RESUMO
OBJECTIVE: For many years, outcomes such as mortality and morbidity were the standard for evaluating oncological treatment effectiveness. With the introduction of patient-reported outcome measures (PROMs), the focus shifted from a mere extension of a patient's life or release from disease to the improvement of a multilayered concept of health, decisively affecting life satisfaction. In this study, we deal with the topic of PROMs in liver and gastrointestinal randomized controlled trials. RESULTS: The final database included 43 papers reporting results of randomized controlled trials (RCTs) for liver or gastrointestinal cancer interventions where one of the primary or secondary outcomes was a health-related quality of life measure. The most often used PROM was the European Organization for Research and Treatment of Cancer Quality of Life questionnaire (EORTC QLQ-C30) for both liver cancer and gastrointestinal cancer (in 62% of gastrointestinal cancer studies and 57% of liver cancer studies). For the gastrointestinal cancer group, the QLQ-STO22, a cancer-specific extension of the QLQ-C30, was the second most commonly used PROM. In liver cancer, the generic PROM Short Form 36 and the EORTC QLQ-HCC18, a cancer-specific extension of the QLQ-C30, were the second most commonly used PROMs. CONCLUSION: We found that RCTs often do not include comprehensive quality-of-life measures. When quality of life is part of an RCT, it is often only a secondary outcome. For a holistic view of the patient, a stronger integration and weighting of patient-reported outcomes in RCTs would be desirable.
Assuntos
Neoplasias Gastrointestinais , Neoplasias Hepáticas , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto , Neoplasias Hepáticas/terapia , Qualidade de Vida , Neoplasias Gastrointestinais/terapia , Medidas de Resultados Relatados pelo Paciente , Inquéritos e QuestionáriosRESUMO
The first microfluidic microphysiological systems (MPS) entered the academic scene more than 15 years ago and were considered an enabling technology to human (patho)biology in vitro and, therefore, provide alternative approaches to laboratory animals in pharmaceutical drug development and academic research. Nowadays, the field generates more than a thousand scientific publications per year. Despite the MPS hype in academia and by platform providers, which says this technology is about to reshape the entire in vitro culture landscape in basic and applied research, MPS approaches have neither been widely adopted by the pharmaceutical industry yet nor reached regulated drug authorization processes at all. Here, 46 leading experts from all stakeholders - academia, MPS supplier industry, pharmaceutical and consumer products industries, and leading regulatory agencies - worldwide have analyzed existing challenges and hurdles along the MPS-based assay life cycle in a second workshop of this kind in June 2019. They identified that the level of qualification of MPS-based assays for a given context of use and a communication gap between stakeholders are the major challenges for industrial adoption by end-users. Finally, a regulatory acceptance dilemma exists against that background. This t4 report elaborates on these findings in detail and summarizes solutions how to overcome the roadblocks. It provides recommendations and a roadmap towards regulatory accepted MPS-based models and assays for patients' benefit and further laboratory animal reduction in drug development. Finally, experts highlighted the potential of MPS-based human disease models to feedback into laboratory animal replacement in basic life science research.
Assuntos
Alternativas aos Testes com Animais , Bem-Estar do Animal , Desenvolvimento de Medicamentos , Avaliação Pré-Clínica de Medicamentos/métodos , Dispositivos Lab-On-A-Chip , Animais , Indústria Farmacêutica , Humanos , Modelos BiológicosRESUMO
Selenium is of special interest in different research fields due to its narrow range between beneficial and toxic effects. On a global scale, Se deficiency is more widespread. Biofortification measures have successfully been applied to specifically increase Se concentrations in food crops. Still not much is known about the behaviour and long-term fate of externally supplied Se. Over many years, natural but external selenate is regularly introduced into the soil-plant system via irrigation at our study sites in Punjab which makes it also an ideal natural analogue to investigate the long term effect of biofortification. For our study, we combined total and species specific analysis of Se in soil and plant material. Selenium is clearly enriched in all investigated topsoils (0-15 cm) with concentrations of 1.5-13.0 mg kg-1 despite similar background Se concentrations (0.5 ± 0.1 mg kg-1) below 15 cm depth. Irrigation is indicated to be the primary source of excess Se. Processes like Se species transformation, uptake by plants and plant material decomposition further influence both the Se speciation and extent of Se enrichment in the soils. The Se concentration in different plants and plant parts is alarmingly high showing concentrations of up to 738 mg kg-1 in wheat. Irrigation induced selenate can be considered as an easily available short term pool of Se for plants and thus strongly controls their total Se concentration and speciation. The long-term pool of Se in the topsoil mainly consists of selenite and organic Se species. These species are readily retained but still sufficiently mobile to be taken up by plants. The formation of elemental Se can be considered as a non-available Se pool and is thus, the major cause of Se immobilization and long-term enrichment of Se in the soils. Our study clearly shows that biofortification with selenate, despite its effectiveness, bears the risk of easily increasing Se levels in plants to toxic levels and producing food with less favourable inorganic Se species if not done with care. Excess selenate is either lost due to biomethylation or immobilized within the soil which has to be considered as highly negative from both an economic and ecological point of few.
Assuntos
Irrigação Agrícola , Água Subterrânea/análise , Plantas/química , Selênio/análise , Poluentes do Solo/análise , Poluentes Químicos da Água/análise , Monitoramento Ambiental , Índia , Ácido Selênico/análiseRESUMO
Selenium plays an important, but vastly neglected role in human nutrition with a narrow gap between dietary deficiency and toxicity. For a potential biofortification of food with Se, as well as for toxicity-risk assessment in sites contaminated by Se, modelling of local and global Se cycling is essential. As bioavailability of Se for rice plants depends on the speciation of Se and the resulting interactions with mineral surfaces as well as the interaction with Se uptake mechanisms in plants, resulting plant Se content is complex to model. Unfortunately, simple experimental models to estimate Se uptake into plants from substrates have been lacking. Therefore, a mass balance of Se transfer between lithosphere (represented by kaolinite), hydrosphere (represented by a controlled nutrient solution), and biosphere (represented by rice plants) has been established. In a controlled, closed, lab-scale system, rice plants were grown hydroponically in nutrient solution supplemented with 0-10 000 µg L-1 Se of either selenate or selenite. Furthermore, in a series of batch experiments, adsorption and desorption were studied for selenate and selenite in competition with each of the major nutrient oxy-anions, nitrate, sulfate and phosphate. In a third step, the hydroponical plants experiments were coupled with sorption experiments to study synergy effects. These data were used to develop a mass balance fitting model of Se uptake and partitioning. Adsorption was well-described by Langmuir isotherms, despite competing anions, however, a certain percentage of Se always remained bio-unavailable to the plant. Uptake of selenate or selenite by transporters into the rice plant was fitted with the non-time differentiated Michaelis-Menten equation. Subsequent sequestration of Se to the shoot was better described using a substrate-inhibited variation of the Michaelis-Menten equation. These fitted parameters were then integrated into a mass balance model of Se transfer.
Assuntos
Oryza/metabolismo , Plântula/química , Selênio/metabolismo , Disponibilidade Biológica , Transporte Biológico , Humanos , Hidroponia , Nitratos/química , Nitratos/metabolismo , Avaliação Nutricional , Oryza/química , Fosfatos/química , Raízes de Plantas/química , Raízes de Plantas/crescimento & desenvolvimento , Selênio/toxicidadeRESUMO
Selenium (Se) is an important micronutrient but also a strong toxin with a narrow tolerance range for many organisms. As such, a globally heterogeneous Se distribution in soils is responsible for various disease patterns (i.e. Se excess and deficiency) and environmental problems, whereby plants play a key role for the Se entrance into the biosphere. Selenium isotope variations were proved to be a powerful tracer for redox processes and are therefore promising for the exploration of the species dependent Se metabolism in plants and the Se cycling within the Critical Zone. Plant cultivation setups enable systematic controlled investigations, but samples derived from them-plant tissue and phytoagar-are particularly challenging and require specific preparation and purification steps to ensure precise and valid Se isotope analytics performed with HG-MC-ICP-MS. In this study, different methods for the entire process from solid tissue preparation to Se isotope measurements were tested, optimized and validated. A particular microwave digestion procedure for plant tissue and a vacuum filtration method for phytoagar led to full Se recoveries, whereby unfavorable organic residues were reduced to a minimum. Three purification methods predominantly described in the literature were systematically tested with pure Se solution, high concentrated multi-element standard solution as well as plant and phytoagar as target matrices. All these methods efficiently remove critical matrix elements, but differ in Se recovery and organic residues. Validation tests doping Se-free plant material and phytoagar with a reference material of known Se isotope composition revealed the high impact of organic residues on the accuracy of MC-ICP-MS measurements. Only the purification method with no detectable organic residues, hydride generation and trapping, results in valid mass bias correction for plant samples with an average deviation to true δ82/76Se values of 0.2 and a reproducibility (2 SD) of ± 0.2 . For phytoagar this test yields a higher deviation of 1.1 from the true value and a 2 SD of ± 0.1 . The application of the developed methods to cultivated plants shows sufficient accuracy and precision and is a promising approach to resolve plant internal Se isotope fractionations, for which respective δ82/76Se values of +2.3 to +3.5 for selenate and +1.2 to +1.9 for selenite were obtained.
Assuntos
Oryza/química , Selênio/análise , Selênio/isolamento & purificação , Ágar , Isótopos/análise , Isótopos/isolamento & purificação , Micro-Ondas , Folhas de Planta/química , Raízes de Plantas/química , Reprodutibilidade dos Testes , VácuoRESUMO
The liver is the main site for drug and xenobiotics metabolism, including inactivation or bioactivation. In order to improve the predictability of drug safety and efficacy in clinical development, and to facilitate the evaluation of the potential human health effects from exposure to environmental contaminants, there is a critical need to accurately model human organ systems such as the liver in vitro. We are developing a microphysiological system (MPS) based on a new commercial microfluidic platform (Nortis, Inc.) that can utilize primary liver cells from multiple species (e.g., rat and human). Compared to conventional monolayer cell culture, which typically survives for 5-7days or less, primary rat or human hepatocytes in an MPS exhibited higher viability and improved hepatic functions, such as albumin production, expression of hepatocyte marker HNF4α and canaliculi structure, for up to 14days. Additionally, induction of Cytochrome P450 (CYP) 1A and 3A4 in cryopreserved human hepatocytes was observed in the MPS. The acute cytotoxicity of the potent hepatotoxic and hepatocarcinogen, aflatoxin B1, was evaluated in human hepatocytes cultured in an MPS, demonstrating the utility of this model for acute hepatotoxicity assessment. These results indicate that MPS-cultured hepatocytes provide a promising approach for evaluating chemical toxicity in vitro.
Assuntos
Técnicas de Cultura de Células , Doença Hepática Induzida por Substâncias e Drogas , Avaliação Pré-Clínica de Medicamentos/métodos , Testes de Toxicidade/métodos , Adulto , Aflatoxina B1/toxicidade , Animais , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Criança , Citocromo P-450 CYP1A1/metabolismo , Citocromo P-450 CYP1A2/metabolismo , Citocromo P-450 CYP3A/metabolismo , Feminino , Fator 4 Nuclear de Hepatócito/metabolismo , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Ratos , Adulto JovemRESUMO
AIMS: Although the generation of linear lesions by ablation improves success rates in patients with persistent atrial fibrillation (AF), the procedure has been considered unsuitable for cryoablation balloon catheter technologies. We developed a technique for linear ablations, using second-generation cryoballoon technology. METHODS AND RESULTS: This was a single-arm, prospective study in 76 patients with persistent AF treated consecutively at our centre. Cryoablation was performed using a 28 mm second-generation cryoballoon. The first cryoenergy application was performed in close proximity to the position during isolation of the left superior pulmonary vein (PV). Sequential overlapping freezes were applied along the left atrial (LA) roof by slight clockwise rotation of the sheath in combination with slight retraction of the sheath and incremental advancement of the cryoballoon, until reaching the original position for right superior PV isolation. The acute endpoint was the creation of a roofline, defined as complete conduction block across the LA roof >120 ms and ascending activation across the posterior LA wall. Acute success in roofline generation was achieved in 88% of patients, applying on average five (median 4-6) freezes with nadir temperature of -40°C (-36 to -44°C). In five patients, conduction block could not be achieved. No phrenic nerve injuries occurred during roofline generation. CONCLUSION: Generation of linear roofline lesions is possible with the second-generation cryoballoon. The technique can be used in combination with PV isolation to treat persistent AF with good acute success rates, short procedure times, and acceptable safety concerns. If validated by further studies, the method would be an appealing alternative to radiofrequency ablation techniques.
Assuntos
Fibrilação Atrial/cirurgia , Criocirurgia/métodos , Átrios do Coração/cirurgia , Veias Pulmonares/cirurgia , Potenciais de Ação , Idoso , Fibrilação Atrial/diagnóstico , Fibrilação Atrial/fisiopatologia , Criocirurgia/efeitos adversos , Técnicas Eletrofisiológicas Cardíacas , Estudos de Viabilidade , Feminino , Átrios do Coração/fisiopatologia , Frequência Cardíaca , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Veias Pulmonares/fisiopatologia , Radiografia Intervencionista , Recidiva , Fatores de Tempo , Resultado do TratamentoRESUMO
Up to 1 billion people are affected by low intakes of the essential nutrient selenium (Se) due to low concentrations in crops. Biofortification of this micronutrient in plants is an attractive way of increasing dietary Se levels. We investigated a promising method of Se biofortification of rice seedlings, as rice is the primary staple for 3 billion people, but naturally contains low Se concentrations. We studied hydroponic Se uptake for 0-2500 ppb Se, potential phyto-toxicological effects of Se and the speciation of Se along the shoots and roots as a function of added Se species, concentrations and other nutrients supplied. We found that rice germinating directly in a Se environment increased plant-Se by factor 2-16, but that nutrient supplementation is required to prevent phyto-toxicity. XANES data showed that selenite uptake mainly resulted in the accumulation of organic Se in roots, but that selenate uptake resulted in accumulation of selenate in the higher part of the shoot, which is an essential requirement for Se to be transported to the grain. The amount of organic Se in the plant was positively correlated with applied Se concentration. Our results indicate that biofortification of seedlings with selenate is a successful method to increase Se levels in rice.
Assuntos
Oryza/metabolismo , Selênio/farmacocinética , Transporte Biológico Ativo , Germinação , Humanos , Hidroponia , Micronutrientes/administração & dosagem , Micronutrientes/farmacocinética , Micronutrientes/toxicidade , Oryza/efeitos dos fármacos , Oryza/crescimento & desenvolvimento , Brotos de Planta/metabolismo , Plântula/metabolismo , Ácido Selênico/administração & dosagem , Ácido Selênico/farmacocinética , Ácido Selênico/toxicidade , Selênio/administração & dosagem , Selênio/toxicidadeRESUMO
A potential strategy to alleviate the aggregation of intrinsically disordered proteins (IDPs) is to maintain the native functional state of the protein by small molecule binding. However, the targeting of the native state of IDPs by small molecules has been challenging due to their heterogeneous conformational ensembles. To tackle this challenge, we applied a high-throughput chemical microarray surface plasmon resonance imaging screen to detect the binding between small molecules and monomeric full-length Tau, a protein linked with the onset of a range of Tauopathies. The screen identified a novel set of drug-like fragment and lead-like compounds that bound to Tau. We verified that the majority of these hit compounds reduced the aggregation of different Tau constructs in vitro and in N2a cells. These results demonstrate that Tau is a viable receptor of drug-like small molecules. The drug discovery approach that we present can be applied to other IDPs linked to other misfolding diseases such as Alzheimer's and Parkinson's diseases.
Assuntos
Fármacos Neuroprotetores/farmacologia , Tauopatias/tratamento farmacológico , Tauopatias/metabolismo , Proteínas tau/metabolismo , Animais , Benzotiazóis , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Corantes Fluorescentes , Ensaios de Triagem em Larga Escala , Humanos , Camundongos , Análise em Microsséries , Microscopia de Fluorescência , Estrutura Molecular , Fármacos Neuroprotetores/química , Agregados Proteicos/efeitos dos fármacos , Multimerização Proteica/efeitos dos fármacos , Tiazóis , Proteínas tau/genéticaRESUMO
INTRODUCTION: A noninvasive 3D mapping technique (ECVUE™, CardioInsight Inc., Cleveland) maps the origin and mechanisms of various arrhythmias without catheterizing the heart. METHODS: Thirty-three patients (3 centers, mean 45.0 ± 14.6 years,) with symptomatic premature ventricular complexes (24 PVCs), focal atrial tachycardias (2 ATs), and manifest accessory pathways (7 WPW syndromes) were prospectively explored using 3D, noninvasive bedside electrocardiomapping. The location of origin of the focal arrhythmia was first determined using noninvasive mapping. Subsequently, a stimulus artifact was delivered at this site to confirm and evaluate the precise location of the mapped focal origin. The procedural parameters and clinical efficacy were studied. RESULTS: Ablation was successful in 32/33 (97%) patients (PVCs: 13 right, 10 left, 1 septal; WPW: 3 left, 3 right; ATs: 2 left) without complications. The time from catheterization to permanent arrhythmia elimination/termination, RF duration, skin-to-skin procedural duration, and fluoroscopic exposure were median 16, 3.98, 71, and 11.9 minutes (for n = 29), respectively. At mean 24.7 ± 3.7 months of follow-up, 31 patients remain arrhythmia-free after a single procedure. One patient (right WPW syndrome) required repeat ablation 1 month later. One patient had recurrence of PVCs and is now deceased. The cumulative radiation (CT scan and fluoroscopy) exposure was median 7.57 mSv. CONCLUSION: ECVUE(TM) is a noninvasive tool allowing rapid preprocedural localization of focal arrhythmia and enables the electrophysiologist with highly specific information to direct RF delivery at the source of the arrhythmia with minimal intracardiac mapping.
Assuntos
Feixe Acessório Atrioventricular/cirurgia , Ablação por Cateter/métodos , Técnicas Eletrofisiológicas Cardíacas , Sistema de Condução Cardíaco/cirurgia , Taquicardia Supraventricular/cirurgia , Complexos Ventriculares Prematuros/cirurgia , Feixe Acessório Atrioventricular/diagnóstico , Feixe Acessório Atrioventricular/fisiopatologia , Potenciais de Ação , Adulto , Ablação por Cateter/efeitos adversos , Eletrocardiografia , Europa (Continente) , Estudos de Viabilidade , Feminino , Sistema de Condução Cardíaco/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Duração da Cirurgia , Testes Imediatos , Valor Preditivo dos Testes , Estudos Prospectivos , Doses de Radiação , Radiografia Intervencionista , Recidiva , Taquicardia Supraventricular/diagnóstico , Taquicardia Supraventricular/fisiopatologia , Fatores de Tempo , Resultado do Tratamento , Complexos Ventriculares Prematuros/diagnóstico , Complexos Ventriculares Prematuros/fisiopatologiaRESUMO
Preprocedural detailed characterization of premature ventricular complexes before ablation, currently limited to the 12-lead electrocardiogram, may aid in planning and improve procedural outcomes. This article summarizes current published data on feasibility, accuracy, and impact on clinical outcomes of a novel, three-dimensional, noninvasive, single-beat mapping system (ECVUE, CardioInsight). ECVUE technology offers premature ventricular complex characterization and localization with clinically relevant accuracy and performance superior to the surface electrocardiogram. With its noninvasive and single beat advantages, ECVUE has the potential to simplify mapping, and reduce ablation and procedural time.
Assuntos
Ablação por Cateter/métodos , Eletrocardiografia/métodos , Técnicas Eletrofisiológicas Cardíacas/métodos , Imageamento Tridimensional/métodos , Complexos Ventriculares Prematuros/cirurgia , Humanos , Complexos Ventriculares Prematuros/diagnóstico , Complexos Ventriculares Prematuros/fisiopatologiaRESUMO
Soil and groundwater samples were collected for bulk elemental analyses in particular for selenium (Se) concentrations from six agricultural sites located in states of Punjab and Haryana in North-West India. Toxic concentrations of Se (45-341 µg L(-1)) were present in groundwater (76 m deep) of Jainpur and Barwa villages in Punjab. Selenium enrichments were also found in top soil layers (0-15 cm) of Jainpur (2.3-11.6 mg kg(-1)) and Barwa (3.1 mg kg(-1)). Mineralogical analyses confirmed silicates and phyllosilicates as main components of these soils, also reflected by the high content of SiO(2) (40-62 wt.%), Al(2)O(3) (9-21 wt.%) and K(2)O (2.2-3.2 wt.%). Prevailing intensive irrigation practices in Punjab with Se enriched groundwater may be the cause of Se accumulation in soils. Sequential extraction revealed >50% Se bioavailability in Jainpur soils. Appearance of selenite was observed in some of the batch assays with soil slurries under reducing conditions. Although safe Se concentrations were found in Hisar, Haryana, yet high levels of As, Mo and U present in groundwater indicated its unsuitability for drinking purposes. Detailed biogeochemical studies of Se in sediments or groundwater of Punjab are not available so far; intensive investigations should be started for better understanding of the problem of Se toxicity.
Assuntos
Selênio/análise , Selênio/toxicidade , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Poluentes Químicos da Água/análise , Agricultura , Exposição Ambiental , Monitoramento Ambiental/métodos , Humanos , Índia , Resíduos Industriais , Modelos Químicos , Unhas/efeitos dos fármacos , Unhas/patologia , Selenito de Sódio/análise , Selenito de Sódio/toxicidade , Solo , Água/química , Microbiologia da Água , Poluição da ÁguaRESUMO
OBJECTIVES: The purpose of this study was to investigate the efficacy safety of the novel cryoballoon device (Arctic Front, Cryocath, Quebec, Canada). BACKGROUND: Antral pulmonary vein (PV) ablation with radiofrequency energy is widely used as a strategy for catheter ablation of paroxysmal atrial fibrillation (PAF). A novel double lumen cryoballoon catheter was designed for circumferential pulmonary vein isolation (PVI) with the cryoablation technique. METHODS: We consecutively enrolled 346 patients with symptomatic, drug refractory paroxysmal (n = 293) or persistent (n = 53) atrial fibrillation (AF). In all patients, PVI of all targeted PVs was the therapeutic aim. The primary end points of this nonrandomized study were: 1) acute isolation rate of targeted PV; and 2) first electrocardiogram-documented recurrence of AF. The secondary end point was occurrence of PV stenosis or atrio-esophageal fistula. RESULTS: The 1,360 of 1,403 PVs (97%) were targeted with balloons or balloons in combination with the use of Freezor Max (Cryocath). We found that ablation with the cryoballoon resulted in maintenance of sinus rhythm in 74% of patients with PAF and 42% of patients with persistent AF. No PV narrowing occurred. The most frequent complication was right phrenic nerve palsy observed during cryoballoon ablation at the right superior PV. CONCLUSIONS: Pulmonary vein isolation with a new cryoballoon technique is feasible. Sinus rhythm can be maintained in the majority of patients with PAF by circumferential PVI using a cryoballoon ablation system. Cryoablation was less effective in patients with persistent AF than in patients with PAF.
Assuntos
Angioplastia com Balão/métodos , Fibrilação Atrial/terapia , Crioterapia , Veias Pulmonares , Idoso , Angioplastia com Balão/instrumentação , Fibrilação Atrial/fisiopatologia , Técnicas Eletrofisiológicas Cardíacas , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Fatores de Tempo , Resultado do TratamentoRESUMO
BACKGROUND: Aim of this invasive study was to characterize and quantify changes in left ventricular (LV) systolic function due to sequential biventricular pacing (BV) as compared to right atrial triggered simultaneous BV (BV(0)), LV, and right ventricular (RV) pacing in patients with congestive heart failure (CHF). METHODS: In 22 CHF patients, all in sinus rhythm, temporary multisite pacing was performed prior to implantation of a permanent system. LV systolic function was evaluated invasively by the maximum rate of LV pressure increase (dP/dt(max)). Sequential BV pacing was performed with preactivation of either ventricle at 20-80 ms. RESULTS: In comparison to RV pacing, LV and BV(0) pacing increased dP/dt(max) by 33.9 +/- 19.3% and 34.0 +/- 22.6%, respectively (P < 0.001). In 9 patients, optimized sequential BV pacing further improved dP/dt(max) by 8.5 +/- 4.8% compared to BV(0) (range 3.3-17.1, P < 0.05). In 10 patients exhibiting a PR interval < or =200 ms, LV pacing was either superior (n = 6) or equal to BV(0) pacing (n = 4). In these 10 patients, LV pacing yielded a 7.4 +/- 8.0% higher dP/dt(max) than BV(0) pacing (P < 0.05). CONCLUSIONS: Using sequential BV pacing, generally with LV preactivation, moderate improvements in LV systolic function can be achieved in selected patients. Baseline PR interval may aid in the selection of the optimum cardiac resynchronization therapy (CRT) mode, favoring LV pacing in patients with a PR interval < or =200 ms.
Assuntos
Estimulação Cardíaca Artificial/métodos , Insuficiência Cardíaca/terapia , Disfunção Ventricular Esquerda/terapia , Idoso , Cateterismo Cardíaco , Distribuição de Qui-Quadrado , Técnicas Eletrofisiológicas Cardíacas , Feminino , Insuficiência Cardíaca/fisiopatologia , Hemodinâmica/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Disfunção Ventricular Esquerda/fisiopatologiaRESUMO
Quercetin is one of the dietary-derived flavonoids that are held responsible for the beneficial effects of red wine drinking in coronary artery disease known as the "French paradox". We examined whether quercetin modulates endothelial function by influencing Ca2+-activated K+ channels with large conductance (BK(Ca)) in cultured human endothelial cells. Membrane potential and intracellular Ca2+ concentrations of cultured human endothelial cells derived from umbilical cord veins (HUVEC) were measured using the fluorescence dyes DiBAC, and FURA-2, respectively. NO production was examined using a cGMP radioimmunoassay. HUVEC proliferation was analyzed by cell counts and thymidine incorporation. A dose-dependent hyperpolarization of HUVEC was recorded when quercetin was added (5-100 micromol/L). The maximum effect (50 micromol/L) was significantly reduced by the addition of the highly selective BK(Ca) inhibitor iberiotoxin (100 nmol/L), but not by blockers of other Ca2+-activated K+ channels (n = 30; p < 0.05). This BK(Ca)-induced hyperpolarization caused a transmembrane Ca2+ influx, because the quercetin-induced increase of intracellular Ca2+ was blocked by iberiotoxin, or by applying 2-aminoethoxydiphenylborate (100 micromol/L)--an inhibitor of capacitative Ca2+ entry (n = 30; p < 0.05). Quercetin-induced cGMP levels were significantly reduced by the eNOS-inhibitor l-NMMA (300 micromol/L), and by iberiotoxin (n = 10; p < 0.05). Endothelial proliferation was significantly reduced by 56 % when cells were incubated with quercetin (n = 12; p < 0.05). This effect was due to the increased NO production, because it was reversed when the cells were treated with a combination of quercetin and l-NMMA. In conclusion quercetin improves endothelial dysfunction by increasing NO synthesis involving BK(Ca)-dependent membrane hyperpolarization-induced capacitative Ca 2+ entry. Increased NO production is responsible for the quercetin-dependent inhibition of endothelial proliferation.