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Mesial temporal lobe epilepsy (MTLE), the most common form of focal epilepsy in adults, is often refractory to medication and associated with hippocampal sclerosis. Deep brain stimulation represents an alternative treatment option for drug-resistant patients who are ineligible for resective brain surgery. In clinical practice, closed-loop stimulation at high frequencies is applied to interrupt ongoing seizures, yet has (i) a high incidence of false detections; (ii) the drawback of delayed seizure-suppressive intervention; and (iii) limited success in sclerotic tissue. As an alternative, low-frequency stimulation (LFS) has been explored recently in patients with focal epilepsies. In preclinical epilepsy models, hippocampal LFS successfully prevented seizures when applied continuously. Since it would be advantageous to reduce the stimulation load, we developed a protocol for on-demand LFS. Given the importance of the hippocampus for navigation and memory, we investigated potential consequences of LFS on hippocampal function. To this end, we used the intrahippocampal kainate mouse model, which recapitulates the key features of MTLE, including spontaneous seizure activity and hippocampal sclerosis. Specifically, our online detection algorithm monitored epileptiform activity in hippocampal local field potential recordings and identified short epileptiform bursts preceding focal seizure clusters, triggering hippocampal LFS to stabilize the network state. To probe behavioural performance, we tested the acute influence of LFS on anxiety-like behaviour in the light-dark box test, spatial and non-spatial memory in the object location memory and novel object recognition test, as well as spatial navigation and long-term memory in the Barnes maze. On-demand LFS was almost as effective as continuous LFS in preventing focal seizure clusters but with a significantly lower stimulation load. When we compared the behavioural performance of chronically epileptic mice to healthy controls, we found that both groups were equally mobile, but epileptic mice displayed an increased anxiety level, altered spatial learning strategy and impaired memory performance. Most importantly, with the application of hippocampal LFS before behavioural training and test sessions, we could rule out deleterious effects on cognition and even show an alleviation of deficits in long-term memory recall in chronically epileptic mice. Taken together, our findings may provide a promising alternative to current therapies, overcoming some of their major limitations, and inspire further investigation of LFS for seizure control in focal epilepsy syndromes.
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Epilepsia del Lóbulo Temporal , Epilepsia , Esclerosis del Hipocampo , Humanos , Ratones , Animales , Convulsiones , Hipocampo , Epilepsia del Lóbulo Temporal/terapiaRESUMEN
The repair of toxic double-strand breaks (DSB) is critical for the maintenance of genome integrity. The major mechanisms that cope with DSB are: homologous recombination (HR) and classical or alternative nonhomologous end joining (C-NHEJ versus A-EJ). Because these pathways compete for the repair of DSB, the choice of the appropriate repair pathway is pivotal. Among the mechanisms that influence this choice, deoxyribonucleic acid (DNA) end resection plays a critical role by driving cells to HR, while accurate C-NHEJ is suppressed. Furthermore, end resection promotes error-prone A-EJ. Increasing evidence define Poly(ADP-ribose) polymerase 3 (PARP3, also known as ARTD3) as an important player in cellular response to DSB. In this work, we reveal a specific feature of PARP3 that together with Ku80 limits DNA end resection and thereby helps in making the choice between HR and NHEJ pathways. PARP3 interacts with and PARylates Ku70/Ku80. The depletion of PARP3 impairs the recruitment of YFP-Ku80 to laser-induced DNA damage sites and induces an imbalance between BRCA1 and 53BP1. Both events result in compromised accurate C-NHEJ and a concomitant increase in DNA end resection. Nevertheless, HR is significantly reduced upon PARP3 silencing while the enhanced end resection causes mutagenic deletions during A-EJ. As a result, the absence of PARP3 confers hypersensitivity to anti-tumoral drugs generating DSB.
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Proteínas de Ciclo Celular/fisiología , Reparación del ADN por Unión de Extremidades , Poli(ADP-Ribosa) Polimerasas/fisiología , Reparación del ADN por Recombinación , Antígenos Nucleares/metabolismo , Antineoplásicos/farmacología , Proteína BRCA1/metabolismo , Línea Celular Tumoral , Roturas del ADN de Doble Cadena , ADN Helicasas/metabolismo , Proteínas de Unión al ADN/metabolismo , Ensayos de Selección de Medicamentos Antitumorales , Etopósido/farmacología , Humanos , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Autoantígeno Ku , Proteínas Nucleares/metabolismo , Procesamiento Proteico-Postraduccional , Transporte de Proteínas , Proteína de Replicación A/metabolismo , Proteína 1 de Unión al Supresor Tumoral P53RESUMEN
Discrete choice experiments (DCEs) become increasingly popular to value outcomes for health economic studies and gradually gain acceptance as an input into policy decisions. Developing attributes is a key aspect for the design of DCEs, as their results may misguide decision-makers if they are based on an inappropriate set of attributes. However, the area lacks guidance, and current health-related DCE studies vary considerably in their methods of attribute development, with the consequent danger of providing an unreliable input for policy decisions. The aim of this article is to inform the progress toward a more systematic approach to attribute development for DCE studies in health. A systematic review of the published health-related DCE literature was conducted to lay the foundations for a generic framework which was tested in a case study of alcohol misuse interventions. Four stages of a general attribute development process emerged: (i) raw data collection; (ii) data reduction; (iii) removing inappropriate attributes; and (iv) wording. The case study compared and contrasted a qualitative and mixed-methods approach for the development of attributes for DCEs in the area of alcohol misuse interventions. This article provides a reference point for the design of future DCE experiments in health.
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BACKGROUND: The European Innovation Partnership on Active and Healthy Ageing (EIP on AHA) is a European Commission led policy initiative to address the challenges of demographic change in Europe. For monitoring the health and economic impact of the social and technological innovations carried out by more than 500 stakeholder's groups ('commitments') participating in the EIP on AHA, a generic and flexible web-based monitoring and assessment tool is currently being developed. AIM: This paper describes the approach for developing and implementing this web-based tool, its main characteristics and capability to provide specific outcomes that are of value to the developers of an intervention, as well as a series of case studies planned before wider rollout. METHODS: The tool builds up from a variety of surrogate endpoints commonly used across the diverse set of EIP on AHA commitments in order to estimate health and economic outcomes in terms of incremental changes in quality adjusted life years (QALYs) as well as health and social care utilisation. A highly adaptable Markov model with initially three mutually exclusive health states ('baseline health', 'deteriorated health' and 'death') provides the basis for the tool which draws from an extensive database of epidemiological, economic and effectiveness data; and also allows further customisation through remote data entry enabling more accurate and context specific estimation of intervention impact. Both probabilistic sensitivity analysis and deterministic scenario analysis allow assessing the impact of parameter uncertainty on intervention outcomes. A set of case studies, ranging from the pre-market assessment of early healthcare technologies to the retrospective analysis of established care pathways, will be carried out before public rollout, which is envisaged end 2015. CONCLUSION: Monitoring the activities carried out within the EIP on AHA requires an approach that is both flexible and consistent in the way health and economic impact is estimated across interventions and commitments. The added value for users of the MAFEIP-tool is its ability to provide an early assessment of the likelihood that interventions in their current design will achieve the anticipated impact, and also to identify what drives interventions' effectiveness or efficiency to guide further design, development or evaluation.
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Envejecimiento , Técnicas de Apoyo para la Decisión , Aplicaciones de la Informática Médica , Evaluación de Resultado en la Atención de Salud/métodos , Conducta Cooperativa , Europa (Continente) , Humanos , Innovación OrganizacionalRESUMEN
The ADP ribosyl transferase [poly(ADP-ribose) polymerase] ARTD3(PARP3) is a newly characterized member of the ARTD(PARP) family that catalyzes the reaction of ADP ribosylation, a key posttranslational modification of proteins involved in different signaling pathways from DNA damage to energy metabolism and organismal memory. This enzyme shares high structural similarities with the DNA repair enzymes PARP1 and PARP2 and accordingly has been found to catalyse poly(ADP ribose) synthesis. However, relatively little is known about its in vivo cellular properties. By combining biochemical studies with the generation and characterization of loss-of-function human and mouse models, we describe PARP3 as a newcomer in genome integrity and mitotic progression. We report a particular role of PARP3 in cellular response to double-strand breaks, most likely in concert with PARP1. We identify PARP3 as a critical player in the stabilization of the mitotic spindle and in telomere integrity notably by associating and regulating the mitotic components NuMA and tankyrase 1. Both functions open stimulating prospects for specifically targeting PARP3 in cancer therapy.
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Proteínas de Ciclo Celular/metabolismo , Roturas del ADN de Doble Cadena , Inestabilidad Genómica/genética , Mitosis/genética , Poli(ADP-Ribosa) Polimerasas/metabolismo , Huso Acromático/fisiología , Adenosina Difosfato/metabolismo , Animales , Antígenos Nucleares/metabolismo , Western Blotting , Línea Celular Tumoral , Ensayo de Unidades Formadoras de Colonias , Ensayo Cometa , Cartilla de ADN/genética , Técnica del Anticuerpo Fluorescente Indirecta , Inestabilidad Genómica/fisiología , Humanos , Inmunoprecipitación , Hibridación Fluorescente in Situ , Espectrometría de Masas , Ratones , Ratones Noqueados , Microscopía por Video , Mitosis/fisiología , Proteínas Asociadas a Matriz Nuclear/metabolismo , Poli(ADP-Ribosa) Polimerasas/deficiencia , Tanquirasas/metabolismoRESUMEN
Brain interfaces that can stimulate neurons, cause minimal damage, and work for a long time will be central for future neuroprosthetics. Here, the long-term performance of highly flexible, thin polyimide shanks with several small (<15 µm) electrodes during electrical microstimulation of the visual cortex, is reported. The electrodes exhibit a remarkable stability when several billions of electrical pulses are applied in vitro. When the devices are implanted in the primary visual cortex (area V1) of mice and the animals are trained to detect electrical microstimulation, it is found that the perceptual thresholds are 2-20 microamperes (µA), which is far below the maximal currents that the electrodes can withstand. The long-term functionality of the devices in vivo is excellent, with stable performance for up to more than a year and little damage to the brain tissue. These results demonstrate the potential of thin floating electrodes for the long-term restoration of lost sensory functions.
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Electrodos Implantados , Polímeros , Percepción Visual , Animales , Ratones , Percepción Visual/fisiología , Polímeros/química , Ratones Endogámicos C57BL , Prótesis Visuales/química , Estimulación Eléctrica , Corteza Visual/fisiologíaRESUMEN
Extracellular recordings with planar microelectrodes are the gold standard technique for recording the fast action potentials of neurons in the intact brain. The introduction of microfabrication techniques has revolutionized the in vivo recording of neuronal activity and introduced high-density, multi-electrode arrays that increase the spatial resolution of recordings and the number of neurons that can be simultaneously recorded. Despite these innovations, there is still debate about the ideal electrical transfer characteristics of extracellular electrodes. This uncertainty is partly due to the lack of systematic studies comparing electrodes with different characteristics, particularly for chronically implanted arrays over extended time periods. Here a high-density, flexible, and thin-film array is fabricated and tested, containing four distinct electrode types differing in surface material and surface topology and, thus, impedance. It is found that recording quality is strongly related to electrode impedance with signal amplitude and unit yield negatively correlated to impedance. Electrode impedances are stable for the duration of the experiment (up to 12 weeks) and recording quality does not deteriorate. The findings support the expectation from the theory that recording quality will increase as impedance decreases.
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Objective. Electrical stimulation of visual cortex via a neuroprosthesis induces the perception of dots of light ('phosphenes'), potentially allowing recognition of simple shapes even after decades of blindness. However, restoration of functional vision requires large numbers of electrodes, and chronic, clinical implantation of intracortical electrodes in the visual cortex has only been achieved using devices of up to 96 channels. We evaluated the efficacy and stability of a 1024-channel neuroprosthesis system in non-human primates (NHPs) over more than 3 years to assess its suitability for long-term vision restoration.Approach.We implanted 16 microelectrode arrays (Utah arrays) consisting of 8 × 8 electrodes with iridium oxide tips in the primary visual cortex (V1) and visual area 4 (V4) of two sighted macaques. We monitored the animals' health and measured electrode impedances and neuronal signal quality by calculating signal-to-noise ratios of visually driven neuronal activity, peak-to-peak voltages of the waveforms of action potentials, and the number of channels with high-amplitude signals. We delivered cortical microstimulation and determined the minimum current that could be perceived, monitoring the number of channels that successfully yielded phosphenes. We also examined the influence of the implant on a visual task after 2-3 years of implantation and determined the integrity of the brain tissue with a histological analysis 3-3.5 years post-implantation.Main results. The monkeys remained healthy throughout the implantation period and the device retained its mechanical integrity and electrical conductivity. However, we observed decreasing signal quality with time, declining numbers of phosphene-evoking electrodes, decreases in electrode impedances, and impaired performance on a visual task at visual field locations corresponding to implanted cortical regions. Current thresholds increased with time in one of the two animals. The histological analysis revealed encapsulation of arrays and cortical degeneration. Scanning electron microscopy on one array revealed degradation of IrOxcoating and higher impedances for electrodes with broken tips.Significance. Long-term implantation of a high-channel-count device in NHP visual cortex was accompanied by deformation of cortical tissue and decreased stimulation efficacy and signal quality over time. We conclude that improvements in device biocompatibility and/or refinement of implantation techniques are needed before future clinical use is feasible.
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Ceguera , Animales , Haplorrinos , Utah , Microelectrodos , Potenciales de AcciónRESUMEN
Bioelectronic devices have found use at the interface with neural tissue to investigate and treat nervous system disorders. Here, the development and characterization of a very thin flexible bioelectronic implant inserted along the thoracic spinal cord in rats directly in contact with and conformable to the dorsal surface of the spinal cord are presented. There is no negative impact on hind-limb functionality nor any change in the volume or shape of the spinal cord. The bioelectronic implant is maintained in rats for a period of 12 weeks. The first subdural recordings of spinal cord activity in freely moving animals are presented; rats are plugged in via a recording cable and allowed to freely behave and move around on a raised platform. Recordings contained multiple distinct voltage waveforms spatially localize to individual electrodes. This device has great potential to monitor electrical signaling in the spinal cord after an injury and in the future, this implant will facilitate the identification of biomarkers in spinal cord injury and recovery, while enabling the delivery of localized electroceutical and chemical treatments.
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Fenómenos Fisiológicos del Sistema Nervioso , Traumatismos de la Médula Espinal , Animales , Prótesis e Implantes , Ratas , Traumatismos de la Médula Espinal/terapia , Espacio SubduralRESUMEN
BACKGROUND: The 'Physical Activity Care Pathway' (a Pilot for the 'Let's Get Moving' policy) is a systematic approach to integrating physical activity promotion into the primary care setting. It combines several methods reported to support behavioural change, including brief interventions, motivational interviewing, goal setting, providing written resources, and follow-up support. This paper compares costs falling on the UK National Health Service (NHS) of implementing the care pathway using two different recruitment strategies and provides initial insights into the cost of changing physical activity behaviour. METHODS: A combination of a time driven variant of activity based costing, audit data through EMIS and a survey of practice managers provided patient-level cost data for 411 screened individuals. Self reported physical activity data of 70 people completing the care pathway at three month was compared with baseline using a regression based 'difference in differences' approach. Deterministic and probabilistic sensitivity analyses in combination with hypothesis testing were used to judge how robust findings are to key assumptions and to assess the uncertainty around estimates of the cost of changing physical activity behaviour. RESULTS: It cost £53 (SD 7.8) per patient completing the PACP in opportunistic centres and £191 (SD 39) at disease register sites. The completer rate was higher in disease register centres (27.3% vs. 16.2%) and the difference in differences in time spent on physical activity was 81.32 (SE 17.16) minutes/week in patients completing the PACP; so that the incremental cost of converting one sedentary adult to an 'active state' of 150 minutes of moderate intensity physical activity per week amounts to £ 886.50 in disease register practices, compared to opportunistic screening. CONCLUSIONS: Disease register screening is more costly than opportunistic patient recruitment. However, additional costs come with a higher completion rate and better outcomes in terms of behavioural change in patients completing the care pathway. Further research is needed to rigorously evaluate intervention efficiency and to assess the link between behavioural change and changes in quality adjusted life years (QALYs).
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Promoción de la Salud/organización & administración , Actividad Motora , Atención Primaria de Salud , Conducta de Reducción del Riesgo , Adolescente , Adulto , Anciano , Costos y Análisis de Costo , Femenino , Humanos , Masculino , Persona de Mediana Edad , Encuestas y Cuestionarios , Reino Unido , Adulto JovenRESUMEN
Electrotaxis is a naturally occurring phenomenon in which ionic gradients dictate the directed migration of cells involved in different biological processes such as wound healing, embryonic development, or cancer metastasis. To investigate these processes, direct current (DC) has been used to generate electric fields capable of eliciting an electrotactic response in cells. However, the need for metallic electrodes to deliver said currents has hindered electrotaxis research and the application of DC stimulation as medical therapy. This study aimed to investigate the capability of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT/PSS) on sputtered iridium oxide film (SIROF) electrodes to generate stable direct currents. The electrochemical properties of PEDOT/PSS allow ions to be released and reabsorbed depending on the polarity of the current flow. SIROF stabilized PEDOT/PSS electrodes demonstrated exceptional stability in voltage and current controlled DC stimulation for periods of up to 12 hours. These electrodes were capable of directing cell migration of the rat prostate cancer cell line MAT-LyLu in a microfluidic chamber without the need for chemical buffers. This material combination shows excellent promise for accelerating electrotaxis research and facilitating the translation of DC stimulation to medical applications thanks to its biocompatibility, ionic charge injection mechanisms, and recharging capabilities in a biological environment.
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Compuestos Bicíclicos Heterocíclicos con Puentes , Polímeros , Animales , Iridio , Masculino , RatasRESUMEN
Bioelectronic devices, interfacing neural tissue for therapeutic, diagnostic, or rehabilitation purposes, rely on small electrode contacts in order to achieve highly sophisticated communication at the neural interface. Reliable recording and safe stimulation with small electrodes, however, are limited when conventional electrode metallizations are used, demanding the development of new materials to enable future progress within bioelectronics. In this study, we present a versatile process for the realization of nanostructured platinum (nanoPt) coatings with a high electrochemically active surface area, showing promising biocompatibility and providing low impedance, high charge injection capacity, and outstanding long-term stability both for recording and stimulation. The proposed electrochemical fabrication process offers exceptional control over the nanoPt deposition, allowing the realization of specific coating morphologies such as small grains, pyramids, or nanoflakes, and can moreover be scaled up to wafer level or batch fabrication under economic process conditions. The suitability of nanoPt as a coating for neural interfaces is here demonstrated, in vitro and in vivo, revealing superior stimulation performance under chronic conditions. Thus, nanoPt offers promising qualities as an advanced neural interface coating which moreover extends to the numerous application fields where a large (electro)chemically active surface area contributes to increased efficiency.
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Electrónica , Nanoestructuras/química , Platino (Metal)/química , Animales , Materiales Biocompatibles/química , Encéfalo/fisiología , Estimulación Eléctrica , Ratones , Ratones Endogámicos C57BL , Microelectrodos , Relación Señal-RuidoRESUMEN
Implantable neural interfaces advance the possibilities for neuroscientists to study the brain. They are also promising for use in a multitude of bioelectronic therapies. Electrode technology plays a central role in these developments, as the electrode surfaces form the physical interfaces between technology and the biological targets. Despite this, a common understanding of how electrodes should best be evaluated and compared with respect to their efficiency in recording and stimulation is currently lacking. Without broadly accepted performance tests, it is difficult to rank the many suggestions for electrode materials available in the literature, or to identify where efforts should be focused to advance the field most efficiently. This tutorial critically discusses the most relevant performance tests for characterization of neural interface electrodes and explains their implementation, interpretation and respective limitations. We propose a unified standard to facilitate transparent reporting on electrode performance, promote efficient scientific process and ultimately accelerate translation into clinical practice.
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Encéfalo/fisiología , Estimulación Eléctrica/instrumentación , Electrodos Implantados , Electrónica/instrumentación , Animales , Espectroscopía Dieléctrica/instrumentación , Espectroscopía Dieléctrica/métodos , Estimulación Eléctrica/métodos , Técnicas Electroquímicas/instrumentación , Técnicas Electroquímicas/métodos , Electrónica/métodos , Diseño de Equipo , Humanos , MicroelectrodosRESUMEN
The fabrication of stretchable conductive material through vapor phase polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT) is presented alongside a method to easily pattern these materials with nanosecond laser structuring. The devices were constructed from sheets of vapor phase polymerized PEDOT doped with tosylate on pre-stretched elastomeric substrates followed by laser structuring to achieve the desired geometrical shape. Devices were characterized for electrical conductivity, morphology, and electrical integrity in response to externally applied strain. Fabricated PEDOT sheets displayed a conductivity of 53.1 ± 1.2 S cm-1; clear buckling in the PEDOT microstructure was observed as a result of pre-stretching the underlying elastomeric substrate; and the final stretchable electronic devices were able to remain electrically conductive with up to 100% of externally applied strain. The described polymerization and fabrication steps achieve highly processable and patternable functional conductive polymer films, which are suitable for stretchable electronics due to their ability to withstand externally applied strains of up to 100%.
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Structural biocompatibility is a fundamental requirement for chronically stable bioelectronic devices. Newest neurotechnologies are increasingly focused on minimizing the foreign body response through the development of devices that match the mechanical properties of the implanted tissue and mimic its surface composition, often compromising on their robustness. In this study, an analytical approach is proposed to determine the threshold of conformability for polyimide-based electrocorticography devices. A finite element model was used to quantify the depression of the cortex following the application of devices mechanically above or below conformability threshold. Findings were validated in vivo on rat animal models. Impedance measurements were performed for 40 days after implantation to monitor the status of the biotic/abiotic interface with both conformable and non-conformable implants. Multi-unit activity was then recorded for 12 weeks after implantation using the most compliant device type. It can therefore be concluded that conformability is an essential prerequisite for steady and reliable implants which does not only depend on the Young's modulus of the device material: it strongly relies on the relation between tissue curvature at the implantation site and corresponding device's thickness and geometry, which eventually define the moment of inertia and the interactions at the material-tissue interface.
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Corteza Cerebral , Animales , Impedancia Eléctrica , Electrodos Implantados , Microelectrodos , Modelos Animales , RatasRESUMEN
Spatio-temporally controlled drug release based on conducting polymer films offers a powerful technology to improve the tissue integration for implantable neuroprobes. We here explore the release efficiency of such systems in order to improve the understanding of the release mechanism and allow for optimized implementation of this technology into future drug release applications. By exposing drug loaded PEDOT coatings of different thicknesses to a multitude of release signals, along with optimizing the steps during the polymer synthesis, we could identify a highly reproducible electrostatically controlled drug release next to a slow diffusion driven release component. The release efficiency was moreover observed to be higher for a cyclic voltammetry signal in comparison to release driven by a constant potential. Biphasic current pulses, as used during neural stimulation, did not allow for long enough diffusion times to yield efficient active drug expulsion from the polymer films. A quantitative analysis could confirm an overall linear dependency between drug release and film thickness. The amount of drug released in response to the trigger signals was however not linearly correlated with the amount of charge applied. By combining these findings we could develop a model which accurately describes the drug release mechanism from a PEDOT film. The proposed model thereby points the way for how actively controlled, and diffusion related, release can be tuned for obtaining delivery dynamics tailored to specific applications.
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Compuestos Bicíclicos Heterocíclicos con Puentes/química , Dexametasona/administración & dosificación , Sistemas de Liberación de Medicamentos , Modelos Teóricos , Polímeros/química , Preparaciones de Acción Retardada , Dexametasona/química , Liberación de Fármacos , Reproducibilidad de los ResultadosRESUMEN
PARP3 has been shown to be a key driver of TGFß-induced epithelial-to-mesenchymal transition (EMT) and stemness in breast cancer cells, emerging as an attractive therapeutic target. Nevertheless, the therapeutic value of PARP3 inhibition has not yet been assessed. Here we investigated the impact of the absence of PARP3 or its inhibition on the tumorigenicity of BRCA1-proficient versus BRCA1-deficient breast cancer cell lines, focusing on the triple-negative breast cancer subtype (TNBC). We show that PARP3 knockdown exacerbates centrosome amplification and genome instability and reduces survival of BRCA1-deficient TNBC cells. Furthermore, we engineered PARP3-/- BRCA1-deficient or BRCA1-proficient TNBC cell lines using the CRISPR/nCas9D10A gene editing technology and demonstrate that the absence of PARP3 selectively suppresses the growth, survival and in vivo tumorigenicity of BRCA1-deficient TNBC cells, mechanistically via effects associated with an altered Rictor/mTORC2 signaling complex resulting from enhanced ubiquitination of Rictor. Accordingly, PARP3 interacts with and ADP-ribosylates GSK3ß, a positive regulator of Rictor ubiquitination and degradation. Importantly, these phenotypes were rescued by re-expression of a wild-type PARP3 but not by a catalytic mutant, demonstrating the importance of PARP3's catalytic activity. Accordingly, reduced survival and compromised Rictor/mTORC2 signaling were also observed using a cell-permeable PARP3-specific inhibitor. We conclude that PARP3 and BRCA1 are synthetic lethal and that targeting PARP3's catalytic activity is a promising therapeutic strategy for BRCA1-associated cancers via the Rictor/mTORC2 signaling pathway.
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Proteína BRCA1/genética , Proteínas de Ciclo Celular/genética , Poli(ADP-Ribosa) Polimerasas/genética , Proteína Asociada al mTOR Insensible a la Rapamicina/genética , Neoplasias de la Mama Triple Negativas/genética , Animales , Línea Celular Tumoral , Movimiento Celular/genética , Transición Epitelial-Mesenquimal/genética , Femenino , Xenoinjertos , Humanos , Diana Mecanicista del Complejo 2 de la Rapamicina/genética , Ratones , Transducción de Señal , Factor de Crecimiento Transformador beta/genética , Neoplasias de la Mama Triple Negativas/patologíaRESUMEN
The excessive use of antifungal agents, compounded by the shortage of new drugs being introduced into the market, is causing the accumulation of multi-resistance phenotypes in many fungal strains. Consequently, new alternative molecules to conventional antifungal agents are urgently needed to prevent the emergence of fungal resistance. In this context, Cateslytin (Ctl), a natural peptide derived from the processing of Chromogranin A, has already been described as an effective antimicrobial agent against several pathogens including Candida albicans. In the present study, we compared the antimicrobial activity of two conformations of Ctl, L-Ctl and D-Ctl against Candida albicans. Our results show that both D-Ctl and L-Ctl were potent and safe antifungal agents. However, in contrast to L-Ctl, D-Ctl was not degraded by proteases secreted by Candida albicans and was also stable in saliva. Using video microscopy, we also demonstrated that D-Ctl can rapidly enter C. albicans, but is unable to spread within a yeast colony unless from a mother cell to a daughter cell during cellular division. Besides, we revealed that the antifungal activity of D-Ctl could be synergized by voriconazole, an antifungal of reference in the treatment of Candida albicans related infections. In conclusion, D-Ctl can be considered as an effective, safe and stable antifungal and could be used alone or in a combination therapy with voriconazole to treat Candida albicans related diseases including oral candidosis.
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Antifúngicos/farmacología , Candida albicans/efectos de los fármacos , Candidiasis Bucal/tratamiento farmacológico , Cromogranina A/farmacología , Fragmentos de Péptidos/farmacología , División Celular/efectos de los fármacos , Línea Celular , Humanos , Pruebas de Sensibilidad Microbiana , Péptidos/farmacología , Voriconazol/farmacologíaRESUMEN
Conducting polymers (CPs) have frequently been described as outstanding coating materials for neural microelectrodes, providing significantly reduced impedance or higher charge injection compared to pure metals. Usability has until now, however, been limited by poor adhesion of polymers like poly(3,4-ethylenedioxythiophene) (PEDOT) to metallic substrates, ultimately precluding long-term applications. The aim of this study was to overcome this weakness of CPs by introducing two novel adhesion improvement strategies that can easily be integrated with standard microelectrode fabrication processes. Iridium Oxide (IrOx) demonstrated exceptional stability for PEDOT coatings, resulting in polymer survival over 10â¯000 redox cycles and 110 days under accelerated aging conditions at 60 °C. Nanostructured Pt was furthermore introduced as a purely mechanical adhesion promoter providing 10-fold adhesion improvement compared to smooth Pt substrates by simply altering the morphology of Pt. This layer can be realized in a very simple process that is compatible with any electrode design, turning nanostructured Pt into a universal adhesion layer for CP coatings. By the introduction of these adhesion-promoting strategies, the weakness of CP-based neural probes can ultimately be eliminated and true long-term stable use of PEDOT on neural probes will be possible in future electrode generations.
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Nanoestructuras , Compuestos Bicíclicos Heterocíclicos con Puentes , Humanos , Microelectrodos , Platino (Metal) , PolímerosRESUMEN
The rise of antimicrobial resistant microorganisms constitutes an increasingly serious threat to global public health. As a consequence, the efficacy of conventional antimicrobials is rapidly declining, threatening the ability of healthcare professionals to cure common infections. Over the last two decades host defense peptides have been identified as an attractive source of new antimicrobials. In the present study, we characterized the antibacterial and mechanistic properties of D-Cateslytin (D-Ctl), a new epipeptide derived from L-Cateslytin, where all L-amino acids were replaced by D-amino acids. We demonstrated that D-Ctl emerges as a potent, safe and robust peptide antimicrobial with undetectable susceptibility to resistance. Using Escherichia coli as a model, we reveal that D-Ctl targets the bacterial cell wall leading to the permeabilization of the membrane and the death of the bacteria. Overall, D-Ctl offers many assets that make it an attractive candidate for the biopharmaceutical development of new antimicrobials either as a single therapy or as a combination therapy as D-Ctl also has the remarkable property to potentiate several antimicrobials of reference such as cefotaxime, amoxicillin and methicillin.