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Connexin hemichannels were identified as the first members of the eukaryotic large-pore channel family that mediate permeation of both atomic ions and small molecules between the intracellular and extracellular environments. The conventional view is that their pore is a large passive conduit through which both ions and molecules diffuse in a similar manner. In stark contrast to this notion, we demonstrate that the permeation of ions and of molecules in connexin hemichannels can be uncoupled and differentially regulated. We find that human connexin mutations that produce pathologies and were previously thought to be loss-of-function mutations due to the lack of ionic currents are still capable of mediating the passive transport of molecules with kinetics close to those of wild-type channels. This molecular transport displays saturability in the micromolar range, selectivity, and competitive inhibition, properties that are tuned by specific interactions between the permeating molecules and the N-terminal domain that lies within the pore-a general feature of large-pore channels. We propose that connexin hemichannels and, likely, other large-pore channels, are hybrid channel/transporter-like proteins that might switch between these two modes to promote selective ion conduction or autocrine/paracrine molecular signaling in health and disease processes.
Assuntos
Conexinas , Humanos , Conexinas/metabolismo , Conexinas/genética , Transporte de Íons , Animais , Mutação , Íons/metabolismo , Junções Comunicantes/metabolismo , Canais Iônicos/metabolismo , Canais Iônicos/genéticaRESUMO
In the context of ionic liquid (IL)-assisted catalysis, we have investigated the adsorption and thermal evolution of the IL 1,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide ([C1C1Im][Tf2N]) on Pt(111) between 100 and 800 K by angle-resolved X-ray photoelectron spectroscopy and scanning tunneling microscopy. Defined amounts of IL in the coverage range of a complete first wetting layer were deposited at low temperature (100-200 K), and subsequently heated to 300 K, or directly at 300 K. At 100 K, the IL adsorbs as an intact disordered layer. Upon heating to 200 K, the IL stays intact, but forms an ordered and well-oriented structure. Upon heating to 250 K, the surface order increases, but at the same time STM and XPS indicate the onset of decomposition. Upon heating to 300 K, decomposition progresses, such that 50-60% of the IL is decomposed. The anion-related reaction products desorb instantaneously, and the cation-related products remain on the surface. Thereby, the surface is partly passivated, enabling the remaining IL to still be adsorbed intact at 300 K. For IL deposition directly at 300 K, a fraction of the IL instantaneously decomposes, with the anion-related products desorbing, opening free space for further deposition of IL. Hence, cation-related species accumulate at the expense of anions, until one fully closed wetting layer is formed. As a consequence, a higher dose is required to reach this coverage at 300 K, compared to 100-200 K.
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Understanding the factors that control the demetalation of surface porphyrins at the solid-liquid interface is important as the molecular properties of porphyrins are largely determined by their metal centers. In this work, we used X-ray photoelectron spectroscopy (XPS) to follow the demetalation of Zn and Cd tetraphenylporphyrin molecules (ZnTPP and CdTPP) adsorbed as three-monolayer-thin multilayer films on Au(111), by exposing the molecular layers to acidic aqueous solutions. We found that porphyrin molecules at the solid-liquid interface are less prone to lose their metal center than molecules in solution. We propose that this behavior is due to either the incoming protons provided by the solution or the outgoing metal ion having to pass through the hydrophobic porphyrin multilayers where they cannot be solvated. Our results are relevant for the design of molecular devices based on porphyrin molecules adsorbed on solid surfaces.
RESUMO
Porphyrins are large organic molecules that are interesting for different applications, such as photovoltaic cells, gas sensors, or in catalysis. For many of these applications, the interactions between adsorbed molecules and surfaces play a crucial role. Studies of porphyrins on surfaces typically fall into one of two groups: (1) evaporation onto well-defined single-crystal surfaces under well-controlled ultrahigh vacuum conditions or (2) more application-oriented wet chemical deposition onto less well-defined high surface area surfaces under ambient conditions. In this study, we will investigate the wet chemical deposition of 5-(monocarboxyphenyl)-10,15,20-triphenylporphyrin (MCTPP) on well-defined rutile TiO2(110) single crystals under ambient conditions. Prior to deposition, the TiO2(110) crystals were also cleaned wet-chemically under ambient conditions, meaning none of the preparation steps were done in ultrahigh vacuum. However, after each preparation step, the surfaces were characterized in ultrahigh vacuum with X-ray photoelectron spectroscopy (XPS) and the result was compared with porphyrin layers prepared in ultrahigh vacuum (UHV) by evaporation. The differences of both preparations when exposed to zinc ion solutions will also be discussed.
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We have studied the adsorption and interfacial reactions of 2H-tetraphenylporphyrin (2HTPP) with cobalt-terminated Co3 O4 (111) and oxygen-terminated CoO(111) thin films using synchrotron-radiation X-ray photoelectron spectroscopy. Already at 275â K, we find evidence for the formation of a metalated species, most likely CoTPP, on both surfaces. The degree of self-metalation increases with temperature on both surfaces until 475â K, where the metalation is almost complete. At 575â K the porphyrin coverage decreases drastically on the reducible cobalt-terminated Co3 O4 (111) surface, while higher temperatures are needed on the non-reducible oxygen-terminated CoO(111). The low temperature self-metalation is similar to that observed on MgO(100) surfaces, but drastically different from that observed on TiO2 (110), where no self-metalation is observed at room temperature.
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The electronic structure of aromatic and aliphatic thiols on Au(111) has been extensively studied in relation to possible applications in molecular electronics. In this work, the effect on the electronic structure of an additional anchor to the S-Au bond using 6-mercaptopurine as a model system has been investigated. Results from X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, and density functional theory (DFT) confirm that this molecule adsorbs on Au(111) with S-Au and iminic N-Au bonds. Combined ultraviolet photoelectron spectroscopy and DFT data reveal that formation of the 6MP self-assembled monolayer generates a molecular dipole perpendicular to the surface, with negative charges residing at the metal/monolayer interface and positive charges at the monolayer/vacuum interface, which lowers the substrate work function. Scanning tunneling microscopy shows two surface molecular domains: a well-ordered rectangular lattice where molecules are tilted on average 30° with respect to the substrate and aligned 6MP islands where molecules are standing upright. Finally, we found a new electronic state located at -1.7 eV with respect to the Fermi level that corresponds to a localized π molecular state, while the state corresponding to the N-Au bond is hybridized with Au d electrons and stabilized at much lower energies (-3 eV).
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Two unusual occurrences of pleural trichomonosis due to a new Tetratrichomonas species previously reported but not named were confirmed. In one patient, Trichomonas tenax and a Tetratrichomonas species were also detected in the oral cavity by molecular methods. We suggest that this new Tetratrichomonas species be named Tetratrichomonas empyemagena.
Assuntos
Empiema Pleural/diagnóstico , Empiema Pleural/parasitologia , Infecções por Protozoários/diagnóstico , Infecções por Protozoários/parasitologia , Trichomonadida/classificação , Trichomonadida/isolamento & purificação , Adulto , Análise por Conglomerados , DNA Intergênico/química , DNA Intergênico/genética , DNA de Protozoário/química , DNA de Protozoário/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Humanos , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Boca/parasitologia , Filogenia , RNA Ribossômico 5,8S/genética , Análise de Sequência de DNA , Trichomonadida/genéticaRESUMO
INTRODUCTION: Oncologic patients can have severe infections due to Aeromonas. This study aims to investigate the clinical characteristics and outcomes of cancer patients with bloodstream infections (BSI) caused by Aeromonas. METHODOLOGY: We included patients with bacteremia caused by Aeromonas species from 2011 to 2018. RESULTS: Seventy-five BSI events in the same number of patients were identified. Forty patients were men (53.3%); the mean age was 49 years (IQR 28-61). A. caviae was the most frequent isolate (n = 29, 38.6%), followed by A. hydrophila (n = 23, 30.6%), A. sobria (n = 15, 20%), and A. veronii (n = 8, 10.6%). The most frequent underlying diagnosis was hematologic malignancy (n = 33, 44%), followed by breast cancer (n = 12, 16%) and gastrointestinal tract cancer (n = 8, 10.6%). The most frequent type of bacteremia was CRBSI in 32 cases (42.6%), followed by mucosal barrier injury-laboratory confirmed BSI (n = 20, 26.7%). Sixteen (26.2%) were hospital-acquired BSI. Attributable mortality occurred in 11 patients (14.6%). In univariate analysis A. hydrophila bacteremia, liver failure, skin/soft tissue infection, septic shock, inappropriate antimicrobial treatment, and relapse or cancer progression were associated with 30-day mortality. In multivariate analysis, only septic shock, inappropriate antimicrobial treatment, and relapse or cancer progression were associated with 30-day mortality. CONCLUSIONS: Aeromonas species should be considered one of the causative pathogens of healthcare-associated bacteremia, especially in immunocompromised patients. In addition, it can be associated with high fatality, particularly in patients with severe clinical infections.
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Aeromonas , Anti-Infecciosos , Bacteriemia , Infecções por Bactérias Gram-Negativas , Choque Séptico , Masculino , Humanos , Pessoa de Meia-Idade , Feminino , Recidiva Local de Neoplasia , Anti-Infecciosos/uso terapêutico , Bacteriemia/tratamento farmacológico , Bacteriemia/epidemiologia , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Infecções por Bactérias Gram-Negativas/epidemiologiaRESUMO
Cardiovascular diseases (CVDs) are the leading cause of mortality in Latin America and the Caribbean (LAC), with the risk in men being slightly higher than in women. The coronavirus disease 2019 (COVID-19) pandemic caused a significant reduction in the number of cardiac diagnostic procedures globally and in particular in LAC. Nuclear cardiology is available in the region, but there is variability in terms of existing technology, radiopharmaceuticals, and human resources. In the region, there are 2385 single photon emission computed tomography (SPECT) and 315 PET scanners, Argentina and Brazil have the largest number. There is an increasing number of new technologies such as cadmium-zinc-telluride (CZT) cardiac-dedicated gamma cameras, SPECT/computed tomography (CT), and PET/CT. All countries performed myocardial perfusion imaging studies, mainly gated-SPECT; the rest are multi-gated acquisition, mainly for cardiac toxicity; detection of viability; rest gated SPECT in patients with dilated cardiomyopathy, and bone-avid tracer cardiac scintigraphy for transthyretin cardiac amyloidosis diagnosis. Regarding other non-nuclear cardiac imaging modalities, Argentina, Colombia, and Chile have the highest ratio of CT scanners, while Brazil, Argentina, and Chile show the highest ratio of MRI scanners. The development of nuclear cardiology and other advanced imaging modalities is challenged by the high cost of equipment, lack of equipment maintenance and service, insufficient-specific training both for imaging specialists and referring clinicians, and lack of awareness of cardiologists or other referring physicians on the clinical applications of nuclear cardiology. Another important aspect to consider is the necessity of implementing cardiac imaging multimodality training. A joint work of nuclear medicine specialists, radiologists, cardiologists, and clinicians, in general, is mandatory to achieve this goal. National, regional, and international cooperation including support from scientific professional societies such as the American Society of Nuclear Cardiology and Latin American Association of Biology and Nuclear Medicine Societies, cardiological societies, and organizations such as the International Atomic Energy Agency, and Pan American Health Organization, as well as government commitment are key factors in the overall efforts to tackle the burden of cardiovascular diseases in the region.
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COVID-19 , Cardiologia , Doenças Cardiovasculares , Imagem de Perfusão do Miocárdio , Masculino , Humanos , Feminino , América Latina , Doenças Cardiovasculares/diagnóstico por imagem , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , COVID-19/diagnóstico por imagem , Tomografia Computadorizada de Emissão de Fóton Único/métodos , Região do CaribeRESUMO
We describe a method to study porous thin-films deposited onto rotating disc electrodes (RDE) applied to non-platinum group electrocatalyst obtained by pyrolysis of iron phthalocyanine and carbon, FePc/C. The electroactive area and porous properties of the thin film electrodes were obtained using electrochemical impedance spectroscopy under the framework of de Levie impedance model. The electrocatalytic activity of different electrodes was correlated to the total electroactive area (Ap) and the penetration ratio parameter through the film under ac current. The cylindrical pore model was extended to the RDE boundary conditions and derived in a Koutecky-Levich type expression that allowed to separate the effect of the electroactive area and structural properties. The resulting specific electrocatalytic activity of FePc/C heat treated at different temperatures was correlated to FePc surface concentration.
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BACKGROUND: Adherence to treatment in Parkinson's disease (PD) is compromised due to the need for multiple therapies, comorbidities related to aging, and the complexity of therapeutic schemes. In the present study, we aimed to explore adherence to treatment in groups of PD patients from six Latin-American (LA) countries and identify its associated demographic and clinical parameters. METHODS: A multicenter, cross-sectional, exploratory study was conducted from September 2016 to March 2017. Treatment adherence was assessed using the simplified medication adherence questionnaire (SMAQ), applied to patients and caregivers. Sociodemographic and clinical variables (MDS-UPDRS Part III-IV, MMSE, Beck Depression Inventory-II (BDI-II)) were recorded. RESULTS: Eight hundred patients from six LA countries were evaluated. Nonadherence was reported in 58.25% of the population, according to patients. The most frequent issues were forgetfulness and correct timing of doses. A high level of agreement in adherence prevalence and most SMAQ items were observed between patients and their caregivers. The nonadherent population had a significantly higher proportion of unemployment, free access to medication, troublesome dyskinesias and off-periods, lesser years of education, and worse motor, cognitive, and mood scores. In multiple logistic and linear regression analyses, MDS-UPDRS Part III, BDI-II, gender, free access to medication, treatment with dopamine agonists alone, years of education, excessive concerns about adverse effects, and beliefs about being well-treated remained significant contributors to adherence measures. CONCLUSION: Educational strategies, greater involvement of PD patients in decision-making, and consideration of their beliefs and values might be of great need to improve medication adherence in this PD population.
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Adesão à Medicação/estatística & dados numéricos , Doença de Parkinson/terapia , Idoso , Cuidadores , Comorbidade , Estudos Transversais , Escolaridade , Emprego , Feminino , Humanos , América Latina , Masculino , Adesão à Medicação/psicologia , Pessoa de Meia-Idade , Doença de Parkinson/psicologia , Análise de Regressão , Índice de Gravidade de Doença , Fatores Sociodemográficos , Inquéritos e QuestionáriosRESUMO
HIV infection is a major risk factor for tuberculosis. We describe the case of a 30-year-old male presenting with headache, compromised mental status, seizures, neck stiffness and fever that was subsequently diagnosed with HlV and neuroinfection. Clinical data, cerebrospinal fluid and brain imaging supported a diagnosis of neurotuberculosis. Cranial magnetic resonance imaging showed diffuse arachnoidal enhancement, mainly at the basal cisterns and cortical encephalitis. Such imaging findings play a key role in the diagnosis of central nervous system tuberculosis.
Assuntos
Aracnoidite/etiologia , Encefalite/etiologia , Soropositividade para HIV/complicações , Tuberculoma Intracraniano/etiologia , Adulto , Humanos , MasculinoAssuntos
Encefalopatias/etiologia , Encefalopatias/terapia , Cistos/etiologia , Estimulação Encefálica Profunda/efeitos adversos , Eletrodos Implantados/efeitos adversos , Complicações Pós-Operatórias , Encefalopatias/cirurgia , Cistos/diagnóstico por imagem , Cistos/cirurgia , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Doença de Parkinson/terapia , Técnicas EstereotáxicasRESUMO
A taxonomy of personality-relevant situations will provide a valuable complement to the taxonomy of personality attributes. To identify some of the most important modifying factors, we asked laypersons what modifies expression of their own traits. Spontaneously generated situation descriptors were elicited from 77 university students, leading to over 7,000 reports of situations. We determined the most frequently occurring words and phrases, and developed initial classification categories. Next, we tested the reliability of the categories, and made refinements to focus on those that proved most reliable. Based on results, we propose that situation descriptions involve at least four separable broad domains of variables--locations, associations, activities, and passively experienced processes--each of which appears to have distinct linguistic markers.
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Determinação da Personalidade/estatística & dados numéricos , Personalidade/classificação , Autoimagem , Comportamento Social , Meio Social , Adulto , California , Feminino , Humanos , Controle Interno-Externo , Relações Interpessoais , Masculino , Desenvolvimento da Personalidade , Psicometria , Enquadramento Psicológico , Estudantes/psicologiaRESUMO
La infección por VIH es uno de los mayores factores de riesgo para tuberculosis. Presentamos el caso de un paciente de 30 años que ingresó al hospital con datos neurológicos caracterizados por cefalea, alteración del alerta, crisis convulsivas, signos meníngeos y fiebre, a quien subsecuentemente se le diagnosticó VIH y neuroinfección. Los datos clínicos, el examen del líquido cefalorraquídeo y la neuroimagen sustentaron el diagnóstico de neurotuberculosis. La resonancia magnética de cráneo reveló aracnoiditis generalizada de predominio basal, así como encefalitis cortical. Los hallazgos de imagen desempeñan un papel fundamental en el diagnóstico integral de la tuberculosis del sistema nervioso central.
HIV infection is a major risk factor for tuberculosis. We describe the case of a 30-year-old male presenting with headache, compromised mental status, seizures, neck stiffness and fever that was subsequently diagnosed with HlV and neuroinfection. Clinical data, cerebrospinal fluid and brain imaging supported a diagnosis of neurotuberculosis. Cranial magnetic resonance imaging showed diffuse arachnoidal enhancement, mainly at the basal cisterns and cortical encephalitis. Such imaging findings play a key role in the diagnosis of central nervous system tuberculosis.