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1.
Ann Biomed Eng ; 48(4): 1230-1240, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31916125

RESUMO

Irreversible electroporation (IRE) is an emerging technology for non-thermal ablation of solid tumors. This study sought to integrate electrodes into microporous poly(caprolactone) (PCL) scaffolds previously shown to recruit metastasizing cancer cells in vivo in order to facilitate application of IRE to disseminating cancer cells. As the ideal parallel plate geometry would render much of the porous scaffold surface inaccessible to infiltrating cells, numerical modeling was utilized to predict the spatial profile of electric field strength within the scaffold for alternative electrode designs. Metal mesh electrodes with 0.35 mm aperture and 0.16 mm wire diameter established electric fields with similar spatial uniformity as the parallel plate geometry. Composite PCL-IRE scaffolds were fabricated by placing cylindrical porous PCL scaffolds between two PCL dip-coated stainless steel wire meshes. PCL-IRE scaffolds exhibited no difference in cell infiltration in vivo compared to PCL scaffolds. In addition, upon application of IRE in vivo, cells infiltrating the PCL-IRE scaffolds were successfully ablated, as determined by histological analysis 3 days post-treatment. The ability to establish homogeneous electric fields within a biomaterial that can recruit metastatic cancer cells, especially when combined with immunotherapy, may further advance IRE technology beyond solid tumors to the treatment of systemic cancer.

2.
Int J Hyperthermia ; 36(1): 130-138, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30676126

RESUMO

Focal thermal therapy (Heat), cryosurgery (Cryo) and irreversible electroporation (IRE) are increasingly used to treat cancer. However, local recurrence and systemic spread are persistent negative outcomes. Nevertheless, emerging work with immunotherapies (i.e., checkpoint blockade or dendritic cell (DC) vaccination) in concert with focal therapies may improve outcomes. To understand the role of focal therapy in priming the immune system for immunotherapy, an in vitro model of T cell response after exposure to B16 melanoma cell lysates after lethal exposures was designed. Exposure included: Heat (50 °C, 30 min), Cryo (-80 °C, 30 min) and IRE (1250 V/cm, 99 pulses, 50 µs pulses with 1 Hz intervals). After viability assessment (CCK-8 assay), cell lysates were collected and assessed for protein release (BCA assay), protein denaturation (FTIR-spectroscopy), TRP-2 antigen release (western blot), and T cell activation (antigen-specific CD8 T cell proliferation). Results showed IRE released the most protein and antigen (TRP-2), followed by Cryo and Heat. In contrast, Cryo released the most native (not denatured) protein, compared to IRE and Heat. Finally, IRE dramatically outperformed both Cryo and Heat in T cell activation while Cryo modestly outperformed Heat. This study demonstrates that despite all focal therapies ability to destroy cells, the 'quantity' (i.e., amount) and 'quality' (i.e., molecular state) of tumor protein (including antigen) released can dramatically change the ensuing priming of the immune system. This suggests protein-based metrics whereby focal therapies can be designed to prime the immune system in concert with immunotherapies to eventually achieve improved and durable cancer treatment in vivo.


Assuntos
Antígenos de Neoplasias/metabolismo , Linfócitos T CD8-Positivos/imunologia , Neoplasias/imunologia , Animais , Humanos , Camundongos , Camundongos Transgênicos
3.
Biomaterials ; 166: 27-37, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29533788

RESUMO

Currently, there are very few therapeutic options for treatment of metastatic disease, as it often remains undetected until the burden of disease is too high. Microporous poly(ε-caprolactone) biomaterials have been shown to attract metastasizing breast cancer cells in vivo early in tumor progression. In order to enhance the therapeutic potential of these scaffolds, they were modified such that infiltrating cells could be eliminated with non-invasive focal hyperthermia. Metal disks were incorporated into poly(ε-caprolactone) scaffolds to generate heat through electromagnetic induction by an oscillating magnetic field within a radiofrequency coil. Heat generation was modulated by varying the size of the metal disk, the strength of the magnetic field (at a fixed frequency), or the type of metal. When implanted subcutaneously in mice, the modified scaffolds were biocompatible and became properly integrated with the host tissue. Optimal parameters for in vivo heating were identified through a combination of computational modeling and ex vivo characterization to both predict and verify heat transfer dynamics and cell death kinetics during inductive heating. In vivo inductive heating of implanted, tissue-laden composite scaffolds led to tissue necrosis as seen by histological analysis. The ability to thermally ablate captured cells non-invasively using biomaterial scaffolds has the potential to extend the application of focal thermal therapies to disseminated cancers.


Assuntos
Materiais Biocompatíveis , Hipertermia Induzida , Tecidos Suporte , Animais , Humanos , Hipertermia Induzida/instrumentação , Hipertermia Induzida/métodos , Camundongos , Metástase Neoplásica/terapia , Neoplasias/patologia , Neoplasias/terapia , Engenharia Tecidual/métodos
4.
Sci Rep ; 7(1): 16457, 2017 11 28.
Artigo em Inglês | MEDLINE | ID: mdl-29184189

RESUMO

Multi-core fibers (MCFs) have sparked a new paradigm in optical communications and open new possibilities and applications in experimental physics and other fields of science, such as biological and medical imaging. In many of these cases, ultra-short pulse propagation is revealed as a key factor that enables us to exploit the full potential of this technology. Unfortunately, the propagation of such pulses in real MCFs has not yet been modelled considering polarization effects or typical random medium perturbations, which usually give rise to both longitudinal and temporal birefringent effects. Using the concept of local modes, we develop here an accurate ultra-short pulse propagation model that rigorously accounts for these phenomena in single-mode MCFs. Based on this theory, we demonstrate analytically and numerically the intermodal dispersion between different LP01 polarized core modes induced by these random perturbations when propagating femtosecond pulses in the linear and nonlinear fiber regimes. The ever-decreasing core-to-core distance significantly enhances the intermodal dispersion induced by these birefringent effects, which can become the major physical impairment in the single-mode regime. To demonstrate the power of our model, we give explicit strategies to reduce the impact of this optical impairment by increasing the MCF perturbations.

5.
Opt Express ; 25(20): 24650-24657, 2017 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-29041410

RESUMO

This paper is focused on the characterization of a fiber Bragg grating (FBG) sensor interrogation system based on a fiber ring laser with a semiconductor optical amplifier as the gain medium, and an in-loop electro-optical modulator. This system operates as a switchable active (pulsed) mode-locked laser. The operation principle of the system is explained theoretically and validated experimentally. The ability of the system to interrogate an array of different FBGs in wavelength and spatial domain is demonstrated. Simultaneously, the influence of several important parameters on the performance of the interrogation technique has been investigated. Specifically, the effects of the bandwidth and the reflectivity of the FBGs, the SOA gain, and the depth of the intensity modulation have been addressed.

6.
Int J Neural Syst ; 26(5): 1650040, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27255800

RESUMO

In this paper, we use the neural property known as intrinsic plasticity to develop neural network models that resemble the koniocortex, the fourth layer of sensory cortices. These models evolved from a very basic two-layered neural network to a complex associative koniocortex network. In the initial network, intrinsic and synaptic plasticity govern the shifting of the activation function, and the modification of synaptic weights, respectively. In this first version, competition is forced, so that the most activated neuron is arbitrarily set to one and the others to zero, while in the second, competition occurs naturally due to inhibition between second layer neurons. In the third version of the network, whose architecture is similar to the koniocortex, competition also occurs naturally owing to the interplay between inhibitory interneurons and synaptic and intrinsic plasticity. A more complex associative neural network was developed based on this basic koniocortex-like neural network, capable of dealing with incomplete patterns and ideally suited to operating similarly to a learning vector quantization network. We also discuss the biological plausibility of the networks and their role in a more complex thalamocortical model.


Assuntos
Plasticidade Neuronal , Algoritmos , Teorema de Bayes , Córtex Cerebral/fisiologia , Simulação por Computador , Humanos , Aprendizado de Máquina , Modelos Neurológicos , Inibição Neural/fisiologia , Vias Neurais/fisiologia , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Software , Tálamo/fisiologia
7.
Orbit ; 35(4): 181-6, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27322024

RESUMO

Having to remove the sclera, fat and the optic nerve in patients undergoing an enucleation, translates in a larger volume that needs to be replaced to achieve good motility and aesthetic results. Using a 20 or 22 mm implant can only partially replace the removed volume. We report the results of our enucleation technique, which includes the use of a porous orbital implant combined with a primary fat graft to replace a higher percentage of the removed volume to achieve a better cosmetic outcome and to avoid implant related complications in high risk patients. Prospective, non-randomized study of enucleated patients for whom porous orbital implantation was performed with anterior placement of a fat auto-graft. The development of implant extrusion or exposure was recorded as well as the presence of conjunctival wound dehiscence and infection. Orbital volume was clinically and radiologically evaluated as well. Twenty-eight patients were included, with a postop follow-up of at least 6 months (6-79 months). No cases of migration or extrusion were found. One case of a large exposure resolved completely. All MRI demonstrated proper implant-graft integration and vascularisation. The aesthetic result and the symmetry were very adequate, with Hertel differences of less than 2 mm in all cases and good motility range. The fat graft is well tolerated, showing low incidence of implant-related complications whilst maintaining good volume and motility.


Assuntos
Tecido Adiposo/transplante , Enucleação Ocular/métodos , Órbita/cirurgia , Implantes Orbitários , Procedimentos Cirúrgicos Reconstrutivos , Umbigo/transplante , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Órbita/diagnóstico por imagem , Porosidade , Estudos Prospectivos , Implantação de Prótese , Transplante Autólogo
8.
Stem Cells Transl Med ; 5(7): 970-9, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27177577

RESUMO

UNLABELLED: Tissue organoids are a promising technology that may accelerate development of the societal and NIH mandate for precision medicine. Here we describe a robust and simple method for generating cerebral organoids (cOrgs) from human pluripotent stem cells by using a chemically defined hydrogel material and chemically defined culture medium. By using no additional neural induction components, cOrgs appeared on the hydrogel surface within 10-14 days, and under static culture conditions, they attained sizes up to 3 mm in greatest dimension by day 28. Histologically, the organoids showed neural rosette and neural tube-like structures and evidence of early corticogenesis. Immunostaining and quantitative reverse-transcription polymerase chain reaction demonstrated protein and gene expression representative of forebrain, midbrain, and hindbrain development. Physiologic studies showed responses to glutamate and depolarization in many cells, consistent with neural behavior. The method of cerebral organoid generation described here facilitates access to this technology, enables scalable applications, and provides a potential pathway to translational applications where defined components are desirable. SIGNIFICANCE: Tissue organoids are a promising technology with many potential applications, such as pharmaceutical screens and development of in vitro disease models, particularly for human polygenic conditions where animal models are insufficient. This work describes a robust and simple method for generating cerebral organoids from human induced pluripotent stem cells by using a chemically defined hydrogel material and chemically defined culture medium. This method, by virtue of its simplicity and use of defined materials, greatly facilitates access to cerebral organoid technology, enables scalable applications, and provides a potential pathway to translational applications where defined components are desirable.


Assuntos
Encéfalo/citologia , Meios de Cultura/química , Hidrogel de Polietilenoglicol-Dimetacrilato/farmacologia , Células-Tronco Pluripotentes Induzidas/fisiologia , Organoides/fisiologia , Técnicas de Cultura de Tecidos/métodos , Fenômenos Biomecânicos , Encéfalo/metabolismo , Diferenciação Celular/genética , Células Cultivadas , Meios de Cultura/farmacologia , Expressão Gênica , Humanos , Hidrogel de Polietilenoglicol-Dimetacrilato/química , Neurônios/citologia , Neurônios/fisiologia , Organoides/citologia
9.
Neural Plast ; 2016: 4131395, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27088014

RESUMO

The gate control theory of pain proposed by Melzack and Wall in 1965 is revisited through two mechanisms of neuronal regulation: NMDA synaptic plasticity and intrinsic plasticity. The Melzack and Wall circuit was slightly modified by using strictly excitatory nociceptive afferents (in the original arrangement, nociceptive afferents were considered excitatory when they project to central transmission neurons and inhibitory when projecting to substantia gelatinosa). The results of our neurocomputational model are consistent with biological ones in that nociceptive signals are blocked on their way to the brain every time a tactile stimulus is given at the same locus where the pain was produced. In the computational model, the whole set of parameters, independently of their initialization, always converge to the correct values to allow the correct computation of the circuit. To test the model, other painful conditions were analyzed: phantom limb pain, wind-up and wind-down pain, breakthrough pain, and demyelinating syndromes like Guillain-Barré and multiple sclerosis.


Assuntos
Modelos Neurológicos , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Dor/fisiopatologia , Transmissão Sináptica/fisiologia , Simulação por Computador , Humanos , Vias Neurais/fisiopatologia , Substância Gelatinosa/fisiologia
10.
Opt Express ; 15(6): 3177-89, 2007 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-19532556

RESUMO

In this paper, we study analytically and numerically the light propagation in microring resonator chains that exhibit distributed loss or gain. We derive the stability conditions for the latter and demonstrate the feasibility of the group index control within a certain amplification range. Possible applications of the discussed effects are proposed.

11.
Aval. psicol ; 4(2): 125-139, nov. 2005. tab
Artigo em Português | Index Psicologia - Periódicos técnico-científicos | ID: psi-34010

RESUMO

Este estudo visou estudar, em uma amostra brasileira, a confiabilidade e a validade do Questionário para Medo de Aranha (FSQ), do Questionário para Fobia de Aranha (SPQ) e do Questionário de Automaticidade e Irracionalidade (AI). Os questionários foram traduzidos do Inglês e corrigidos por professores de Inglês. A amostra foi constituída de 120 pessoas. 84 estudantes de graduação e 36 indivíduos com medo de aranha. Os testes mostraram-se altamente correlacionados. Os coeficientes alfa de Crombach demonstraram consistência interna dos instrumentos. Os escores dos universitários diferiram significativamente dos escores de aracnofóbicos (25 sujeitos), demonstrando validade de critério concorrente. Para os três instrumentos a análise fatorial sugeriu adaptações sócio-culturais(AU)


Assuntos
Adulto , Humanos , Masculino , Feminino
12.
Aval. psicol ; 4(2): 125-139, nov. 2005. tab
Artigo em Português | LILACS | ID: lil-469445

RESUMO

Este estudo visou estudar, em uma amostra brasileira, a confiabilidade e a validade do Questionário para Medo de Aranha (FSQ), do Questionário para Fobia de Aranha (SPQ) e do Questionário de Automaticidade e Irracionalidade (AI). Os questionários foram traduzidos do Inglês e corrigidos por professores de Inglês. A amostra foi constituída de 120 pessoas. 84 estudantes de graduação e 36 indivíduos com medo de aranha. Os testes mostraram-se altamente correlacionados. Os coeficientes alfa de Crombach demonstraram consistência interna dos instrumentos. Os escores dos universitários diferiram significativamente dos escores de aracnofóbicos (25 sujeitos), demonstrando validade de critério concorrente. Para os três instrumentos a análise fatorial sugeriu adaptações sócio-culturais.


Assuntos
Humanos , Masculino , Feminino , Adulto , Transtornos Fóbicos , Psicometria
13.
Rev. colomb. cienc. pecu ; 15(2): 213-225, ago. 2002. tab
Artigo em Espanhol | LILACS | ID: lil-473998

RESUMO

La ganadería, una actividad generalizada y desarrollada prácticamente en todo el país, considerada como un renglón socioeconómico de gran importancia para el desarrollo del campo y que ha sido y es cuestionada fuertemente por su desempeño productivo e impacto ambiental, debe equilibrarse en un nivel tecnológico aceptable y sostenible, que combine la productividad de los sistemas intensivos con las bondades de los extensivos. Esta monografía se realizó con el objetivo de analizar la situación de la ganadería bovina de carne en Colombia y plantear estrategias que promuevan su competitividad y sostenibilidad. La ganadería colombiana esta caracterizada por ser una actividad extensiva-extractiva, con bajos niveles de inversión y un deficiente desarrollo de acciones administrativas que la promuevan empresarialmente en un mercado globalizado, que es altamente competitivo. El silvopastoreo, los sistemas de conservación de forrajes y el uso de bloques multinutricionales, constituyen estrategias que pueden generar importantes avances en los aspectos productivo y ambiental, enmarcados en las exigencias de los mercados globalizados.


Assuntos
Bovinos , Ração Animal , Bovinos , Economia , Agricultura Florestal , Indústria da Carne
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