes (SPEs). Close contact of the whole area of both carbon electrodes improves the precision of the nanostructuration. Resulting gold-modified paper-based carbon working electrodes (AuNPs-PCWEs) were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and electron dispersion X-ray spectrometry (SEM/EDX). This methodology was applied for the first time to the inorganic arsenic determination in commercial white wines by chronoamperometric stripping of the electrodeposited As(0). In an optimized system, As(III) was reduced and deposited as As(0) on the nanostructured surface by applying a potential of -0.3 V during 180 s. Then, anodic stripping chronoamperometry was performed at +0.4 V. The analytical signal was the current recorded at 30 s. On the other hand, As(V) was chemically reduced to As(III) with 0.2 M KI, and total determination of arsenic could be carried out. As(V) was determined as the difference between total As and As(III). Then, this fast, simple and low-cost method can be employed for speciation purposes. Limits of detection for As(III) and total arsenic (in the presence of KI) are 2.2 µg L-1 and 2.4 µg L-1, respectively, and indicate that this method is suitable for regulated quality control.
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Arsênio/análise , Carbono/química , Ouro/química , Nanopartículas Metálicas/química , Papel , Vinho/análise , Espectroscopia Dielétrica , Técnicas Eletroquímicas , Eletrodos , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Porosidade , Propriedades de SuperfícieRESUMO
The emergence of antibiotic-resistant pathogens, multiple drug-resistance, and extremely drug-resistant strains demonstrates the need for improved strategies to discover new drug-based compounds. The development of transcriptomics, proteomics, and metabolomics has provided new tools for global studies of living organisms. However, the compendium of expression profiles produced by these methods has introduced new scientific challenges into antimicrobial research. In this review, we discuss the practical value of transcriptomic techniques as well as their difficulties and pitfalls. We advocate the construction of new databases of transcriptomic data, using standardized formats in addition to standardized models of bacterial and yeast similar to those used in systems biology. The inclusion of proteomic and metabolomic data is also essential, as the resulting networks can provide a landscape to rationally predict and exploit new drug targets and to understand drug synergies.
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Antibacterianos , Sistemas de Liberação de Medicamentos , Perfilação da Expressão Gênica , Bactérias/efeitos dos fármacos , Bactérias/genética , Bactérias/metabolismo , Farmacorresistência Bacteriana , Fungos/efeitos dos fármacos , Fungos/genética , Fungos/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Análise de Sequência de RNARESUMO
This study describes the prevalence, phenomenology, treatment, and outcome of neurological patients and psychiatric patients with catatonia at a tertiary neurological center. Clinical variables included nosological diagnoses and complications. Admission length and days with catatonia were used as outcome measures. Of 2,044 patients who were evaluated prospectively, 68 (3.32%) had catatonia, 42 (61.7%) were neurological patients, 19 (27.9%) were psychiatric patients, and 7 (10.2%) had drug-related diagnoses. Of all patients, the ratio of neurological to psychiatric patients was 3:1. Encephalitis was the most common diagnosis (N=26 [38.2%]), followed by schizophrenia (N=12 [17.6%]). Psychiatric patients exhibited a stuporous type of catatonia (15 [83.3%] versus 14 [33.3%], p>0.001), whereas neurological patients exhibited a mixed form of catatonia (25 [59.5%] versus 1 [5.6], p<0.001). Neurological patients had more complications, longer hospitalizations, and more days with catatonia. A total of 56 patients (82.3%) received lorazepam, and 14 patients (20.5%) underwent ECT. Second- and third-line treatments included amantadine, bromocriptine, and levodopa. Catatonia is a prevalent syndrome that can remit with proper and opportune treatment.
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Catatonia/epidemiologia , Encefalite/epidemiologia , Esquizofrenia/epidemiologia , Adolescente , Adulto , Catatonia/diagnóstico , Catatonia/terapia , Comorbidade , Encefalite/terapia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Esquizofrenia/terapia , Adulto JovemRESUMO
Vanillin is a natural compound easily extracted from plants. It has neuroprotective, anti-carcinogenic, antioxidant, antimicrobial, and anti-biofilm properties. It also presents high volatility, high hydrophilicity, and low bioavailability. Nanomaterials can be used to improve pharmacodynamics, solubility, and stability and to enhance pharmacokinetics. In this work, non-ionic surfactant vesicles were synthesized as vanillin carriers: neutral niosomes formed by Span60 and cholesterol, positive charged niosomes formulated with cetyltrimethylammonium bromide (CTAB), and negatively charged niosomes formulated with sodium dodecyl sulfate (SDS). Niosomes synthesis was carried out with two commonly used methods: thin film hydration (TFH) and ethanol injection method (EIM). The niosomes synthesized were used to prepare two different materials: (i) a powder containing the lyophilized noisome with vanillin systems and (ii) a gelatin matrix film containing niosomes with vanillin. Lyophilization was carried out using maltodextrin as a cryoprotectant. The lyophilization of colloidal structures allows for storage at room temperature for long periods of time, keeping their organoleptic characteristics invariable. Niosomes were characterized before and after the lyophilization process in terms of morphological characterization, size, polydispersity index (PDI), and zeta potential. Moreover, niosomes cargo was evaluated by calculating the encapsulation efficiency (EE) and loading capacity (LC). Results showed that the use of the TFH method allowed us to obtain niosomes of 255 nm with high EE (up to 40%) and LC values higher than EIM. The lyophilization process decreased the LC of the vesicles prepared, but this decrease was mitigated by up to 20% when ionic surfactants were used on the membrane bilayer. Gelatin films are biodegradable materials suitable for food packing applications. The incorporation of a natural compound with antimicrobial activity would be a clear advantage for such an application. The films prepared were characterized in terms of morphology, water solubility, color, and transparency. Niosomes synthesized by thin film hydration had better chemical and physical properties to load vanillin. Especially in the case of application in films, niosomes with a negative charge, formed by SDS, and vanillin loaded gave better mechanical and chemical characteristics to the film.
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The Theory of Planned Behavior (TPB) is one of the main theoretical models in the study of the different variables, which influence in the practise of physical activity. The aim in this study was to develop a questionnaire based on TPB in physical activity context providing evidence for the validity of the obtained measures. The instrumental project included three independent studies. The first study entailed the construction and qualitative assessment of the items. In the second study, the analysis of factorial structure was performed by means of exploratory measures, and it showed that the reliability of measures was adequate. The third study provided evidence on the dimensionality of the scale. The confirmatory factorial analysis guaranteed the stability of factorial structure proposed by the TPB and provided evidence for the internal validity of the inventory. Moreover, this study provided evidence of its external validity.
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Exercício Físico/psicologia , Comportamentos Relacionados com a Saúde , Intenção , Adulto , Análise Fatorial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Psicometria/instrumentação , Reprodutibilidade dos Testes , Inquéritos e QuestionáriosRESUMO
Splanchnic vein thrombosis is an unusual manifestation of venous thromboembolism and includes portal vein thrombosis, mesenteric veins thrombosis, splenic vein thrombosis, and the Budd-Chiari syndrome. The most common risk factors include hematologic and autoimmune disorders, hormonal therapy, liver cirrhosis, solid abdominal cancer, recent abdominal surgery, and abdominal infections or inflammatory conditions, such as pancreatitis. Splanchnic vein thrombosis in acute pancreatitis is most commonly associated with the severe form of the disease and pancreatic necrosis. This report describes a case of splanchnic vein thrombosis as a complication of necrotizing acute pancreatitis in a pediatric patient. Splanchnic vein thrombosis was incidentally detected on contrast-enhanced computed tomography to assess the pancreas. There was no evidence of prior risk factors for the thrombotic condition. The patient was treated with anticoagulation and showed complete resolution after recovery from necrotizing acute pancreatitis, at a 16-month follow-up. The complication of necrotizing acute pancreatitis with splanchnic vein thrombosis in pediatric age is a rare presentation.
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Olive oil is a key component of the highly cardiovascular protective Mediterranean diet. (-)-Oleocanthal (OLC) is one of the most interesting phenolics present in virgin olive oil, and is formed from secoiridoid ligustroside during the processing of olives to yield the oil. Anti-inflammatory and anti-oxidant properties were identified shortly after OLC isolation, followed by the discovery of anti-tumor activities in a few non-hematopoietic cell lineages. Because of the scarcity of tissues potentially targeted by OLC analyzed so far and the unresolved mechanism(s) for OLC anti-tumor properties, we used a panel of 17 cell lines belonging to 11 tissue lineages to carry out a detailed examination of targets and pathways leading to cell growth inhibition and death. We found that OLC inhibits cell proliferation and induces apoptotic death as revealed by sub-G1 cell cycle analyses and Annexin-V staining in all lineages analyzed except lung carcinoma cell lines. Hematopoietic tumor cell lines, untested until now, were the most sensitive to OLC treatment, whereas non-transformed cells were significantly resistant to cell death. The specificity of OLC-mediated caspase activation was confirmed by blocking experiments and the use of transfectants overexpressing anti apoptotic genes. OLC triggers typical mediators of the intrinsic apoptotic pathway such as production of reactive oxygen species and mitochondrial membrane depolarization (Δψm). Complete blockade of caspases, however, did not result in parallel abrogation of Annexin-V staining, thus suggesting that complex mechanisms are involved in triggering OLC-mediated cell death. Our results demonstrate that OLC preferentially targets hematopoietic tumor cell lines and support that cell death is mediated by caspase-dependent and independent mechanisms.
Assuntos
Caspases , Neoplasias Hematológicas , Humanos , Caspases/metabolismo , Monoterpenos Ciclopentânicos , Azeite de Oliva/análise , Apoptose , Espécies Reativas de Oxigênio/metabolismo , Linhagem Celular Tumoral , Anexinas , Caspase 3/metabolismoRESUMO
The present study estimates the prevalence of some enteropathogens in infants and preschoolers with acute diarrhea. From 2006 to 2007, 5459 consecutive stool samples were evaluated. Cryptosporidium parvum was the parasite identified with the higher frequency (5.1%), followed by Giardia lamblia (1.2%). Campylobacter jejuni was isolated in 858 cases (15.7%) and was the most frequent enteropathogen overall. The rates of C parvum, Shigella, and Salmonella were higher in the summer. Rotavirus had the expected winter peak and it was the third enteropathogen because of its frequency. Overall frequency of stool-reducing substances was 15.6% and was associated with a rotavirus-positive test.
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Infecções Bacterianas/epidemiologia , Diarreia/parasitologia , Enteropatias Parasitárias/epidemiologia , Estações do Ano , Doença Aguda , Criança , Pré-Escolar , Estudos Transversais , Diarreia/epidemiologia , Diarreia Infantil/epidemiologia , Diarreia Infantil/parasitologia , Fezes/microbiologia , Fezes/parasitologia , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , México/epidemiologia , PrevalênciaRESUMO
A new generation of magnetic lateral flow immunoassays is emerging as powerful tool for diagnostics. They rely on the use of magnetic nanoparticles (MNP) as detecting label, replacing conventional gold or latex beads. MNPs can be sensed and quantified by means of external devices, allowing the development of immunochromatographic tests with a quantitative capability. Moreover, they have an added advantage because they can be used for immunomagnetic separation (IMS), with improvements in selectivity and sensitivity. In this paper, we have reviewed the current knowledge on magnetic-lateral flow immunoassay (LFIA), coupled with both research and commercially available instruments. The work in the literature has been classified in two categories: optical and magnetic sensing. We have analysed the type of magnetic nanoparticles used in each case, their size, coating, crystal structure and the functional groups for their conjugation with biomolecules. We have also taken into account the analytical characteristics and the type of transduction. Magnetic LFIA have been used for the determination of biomarkers, pathogens, toxins, allergens and drugs. Nanocomposites have been developed as alternative to MNP with the purpose of sensitivity enhancement. Moreover, IMS in combination with other detection principles could also improve sensitivity and limit of detection. The critical analysis in this review could have an impact for the future development of magnetic LFIA in fields requiring both rapid separation and quantification.
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Superparamagnetic iron oxide nanoflowers coated by a black carbon layer (Fe3O4@C) were studied as labels in lateral flow immunoassays. They were synthesized by a one-pot solvothermal route, and they were characterized (size, morphology, chemical composition, and magnetic properties). They consist of several superparamagnetic cores embedded in a carbon coating holding carboxylic groups adequate for bioconjugation. Their multi-core structure is especially efficient for magnetic separation while keeping suitable magnetic properties and appropriate size for immunoassay reporters. Their functionality was tested with a model system based on the biotin-neutravidin interaction. For this, the nanoparticles were conjugated to neutravidin using the carbodiimide chemistry, and the lateral flow immunoassay was carried out with a biotin test line. Quantification was achieved with both an inductive magnetic sensor and a reflectance reader. In order to further investigate the quantifying capacity of the Fe3O4@C nanoflowers, the magnetic lateral flow immunoassay was tested as a detection system for extracellular vesicles (EVs), a novel source of biomarkers with interest for liquid biopsy. A clear correlation between the extracellular vesicle concentration and the signal proved the potential of the nanoflowers as quantifying labels. The limit of detection in a rapid test for EVs was lower than the values reported before for other magnetic nanoparticle labels in the working range 0-3 × 107 EVs/µL. The method showed a reproducibility (RSD) of 3% (n = 3). The lateral flow immunoassay (LFIA) rapid test developed in this work yielded to satisfactory results for EVs quantification by using a precipitation kit and also directly in plasma samples. Besides, these Fe3O4@C nanoparticles are easy to concentrate by means of a magnet, and this feature makes them promising candidates to further reduce the limit of detection.
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Técnicas Biossensoriais , Imunoensaio/métodos , Carbono , Limite de Detecção , Nanopartículas Magnéticas de Óxido de Ferro , Nanopartículas Metálicas , Reprodutibilidade dos TestesRESUMO
A different alternative to previous research on Langmuir and Langmuir-Blodgett (LB) films of bent-core liquid crystals is reported in this work. A bent-shaped molecule wearing a terminal carboxylic group has been used to obtain monomolecular films with their long molecular axis almost perpendicular to the aqueous surface. Langmuir films at the air-liquid interface (pH=9) have been characterized by a combination of surface pressure and surface potential versus area per molecule isotherms, Brewster angle microscopy, and ultraviolet reflection spectroscopy. A condensed phase is reached at surface pressures up to 20 mN x m-1. In this condensed phase, molecules are packed forming H-aggregates with a well-defined molecular orientation. Langmuir films have been transferred onto quartz and silicon substrates and characterized by means of UV-vis spectroscopy and XRR. The transference is Z-type, with a constant deposition of the monolayers. The total LB monolayer film thickness is evaluated to be about 5.8 nm, which is in good agreement with the deduced orientation at the air-liquid interface as well as with the lamellar order observed within the solid obtained by cooling the sample from the mesophase.
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Rpb5, a subunit shared by the three yeast RNA polymerases, combines a eukaryotic N-terminal module with a globular C-end conserved in all non-bacterial enzymes. Conditional and lethal mutants of the moderately conserved eukaryotic module showed that its large N-terminal helix and a short motif at the end of the module are critical in vivo. Lethal or conditional mutants of the C-terminal globe altered the binding of Rpb5 to Rpb1-beta25/26 (prolonging the Bridge helix) and Rpb1-alpha44/47 (ahead of the Switch 1 loop and binding Rpb5 in a two-hybrid assay). The large intervening segment of Rpb1 is held across the DNA Cleft by Rpb9, consistent with the synergy observed for rpb5 mutants and rpb9Delta or its RNA polymerase I rpa12Delta counterpart. Rpb1-beta25/26, Rpb1-alpha44/45 and the Switch 1 loop were only found in Rpb5-containing polymerases, but the Bridge and Rpb1-alpha46/47 helix bundle were universally conserved. We conclude that the main function of the dual Rpb5-Rpb1 binding and the Rpb9-Rpb1 interaction is to hold the Bridge helix, the Rpb1-alpha44/47 helix bundle and the Switch 1 loop into a closely packed DNA-binding fold around the transcription bubble, in an organization shared by the two other nuclear RNA polymerases and by the archaeal and viral enzymes.
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RNA Polimerases Dirigidas por DNA/química , Proteínas de Saccharomyces cerevisiae/química , Sequência de Aminoácidos , Núcleo Celular/enzimologia , Sequência Conservada , RNA Polimerases Dirigidas por DNA/genética , RNA Polimerases Dirigidas por DNA/metabolismo , Teste de Complementação Genética , Humanos , Modelos Moleculares , Dados de Sequência Molecular , Mutação , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Subunidades Proteicas/química , Subunidades Proteicas/genética , Subunidades Proteicas/metabolismo , RNA Polimerase II/química , RNA Polimerase II/metabolismo , Saccharomyces cerevisiae/enzimologia , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismoRESUMO
Extracellular vesicles (EV) are small membrane structures released by cells that act as potent mediators of intercellular communication. The study of EV biology is important, not only to strengthen our knowledge of their physiological roles, but also to better understand their involvement in several diseases. In the field of biomedicine they have been studied as a novel source of biomarkers and drug delivery vehicles. The most commonly used method for EV enrichment in crude pellet involves serial centrifugation and ultracentrifugation. Recently, different protocols and techniques have been developed to isolate EV that imply less time and greater purification. Here we carry out a comparative analysis of three methods to enrich EV from plasma of healthy controls: ultracentrifugation, ExoQuickTM precipitation solution (System Biosciences), and Total Exosome Isolation kit (Invitrogen). Our results show that commercial precipitation reagents are more efficient and enable higher EV enrichment factors compared with traditional ultracentrifugation, although subsequent imaging analysis is not possible with some of them. We hope that this work will contribute to the current research on isolation techniques to assist the progress of clinical applications with diagnostic or therapeutic objectives.
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The effect of applied pressure on the magnetic properties of the Prussian blue analogue K0.4Fe4[Cr(CN)6]2.8 x 16 H2O (1) has been analyzed by dc and ac magnetic susceptibility measurements. Under ambient conditions, 1 orders ferromagnetically at a critical temperature (T(C)) of 18.5 K. Under application of pressure in the 0-1200 MPa range, the magnetization of the material decreases and its critical temperature shifts to lower temperatures, reaching T(C) = 7.5 K at 1200 MPa. Pressure-dependent Raman and Mossbauer spectroscopy measurements show that this striking behavior is due to the isomerization of some Cr(III)-C[triple bond]N-Fe(II) linkages to the Cr(III)-N[triple bond]C-Fe(II) form. As a result, the ligand field around the iron(II) centers increases, and the diamagnetic low-spin state is populated. As the number of diamagnetic centers in the cubic lattice increases, the net magnetization and critical temperature of the material decrease considerably. The phenomenon is reversible: releasing the pressure restores the magnetic properties of the original material. However, we have found that under more severe pressure conditions, a metastable sample containing 22% Cr(III)-N[triple bond]C-Fe(II) linkages can be obtained. X-ray absorption spectroscopy and magnetic circular dichroism of this metastable sample confirm the linkage isomerization process.
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Compostos de Cromo/química , Cianetos/química , Compostos de Ferro/química , Magnetismo , Pressão , Água/química , Raios X , Cristalização , Isomerismo , Análise Espectral , Temperatura , Difração de Raios XRESUMO
Extra-virgin olive oil (OO) is becoming more important in daily diets due to its beneficial effects on health, most of which are because of its antioxidant content. We studied the antioxidant activity and mechanisms of an extra-virgin OO that is rich in phenolics on pancreatic islets and liver in control mice (CTL) fed a nonpurified diet and in mice supplemented with 50 microL/d sunflower oil (SO) or 50 microL/d extra-virgin OO for 4 d. Plasma hydroxytyrosol concentration was determined by HPLC-diode array detector. Plasma antioxidant capacity, enzymatic activities, and lipid peroxidation were measured by spectrophotometry. Islet function was studied by measuring insulin release. Islet cell gene expression was examined using quantitative RT-PCR. The plasma hydroxytyrosol concentration was greater in OO mice than in CTL or SO mice (P < 0.05) and was greater in SO mice than in CTL mice. The ratio of reduced:oxidized glutathione and the antioxidant capacity in plasma was greater in OO mice than in CTL or SO mice (P < 0.05) and higher in SO mice than in CTL mice. Glucose-stimulated insulin secretion was greater in OO mice than in CTL or SO mice (P < 0.05) and was also higher in SO mice than in CTL mice. Protection against liver cell and beta cell membrane lipid peroxidation was greater in OO mice than in CTL or SO mice (P < 0.05) and was greater in SO mice than in CTL mice. Catalase (CAT) expression in the islet of Langerhans was higher in OO mice than in CTL mice and SO mice (P < 0.05). The CAT and glutathione peroxidase 1 activities in the islet of Langerhans were 25% greater in OO mice than in CTL mice and higher than in SO mice (P < 0.05) and they were greater in SO mice than in CTL mice. These results indicate that, in metabolic tissues, protection by extra-virgin OO against oxidative stress occurs primarily through a direct antioxidant effect as well as through an indirect mechanism that involves greater expression and activity of certain enzymes with antioxidant activities.
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Antioxidantes/química , Antioxidantes/farmacologia , Óleos de Plantas/química , Óleos de Plantas/farmacologia , Animais , Membrana Celular/efeitos dos fármacos , Dieta , Suplementos Nutricionais , Peróxido de Hidrogênio/farmacologia , Peroxidação de Lipídeos , Fígado/efeitos dos fármacos , Masculino , Malondialdeído/metabolismo , Camundongos , Camundongos Endogâmicos , Azeite de Oliva , Óleo de GirassolRESUMO
The syntheses, structures, and magnetic properties of the compounds of formula [Fe (III)(sal 2trien)] 2[Mn (II) 2(ox) 3].4H 2O.C 3H 7NO ( 1) and [In (III)(sal 2trien)] 2[Mn (II) 2(ox) 3].3H 2O.CH 3OH (2) are reported. The structure presents a homometallic 2D honeycomb anionic layer formed by Mn (II) ions linked through oxalate ligands and a cationic double layer of [Fe(sal 2trien)] (+) or [In(sal 2trien)] (+) complexes intercalated between the 2D oxalate network. The magnetic properties and Mössbauer spectroscopy of 1 indicate the coexistence of a magnetic ordering of the Mn(II) oxalate network that behaves as a weak ferromagnet and a gradual spin crossover of the intercalated [Fe(sal 2trien)] (+) complexes.