RESUMO
Candida albicans is an opportunistic fungal producing both superficial and systemic infections in immunocompromised patients. Furthermore, it has been described an increase in the frequency of infections which have become refractory to standard antifungal therapy. Photodynamic antimicrobial chemotherapy (PACT) is a potential antimicrobial therapy that combines visible light and a nontoxic dye, known as a photosensitizer, producing reactive oxygen species (ROS) that can kill the treated cells. The objective of this study was to investigate the effects of PACT, using chlorin e6, as a photosensitizer on C. albicans. In this work, we studied the effect of PACT on both cell growth and biofilm formation by C. albicans. In addition, both ROS production and cell permeability were determined after PACT. PACT inhibited both growth and biofilm formation by C. albicans. We have also observed that PACT increased both ROS production (six times) and cell membrane permeability (five times) in C. albicans. PACT decreased both cell growth and biofilm development. The effect of PACT using chlorin e6 on C. albicans could be associated with an increase in ROS production, which could increase cell permeability, producing permanent damage to the cell membranes, leading to the cell death.
Assuntos
Anti-Infecciosos/farmacologia , Biofilmes/crescimento & desenvolvimento , Candida albicans/fisiologia , Permeabilidade da Membrana Celular/efeitos dos fármacos , Permeabilidade da Membrana Celular/efeitos da radiação , Fármacos Fotossensibilizantes/farmacologia , Porfirinas/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Biofilmes/efeitos dos fármacos , Biofilmes/efeitos da radiação , Candida albicans/efeitos dos fármacos , Clorofilídeos , Testes de Sensibilidade MicrobianaRESUMO
Bio-effects mediated by non-ionizing electromagnetic fields (EMF) have become a hot topic of research in the last decades. This interest has been triggered by a growing public concern about the rapid expansion of telecommunication devices and possible consequences of their use on human health. Despite a feasibility study of potential negative impacts, the therapeutic advantages of EMF could be effectively harnessed for the treatment of cancer and other diseases. This review aims to examine recent findings relating to the mechanisms of action underlying the bio-effects induced by non-ionizing EMF. The potential of non-thermal and thermal effects is discussed in the context of possible applications for the induction of apoptosis, formation of reactive oxygen species, and increase of membrane permeability in malignant cells. A special emphasis has been put on the combination of EMF with magnetic nano-particles and ultrasound for cancer treatment. The review encompasses both human and animal studies.
Assuntos
Apoptose/efeitos da radiação , Permeabilidade da Membrana Celular/efeitos da radiação , Temperatura Alta , Magnetoterapia/efeitos adversos , Magnetoterapia/métodos , Neoplasias/terapia , Radiação não Ionizante/efeitos adversos , Espécies Reativas de Oxigênio/metabolismo , Animais , Humanos , Nanopartículas/uso terapêutico , Ultrassonografia/métodosRESUMO
The opportunistic fungal Candida albicans is able to produce both superficial and systemic infections in immunocompromised patients. Photodynamic antimicrobial chemotherapy (PACT) is a process that combines visible light and a photosensitizer, producing reactive oxygen species (ROS) that can kill the treated cells and has been presented as a potential antimicrobial therapy. In this work, we study the effects of PACT, using toluidine blue (TB) as a photosensitizer drug, on ROS production and cell damage and the ability of C. albicans to form biofilm. A significant decrease was observed in the cell growth after PACT in a TB concentration-dependent manner. This effect was dependent on the incubation time after PACT. In addition, an increase in both the ROS production and cell permeability, after PACT, in a TB concentration-dependent manner was observed. PACT, using 0.1 mg/ml TB was able to reduce biofilm formation in 30, 50, and 62%, in cells submitted to incubation times of 1, 2, and 3 h, respectively. These results suggested that PACT, using TB, is able to decrease both growth and biofilm formation by C. albicans, possibly by a mechanism evolving both ROS production and the increase in the cell permeability.
Assuntos
Biofilmes/efeitos dos fármacos , Candida albicans/efeitos dos fármacos , Permeabilidade da Membrana Celular/efeitos dos fármacos , Fotoquimioterapia , Espécies Reativas de Oxigênio/metabolismo , Anti-Infecciosos/farmacologia , Biofilmes/efeitos da radiação , Candida albicans/fisiologia , Candida albicans/efeitos da radiação , Candidíase/tratamento farmacológico , Permeabilidade da Membrana Celular/efeitos da radiação , Humanos , Luz , Testes de Sensibilidade Microbiana , Permeabilidade , Fármacos Fotossensibilizantes/farmacologia , Cloreto de Tolônio/farmacologiaRESUMO
BACKGROUND: Tick embryogenesis is a metabolically intensive process developed under tightly controlled conditions and whose components are poorly understood. METHODS: In order to characterize the role of AKT (protein kinase B) in glycogen metabolism and cell viability, glycogen determination, identification and cloning of an AKT from Rhipicephalus microplus were carried out, in parallel with experiments using RNA interference (RNAi) and chemical inhibition. RESULTS: A decrease in glycogen content was observed when AKT was chemically inhibited by 10-DEBC treatment, while GSK3 inhibition by alsterpaullone had an opposing effect. RmAKT ORF is 1584-bp long and encodes a polypeptide chain of 60.1 kDa. Phylogenetic and sequence analyses showed significant differences between vertebrate and tick AKTs. Either AKT or GSK3 knocked down cells showed a 70% reduction in target transcript levels, but decrease in AKT also reduced glycogen content, cell viability and altered cell membrane permeability. However, the GSK3 reduction promoted an increase in glycogen content. Additionally, either GSK3 inhibition or gene silencing had a protective effect on BME26 viability after exposure to ultraviolet radiation. R. microplus AKT and GSK3 were widely expressed during embryo development. Taken together, our data support an antagonistic role for AKT and GSK3, and strongly suggest that such a signaling axis is conserved in tick embryos, with AKT located upstream of GSK3. GENERAL SIGNIFICANCE: The AKT/GSK3 axis is conserved in tick in a way that integrates glycogen metabolism and cell survival, and exhibits phylogenic differences that could be important for the development of novel control methods.
Assuntos
Proteínas de Artrópodes/genética , Quinase 3 da Glicogênio Sintase/genética , Glicogênio/metabolismo , Glicogenólise/genética , Proteínas Proto-Oncogênicas c-akt/genética , Rhipicephalus/genética , Animais , Proteínas de Artrópodes/antagonistas & inibidores , Proteínas de Artrópodes/metabolismo , Benzazepinas/farmacologia , Linhagem Celular , Permeabilidade da Membrana Celular/efeitos da radiação , Sobrevivência Celular/efeitos da radiação , Clonagem Molecular , Embrião não Mamífero , Regulação da Expressão Gênica/efeitos da radiação , Glicogênio/genética , Quinase 3 da Glicogênio Sintase/antagonistas & inibidores , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogenólise/efeitos da radiação , Indóis/farmacologia , Fases de Leitura Aberta , Oxazinas/farmacologia , Filogenia , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Interferente Pequeno/genética , Rhipicephalus/embriologia , Rhipicephalus/metabolismo , Homologia de Sequência de Aminoácidos , Transdução de Sinais/efeitos da radiação , Especificidade da Espécie , Raios UltravioletaRESUMO
Photodynamic antimicrobial chemotherapy (PACT) is a potential antimicrobial therapy that combines light and a photosensitizing drug, promoting a phototoxic effect on the treated cells, in general via oxidative damage. In this work we studied the effect of PACT, using methylene blue (MB), on the permeability of Candida albicans membrane. Our results demonstrated that the combination of MB and laser (684 nm) promoted a decrease in Candida growth. The inhibition was more pronounced in the presence of 0.05 mg/ml MB and with an energy density of 28 J/cm(2). The decrease in Candida growth was associated with an increase in membrane permeabilization. Thus, we suggest that a PACT mechanism using MB can be related to damage in the plasma membranes of the cells.
Assuntos
Candida albicans/efeitos dos fármacos , Candida albicans/efeitos da radiação , Permeabilidade da Membrana Celular/efeitos dos fármacos , Permeabilidade da Membrana Celular/efeitos da radiação , Lasers , Azul de Metileno/farmacologia , Fotoquimioterapia , FluorometriaRESUMO
Irradiation of blood derivatives is employed in blood banks to avoid transfusion-associated graft-vs-host disease. As irradiation can damage membranes and membrane proteins by generation of reactive oxygen species, we investigated whether the membrane permeability, Na(+),K(+)-ATPase, and Ca(2+)-ATPase from red blood cell plasma membranes were altered by gamma-irradiation. Whole blood was collected from healthy donors and concentrated to 90% cell fraction. Within 24 h of collection, blood concentrates were irradiated with 25 Gy of gamma-radiation. At days 1, 7, 14, and 28 post-irradiation, fractions were removed and centrifuged. Na(+),K(+)-ATPase and Ca(2+)-ATPase activities from ghost membranes were assessed by gamma-(32)P-ATP hydrolysis. The Na(+),K(+)-ATPase was not immediately affected by irradiation, but it was inhibited by 40% by day 14 and until day 28. The Ca(2+)-ATPase was unaltered by irradiation. The rate and the maximal (45)Ca(2+) uptake from re-sealed inside-out vesicles were reduced, and the passive efflux of (45)Ca(2+) was increased. Thus, irradiation of blood concentrates increased the plasma membrane permeability to monovalent and divalent cations and would change ion homeostasis and cell function. We recommend the use of irradiated blood within a period shorter than 14 days after irradiation.
Assuntos
Permeabilidade da Membrana Celular/efeitos da radiação , Membrana Eritrocítica/efeitos da radiação , Raios gama/efeitos adversos , ATPase Trocadora de Sódio-Potássio/efeitos da radiação , Preservação de Sangue/métodos , Membrana Eritrocítica/enzimologia , Transfusão de Eritrócitos/métodos , Doença Enxerto-Hospedeiro/prevenção & controle , HumanosRESUMO
The application of electric pulses in cells increases membrane permeability. This phenomenon is called electroporation. Current electroporation models do not explain all experimental findings: part of this problem is due to the limitations of numerical methods. The Equivalent Circuit Method (ECM) was developed in an attempt to solve electromagnetic problems in inhomogeneous and anisotropic media. ECM is based on modeling of the electrical transport properties of the medium by lumped circuit elements as capacitance, conductance, and current sources, representing the displacement, drift, and diffusion current, respectively. The purpose of the present study was to implement a 2-D cell Model Development Environment (MDE) of ionic transport process, local anisotropy around cell membranes, biological interfaces, and the dispersive behaviour of tissues. We present simulations of a single cell, skeletal muscle, and polygonal cell arrangement. Simulation of polygonal form indicates that the potential distribution depends on the geometrical form of cell. The results demonstrate the importance of the potential distributions in biological cells to provide strong evidences for the understanding of electroporation.
Assuntos
Permeabilidade da Membrana Celular/fisiologia , Permeabilidade da Membrana Celular/efeitos da radiação , Membrana Celular/fisiologia , Membrana Celular/efeitos da radiação , Fenômenos Fisiológicos Celulares/efeitos da radiação , Eletroporação/métodos , Modelos Biológicos , Simulação por Computador , Relação Dose-Resposta à Radiação , Estimulação Elétrica/métodos , Campos Eletromagnéticos , Análise Numérica Assistida por Computador , Doses de RadiaçãoRESUMO
It is known that the incubation, in a buffer, of UV-irradiated E. coli cells results in viability increase, this phenomenon had been called liquid holding recovery (LHR). We have studied the cellular constituents release during LHR and verified that releasing rate is dose-dependent. LHR was also observed after nitrogen-mustard treatment and it is not blocked by caffeine. So, we suggest that LHR expression is not always a rec-gene dependent function and, probably, the survival increase could be explained by (a) DNA-repair, (b) reversible membrane damage and (c) cellular multiplication.